For the purposes of the EU co-funded project DEEP PPU, consortium partner FRAZA has developed an advanced Zero Current Detection Sensor (ZCD sensor) having an extremely low latency, volume and losses.
Developmental process of the Zero Current Detection Sensor
The most suitable yet simple concept of zero current detection utilizes a small transformer driven into saturation. This concept hides significant potential of achieving very low losses, a good noise immunity, high accuracy and fast responsiveness. The concept operates by detecting the moment of the magnetic core falling out of the saturation at the moment of the current changing the polarity. The change in flux of the magnetic core induces voltage in a detection coil which is then reflected in a form of a voltage pulse.
The challenges of such a design are primarily low losses and low latency. Facing these challenges FRAZA developed three prototypes. The first prototype was built to prove the concept. The latency was still large (~100 ns) and strongly dependent on the current’s first derivative. The second prototype improved the latency to approximately 10 ns and reduced the latency dependence. This prototype has an additional in-built housing for an effective heat dissipation. Finally, the third prototype reduced the losses by 90% and introduces a cost-effective serial production.
Properties of the ZCD Sensor
Outstandingly good properties are achieved by the third prototype of the ZCD sensor developed by FRAZA. The dimensions of the sensor are 6 mm x 6 mm x 1 mm. It achieves latency between 7 ns and 15 ns while simultaneously having losses below 100 mW at 1 MHz and 50 App.
