By: Mark Bright and Mike Donaldson

By:Mark Bright

and Mike Donaldson

Advisor:Dr. Gary Dempsey

Project Goal System Applications Thermal Plant Overview

Engine Side Thermal Side

The goal of our Engine Control Workstation is to simulate thermal environments that are found in liquid-based cooling systems.

With this system we created several different control methods via MATLAB and Simulink working together to control both the engine and thermal transient and steady state responses.

Car Application PC Application

The overall goal of this project is to protect the motor with varying loads with minimum energy usage

Engine Side

Circuitry

Thermal Side

Circuitry

Engine DSP Board

Thermal

DSP Board

Generator

Thermistor

Flowmeter

Pump

Pittman

Motor

Cooling Blocks

Pittman Motor

Tmax = 311 deg F

Thermal impedance 75.9 deg F/watt

(2.9 A)^2 * (3.91 ohm) = 36 watts

36W * (75.9 deg F/watt) = 2732 deg F

Engine Control:

Minimize C-code and execution time

Learn Auto-Code generation platform of Simulink/DSP interface

Design software for PWM generation and velocity calculation from rotary encoder.

Design closed-loop controllers for velocity and acceleration control.

32 bit Processor

150 MHz Clock

16 A/D Channels

12 PWM Digital I/O Channels

128K on-chip Flash Memory

9 Ports Total

3.3v Supply

Interfaced to PC by serial port

Inputs and output go through level-shifter IC (5v to 3.3v / 3.3v to 5v)

User Interaction:Set RPM and

Gain

System Design Simulink Model

MATLAB GUI

Code Composer Auto Code Generated

C Code

TI 2812 DSP Board

PWM Output to Drive Motor

Both encoder channels from the Pittman motor are offset from each other

Pulses are wired into the DSP board Port 8 – pins 6 and 7

2 counts can be obtained per period for each channel – 4 times as many counts

Allows for Steady State Error of ± 5 RPM

Simulink codes this as inner shaft RPM, which must be converted to outer shaft RPM – 5.9:1 gear ratio

Drag QEP Block into Simulink diagram to implement

Data sent to GUI is set here

Model is used to generate Code Composer C code

P, PI, and FF Control Implemented
















Desired RPM

Actual RPM

Controller Output

PWM Duty Cycle

Simulation model started where the 2008 mini project left off

Bilinear Transform converted analog controllers to digital controllers


Gp = ______________ (s/146+1)(s/776+1)

______________

(s/146+1)

(s/1460+1)17.1FF=Gp =

17.1 -1

Simulation: 596 RPM input FF Output is 17 RPM Impulse duration was 2mS

Actual: 596 RPM input FF Output is 17 RPM As expected from

simulation

100 RPM Step Input

FF Control decreases response time by 20 mS

Less overshoot

Smaller time to first peak

FF Compensation

PI Control Only

RPM vs Time (ms) plot

Start, Type “guide” in MATLAB

GUI can be designed here with many components

Once designed, MATLAB creates an .m file and .fig file

MATLAB GUI Design

GUI created in MATLAB and interfaced to Simulink Model

Plots Motor RPM, PWM Duty Cycle, Transient Response, and both PI and Feed Forward Controller Output

User can input desired RPM: 0 to 834 RPM

Optimal controller gains loaded at startup, but user can control both the gain and type of control

GUI updates in real time

numMsgsOchan1 = r.msgcount('ochan1');

if (numMsgsOchan1)

speed = r.readmsg('ochan1', 'int32');

end


if (numMsgsOchan2)

pid = r.readmsg('ochan2', 'int32');

end


if (numMsgsOchan3)

RPM = r.readmsg('ochan3', 'int32');

end


if (numMsgsOchan4)

PI_Out = r.readmsg('ochan4', 'int32');

end


if (numMsgsOchan5)

