Research On Constant-current Source Of Power-frequency Rectification Based On Pwm Control

High-Voltage Electrostatic Precipitator(HVESP)becomes an effective means of dust. As a key part in the electrostatic precipitator system, power supply of ESP directly affects the efficiency of dust removal. Removal of existing devices commonly used with the thyristor-controlled AC voltage regulation, thus that reducte greatly the dynamic response of the system. In addition, when flashover occurs, the system will inevitably aggravate the flashover, and the system has the impact of a large current.At the same time, the use of phased-exchange regulator output voltage means there is bound to cause a lot of volatility. The peak voltage can only work in the vicinity of flashover voltage, the voltage fluctuations in the dust plate to reduce the average voltage, so it is very difficult to improve collection efficiency. The use of high-frequency resonant power supply solved the problem of the slow dynamic response in thyristor-controlled AC voltage regulation.But if the use of high-frequency resonance technology, it is eliminated to the existing precipitator power supply, excessively large investment.In order to solve the electricity problems of phased manner and take into account the costs of investments in technology, the using of current source means to maintain the value of output current in the vicinity of flashover, and using the whole IGBT type devices instead of the thyristor converter, to retain the original step-up transformer, reducing the cost of technology investment at the time.From the above idea, this dissertation is focused on PWM—Control and rectifier combining technology. Through analysis and comparison of the full-bridge PWM converter three modulation, and considering integrated requirements of output current waveform, switching losses and areas such as security and reliability, we can selecte the appropriate modulation mode in the work.In the dissertation, author established the small-signal model of the system.Taking into account the impact of the input bus voltage, author use in controlling the bus voltage equivalence principle- in the control system by adding the bottom part of bus voltage, while the use of the output voltage disturbance compensation to reduce negative impact on the system of the output voltage. Finally, under the simulation environment of MATLAB, builting system simulation model to observe the simulation waveform under variable parameters of load and bus voltage.And verifing the anti-interference ability of the system.Finally, based on the pre-theoretical analysis, a constant current source prototype is constructed. Experimental results demonstrate that system has fast dynamic response, high stable precision, non-overshoot, which can be very good to meet the design Requirements.