| In recent years,instantaneous high-energy high-power pulse loads such as measurement and control radar and electromagnetic ejection have been widely used.However,the frequent fluctuation of the power required by the pulse load will cause the power fluctuation of the power supply system and affect the power quality of the power supply.This paper takes the three-phase PWM rectifier as the research object,analyzes the operating characteristics of the system after introducing the pulse load,and proposes a power fluctuation suppression method on this basis.In order to study the working characteristics of the pulse load,a mathematical model of the pulse load is established,and the influence of the pulse load on the power supply system is studied based on the mathematical model,and the relationship between the energy storage capacitor parameters and the power fluctuation suppression effect is analyzed.Based on the above analysis,the influence mechanism of pulse load on the three-phase PWM rectifier system is studied.At the same time,the effects of pulse duty cycle,duty cycle and peak power changes on the three-phase PWM rectifier bus voltage fluctuation rate and the input side active power peak-to-average ratio are analyzed.The energy storage capacitor is used to realize the power decoupling of the pulse load,and the three-phase PWM rectifier is used to provide the average power of the pulse load,which can effectively suppress the power fluctuation of the input side and improve the power quality of the input side.Based on the control scheme proposed in this paper,in order to achieve power fluctuation suppression,an average power control method with output working condition detection function is designed.The control method includes modules such as pulse load condition detection,pulse load average power calculation,input side instantaneous active power calculation,and output power slope limit.At t he same time,the above model was built using Plecs simulation software to verify the effectiveness of the proposed control method.According to the index requirements of the pulse load,the main circuit parameter design is carried out,which mainly includ es the selection of the power switch tube,the parameter design of the AC side main power inductor,the DC side filter capacitor and the energy storage capacitor.The design method of part of the functional circuit of the three-phase PWM rectifier is given specifically,including the design method of the sampling circuit and the driving circuit.At the same time,the design method of the working condition detection circuit in the energy storage capacitor is given.Based on the proposed control method,the realization of the system software program is explained in detail,including the system flow diagram and the realization of the main functional sub-modules.Use the designed software and hardware platform to carry out engineering environment simulation tests to verify the effectiveness of the proposed control method.In the engineering environment simulation test,steady-state and dynamic performance tests are carried out.At the same time,6 kinds of pulse working conditions with different periods,duty cyc les and peak powers are tested,and the test results meet the design index requirements.It further verifies the feasibility of the control method proposed in this paper to suppress the AC side power fluctuation and improve the AC side power quality. |
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