Ideal voltage controller for conserving energy in inductive loads

An apparatus for controlling the voltage applied to inductive load comprising:

• 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 inductive load for a portion of each half-cycle thereof, each reduced-voltage portion beginning when the current through the load is substantially zero;
• means for applying said operating AC voltage across the load;
• voltage detection means for generating an electronic measured signal which is a function of the magnitude of said operating AC voltage;
• signal averaging means for generating an average signal representative of the average value of said electronic measured signal;
• AC voltage modulation means for modifying said generation of said operating AC voltage by changing the length of each voltage-reduction portion in response to said average signal.

A method for controlling the voltage applied to inductive load, comprising the steps of:

• 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 inductive load for a portion of each half-cycle thereof such that the R.M.S. value of the operating AC voltage is below the R.M.S. value of the line voltage, each switched-off portion beginning when the current through the load is substantially zero;
• applying the operating AC voltage across the load;
• generating an electronic measured signal which is a function of the instantaneous magnitude of said operating AC voltage applied to the load;
• electronically integrating said measured signal to generate an average signal;
• modifying the operating AC voltage by changing the length of each switched-off portion in response to said average signal.

An apparatus for controlling the voltage applied to an electric motor comprising:

• 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 applied to the motor for a portion of each half-cycle thereof, each reduced-voltage portion beginning when the current through the motor is substantially zero;
• means for applying said operating AC voltage across the motor;
• voltage detection means for generating a measured signal as a function of the magnitude of the instantaneous value of said operating AC voltage;
• signal averaging means for generating an average signal representative of the average value of said electronic measured signal;
• modulation means for modifying said generation of said operating AC voltage by changing the length of each voltage-reduction portion in response to said average signal;
• and
• a coupling circuit for coupling said measured signal to said signal averaging means and for modifying said measured signal such that the RMS value of the operating AC voltage increases with increasing motor loading.

An apparatus for controlling the voltage applied to an inductive load comprising:

• 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 inductive load;
• voltage detection means for generating an electronic measured signal which is a function of the magnitude of said operating AC voltage;
• signal averaging means for generating an average signal representative of the average value of said electronic measured signal;
• AC voltage modulation means for adjusting the operating AC voltage in response to changes in said average signal by reducing the magnitude of said operating AC voltage below the line voltage for a portion of each AC voltage half-cycle, each portion beginning when the current through the inductive load is substantially zero, the length of said portion being determined by said average signal.

An apparatus for controlling the voltage applied to an electric motor comprising:

• 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 applied to the electric motor for a portion of each half-cycle thereof, each reduced-voltage portion beginning when the current through the motor is substantially zero;
• means for applying said operating AC voltage across the motor;
• voltage detection means for generating an electronically measured signal as a function of the magnitude of the operating AC voltage;
• signal averaging means for generating an average signal representative of the average value of said electronically measured signal;
• and
• modulation means for modifying said generation of said operating AC voltage by changing the length of each reduced-voltage portion in response to said average signal;
• and
• wherein said voltage detection means comprises circuitry, including a capacitor means, responsive to changes in the loading of the motor for modifying said measured signal to increase the RMS value of the operating AC voltage with increasing motor loading.

An apparatus for controlling the voltage applied to an inductive load comprising:

• 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 applied to the load for a portion of each half-cycle thereof, each reduced-voltage portion beginning when the current through the load is substantially zero;
• means for applying said operating AC voltage across the load;
• voltage detection means for generating an electronically measured signal as a function of the magnitude of the operating AC voltage;
• signal averaging means for generating an average signal representative of the average value of said electronically measured signal, said average signal being related to the RMS value of said operating AC voltage;
• and
• modulation means for modifying said generation of said operating AC voltage by changing the length of each reduced-voltage portion in response to said average signal;
• and
• wherein said voltage detection means comprises electronic means for modifying said measured signal such that said average signal is more closely related to the RMS value of said operating AC voltage than the unmodified average signal.

An apparatus for controlling the voltage applied to an inductive load comprising:

• 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 applied to the load for a portion of each half-cycle thereof, each reduced-voltage portion beginning when the current through the load is substantially zero;
• means for applying said operating AC voltage across the load;
• voltage detection means for generating a measured signal as a function of the magnitude of the instantaneous value of said operating AC voltage;
• signal averaging means for generating an average signal representative of the average value of said electronic measured signal and having a correspondence to the RMS value of said operating AC voltage;
• a coupling circuit for coupling said measured signal to said signal averaging means and for modifying said measured signal to improve the correspondence of said average signal to the RMS value of said operating AC voltage;
• and
• modulation means for modifying said generation of said operating AC voltage by changing the length of each voltage-reduction portion in response to said average signal.