Q:
Hello, Teacher Xiong! During the maintenance of electric vehicles, I found that a fault in the high voltage controller alone can cause the vehicle to fail to start, lack of power while driving, warning lights to illuminate, and charging abnormalities. Could you please explain why a fault in the high voltage controller can lead to so many failure phenomena?
Reader from Hunan: Liu Bin
A:
The high voltage controller for electric vehicles is shown in Figure 1. The functions of the high voltage controller are as follows.
1. Control the on/off of high voltage electricity. The high voltage direct current after the onboard charger boosts and rectifies is sent to charge the high voltage battery through the high voltage controller. If there is a problem with the high voltage controller, it can cause charging failures in the vehicle.
2. The power from the high voltage battery must pass through the high voltage controller to supply power to the motor. If the high voltage controller fails and cannot supply power, the vehicle will fail to start. If there is poor contact in the high voltage controller, the vehicle will experience a lack of power while driving.
3. Regulate power distribution. The high voltage controller can distribute the high voltage output from the battery to different high voltage devices as needed, such as the air conditioning compressor and heater, to ensure that each device receives the appropriate amount of power. If there is a problem with the high voltage controller, it can also cause failures in the air conditioning and heating systems.
4. Implement energy recovery management. During the vehicle’s deceleration or braking process, the high voltage controller coordinates components like the motor to convert the vehicle’s kinetic energy into electrical energy and recover it to the battery, reasonably controlling the recovered power, voltage, and other parameters to enhance the vehicle’s energy utilization efficiency and increase the range. If there is a problem with the high voltage controller, it may also lead to energy recovery failures in the vehicle.
5. Fault monitoring and protection. The high voltage controller monitors various parameters of the high voltage system in real-time, such as voltage, current, and temperature. Once it detects abnormal conditions, such as overvoltage, overcurrent, or overheating, it will quickly take corresponding protective measures, such as cutting off the circuit or using different warning lights for high voltage, insulation, and power to indicate faults, preventing further damage to the high voltage system and ensuring the safety of passengers.
6. Collaborate with vehicle control strategies. The high voltage controller works in conjunction with the vehicle controller to precisely regulate high voltage electricity according to established driving modes, speed requirements, etc. Since the high voltage controller mainly contains fuses and controllers, if they are damaged, the vehicle may also exhibit abnormal current sounds or ignition sounds as faults.
Xiong Ronghua
Visiting professor in automotive engineering at several universities, technical support for the Wuyi chain of auto repair, expert in automotive performance judicial appraisal and arbitration, special expert for programs such as Traffic Broadcasting 92.7 and Private Car Broadcasting 107.8, Yilian Driving Assistant, and Himalaya FM Xiong Gong’s Lecture Hall, dedicating his life to automotive fault diagnosis and repair, and is known in the industry as the “Automotive Hua Tuo”.