Voltage and current regulator with automatic switchover

Abstract

A system for energizing an inductive load includes a voltage regulator for providing a constant voltage across the load until the current builds up to a particular value, and a current regulator which then takes over to provide a constant holding current at a lower value. The voltage regulator may include a closed loop for holding the voltage across the inductive load constant or may respond to a regulated voltage value to control a power stage for providing a constant voltage. The voltage across a sensing resistor in the power stage controls the crossover from the voltage regulation mode, to the current regulation mode and the current regulator automatically resets the reference to control the power stage to provide a constant current of a lower value through the load. The system can be used to supply current to coils of injector valves in a fuel injection system, and may include two power stages for supplying current to two banks of coils. The regulator system is switched from one power stage to the other during successive 180° rotary positions of the engine for both stages.

We claim: .[.1. A circuit for supplying current from a power supply to an inductive load, including in combination: 
     
        stage to apply increased current to the load..]. 10. A circuit for .[.supply.]. .Iadd.supplying .Iaddend.current from a power supply to first and second banks of coils of injector valves, including in combination: power stage means including first and second sections coupled to the power supply and each having an input terminal and an output terminal adapted to be connected to one bank of coils to supply current thereto, said power stage means having output current sensing means common to said first and second sections;   voltage regulator means adapted to provide a substantially constant voltage;   current regulator means having an input and an output, means coupling said input of said current regulator means to said output current sensing means; and   circuit means including first and second sections each coupled to said input terminal of one of said sections of said power stage means, said circuit means being coupled to said voltage regulator means and responsive to the voltage provided thereby to provide a substantially constant voltage at said output terminals of said sections of said power stage means, said circuit means being coupled to said output of said current regulator means and controlling said sections of said power stage means so that the current supplied thereby to the bank of coils connected thereto is maintained substantially constant;   said current regulator means being rendered operative to control said sections of said power stage means in response to a voltage across said output current sensing means which indicates that the current in the coils   
     
     
        has reached a predetermined value. 11. A circuit in accordance with claim 10 further including switch means coupled to said circuit means for selectively rendering said first and second sections thereof operative to 
     
     
        control said sections of said power stage means coupled thereto. 12. A circuit in accordance with claim 11 wherein said switch means includes means for actuating the operative sections of said circuit means to control the section of said power stage means connected thereto to initiate the supply of current to the associated bank of coils and to 
     
     
        terminate such current supply. 13. A circuit in accordance with claim 10 wherein said current regulator means includes, a differential amplifier having first and second inputs and an output, with said first input of said differential amplifier forming said input of said current regulator means and said output of said differential amplifier forming said output of said current regulator means,   reference voltage means connected to said second input of said differential amplifier,   said differential amplifier being rendered operative when the voltage applied to said first input thereof from said output current sensing means has a value equal to the voltage applied to said second input of said differential amplifier to control said circuit means and cause said sections of said power stage means to supply substantially constant   
     
