Research On Frequency Conversion Circuit Without Electrolytic Capacitor By Power Decoupling

With the popularity of electrification,in order to improve system performance,meet the requirements of capacity and energy saving,three-phase motors with stronger functions are used instead of single-phase motors in small power applications such as home appliances.In order to maintain the stability of system bus voltage,a large capacity electrolytic capacitor is usually connected to the bus of single-phase to three-phase system.The existence of large-capacity electrolytic capacitors limits the service life of the system,and it is also difficult to meet the development trend of system miniaturization.Therefore,it is of great theoretical significance and application prospect to study the single-phase input three-phase output frequency conversion system without electrolytic capacitors.Aiming at the above problems,this paper has studied the structure and working principle of the single-phase input three-phase output frequency conversion system by referring to a large number of related documents.The mathematical relationship between the rectifying part and the inverting part of the system and the bus capacitance is analyzed,which lays a theoretical foundation for the removal of the electrolytic capacitance in the frequency conversion circuit.In this paper,the power decoupling method without electrolytic capacitor is studied,and the principle of absorbing pulsating power and removing electrolytic capacitor is analyzed.On this basis,this paper studies a control method of reducing capacitance which is suitable for single-phase input three-phase output frequency conversion system.Through the control of parallel decoupling circuit,the power ripple of the system is buffered,so as to reduce the bus capacitance.Because the capacitance value of the bus bar is greatly reduced,a thin-film capacitor can be used instead of the electrolytic capacitor to achieve the purpose of extending the life of the system.Then,through mathematical analysis,the decoupling effect of the method studied is theoretically verified.Compared with other methods,the decoupled circuit control strategy of this paper is simple,and each part of the circuit can be controlled separately,which has strong practicability.Finally,based on the theoretical analysis,this paper carries out the relevantsimulation verification,and builds the experimental prototype platform,and carries out the experimental verification.The experimental results verify the correctness and feasibility of the theory.