Development Of Test System For H-bridge Unit Of Cascaded SVG

ABSTRACT: With the quality of power supply requirements and the development of power electronic devices, cascaded H-bridge SVG has got a wide range of applications in recent years. The cascaded H-bridge SVG has many advantages,such as low switch frequency and high power output, low cost, low harmonic pollution,and so on.This thesis takes the project of "35kV/15Mvar cascade H-bridge SVG device" in China Power Science Research Institute as the background. In order to meet the needs of production and test, this thesis develops a test system for detcting H-bridge unit, which is the core device of cascaded SVG.The test object is H-bridge unit. First, this thesis makes a detailed study for structure and working principle of H-bridge unit. According to the performance index of H-bridge and test requirements, the overall design of the test system is determinned. After many scheme selections, the final plan is got. The upper computer of the test system is a integration industrial computer called TPC7062K, which is based on MCGS, and the lower one is a circuit board including ARM and CPLD.Divided into the hardware part and software part, this thesis detailed describes the development process of the test system. The design of hardware part contains the minimum system design of STM32, the peripheral circuit design of EPM1270, the design of communication interface circuit, the design of optical transceiver interface circuit, and so on. And the design of software part contains the software design of the upper computer and ARM and CPLD program design in the lower computer. It takes serial communication based on Modbus protocol between the upper and the lower computer, and it takes serial communication between the test system and and the test object.In addition, the thesis also has tests on the test system. In order to check the accuracy and stability of the test system, it needs performance tests. And in order to check the applicability of the test system, it needs t H-bridge unit tests. Through the tests, it is proved that the test system developed in this thesis not only meets the test requirements, but also plays a stable performance.