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DELIVERABLE REPORT

DELIVERABLE N0: D3.4

DISSEMINATION LEVEL: PUBLIC (PU)

TITLE: DEMONSTRATOR OF A MISSION ADAPTABLE HYBRID-ON-DEMAND

DRIVELINE INSTALLED IN A TRACTOR SEMI-TRAILER VEHICLE

DATE: 31.08.2017

VERSION: FINAL

AUTHOR(S): GUNTER NITZSCHE, SEBASTIAN WAGNER (FHG IVI)

REVIEWED BY: BIRGER QUECKENSTEDT (SCB), ALFREDO SELAS (BOSCH),

RAMANAN KARTHIK (VOLVO)

APPROVED BY: COORDINATOR – PAUL ADAMS (VOLVO)

GRANT AGREEMENT N0: 605170

PROJECT TYPE: THEME 7 TRANSPORT – SST GC.SST.2012.1-5: INTEGRATION AND

OPTIMISATION OF RANGE EXTENDERS ON ELECTRIC VEHICLES

PROJECT ACRONYM: TRANSFORMERS

PROJECT TITLE: CONFIGURABLE AND ADAPTABLE TRUCKS AND TRAILERS FOR

OPTIMAL TRANSPORT EFFICIENCY

PROJECT START DATE: 01/09/2013

PROJECT WEBSITE: WWW.TRANSFORMERS-PROJECT.EU

COORDINATION: VOLVO (SE)

PROJECT MANAGEMENT: UNIRESEARCH (NL)

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605170 – D3.4 – Demonstrator Of A Mission Adaptable Hybrid-On-Demand Driveline Installed In A Tractor Semi-Trailer Vehiclereport On Hod Driveline Running In The Trailer 2 / 24

Executive summary

The objective of the EU-funded project TRANSFORMERS is to design, develop, and demonstrate truck-

trailer concepts for long-haulage applications featuring high energy efficiency. Therefore,

TRANSFORMERS combines a modular approach for mission rightsizing by means of hybridization and

a trailer design that addresses simultaneously aerodynamics and load efficiency improvements. The

overall goal is to achieve a 25% higher load efficiency (in energy/km.tn) in a real world application,

while taking the needs to maintain road infrastructure and traffic safety into account.

A key innovation of TRANSFORMERS is the so-called Hybrid-on-Demand-Driveline (HoD-Driveline).

For the first time, this system enables an augmentation of conventionally driven trucks and tractors to

fully functional mission-adaptable hybrid vehicles, simply by coupling them to an innovative trailer

equipped with an electric driveline. Hence, the HoD-Driveline concept is applicable to many kinds of

truck-trailer combinations.

In addition to the HoD-Driveline concept TRANSFORMERS has developed a pre-standardisation HoD-

Framework document. The objective of this framework is:

to ensure the interoperability of the HoD-Driveline concept with today’s and with future trucks

featuring advanced energy management capabilities,

to provide a slim common interface between trucks and trailers, that requires only minimal

changes to the existing standard interface.

Deliverable D3.21 describes a first holistic draft of the pre-standardisation Hybrid-on-Demand

Framework document including:

Specification of the logical and E/E-architecture of the HoD-Driveline,

Specification of the necessary interfaces, and

Specification of the functions of affected electronic control units.

This deliverable summarizes the key findings regarding the HoD framework in Chapter 5.2 including

the lessons learned during demonstrator implementation and real world testing. Throughout the

whole development process, the HoD-Framework was continuously refined. Primarily, the changes

affected the interfaces defined in D3.2. Several signals were added, e.g. due to safety and optional

man-machine interface requirements.

Based on the HoD framework specifications deliverable D3.4 shows that the HoD system is

successfully integrated and running in a truck-semitrailer vehicle. The key achievements reported in

this deliverable are:

Electric driveline tested in the trailer,

Successful overall commissioning of HoD semitrailer with two trucks proving interoperability,

Proof of technical feasibility of the initial technical approach, and

Proof of the applicability of the HoD Framework.

1 Access to D3.1 and D3.2 or parts of it can be granted upon request. Please contact the project

coordinator. It is currently under discussion to make D3.2 available via EUCAR.

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Contents

Contents .............................................................................................................................. 3

List of Acronyms ................................................................................................................... 4

1 Introduction ................................................................................................................... 5

1.1 Scope ..................................................................................................................... 5

1.2 Context ................................................................................................................... 6

1.3 Technical background / system overview ..................................................................... 6

2 Overall HoD Framework System Architecture ...................................................................... 7

2.1 ECU Functionalities ................................................................................................... 7

2.1.1 VCU .................................................................................................................... 7

2.1.2 TDMS .................................................................................................................. 8

2.1.3 TEBS ................................................................................................................... 8

2.1.4 EMG-ECU ............................................................................................................. 9

2.1.5 ESU-ECU .............................................................................................................. 9

2.2 HoD Interfaces ......................................................................................................... 9

3 Demonstrator driveline ................................................................................................... 10

3.1 TDMS .................................................................................................................... 11

3.2 Self-contained ESU .................................................................................................. 11

3.3 EMG and EMG inverter ............................................................................................. 12

3.4 Gearbox with integrated Clutch ................................................................................. 12

4 Commissioning and Test Results ...................................................................................... 13

4.1 Clutch operation ...................................................................................................... 15

4.2 Brake blending ........................................................................................................ 16

4.3 On-road testing ....................................................................................................... 17

5 Conclusions ................................................................................................................... 20

5.1 General Findings ..................................................................................................... 20

5.2 HoD-Framework ...................................................................................................... 22

5.3 Lessons Learnt ........................................................................................................ 23

6 Acknowledgment ........................................................................................................... 24

