Motor Control System Description - Components
PCU
The inverter, the DC-DC converter, and the motor control module are located in the power control unit (PCU). It contains a cooling system composed of a dedicated radiator, PCU electric coolant pump, and expansion tank. This cooling system enables temperature adjustment inside the PCU.
The motor control module controls the traction motor and the generator motor, and communicates with the PCM to coordinate with the engine and transmission operation.
The motor control module contains a rewritable ROM and uses an updating tool to enable the latest program updates.
Traction Motor/Generator Motor
The traction motor is located in the transmission (e-CVT). It produces driving force and generates power for the high voltage battery.
The generator motor is also located in the transmission (e-CVT). It recharges the high voltage battery and generates power for engine startup.
Each motor is a lightweight, compact, and highly efficient three phase synchronous motor. It is positioned together with the gear unit in the transmission (e-CVT).
The motor consists of a three coil stator secured in the housing, and a rotor with permanent magnets in its outer circumference.
A motor rotor position sensor is also located in the transmission (e-CVT). It detects the position of the press-fitted motor rotor position rotor, to determine the rotor's rotation position (phase).
The stator coil utilizes distributed winding to reduce vibration and enable stable torque during high speed operation.
DC-DC Converter
To maintain the 12 volt system voltage, the system uses a DC-DC converter. The DC-DC converter converts high voltage direct current into low voltage direct current with little energy loss.
The temperature of the DC-DC converter is monitored by the motor control module built into the PCU, and in case of an abnormal rise of the temperature, the motor control module stops the operation of the DC-DC converter, which causes the 12 volt charging indicator to come on. The operation of the DC-DC converter also stops when an abnormality with the input voltage or output voltage is detected; this causes the 12 volt charging indicator to come on, and a warning is displayed on the multi-information display.
When the DC-DC converter stops operation because of an abnormality, there will be an insufficiency of 12 volt power, which restricts the output of the electric powertrain system, according to the output drop of the 12 volt battery.
Cooling System
The PCU cooling system is a water cooling system consisting of a dedicated PCU electric coolant pump, radiator, expansion tank, coolant hose/pipe, and PCU.
Coolant water absorbs heat from the water jacket inside the PCU, passes through the radiator interior and releases heat to the atmosphere.
The PCU electric coolant pump adopts a 12 volt DC brushless water pump, and has a built in motor and ECU.
PCU Coolant Flow