Circuit and method for controlling current flow through a solenoid

• US 6,850,402 B2
• Filed: 03/01/2002
• Issued: 02/01/2005
• Est. Priority Date: 03/01/2002
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Ahrendt, Terry J.
• Primary Examiner(s): Reichard, Dean A.
• Assistant Examiner(s): HARRIS, ANTON B
• Application Number:
  US10/087,632
• Publication Number:
  US 20030165038A1
• Time in Patent Office: 1,068 Days
• Field of Search: 361/152, 361/154, 361/160, 361/166, 307/141.8, 327/396, 327/401
• US Class Current: 361/152
• CPC Class Codes: H01H 47/325 by switching regulator
• CPC Class Codes: H02H 9/047 Free-wheeling circuits

Abstract

A solenoid control circuit that includes two switching networks that are selectively opened and closed in a current limit cycle to control the magnitude of the current flowing through the solenoid. The configuration of the switching networks is such that current flows through an energy dissipating resistor only when the solenoid is commanded off by the solenoid control circuit, and not during the current limit cycle. Thus, the energy dissipated by this resistor is reduced relative to other solenoid control circuits, making it more efficient, and reducing EMI emissions from the circuit while providing for a fast solenoid response.

Claims

1. A circuit for controlling current flow through a solenoid, comprising:

a first controllable switch electrically coupled in parallel with a first resistive element;

a second controllable switch electrically coupled in series with a second resistor;

a diode electrically coupled in series between the first controllable switch and the second controllable switch; and

a controller circuit operable to (i) selectively open and close the first controllable switch and the second controllable switch in response to a command signal and (ii) selectively open and close the second controllable switch based on a magnitude of current flow through the solenoid.

2. The circuit of claim 1, wherein the controller circuit comprises:

a comparator circuit having at least a first input terminal coupled to a reference voltage, a second input terminal coupled to receive a voltage signal representative of a current magnitude flowing through the solenoid, and a third input terminal coupled to receive the command signal, the comparator operable to supply a switch control signal based on the signals on the first, second, and third input terminals; and

a driver circuit having at least a first input coupled to receive the switch control signal and operable, in response thereto, to selectively open and close the second controllable switch.

3. The circuit of claim 2, wherein the driver circuit further has at least a second input coupled to receive the command signal and operable, in response thereto, to selectively open and close the first controllable switch and the second controllable switch.

4. The circuit of claim 3, wherein the controller circuit further comprises an input circuit operable to condition the command signal and supply the conditioned command signal to the driver circuit second input and the comparator circuit third input.

5. The circuit of claim 2, wherein the comparator circuit comprises:

a comparator having a first comparator input terminal electrically coupled to the comparator circuit first input terminal and a second comparator input terminal electrically coupled to the comparator circuit second input terminal, and a comparator output terminal; and

a logical AND circuit having a first AND circuit input coupled to the third comparator circuit input and a second AND circuit input coupled to the comparator output terminal and operable, in response thereto, to supply the switch control signal.

6. The circuit of claim 2, wherein the controller circuit further comprises:

a solenoid current monitoring circuit electrically coupled to receive a signal representative of current magnitude flowing through the solenoid and operable, in response thereto, to supply the voltage signal representative of a current magnitude flowing through the solenoid.

7. The circuit of claim 6, wherein the solenoid current monitoring circuit comprises:

an amplifier circuit electrically coupled to receive the signal representative of the current magnitude flowing through the solenoid and operable to provide an amplified current magnitude signal; and

a timing circuit coupled to receive the amplified current magnitude signal and operable to supply the a voltage signal representative of a current magnitude flowing through the solenoid.

8. The circuit of claim 1, wherein the controller supplies a first switch control signal to cause the first controllable switch to selectively open and close and a second switch control signal to cause the second controllable switch to open and close.

9. The circuit of claim 8, wherein:

the first controllable switch comprises a first MOSFET having at least a gate terminal electrically coupled to receive the first switch control signal, a source terminal electrically coupled to one terminal of the first resistive element, and a drain terminal electrically coupled to another terminal of the first resistive element; and

the second controllable switch comprises a second MOSFET having at least a gate terminal electrically coupled to receive the second switch control signal, a source terminal electrically coupled to one terminal of the second resistor, and a drain terminal electrically coupled to a terminal of the diode.

10. The circuit of claim 1, wherein:

current flows through the solenoid, the second controllable switch, and the second resistor when the first controllable switch and the second controllable switch are closed; and

current flows through the solenoid, the diode, and the first controllable switch when the first controllable switch is closed and the second controllable switch is open.

11. The circuit of claim 10, wherein current flows through the solenoid, the diode, and the first resistive element when the first and second controllable switches are open after the being closed simultaneously for a predetermined time period.

12. The circuit of claim 1, further comprising:

a solenoid electrically coupled in parallel with the first controllable switch and the diode.

