Soft-Switching Power Inverter Limits Voltage Edge Rate

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2017-WASY-67795
Virtually all variable-speed motor drive systems, such as those used in hybrid or electric vehicles, and grid-connected renewable generators, i.e., solar and wind, use transistor-based power inverters. Over the past several decades, silicon (Si) transistors, such as metal-oxide-semiconductor field-effect transistors (MOSFETs) and insulated-gate bipolar transistors (IGBTs), have become faster to enable high frequency switching and reduce switching losses. Recently introduced wide-bandgap (WBG) transistors are even faster than Si transistors by one or two orders of magnitude and considered as the next-generation transistor. However, fast transistors generate high voltage edge rates (dv/dt) and can result in serious side effects. Common methods of limiting the dv/dt include increasing external gate resistance or capacitance and/or adding a dv/dt filter at the output of the inverter. These methods are effective, but introduce extra loss, size, and weight to the system. Another technology called soft switching can control the dv/dt at the switch level without generating significant extra losses. There is potential to limit the dv/dt in fast transistors using soft switching with less total loss, size, and weight. However, the available soft-switching circuits were originally developed to reduce switching losses, so they have some drawbacks in terms of limiting the dv/dt.

Researchers at Purdue University have developed a new soft-switching power inverter to effectively limit and control the inverter output dv/dt. This technology augments an inverter with auxiliary circuits. The auxiliary circuits are only active during voltage transitions, so the current ratings of the components are low, which result in smaller and lighter components. This technology not only reduces size/weight of the system compared to conventional technologies, but also generates little extra loss due to soft switching in all switches. It also eliminates the drawbacks in the available soft-switching inverters. The benefits of this technology include effective control of the dv/dt in all conditions, reliable soft switching, more efficient circuits, and smaller size/weight. This technology will benefit manufacturers who want to take advantage of next generation transistors in various applications, e.g., variable-speed motor drives for hybrid/electric vehicles and solar panel to grid integration.

Advantages:
-Limit and control inverter voltage edge rates
-High efficiency
-Small and light components
-High power density
-Integrates into existing inverters

Potential Applications:
-Transportation electrification manufacturers, e.g., hybrid/electric vehicles, off-road vehicles, trains, ships, and aircraft
-Renewable energy integration, e.g., solar panel integration and micro-grid optimization
Jun 8, 2018
Provisional-Patent
United States
(None)
(None)

Jun 8, 2017
Provisional-Patent
United States
(None)
(None)
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