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IN the past EVs used DC motors/controllers because they operate with the battery’s current without lots of complicated electronics. Now that these electronics are getting better and better lost of EVs use AC motors/controllers due to lighter weight and better efficiency
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Controllers:
The controller is the electronics that operate between the batteries and the motor to control the speed/acceleration
Regulates energy flow from the battery
For ac motors it transforms the battery’s direct current into alternating
Controller converts the motor to generator(regenerative braking)
Reverses motor rotation so car can reverse
Modern controllers change speed and acceleration by a process called pulse width modulation
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Rated power of motor is calculated from the combination of speed, torque and duty cycle; this establishes critical voltage, current, and capacity requirements of battery
Battery discharge current rating should meet or exceed motor current input requirements
Battery discharge curve is important because output voltage directly affects output speed of motor
https://auto.howstuffworks.com/electric-car3.htm
General info:
Typical motor: 20 000 watt-30 000 watt range
Typical controller: 40 000-60 000 watt range – eg a 96 volt controller will deliver a max of 400-600 amps
https://www.danatm4.com/blog/10-things-consider-choosing-electric-motor/
Things to consider when choosing a motor:
Vehicle Characteristics:
Size
Weight
Aerodynamic
These determine speed, torque and power requirements of electric motor
2. Driving cycles
Lots of stops/ vs long distances with only a few stops
Use to determine battery pack size, series/parallel
3. Maximum Speed:
Targeted max speed, how long does it need to be sustained
Rolling radius of wheel
4. Maximal torque:
need to know if car will be ascending very high angles
Can calculate highest torque required by ev considering gearbox(do electric vehicle’s even use a gearbox?)
5. Max power:
need to take into account drag, friction coefficients
peak power of electric motor cannot be sustained continuously, need to take time constraints into consideration(the car won’t need to climb the worst hill for the entire drive)
6. Battery Capacity
7. Battery Voltage:
Normally two ranges of voltages: 300-450 Vdc and 500-750V dc
Voltage limitations of IGBT(Insulated Gate Bipolar Transistors) used in motor controller and there are two main standard voltages available for them: 600V dc and 1200V dc