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List of Acronyms

Akronym Description

ABS Anti-lock Braking System

ASR see TCS

CC Cruise Control

DA Destination Address

EBS Electronic Braking System

EBSI Electronic Braking System Interface

ECU Electronic Control Unit

EMG Electric Motor Generator of the trailer

EMGI Electric Motor Generator Interface

ESU Energy Storage Unit of the trailer

ESUI Energy Storage Unit Interface

HoD Hybrid-on-Demand

HoDD Hybrid-on-Demand-Driveline

HoDF Hybrid-on-Demand-Framework

HV High Voltage

ICE Internal Combustion Engine

LV Low Voltage

MMI Man Machine Interface

PDU Protocol Data Unit (see e.g. ISO 11992 Part 3)

PF PDU Format

PS PDU Specific

PTO Power Take-Off

PTCH Positive Temperature Coefficient Heater

RCP Rapid Control Prototyping

SA Source Address

SLOT Scaling, Limit, Offset and Transfer function definitions in J1939

TCS Traction Control System

TDMS Trailer Driveline Management System

TEBS Trailer Electronic Braking System

TEMS Trailer Energy Management System

TDN Trailer Drivetrain Network

VCU Vehicle Control Unit

VCUI Vehicle Control Unit Interface

VDC Vehicle Dynamics Control

VEMS Complete Vehicle Energy Management System

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1 Introduction

1.1 Scope

This document describes the key developments and commissioning steps for the electric/electronic

and functional integration of the Hybrid-on-Demand (HoD) driveline in the truck-semitrailer vehicle

combination. The TRANSFORMERS project built one HoD semitrailer. After the functional integration,

this semitrailer is able to operate with two different trucks provided by the OEMs involved.

The following tasks were performed for both trucks:

implementing, testing and commissioning of a truck gateway that provides the necessary

vehicle control unit interface (VCUI) signals,

connecting the semitrailer with each truck electronically,

commissioning and debugging the VCUI including the gateways,

step-wise commissioning of all functional/control systems (e.g. clutch control, torque control

etc.),

overall system integration/commissioning and

steadily debugging and optimization.

Figure 1 shows an overview of the whole system. It consists of an electric motor/generator (EMG), an

energy storage unit (ESU), a transmission/clutch unit between motor and drive axle, and a main

Trailer Drivetrain Management System (TDMS) as well as several auxiliary ECUs. TRANSFORMERS

implemented this concept in the tested HoD semitrailer.

Figure 1: Logical system architecture of the HoD-Framework

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1.2 Context

Today’s trucks are designed and optimized towards a limited set of use cases. In contrast, future

trucks should provide optimized transport efficiency for each mission. Within this context, the

driveline is a key component featuring a promising potential for optimizing energy and, as a result,

transport efficiency on a transport mission basis.

Work package WP3 of the TRANSFORMERS project develops an innovative, highly efficient, and

mission-adaptable driveline for tractor-semitrailer vehicles. This so-called Hybrid-on-Demand-

Driveline (HoDD) enables hybridization of trucks by coupling them to a trailer with a built-in electric

drivetrain2. The key features are:

Fully functional hybrid driveline by coupling a conventional driven truck with a HoD-Trailer,

Electric driveline within the trailer including Electric Motor Generator (EMG) and Energy

Storage Unit (ESU),

Configurable trailer driveline for mission adaption by an interchangeable ESU,

Slim communication interface between truck and trailer in order to limit changes to the truck

to the maximum possible extent.

To support a fast dissemination of the HoDD concept a corresponding pre-industrial standard is

developed as well. This so called Hybrid-on-Demand-Framework (HoDF) shall ensure compatibility

and interoperability of different trucks and trailers by defining a system architecture as well as

communication, electric and, where necessary, mechanical interfaces.

Furthermore, the HoDF proposes interface definitions for trailer drivetrain components such as Electric

Motor/Generators (EMG) and Energy Storage Units (ESU) in order to provide a new level of planning

certainty for component manufacturers and to enable lively commercial competition.

The framework is summarized in D3.2. It will be reused and further refined in the EU-co-funded

project AEROFLEX. In addition, the framework shall be made available to EUCAR and suitable trailer

manufacturers associations. This is the first step towards presenting it to ISO, in this case ISO TC22-

SC31 WG4, via appropriate national mirror groups - potentially via the German VDA mirror group on

brakes and steering systems. The document could also be shared with other research groups.

This document focuses on the main development steps and tests performed to integrate the electric

drivetrain into the truck-semitrailer combination.

1.3 Technical background / system overview

In general, the HoD framework considers two vehicle combinations:

Case A. Standard truck without holistic Vehicle Energy Management System (VEMS) is

coupled to the HoD-Trailer (Figure 2),

Case B. Future truck with HoDF-compliant Vehicle Energy Management System is coupled to

a HoD-Trailer (Figure 3).

This distinction is necessary, because standard trucks are not designed for operation with driven

trailers. Hence, for Case A the trailer driveline is only activated in predefined scenarios, to avoid

interferences with vehicle dynamics and advanced fuel-saving technologies, like e.g. gear shifting

strategy, weight estimation, cruise control strategy, or ECO-Roll. In contrast to that, the truck’s VEMS

is fully responsible for operating the trailer driveline in Case B applications.

For a comprehensive description of the framework’s capabilities and features including considered

vehicle combinations and operating conditions/vehicle states of each case refer to deliverable D3.1

and D3.23.

Due to the very high complexity of Case B and limitations of readily available truck-semitrailer

interfaces like, e.g. ISO11992 and J1939, TRANSFORMERS demonstrates Case A only, where the

trailer itself is responsible for the energy management. In order to provide the intended system

2 For further details and background information, refer to the TRANSFORMERS deliverable D3.1 and D3.2.

3 Access to D3.1 and D3.2 or parts of it can be granted upon request. Please contact the project

coordinator.

