Apparatus for bi-directional power switching in low voltage vehicle power distribution systems

• US 20120319483A1
• Filed: 06/20/2011
• Published: 12/20/2012
• Est. Priority Date: 06/20/2011
• Status: Active Grant

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Scruggs, Michael K., Sozusen, Serdar T.
• Granted Patent: US 8,941,264 B2
• Time in Patent Office: Days
• US Class Current: 307/52
• CPC Class Codes: B60R 16/033 characterised by the use of electrical cells or batteries for propulsion puposes B60K1/04; supplying batteries to, or removing batteries from, vehicles B60S5/06; testing of charge state G01R31/36
• CPC Class Codes: H02J 1/082 Plural DC voltage, e.g. DC supply voltage with at least two different DC voltage levels
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources
• CPC Class Codes: H02J 1/108 using diodes blocking reverse current flow H02J1/12 takes precedence
• CPC Class Codes: H02J 2310/46 for ICE-powered road vehicles
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence
• CPC Class Codes: H02J 9/06 with automatic change-over , e.g. UPS systems

Abstract

A plurality of modules each including at least a pair of series connected power MOSFETs are configured between a plurality of DC voltage sources, and a plurality output terminals for connection to respective loads, are controlled for selectively applying power to the loads via time delay switching incorporating forward biased intrinsic diodes of the MOSFETs in a given current path during initial application of power to a load, whereby a predetermined period of time after turning on one of the series connected MOSFETs, the associated other MOSFET is turned on to shunt its intrinsic diode for reducing the resistance in the current path to maximize current flow. The configuration of the plurality of power MOSFETs is also controlled for selectively providing bi-directional current flow between said plurality of DC voltage sources.

Claims

1. In a low voltage high current DC power distribution system, the method comprising the steps of:

connecting an output of a primary battery to a drain electrode of a first power MOSFET switch;

connecting a source electrode of said first power MOSFET switch to a source electrode of a second power MOSFET switch;

connecting a drain electrode of said second power MOSFET switch to an output of a secondary battery;

comparing the voltage level of said primary battery to that of said secondary battery; and

operating a controller in a first mode to sense when the voltage level of the primary battery is greater than that of the secondary battery, for applying a control signal to a gate electrode of said first power MOSFET switch for turning it on to connect said primary battery through the relatively high resistance of a body diode of said second power MOSFET switch to said secondary battery, and after a predetermined period of time applying a control signal to a gate electrode of said second power MOSFET switch to turn it on to shunt its body diode with its relatively low resistance channel, for substantially reducing the resistance in the current path between said primary and secondary batteries.

2. The method of claim 1, further including the step of:

operating said controller in a second mode to sense when the voltage level of the secondary battery is greater than that of said secondary battery, for applying a control signal to a gate electrode of said second power MOSFET switch for turning it on to connect said secondary battery through the relatively high resistance of a body diode of said first power MOSFET switch to said primary battery, and after a predetermined period of time applying a control signal to a gate electrode of said first power MOSFET switch to turn it on to shunt its body diode with its relatively low resistance channel, for substantially reducing the resistance in the current path between said primary and secondary batteries.

3. The method of claim 2, further including the step of:

operating said controller in a third mode to sense when the voltage levels of the primary and secondary batteries are equal, for simultaneously applying control signals to the gate electrodes of said first and second power MOSFET switches for turning them on to establish a relatively low resistance current path between said primary and secondary batteries.

4. In a low voltage high current DC power distribution system, the method comprising the steps of:

(A) connecting a DC voltage supply to a source electrode of a first power MOSFET switch;

(B) coupling a drain electrode of said first power MOSFET switch to an output terminal for delivering power to a load;

(C) operating a controller for initially keeping said first power MOSFET switch turned off, whereby a relatively high resistance current path is established from a source of said DC voltage, through a forward biased body diode of said first power MOSFET switch to said load; and

(D) operating said controller after a predetermined period of time from applying power to said load, for applying a control signal to a gate electrode of said first power MOSFET switch for turning it on to establish a relatively low resistance current path from said source of DC voltage to said load.

5. The method of claim 4, further including the steps of:

(E) connecting the drain electrode of said first power MOSFET switch directly to a drain electrode of a second power MOSFET switch;

(F) connecting a source electrode of said second power MOSFET switch to said output terminal; and

(G) operating said controller, prior to initiating step (C), to apply a control signal to a gate electrode of said second power MOSFET switch for turning it on to establish a relatively low resistance current path from the drain electrode of said first power MOSFET switch to said output terminal, following by initiating step (C).

