Method of controlling preheating power and mechanism for providing preheating
AssigneeDaikin Industries, Ltd.
InventorsHiroshi Dohmae, Tomoisa Taniguchi
Life of this patent
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Abstract
The present invention relates to a motor and especially to a technique for maintaining constant power consumption in preheating a compressor motor in an air conditioner. An object thereof is to permit constant preheating of the motor irrespective of variations in receiving voltage. To accomplish this object, switching control of an inverter (15) that applies a three-phase current to a motor (30) is performed by a control circuit (20) in accordance with a duty based on detected values of voltage (Vm) and current (Im). This duty decreases with increasing receiving voltage.
Claims14
A method of controlling preheating power applied to a polyphase motor comprising:
- coupling said polyphase motor to an inverter (15),
- applying current from said inverter to a winding (LU, LW) of said polyphase motor in open-phase operation for preheating said polyphase motor,
- said current being applied during a predetermined period (T) in which said polyphase motor does not rotate, with a duty cycle (D) that is a ratio between time during which current is applied and said period, and
- varying the duty cycle inversely with respect to a change in a DC voltage (Vm) applied to said inverter.
A preheating system comprising:
- a polyphase motor, and
- an operation control unit for operating said polyphase motor open-phase to generate heat, wherein said operation control unit includes an inverter (15),
- said inverter applying current to said polyphase motor during a predetermined period (T), in which said polyphase motor does not rotate, with a duty cycle (D) that is a ratio between time during which current is applied and said period, and the duty cycle varies inversely with respect to a change in a DC voltage (Vm) applied to said inverter.
Dependencies are inferred from the claim text.