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functionality and properly respond to driver demands the trailer only needs to read signals from the

truck’s VCU.

For compatibility reasons with legacy trucks, sending signals back to the truck is avoided. The system

implementation proved that this is possible in principle. However, for monitoring and test driver

feedback purposes (MMI) signals like, e.g. HoD driveline state, ESU state of charge, and system

errors, are transmitted to the truck.

Figure 2: Structure of the HoD-Driveline for a HoD-Trailer coupled to a standard truck

(Case A)

Figure 3: Structure of the HoD-Driveline for a HoD-Trailer coupled to a VEMS-Truck

(Case B)

2 Overall HoD Framework System Architecture

TRANSFORMERS developed a multi-domain system architecture that in principle supports both Case A

and B applications while taking key features like interoperability, mission-based rightsizing,

modularity, and interchangeability on component level into account. This section describes the overall

system architecture of the demonstrator, which is as close as possible to Case A as described in D3.2.

As an introduction for the subsequently described details, Figure 1 shows the logical system

architecture and the scope of the HoD system. The key component is the TDMS with its built-in TEMS.

It controls the trailer driveline depending on information received from trucks VCU, ESUs, EMGs, and

TEBS. The individual functions of the system components as well as the interfaces between the

components are described in the subsequent sections.

2.1 ECU Functionalities

This section provides a high-level description of the ECU functions. Due to the different capabilities

and features of HoD Case A and B the functionalities of the VCU is different as well. Nevertheless, the

TDMS, ESU-ECU, and the EMG-ECU are in principle the same for both cases.

2.1.1 VCU

2.1.1.1 Case A

In Case A the truck VCU is assumed to be state of the art, which means they are not able to control

the HoD-driveline in detail. Instead, the TDMS is in charge of managing the trailer drivetrain based on

parameters/signals received from the truck. The truck and its VCU need to provide the following

functions:

Detect whether a standard or an HoD-Trailer is connected to the truck,

Implementation of trailer retarder control according to ISO 11992-2, and

Implementation of the Case A VCU-Interface as specified in HoD framework description.

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2.1.1.2 Case B

In Case B the truck is equipped with a comprehensive VEMS, which is able to use the trailer driveline

as a propulsion and energy recuperation device. Hence, the trucks VCU is in charge of controlling the

trailer drivetrain as a braking and propelling device, and the VEMS performs the entire vehicle energy

management by using all devices available. The tasks of the VCU are:

Detect whether a standard or a HoD-Trailer is connected to the truck,

Implement the Case B VCU-Interface as specified in HoD framework description,

Reads all necessary information describing the drivetrain capabilities from TDMS,

Optimizes the energy flow of the entire vehicle, and

Engage all driving and braking devices available according to the results of the energy

optimization.

2.1.2 TDMS

The TDMS encapsulates the complexity and the component diversity of the HoDD and provides an

easy to use interface for trucks/tractors. This approach ensures a broad interoperability between

different trucks/tractors and trailers/semitrailers.

The TDMS enables the trailer driveline, only if a truck with the required VCU- and EBS-Interfaces is

detected. The interface detection is mandatory because they provide the necessary truck parameters

for driving and braking via the electric driveline of the trailer. Based on the “handshake” result, the

TDMS continues with Case A or Case B operation. Otherwise, the trailer driveline remains disabled4.

The applied energy management strategy of Case A itself is not part of the HoDF. However, since

standard trucks were designed without knowledge of driven trailers, using the trailer driveline for

energy recuperation and driving is limited to a set of predefined scenarios.

In general the functionality of the TDMS is independent of Case A and B operation mode. The tasks

are:

Implement the VCU- and EBS-Interface,

Detect the capabilities of the truck via VCU- and EBS-Interface handshakes,

If applicable, decide whether to use Case A or B operation mode or to disable the driveline,

Implement a Case A operation mode based on a basic energy management strategy

Implement a Case B operation mode that encapsulates the internal structure and

implementation diversity of the HoDD by providing a device interface, which reports overall

nominal, maximal, and current driveline performance parameters to the VCU,

Limit EMG driving and braking to approved driving scenarios, and

Ensure the intrinsic safety of the HoDD by monitoring and if required shutting down the

trailer driveline components.

2.1.3 TEBS

The Trailer-EBS is a central component for the safety of the vehicle combination. According to German

homologation authorities and the current requirements of ECE Regulation R13 (Revision 6, released

on 24. 06. 2009) it must be in charge of performing all braking actions including HoD-recuperation

within the trailer. The detailed safety investigations revealed further that not only HoD-braking must

be approved by the TEBS but also propulsion from the HoDD.

This approval is not only necessary for safety reasons but also for not disturbing internal monitoring

and error handling functions of the TEBS. The tasks that need to be added to state of the art

electronic braking systems are:

Safely disable the HoD-Driveline in any emergency situation (ABS-events, TSC-events,

emergency braking etc.),

Implement the brake-blending function that prefers braking via HoDD instead of using

service brakes,

Implement a mechanism for receiving and approving brake and driving requests of the TDMS

via EBS interface, and

4 This functionality is not implemented in the demonstrator vehicle. It implements Case A only.

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Due to safety reasons, the TEBS should be able to prohibit EMG propulsion and braking

directly without involving the TDMS.

