DC Current Transformer Using Class-D Compensating Amplifier

What is it about?

Classical DC current transformer, based on a linear amplifier as a compensating amplifier, is well-known as a power inefficient device. If the linear amplifier is replaced with switching counterpart, significant power saving can be achieved. Natural choice for replacement can be found in a half-bridge class-D amplifier. However, half-bridge class-D amplifier is prone to bus-pumping effect, and direct replacement cannot be performed in a straight forward manner. This study presents analysis of power consumption issues and irregular behaviour for a DC current transformer, caused by the bus-pumping effect. For the case of DC current measurement, the main issues are explained, giving better insight to power consumption, and possible hazards to transformer circuitry. Presented analytical results are experimentally verified.

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