Over-voltage protection method for DC bus voltage of wind power current transformer and circuit adopting same

Abstract

The invention discloses an over-voltage protection method for the DC bus voltage of a wind power current transformer and a circuit adopting the same. The method comprises the steps as follows: a square wave signal with a certain amplitude value, a certain frequency and a certain positive duty cycle is generated correspondingly according to the actually needed over-voltage protection value of a DC bus voltage by adopting the software table checking method of a DSP (Digital Signal Processor) chip; the square wave signal is compared with a normal value signal to output a square wave signal with a certain amplitude value, the identical frequency and the identical positive duty cycle, and the circuit completing the first time comparison output is a primary comparison circuit; the square wave signal receives special circuit treatment to be changed into a normal value signal reaching the pre-determinate over-voltage protection value of the DC bus voltage, the normal value signal and the conversion value of the actually detected DC bus voltage are compared to send an output signal to the DSP chip, and the circuit completing the second time comparison output is a secondary comparison circuit; and the DSP chip decides whether overvoltage exits in the DC bus voltage of the wind power current transformer.

Description

technical field [0001] The invention belongs to an overvoltage protection method and circuit, in particular to a wind power converter DC bus voltage overvoltage protection method and circuit. Background technique [0002] When the intermediate DC bus voltage exceeds a certain limit, the wind power converter will cause abnormal operation of the converter and is prone to failure. Therefore, the general converter will be used with the DC bus voltage overvoltage protection circuit. At present, in wind power converters, the DC bus voltage is mostly divided by resistors to obtain the upper limit value of the protected value, and the comparator outputs a signal representing the overvoltage of the DC bus voltage to the DSP. The high voltage limit value of the overvoltage protection circuit using this method can only be changed by changing the hardware device, and the resistance value of the hardware device resistance is limited by the size of the circuit board pad, so basically a ce...

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Problems solved by technology

The high voltage limit value of the overvoltage protection circuit using this method can only be changed by changing the hardware device, and the resistance value of the hardware device resistance is limited by the size of the circuit board pad, so basically a certain converter The DC bus overvoltage protection hardware determines the high limit value of the DC bus voltage, which makes the application of the overvoltage protection circuit very inflexible, and it is also very difficult to change the overvoltage protection value

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