2.1.4 EMG-ECU

The task of the EMG-ECU is to control the EMG internally and provide an easy to use interface for the

TDMS that encapsulates EMG complexity and diversity. This functionality should ideally be integrated

in the inverter controller, which belongs to the electric machine. Nevertheless, it was implemented as

separate control unit in the demonstrator vehicle for easier adaptation. The required functions are:

Implement the high-level EMG-Interface as specified in the HoD framework description

including a digital signals used by the TEBS to disable EMG braking and driving,

Ensure the intrinsic safety of the EMG,

Measure and report internal EMG data like e.g. voltages, currents, torques,

Perform all low level functions to

o put the EMG into operation,

o operate the EMG, and

o shutdown the EMG

Perform internal error management and provide error reporting, and as an option

Implement an EMG cooling control system.

2.1.5 ESU-ECU

The task of the ESU-ECU is to control the ESU internally and provide an easy to use interface for the

TDMS that encapsulates ESU complexity and diversity. This functionality should ideally be integrated

in the battery management system itself. Nevertheless, it was implemented as separate control unit

in the demonstrator vehicle for easier adaptation. The required functions are:

Implement the high-level ESU-Interface as specified in the HoD framework description,

Ensure the intrinsic safety of the ESU,

Monitor and report the ESU health status,

Measure and report internal ESU data like e.g. voltages, currents, state of charge,

Perform all low level functions to

o put the ESU into operation,

o operate the ESU, and

o shutdown the ESU

Perform internal error management and provide error reporting, and as an option

Implement an ESU thermal management system (cooling and heating).

2.2 HoD Interfaces

The ECUs above exchange the necessary information by means of CAN-based communication

interfaces. Subsequently, these interfaces are described briefly:

VCU-Interface (VCUI): Is the interface between VCU and TDMS. This interface provides two

modes to ensure interoperability with standard/legacy and VEMS trucks. If the TDMS detects a

standard truck, the VCUI switches to unidirectional mode. The TDMS only reads signals from

the VCU, which enables retrofitting solutions. If the TDMS detects a truck compliant to Case B

of the HoD framework, the VCUI is also sending messages to the truck. The TDMS reports trailer

driveline performance/capability parameters to the VCU and receives driving/recuperation

requests in return.

EMG-Interface (EMGI): Is the interface between TDMS and EMG. This interface is part of the

HoD framework to support the development of compliant EMGs. During operation, the TDMS

controls the EMG power-flow according to performance/capability parameters reported by the

EMG used.

ESU-Interface (ESUI): Is the interface between TDMS and ESU. This interface is part of the

HoDF to support the development of framework compliant ESUs. During operation, the TDMS

controls the ESU power-flow according to performance/capability parameters reported by the

ESUs available.

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EBS-Interface (EBSI): Is the interface between TDMS and EBS of the trailer. The trailer EBS

provides a brake-blending functionality, which receives brake requests from the truck EBS and

distributes them between service brakes and electric braking (recuperation by EMG). Therefore,

the TDMS reports brake-related performance/capability parameters and receives brake requests

from the EBS of the trailer. Furthermore, the trailer EBS sends additional signals like e.g. ASR

and VDC events via EBS-Interface.

3 Demonstrator driveline

The demonstrator driveline E/E-Architecture is designed according to the logical architecture

described in the HoD framework (see Figure 1) in order to prove the concept in general. Due to

findings in the project like, e.g. signal availability, required efforts and available resources,

TRANSFORMERS focuses on demonstrating Case A only.

Figure 4 shows the details of the specific implementation including the technologies used for the

interfaces. The implementation follows the HoD framework proposal to the maximum possible extent.

This includes already defined and widely adopted communication protocols like ISO11992 and J1939.

The only nonconformity in communication protocols is the VCU interface. Instead of implementing

ISO11992 Part 3, a J1939 bus is used. The main reason is the flexibility and a far greater pre-defined

signal pool that enables more experimental freedom and a faster development process during the first

implementation of the system. Nevertheless, TRANSFORMERS achieved a solution that can be

implemented with the already existing signals of ISO11992 Part 3 as well. The Case A functionality

remains the same. The only drawback is a limited driver feedback mainly resulting from missing

signals like e.g. ESU state of charge, HoD status, and applied torque.

The following sections describe the details of key components of the demonstrator implementation. In

particular, these are:

TDMS,

ESU,

EMG and EMG inverter, and

Gearbox with Clutch.

Chapter 5 of this report summarizes the conclusions and lessons learned from the demonstrator

implementation with respect to the HoD framework.

TRANSFORMERS developed constitutive parts of ESU, Control Box, EMG, and EMG inverter. The

gearbox/clutch and the trailer axle are third party products. All components are installed, functionally

integrated, and tested in the semitrailer and the two trucks respectively.

TDMSVCU

Truck EBSTrailer

EBS

ISO11992-2

EBS-Interface(J1939)

HoD Signal Routing

Existing Interfaces

VCU-Interface(J1939)

Gate-way

ESU EMG

Trailer Drivetrain Network(J1939)

Figure 4: Overall System Architecture of the truck-semitrailer demonstrator vehicle

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3.1 TDMS

As defined in the framework the TDMS-ECU is the central trailer drivetrain management system,

which implements all high-level control functions. Even though a high-performance rapid control

prototyping system is used all functions of the TDMS can be easily transferred to automotive ECUs.

The TDMS-ECU is mounted in a water-resistant box on the left main beam of the trailer. It can be

easily accessed and maintained. The ECU is connected to the trailer EBS, the ESU-ECU, the EMG-ECU

and the truck by means of the respective communication interfaces.

In general, the implemented functions follow the component task description of section 2.1.2.

However, the demonstrator neglects all Case B related functions and the detection of truck

capabilities. In future, the system can be augmented to Case B with reasonable efforts.

A key finding is that safety functions are not necessarily centralized in the TDMS. Instead, EMG and

ESU should be intrinsically safe, and the TDMS is responsible for safety functions on system level.