FFOut = r.readmsg('ochan5', 'int32');

end

if ((numMsgsOchan1 ~=0) && (numMsgsOchan2 ~= 0) && (numMsgsOchan3 ~= 0) && (numMsgsOchan4 ~= 0) && (numMsgsOchan5 ~= 0))

axes(handles.axes3);

plot(handles.axes3,x_axis1, RPM);

title(handles.axes3,'Measured speed of the Motor');

xlabel(handles.axes3,'t (s)');

ylabel(handles.axes3,'Speed (RPM)');

grid(handles.axes3,'on');

axis(handles.axes3,[0 5 1 850]);

axes(handles.axes4);

cycle = double(pid);

plot(handles.axes4,x_axis1, cycle);

title(handles.axes4,'Duty Cycle of the PWMWaveform');

xlabel(handles.axes4,'t (s)');

ylabel(handles.axes4,'Duty Cycle (%) ');

grid(handles.axes4,'on');

axis(handles.axes4,[0 5 1 100]);

Acceleration Control

◦ Adjustable Feed Forward control with different types of input commands: combos of ramps, steps, and parabolic. Load changes can simulate hills and different road conditions.

CAN Bus Interface

◦ Use the DSP board’s CAN bus to send data between the boards. This would allow for a main GUI to control both sides of the system.

Data Logging Feature

◦ Allow for a user to tune controllers and compare results. Could implement a new EE431 / 432 homework or design project around the system.

Set Control Points for Thermal and Engine Response

◦ Set desired temperature for a change in the coolant as well as a engine RPM governor based on load conditions

Variable Resistance

Anti-aliasing filter

Use PWM to drive Pump/Fan

Interface from digital to analog

Average Voltage seen by the device

Opto-Isolator

TIP120 choice

Design for 3A Opto-Isolator

LPF to ‘DC’ the PWM

Ideal Op Amp theory

Voltage @ Input = Voltage @ Pump

Opto-Isolator

Conversion of A/D Value to Temperature

Excel Trendline


Excel Trendline


Excel Trendline


Excel Trendline

Datatype conversions

Function auto-code generated

Datatype conversions

Function auto-code generated

Bang – Bang

Improved Bang Bang

P Control

PI Control

Fan PWM %

Pum

p P

WM

%

0 10 20 30 40 50 60 70 80 90 10060

65

70

75

80

85

90

95

100

-5.5

-5

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

Pum

p P

WM

%

Fan PWM%

Supervisory Control

Further improvement by utilizing Pump and Fan cooling efficiencies

Faster PID Control

Use of more temperature sensors

Use of CAN bus

Nick Schmidt◦ Case Assembly◦ Hardware Assembly

Dr. Dempsey◦ Case Assembly◦ Hardware Assembly

Plant Wc is at 899 rad/sec

P Control System Wc was at 164 rad/sec

Gain = .08

Phase Margin with P control:◦ 115

Gp = __________________ (s/146+1)(s/776+1)

17.1

Gp(s) =K * 1/(Tc(s)+1) * e^-(s)Td

Pump/Plant ◦ K = (-.8 degrees F / 6.4 V)◦ Tc = 20◦ Td = 6

Fan/Plant◦ K = (-9.6 degrees F / 13V)◦ Tc = 12◦ Td = 15

Thermal Transfer Functions

Control Toolbox Results P-Pump

◦ Wc = .148 radians PM = 105 GM =22.1dB

P-Fan◦ Wc = ? PM = undefined GM =29.4dB

PI-Pump◦ Wc = .39 radians PM = -139 GM =16.1dB

P-Pump◦ Wc = .0966 radians PM = -48 GM =-15.92dB

OCHAN’s allow for data to be outputted to:◦ GUI◦ Workspace

PWM Brush Type Servo Amplifer – Model 10A8DD

Protected for over-voltage and over-current

DC Supply Voltage: 20-80v

Peak Current: ±10A Maximum Continuous

Current: ±6A

Documents

By: Mark Bright and Mike Donaldson