13. A circuit for controlling current flow through a solenoid, comprising:

a diode having at least a first diode terminal and a second diode terminal;

a first controllable switch electrically coupled in series between the first diode terminal and a first circuit terminal, the first circuit terminal adapted for coupling the circuit to a first predetermined voltage magnitude;

a first resistive element having at least a first resistive element terminal and a second resistor terminal, the second resistor terminal electrically coupled to a second circuit terminal that is adapted for coupling the circuit to a second predetermined voltage magnitude;

a second controllable switch electrically coupled in series between the second diode terminal and the first resistive element terminal; and

a controller circuit having at least a first input coupled to receive a command signal and operable to (i) selectively open and close the first controllable switch and the second controllable switch in response to the command signal and (ii) selectively open and close the second controllable switch based on a magnitude of current flowing through the solenoid.

14. The circuit of claim 13, wherein the controller circuit comprises:

a comparator circuit having at least a first input terminal coupled to a reference voltage, a second input terminal coupled to receive a voltage signal representative of a current magnitude flowing through the solenoid, and a third input terminal coupled to receive the command signal, the comparator operable to supply a switch control signal based on the signals on the first, second, and third input terminals; and

a driver circuit having at least a first input coupled to receive the switch control signal and operable, in response thereto, to selectively open and close the second controllable switch.

15. The circuit of claim 14, wherein the driver circuit further has at least a second input coupled to receive the command signal and operable, in response thereto, the selectively open and close the first controllable switch and the second controllable switch.

16. The circuit of claim 15, wherein the controller circuit further comprises an input circuit operable to condition the command signal and supply the conditioned command signal to the driver circuit second input and the comparator circuit third input.

17. The circuit of claim 14, wherein the comparator circuit comprises:

a comparator having a first comparator input terminal electrically coupled to the comparator circuit first input terminal and a second comparator input terminal electrically coupled to the comparator circuit second input terminal, and a comparator output terminal; and

a logical AND circuit having a first AND circuit input coupled to the comparator output terminal and operable, in response thereto, to supply the switch control signal.

18. The circuit of claim 14, wherein the controller circuit further comprises:

a solenoid current monitoring circuit electrically coupled to receive a signal representative of current magnitude flowing through the solenoid and operable, in response thereto, to supply the voltage signal representative of the current magnitude flowing through the solenoid.

19. The circuit of claim 18, wherein the solenoid current monitoring circuit comprises:

an amplifier circuit electrically coupled to receive the signal representative of the current magnitude flowing through the solenoid and operable to provide an amplified current magnitude signal; and

a timing circuit coupled to receive the amplified current magnitude signal and operable to supply the voltage signal representative of the current magnitude flowing through the solenoid.

20. The circuit of claim 14, wherein the controller supplies a first switch control signal to cause the first controllable switch to selectively open and close and a second switch control signal to cause the second controllable switch to open and close.

21. The circuit of claim 20, wherein:

the first controllable switch comprises a first MOSFET having at least a gate terminal electrically coupled to receive the first switch control signal, a source terminal electrically coupled to one terminal of the first resistive element, and a drain terminal electrically coupled to another terminal of the first resistive element; and

the second controllable switch comprises a second MOSFET having at least a gate terminal electrically to receive the second switch control signal, a source terminal electrically coupled to one terminal of the second resistor, and a drain terminal electrically coupled to a terminal of the diode.

22. The circuit of claim 13, wherein:

the current flowing through the solenoid flows through the second controllable switch and the second resistor when the first controllable switch and the second controllable switch are closed; and

the current flowing through the solenoid, flows through the diode and the first controllable switch when the first controllable switch is closed and the second controllable switch is open.

23. The circuit of claim 22, wherein the current flowing through the solenoid, flows through the diode and the first resistive element when the first and second controllable switches are open after the being closed simultaneously for a predetermined time period.

24. The circuit of claim 13, further comprising:

a solenoid coupled electrically coupled in parallel with the first controllable switch and the diode.

25. A circuit for controlling current flow through a solenoid, comprising:

a first MOSFET having at least a gate terminal, a source terminal, and a drain terminal;

a first resistive element having a first terminal coupled to the first MOSFET source terminal and a second terminal electrically coupled to the first MOSFET drain terminal;

a second MOSFET having at least a gate terminal, a source terminal, and a drain terminal;

a second resistor having a first terminal coupled to the second MOSFET source terminal;

a diode electrically coupled in series between the first MOSFET drain terminal and the second MOSFET source terminal; and

a comparator circuit having at least a first input terminal coupled to a reference voltage, a second input terminal coupled to receive a voltage signal representative of a current flowing through the solenoid, and a third input terminal coupled to receive the command signal, the comparator operable to supply a switch control signal based on the signals on the first, second, and third input terminals;

a solenoid current monitoring circuit electrically coupled to receive a signal representative of a magnitude of current flowing through the solenoid and operable, in response thereto, to supply the voltage signal representative of the current flowing through the solenoid; and

a driver circuit having at least a first input coupled to receive a command signal and a second input coupled to receive the switch control signal, the driver circuit operable to selectively supply a first gate signal to the first MOSFET gate terminal in response to the command signal and to selectively supply a gate signal to the second MOSFET gate terminal in response to the switch control signal.