Electric drive system for new energy vehicles

Abstract

The invention discloses an electric drive system for a new energy vehicle. The electric drive system includes a high voltage power battery, a direct current supporting capacitor, a first Y capacitor, a second Y capacitor, a motor controller, a three-phase alternating current motor, a first capacitor protection device, and a second capacitor protection device, the direct current supporting capacitor is connected with a positive electrode and a negative electrode of the high voltage power battery in parallel, two input ends of the motor controller are connected with two ends of the direct current supporting capacitor in parallel, three output ends are connected with three-phase input lines of the three-phase alternating current motor, a housing of the three-phase alternating current motor is directly in a lap joint with the vehicle body ground, the first Y capacitor and the first capacitor protection device are connected in series between the positive electrode of the high voltage power battery and the vehicle body ground, and the second Y capacitor and the second capacitor protection device are connected in series between a negative electrode of the high voltage power battery and the vehicle body ground. According to the electric drive system for the new energy vehicle in the invention, when a short circuit occurs between a winding of a phase of the motor and the housing or an insulation failure occurs, the Y capacitor in the electric drive system can be protected, and a filtering effect of the Y capacitor is not affected.

Description

technical field [0001] The invention belongs to the technical field of new energy vehicles, and in particular relates to an electric drive system for new energy vehicles. Background technique [0002] Safety capacitors are used in such occasions, that is, after the capacitor fails, it will not cause electric shock and will not endanger personal safety. [0003] According to IEC60384-14, safety capacitors are divided into two types: X capacitors and Y capacitors. X capacitors are capacitors connected across the two lines (L-N) of the power line, and metal film capacitors are generally used; Y capacitors are connected across the power lines respectively. The capacitance between the two lines and the ground (L-E, N-E) generally appears in pairs. Based on the limitation of the leakage current, the value of the Y capacitor should not be too large. Generally, the X capacitor is uF level, and the Y capacitor is nF level. The X capacitor and the Y capacitor are used in the power f...

AI Technical Summary

Problems solved by technology

However, the above-mentioned high-voltage electric drive system has the following faults in practical applications: When the motor is running and the motor controller is in the normal working mode, at this time one of the three phases (UVW three-phase) of the motor (U or V or W phase) suddenly Short circuit to ground, because the upper system or the motor controller cannot detect a short circuit fault of the motor relative to the ground during the operation of the motor, and cannot stop the motor, resulting in an abnormally large current flowing through the Y capacitor, causing severe heat and eventually causing the short circuit damage of the Y capacitor

[0006] To sum up, the existing high-voltage electric drive system for new energy vehicles has the following problems: 1). When the high-voltage electric drive system is working, it is impossible to diagnose a motor relative to the body or insulation failure through the upper system or the motor controller itself. Fault; 2). When a fault occurs with respect to the motor body or insulation failure, there is no effective Y capacitor protection measure, which eventually leads to short circuit damage to the Y capacitor

Images