Circuit and method for controlling current flow through a solenoid
AssigneeHoneywell International Inc.
InventorTerry J. Ahrendt
Life of this patent
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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.
Claims30
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.
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.
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 and operable, 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.
In a circuit including series connected first controllable switch and a diode that are electrically coupled in parallel with a solenoid, and a series-connected second controllable switch and first resistor that are electrically coupled in series with the solenoid, a method of controlling current flow through the solenoid, comprising:
- closing the first and second controllable switches, whereby a current flows from a first voltage potential through the solenoid, the second controllable switch, and the first resistor;
- determining when the current flow through the solenoid reaches a first predetermined current magnitude;
- and
- opening the second controllable switch when the first predetermined current magnitude is reached, whereby the current flows through the solenoid, the diode, and the first controllable switch.
Dependencies are inferred from the claim text.