Discharging method, system and device of bus capacitor for power device

Abstract

The invention relates to the technical field of power electronics, in particular to a discharging method, system and device of a bus capacitor for a power device and a vehicle and aims to solve the technical problem how to effectively and reliably perform active discharging on the bus capacitor. The method provided by the invention mainly comprises the following steps of controlling one of an upper bridge arm and a lower bridge arm to be maintained in an on state, and controlling the other one of the upper bridge arm and the lower bridge arm to be alternatively switched on and switched off, wherein a direct-connection current of a half-bridge circuit during direct connection is dependent on a control pole voltage of a weak switch-on bridge arm. According to the steps, no extra circuit structure is arranged in the power device; short-time direct connection for many times is performed by controlling the half-bridge circuit, and electric energy of the DC bus capacitor can be gradually released; and meanwhile, the direct-connection time of the half bridge circuit is controlled by adjusting a duty ratio of the control pole voltage of a power semiconductor device, and the problem that discharging is out of control can be effectively solved.

Description

Technical field [0001] The present invention relates to the field of power electronics technology, in particular to a method, system and device for discharging bus capacitance of a power device. Background technique [0002] The electric drive system (EDS) of a new energy vehicle usually has a high-capacitance bus capacitor (such as a bus capacitor of hundreds of microfarads or more). When the main relay of the power battery is disconnected, more residual charge will remain on the bus capacitor and its capacitor voltage is equal to the output voltage of the power battery. The output voltage of the power battery is often as high as hundreds of volts (for example, between 250V and 450V). In order to avoid the high voltage on the bus capacitor from causing harm to the human body, it is necessary to discharge the bus capacitor immediately after the main relay is disconnected. [0003] The discharge method of the bus capacitor mainly includes a passive discharge method and an active di...

AI Technical Summary

Problems solved by technology

The active discharge method using the motor winding mainly uses the equivalent resistance of the motor winding to consume the electric energy in the bus capacitor. When the discharge is out of control, the motor may generate unexpected motor torque, which is potentially harmful.

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