Suppression Method of Circulating Current and Current Oscillation and Parallel Inverter Drive System

Abstract

The invention relates to a circulating current and current oscillation suppression method and a parallel inverter drive system. Suppression three-phase current generated by total output of each inverter driver to a motor after being connected with an entity reactance device is received by using a virtual reactance device, and a compensating three-phase current is generated according to motor impedance and an ideal reactance value generated by the virtual reactance unit and the entity reactance device so that current oscillation of transition three-phase current outputted by a switching device is enabled to be reduced, and the current oscillation suppression effect similar to the effect of enhancing the reactance value of the entity reactance device can be generated. Besides, a corrected three-phase voltage command is generated by using a circulating current suppression device according to the circulating current and / or zero sequence current amount of the parallel inverter drive system so as to suppress circulating current and zero sequence current in the parallel inverter drive system.

Description

technical field [0001] The invention relates to a method for suppressing circulating current and current oscillation, especially a virtual reactance unit generated by using a virtual reactance device to suppress current oscillation together with a physical reactance device, so that it can be used in a circuit with a small volume and low cost. A lower physical reactance device, or a method of suppressing circulating current and current oscillation to improve the current suppression effect of the real reactance device, and a parallel inverter drive system. Background technique [0002] Generally speaking, the motor needs an inverter drive to control the change of the frequency of the rotor magnetic field of the motor and adjust the rotational speed of the motor, so as to drive the operation of the motor. In order to increase the safety of the motor during operation, a parallel inverter drive system has been proposed, which is to connect the outputs of multiple inverter drives ...

AI Technical Summary

Problems solved by technology

However, when the inverter drive operates in a high-power state, it is necessary to use a reactance device with a higher reactance value, and because the reactance device with a higher reactance value has a larger volume and weight, in addition to causing a parallel inverter drive system In addition to the large volume corresponding to the strain, it also increases the cost of the parallel inverter drive system

Although some technologies use LCL filters to replace reactance devices, the complexity of this structure is high, and because the LCL filter requires electrolytic capacitors with a short service life, that is, the electrolytic capacitors in the LCL filter need to be replaced frequently. Therefore, the cost of the LCL filter will be incurred, so the parallel inverter drive system will still have the problem of cost

In addition, when the above three parallel inverter drive systems are in operation, due to a slight error between the independent inverter drives, the current of each inverter drive cannot be completely output to the motor, resulting in the current of each inverter drive reciprocal circulation

Although the above three parallel inverter drive systems all have the function of suppressing the circulating current, the above three parallel inverter drive systems still have the problem of zero-sequence current related to the suppression of the circulating current when suppressing the circulating current, so the suppression effect is still limited

Images