     
        current to the associated bank of coils. 14. A circuit in accordance with claim 13 wherein said reference voltage means is coupled to said output of said differential amplifier and includes means for changing the voltage applied to said second input of said differential amplifier so that said current regulator means controls said power stage means so that the current supplied to the coils is maintained at a substantially constant value below said predetermined value. .[.15. A circuit in accordance with claim 10 wherein each of said sections of said circuit means includes first, second and third transistors, with said first transistor having base, emitter and first and second collector electrodes, and said second and third transistors each having base, emitter and collector electrodes, means connecting the path between said emitter and said first collector of said first transistor in series with the path between said emitter and said collector of said second transistor across the power supply, and connecting the junction between said first collector and said emitter of said second transistor to said input of the section of said power stage means connected to such section of said circuit means, resistor means connected in series with the path between said emitter and said collector of said third transistor across the power supply, the junction between said resistor and said emitter of said third transistor being connected to said base of said first transistor, and means connecting said second collector of said first transistor to said base of said third transistor and for controlling the current therein so that the conductivity of said first transistor is controlled to thereby control the current applied to said input of said connected section of said power stage means..]. .Iadd. 16. An integrated circuit for controlling the supply of current from a power supply to a load, the integrated circuit being adapted to control a power stage, the power stage having a power input terminal for being coupled to the power supply, a control terminal and an output terminal, the output terminal of the power stage being adapted to be connected to the load to supply current thereto, the integrated circuit including in combination: first and second power supply conductors;   voltage regulator means for controlling the power stage to maintain a substantially constant voltage at the output terminal thereof during a voltage regulation operating mode;   first circuit means for coupling said voltage regulator means to said power stage control terminal, said first circuit means being directly connected between said power stage control terminal and said second power supply conductor;   means adapted to supply a signal representative of the magnitude of the load current;   current regulator means having input, output and control terminals, said control terminal of said current regulator means being connected to said means for applying said signal representative of the magnitude of the load current;   second circuit means coupling said output terminal of said current regulator means to said power stage control terminal for controlling the current supplied by the power stage to the load, said second circuit means being directly connected between said power stage control terminal and said second power supply conductor so that said second circuit means includes a current path in parallel with said first circuit means; and   current source means coupled to said power stage control terminal for energizing said first and second circuit means to enable regulation of the load current and voltage. .Iaddend..Iadd. 17. The integrated circuit of claim 16 wherein said first circuit means includes an emitter follower transistor having a collector electrode directly connected to said second power supply conductor, a base electrode coupled to said output terminal of said voltage regulator means, and an emitter electrode coupled to said power stage control terminal. .Iaddend..Iadd. 18. The integrated circuit of claim 16 wherein said current regulator means includes a differential amplifier utilizing two Darlington connected pairs of transistors of the same conductivity type having collector electrodes coupled to said first power supply conductor and emitter electrodes coupled to said second power supply conductor. .Iaddend..Iadd. 19. The integrated circuit of claim 18 wherein:   said first power supply conductor is adapted to receive a first potential;   said second power supply conductor is adapted to receive a potential which is negative with respect to said first potential; and   said Darlington connected pairs of transistors are of the NPN conductivity type. .Iaddend..Iadd. 20. The integrated circuit of claim 18 further including a further current source having a transistor of another conductivity type connected between the collector electrodes of one of said transistors of each of said Darlington connected pairs of transistors. .Iaddend. .Iadd. 21. The integrated circuit of claim 16 wherein said second circuit means includes an additional current source. .Iaddend..Iadd. 22. The integrated circuit of claim 21 wherein said additional current source includes input, output and control terminals, said additional current source being responsive to control signals at said control terminal thereof to control the magnitude of the output current thereof. .Iaddend..Iadd. 23. The integrated circuit of claim 22 wherein said additional current source includes in combination:   first transistor means having an emitter electrode for providing said input terminal, a base electrode, a first collector electrode, and a second collector electrode for providing said output terminal; and   second transistor means having an emitter electrode connected to said base electrode of said first transistor means, and a base electrode connected to said first collector electrode of said first transistor means for providing said control terminal of said current source. .Iaddend. .Iadd. 24. A circuit for controlling the energy flowing through first and second power stages for respectively driving first and second electrical loads which are to be energized during different time intervals, each of the power stages having a control terminal, the circuit including in combination:   first differentially connected transistor and second differentially connected transistor having emitter electrodes connected together, base electrodes, and collector electrodes;   first circuit means for coupling said collector electrode of said first differentially connected transistor to the control terminal of the first power stage;   second circuit means for coupling said collector electrode of said second differentially connected transistor to the control terminal of the second power stage;   controllable constant current source means connected to said emitter electrodes of said first and second differentially connected transistors, said controllable constant current source means selectively determining whether both of said differentially connected transistors can be rendered conductive by control signals applied to said base electrodes thereof   said first circuit means including a first controllable variable current supply means having a control terminal connected to said collector electrode of said first differentially connected transistor and an output electrode connected to said control terminal of the first power stage;   said second circuit means including a second controllable variable current supply means having a control terminal connected to said collector electrode of said second differentially connected transistor and an output electrode connected to said control terminal of the second power stage; and   said first controllable variable current supply means being responsive to said first differentially connected transistor being rendered conductive to cause the first power stage to energize the first load and said second controllable variable current supply means being responsive to said second differentially connected transistor being rendered conductive to cause the   
     
