Vector controller of alternating current asynchronous motor

Abstract

The invention relates to a vector controller of an alternating current (AC) asynchronous motor. The vector controller comprises a control chip, a drive circuit, a three-phase inverter circuit, a Hallsensor and an amplifying and filtering circuit, and is characterized in that a PWM output hardware interlock circuit is connected between the control chip and the drive circuit, and the IGBT overflowing signal of the drive circuit is fed back to the PWM output hardware interlock circuit; a stator current overflowing signal generation circuit is connected with the output end of the amplifying and filtering circuit of a current sampling circuit in parallel, and a stator current overflowing signal is fed back to the PWM output hardware interlock circuit; and a temperature sensor is additionally arranged at the bottom of an IGBT module, a signal thereof is input to the A / D port of the control chip, and the general input / output ports of the control chip are utilized to control the operation of a radiator fan. The invention can effectively realize under-voltage protection and current overflowing protection on the IGBT module, and achieves the functions of IGBT soft turn-off and motor stator current overflowing protection.

Description

technical field [0001] The invention belongs to the field of power devices, in particular to the protection of the IGBT module of the vector frequency conversion speed regulation system of the AC asynchronous motor of the electric vehicle. technical background [0002] The main components of the AC asynchronous motor vector controller are: the motor, the inverter and the battery pack. The internal structure of the IGBT module is the inverter bridge, which is the core of the inverter. The length of its service life directly affects the service life of the entire controller, and the cost of the IGBT module accounts for two-thirds of the inverter. [0003] There are several difficulties in designing the IGBT drive circuit: [0004] 1) When the IGBT module works for a long time, it will emit a lot of heat, which will cause the IGBT to be overheated and damaged. [0005] 2) The size of the gate forward drive voltage will have an important impact on the circuit performance and m...

AI Technical Summary

Problems solved by technology

When the forward drive voltage increases, the on-resistance of the IGBT decreases, which reduces the turn-on loss; but if the forward drive voltage is too large, the short-circuit current IC increases with the increase of UGE, which may cause the IGBT to appear Latching effect, resulting in gate control failure, resulting in damage to the IGBT; if the forward drive voltage is too small, the IGBT will exit the saturated conduction region and enter the linear amplification region, causing the IGBT to overheat and damage

[0006] 3) Generally speaking, the IGBT can withstand a maximum of 2 times the rated current within 10μS, but if it is often subjected to overcurrent, the device will age prematurely. Therefore, when the IGBT is overcurrent, use the soft turn-off method to keep the gate voltage between 2μS-5μS Dropping to zero voltage within a short period of time, because the di / dt will be very large due to the instantaneous blockage of the gate voltage, a high peak voltage will be generated at both ends of the IGBT, which is very easy to damage the IGBT

[0007] 4) When the inverter is running, when the motor stator current is over-current, it will not only affect the service life of the motor or even burn out the motor, but also affect the service life of the IGBT module

However, the module series of most domestic manufacturers are cheap, but the soft shutdown, current overcurrent and voltage undervoltage protection functions are not complete; while foreign module series have complete functions, often expensive

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