High-reliability high-voltage high-current electromechanical servo driver

Abstract

Disclosed is a high-reliability high-voltage high-current electromechanical servo driver. A peak voltage generated between a collector electrode and an emitting electrode in a turn-off process of an IGBT can be effectively suppressed; meanwhile, a peak value of a fluctuation voltage caused by overhigh bus inductance after the peak voltage also can be suppressed, thereby ensuring the high reliability of the electromechanical servo driver, wherein after an IGBT driving circuit receives a low-level input, the IGBT driving circuit outputs a certain intermediate voltage between plus 14.5V and plus 7V for a certain while instead of directly outputting a minus 8V level to turn off, for example, the IGBT driving circuit outputs plus 9V and then outputs minus 8V to turn off. Due to the fact that current of the collector electrode of the IGBT is in direct proportion to the turn-on voltage of a gate pole, the plus 9V door pole level limits the current of the collector electrode of the IGBT to be a relatively low value; and therefore, when the driving circuit outputs minus 8V to turn off the IGBT consequently, the generated current change rate is not too high, namely, the suppression to the peak voltage is realized, and the safety of the IGBT is protected.

Description

technical field [0001] The invention relates to a servo driver, in particular to a high-reliability high-voltage and large-current electromechanical servo driver, which belongs to the technical field of electromechanical servo drivers. Background technique [0002] The electromechanical servo system for aerospace vehicles mainly includes four parts: servo power supply, servo control driver, servo motor and servo mechanism, among which the servo driver is used to drive the servo motor. At present, servo drives generally use a three-phase full-bridge main circuit to drive the motor, and the three-phase full-bridge circuit is realized by a power device IGBT module. [0003] With the improvement of the electromechanical servo power level, the operating voltage and three-phase current of the electromechanical servo driver are constantly rising. In aerospace applications, the current maximum operating voltage of the servo driver reaches 400VDC, and the phase current can reach 200A...

AI Technical Summary

Problems solved by technology

The problem with such a design is that the parallel snubber capacitor can be used to suppress the peak voltage, but due to the existence of the snubber capacitor, a fluctuating voltage will be generated after the peak voltage is formed between the CE electrodes of the IGBT, and the peak value of the fluctuating voltage where L DC is the stray inductance of the bus circuit, Cs is the capacitance value of the absorbing capacitor, i c is the phase current. For high-current servo drives used in aerospace, the bus cable is usually longer, resulting in a larger loop inductance L DC larger, and i c It is also relatively large, and the peak value of the fluctuating voltage formed will also be high, which will form a continuous impact on the IGBT, and in severe cases, cause the IGBT to be damaged by overvoltage, which is not conducive to the highly reliable operation of the system

[0005] In addition, in the existing IGBT drive circuit, the turn-off method is direct turn-off, that is, after the drive circuit receives the input PWM turn-off signal, it immediately outputs the turn-off signal at the output terminal. The electrode current change rate is very large, which has little effect on low-power servo control drivers, but it will reduce reliability for high-voltage and high-current servo control drivers

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