Circulating current control method and device for parallel power converters

Abstract

The invention discloses a circulating current control method for parallel power converters. The method includes the steps of 1, calculating magnitude of circulating current of k moment according to a circulating current value of the k moment; 2, adjusting a phase position of a k moment carrier signal according to a phase shift; 3, calculating magnitude of circulating current of k+g (g> / =1) moment according to a circulating current value of the k+g moment; 4, determining changes in the magnitude of the circulating current before and after phase adjustment; 5, adjusting the phase position of a k+g (g> / =1) moment carrier signal according to the changes in the magnitude of the circulating current. The method has the advantages that circulating current caused by a phase difference among PWM (pulse width modulation) carrier signals of power converters in a parallel power conversion system can be suppressed effectively and reliably, the limitation on the quantity of the parallel power converters in parallel power conversion equipment is avoided, and circulating current suppression is convenient to implement. The invention further discloses a control device employing the circulating current control method for parallel power converters.

Description

technical field [0001] The invention relates to the field of power conversion device control, in particular to a method for controlling the circulation of a parallel power converter device composed of a plurality of power converters. The invention also relates to a control device for a parallel power conversion device. Background technique [0002] The parallel connection technology of power conversion devices is an important technical means to expand the power of power conversion devices, improve reliability, and realize flexible adjustment of power conversion device power. Circulating current is a problem that must be solved for parallel power conversion devices, which makes circulating current control technology the key and core of parallel technology for power conversion devices. Chinese invention patent CN200810166314.3 (application date: 2008.09.19) proposes to control the circulating current by using the sum of the positive and negative bus voltage difference and the...

AI Technical Summary

Problems solved by technology

However, when the number of parallel power converters in the parallel power converter device is too large, the method based on the same clock signal will not be able to cope with the resource limitation of the PWM port of the controller; the bus mode, communication mode, etc. need to add a synchronization line (synchronization line), Communication lines, etc., and when the synchronization line and communication line receive interference, it is easy to cause the phase difference between the carrier signals to become larger, which in turn leads to a large circulation

In addition, even if the phase difference between the carrier signals is eliminated by methods based on the same clock signal, bus method, communication method, etc., the generated PWM switching signal may still be amplified by the driver before being sent to the power module through the driver amplifier of the driver amplifier circuit. Subtle differences in the circuit itself or external interference cause inconsistencies in the PWM switching signal before and after the drive amplification, resulting in a large circulating current in the parallel power converter device

Images