Matrix converter: Improvement on the start-up and the switching behavior

The matrix converter (MC) presents a promising topology that needs to overcome certain barriers (protection systems, durability, the development of converters for real applications, etc.) in order to gain a foothold in the market. Taking into consideration that the great majority of efforts are being oriented towards control algorithms and modulation, this article focuses on MC hardware. In order to improve the switching speed of the MC and thus obtain signals with less harmonic distortion, several different IGBT excitation circuits are being studied. Below, the appropriate topology is selected for the MC and a configuration is presented which reduces the excursion range of the drivers and optimizes the switching speed of the IGBTs. Inadequate driver control can lead to the destruction of the MC due to its low ride-through capability. Moreover, this converter is specially sensitive during start-up, as at that moment there are high overcurrents and overvoltages. With the aim of finding a solution for starting-up the MC, a circuit is presented (separate from the control software) which ensures a correct sequencing of supplies, thus avoiding a short-circuit between input phases. Moreover, it detects overcurrent, connection/disconnection, and converter supply faults. Faults cause the circuit to protect the MC by switching off all the IGBT drivers without latency. All this operability is guaranteed even when the supply falls below the threshold specified by the manufacturers for the correct operation of the circuits. All these features are demonstrated with experimental results. For all these reasons, it can be said that the techniques proposed in this article substantially improve the MC start-up cycle, representing a step forward towards the development of reliable matrix converters for real applications.