How To Find Heat Transfer In An Electric Car?

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  Mike said,

  Draw a diagram that shows the flow and conversion of energy in the car. Where ever energy is transferred or converted from one form to another, some energy is converted to waste heat that must be transferred to the atmosphere.
  Electrical power is connected to a battery charger inside the car. The charger converts the power from AC to DC at the voltage required to charge the batteries. Perhaps 2 to 3 percent of the energy is lost as heat in the electronic components in the charger and transferred to aluminum heatsinks and from the heatsinks to the air.
  Inside the batteries, electrical energy is converted to chemical energy. That conversion and the flow of current through internal resistance in the batteries results in heat that must be transferred to the air. When the car is running, chemical energy stored in the batteries is converted to electrical energy with a similar transfer of waste heat – perhaps 3 to 6%.
  DC power from the batteries is converted to AC power in the motor controller. The motor controller regulates the voltage and frequency to control the speed of the motor. Perhaps 3 to 4 percent of the energy is lost as heat in the electronic components in the motor controller and transferred to aluminum heatsinks and from the heatsinks to the air.
  The AC motor converts electrical energy to mechanical energy. Perhaps 5 to 6 percent of the electrical energy is lost as heat in the motor and transferred to the air.
  Some mechanical energy, perhaps 1%, is lost as heat in the bearings and gears of the mechanical transmission, differential, drive shafts and wheels.
  When the brakes are applied, some braking energy is returned to the batteries with losses in the drive train, motor, motor controller and batteries. There are also disk brakes that convert mechanical energy through friction to heat in the disks from which the heat is transferred to the air.
  I have provided estimates of the percent of energy transferred as heat from various components. Only the designers can provide accurate calculations.
  PS1:
  There is more information at teslamotors.com and the links below. If you want more details about the losses in the energy storage system, power electronics module, motor etc., post another question or use answers email. The energy storage system US patent is 7433794.

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