The high-voltage system of an electric vehicle is the core of the vehicle’s power drive. It is responsible for the storage, transmission and conversion of high-voltage electric energy, and directly supplies power to high-power components such as the vehicle drive and air conditioning heating. Its performance directly determines the vehicle’s power performance, safety and driving range.
In my understanding, the high-voltage system is mainly divided into five sections: power battery, drive system, charging system, air conditioning system and high-voltage power distribution system. We will elaborate on them as follows:
I. Power Battery (BAT)
- Function: Stores electric energy and provides power for the vehicle.
- Features: High energy density, long service life; lithium-ion battery is the most common type.
II. Drive System
Drive Motor (M)
- Function: Converts electric energy into mechanical energy to drive the vehicle.
- Features: High power, high torque and high efficiency; common types include permanent magnet synchronous motors and AC asynchronous motors.
Motor Control Unit (MCU)
- Function: Controls motor operation and adjusts speed and torque.
- Features: High efficiency and precision, ensuring stable motor operation.
III. Charging System
On-Board Charger (OBC)
- Function: Converts alternating current (AC) to direct current (DC) to charge the battery.
- Features: High efficiency, compatible with multiple charging standards.
DC-DC Converter
- Function: Converts high-voltage direct current to low-voltage direct current for the low-voltage system.
- Features: High efficiency and stability, ensuring normal operation of the low-voltage system.
IV. Air Conditioning System
PTC Heater
- Function: Provides warm air for the cabin and heats the battery.
- Features: High efficiency and fast response, improving winter comfort and battery performance.
Electric Compressor
- Function: Provides cooling for the air conditioning system and dissipates heat for the power battery and high-voltage components.
- Features: Directly driven by high-voltage electricity, enabling efficient operation even when the vehicle is stationary.
Notably, most current models adopt heat pump air conditioners, which replace the traditional PTC heater, reducing energy consumption while improving efficiency.
V. High-Voltage Power Distribution System (BDU)
- Function: Distributes high-voltage electric energy and protects the circuit.
- Features: Integrates multiple protection functions to ensure system safety.
All high-voltage components are connected by high-voltage cables to form the complete vehicle high-voltage system. This energy distribution hub is the BDU high-voltage power distribution box.