     
        second power stage to energize the second load. .Iaddend. .Iadd. 25.  The circuit of claim 24 further including in combination: current regulator means having an output electrode connected to said control terminal of said first controllable variable current supply means and to said control terminal of said second variable controllable current supply means, said current regulator means being operative to enable whichever of said first and second variable controllable current supply means is operative to provide control signals which cause the power stage connected thereto to provide regulated currents to an electrical load. .Iaddend..Iadd. 26. The circuit of claim 24 further including in combination:   voltage regulating means having an output terminal, means coupling said output terminal of said voltage regulating means to the control terminals of the first and second power stages, said voltage regulating means being responsive to the output current of whichever of said first and second controllable variable current supply means is operative to enable the corresponding power stage to develop a regulated voltage across the electrical load associated therewith during a voltage regulation mode of operation. .Iaddend..Iadd. 27. The circuit of claim 26 wherein said means coupling the output terminal of the voltage regulating means to the control terminals of the power stages includes an emitter follower transistor having a base electrode connected to said output terminal of said voltage regulator means, a collector electrode connected to receive a reference potential, and an emitter electrode connected to the control terminals of the first and second power stages. .Iaddend. .Iadd. 28. A circuit for controlling the energy flowing through first and second power stages for respectively driving first and second electrical loads which are to be energized during different time intervals, each of the power stages having a control terminal, the circuit including in combination:   first differentially connected transistor and second differentially connected transistor having emitter electrodes connected together, base electrodes, and collector electrodes;   first circuit means coupling said collector electrode of said first differentially connected transistor to the control terminal of the first power stage, said first circuit means including a first controllable variable current supply means having a control terminal connected to said collector electrode of said first differentially connected transistor and an output electrode connected to said control terminal of the first power stage, said first controllable variable current supply means being responsive to said first differentially connected transistor being rendered conductive to cause the first power stage to energize the first load;   second circuit means for coupling said collector electrode of said second differentially connected transistor to the control terminal of the second power stage, said second circuit means including a second controllable variable current supply means having a control terminal connected to said collector electrode of said second differentially connected transistor and an output electrode connected to said control terminal of the second power stage, said second controllable variable current supply means being responsive to said second differentially connected transistor being rendered conductive to cause the second power stage to energize the second load;   each of said controllable variable current supply means including in combination first transistor means having an emitter electrode, a base electrode, a first collector electrode, and a second collector electrode for providing said output terminal; and second transistor means having an emitter electrode connected to said base electrode of said first transistor means, and a base electrode connected to said first collector electrode of said first transistor means for providing said control terminal of said controllable variable current supply means; and   controllable constant current source means connected to said emitter electrodes of said first and second differentially connected transistors, said controllable constant current source means determining whether both of said differentially connected transistors can be rendered conductive by control signals applied to said base electrode thereof. .Iaddend. .Iadd. 29. A circuit for supplying current from a power supply to first and second banks of coils of injector valves, including in combination:   power stage means including first and second sections coupled to the power supply and each having an input terminal and an output terminal adapted to be connected to one bank of coils to supply current thereto, said power stage means having output current sensing means common to said first and second sections;   voltage regulator means adapted to provide a substantially constant voltage;   current regulator means having an input and an output, means coupling said input of said current regulator means to said output current sensing means; and   circuit means including first and second sections each coupled to said input terminal of one of said sections of said power stage means, said circuit means being coupled to said voltage regulator means and responsive to the voltage provided thereby to provide a substantially constant voltage at said output terminals of said sections of said power stage means, said circuit means being coupled to said output of said current regulator means and controlling said sections of said power stage means so that the current supplied thereby to the bank of coils connected thereto is maintained substantially constant;   current source means coupled to said power stage means for energizing said circuit means to enable regulation of the current and voltage of said first and second banks of coils of injector valves; and   said current regulator means being rendered operative to control said sections of said power stage means in response to a voltage across said output current sensing means which indicates that the current in the coils   
     
