Pulse Width Modulation Electric Vehicle DC Motor Controller · Electric Vehicle DC Motor...
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P P ulse ulse W W idth idth M M odulation odulation Electric Vehicle Electric Vehicle DC Motor Controller DC Motor Controller Eric Rodda Eric Rodda – – AEVA Adelaide AEVA Adelaide - - October 2010 October 2010
Transcript of Pulse Width Modulation Electric Vehicle DC Motor Controller · Electric Vehicle DC Motor...
PPulse ulse WWidth idth MModulationodulationElectric VehicleElectric Vehicle
DC Motor ControllerDC Motor Controller
Eric Rodda Eric Rodda –– AEVA Adelaide AEVA Adelaide -- October 2010October 2010
For this example we will assume that For this example we will assume that the Electric Vehicle has a totalthe Electric Vehicle has a total battery battery voltage of 120 Voltsvoltage of 120 Volts and also that the and also that the
accelerator pedal mechanically accelerator pedal mechanically connects to aconnects to a potboxpotbox which in turn which in turn
electrically connects to theelectrically connects to the controllercontroller..
PPulse ulse WWidth idth MModulationodulationElectric VehicleElectric Vehicle
DC Motor ControllerDC Motor Controller
For this example we will assume that For this example we will assume that the Electric Vehicle has a totalthe Electric Vehicle has a total batterybatteryvoltage of 120 Voltsvoltage of 120 Volts and also that the and also that the
accelerator pedal mechanically accelerator pedal mechanically connects to aconnects to a potboxpotbox which in turn which in turn
electrically connects to theelectrically connects to the controllercontroller..
PPulse ulse WWidth idth MModulationodulationElectric VehicleElectric Vehicle
DC Motor ControllerDC Motor Controller
Image courtesy of EV Works -
Western Australia
POTBOX
DC MOTOR CONTROLLERDC MOTOR CONTROLLER
TheThe controllercontroller uses sophisticated control uses sophisticated control circuitry and power output stages circuitry and power output stages (MOSFET or IGBT) which takes the high (MOSFET or IGBT) which takes the high voltage from the traction battery pack and voltage from the traction battery pack and converts it into variable width pulses, converts it into variable width pulses, controlled by the controlled by the potboxpotbox, and then sends , and then sends these pulses to the drive motor.these pulses to the drive motor.
PWMPWM
PulsePulse--Width Modulation Width Modulation is a very is a very efficient way of providing efficient way of providing intermediate amounts of electrical intermediate amounts of electrical power between fully off and fully on.power between fully off and fully on.
DUTY CYCLEDUTY CYCLE
The termThe term duty cycleduty cycle describes the describes the proportion ofproportion of onon time to the regular time to the regular interval orinterval or periodperiod of time; a low duty of time; a low duty cycle corresponds to low power, cycle corresponds to low power, because the power is off for most of the because the power is off for most of the time. Duty cycle is expressed in percent, time. Duty cycle is expressed in percent,
100% being fully on.100% being fully on.
PWM FrequencyPWM Frequency
TheThe frequencyfrequency of operation of a DC Motor of operation of a DC Motor Controller is generally above the audio Controller is generally above the audio
spectrum and often aroundspectrum and often around 22Khz22Khz
(22,000 cycles per second) giving a period (22,000 cycles per second) giving a period of approx 45uS.of approx 45uS.
PWM in ActionPWM in Action
TheThe following slides show five progressing following slides show five progressing stages of the accelerator position. stages of the accelerator position. Of course, in real life, this process will be Of course, in real life, this process will be continuous and smooth from one stage to continuous and smooth from one stage to the nextthe next……
VO
LTS
TIME
120
0
What the motor sees
Foot off accelerator pedal Foot off accelerator pedal –– PotboxPotbox at rest positionat rest position
VO
LTS
TIME
120
0
One Period with a Duty Cycle of approx 15%
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What the motor sees
Foot on accelerator pedal Foot on accelerator pedal –– PotboxPotbox partly openpartly open
VO
LTS
TIME
120
0
One Period with a Duty Cycle of approx 50%
60
What the motor sees
Foot on accelerator pedal Foot on accelerator pedal –– PotboxPotbox half openhalf open
VO
LTS
TIME
120
0
One Period with a Duty Cycle of approx 75%
90
What the motor sees
Foot on accelerator pedal Foot on accelerator pedal –– PotboxPotbox open moreopen more
VO
LTS
TIME
120
0
One Period with a Duty Cycle of 100% What the motor sees
Accelerator pedal to floor Accelerator pedal to floor –– PotboxPotbox fully openfully open
PPulse ulse WWidth idth MModulationodulationElectric VehicleElectric Vehicle
DC Motor ControllerDC Motor ControllerEric Rodda Eric Rodda -- AEVA October 2010AEVA October 2010
You are now all experts in this You are now all experts in this subjectsubject……
PPulse ulse WWidth idth MModulationodulationElectric VehicleElectric Vehicle
DC Motor ControllerDC Motor ControllerEric Rodda Eric Rodda -- AEVA October 2010AEVA October 2010
Any QuestionsAny Questions……
