H bridge cascade active electric filter DC side capacitance-voltage equalizing controlling maethod

Abstract

This invention relates to a method for controlling capacity and voltage at the DC side uniformly of bridge-H cascade active power filter, which first of all takes the harmonic current, passive current needed to be compensated by the power net and load system as the compensation current required by the filter, takes the sum of the expected compensation current and fundamental wave positive sequence active current absorbed from the net as the APF reference current to get the APF inverter desired output voltage via a current following controller to drive the APF output current to follow the reference current, computes the micro-tune volume of the output voltage of the cascade unit, carries out micro-micro adjustment to the expected output voltage by the balance controller based on the cascade unit capacitance and voltage deviation and the APF output current to adjust the charge and discharge time of the unit floating capacitance to further realize the balance control of the floated capacitance and voltage takes the adjusted expected output voltage as the reference one of said unit to be modulated in pulse width to get trigger signals of the cascaded bridge-H power device to drive the primary circuit power device.

Description

technical field [0001] The invention relates to an H-bridge cascaded active power filter DC side capacitor voltage equalization control method. Background technique [0002] With the development of power electronics technology, various nonlinear power electronic devices have been widely used in power systems, industries (especially metallurgy, steel, chemical industry, etc.), transportation, building automation and households, and their device capacity is increasing The large and diversified control methods make the voltage and current waveform distortion in the power grid more and more serious, and the harmonic pollution in the power grid is becoming more and more serious. In order to overcome the shortcomings of passive power filter (PPF), an important trend of harmonic suppression devices is to use active power filter (APF) to meet the harmonic standards IEEE519-1992, GB / T14549-93 "Power Quality Public Grid Harmonics" requirements. Compared with PPF, APF has the follow...

AI Technical Summary

Problems solved by technology

[0012] Chinese patent 200310115393.2 and Chinese patent 03142679.4 both balance and control the DC side capacitor voltage of H-bridge cascaded multilevel inverters, both of which are controlled by an additional external The equipment enables the active power exchange between the H-bridge inverters to realize the balanced control of the capacitor voltage. This type of method requires additional equipment and its control, which increases investment and maintenance costs.

For APF, its compensation current is a harmonic current, which requires a high switching frequency, a large change in the pulse width of each H-bridge, and requires rapid capacitor voltage balance. The need for harmonic governance

Images