Key Research Areas

Compact converters enabling high power density

Compact converters enabling high power density
© Fraunhofer IZM

Due to the low switching losses when using the novel wide band-gap semiconductor generation made from gallium nitride and silicon carbide, respectively, it is possible to increase the switching frequency of power electronic systems significantly. As a consequence, the size of passive components, especially of the bulky ripple inductors, can be reduced, for the reason that less energy needs to be buffered in the system. The focus of the ECPE lighthouse project "Industrial Demonstrator on System Level" is on an additional power density increase by means of innovations in filter topology and semiconductor control.

The control system gathers all measured values simultaneously and regulates the duty cycles of all six half bridges. Both gate signals inside a half bridge are magnetically coupled. As a result, zero dead time switching between top and bottom semiconductor are realized and the switching losses can be further reduced. Due to the very high temporal accuracy of the control signals of less than 500ps the required additional gate charge can be adjusted precisely and oscillations with the gate source capacitance can be avoided. The operation parameters can be transmitted using various interfaces (USB, CAN-Bus and Ethernet) or directly adjusted on the control panel. According to the electrical load conditions the control system supports the application of different operation modes (DCM, CCM, flat top modulation) during one mains period and rotary field period, respectively. In this way, die voltage-time-area of the PFC and motor inductors and thus their size can be further reduced. The size reduction of the CM filter is achieved by shifting the CM voltage into the DC link.

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The ambition of the SpeedDrive project is to develop a high-speed drive that far exceeds what was thought possible with the current state of the technology.