Method, System, And Software For A Vehicle Power System

Abstract

Vehicle power distribution circuit for connecting between a battery and a power line connected to a generator or DC/DC-Converter. The circuit has a charging line connecting the battery to the power line for charging the battery when a forward voltage is applied by the generator or DC/DC-Converter. An ideal diode arrangement is provided in the charging line for conducting a forward current from the generator or DC/DC-Converter to the battery when the forward voltage is applied. The ideal diode arrangement prevents conduction of a reverse current from the battery to the power line when a reverse voltage is applied.

Claims

1. A vehicle power distribution circuit comprising: a charging line connecting a battery to a power line for charging the battery when a forward voltage is applied by a generator or direct current (DC)/DC-Converter connected to the power line; and an ideal diode arrangement provided in the charging line for conducting a forward current from the generator or DC/DC-Converter to the battery when the forward voltage is applied and for preventing conduction of a reverse current from the battery to the power line when a reverse voltage is applied.

2. A vehicle power distribution circuit according to claim 1, wherein the ideal diode arrangement comprises: a metal-oxide-semiconductor field-effect transistor (MOSFET) connected in the charging line; and a controller for driving the MOSFET for emulating an ideal diode.

3. A vehicle power distribution circuit according to claim 2, wherein: the MOSFET comprises a body and a gate; and the gate is driven by the ideal diode controller and the body prevents the reverse current when the MOSFET is turned off by the gate.

4. A vehicle power distribution circuit according to claim 3, wherein: the controller comprises a comparator for comparing the voltage across the MOSFET; and the controller drives the gate to turn off the MOSFET when the comparator detects a reverse voltage across the MOSFET.

5. A vehicle power distribution circuit according to claim 1, further comprising a bypass circuit for bypassing the ideal diode arrangement, wherein the bypass circuit comprises a current regulator for regulating a reverse current through the bypass circuit from the battery to the power line.

6. A vehicle power distribution circuit according to claim 5, wherein the bypass circuit further comprises a switch for selectively establishing a bypass current path from the battery to the power line.

7. A vehicle power distribution circuit according to claim 6, wherein the bypass current path is established for enabling non-critical power modules to draw power from the battery.

8. A vehicle power system, comprising: a battery; a generator or direct current (DC)/DC-Converter; a power line for connecting the generator or DC/DC-Converter to one or more powered modules; and a distribution circuit, the distribution circuit comprising: a charging line connected between the battery and the power line for charging the battery when a forward voltage is applied by the generator or DC/DC-Converter; and an ideal diode arrangement provided in the charging line for conducting a forward current from the generator or DC/DC-Converter to the battery when the forward voltage is applied and for preventing conduction of a reverse current from the battery to the power line when a reverse voltage is applied.

9. A vehicle power system according to claim 8, further comprising: a battery line for connecting the battery to one or more critical powered modules.

10. A vehicle power system according to claim 8, wherein the ideal diode arrangement comprises: a metal-oxide-semiconductor field-effect transistor (MOSFET) connected in the charging line; and a controller for driving the MOSFET for emulating an ideal diode.

11. A vehicle power system according to claim 10, wherein: the MOSFET comprises a body and a gate; the gate is driven by the ideal diode controller; and the body prevents the reverse current when the MOSFET is turned off by the gate.

12. A vehicle power system according to claim 11, wherein: the controller comprises a comparator for comparing the voltage across the MOSFET; and the controller drives the gate to turn off the MOSFET when the comparator detects a reverse voltage across the MOSFET.

13. A vehicle power system according to claim 8, further comprising a bypass circuit for bypassing the ideal diode arrangement, wherein the bypass circuit comprises a current regulator for regulating the reverse current through the bypass circuit from the battery to the power line.

14. A vehicle power system according to claim 13, wherein the bypass circuit further comprises a switch for selectively establishing a bypass current path from the battery to the power line.

15. A vehicle power system according to claim 14, wherein the bypass current path is established for enabling non-critical power modules to draw power from the battery.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Illustrative embodiments will now be described with reference to the accompanying drawings in which:

[0026] FIG. 1 shows a schematic illustration of a conventional power distribution architecture in a vehicle;

[0027] FIG. 2 shows a schematic illustration of a power distribution circuit according to a first embodiment; and

[0028] FIG. 3 shows a schematic illustration of a power distribution circuit according to a second embodiment.

DETAILED DESCRIPTION

[0029] FIG. 2 shows a vehicle power distribution circuit 1 according to a first embodiment. The power distribution circuit 1 connects between the vehicle's battery 2 and the generator 6 via a power line 8. Within the vehicles overall power system, the power line 8 may be connected to one or more powered modules (not shown in FIG. 2), similar to the arrangement shown in FIG. 1. Equally, the battery 2 is connected to the vehicle power distribution circuit 1 via battery power line 3, which itself may also be connected to one or more powered modules (not shown in FIG. 2).

