Research On The Single-phase10kVA Variable-Frequency Power Supply For Measurement

Like ordinary inverter power supplies, variable-frequency variable-voltage powersupply is a device which take use of electrical energy conversion technology to convertelectrical energy of the mains or battery into another kind of power which users need.As the output voltage and frequency can be adjusted according to the needs of the users.Variable frequency power supply can be widely used in various occasions: industrial,military, civilian,etc. Therefore, producing variable frequency power supply with highreliability, good accuracy, good performance has been the goal of the pursuit of thepeople. This goal has become a possibility with the power electronics and a variety ofnew control theory are discovered and emerging. Variable frequency power supply ofhigh performance has broad application prospect. This paper take in-depth researchabout the variable frequency power supply, respectively from the main circuit, drivercircuit, control strategy and DC magnetic bias. The main work is summarized as thefollowing aspects:Combined with an off-campus company’s co-operation project, a digital control of asingle-phase input variable-frequency power supply system is presented based on FPGA,which adopts the FPGA chip EP2C35F672C6from ALTERA. Its capacity is10kVA andthe voltage is adjustable within0~250V, while the frequency is adjustable within20~300Hz.The hardware platform is built. Main circuit and auxiliary circuit are designed.In order to improve the safety and reliability of the system, the signal monitoringsystem and protection circuit of the power supply system are designed. The samplingcircuit, which is constituted by a sensor or a transformer is designed to sample thesystem input parameters, the DC bus and output voltage and current signal of the system.the signals after sampled will be processed by the signal conditioning circuit, and thentransformed to the the control system to form a feedback. Based on the feedback, thecontrol system take its corresponding operation.The transformer is designed and a detailed analysis of the reasons for its cause DCmagnetic bias problem is discussed. This paper summarizes the reasons caused themagnetic bias problem and gives the corresponding measures, and thus improving theability of anti bias magnetic of the power supply.Based on in-depth study on controll strategy of variable frequency power supply,SPWM control strategy is applied into this paper. The double-loop(inductor currentinner loop, the voltage outer loop)PID control strategy is used for controlling system.The simulation results show the feasibility and good dynamic and static performance ofthe strategy and PID algorithm. And show that the strategy improve the accuracy of thesteady state and the performance of the output of variable frequency power supply.