Single-phase direct AC-AC variable frequency circuit based on lookup table method and control method thereof

Abstract

The invention discloses a single-phase direct AC-AC variable frequency circuit based on a lookup table method and a control method thereof. The single-phase direct AC-AC variable frequency circuit based on the lookup table method comprise an LC (inductor-capacitor) filter link and rectifier bridges composed of P and N groups of transistors (VP1 to VP4 and VN1 to VN4). A control link is composed ofa sampling device, a microprocessor and a peripheral component and is used for generating a correspondence table of transistor trigger angles and average output voltages and a load's AC signals of expected frequency and amplitude; according to the expected voltage value of each moment, searching a table for the average output voltage having a minium difference absolute value with the expected voltage value; controlling trigger signals of the transistors according to the trigger angles corresponding to the average output voltage, and controlling, in combination with load current, two rectifierbridge groups to alternately operate according to the expected frequencies. The single-phase direct AC-AC variable frequency circuit based on the lookup table method and the control method thereof are suitable for converting sinusoidal or non-sinusoidal input high-frequency alternating current into low-frequency alternating-current output power; the lookup table method and the pulse equivalency principle are utilized, the average output voltage in each high-frequency period reflects a current expected voltage value; the expected output voltage is imparted to the load through a filter circuit.

Description

technical field [0001] The invention belongs to the technical field of power electronics application, and relates to a single-phase direct AC-AC frequency conversion circuit based on a look-up table method and a control method thereof. Background technique [0002] In some remote and remote areas, temporary industrial sites, disaster relief emergency, national defense and military, power supply load shortage and other business sites, it is often necessary to have a mobile, economical and applicable backup power supply. The high-frequency AC power supply has been widely used in the above-mentioned occasions because of its high-frequency working mode, which reduces the requirements for the output filter capacitor and reduces the volume and weight of the equipment. However, both power generation equipment and electrical equipment will have some harmonic interference, so that the high-frequency alternating current generated is not a perfect sinusoidal signal, and there may even ...

AI Technical Summary

Problems solved by technology

This method uses too many comparisons and calculations, which has poor real-time performance and high difficulty in control, resulting in low output voltage THD and easy to cause harmonic pollution. In addition, this traditional single-phase AC-AC frequency conversion circuit uses a three-phase rectifier bridge arm, which uses more thyristor resources

[0006] Regardless of the traditional AC-AC direct conversion or AC-DC-AC indirect frequency conversion, there must be a relatively perfect sinusoidal input signal, but in many occasions, inductive and capacitive equipment will inevitably cause harmonic interference to the sinusoidal signal, making the input high frequency Alternating current has relatively large waveform distortion

If the waveform distortion is too large, the traditional AC-AC direct frequency conversion and AC-DC-AC indirect frequency conversion will not be used

Images