An electric compressor consists of a frequency converter, a motor, and a compressor. The frequency converter converts the direct current (DC) power supplied by a high-voltage battery into alternating current (AC) power and sends it to the motor to drive its rotation. The compressor is a scroll compressor, directly connected to the motor. The motor directly controls the compressor's operation. Because the frequency converter and motor generate high temperatures during operation, the compressor is equipped with a cooling structure that utilizes the intake refrigerant for cooling.

The electric compressor system comprises several precision components, including the motor as the power source, which drives the internal rotor of the compressor to compress the refrigerant. High-voltage connectors and interlocking devices ensure a safe and reliable connection to the high-voltage power supply (typically 350V DC), which is fundamental to the normal operation of the electric compressor. Simultaneously, the system is also equipped with a low-voltage connector to provide a stable 12V power supply to the control module, and a 0V ground connection to ensure circuit stability and safety.

New energy vehicles typically use electric scroll compressors, which mainly consist of a housing, an electronic control unit, a motor stator and rotor, a rotating turbine disk, and a fixed turbine disk (as shown in the diagram below). The rotating and fixed turbine disks rotate to form several crescent-shaped cavities, which constitute the intake, compression, and exhaust chambers of the scroll compressor, respectively. For an electric scroll compressor with three pairs of crescent-shaped cavities, each cycle includes one intake port, one intake chamber, one compression chamber, one exhaust port, and one exhaust chamber.

(1) Advantages

1) High efficiency and reliability. The intake, compression, and exhaust processes are continuous and unidirectional. There is no gas leakage during the piston compression stage, and the shaft seal uses a low-friction flexible mechanism.

2) Simple structure and compact size. The volume is 40% of that of a piston compressor, and the weight is 85% of that of a piston compressor.

3) High volumetric efficiency. Due to the absence of an intake valve, the gas is continuously compressed in multiple chambers, resulting in high volumetric efficiency, making it particularly suitable for variable speed motors.

4) Low starting torque, low noise, and low vibration. The two spiral grooves in a pair of scroll plates can simultaneously compress multiple crescent-shaped spaces, i.e., continuous multi-cavity compression, in which multiple cycles of different phases occur simultaneously, with one peak coinciding with the next trough. Therefore, the change in drive torque is minimal, and the compressor operates smoothly. Because exhaust gas is continuously discharged, mechanical impact and airflow pulsation of the exhaust valve are almost nonexistent, resulting in a noise level 3-5 decibels lower than other types of compressors. Moving parts undergo extremely small circular motions with low inertia, leading to minimal vibration.

In the control of the electric compressor, the control module integrates a CAN bus interface, enabling the electric compressor to communicate with other electronic systems in the vehicle in real time and receive control commands. CAN-H and CAN-L lines serve as the high and low level lines of the CAN bus, respectively, for transmitting control signals and data to ensure coordinated operation between systems.

Furthermore, this electric compressor system is equipped with a 5V/PWM interlock device, further enhancing system safety. The PWM (Pulse Width Modulation) signal is used to adjust the compressor's speed and power to adapt to different operating conditions. The 5V signal provides a stable voltage reference, ensuring the interlock device can accurately determine the high-pressure connection status, preventing accidental compressor start-up in case of incorrect connection, thus avoiding potential safety hazards.

Although the working principle of the electric compressor is relatively complex, it is extremely efficient. When the motor drives the internal rotor of the compressor, the refrigerant is compressed in the compression chamber, changing from a low-pressure state to a high-pressure gas. Then, the high-pressure gas flows through the condenser and is cooled, becoming a high-pressure liquid. The liquid then passes through the expansion valve to reduce pressure and enter the evaporator, absorbing heat from the vehicle's interior to achieve a cooling effect. Throughout the process, sensors and the control system monitor the refrigerant pressure and temperature in real time, adjusting the motor speed and compressor operation based on the monitoring results to ensure the air conditioning system operates efficiently and stably.