3.2 Self-contained ESU

According to the HoD-Framework the ESU is designed as a self-contained unit with minimal signal

interfaces to the outside (see Figure 1). The ESU features only mechanical and electrical interfaces,

since the battery air cooling and heating system is already installed inside the ESU housing.

Therefore, the housing provides a sealed and a non-sealed section. The sealed section contains the

battery, ESU-ECU, water pump and water heater. The non-sealed sections contain the heat exchanger

and the cooling fans, see Figure 5.

ECUDC

DC

rela

ys

PTCH

ESU-conditioning Fans

ESU-conditoining PTC-Heater

ESU-conditioning-pump

ESU-ECULV-backup-batteryLV-DC/DC

below PTCH

ESU-conditioning heat exchanger sealed

non-sealed

ESU-battery

Connectors

Figure 5: Schematic inside view of ESU housing

The HoD Framework requires the ESU to have a power supply, a communication, and an HV interface

only. However, the demonstrator needed additional connectors. For example, due to limited voltage

compatibility of several passenger car components (heater, water pump) it was necessary to convert

the trucks supply voltage (24 V) to the standard passenger car voltage level (12 V). This voltage

converter is installed in the battery housing as well. The 12 V supply voltage is used to power all

battery auxiliaries but also the components of the external main Control Box. Hence, an additional

12 V supply voltage output connector is attached to the ESU. This additional connector is not

necessary in a series application if the auxiliaries and control hardware is compatible the 24 V truck

supply.

Furthermore, the EMG cooling system uses a HV fan (400 V) to control the cooling power. Hence, it is

necessary to have a stub from the main HV circuit to the fan. In TRANSFORMERS this stub is

branched off within the ESU housing and the EMG cooling fan is connected to it.

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Due to these two reasons, the TRANSFORMERS ESU features two additional connectors compared to

the original HoD Framework design. Both connectors are not required in a next generation system.

This proves the feasibility of the slim electrical and communication interface of the ESU as defined in

the HoD framework.

The ESU features an internal ESU-ECU that controls all battery related functions like the cooling and

heating system as well as key safety features like e.g. additional HV switches. Furthermore, it

provides a CAN-based HoD framework compliant ESU interface to the trailer drivetrain management

(TDMS) ECU. In the demonstrator, this ECU translates between the ESU interface and the proprietary

communication protocol provided by the battery.

TRANSFORMERS uses a separate ESU-ECU to implement a HoD-compliant ESU interface. This ECU

communicates with the TDMS and the proprietary ECU of the battery. In a potential series application

a separate ESU-ECU is not required if a HoD-compliant ESU is used, which implements the ESU

interface itself. This reduces the number of ECUs as well as the system complexity and costs.

3.3 EMG and EMG inverter

The electric motor/generator (EMG) is driven by an intelligent EMG inverter. Within this document,

this whole unit is called EMG. The inverter is mounted to the inner side of the left main beam. This

position ensures that the HV harness is safely covered beneath the trailer and between the massive

ladder frame. The selected mounting position also improves electromagnetic compatibility due to the

shielding properties of the ladder frame.

The motor/generator itself is directly attached to the gearbox, which is also mounted to the ladder

frame of the trailer. A HV harness connects the motor/generator with the EMG inverter, which

communicates with the EMG-ECU using a framework compliant CAN-based EMG interface.

TRANSFORMERS uses a separate EMG-ECU to implement a HoD-compliant EMG interface. Similar to

the battery, this ECU communicates with the TDMS and translates the messages to the proprietary

ECU of the battery. In a potential series application a separate EMG-ECU is not required if a HoD-

compliant EMG is used, which implements the EMG interface itself. This again reduces the number of

ECUs as well as the system complexity and costs.

While the TDMS-ECU manages the drivetrain as a whole, the EMG-ECU controls the EMG on system

component level. For example, when the TDMS requires a certain torque, the EMG-ECU sets the

required clutch state and executes the torque request at the EMG by communicating with the EMG

inverter.

3.4 Gearbox with integrated Clutch

A gearbox was installed to make sure that the EMG operates in its most efficient operating range

most of the time in long haulage applications. The ratio of the gearbox is 4:1. In addition, the driven

axle differential gearbox has a ratio of 2.93:1 resulting in an overall gear ratio between EMG and

wheels of 11.72:1. In future applications an application specific electric machine design could make

the gearbox obsolete, allowing for a reduction in both weight and cost.

The gearbox is equipped with a dog clutch. This is a reasonable technology with respect to wear and

maintenance efforts. Nevertheless, due to the underlying technical principle it is impossible to open

the clutch as long as torque is applied. This was identified as key drawback from a safety perspective,

e.g. if the opening process is too slow in certain safety critical situations. However, test drives showed

that the clutch opens fast enough to ensure the required safety level.

The safety issue can also be solved by using a friction clutch that opens in any situation independently

of the currently applied torque. This increases wear, maintenance efforts, and potentially decreases

the drivetrain efficiency. Hence, further investigations are necessary to select the most suitable clutch

technology.

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4 Commissioning and Test Results

All system modules described in chapter 3 are mechanically and electrically integrated into the trailer

(see Figure 6 and Figure 7). Based on this system installation a step-wise commissioning process was

performed in order to achieve the system integration of the electric HoD driveline on a functional

level.

TRANSFORMERS successfully performed the following steps:

1. Commissioning of ESU including all management functions like, e.g. cooling, heating, and

safety.

2. Commissioning of the EMG and the EMG inverter initially using an external HV supply, later

with the ESU in the trailer.

