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Electric Motor ManufactureDesign and Development

Manufacturer’s fight with vibration to keep electric motor production line running.
A large-capacity inverter type power supply with a low-ripple current and low noise solves problems.

Power supplies, used to do performance and aging testing during product development, are an indispensable part of the power electronics market. As communications equipment, household appliances, automotive devices, aviation equipment and other electronic devices go on increase the Electric capacity, and there is an increasing demand for high-power supplies.

The Problem

The team was trying to address motor vibrations. But it was unable to isolate the torque ripples produced by the motors themselves.

This case involves a company that supplies motors to a range of manufacturers. The company received a complaint from one of its customers about motor vibration. The head of the company’s design and development division explains:

“Our client told us to look into the issue of a motor we had supplied it with that was exhibiting vibration. The design and development division tried to find the cause on the case straight away.”

The team first tested the motor using an inverter power supply. However, the testing was more difficult than they expected.

“The output of pulse width modulation (PWM) inverters is characterized by a switching ripple current superimposed on the output waveform. Because the torque of the motor is also affected by ripple current from the inverter, we were unable to isolate the torque ripple attributable to the motor itself. This meant that our tests were unable to determine whether the problem was caused by the motor, the inverter, or the controller.”

As time ticked on with no solution in sight, the team became increasingly uneasy.

“If we didn’t identify the cause soon, we would be forced to shut down the motor manufacturing line. I was anxious and felt the need to identify the cause as soon as possible,” recalls the divisional head.

Key Aspects of the Problem

  • The PWM inverter was producing a ripple current.

  • Due to the ripple current from the inverter superimposed on the motor input, it was not possible to separately identify any torque ripple attributable to the motor itself.

  • The team could not determine whether it was the motor that was responsible for the vibration.

How was this problem solved?