Compensation voltage algorithm of inverter dead zone in motor control system and interpolation method

Abstract

The invention discloses a compensation voltage algorithm of an inverter dead zone in a motor control system and an interpolation method. The compensation voltage algorithm calculates the inverter dead zone effect error time Terr, equivalent error time Tave caused by conduction and voltage reduction of a power transistor and a diode in one PWM cycle is included, U-phase output end voltage error Vao_err caused by the Tave equivalent error time in one PWM cycle is calculated, three-phase voltage error of the inverter is thus obtained, and the compensation voltage of the inverter dead zone is obtained by the phase voltage error. According to the interpolation method, through sampling three-phase current of the inverter and carrying out filter processing by a current sensor, clark conversion, park conversion, inverted park conversion and inverted clark conversion are respectively carried out on the three-phase current after filter, three-phase current signals after filter are obtained, a zero-crossing threshold is set, and inverter compensation voltage interpolation can be carried out when the absolute value of the three-phase current is more than the threshold. With the algorithm, the compensation voltage can be obtained, and by adopting the interpolation method, the inverter dead zone effect can be avoided.

Description

technical field [0001] The invention relates to a compensation voltage algorithm and an interpolation method for an inverter dead zone in a motor control system. Background technique [0002] When the motor is running at low speed, especially at light load, the phase current and phase voltage are distorted due to the dead zone effect of the inverter and zero current clamping phenomenon occurs, which increases the current harmonic content of the inverter output; this current harmonic The content increases the flux linkage distortion and torque ripple of the motor. In the current motor control system, before the space vector pulse width modulation (SVPWM) control, how does the inverter get the accurate three-phase voltage U A , U B , U C In order to avoid the dead zone effect of the inverter, there are mainly the following methods: simply use the PID adjustment control to directly adjust the i d i q Perform pi adjustment to get u d , u q , and then through inverse park ...

AI Technical Summary

Problems solved by technology

[0002] When the motor is running at low speed, especially at light load, the phase current and phase voltage are distorted due to the dead zone effect of the inverter and zero current clamping phenomenon occurs, which increases the current harmonic content of the inverter output; this current harmonic The content increases the flux linkage distortion and torque ripple of the motor

In the current motor control system, before the space vector pulse width modulation (SVPWM) control, how does the inverter get the accurate three-phase voltage U A , U B , U C In order to avoid the dead zone effect of the inverter, there are mainly the following methods: simply use the PID adjustment control to directly adjust the i d i q Perform pi adjustment to get u d , u q , and then through inverse park transformation and inverse clark transformation to get U A , U B , U C ; but this method cannot fully compensate the error voltage caused by the dead zone effect of the inverter. The reasons include the following points: First, due to the limitation of the software or hardware of the motor control system, the current sampling has a certain bandwidth, and the adjustment speed is limited. Secondly, current regulation is a delay or first-order link, and the frequency domain expression of current PI regulation is usually k p is the proportional coefficient of the PID regulator, k i is the integral coefficient of the PI regulator, T s is the sampling time, z is a complex variable, transplanting the pull-type transformation of the sampling signal to represent the z-transformation of the discrete-time signal, and the influence of the current regulation speed, so that the inverter dead zone effect cannot be fully compensated

Images