6. A low voltage high current DC power distribution system comprising:

at least a first DC voltage source;

at least a first power MOSFET switch including a first intrinsic diode, a gate electrode, a source electrode connected said first DC voltage source, and a drain electrode, said first intrinsic diode having an anode and cathode connected between the source and drain electrodes, respectively;

a first output terminal for connection to a first load;

an internal bus coupled to the drain of said first power MOSFET;

at least a second power MOSFET switch having a gate electrode, a drain electrode connected to said internal bus, and a source electrode connected to said first output terminal; and

controller means for first applying a control signal to the gate of said second power MOSFET to turn it on for connecting said bus to said output terminal via a relatively low resistance current path between the former'"'"'s drain and source electrodes, whereby a relatively high resistance current path is provided from said first DC voltage source, through said first intrinsic diode to the drain electrode of said second power MOSFET, to limit the initial magnitude of current flowing from said first DC voltage source to a load; and

said controller means including means for applying a control signal to the gate electrode of said first power MOSFET a predetermined time after turn on of said second power MOSFET, for turning on said first power MOSFET switch to substantially reduce the resistance between its source and drain electrodes, thereby substantially reducing the relative resistance in the current path between said first DC voltage source and said first output terminal.

7. The system of claim 6, further including:

a third power MOSFET switch connected in parallel with said first power MOSFET switch, whereby an intrinsic diode of said third power MOSFET in parallel with the intrinsic diode of said first power MOSFET switch reduces the initial resistance in that portion of the current path in half;

said controller means being operable for simultaneously applying control signals to gate electrodes of said first and third power MOSFET switches to turn on a predetermined time after time on of said second power MOSFET switch, thereby reducing by one-half the resistance of the portion of the current path between source and drain electrodes of said first and third MOSFET switches relative to the first MOSFET switch alone, and providing for the first and third MOSFET switches to each share about one-half of the magnitude of current flowing from said first DC voltage source to said first output terminal at any time.

8. The system of claim 7, further including:

a second DC voltage source;

a fourth power MOSFET switch having a gate electrode, a source electrode connected to said second DC voltage source, a drain electrode coupled to said internal bus, and an intrinsic diode having an anode electrode connected to said drain electrode;

said controller means further including means for initially establishing a relatively high resistance current flow path from said second DC voltage source to a load coupled to said internal bus, and after a predetermined time delay applying a control signal to the gate of said fourth power MOSFET switch for turning it on to substantially reduce the resistance in the current flow path between said second DC voltage source and a load.

9. The system of claim 8, further including:

a fifth power MOSFET switch having a gate electrode, and source and drain electrodes connected to the source and drain electrodes, respectively, of said fourth power MOSFET switch, thereby connecting said fourth and fifth power MOSFET switches in parallel for at any time sharing current flow through that portion of the current path they mutually represent; and

said controller means being operative for simultaneously turning on or off said fourth and fifth power MOSFETs.

10. The system of claim 9, further including:

a third DC voltage source; and

a sixth power MOSFET switch having a source electrode connected to said third DC voltage source, a gate electrode for receiving a control signal, a drain electrode coupled to said internal bus, and an intrinsic diode having anode and cathode electrodes formed between its source and drain electrodes, respectively;

said controller means being operable a predetermined time after current flows from said third DC voltage through the relatively high resistance forward biased intrinsic diode of said sixth power MOSFET to a load coupled to said internal bus, for applying a control signal to the gate of said sixth power MOSFET to turn it on for substantially reducing the relative resistance between its source and drain electrodes.

11. The system of claim 10, further including:

a seventh power MOSFET switch connected in parallel with said sixth MOSFET switch with source and drain electrodes, respectively, connected in common, and having a gate electrode; and

said controller means being operable for simultaneously turning on and off said sixth and seventh power MOSFETs.

12. The system of claim 10, further including:

eight and ninth power MOSFET switches having source electrodes connected together, and independent gate electrodes, said eighth MOSFET switch having a drain electrode connected in common to the source electrode of said first power MOSFET switch and to said first DC voltage source;

said first DC voltage source being a primary battery;

said third DC voltage source being a DC generator; and

said controller means being operable for applying control signals to the gate electrodes of said eighth and ninth power MOSFET switches to turn them on for connecting said generator to said first DC voltage source to charge it.

13. The system of claim 12, further including:

tenth and eleventh power MOSFET switches having source electrodes connected together, and independent gate electrodes, said tenth power MOSFET having a drain electrode connected in common to the source electrode of said seventh MOSFET switch and said third DC voltage source, said eleventh power MOSFET switch having a drain electrode connected in common to the source electrode of said fifth power MOSFET switch and said second DC voltage source serving as a secondary battery; and

said controller being operable to apply control signals to the gate electrodes of said tenth and eleventh power MOSFET switches to turn them on to connect said DC generator to said second DC voltage source to charge it.

