Secondary harmonic current suppression system and method based on pulsating power feedback

Abstract

The invention belongs to a control technology in an electric energy conversion device, and discloses a second harmonic current suppression system and method based on pulsating power feedback. According to the method, an inductive current sampling signal and an output voltage sampling signal of a preceding-stage DC-DC converter pass through a multiplier, the output of the multiplier passes through a band-pass filter, the output of the band-pass filter and the inductive current sampling signal serve as a feedback signal of a current regulator together, and an output signal of a voltage regulator serves as a reference of the current regulator. And the current regulator generates a modulation signal and sends the modulation signal to the PWM modulator, and finally a driving signal for controlling main power tubes Q1-Qn of the Buck-type DC-DC converter to work is obtained through the driving circuit. The method has the advantages that the input second harmonic of the two-stage single-phase inverter can be suppressed, and the control circuit is simple in structure, convenient to implement and the like.

Description

technical field [0001] The invention belongs to the control technology in electric energy conversion devices, and relates to a second harmonic current suppression method based on pulsating power feedback. 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 contains pulsating power of twice the frequency of the...

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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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