| Hybrid active third-harmonic injection matrix converter(H3IMC)is a new kind of matrix converter(MC),integrated with active front-end converter and voltage source converter.Compared with traditional MC,H3 IMC not only inherits the characteristic of no DC bus energy storage element,but also enjoys the advantages of input and output decoupling,controllable passive power,less high frequency harmonic in the input side,and so on.Applying H3 IMC in AC-AC dual power flow condition can save the large electrolytic capacitor for energy storage so as to improve the power density of the system.The advantages of H3 IMC is brought by hybrid active third-harmonic injection converter(H3C),and is realized by valid control of third-harmonic current tracking.In addition,limited by the modulation strategy,the voltage transfer ratio of H3 IMC in forward mode is below 0.866.Thanks to the feature of bidirectional power flow,operating H3 IMC in reverse mode can output wider range voltage,whose magnitude can be 1/0.866 times higher than input one at least.For reliable boost operation,coordinated control of input and output sides is necessary.This paper mainly focuses on the forward and reverse operation mode of H3 IMC.Theoretical analysis,simulation study and experiment validation are used for the research on the third-harmonic current tracking and constant voltage control for reverse H3 IMC.Directly controllable third-harmonic current is the base of inproving the performace of AC side of H3 C.After introducing the topology of H3 IMC and the principle of injecting third-harmonic current,this paper points out the reason of cannot effectively making use of the traditional current tracking method in this topology,and puts forward three harmonic current tracking methods,in which the voltage information of AC side of H3 C is taken into consideration,so as to lower complexity of design of current regulator brought by the difference of inductance voltage,enhance the current control performace in different input conditions.For the proposed closed-loop harmonic control method,the types and parameters of current regulators are designed in the low frequency and middle frequency operation conditions respectively.Guaranteeing stable and controllable load voltage is the primary goal of the control for reverse H3 IMC,besides,improving the AC wave performace of input current is the second goal.Aiming to study the operation principle of reverse H3 IMC system,the mathematical mode is deduced.Based on that,control strategies for reverse operation are proposed for the working condition of resistive load and grid connected respectively.To solve the problem of losing control of load voltage,which is proved possibly occurence at the output side of reverse traditional MC in light load condition,third-harmonic current is injected into the output side,so as to provide the passive power absorbed by the output filter.In this way,the problem of losing control of load voltage is solved from the source.For the control strategy of the working condition of resistive load,which includes outer-loop of voltage and inner-loop of input current,the design of PI regulator of the outer-loop is studied,and the value ranges of PI parameters are analyzed and limited.In the end,models of forward and reverse H3 IMC system are built in the Matlab/Simulink environment,and an experiment prototype of H3 IMC based on digital signal processor and complex programable logic device is designed and realized.The feasibility and validity of proposed control strategies are verified by the simulations and experiments,and experiment condition is provided for further research. |
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