Compensation method and device for motor control system and its DC bus voltage

Abstract

The invention discloses a motor control system, and a compensation method and a compensation device of direct current bus voltage of the motor control system. The motor control system comprises a rectifying circuit, an electrolytic capacitor, an inverter circuit and a voltage sampling circuit used for sampling the direct current bus voltage. The compensation method comprises the following steps of acquiring frequency of an alternating current input power supply; calculating a phase deviation generated during sampling of the voltage sampling circuit according to the frequency of the alternating current input power supply; and compensating the direct current bus voltage according to the phase deviation to control the inverter circuit according to the compensated direct current bus voltage. Therefore, an influence of a ripple wave on motor control can be eliminated by compensating the direct current bus voltage; precise control on a motor can be realized; and stepout outage of the motor can be effectively avoided.

Description

technical field [0001] The invention relates to the technical field of motor control, in particular to a method and device for compensating DC bus voltage in a motor control system, a motor control system and household appliances. Background technique [0002] As inverter air conditioners have become the mainstream of the market, inverter washing machines and refrigerators have also rapidly entered thousands of households. Among them, there are various control schemes for the inverter compressor in the inverter refrigerator, for example, a sine wave control method based on motor control engine. However, when the motor control system does not have a PFC (Power Factor Correction, power factor correction) circuit, the DC bus voltage rectified and filtered by the rectifier circuit and the electrolytic capacitor will carry a ripple that is twice the frequency of the AC input power supply. Such as Figure 1a and Figure 1b As shown, respectively, the DC bus voltage waveform obta...

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Problems solved by technology

[0003] In related technologies, a DC value is obtained by filtering the sampled value of the DC bus voltage, and then an inversion operation is performed based on the DC value. However, since the DC bus voltage actually fluctuates, if a uniform DC value is used for Inverting operation, there will be problems with the voltage output by the inverter, which is manifested as the envelope of the motor phase current will load the ripple on the DC bus voltage

When the frequency of the phase current of the motor is close to the frequency of the AC input power supply, there will be frequency resonance, which will greatly amplify this fluctuation, which we call the phenomenon of DC bus voltage ripple. The precise control of the motor, and in the case of excessive motor load, it is likely to cause the motor to stop out of step

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