LCC-SPRC High Voltage, High Frequency And High Power ESP Power Supply-theory Analysis And Power Parameters Design

New technologies of the ESP power supply can significantly improve the dust removal efficiency, and play an increasingly important role in environmental protection. With the energy saving policy and the increasing strict of air pollution emission standards it has now became an important research area. Although the high-voltage, high-frequency and high-power ESP power supplies products of domestic and foreign enterprises gradually enter the market, more and more widely applied, the common problem research is lack, not involving the integration design of resonant converter and high voltage transformer.The high voltage, high frequency and high power ESP power supply is belong to special power supply. It involves a variety of subject content, with some difficulties in study. Based on the basic problem and specificity, advantages of the discontinuous current mode series-parallel resonant converter (DCM LCC-SPRC) in the high-voltage applications are discussed, and relatively systematic study in DCM LCC-SPRC mathematical description and design is carried out.Firstly, more comprehensive mathematic description of DCM LCC-SPRC is given. DCM LCC-SPRC design is based on the mathematical description of the circuit. The most commonly used method, such as simulation and numerical calculation need large computation; the intrinsic relationship between the circuit parameters is uncertainty. Therefore, it is difficult to be used in optimizing the design. Normalized analytic expressions in the simple form are derived in the second chapter, reflecting DCM LCC-SPRC circuit characteristics and containing only two parameters, the equivalent voltage gain and the ratio of the parallel resonant capacitor to the series resonant capacitor. On this basis, more comprehensive mathematic description of DCM LCC-SPRC is given, and a great deal of experimental data verifies its correctness. The research reveals the intrinsic relationship between the circuit parameters for DCM LCC-SPRC; establish the foundation for further research and design.Secondly, integration design method of DCM LCC-SPRC and high voltage, high frequency and high power transformer is proposed.A very important feature of the discussed DCM LCC-SPRC is the high voltage transformer parasitic parameters are used as resonant components. Therefore, DCM LCC-SPRC and transformers are a whole part. The existing literature tend to neglect the intrinsic relationship between them, it is difficult to achieve the overall optimal design. The integration design method of DCM LCC-SPRC and the high voltage transformer is proposed in the third chapter. By reference value transformation and parasitic parameters referred to the high voltage side, the coupling problem of the transformer turns ratio and the parasitic parameters on integration design issues are solved, so that integrated design method can be implemented. The third chapter further gives simple and optimization control under the integrated design, respectively. Examples, including the design steps, simulation, experimental results and comparison of two control schemes are given. Among them, the simple control strategy is simple; optimal control has a higher current output capability, higher frequency and lower current stress and overall excellent performance. Based on the integration design, the transformer parasitic parameters on the circuit characteristics is discussed, provides a theoretical guidance for the transformer design.The capacity expansion study of the DCM LCC-SPRC system is studied in Chapter five. Using the transformer structure of low voltage side parallel, high voltage side series can effectively increase the output voltage; Using the transformer structure of low voltage side parallel, high voltage side parallel can effectively increase the output current. By using the two different methods,95kV high voltage and 1.2A high current output are achieved, respectively.The research results of the integration design method of DCM LCC-SPRC and high voltage transformer has a good value in application; system expansion study establishes the foundation for the ESP power supply in higher output voltage and current application.Thirdly, a complete design example of high voltage, high frequency and high power transformer is given.As a key component of the special power supply, design of the high voltage transformer covers many disciplines knowledge, not only has theoretical depth, but also directly associated with applications. The design method is different from the conventional transformer. The existing literature is lack of detailed design report on the 72kV/1.0A/(>10kHz) output level. Based on the specialty, the design guidelines are proposed, in the process of discussing the related issues, the construction of the high voltage transformer is completed. Theoretical calculation and experimental precision extraction of the transformer parasitic parameters are given, respectively. By comparison of the two ways, the theoretical value has good application value.Research results enrich the design method of the high-voltage, high frequency and high power transformer, while providing guarantee for stable and reliable operation of the ESP power supplies.Finally, large-signal model of DCM LCC-SPRC is established. Determined by the operation characteristics, electrostatic precipitator generates flashover frequently and then the ESP power supply restart. In order to accurately analyze characteristics of the circuits, the circuit model is needed. The commonly modeling method used in resonant converter is based on the general average method and the fundamental component method, which is difficult to be directly applied to DCM LCC-SPRC, in which the resonant current waveform is severely deviate sine waveform and has discontinuous process.Therefore, the differential relationship between the control variable and the output state variable is established in Chapter five, eliminating the coupling with the resonant state variable, Also the relationship between the resonant state variable and the output state variable is established, containing only one resonant state variable and eliminating the coupling with the control state variable. The established DCM LCC-SPRC large-signal model is simply. It is found by simulation that the large signal model has very good description of the circuit start transient process, and has the advantages of fast simulation speed, avoiding the convergence of the circuit.The dissertation has a relatively systematic study of the DCM LCC-SPRC high voltage, high frequency and high-power ESP power supply. The results will not only enrich the high frequency, high power high voltage ESP power supply, but also establish a good foundation for application of the LCC-SPRC power supply.