The Technology: How it works
CONTROL SYSTEM
The mechanical simplicity of the EV powertrain is somewhat offset
by an increased complexity on an electronic level. Therefore, the
electric vehicle's control system is the most complex and important
part of the EV, and controls the operation of the vehicle. The
control system receives signals from various components like the
motor, the pedals, and the battery and processes the information
and sends out a signal to drive the car. These calculations must
be accomplished in milliseconds, so, like a computer, the control
systems have a microprocessor. While no two control systems are
identical, the feedback signals from the various components are
similar. The table below should give you some idea of the information
the control system is responsible for.
|
Component
|
Feedback Signal
|
|
Electric Motor(s)
|
Winding temperature
|
| |
Rotor Speed (RPM)
|
|
Battery
|
Voltage
|
| |
Output Current
|
| |
Temperature
|
|
Motor Controller
|
Current (and direction of current)
|
| |
Voltage
|
| |
Temperature
|
| |
Leakage Current
|
|
Accelerator Pedal
|
Voltage as a function of pedal position
|
|
Shift Selector
|
FWD/REV
|
| |
Range Selection
|
Table courtesy of http://www.etvi.org/High_Tech/New_Electric_HiTech_right.html
The control system continuously monitors the feedback signals
so the car runs smoothly and does not malfunction. If the pedal
is pressed, the microprocessor will know to increase the current
to the motor and the car will go faster. If the processor realizes
the temperature is too hot, it can limit the output of the motor
or just shut down the motor. Overall, the control system is needed
to maximize energy in the battery, prevent unsafe conditions from
occurring, and allow the vehicle to run smoothly.
AC Motor Controller 
source
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Source: http://www.etvi.org/High_Tech/New_Electric_HiTech_right.html
Source: http://rqriley.com/ev-tech.html
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