Power Detection and Analysis of EV/HEV Inverters and Motor Drive Systems

The three core components of new energy vehicles are the battery, motor, and electronic control system. The motor drive control system is the primary execution component during the vehicle's operation, and its drive characteristics determine the main performance indicators of the vehicle. It is a crucial part of electric vehicles. The motor drive system mainly comprises the motor, power converter, controller, various detection sensors, and power supply. Compared to traditional industrial motors, the drive motors for new energy vehicles have higher technical requirements.

EV/HEV Inverters and Motors

A test platform built with the high-precision current sensor AIT-600SI, mechanical energy sensors, and power analyzers can accurately measure and evaluate the power drive system of electric vehicles. The high-precision current sensor transmits the battery output signals and the inverter input/output signals to the power analyzer, forming a power measurement unit for precise power measurement and analysis. At the same time, the speed and torque sensors can measure the mechanical energy of the drive motor, creating a motor measurement unit.

Shown in Figure 2, the battery pack of the electric vehicle provides a DC power source for the entire motor drive control system. The DC is converted into three-phase AC by the inverter to supply power to the motor, which drives the bearings to rotate and move the electric vehicle. The motor controller receives feedback signals such as motor speed and relays them to the instrument. When braking or accelerating, the controller adjusts the frequency of the inverter to achieve the desired acceleration or deceleration.

The high-precision current sensor No. 1 （from left to right）measures the battery pack's voltage, current, and other electrical parameters. Sensors No. 2, 3, and 4 measure the electrical parameters of the inverter's output. The torque sensor measures the shaft power of the motor. The test system composed of sensors No. 1 and 2, 3, and 4 is used to measure the inverter's efficiency, while sensors No. 2, 3, 4, and the motor measurement system are used to measure the motor's efficiency.