Planar transformers miniaturize DC-DC converters for IGBT gate drives

November 08, 2016 // By Nick Flaherty
Murata has launched three series of 6W high isolation DC-DC converters to provide all gate drive power for half, full, and three-phase bridge circuits, saving space and cost.

The MGJ6HB, MGJ6FB, and MGJ63P series DC-DC converters are for simultaneously powering “high-side” and “low-side” gate drive circuits for IGBTs, and silicon/silicon carbide MOSFETs in bridge circuits. The devices feature respectively dual, triple, and quad independent outputs that are externally configurable with a simple circuit to provide positive and negative voltages for gate drive power. By being able to use just one device for powering all gate drives in a bridge application, the space saving achieved is a significant 33–50%. For example, in a three-phase bridge, the four-output MGJ63P provides isolated power for the three high-side switch drivers and a common rail for the three low-side switch drivers, potentially replacing up to six discrete DC–DC converters.

The DC-DC converters offer a wide 2:1 input voltage range with nominal inputs of 5V, 12V, and 24V and two, three, or four output channels of 24V are provided with high isolation between outputs. Exhibiting versatility, outputs can also be connected in parallel or series. Providing reliable operation in the fastest of switching systems, the devices are suitable for DC link voltages up to 3kVDC and feature a characterized dV/dt immunity of 80kV/microsecond and a characterized partial discharge performance that provides long service life.

The design of the DC-DC converters includes a planar transformer, short circuit and overload protection for robust operation under system fault conditions, and a very low coupling capacitance of typically 15pF that reduces system EMI problems. A frequency synchronization pin simplifies EMC filter design and an enable pin provides for power saving.

A pending application for UL60950 recognition for reinforced insulation will reduce the overall cost of system approval. Similarly, approvals for ANSI/AAMI ES60601-1, two MOOPs, and two MOPPs at different system voltage levels are pending and when attained will simplify system approval for medical applications. 

www.murata.com