Method of and apparatus for reducing energy consumption
AssigneeDavis Controls Corporation
InventorKevin D. Kral
Life of this patent
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Abstract
The proposed invention is an energy saving load control device primarily intended for inductive loads (i.e., fluorescent lighting, motors, etc.) operating from an alternating current (AC) source. The proposed device switches the load voltage off at arbitrary positions in the sine wave and simultaneously provides a commutating path for any inductive current. By switching the load voltage on and off and providing a commutating current path reduced energy consumption is realized.
Claims20
A control device for an inductive load comprising:
- a normally operated load switch connected between a source of alternating current and an inductive load;
- a normally inoperative commutating switch connected across said load;
- a controller circuit;
- a monitor circuit connected between said alternating current source and said controller, operated in response to a zero crossing of said alternating current from a positive half-cycle to a negative half-cycle, or in the alternative, from a negative half-cycle to a positive half-cycle to initiate sequential operation of said controller;
- said operated controller after a first predetermined period of time rendering said load switch inoperative and rendering said commutating switch operated.
The method of periodically interrupting each cycle of an alternating current voltage to control the amount of current flowing through an inductive load, comprising the steps of:
- monitoring said alternating current voltage for a zero crossing of said voltage from a positive half-cycle to a negative half-cycle, or in the alternative for a zero crossing, from a negative half-cycle to a positive half-cycle;
- in response to each zero crossing, controlling a load switch after a first predetermined period of time to interrupt conduction of said voltage to said load and to operate an associated commutating switch to place a short circuit across said load;
- after a second predetermined period of time, controlling said load switch to conduct said voltage to said inductive load and render said commutating switch inoperative;
- after a third predetermined period of time, controlling said load switch to again interrupt said voltage conducted to said load and control said commutating switch to again place a short circuit across that load;
- after a fourth predetermined period of time, controlling said load switch to again conduct said voltage to said load and render said commutating switch inoperative;
- and repeating each of the preceding steps in the given sequence for each zero crossing of said current from a positive half-cycle to a negative half-cycle or in the alternative for each zero crossing of said current from a negative half-cycle to a positive half-cycle.
Dependencies are inferred from the claim text.