PUMBAA Electric Vehicle Motor Controller Unit (MCU) PMC20A

(1) Energy conversion function. Realize braking energy recovery to improve vehicle range; 

(2) Torque execution function. The controller sends negative torque values to the motor controller to reduce energy waste; 

(3) Active discharge function. Large-capacity capacitor self-discharge for a long time will have high-voltage safety risks; 

(4) Safety protection function. Motor system with fault detection, fault reminding, fault handling and other safety protection functions; 

(5) High-speed CAN network communication function. Effective realization of the electric motor control unit and the whole vehicle function strategy, control the safe and reliable operation of the motor system to ensure the safe operation of the vehicle.

In new energy vehicles (NEVs), the Motor Control Unit (MCU), also known as an "inverter" or "electric control system," is one of the "three core components" (battery, motor, and electric control system). Its performance directly determines the vehicle’s driving experience, energy consumption, and reliability. The MCU’s primary function is to precisely convert the high-voltage direct current (DC) output from the power battery into the three-phase alternating current (AC) required by the drive motor. It also adjusts the motor’s speed and torque based on commands from the Vehicle Control Unit (VCU), thereby controlling the vehicle’s acceleration, deceleration, and constant-speed operation. Its working principle can be broken down into four core processes: "signal reception – energy conversion – motor driving – status feedback."

1. Signal Reception: Receiving Vehicle Control Commands

During vehicle operation, driver inputs (e.g., accelerator pedal position) are first transmitted to the VCU. The VCU calculates the target torque/speed required by the motor based on parameters such as accelerator pedal opening, vehicle speed, battery state of charge (SOC), and gear position. It then sends this command to the MCU via the Controller Area Network (CAN) bus.

2. Energy Conversion: Converting DC to AC

The power battery outputs high-voltage DC (typically 300V–800V), while NEV drive motors (predominantly permanent magnet synchronous motors) require three-phase AC to operate. This conversion is performed by the MCU’s "inverter circuit," centered on a "three-phase bridge inverter circuit" composed of six IGBTs (Insulated Gate Bipolar Transistors) – two per phase (upper and lower bridge arms). Each IGBT acts as a "controllable switch." The MCU’s main control chip outputs PWM (Pulse-Width Modulation) signals to precisely regulate the turn-on/off timing and duty cycle of the six IGBTs. For example, turning on the upper bridge arm IGBT of Phase A while turning off the lower bridge arm, and turning on the lower bridge arm IGBT of Phase B while turning off the upper bridge arm, forms a current loop between Phases A and B. By cyclically controlling the conduction sequence of the IGBTs in Phases A, B, and C, the MCU generates adjustable three-phase AC (with frequency determining motor speed and amplitude determining torque).

（MCU）

3. Motor Driving: AC Powering Motor Operation

The three-phase AC generated by the inverter circuit is directly input into the stator windings of the drive motor. The current flowing through the stator windings creates a rotating magnetic field, which drives the rotor to rotate under electromagnetic force. This converts electrical energy into mechanical energy, which is then transmitted to the wheels via the reducer and drive shaft, ultimately propelling the vehicle.

4. Status Feedback: Closed-Loop Control and Safety Protection

The MCU does not merely "issue commands once"; it employs a closed-loop control mechanism of "sensor data collection → feedback adjustment" to ensure the motor operates as intended while preventing faults. Current sensors collect real-time phase currents, voltage sensors monitor bus voltage, and temperature sensors track IGBT and motor temperatures. The main control chip compares "actual current/speed" with "target current/speed." If deviations occur, it adjusts the IGBTs’ PWM signals in real time to correct the AC output parameters, stabilizing torque and speed. If abnormal signals (e.g., excessive current, over-temperature IGBTs) are detected, the MCU triggers protective measures such as reducing output power, cutting off IGBT output, or reporting faults to the VCU, preventing damage to the motor or MCU and ensuring driving safety.

(MCU)

Conclusion​

The NEV MCU is a sophisticated system integrating power electronics, microelectronics, control theory, and thermal management technologies. As an intelligent inverter, it uses vector-controlled closed-loop algorithms to precisely regulate the switching of power semiconductors (IGBTs/SiCs), converting battery DC into controllable AC to drive the motor and enabling efficient energy recovery. Rapid advancements in MCU technology – such as the evolution from IGBTs to higher-efficiency SiC materials – have enabled modern NEVs to achieve exceptional acceleration performance, smooth driving experiences, and extended range.