Power converters are used to transfer power from a source to a load using a different type or level of electrical power.
These power converters e.g. inverters, active rectifiers, DC-DC converters etc. include high power semiconductor switching devices such as FETs, MOSFETs, IGBTs, etc. A power semiconductor switching device requires sufficient power applied to its input to perform its switching tasks, in time and in steady state. Many of these high power switching devices utilise a gate driver to turn them on and off. A power supply provides the required voltage to the gate driver electronics. The gate driver electronics provide the logic state to the power devices. The power to the input of power device is applied through the output switching stage.
The gate drive electronics provides protection functions etc. as well. The complete gate driver electronics act as the interface between the low voltage electronics and the high voltage power electronics.
It is often necessary to galvanically isolate the low voltage and high voltage sides for functional and safety reasons. There is also a need to minimise current and voltage fed back into the logic elements, which can undesirably affect the drive elements or can produce spurious logic circuit glitches. Often, the two sides are provided with isolated electronics and power supplies to provide electrical isolation between the two subsystems.
A problem with gate drivers designed in this way is that they may be subject to stray parasitic inductance or capacitance which can cause noise coupling from the power circuit to the control logic and can increase electromagnetic interference (EMI) and non-deterministic behaviour of the system.
Digital isolators are available, but these require a dedicated isolated power supply, which increases the overall weight and cost of the system.
Other solutions do exist for isolation, such as opto-couplers, but these are not suitable for high reliability, high temperature and high noise systems as required in aerospace applications, and these solutions also require independent electronics and power supplies.