Second Harmonic Current Suppression Method of Two-stage Single-phase Inverter Based on Repetitive Control

Abstract

The invention discloses a method for suppressing the second harmonic current of a two-stage single-phase inverter based on repetitive control. The method can significantly suppress the second harmonic current of the inductor current, thereby effectively suppressing the input second harmonic In this method, the sampling signal of the inductor current of the front-stage direct-to-direct converter is passed through the repetitive controller, and the output of the repetitive controller and the sampling signal of the inductor current are used as the feedback signal of the current regulator, and the output signal of the voltage regulator is the output signal of the current regulator. The reference, the current regulator generates a modulation signal, and sends it to the PWM modulator, and finally obtains the main power tube Q that controls the Buck type direct-to-direct converter through the drive circuit. 1 ~Q n The method has the advantages of suppressing the second harmonic of the inductance current of the two-stage single-phase inverter and its odd harmonics, and the control circuit structure is simple and easy to implement.

Description

technical field [0001] The invention relates to the technical field of control in electric energy conversion devices, in particular to a method for suppressing the second harmonic current of a two-stage single-phase inverter based on repetitive control. Background technique [0002] At present, distributed power generation systems such as new energy, aircraft and electric vehicles are usually compatible with traditional low-voltage DC power supply system specifications, such as 28V, 42V and other DC power supplies. In order to obtain the 115V or 220V AC required by the load, it is usually necessary to adopt a two-stage structure - the front-stage DC-DC converter completes the inverter input and output voltage matching and electrical isolation, and the rear-stage inverter completes the DC-to-AC conversion and supplies the terminal power supply to the load. [0003] In the two-stage single-phase inverter, since the instantaneous output power of the latter stage inverter conta...

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Problems solved by technology

The second harmonic current will not only increase the current stress of the switch tube, but also increase the conduction loss of the switch tube and the loss of magnetic components, and will affect the soft switching of the switch tube, which is not conducive to improving the efficiency of the converter

On the other hand, the double-frequency low-frequency pulsation in the input current will cause interference to the input source, affect the performance of the input source, and have a major impact on the life of new energy sources such as fuel cells. The standard stipulates that it must be controlled at a small value

[0004] Increasing the DC bus capacitance is the easiest way to suppress the pulsating current, but this will increase the volume of the system, which is not conducive to the improvement of the power density of the converter

The method of paralleling the bidirectional converter on the DC bus can achieve the effect of suppressing the pulsating current without increasing the bus capacitance, but this increases the complexity of the system and is not conducive to the improvement of reliability

For the direct-to-direct converter with double-loop control, methods such as adding a band-stop filter to the output of the voltage loop, adding a band-pass filter to the current sampling link, and virtual impedance can effectively suppress the second harmonic ripple of the input inductor current. It will indirectly increase the size of other sub-harmonics, and the suppression effect is limited

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