Overvoltage Protection And Real-time Detection Of The Moderate-voltage Converter

With the rapid development of the industry in recent years, four-quadrant converter has been more widely used in our industry. Particularly in the power of mining production, it has a pivotal role. In addition to reducing power pollution, the four-quadrant converters’ another important role is to save energy, which is very important at this stage of our historic task. But over-voltage phenomenon makes the working environment is not stable and may even damage the inverter equipment to expand accident losses, which causes a lot of energy waste. Current research on over-voltage has already caused widespread concern in the field of industry. Based on the requirements of the subject, this paper regards 1140V four-quadrant converter as the research object, and conducts in-depth understanding and analysis of their work during an overvoltage condition. And then find a solution based on the analysis and implement it.Firstly, conducting a long-term research on work environment of 1140V four-quadrant converter, this paper analyses the causes of a variety of over-voltage phenomenon. According to the characteristics of different overvoltage it classifies and compares them in order to achieve the protection scheme.Secondly, selecting ZnO varistors as one of the main components of the scheme because their characteristics and parameters after the detailed understanding. According to the requirements of the subject, this paper selects the appropriate parameters, designs the circuit and tests boards. Then verify the feasibility of the protection scheme also find the lack of existing programs. According to the inadequacy, continue to find ways to make up until the achieve functions of circuit protection.Thirdly, using isolation and noise immunity techniques, this thesis designs and constructs a low cost measurement system to safely and accurately measure over-voltage signal in harsh environments. The difficulty of accurately measuring high voltage pulses continues to pose an issue. Measuring high voltage systems can cause damage to the system, the measurement system, and the user. Implementing isolation from the high voltage system protects the measurement and user. Commercial off the shelf pulse measurement systems such as oscilloscopes cost thousands of dollars. Cheaper but simpler designs fail to provide isolation for safety. The measurement system in this thesis addresses all of these issues, allowing people to measure and characterize some features of the over-voltage signals. Technologies used in this measurement network include optocouplers and transimpedance amplifiers. The development process describes design, simulations, characterizations, construction, testing, and troubleshooting. Simulations show expected operations of components and characterizations assist in determining performance parameters of the system. Testing involves performing a low voltage test and a high voltage test and identifying limitations of the design.Finally, this thesis suggests future work to improve performance and lower cost of the measurement system.