DC-side Harmoincs Suppression For The Coil Heating Power

Due to the double star rectifier has simple circuit structure,low conduction loss and high energy conversion efficiency,thus it becomes the main circuit topology of coil heating power.As a kind of strongly nonlinear load,the double star rectifier,produces a large number of harmonic current and serious harmonic pollution on power grid.coil heating power usually works in low voltage and high current power supply.In high current application,harmonics impact on power quality are more serious.Therefore,basic on the DC side active harmonic suppression technology and specific characteristics of coil heating power,the AC side current harmonic suppress at DC side is study,mainly on its feasibility,the DC side harmonic suppression mechanism and the active inter-phase reactor is designed and implemented.According to the AC side and DC side current relationship,the function expression of input current and DC side circulatin is established.The type of circulation is analyzed and theoretical support for the DC side suppress AC side current harmonic is provided.First,the input and output characteristics of the conventional double star rectifier is analyzed.The harmonic composition of the input current has been clear.Then,the function relationship of AC side input current and DC side circulation is analyzed,the possibility of suppression input current harmonic at the DC side is available.The expression and the shape parameter of DC circulation are given.The energy characteristic of the DC side of circulation loop also is analyzed.,the analysis results show that when the harmonic energy is extracted from DC side,the input current harmonic is suppressed effectively.Finally,the theoretical analysis is verifies by the simulation results.Considering the shape parameter of circulation at DC side for suppression the input current harmonics,the function of the active inter-phase reactor(Active inter-phase reactor,AIPR)is clear and the specific design of AIPR is given.Considering the voltage across the inter-phase reactor,the circulation extraction circuit should not only work in the unit power factor,and to extract the harmonic energy feedback to load,therefore circulation extraction circuit is selected for the single-phase PWM rectifier topology.The working process and principle of the coil heating system based on AIPR is given.On this basis,the design of the main circuit parameters of the circulation extraction circuit is given,such as the AC input inductance value and the DC side capacitors.Considering the function of the circulation extraction circuit,control and drive circuit has been designed reasonably,so as to guarantee the circulation extraction circuit can accurately extract the circulation,and the input current harmonic is suppressed effectively.Base on the specific design scheme,a coil heating system based on AIPR is developed.In order to verify the harmonic suppression effect of AIPR and the characteristics of the system,the experimental results are analyzed in detail.Through the theoretical analysis and experimental results,it can be seen that the capacity of the AIPR used to suppress the input current harmonics is very small.When the AIPR is applied to the system,the THD of the input current can be reduced to the allowable value while maintaining the low conduction loss of the system,which shows that AIPR technology applied to low-voltage high-current industrial applications has a practical value.