A PWM rectifier control method and device

Abstract

The invention discloses a PWM rectifier control method and device. The method comprises the following steps: S1, obtaining a preset number of control vector predicted values by prediction; S2, permutating and combining the control vector predicted values to obtain different vector sequences; S3, selecting, from the vector sequences, a vector sequence with least switching times as a control sequence of a PWM rectifier. The method is able to limit the switching frequency of a system under the condition that the prediction period is not changed, and can ensure the dynamic performance of the system, is simple and fast in response, and has a flexible processing system constraint.

Description

technical field [0001] The invention relates to the technical field of PWM rectifier control, in particular to a method and device for controlling a PWM rectifier. Background technique [0002] Control the DC side voltage to maintain a constant DC bus voltage. Its output is used as the AC current (or power) command of the inner loop of the AC current (or power), and the inner loop of the AC current (or power) is used to quickly and timely adjust the voltage of the AC side. Current, suppressing the influence of load disturbance, so that the actual AC current can quickly track the AC current command, and realize unit power factor control. In double-loop control, the voltage outer loop and the current (or power) inner loop must cooperate in speed, and the outer loop is much slower than the inner loop. This type of control mainly includes voltage-oriented vector control (VOC) and direct power control (DPC). [0003] Nowadays, VOC is one of the widely used control strategies in...

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Problems solved by technology

In this scheme, the prediction and optimization mode is the correction of the optimal control, which is convenient for modeling; the rolling optimization strategy is adopted to make up for the uncertainty caused by model mismatch, distortion, interference, etc. in time, which improves the immunity and adaptability However, because there is no fixed switching frequency and the switching frequency is high, it is difficult to obtain engineering applications in high-power PWM rectifiers

[0007] The patent application number is 201610983876.1, and the title is "A Torque Control Strategy for Permanent Magnet Synchronous Motor Based on Flux Vector", which is the background technology document of this application. In order to reduce the switching frequency and reduce the loss, the document calculates and uses another value function to maximize The optimal duty cycle of each alternative voltage vector in one hour is used to realize the torque control strategy based on the flux linkage vector. However, since the switch combination is still updated in each prediction period, the reduction of the switching frequency by this method is very limited.

[0008] The defects in the prior art mainly include: 1. Each calculation outputs an optimal switch combination. When the prediction period is small, the switching frequency will be too high; 2. The method of prolonging the prediction period can reduce the switching frequency. However, when the prediction period is lengthened, it will cause an increase in harmonics, which will affect the control performance of the system

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