Ametek Rotron

Basil Issac

Leslie W Yoho

Matthew Clark

David D Heberle

Arthur Tong

Disclosed is an AC motor drive () for a three phase, 400 Hz., AC induction motor. The application is a constant speed, constant load application. An AC power source with a wide variation in voltage and frequency is rectified to establish a DC bus. A three phase full wave bridge inverter operates on this source. A cascaded sinusoidal reference signal generator () generates three sinusoidal voltages 120&#xb0; phase shifted from one another. These pure sinusoidal reference help reduce harmonic currents. A high PWM frequency is used to operate the power switches of the bridge to reduce current harmonics. The speed regulator () generates an error voltage between a speed command voltage and a feedback of DC voltage that is equivalent to the RMS value of the terminal voltage of the motor for speed regulation. The harmonic content of the DC bus current is extracted to provide short circuit protection.

Three phase AC motor drive

Disclosed is a three phase Vienna converter for converting three phase AC to DC, with active power factor control. Further the control electronics is galvanically isolated from the neutral of the input three phase supply and also from the center terminal of the two series connected output DC filter capacitors. The control circuit is built completely with analog devices to meet stringent electromagnetic interference standards. The converter is capable of operating over a wide range of voltages and frequencies of the input supply voltage.

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Whitefield, India

Basil Issac