     
        has reached a predetermined value. .Iaddend. .Iadd. 30.  A circuit for supplying current from a power supply to an inductive load, including in combination: power stage means coupled to the power supply and having an input terminal and an output terminal adapted to be connected to the inductive load to supply current thereto, said power stage means having output current sensing means:   voltage regulator means coupled to said input terminal for controlling said power stage means to maintain a substantially constant voltage at said output terminal thereof;   current regulator means including a current regulator circuit having an input and an output, means coupling said input of said current regulator circuit to said output current sensing means;   circuit means coupling said output of said current regulator circuit to said input terminal of said power stage means for controlling the current supplied by said power stage to the inductive load, said current regulator circuit being rendered operative to control the output current in response to a voltage across said output current sensing means which indicates that the current in the load has reached a predetermined value;   said current regulator circuit further including a differential amplifier having first and second inputs and an output, said first input of said differential amplifier forming said input of said current regulator circuit and said output of said differential amplifier forming said output of said current regulator circuit;   reference voltage means connected to said second input of said differential amplifier, said reference voltage means including means having first and second branches with substantially fixed current therein, and means for providing a reference voltage which is related to the value of the currents in said first and second branches, said reference voltage means further including means for shunting said first branch so that the reference voltage is related to the value of the current in said second branch alone; and   means coupling said circuit means to said reference voltage means for changing and reference voltage applied to said second input of said differential amplifier in response to a signal in said circuit means produced in response to the voltage across said output current sensing means, to control said power stage to reduce said output current to a value less than said predetermined value. .Iaddend..Iadd. 31. A circuit for supplying current for a power supply to both of first and second banks of coils of injector valves, including in combination:   power stage means including first and second sections coupled to the power supply and each having an input terminal and an output terminal adapted to be connected to one bank of coils to supply current thereto, said power stage means having output current sensing means common to said first and second sections;   voltage regulator means adapted to provide a substantially constant voltage;   current regulator means having an input and an output, means coupling said input of said current regulator means to said output current sensing means; and   circuit means including first and second sections each coupled to said input terminal of one of said sections of said power stage means, said circuit means being coupled to said voltage regulator means and responsive to the voltage provided thereby to provide a substantially constant voltage at said output terminals of said sections of said power stage means, said circuit means being coupled to said output of said current regulator means and controlling said sections of said power stage means so that the current supplied thereby to the bank of coils connected thereto is maintained substantially constant, each of said sections of said circuit means including first, second and third transistors, with said first transistors having base, emitter and first and second collector electrodes, and said second and third transistors each having base, emitter and collector electrodes, means connecting the path between said emitter and said first collector of said first transistor in series with the path between said emitter and said collector of said second transistor across the power supply, and connecting the junction between said first collector and said emitter of said second transistor to said input of the section of said power stage means connected to such section of said circuit means, resistor means connected in series with the path between said emitter and said collector of said third transistor across the power supply, the junction between said resistor and said emitter of said third transistor being connected to said base of said first transistor, and means connecting said second collector of said first transistor to said base of said third transistor and for controlling the current therein so that the conductivity of said first transistor is controlled to thereby control the current applied to said input of said connected section of said power stage means; and   said current regulator means being rendered operative to control said sections of said power stage means in response to a voltage across said output current sensing means which indicates that the current in the coils has reached a predetermined value. .Iaddend.