Control circuits for supplying current to actuate solenoids
Disclosed are exemplary embodiments of control circuits for supplying current to actuate solenoids, such as refrigerant valves in HVAC systems, other valves, “solenoid” style contactors, other coil driven actuators, etc. In exemplary embodiments, a control circuit for supplying current to actuate a solenoid comprises a solenoid coil and a switch coupled with the solenoid coil. The control circuit may be configured such that the solenoid coil is operable as a load coil and a switch mode supply coil and such that the switch is configured to operate a load and power supply of the control circuit. Additionally, or alternatively, the control circuit may include a current monitoring shunt and a flyback diode that are located in a circulating current loop defined by and/or including the solenoid coil, the current monitoring shunt, and the flyback diode.
1. A control circuit for supplying current to actuate a solenoid, the control circuit comprising a solenoid coil and a switch coupled with the solenoid coil, wherein:
the control circuit is configured such that the solenoid coil is operable as a load coil and a switch mode supply coil and such that the switch is configured to operate a load and power supply of the control circuit; and
the control circuit includes a current monitoring shunt and a flyback diode that are located in a circulating current loop defined by and/or including the solenoid coil, the current monitoring shunt, and the flyback diode.
2. The control circuit of claim 1 , wherein the control circuit is configured to be operable for monitoring full current through the solenoid coil including a circulating current via the current monitoring shunt located in the circulating current loop.
3. The control circuit of claim 1 , wherein the current monitoring shunt comprises a current sense resistor coupled in series with the solenoid coil and the flyback diode in the circulating current loop.
4. The control circuit of claim 1 , wherein:
the control circuit comprises a switched mode current supply including a pulse width modulation (PWM) and/or pulse position modulation (PPM) duty cycle; and
the control circuit is configured to be operable to:
increase the PWM and/or PPM duty cycle, via controlling the switch to have longer duration pulses, to thereby increase the current supplied to the solenoid coil in response to determining that the current supplied to the solenoid coil is too low; and
decrease the PWM and/or PPM duty cycle, via controlling the switch to have shorter duration pulses, to thereby decrease the current supplied to the solenoid coil in response to determining that the current supplied to the solenoid coil is too high.
5. The control circuit of claim 1 , wherein:
the control circuit comprises a switched mode current supply including a pulse width modulation (PWM) and/or pulse position modulation (PPM) duty cycle; and
the control circuit is configured to be operable for adjusting the PWM and/or PPM duty cycle, via controllably adjusting a pulse duration of the switch, when switching between a first current supplied to the solenoid coil and a second current, lower than the first current, supplied to the solenoid coil.
6. The control circuit of claim 1 , wherein:
the solenoid coil is adapted to selectively open and close a valve; and
the control circuit is configured to be operable for adjusting a pulse width modulation (PWM) and/or pulse position modulation (PPM) duty cycle, via controllably adjusting a pulse duration of the switch, when switching between a first current supplied to the solenoid coil for opening the valve and a second current, lower than the first current, supplied to the solenoid coil for holding the valve open.
7. The control circuit of claim 1 , wherein the control circuit includes a pulse width modulation (PWM) and/or pulse position modulation (PPM) current solenoid controller coupled with the switch and the solenoid coil, whereby the PWM and/or PPM current solenoid controller is configured to be operable for adjusting the PWM and/or PPM duty cycle, via controllably adjusting a pulse duration of the switch, when switching between a first current supplied to the solenoid coil and a second current, lower than the first current, supplied to the solenoid coil.
8. The control circuit of claim 1 , wherein the control circuit includes a pulse width modulation (PWM) and/or pulse position modulation (PPM) current solenoid controller coupled with the switch and the solenoid coil such that the switch drives both the solenoid coil and a controller power supply.
9. The control circuit of claim 1 , wherein the control circuit is configured to treat the solenoid coil as the load and inductive element.
10. The control circuit of claim 1 , wherein the switch is coupled with a boot-up circuit and an isolated coupler configured to be operable for providing isolation between high voltage components and lower voltage components of the control circuit.
11. The control circuit of claim 1 , wherein:
the control circuit includes a driver configured to control current levels, timing, and switching;
the driver is configured to adjust reference voltage over time to thereby provide a pick function for the solenoid; and
the driver is coupled with an optocoupler configured to disable the driver when a comparator determines, via sensed current, that voltage on the current monitoring shunt in the circulating current loop is above a reference voltage.