3. Commissioning of the clutch to enable opening and closing the clutch by the EMG-ECU

4. Combining ESU, EMG, EMG inverter and clutch system to a fully functional electric drivetrain

by means of the TDMS-ECU

5. Combining the HoD-Trailer with the HoD-Trucks and commissioning the whole combinations

6. Commissioning of the EBS interface and the corresponding brake blending functionality

These steps required extensive function and software development efforts for TDMS-ECU, EMG-ECU,

ESU-ECU, VCU-Gateway and EBS-ECU. Each of these ECUs were equipped with a specific operating

system, state machines, error handling routines, controller, management, and safety functions. A

very close cooperation with internal partners and external partners led to a successful commissioning

of the whole vehicle combination. Finally, the trailer was successfully registered with the HoD-system

installed. This paved the way for the start of public road testing (see Figure 8).

Figure 6: Schematic plan view of the TRANSFORMERS trailer with the locations of important

components

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Figure 7: EMG, cardan shaft, and drive axle mounted in the trailer

Figure 8: TRANSFORMERS combination during public road testing

Drive Axle

Cardan

Shaft

Gearbox

and EMG

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4.1 Clutch operation

One important aspect during the commissioning of the HoD driveline was the correct operation of the

dog clutch, which can decouple the EMG from the drive axle. Due to the use of a dog clutch, there is

no slip between input and output once the clutch is closed. Nevertheless, before closing it, a certain

slip is required to make sure that the claws of the input and output shaft are not staying face to face

all the time preventing the clutch closing. Hence, the clutch handling is quite complex.

Figure 9 shows real world torque and speed measurement data of the HoD trailer driveline while

driving. EMG speed and EMG torque is plotted against the time while performing a clutch closing

process. The EMG speed control mode is activated after t=68.4 s, which adjusts the EMG speed to the

desired slip in the clutch. In the next step, the control mode is switched to torque control and the

clutch is closed approx. at 69.2 s. Shortly after the EMG speed matches the wheel speed of the driven

axle, which means that the clutch successfully closed. Now the actual driving or braking torque could

be applied, which is not shown in this figure. For safety reasons the maximum torque of the speed

controller was limited. Further optimization of the clutch closing process including the speed controller

has the potential of reducing the closing time significantly.

This diagram also shows that all driveline components are working together properly in the vehicle

combination.

Figure 9: Speed and torque measurements during a clutch closing process in the moving

vehicle during commissioning

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4.2 Brake blending

In order to maximize the recuperation potential the EMG needs to be used for braking as much as

possible. So two modes of braking are possible:

1. Pure electric braking: This mode provides the highest recuperation potential. With an

additional switch/lever/function, the driver can activate the braking of the EMG separately

from all other braking devices on the truck. Furthermore, Volvo integrated pure electric

braking into the trucks engine brake controller.

2. Brake Blending: For braking with the service brakes a brake blending functionality was

implemented by Knorr Bremse in the trailer.

The brake blending functionality was developed together with Knorr-Bremse. Its basic principle is

sketched in Figure 10. The trailer receives a target deceleration (shown in green) via the EBS

communication with the truck. This target deceleration is always fulfilled by the EBS. It uses the EMG

(Share Retarder in blue) as much as possible. If the currently applied torque by the EMG is not

sufficient, the EBS adds the friction brakes (shown in red) to an extent necessary to fulfill the target

deceleration. If the EMG capability is reduced, e.g. when the SoC reaches high levels, the friction

brakes take over the whole braking power. In case of ABS events, the EMG is switched off

immediately and the standard ABS algorithm is applied to the friction brakes only.

Figure 10: Schematic operation of the trailer brake blending5

5 B.Meurer, R. Klement, B. Queckenstedt, J. Harder and M. Mederer, “E-mobility entering semitrailers –

new requirements and impact on future semitrailer brakes” in XXXIV International µ-Symposium Brake

Conference, Bad Neuenahr, 2015

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4.3 On-road testing

After successful commissioning of all subsystems, test drivers performed first test runs on closed

tracks in preparation for the public road testing. The focus was the safety and controllability.

Therefore, test drivers checked the vehicle behavior and stability by several handling tests like e.g.

full EMG braking and propulsion, jack-knifing and functional tests of the implemented safety measures

as well as performance tests under normal operating conditions. These tests successfully proved the

stability of the vehicle and the proper functioning of the HoD driveline as a whole.

The results paved the way for public road testing and the registration of the semitrailer with the HoD

system installed.

Figure 11 shows measurement results of a test run of about 300 km. It shows the usage of the EMG

for braking and driving on an undulating highway road. The driving torque is limited to 50% of the

maximum torque to achieve a longer assistance for the ICE. For higher vehicle speeds the braking

torque also does not reach the full torque anymore, because of the power limitation of the EMG.

Figure 11: Measurement data of a 300 km test run on public road

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Figure 12 shows a driving detail from the above full test cycle. The driver demands propulsion torque

(shown in blue) from the ICE. This triggers the clutch closing process as shown above. After

successful closing of the clutch, the EMG applies torque to the driven trailer axle (shown in green).

When no torque shall be applied by the EMG anymore the clutch opens to minimize the drag torque at 𝑡 ≈ 60 𝑠 and 𝑡 ≈ 120 𝑠.

Figure 12: Closer look on activation and deactivation of the driving torque of the EMG

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Figure 13 shows a braking scenario from the above test cycle during a downhill slope. Again a

retarder braking torque request to the EMG (shown in red) triggers closing of the clutch before

actually applying the EMG torque (shown in green). Intermediate releases of the braking request do

not instantaneously trigger the clutch to open again. The torque request needs to remain zero for a

certain time before opening the clutch.

Figure 13: Closer look on activation and deactivation of the braking torque of the EMG

The above real world measurement figures show the successful operation of the HoD driveline system

in the trailer together with the TRANSFORMERS trucks. All systems work as planned also for long test

cycles of more than 300 km.