14. The system of claim 13, further including:

twelfth and thirteenth power MOSFET witches each having source electrodes connected in common, each having a gate electrode, said eleventh power MOSFET switch having a drain electrode connected to said primary battery, said thirteenth power MOSFET having a drain electrode connected to said secondary battery;

said controller means being operable in one mode in response to said primary battery voltage level being greater then said secondary battery voltage level, for applying a control signal to the gate of said twelfth power MOSFET switch for turning it on to initially establish a current path from said primary battery, through the relatively low resistance drain to source current path of said eleventh power MOSFET switch, the relatively high resistance forward biased intrinsic diode of said twelfth power MOSFET switch, to said secondary battery, and a predetermined time after turning on said twelfth power MOSFET switch, apply a control signal to the gate of said thirteenth power MOSFET to turn it on for substantially reducing the resistance between its source and drain electrodes; and

said controller being operable in a second mode in response to said secondary battery voltage level being greater than primary voltage level, for applying a control signal to the gate of said thirteenth power MOSFET to turn it on to initially establish a current path from said secondary battery, through the relatively low resistance drain to source current path of said twelfth power MOSFET, the relatively high resistance forward biased intrinsic diode of said eleventh power MOSFET switch to said primary battery, and a predetermined time after turning on said thirteenth power MOSFET switch, apply a control signal to the gate of said twelfth power MOSFET to turn it on for substantially reducing the resistance between its source and drain electrodes.

15. The system of claim 14, further including:

fourteenth, fifteenth, and sixteenth power MOSFET switches each having a source electrode connected to said internal bus, each having an independent gate electrode, said fourteenth power MOSFET switch further having a drain electrode connected in common to the drain electrodes of said first and third power MOSFET switches, said fifteenth power MOSFET switch further having a drain electrode connected in common to the drain electrodes of said sixth an seventh power MOSFET switches, and said sixteenth power MOSFET switch having a drain electrode connected in common to the drain electrodes of said fourth and fifth power MOSFET switches; and

said controller means being operable for upon start up of said system applying control signals to the gate electrodes of said fourteenth, fifteenth, and sixteenth power MOSFET switches for turning them on, and for turning any one or more of these switches off in the event of an associated overload condition.

16. The system of claim 15, further including:

said second power MOSFET switch having its drain electrode directly connected to the source electrode of said fourteenth power MOSFET switch;

second and third output terminals for connection to second and third loads, respectively;

a seventeenth power MOSFET switch having a drain electrode directly connected to the source electrode of said sixteenth power MOSFET switch, a gate electrode for receiving a control signal, and a source electrode connected to said second output terminal; and

an eighteenth power MOSFET switch having a drain electrode directly connected to the source electrode of said sixteenth power MOSFET switch;

said controller being selectively operable to apply control signals to the gates of said second, seventeenth, and eighteenth power MOSFET switches for selectively connecting said first through third output terminals to said internal bus.

17. The system of claim 6, wherein said controller includes a Field-Programmable Gate Array (FPGA).

18. The system of claim 17, wherein said controller includes logic means for sensing and comparing the voltage levels of said first and second DC voltage sources.

19. The system of claim 16, wherein said first through eighteenth power MOSFET switches are provided from no greater than nine modules, each module including at least two series connected MOSFETs.

20. The system of claim 10, wherein said third source of DC voltage is a motor driven DC generator.

21. A DC power distribution system, comprising:

first through fourth power MOSFET switches each having source, drain, and gate electrodes, and an intrinsic diode represented by anode and cathode electrodes connected between associated source and drain electrodes, respectively, the drain of said first MOSFET switch being connected to the source of said second power MOSFET, the drain of said third MOSFET being connected to the source of said fourth MOSFET switch, and the source of said first power MOSFET switch being connected to the source of said third power MOSFET switch;

a source of reference potential;

a secondary battery having a positive terminal connected to the common connection between the drain and source electrodes of said first and second power MOSFET switches, respectively, and a negative terminal to said source of reference potential;

a first output terminal for connection to a first load;

means for connecting the drain of said second power MOSFET switch to said first output terminal;

a second output terminal for connection to a second load;

means for connecting the drain of said fourth power MOSFET to said second output terminal;

controller means operable in a first mode when the voltage level of said primary battery is greater than that of said secondary battery for initially applying a control signal to the gate of said third power MOSFET switch to turn it on, for initially connecting the primary battery through a current path including a relatively low resistance channel of said third power MOSFET switch, and the relatively high resistance of the intrinsic diode of said first power MOSFET switch to said secondary battery, and after a predetermined delay period from turning on said third power MOSFET switch, applying a control signal to the gate of said first power MOSFET switch to turn it on to substantially reduce the resistance between its source and drain electrodes for permitting maximum current flow; and

said controller means being operable in a second mode when the voltage level of said secondary battery is greater than that of said primary battery, for initially applying a control signal to the gate of said first power MOSFET switch to turn it on, for initially connecting said secondary battery through a current path including a relatively low resistance channel of said first power MOSFET switch and the relatively high resistance of the intrinsic diode of said third power MOSFET switch to said primary battery, and after a predetermined delay period from turning on said first power MOSFET switch, applying a control signal to the gate of said third power MOSFET switch to turn it on to substantially reduce the resistance between its source and drain electrodes for permitting maximum current flow.