12. The control circuit of claim 1 , wherein the control circuit includes a driver and an isolated coupler coupled in series between the driver and the switch, the isolated coupler configured to be operable for providing isolation between the driver and lower voltage components of the control circuit.
13. The control circuit of claim 1 , wherein the control circuit includes a driver coupled with the switch and the solenoid coil, the driver is configured to be operable as or perform the function of a comparator, perform pulse width modulation (PWM) and/or pulse position modulation (PPM) control, and interface with the solenoid coil.
14. The control circuit of claim 1 , wherein:
the control circuit includes a rectifier coupled with the switch; and
the switch is configured to be coupled with the power supply via the rectifier for supplying to the solenoid coil via the switch.
15. A valve assembly comprising a valve and the control circuit of claim 1 , wherein the solenoid coil is adapted to selectively open and close the valve, and wherein the control circuit is configured to be operable for adjusting a pulse width modulation (PWM) and/or pulse position modulation (PPM) duty cycle when switching between a first current supplied to the solenoid coil for opening the valve and a second current, lower than the first current, supplied to the solenoid coil for holding the valve open.
16. A control circuit for supplying current to actuate a solenoid, the control circuit comprising a solenoid coil and a switch coupled with the solenoid coil, wherein the control circuit is configured such that the solenoid coil is operable as a load coil and a switch mode supply coil and such that the switch is configured to operate a load and power supply of the control circuit.
17. The control circuit of claim 16 , wherein:
the control circuit comprises a switched mode current supply including a pulse width modulation (PWM) and/or pulse position modulation (PPM) duty cycle; and
the control circuit is configured to be operable to:
increase the PWM and/or PPM duty cycle, via controlling the switch to have longer duration pulses, to thereby increase the current supplied to the solenoid coil in response to determining that the current supplied to the solenoid coil is too low; and
decrease the PWM and/or PPM duty cycle, via controlling the switch to have shorter duration pulses, to thereby decrease the current supplied to the solenoid coil in response to determining that the current supplied to the solenoid coil is too high.
18. The control circuit of claim 16 , wherein:
the control circuit comprises a switched mode current supply including a pulse width modulation (PWM) and/or pulse position modulation (PPM) duty cycle; and
the control circuit is configured to be operable for adjusting the PWM and/or PPM duty cycle, via controllably adjusting a pulse duration of the switch, when switching between a first current supplied to the solenoid coil and a second current, lower than the first current, supplied to the solenoid coil.
19. The control circuit of claim 16 , wherein:
the solenoid coil is adapted to selectively open and close a valve; and
the control circuit is configured to be operable for adjusting a pulse width modulation (PWM) and/or pulse position modulation (PPM) duty cycle, via controllably adjusting a pulse duration of the switch, when switching between a first current supplied to the solenoid coil for opening the valve and a second current, lower than the first current, supplied to the solenoid coil for holding the valve open.
20. The control circuit of claim 16 , wherein the control circuit includes a pulse width modulation (PWM) and/or pulse position modulation (PPM) current solenoid controller coupled with the switch and the solenoid coil, whereby the PWM and/or PPM current solenoid controller is configured to be operable for adjusting the PWM and/or PPM duty cycle, via controllably adjusting a pulse duration of the switch, when switching between a first current supplied to the solenoid coil and a second current, lower than the first current, supplied to the solenoid coil.
21. The control circuit of claim 16 , wherein the control circuit includes a pulse width modulation (PWM) and/or pulse position modulation (PPM) current solenoid controller coupled with the switch and the solenoid coil such that the switch drives both the solenoid coil and a controller power supply.
22. The control circuit of claim 16 , wherein the control circuit is configured to treat the solenoid coil as the load and inductive element.
23. A valve assembly comprising a valve and the control circuit of claim 16 , wherein the solenoid coil is adapted to selectively open and close the valve, and wherein the control circuit is configured to be operable for adjusting a pulse width modulation (PWM) and/or pulse position modulation (PPM) duty cycle when switching between a first current supplied to the solenoid coil for opening the valve and a second current, lower than the first current, supplied to the solenoid coil for holding the valve open.