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5 Conclusions

This chapter summarizes the conclusions drawn from the first-time implementation of a HoD

framework compliant hybrid mission adaptable driveline. The first section presents the key findings in

general. The second section provides a set of interface signals for the HoD framework that proved to

be sufficient for a successful and safe HoD system operation.

5.1 General Findings

The TRANSFORMERS project developed a concept for a mission-adaptable hybrid drivetrain for long-

haulage applications. The key feature is an electric drivetrain that is completely integrated in the

trailer instead of the truck. The project proofed the feasibility of this approach not only from a

technical but also from a homologation point of view.

Besides the technical implementation of the intended approach, the homologation for public road use

was a key challenge. This is mainly because current regulations and safety standards do not cover

electric drivelines within trailers or semitrailers.

A key issue is ECE R13, which currently does not allow selective braking of individual trailer axles,

because electric/recuperative wear-free braking is not considered for trailers. In contrast, braking of

individual truck axles is allowed, e.g. with the retarder or engine brake.

TRANSFORMERS proposes that ECE R13 should to be modified. In order to enable the maximum

recuperation potential of the HoD approach it should be allowed to apply individual brake forces to the

axles of a vehicle combination to a certain extent. This would pave the way for pure electric braking

as well as energy optimal brake blending. In theory, these two functions are able to foster the whole

recuperative braking potential available before engaging the energy wasting friction brakes. From a

safety perspective, no stability issues were identified during the test drives with the TRANFORMERS

system configuration and component sizing. Nevertheless, it might be necessary to limit or control the

torque at the wheels in order to ensure the driving stability. This is a question for further research

especially if more powerful EMGs are used in the trailer.

The implementation showed that a Case A compliant semitrailer can be applied to legacy/standard

trucks with reasonable efforts. In principle, only a gateway is required that provides a small set of

signals to the trailer already available in modern trucks. Hence, TRANSFORMERS proved that

retrofitting solutions are possible in principle even without defining new communication interfaces.

Figure 14 shows the final proposal for a mission adaptable modular HoD system that could be applied

in near future. This proposal already supports the installation of several ESUs and EMGs while the

interface to the truck potentially remains unchanged.

HoD Signal RoutingEnergy FlowExisting InterfacesScope of Framework

VCU

Truck EBS

Trailer EBS


ISO11992-2

EMGn EMGn EMGn

ESUn

ESUn

EMG-Interface

ESU-Interface

Gate-way

VCU-Interface(ISO11992-3)

TDMSwith TEMS

Figure 14: Proposed HoD system architecture for Case A

Nevertheless, Case B is the most promising approach for the future. A holistic and predictive vehicle

energy management system (VEMS) would be able to consider all available drivetrain components

and auxiliaries to minimize the overall energy consumption. This approach is hardly feasible with the

existing truck-trailer interfaces – namely ISO11992. According to the HoD framework Case B needs a

new high-bandwidth interface with appropriate signal and message definitions for implementation.

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The advantage of the HoD framework proposal is that only a new high-bandwidth VCU interface needs

to be designed. All other interfaces can be implemented as described for Case A. Figure 15 shows the

final TRANSFORMERS proposal of a Case B modular mission-adaptable HoD drivetrain.

HoD Signal RoutingEnergy FlowExisting InterfacesScope of Framework

VCUwith

VEMS

Truck EBS

Trailer EBS


ISO11992-2

EMGn EMGn EMGn

EMG-Interface

Gate-way

VCU-Interface(new)

TDMS

ESUn

ESUn

ESU-Interface

Figure 15: Proposed HoD system architecture for Case B

Besides these key findings, TRANSFORMERS summarizes further knowledge gain as follows:

The implementation phase proved that the HoD framework already provides reasonable

interfaces to EMG and ESU. A series application could require a more detailed and extended

specification. Nevertheless, the framework has the potential to support the development of

framework compliant components in future and can serve as a starting point for an industrial

standardization process.

The successful system integration of the HoD trailer with two trucks from different OEMs –

Volvo and DAF – proofed the interoperability of the proposed drivetrain concept. Every truck

that implements a HoD framework compliant VCU interface is potentially able to benefit from

the HoDD. Hence, it is possible to create a distributed hybrid drivetrain by coupling a

conventionally propelled truck with a HoD trailer.

It is feasible to integrate a high performance electric drivetrain in a semitrailer. The packaging

is challenging but easy compared to hybrid drivetrains completely integrated in trucks. In

particular it is possible to find significant space for the ESU beneath the trailer, which would be

challenging in a hybrid truck.

The EMC laboratory measurements showed that the HV system installation is compliant to

current regulations and requirements. Since the installation considered basic EMC rules and

HV installation guidelines, the HoD vehicle combination passed the EMC test at the first

attempt.

Even though the HoD Case A can operate without any man-machine-interface (MMI) it could

be necessary to provide some information to the driver. The demonstrator displays several

signals (see Error! Reference source not found. in section 5.2) in order to support the test

engineers with status and performance information. TRANSFORMERS concludes that this topic

needs further investigations, e.g. in follow-up projects like AEROFLEX.

In principle, the HoDD enables pure electric driving for the vehicle combination. Tests proofed

the feasibility. Further investigations are required for future implementation. Currently,

TRANSFORMERS assumes that only Case B can provide this feature since this feature requires

additional signals to be sent from truck to trailer that are currently not available in ISO 11992.

Dedicated test drives proved that at least one trailer axle can be propelled safely assuming the

performance parameters of the demonstrator driveline. For example, it was not possible to

jack-knife the combination. It must be investigated if this statement holds true for drivelines

with higher performance as well.

