Alternating-current high-voltage detection device and method for medium-high-voltage soft starter

Abstract

The invention discloses an alternating-current high-voltage detection device and method for a medium-high-voltage soft starter. An B phase of a three-phase input alternating-current voltage serves as a reference ground through a voltage sampling module, voltage division of an A phase of the three-phase input alternating-current voltage is performed through a high-voltage sampling resistor, and the divided voltage is input into a single-phase isolation transformer; a low-voltage alternating-current signal is output through isolation and subjected to shaping and filtering processing, and a direct-current voltage signal is sent to the shaping module for shaping and filtering processing and then is transmitted to the signal processing module as a power supply voltage; the voltage signal transmitted by the shaping module is converted into two paths of direct current components by using the signal processing module, and the components are superposed with the other two paths of alternating current voltage signals to obtain a PWM wave with a certain pulse width; and finally, the wave is sent to a post-stage circuit by using the sending end of the signal isolation output module, and the post-stage circuit is used for modulating and demodulating the PWM wave so that the voltage detection of the medium-high voltage soft starter can be realized. The device and the method are higher in safety, high in detection result precision and high in anti-interference capability.

Description

Technical field[0001]The present invention relates to the field of high pressure detection, and more particularly to an alternating current high voltage detecting apparatus and method for medium high pressure soft starters.Background technique[0002]The soft starter is a motor control device, which collects electrical soft start, soft parking, light load energy saving and a variety of protection functions.[0003]The general medium-high-voltage motor soft starter is sampled by a voltage transformer, in a 10kV neutral point inactive system, a ferromagnetic resonance is generated when the nonlinear excitation inductance of the voltage transformer has a ferromagnetic resonance when the line voltage is fluctuating in the line voltage. , The voltage transformer is raised, the voltage transformer magnetic core tends to saturate, the primary coil current increases sharply, and finally, the voltage transformer is overheated and even an explosion accident, so the use of voltage transformer has ...

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Problems solved by technology

Although the voltage transformer using the principle of voltage division is small in size, light in weight, simple in structure, good in linearity, has no resonance, overcomes the shortcomings of iron core saturation, has no load sharing, allows short circuit and open circuit, and has high reliability, but this The detected voltages are as follows: 1. The primary input and secondary output are not isolated, which has great potential safety hazards; 2. The output voltage signal is weak, easily affected by external interference, and the accuracy of the detection results is low

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