Energy Procedia 56 ( 2014 ) 591 – 597

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1876-6102 © 2014 Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).Peer-review under responsibility of COE of Sustainalble Energy System, Rajamangala University of Technology Thanyaburi (RMUTT)doi: 10.1016/j.egypro.2014.07.197

11th Eco-Energy and Materials Science and Engineering (11th EMSES)

Study of Power Generation for Permanent Magnet Motor Elevator by Energy Regenerative Unit (EERU)

0 Boonyang Plangklang F*, Sittichai Kantawong Department of Electrical Engineering, Faculty of Engineering,

Rajamangala University of Technology Thanyaburi, Klong 6, Thanyaburi, Pathumthani 12110

Abstract

This paper presents Power Generation for Permanent Magnet Motor Elevator by Energy Regenerative Unit (ERU). The study reveals that permanent magnet motors with rated 5.5 kW in elevators which is working by transferring mechanical energy into electricity when the motor is rotating without power therefore the motor is capable of producing electrical energy back into the grid system. This situation is call “Regenerative mode” which is the wasted energy can be used once again [1]. The study is done by simulation using MATLAB/Simulink program. This investigated ERU and inverter in this study can be applied for future use of in existing elevator system. The Proposed ERU is used to convert DC voltage to AC voltage for gird synchronization. The investigated ERU is operating as three-phase module. From experiment, it is observed that when the motor operates as a generator then ERU will receive DC voltage from the elevator inverter system then convert to AC voltage that can be fed into the grid system. © 2014 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of COE of Sustainalble Energy System, Rajamangala University of Technology Thanyaburi (RMUTT).

Keywords: power generation for elevator, regenerative, ERU ;

* Corresponding author. Tel.:+66-2-549-3420 ; fax: +66-2-549-3422.

E-mail address: boonyang.p@en.rmutt.ac.th.

© 2014 Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).Peer-review under responsibility of COE of Sustainalble Energy System, Rajamangala University of Technology Thanyaburi (RMUTT)

592 Boonyang Plangklang and Sittichai Kantawong / Energy Procedia 56 ( 2014 ) 591 – 597

1. Introduction

Currently vehicle lift is important in vertical transport of building, tower, shopping mall, office buildings and factories, normally part of a building will have an elevator. Elevator equipment is regarded as a very major consumption machine. Therefore, if the elevator can generate electric energy to the system, this can reduce energy consumption thus elevator system can be an important device for the conservation of energy. [3]

This paper will study of Power Generation for Permanent Magnet Motor Elevator by Energy Regenerative Unit (ERU). The paper will describes the functions and components of the elevator system, principle of 4 Quadrant, principle of DC boost converter, Equations of the permanent magnet motor, and principle of speed control in section 2, the simulation of the system with Matlab/Simulink in section 3, the results in section 4 and conclusions in section 5.

2. Theory and Implementation

2.1 System of Elevator Typically, the structure of the elevator system is composed of 6 main components as shown in Figure 1 [1].

1. Control System 2. Electric Motor 3. Sheave 4. Counterweight 5. Guide Rails 6. Passenger Car

Figure 1, Components of the elevator system. [4] Figure 2, The comparison between the various state motor speed and torque.

2.2 Principles of Four – Quadrant Operation Figure 2 shows a graph of the speed and torque control in both the positive and negative directions. From figure

2, progress in Quadrant 1,3 are defined as motor mode which means that the speed and torque is in the same direction. The progress in Quadrant 2,4 are assigned to be a generator, sometimes called regenerative mode. The regenerative mode to work on a permanent magnet motor in the elevator system is rotating without power. Or cause braking of the motor is able to produce electricity for the elevators are located on the elevator. Load must be less than the weighted pendulum and as the elevator to load than gravity pendulum. Both cases rely on the force of gravity pulling the motor rotation. Without using electrical energy drive to elevator. Can be divided according to the mode of operation of the elevator system has the following Table 1.

Boonyang Plangklang and Sittichai Kantawong / Energy Procedia 56 ( 2014 ) 591 – 597 593

Table 1. Operation of the elevator system mode

Elevator Load > Counterweight Load < Counterweight

Up 1. Using Energy 2. Using Gravity

Down 3. Using Gravity 4. Using Energy

2.3 Principles of DC Boost Converter

A boost converter (step-up converter) is a DC-to-DC power converter with an output voltage greater than its

input voltage.By the appearance of a Boost Converter looks as shown in Figure 3.

Figure 3, dc boost converter circuit

Equations (1) - (4) Switch on

dt

tdiLvv LinL

)( [V] (1)

min,0

1)( L

DT

inswL IdtvL

DTisw

[A] (2)

Switch off

dt

tdiLvvtv LoinL

)()()( [V] (3)

sw

sw

T

DTLoinswL Idtvv

LTi max,)(1)( [A] (4)

ov = Output Voltage [V]

inv = Input Voltage [V]

Lv = Inductor Voltage [V] LI = Inductor Current [A] D = Duty Cycle swT = Switching Time

594 Boonyang Plangklang and Sittichai Kantawong / Energy Procedia 56 ( 2014 ) 591 – 597

Braking

chopper

DC

AC

ControllerSpeed

Controller d/dt

Car

Three-phase

Diode rectifier

PMSM

Inverter

Inverter Converter

Grid

380V3ph

Speedreference

ERU

Permanent Magnet

Synchronous Motor (PMSM)