Since the TDMS mechanically disconnects the HoDD in all driving stability events (ESP, ABS

intervention, etc.) the system does not influence the vehicle stability by its operation.

Brake manufacturers can adapt their EBS and provide a break-out CAN interface that

transmits the necessary data originally sent from truck to trailer based ISO11992 part 2. This

is important since ISO11992 part 2 defines a point-to-point connection between truck and trailer EBS, which prohibits connecting other devices.

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Brake manufacturers are able to implement brake blending based on the EBS interface

described in the HoD framework. The project proved the feasibility of two braking strategies.

The first one evenly distributes the driver brake request among the three trailer axles and is

completely in line with current regulations. The second one is significantly more efficient since

it uses recuperative braking at the HoD axle to a maximum possible extent before applying

the service/friction brakes. Even though the second strategy recuperates more energy, current

regulations in principle do not cover different/selective brake torques at the trailer. Since this

is a requirement for the trailers service brake, there is a legal grey area if it comes to

recuperative braking devices.

5.2 HoD-Framework

During the commissioning of the HoD vehicle combinations, it was not necessary to refine key ECU

functionalities defined by the HoD framework. Nevertheless, the initial interface definitions required

several additional signals.

Especially in the trailer, some control functions can be located in different ECUs resulting in design

freedom for the electric driveline in the trailer. For example, the clutch control can be part of the EMG

system or the TDMS. While the first option enables a better functional encapsulation, the second

option is more flexible in terms of energy management and optimization. For the control functions in

question further investigations are needed to determine the best solution. This still could change the

signals of the involved interfaces. The changes are expected to be rather small, and straightforward

to implement.

The HoD-Framework is going to be used and refined in the follow-up project AEROFLEX. Furthermore,

it is planned to make the framework available to EUCAR and trailer manufacturer associations.

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5.3 Lessons Learnt

Subsequently, this section summarizes the lessons learnt during the course of the project:

Integrating a battery in a semitrailer is comparably easy. The integration of a HoDD is a

challenge especially because of:

o unavailable key components like light weight driven trailer axles,

o construction changes and regulatory constraints (current regulations do not really

allow pure electric braking). It is questionable if suitable and affordable components

and regulation are available in near future.

A reasonable alternative would be to install the battery on the trailer and the e-driveline into

the truck. OEMs develop e-drivelines for trucks anyhow. This approach would ease the

packaging problem, reduce the overall system complexity and costs (fewer electronic devices),

and is expected to be in line with current regulations. The downsides are

o a robust HV connection between truck and trailer needs to be established

o the trailer does not provide a driven axle that could improve traction capabilities e.g.

on slippery roads

If traction on the trailer is not a key feature for the customer, the recuperated energy could be

used for powering, e.g. trailer cooling units or providing energy for hotel functions like heating

venting and air conditioning during resting times. This would result in a significantly smaller

ESU. The power rating and size of the EMG is expected to be smaller as well. Further

investigations are necessary for a business case investigation.

The HoD framework proposes slim interfaces for ESUs and EMGs. If these could be

standardized, the market introduction of compatible devices can be accelerated. This holds for

the HoD distributed driveline but also for hybrid drivelines completely installed in the truck.

Current regulations do not consider recuperative braking in trailers. Efforts should be put into

adapting mainly ECE R13 in order to enable innovative recuperation solutions. Pure e-braking

at single axles is the most critical point since it enables a significantly higher recuperation

potential (approx. factor 3-5).

For safety and efficiency reasons (drag torque) TRANSFORMERS disconnects the EMG

mechanically by means of a clutch. It would be very interesting to investigate solutions that do

not need this clutch, e.g. by using a separately excited electric machine. Such solutions would

result in lower costs, less complexity, less weight while maintaining the safety of the system.

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6 Acknowledgment

This project is co-funded by the 7th FP (Seventh Framework

Programme) of the EC - European Commission DG Research

http://cordis.europa.eu/fp7/cooperation/home_en.html

http://ec.europa.eu

PROJECT PARTICIPANTS:

VOLVO VOLVO TECHNOLOGY AB(SE)

BOSCH ROBERT BOSCH GMBH

DAF DAF TRUCKS NV

FEHRL FORUM DES LABORATOIRES NATIONAUX EUROPEENS DE RECHERCHE ROUTIERE

FHG FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E.V

IFSTTAR INSTITUT FRANCAIS DES SCIENCES ET TECHNOLOGIES DES TRANSPORTS, DE

L'AMENAGEMENT ET DES RESEAUX

IRU IRU PROJECTS ASBL

P&G PROCTER & GAMBLE SERVICES COMPANY NV

SCB SCHMITZ CARGOBULL AG

TNO NEDERLANDSE ORGANISATIE VOOR TOEGEPAST NATUURWETENSCHAPPELIJK ONDERZOEK (NL)

UNR UNIRESEARCH BV (NL)

VEG VAN ECK BEESD BV

VIF KOMPETENZZENTRUM - DAS VIRTUELLE FAHRZEUG, FORSCHUNGSGESELLSCHAFT MBH

DISCLAIMER

The FP7 project has been made possible by a financial contribution by the European Commission under Framework Programme 7. The Publication as provided reflects only the authors’ view.

Every effort has been made to ensure complete and accurate information concerning this document.

However, the author(s) and members of the consortium cannot be held legally responsible for any mistake in printing or faulty instructions. The authors and consortium members retrieve the right not to be responsible for the topicality, correctness, completeness or quality of the information provided. Liability claims regarding damage caused by the use of any information provided, including any kind of information that is incomplete or incorrect, will therefore be rejected. The information contained on this website is

based on author’s experience and on information received from the project partners.


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