Device and method for detecting direct-current voltage of power unit element

Abstract

The invention provides a device and a method for detecting the direct-current voltage of a power unit element. A voltage amplitude value is converted into a square-wave signal through six steps of resistance voltage division, voltage amplitude limiting, voltage frequency conversion, optical fiber transmission, burr filtering and pulse counting; and the purpose of detecting the direct-current voltage of a direct-current supported capacitor inside the power unit element is achieved by calculating the number N of high frequency pulses between high levels of two adjacent square-wave signals. As the technical scheme provided by the invention needs no Hall sensors, the price of the device is reduced greatly; and meanwhile the data transmission of long numbers is avoided, the software and hardware design is simplified, and the accuracy in direct-current voltage detection is increased.

Description

technical field [0001] The invention relates to a device and a method for detecting DC voltage of power units of a chained SVG and a chained APF. Background technique [0002] The main circuit of the chain-type SVG and chain-type APF devices is formed by cascading several identical power units. In order to meet the needs of reliable and stable operation of the devices, the main controller of the complete set of devices must provide two DC support capacitors for each power unit. The DC voltage at the terminal is detected in real time. The detection scheme of traditional technology is generally divided into two steps: [0003] The first step is to install the Hall sensor to directly measure the DC voltage, convert the DC voltage from a large signal to a small signal, use a dedicated AD sampling chip or a processor integrated with the AD sampling function to calculate the small signal, and discretize the analog signal into digital Signal; [0004] In the second step, the dig...

AI Technical Summary

Problems solved by technology

[0006] 1. The price of the Hall sensor is very high, and corresponding auxiliary circuits need to be configured, which is not conducive to improving the price competitiveness of the device;

[0007] 2. The power unit body is a strong electromagnetic interference environment, and analog or digital circuits are susceptible to interference. The DC voltage is discretized in the power unit body, and the converted digital signal is prone to errors;

[0008] 3. The contradiction between sampling accuracy and communication reliability is difficult to coordinate. In order to ensure voltage sampling accuracy, the more digits of digital signals representing DC voltage, the better. In order to reduce the communication bit error rate, the fewer digits of digital signals, the better

[0009] 4. Multi-digit digital signal transmission necessarily includes the process of information encoding and information decoding. This process needs to solve many problems such as communication clock synchronization, information verification and error correction, which consumes chip resources and increases implementation difficulty

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