Improvements made to brushless pump drives

Due to new design, control and production technology innovations, brushless drives for pumps and fan systems work more efficiently and quietly. Electrical appliance users and the automotive industry stand to reap enormous potential benefits.

Small electric motors are found in many household appliances, tools, computers and modern cars. They usually drive auxiliary units such as pumps and fans. Although each motor does not consume much energy individually, they offer a significant savings potential.

The research team of the recently completed CD Laboratory for Brushless Drives for Pump and Fan Applications, headed by Annette Mütze from the Electric Drives and Power Electronic Systems Institute at Graz University of Technology (TU Graz), has now further tapped into this potential. Thanks to innovative design, modified control technology and new manufacturing techniques, the brushless integrated drives developed at the laboratory are lighter, consume less energy and operate more quietly.

Larger claw pole motors are used in vehicle lighting systems. Their use as small drive units is less well known. The research team has reduced these small drives’ so-called cogging torques by skewing and slotting the claws, which does not incur additional costs. This minimises the momentary engagement of the claws when the motor is turned, thus reducing unwanted vibrations.

“This enabled us to reduce an important noise source by 70 per cent. This means that the drives run much more smoothly and quietly,” Ms Mütze said.

Efficiency gains are achieved through simplified regulation of the current flow. Pulse width modulation usually regulates the current supplied to the motor of a fan or pump. For the current to flow in the desired rectangular pattern, many switching operations are required, which causes additional energy consumption.

“We only switch our drives on and off once per desired rectangle,” Ms Mütze said. “This enabled us to considerably reduce the additional energy consumption caused by switching losses.”

Therefore, these drives have much better overall efficiency, particularly at low currents, than those controlled via conventional pulse width modulation. Due to the drastically reduced number of switching operations, the motors’ circuit boards also require half as many capacitors, which reduces costs.

The third innovation is the implementation of PCB motors with ferrite cores. PCB stands for printed circuit board. In the case of motors, the windings that generate the magnetic field required for the drive are designed as printed circuit boards. This allows a high degree of automation in production. The research team equipped the circuit boards with 3D-printed ferrite cores, which improved the guidance of the magnetic flux in the motors. This was the prerequisite for using more cost-effective magnets, which are also based on ferrite.

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