System and method for controlling a latching relay failsafe
AssigneeParker-Hannifin Corporation
InventorsZachary R. Wright, Ted W. Sunderland
Life of this patent
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Abstract
A control circuit includes a latching relay, a power loss activation circuit, and a watchdog circuit. A microcontrol unit (MCU) communicates with the watchdog circuit in a normal operation of the control circuit. As an action of a failsafe precaution in the event of a main power loss or a component failure, the MCU stops communicating with the watchdog circuit, at which point the watchdog circuit instructs the power loss activation circuit to continue operation of the control circuit. The control circuit further operates to implement mitigation operations in the event of a main power loss or component failure.
Claims15
A control circuit, comprising:
- a relay including at least a first coil terminal and a second coil terminal;
- a first monitoring circuit having a first node coupled to a power supply input configured to activate the first coil terminal in the event of a power loss;
- a microcontrol unit (MCU), wherein, under a normal operation, the MCU operates to constantly reinforce a state of the relay;
- a watchdog circuit communicative with the MCU, wherein the watchdog circuit is configured to activate the first coil terminal in the event that the MCU stops communication with the watchdog circuit;
- and
- a power loss activation circuit that is electrically connected to the first monitoring circuit to provide backup power during a power loss;
- wherein the watchdog circuit comprises of a rising edge detector, a watchdog timer, a falling edge detector, and a pulse generator.
A method of driving a relay, comprising:
- monitoring an operation of a control circuit, wherein a microcontrol unit (MCU) communicates directly with a watchdog circuit, wherein, under a normal operation, the MCU operates to constantly reinforce a state of the relay;
- and
- activating the watchdog circuit in the event that communication of the MCU with the watchdog circuit ceases, wherein the watchdog circuit is configured to activate a first coil terminal of the relay by way of a first relay control circuit to control operation of a relay;
- wherein a first relay control circuit is comprised of a first node coupled to the first coil terminal, wherein the first relay control circuit is configured to energize the first coil terminal in the event of a power loss;
- wherein the watchdog circuit includes a rising edge detector and a watchdog timer, and an inputted signal passes through the rising edge detector to the watchdog timer during normal operation;
- and
- wherein the watchdog circuit further includes a falling edge detector and a pulse generator, the watchdog timer outputs a periodic signal to the falling edge detector which enables the pulse generator, at which point the signal is outputted to the first relay control circuit maintaining the relay in the failsafe state.
Dependencies are inferred from the claim text.