Method and circuit for controlling changing cyclic width lag cyclic current of inventer

Abstract

This invention discloses a controlling method to inverters of width sluggish loop current by changing the loop width and a circuit, in which, the method includes: 1, computing loop width to get a signal of the width of a sluggish loop, 2, sending said signal to a comparison segment of a changed loop width and the sluggish loop, the other input volume of which is the current error signal of the inverter, the comparison segment carries logic operation to get a pulse width modulation waveform to drive the operation of the master circuit switch of the inverter, its circuit is a loop width adjusting circuit and a changed loop width and sluggish loop comparator, which maintains the character of the traditional fixed loop width sluggish loop current control and realizes the constant switch frequency of the inverter controlled by the sluggish loop current.

Description

1. Technical field [0001] The invention relates to an inverter control method, in particular to a hysteresis current control method with variable loop width and a corresponding hardware circuit for realizing the method. 2. Background technology [0002] The current control two-state modulation system uses the actual current signal of the inverter to compare with the current given signal. If the actual current exceeds a certain range of the given value, it controls the increase or decrease of the current by changing the switch state of the inverter to achieve the actual Fast tracking of current to current reference. The current-controlled two-state system also has built-in current-limit protection capability. Usually the inverter adopts double-loop control. Due to the high stability of the current inner loop, the voltage outer loop can achieve high gain, the system output voltage accuracy is high, and the dynamic performance is improved. The current inner loop is equivalent...

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Problems solved by technology

However, the hysteresis current control also has the disadvantage that the switching frequency is not fixed.

People have done a lot of research work to overcome this shortcoming: use phase-locked loop technology to compare the switching signal with a square wave signal with a fixed frequency, get the phase difference, and then get the expected hysteresis comparator ring width through the proportional integral link ;In the control loop, a feed-forward compensation link is added to correct the current error; after three-phase decoupling, the optimized voltage vector is selected to adjust the hysteresis width, and the constant frequency of the hysteresis current control is realized in the occasions such as motor speed regulation and active filter , but this method cannot be applied to single-phase

The above methods need to add control links and additional parameter design, the system design is difficult and the control is complicated; at the same time, some variable parameters of the system need to be estimated; since only the best approximate space vector is selected to participate in the control, the switching frequency still fluctuates, Can only achieve approximate constant frequency

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