Research On Ripple Current Suppression Technology Of Power Electronic Circuit

In recent years,with the development trend of high-frequency and miniaturization of power electronic circuits,the switching speed is improved and the PCB layout is more compact.High du/dt and di/dt are easily generated by switching action,which is manifested as ripple current,and leads to many problems,such as reducing the circuit transient response,interfering with the operation of electronic equipment,weakening power quality and so on,Therefore,the research on ripple current suppression technology has become a hot spot.At present,the ripple current suppression technology is mainly divided into active and passive.Among them,active technology has attracted much attention because of its small size and the ability to dynamically adjust the suppression ability.However,due to the narrow passband,signal phase shift and low stability of active devices,the suppression ability is limited,so only the ripple current with small amplitude can be suppressed;although passive technology has low cost and simple design,its suppression ability is easily restricted by the coupling coefficient of magnetic devices,and the loss is large.To solve these problems,this paper proposes novel active and passive technologies for the ripple current at the input side of traditional Buck,Boost and Flyback converters,and makes a detailed research and discussion.Firstly,guided by the intermittent trapezoidal ripple current at the input side of Buck converter,this paper proposes an active ripple current suppression technology of controllable power transistor filter,which mainly uses the power transistor and capacitor to form an active ripple suppression circuit,and synchronously controls the switch and power transistor through the proposed feedback double loop control mode,While ensuring the normal operation of the converter,the power transistor is controlled into a constant current source to suppress the ripple current.Then the working principle and control scheme are analyzed in this paper,gives the detailed design method of each part of the circuit,carries out experimental verification,and makes a simple comparison with LC filtering technology.The experimental results show that the technology has the characteristics of easy integration and high stability.Compared with LC filtering technology,the efficiency is slightly lower,but it has absolute advantages in space volume.In addition,different from the active technology based on Reverse Elimination,the active technology mainly uses the constant current characteristics of the power transistor to realize the suppression function,and there are no problems such as narrow frequency band and compensation signal phase shift.Moreover,the reasonable selection of the power transistor can make it suitable for the suppression of large ripple current,which greatly widens the application range.Secondly,based on the continuous triangular ripple current at the input side of Boost converter,a current compensated passive ripple current suppression technology is proposed in this paper,which mainly uses the transformer and DC isolation capacitor to form a passive ripple compensation circuit.Under the designed ripple suppression condition,it can produce the opposite ripple compensation current to offset the triangular ripple current,The interference on the input side is greatly reduced.Then its working principle is analyzed,the system gain and ripple current suppression conditions are obtained by time domain analysis method,and compared with the boost inductance of boost converter under the same ripple coefficient,so as to illustrate the feasibility of passive ripple compensation circuit from two aspects of volume and loss.Finally,the experimental results show that it not only suppresses the ripple on the input side,but also greatly reduces the inductance volume of the main circuit.Because there is no DC through,it has the characteristics of small loss,simple design and high stability.In addition,the boost PFC converter using this technology is simulated.All the results show that the suppression ability of current compensated passive ripple current suppression technology is not restricted by the coupling coefficient of transformer,and does not affect the working state and gain of Boost converter,which solves the common problems of general passive technology.Finally,taking the intermittent trapezoidal ripple current on the input side of the traditional Flyback converter as the problem guide,based on the improvement of the passive ripple compensation circuit,the proposed active and passive technologies are compared in detail from the aspects of suppression ability,power loss,power density,cost and applicability.The experimental results show that the active ripple current suppression technology of controllable power transistor has absolute advantages in power density and application range;current compensated passive ripple current suppression technology has absolute advantages in power loss and cost,and has comparative advantages in suppression ability.This provides an important reference for the suppression scheme design of ripple current in other power electronic circuits.