Electric vehicle and high-voltage system and high-voltage discharge circuit thereof

Abstract

The invention discloses an electric vehicle and a high-voltage system and high-voltage discharge circuit thereof. The high-voltage discharge circuit comprises a discharge unit, a discharge drive unit,and a discharge control unit. The discharge unit consists of a discharge switch tube and a discharge resistor that are connected in series between a positive terminal and a ground terminal of a high-voltage bus of an electric vehicle. The discharge drive unit is used for outputting a discharge driving signal to the discharge switch tube, so that the discharge switch tube is connected or disconnected repeatedly. The discharge control unit is used for receiving a discharge control signal and transmitting the discharge control signal to the discharge drive unit, so that the discharge drive unitdrives the discharge switch tube actively to enable the discharge unit to carry out discharging actively. According to the high-voltage discharge circuit, the electric energy is bled by using the variable resistance region of the discharge switch tube, so that the discharge efficiency is improved; and the high-voltage system of the electric vehicle can work or carry out discharging normally, so that the high-voltage safety of the electric vehicle is improved.

Description

technical field [0001] The invention relates to the technical field of electric vehicles, in particular to an electric vehicle high-voltage discharge circuit, a high-voltage system of the electric vehicle and an electric vehicle with the high-voltage system. Background technique [0002] With the popularity of electric vehicles, people have higher and higher requirements for the safety of electric vehicles in high-voltage environments. The high-voltage system of electric vehicles is composed of battery packs, high-voltage relays, film capacitors, motor controllers, DC / DC converters, high-power permanent magnet synchronous motors, etc. In order to reduce the fluctuation of power voltage and the interference of power supply to high-voltage devices, film capacitors are added at both ends of the power bus. When the power supply is cut off, the bus voltage will not drop below the safe voltage soon because of the existence of film capacitors. Therefore, in order to protect the sa...

AI Technical Summary

Problems solved by technology

However, these two types of active discharge methods also have disadvantages: first, whether the discharge is controlled by a logic circuit or by a motor controller, once the low-voltage power suddenly disappears, the active discharge will fail, making it difficult to discharge the high-voltage power; other 2. During the high-speed driving stage of the vehicle, the motor controller works in the electric state. If it needs to be actively discharged for some reasons (for example, the key switch is turned OFF or the vehicle collides, etc.), the motor speed is very high at this time, and the counter electromotive force is large. When the motor controller changes from the motoring state to the power generation state for active discharge, there will be the possibility of IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor) overvoltage or overcurrent, and there is a greater risk

However, the passive discharge resistor is always discharging during normal driving and charging, resulting in energy loss. At the same time, the loss generated by the passive discharge resistor and the discharge speed are contradictory. If the discharge speed is pursued, the selected value of the passive discharge resistor is small. This leads to increased energy loss

[0005] According to the above analysis, the current discharge technology, whether it is active discharge or passive discharge, has its imperfections, which brings hidden dangers to the safety of use and maintenance of electric vehicles.

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