Chapter 15 Energy Efficiency of Electric Drives and Inverter-Motor
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Deleterious Effects of PWM Inverter Voltage Waveform on Motor Life q Derate motor (10%) because of increased losses q Large dv/dt • Insulation stress • Shaft currents (currents through bearings)
Summary/Review q What is the definition of energy efficiency of electric drives? q What are the various mechanisms of losses in motors, assuming a sinusoidal excitation? q How do the losses and the efficiency depend on motor speed, assuming a constant torque loading? q What are premium-efficiency motors? How much more efficient are they, compared to standard motors? q What are the effects of switching-frequency harmonics on the motor? How much should the motor be de-rated? q What is the typical range associated with the energy efficiency of power-processing units and of overall drives?
Summary/Review q Discuss the economics and the payback period of using premium-efficiency motors. q Describe the various deleterious effects of PWM-inverter output voltage waveforms. Describe the techniques for mitigating these effects.
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