[0030] A charging line 7 within the power distribution circuit 1 connects between the battery 2 and the generator or DC/DC-Converter 6 via their respective battery and power lines 3, 8. An ideal diode arrangement 11 is provided in the charging line 7 and is arranged for conducting a forward current from the generator or DC/DC-Converter 6 to the battery 2 arrangement for charging the battery 2. Conversely, the ideal diode arrangement 11 prevents the conducting of a reverse current from the battery 2 to the power line 8 when a reverse voltage is applied.

[0031] As is known in the art, a perfect or ideal diode is not a diode in the conventional sense, but is an arrangement of a MOSFET and an ideal diode controller that emulates the behaviour of an ideal diode. Consequently, the arrangement provides very low forward voltage drop and negligible reverse current when a reverse voltage is applied. Within the arrangement, the source and gate of the MOSFET are connected in the charging line 7 such that the MOSFET body blocks the reverse current when the MOSFET is turned off. Conversely, when the MOSFET is on, the forward voltage drops and power dissipation is minimal The switching of the MOSFET is controlled by the driving of the MOSFET's gate by the ideal diode controller, which senses a reverse current through the MOSFET, and drives the gate to turn it off, thereby blocking the reverse current.

[0032] In this embodiment, the MOSFET is an N-channel MOSFET, although other MOSFET configurations are possible. The ideal diode controller has an internal charge pump for driving the MOSFET gate higher than its anode, a forward comparator for turning on the MOSFET, and a reverse current comparator for turning off the MOSFET when a reverse current is detected. The reverse comparator monitors the voltage across controller's anode and cathode and, if a reverse current is detected, the MOSFET's gate is shorted with a strong pulldown current. This rapidly provides a strong gate drive to pull down the gate to the source voltage, thereby turning off the MOSFET rapidly. As such, the ideal diode arrangement 11 may provide a rapid response to prevent the conduction of a reverse current through the MOSFET and hence the charging line 7. Furthermore, advantageously, by using a comparator, the shutdown current threshold may be set extremely low, thereby allowing the emulation of an ideal diode response.

[0033] In use, the vehicle power distribution circuit 1 provides a forward current path for allowing the generator or DC/DC-Converter 6 to charge the battery 2 (shown right to left in FIG. 2). As this forward current is conducted through the MOSFET, the forward voltage drop is minimal. Accordingly, this avoids the need for a heat sink that might otherwise be required to manage the waste heat arising from forward conduction power losses, thereby providing both cost and space savings.

[0034] The components of the generator or DC/DC-Converter 6 are internally protected from short circuits. However, in the event of a short circuit 9 on the power line 8 or within the generator or DC/DC-Converter 6 itself, the voltage in the power line 8 drops lower than the battery 2, thereby applying a reverse voltage across the ideal diode arrangement 11. However, the onset of the current reversal causes the ideal diode arrangement 11 to rapidly turn off the MOSFET thereby preventing a reverse current (shown left to right in FIG. 2) being conducted through the charging line 7. This thereby prevents the battery line 3 from being drawn low, and hence protects the battery 2 and the associated powered modules 4 from the short circuit 9. Once the short circuit 9 is removed, the forward current through the power distribution circuit is re-established.

[0035] FIG. 3 shows a vehicle power distribution circuit 1 according to a second embodiment. This embodiment is substantially the same as the first embodiment, except that a bypass circuit 12 is provided for bypassing the ideal diode arrangement 11. The bypass circuit 12 includes a current regulator 13 for regulating a reverse current through the bypass circuit 12. The current regulator 13 includes a switch which when closed establishes the bypass reverse current path from the battery 2 to the power line 8. With this arrangement, a regulated reverse current may be provided from the battery if needed. For instance, the bypass current path may be established for allowing non-critical powered modules to draw power from the battery in situations where the generator or DC/DC-Converter 6 is not actively generating DC power. Nevertheless, in normal operations, the bypass circuit can be disconnected, allowing the ideal diode arrangement 11 to provide short circuit protection in the same way as described in relation to FIG. 2.

[0036] Accordingly, with the above described arrangements a vehicle power distribution circuit and power architecture system may be provided which allows for robust and rapid short circuit protection, without significant power losses. Importantly, by utilising the characteristics of a perfect or ideal diode arrangement, the current at the moment when the short protection activates, is zero or substantially so. As a consequence, energy isn't lost during switching of the MOSFET, which could otherwise cause heating of the circuit.

[0037] It will be understood that the embodiments illustrated above shows an application only for the purposes of illustration. In practice, embodiments may be applied to many different configurations, the detailed embodiments being straightforward for those skilled in the art to implement.

[0038] For example, although the arrangement allows for short circuit protection without the need for complex microprocessors, it will be understood that implementations may be used in conjunction with one or more microprocessors, for instance to provide performance feedback and fault monitoring.

[0039] Moreover, although a vehicle power distribution circuit has been described in the illustrative embodiments, it will be understood that the circuit may be incorporated into a distribution box or form part of a power distribution system incorporated into a vehicle.