Automated Efficiency Testing of Converter-Fed Induction Motors

The determination of additional harmonic losses in converter-fed induction motors (IMs) is often problematic as evidenced by the conflicting reports cited in literature. Although this can be attributed to several factors, the mismatch in test points owing to mechanical loading and other non-idealities due to the human operator are issues that can be addressed. This paper presents an automated efficiency testing approach for converter-fed IMs, based on the IEC/TS 60034-2-3. The procedure has been developed to minimize human-induced errors in the determination of additional harmonic losses by ensuring the sinusoidal and PWM supply tests are performed under identical conditions. Analysis of the experimental results obtained by testing a 55kW IM highlight some improvements in the quality of test results due to the proposed automated testing.