Load sensitive variable voltage motor controller
First Claim
Patent Images
1. A method for controlling the voltage applied to a load, comprising the steps of:
- receiving an AC line voltage;
generating an operating AC voltage from the AC line voltage;
applying said operating AC voltage across the load;
generating a first signal which is a function of the magnitude of said operating AC voltage;
generating a second signal representative of the magnitude of the AC current through the load;
generating a composite signal representative of a combination of said first and said second signals;
generating an average signal representative of the average value of said composite signal;
modifying said operating AC voltage in response to changes in said average signal.
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Abstract
An apparatus and method for controlling the voltage applied to an induction motor is taught. Load sensing is incorporated by monitoring the current through the motor, and combining that signal with a signal derived from the AC line voltage and AC voltage across the motor. This composite signal is averaged, with the resulting averaged signal being utilized to control a device for modulating voltage applied to the motor such as a phase control integrated circuit device.
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Citations
10 Claims
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1. A method for controlling the voltage applied to a load, comprising the steps of:
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receiving an AC line voltage; generating an operating AC voltage from the AC line voltage; applying said operating AC voltage across the load; generating a first signal which is a function of the magnitude of said operating AC voltage; generating a second signal representative of the magnitude of the AC current through the load; generating a composite signal representative of a combination of said first and said second signals; generating an average signal representative of the average value of said composite signal; modifying said operating AC voltage in response to changes in said average signal. - View Dependent Claims (2, 3, 4)
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5. A method for controlling the voltage applied to a load, comprising the steps of:
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receiving an AC line voltage; generating an operating AC voltage from the AC line voltage by switching off the AC line voltage to be applied to the load for a portion of each cycle such that the R.M.S. value of the operating AC voltage is below the R.M.S. value of the line voltage; applying the operating AC voltage across the load; generating a first signal which is a function of the instantaneous magnitude of said operating AC voltage applied to the load; generating a second signal representative of the instantaneous magnitude of the AC current through the Load; generating a composite signal representative of a combination of said first and said second signals; integrating said composite signal to generate an average signal; modifying the operating AC voltage by changing the portion of the AC line voltage cycle during which in the applied voltage is switched off in response to said average signal representative of the average value of said composite signal.
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6. An apparatus for controlling the voltage applied to a load comprising:
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terminal means for receiving an AC line voltage; means for generating an operating AC voltage from the AC line voltage; connector means for applying said operating AC voltage across the load; voltage detection means for generating a first signal which is a function of the magnitude of said operating AC voltage; current sensing means for generating a second signal representative of the magnitude of the AC current through the load; signal combining means for generating a composite signal representative of a combination of said first and said second signals; signal averaging means for generating an average signal representative of the average value of said composite signal; AC voltage modulation means for adjusting the operating AC voltage in response to said average signal. - View Dependent Claims (7, 8, 9)
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10. An apparatus for controlling the voltage applied to a load comprising:
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means for receiving an AC line voltage; means for generating an operating AC voltage from the AC line voltage by reducing the AC line voltage to be applied to the load for a portion of each cycle; means for applying said operating AC voltage across the load; voltage detection means for generating a first signal which is a function of the magnitude of said operating AC voltage; current sensing means for generating a second signal representative of the magnitude of the AC current through the load; signal combining means for generating a composite signal representative of a combination of said first and said second signals; signal averaging means for generating an average signal representative of the average value of said composite signal; AC voltage modulation means for modifying said generation of said operating AC voltage by changing said portion of the cycle during which in the applied voltage is reduced in response to said average signal.
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Specification