Case Studies

Production Line FET Testing

Many high current switchmode DC to DC converters, particularly on computer motherboards, use two or more power FETs in parallel to increase efficiency or, in other words, reducing power loss to make products more eco-friendly or green. Keeping the amount of heat dissipation as low as possible also reduces the possibility of damaging the board, particularly if the airflow from the fan is restricted. Putting two similar devices in parallel theoretically reduces the power loss in each device by a factor of four. This means that the temperature rise in each device is a quarter of what it would be with one device, so the heatsink size can be reduced or the manufacturer can use surface mount devices instead to save space on the board.

Three Phase AC Variable Load

TRL, the UK's transport research laboratory were starting a project for the UK Highways Agency to measure the drag on a wheel caused by different road (pavement) surfaces and base courses to see which combinations might lead to better energy efficiency (lower carbon footprint), particularly for trucks. Their Pavement Test Facility PTF drives a truck wheel back and forth across a length of pavement at up to 20kph. The wheel mountings were instrumented with strain gauges but some method was needed to calibrate the readings.

Their engineers concluded that they needed a generator, geared up from the wheel and that this could then be loaded in a controlled way to vary the torque and thus the drag. PCM was approached to find a suitable generator, then to design and make an electronic load to suit. Calculations suggested that at 20kph, the maximum load would need to be 1kW and that being able to vary it in steps of zero, one third, two thirds or full power would provide the range of torque to perform the calibration.

Renewable Energy

A manufacturer of flexible photovoltaic or solar panels with a commitment to provide solar powered mobile (cell) phone chargers and LED lighting in Africa approached us to design and make several versions of high efficient battery charger circuits for different applications.

Our customer's photovoltaic panels produce useful charging current from relatively low incoming light levels so it is important that the circuit has a very low quiescent current drain. Under maximum lighting conditions our circuit also has very low losses compared with several competing products that our customer evaluated.