Title:
VARIABLE SPEED CONTROLLER FOR AIR MOVING APPLICATIONS USING AN ACINDUCTION MOTOR
Document Type and Number:
WIPO Patent Application WO2003007468
Kind Code:
A9
Abstract:
An HVAC system has at least one variable speed controller for an AC induction motor, especially of the Permanent Split Capacitor (PSC) type. The variable speed controller provides switched power via a modulating triac to the main coils of the motor and constant power via an on/off triac to the auxiliary coils during operation. A large value capacitor is placed in line with the auxiliary coils to reduce power consumption and current draw over that of known systems. Power to the motor can be turned off to provide for motor speed sensing through monitoring the frequency of a generated voltage when the power is turned off. Frequency-based motor speed sensing is accomplished by shutting off all current to the motor and measuring zero crossings on the generated voltage of the decaying magnetic field. The controller can be easily retrofitted onto existing motors. An optional controller bypass is provided to run the motor at rated speed in case of controller failure.
Inventors:
RATZ JAMES W
SIGAFUS PAUL E
LUTTON LARRY L
VRIONIS NICKOLAS G
SIGAFUS PAUL E
LUTTON LARRY L
VRIONIS NICKOLAS G
Application Number:
PCT/US2002/021700
Publication Date:
July 31, 2003
Filing Date:
July 10, 2002
Export Citation:
Assignee:
VARIDIGM CORP (US)
International Classes:
F23N1/06; H02P1/42; H02P1/44; H02P25/04; F23N3/08; (IPC1-7): H02P7/622; D06F37/30; F23N1/06; H02P1/42; H02P1/44; H02P7/62
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