Abstract
Three-phase isolated matrix converters enable bidirectional power conversion and galvanic isolation, and they are suitable for widespread applications in industry. However, excessive DC-link current ripple not only increases the inductor loss and switching loss but also causes more electromagnetic interference and grid current distortion. Traditionally, increasing DC-link inductance or switching frequency can reduce the current ripple to a certain extent, but it is not cost-effective due to the bulky size of the inductor and higher switching losses. To address the above issue, optimizing the modulation control strategy is more attractive. This paper proposes a new SVPWM strategy to reduce the current ripple. First, the inherent limitation of the conventional modulation scheme is revealed. Then, the new optimal modulation scheme is proposed for the isolated matrix converters to reduce the current ripple without increasing the DC-link inductor or switching frequency. Moreover, the power density of the system is effectively increased. Finally, simulation in a MATLAB environment and a laboratory prototype of the isolated matrix converter have been built to verify the effectiveness of the proposed strategy.
Highlights
With the development of power electronic technology, the requirements for power electronic conversion circuits are constantly increasing
Power converters are widely used in the applications of electric vehicle charging [1], photovoltaic systems [2,3], HVDC systems, and flexible ac transmission systems (FACTS) [4]
From (1), the DC-link current ripple ∆i can be optimized depending on the bridge output voltage Udc, which is determined by the switching states, as shown in Table 2; that is, the DC-link current ripple would be high if Udc steps from the highest to lowest one depending on the vector sequence
Summary
With the development of power electronic technology, the requirements for power electronic conversion circuits are constantly increasing. To deal with the problems caused by the DC-link current ripple, a method by setting the zero vector in a smart way is proposed for a three-phase converter in [16]. Though this method can reduce the current ripple, it suffers high switching losses due to the increasing switching actions. An optimized modulation control strategy for the three-phase isolated matrix converters is proposed to effectively reduce the DC-link current ripple.
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