Direct-current voltage balancing plate for modular active filter

Abstract

The invention relates to a direct-current voltage balancing plate for a modular active filter. The direct-current voltage balancing plate comprises a first voltage balancing resistor, a second voltage balancing resistor, a first signal conversion resistor, a second signal conversion resistor and a comparator, wherein the first voltage balancing resistor and the second voltage balancing resistor have the same resistance and are connected in series; the two ends and the serially-connecting points of the first voltage balancing resistor and the second voltage balancing resistor are respectively connected with the two ends and the midpoint of each serially-connected branch in the active filter; each serially-connected branch is formed by connecting even capacitors in series; the first signal conversion resistor and the second signal conversion resistor are respectively connected at the two ends of the first voltage balancing resistor and an output port of the direct-current voltage balancing plate; the positive end of the comparator is connected with the connecting end of the first voltage balancing resistor and the first signal conversion resistor, and the negative end of the comparator is connected with an external reference voltage; the output end of the comparator is connected with the output port of the direct-current voltage balancing plate; the output port of the direct-current voltage balancing plate is also connected with a control plate. Besides the function of balancing the voltages of the capacitors in the modular active filter, the direct-current voltage balancing plate for the modular active filter also has the functions of direct-current high-voltage signal conversion and over-voltage protection of direct-current voltage.

Description

technical field [0001] The invention relates to a direct current equalizing plate for a modular active filter. Background technique [0002] Active filters are now more and more widely used in the control of power grid harmonics. In order to solve the problems of inconvenient on-site maintenance of traditional cabinet structures, modular active filters have also begun to be developed and applied. However, compared with the cabinet structure, the modular structure has limited internal space, so the design of many cabinet structures cannot be directly extended. [0003] When the active filter is running, the DC voltage is relatively high and a large capacitor is required to support the DC voltage, so the method of connecting multiple electrolytic capacitors in series is basically used. In order to ensure equal voltage between the series capacitors, a resistor is connected across each capacitor. There will be multiple resistors and across the DC voltage, the resistors will be...

AI Technical Summary

Problems solved by technology

The structure of the modular active filter is very compact, and the heating of the resistor may damage its adjacent devices, such as the insulating film between the DC positive and negative copper bars, thereby damaging the device; in addition, the control part of the active filter needs to collect DC voltage For control, the high voltage is not conducive to the simplification of the control board design; in addition, DC overvoltage is a common cause of damage to active filter devices, which will cause critical IGBT (insulated gate bipolar transistor) modules and capacitors The device is damaged or even causes a fire, so the protection requirements for DC overvoltage must be reliable. The current control boards are equipped with DC overvoltage hardware protection, but when the circuit fails and the protection fails, it will directly threaten the safety of the device.

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