Figure 4, Operating power generation controller for permanent magnet motor elevator

2.4 Permanent Magnet Synchronous Motor

The characteristics of the permanent magnet motor according to equations (5) - (8), which is applied to test the program in MATLAB/SIMULINK

qrd

qd

dd

d

d ipLL

iLRv

Ldtdi 1 (5)

q

rdr

q

dq

Lp

ipLL

iqLqRvq

Lqdtdi 1 (6)

qdqdqe iiLLipT )(5.1 (7)

)(1mre

r TFTJdt

d (8)

Where: qd LL , be Inductance of the d and q [H]

R be Resistance of Stator [ ]

qd ii , be current of d and q [A]

qd VV , be voltage of d and q [V]

r be angular velocity of the rotor [rad/s]

be magnetics flux of motor [Wb] p be number of pole pairs

Boonyang Plangklang and Sittichai Kantawong / Energy Procedia 56 ( 2014 ) 591 – 597 595

eT be electromagnetic torque [Nm]

mT be shaft mechanical torque [Nm]

J be combined inertia of rotor and load [kg/m 2] F be combined viscous friction of rotor and load [N]

Figure 5, Energy Regenerative Unit (ERU) by Matlab/Simulink

2.5 Principle of Speed Control Using a PI Controller The system will measure the speed of the motor that is compared with speed Reference, the response of the

system is controlled by a PI controller. Therefore, the design of PI controller system is very important part. The PI controller is designed and to find the parameters Kp and Ki for this simulation, both the Software Tool GUI, a tool called SISOTOOL in Matlab/Simulink is used to help in the transfer function as follows. [1]

s

KKsPI ip1 ( 9 )

3. Simulation of the System

In this paper, a simulation system of Power Generation for Permanent Magnet Motor Elevator by Energy Regenerative Unit is done by Matlab/Simulink, from Figure 4, 5, input section of motor drive, set. Rectifier series are used to flow power in one direction. The generated power is restored back to the system grid when the motor works as a generator [2]. When motor works as a generator, the ERU serves to convert the voltage from the DC Bus to AC using IGBT.

596 Boonyang Plangklang and Sittichai Kantawong / Energy Procedia 56 ( 2014 ) 591 – 597

Figure 6, Input Voltage of ERU

Figure 6 is the simulation results of Vdc. Before entering the ERU when the voltage is increased under generating mode can be restored to grid. When elevator finished its generating mode and begin to motor, the ERU will stop its feedback and enter idle mode.

Figure 7, Output Voltage and Power of ERU Figure 7 is the graph of the simulation result of the three-phase power and voltage output of the ERU. Negative

power represents the power back to Grid. As Figure 4, ERU serves to convert the DC voltage to three phase AC voltage.

Time

Voltage

540Vdc

Generating mode

Motoring mode Po

wer

(W)

Vol

tage

(V)

Time

-13kW

380VW

Boonyang Plangklang and Sittichai Kantawong / Energy Procedia 56 ( 2014 ) 591 – 597 597

4. Results

By simulation program using Matlab/Simulink of power generation for permanent magnet motor elevator by energy regenerative unit. The results of the simulation are shown in Table 2.

Table 2. Parameter on ERU

Input of ERU (DC Bus)

Output of ERU

Power 3Ø Voltage 3Ø

530 - 540 Vdc 13kW 380 Vac

From table 2 shows the input voltage of ERU from regenerative of permanent magnet synchronous motor and the

output. The DC voltage output from the inverter is the input of ERU, and then transferred to DC boost converter device that converts voltage DC to AC. The output voltage of the ERU is characterized by square wave and finally through a series of filtering therefore the voltage waveform is sine wave, after this point we can be connected to grid system.

5. Conclusions

ERU is a concept that can be connected to the existing elevator system using permanent magnet motors. This investigated ERU can be applied for future use of existing elevator system. They are able to generated electric output energy from the elevator when the elevator motors work force of gravity therefore ERU will receive DC voltage from the elevator’s inverter system then converts to AC voltage therefore this power can be fed into the grid system. Thus power output can be fed back to the system for replacement of the energy that has been used.

References [1] Thanit Punprayoong and Boonyong Plangklang , energy saving elevators by in Building a case study:

RMUTT, Conference on Energy Network of Thailand 8. 2-4 May 2555, Maha Sarakham : 4, 2555. [2] H. Inaba, S. T. Nara, H. Takahashi$M. Nakazato, High speed elevators controlled by current source inverter system with sinusoidal input and output [3] http://www.danahermotion.com/education_training/motor/four-quadrant operation (August, 2012). [4] Rajamangala of Physics, Department of Physics Faculty of Science Rajamangala, University of Technology

Thanyaburi. [5] Pirote Brikapkul., The design of the feedback controller in integral self-adjusting for permanent magnet

synchronous motors, Master degree thesis, Electrical Engineering, KMUTNB Thailand, 2546. [6] Ashok B.Kulkarni , Hien Hguyen and E.W.Gaudet “A Comparative Evaluation of line Regenerative and

Non-Regenerative Vector Controlled Drives for AC Gearless Elevator” ,IEEE 1431 – 1437 [7] Masaki Nomura , Hiroyu Ikejima , Shigetaka Morita and Eiki Watanabe, Regenerative Power Control For

VVVF Motor Drive (Critical Braking Method Applied To The Elevator) , IEEE 97 – 105