Research And Making On One 6KV-900KW Cascaded High Voltage Frequency Converter

Since the 1990s,with the people'meaning strengthening of conserving energy and protecting the environment,the use of frequency converter becomes more and more popular.But the energy use factor of our country'motor-driven system is actually extremely low.Especially in the domain of high-voltage electrical motor,the use factor is lower than overseas averge level by 30%.So to promote the use of high-voltage frequency converter is gradually obtained the national value. The cells in series multi-level high voltage frequency converter(CSHVFC) obtain the widespread application in the high-voltage frequency conversion domain because its redundant reliability and perfect output wave shape.The paper has conducted the comprehensive system thorough research to CSHVFC,studied the hardware and software design to make the multichannel real-time SPWM pulse with dislocation phase shifting.The paper include the following contents:(1)The paper researchs the topology of CSHVFC , the basic principle of high-voltage output and velocity modulation with the frequency conversation.The paper also introduces the main part of power unit in CSHVFC. CSHVFC uses many cells in series to form the high-voltage output.Therefore, CSHVFC uses the phase-shifting transform power as input.The phase-shifting method of vice-side winding is analyzed.In order to enhance the reliability,the bypass design of CSHVFC is given out.(2)The hardware circuit design of CSHVFC is introduced. CSHVFC works in high-voltage environment,but its control system works in weak electricity environment.In order to reduce the disturbance to the control system,the optical fiber communications is used between CSHVFC and its control system.The pulse transformer and the light separates are used to carry the control signals to the primary electronic device on the dual isolation.(3) CSHVFC uses many power cells in series to form the high-voltage output,but each unit needs a dislocation phase shifting type SPWM pulse to carry on the control.In order to produce the real-time SPWM pulses,the logical component"Field Programmable Gate Array-FPGA"is used.FPGA is a logical component which can't carry on the computation,so it needs the data from the master control.The connection design between the master control and FPGA is the design key to utilize FPGA reliably.The paper finally produces the experimental wave of a 6KV-900KW CSHVFC.The CSHVFC has achived the anticipated target for its each performance index in the field test.