Actuator power control circuit having fail-safe bypass switching
First Claim
1. A power control system comprising:
- a switching circuit; and
a digital controller connected to the switching circuit; and
wherein;
the switching circuit controls an amount of current from a power supply to an actuator according to a control signal from the controller;
if the controller fails to provide the control signal to the switching circuit then the switching circuit controls the amount of current from the power supply to the actuator according to a default control signal; and
the actuator is a component of a heating, ventilating and air conditioning system.
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Accused Products
Abstract
A system for controlling power to actuators. For example, a controller may output a signal having a variable duty cycle waveform for controlling current to an actuator via an interface circuit between the controller and the actuator. Changing the duty cycle may change the amount of current to the actuator. The controller may provide a control signal that optimizes power consumption by the actuator for efficiency purposes. However, if the controller fails, then no control signal may be available to allow current to the actuator, particularly in situations where the actuator may need to be operationally tested. To avoid such situations, fail-safe bypass switching may be incorporated into the interface circuit. Upon absence of a control signal from the controller, the circuit may provide a default signal in lieu of the control signal to maintain current to the actuator.
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Citations
19 Claims
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1. A power control system comprising:
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a switching circuit; and a digital controller connected to the switching circuit; and wherein; the switching circuit controls an amount of current from a power supply to an actuator according to a control signal from the controller; if the controller fails to provide the control signal to the switching circuit then the switching circuit controls the amount of current from the power supply to the actuator according to a default control signal; and the actuator is a component of a heating, ventilating and air conditioning system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for control of power to an actuator, comprising:
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varying an amount of electrical power to an actuator; and switching the electrical power on and off from an electrical power source to the actuator to provide the varying an amount of power to the actuator; and wherein; the switching the electrical power is according to a control signal; a controller outputs the control signal; and if the controller outputs no control signal, then a default signal is provided in lieu of the control signal. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A power control circuit for an actuator comprising:
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an actuator; a fail-safe bypass switching circuit connected to the actuator; a power supply connected to the fail safe bypass switching circuit; and a controller connected to the fail-safe bypass switching circuit; and wherein; the actuator comprises a motor winding; the power supply provides a power signal to the a fail-safe bypass switching circuit; the controller provides a control signal to the fail-safe bypass switching circuit; the fail-safe bypass switching circuit outputs the power signal having a waveform resembling a waveform of the control signal; and if the controller fails to provide a control signal, then the fail-safe bypass switching circuit provides a second control signal in lieu of the control signal from the controller. - View Dependent Claims (19)
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Specification