GB2571518A

GB2571518A - An energy storage backup system

Info

Publication number: GB2571518A
Application number: GB1802061.0A
Authority: GB
Inventors: Ash Buckley Peter
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2018-02-08
Filing date: 2018-02-08
Publication date: 2019-09-04
Also published as: GB201802061D0

Abstract

An energy storage backup system 5 for a vehicle comprises a primary energy storage means 30 for supplying energy to one or more primary vehicle loads 10, a secondary energy storage means 40 for supplying energy to one or more secondary vehicle loads 20 and a switch 60 in series between the primary and secondary storage means outputs. If the switch is in a closed position, both the primary storage means and the secondary storage means are connected to both the primary vehicle loads and secondary vehicle loads. If the switch is in an open position, the secondary storage means output is isolated from the primary storage means output, and the secondary storage means supplies energy only to the secondary vehicle loads. The energy storage means may be a secondary battery, super capacitor, ultra-capacitor, or fuel cell device. A DC/DC converter 50 may be provided to convert a high voltage from the secondary battery to 12v, suitable for charging the primary battery. A measurement means S1 may be a voltage or current measurement device or sensor. A control means 80 may be provided to control the switching of the switch dependent upon the value of the measurement means.

Description

TECHNICAL FIELD

The present invention relates to an energy storage backup system. Particularly, but not exclusively, the present invention relates to an energy storage backup system for a vehicle for ensuring continuation of power supply to critical vehicle systems.

Aspects of the invention relate to an energy storage backup system, a method of controlling an energy storage backup system, a control means, and a vehicle.

BACKGROUND

It is known for modern vehicles to have complex electrical systems and many electrical components which consume electrical power. The electrical components consuming electrical power may be called electrical loads. Some electrical loads are deemed as critical to vehicle function and these loads must be supplied at all times requiring power supply backup systems to be installed. Critical vehicle systems may include braking or safety related systems for example.

Typically a vehicle can be fitted with a primary energy storage device and a secondary energy storage device (which may be a fuel cell, battery or capacitor, for example a super capacitor or ultra-capacitor) as a standby just in case the primary energy storage device fails for some reason. However this extra energy storage device can add cost and weight to the electrical system, and may require significant package space.

It is an aim of the present invention to provide an alternative approach to providing an energy storage backup system and/or to overcome the disadvantages associated with the prior art.

SUMMARY OF THE INVENTION

Aspects of the present invention relate to an energy storage backup system, a method of controlling an energy storage backup system, a control means, and a vehicle as claimed in the appended claims.

According to an aspect of the present invention there is provided an energy storage backup system for a vehicle comprising a primary energy storage means for supplying energy to one or more primary vehicle loads, a secondary energy storage means for supplying energy to one or more secondary vehicle loads, a switch in series between the secondary energy storage means output and the primary energy storage means output and a connection between the secondary energy storage means and the switch, connected to the secondary vehicle loads, wherein, if the switch is in a closed position both the primary energy storage means and the secondary energy storage means are connected to both the primary vehicle loads and secondary vehicle loads, and if the switch is in an open position, the secondary energy storage means output is isolated from the primary energy storage means output, and the secondary energy storage means supplies energy only to the secondary vehicle loads.

Advantageously this may provide a reliable power supply to critical systems connected to the secondary energy storage means if a fault occurs in the primary energy storage means which threaten to affect the secondary energy storage means voltage or current supply. Tactically it is therefore a good strategy to connect critical systems required to keep the vehicle moving to the secondary energy storage means.

In an embodiment, an energy storage backup system for a vehicle may comprise a measurement means for measuring a value of a system parameter. The measurement means could be a voltage measurement device or sensor or a current measurement device or sensor. The position of the measurement means helps to determine the location of a potential fault and when the measurement means indicates a fault condition the primary energy storage means and primary vehicle loads can be separated from the secondary energy storage means and secondary vehicle loads.

In an embodiment, an energy storage backup system for a vehicle may comprise control means to control the switching of the switch dependent upon the value of the system parameter measured by the measurement means. The control means can advantageously control the primary energy storage means and primary vehicle loads to be disconnected from the secondary energy storage means and secondary vehicle loads using the switch. The control means and switch provide an effective means of controlling disconnection.

In an embodiment of an energy storage backup system, the measurement means may be a voltage measurement means and the system parameter may be a voltage. Some circuits where a dip in voltage occurs due to a fault would be detectable using a voltage measurement means.

In an embodiment of an energy storage backup system, the measurement means may be a current measurement means and the system parameter may be a current. Some circuits where a dip in available supply occurs (perhaps due to a current limiting device) due to a fault, would be detectable using a current measurement means.

In an embodiment of an energy storage backup system, a DC to DC (DC/DC) converter may be disposed between the secondary energy storage means and the switch. Advantageously the DC/DC converter provides an additional power source on the secondary energy storage means circuit.

In an embodiment of an energy storage backup system, the measurement means may be disposed between the secondary energy storage means and the DC/DC converter (50). This advantageously provides a local means of detecting voltage or current changes in the secondary energy storage means output.

In an embodiment of an energy storage backup system, the measurement means may be disposed between the secondary energy storage means and the switch. This advantageously provides an alternative local means of detecting voltage or current changes in the secondary energy storage means output.

In an embodiment of an energy storage backup system, the primary vehicle loads may comprise one or more of, lights, heating, instrument pack or air conditioning.

In an embodiment of an energy storage backup system, the secondary vehicle loads may comprise one or more of, vehicle park lock, brake systems or air bags. The secondary vehicle loads may be on a circuit with a potential backup power supply so are protected when a fault occurs on the primary energy storage means circuit.

In an embodiment of an energy storage backup system, the primary and/or secondary energy storage means may be one of a battery, fuel cell, super capacitor or ultra-capacitor.

In another aspect of the invention there is provided a method of controlling an energy storage backup system comprising supplying energy to both primary vehicle loads and secondary loads from both a primary energy storage means and a secondary energy storage means when a switch, disposed in series between a secondary energy storage means output and the primary energy storage means output, is in a closed position; and isolating the secondary energy storage means output from the primary energy storage means output and supplying energy only to the secondary loads from the secondary energy storage means when the switch is in an open position.

Advantageously the method may provide reliable power supply to critical systems connected to the secondary energy storage means if a fault occurs in the primary energy storage means which threaten to affect the secondary energy storage means voltage or current supply.

In an embodiment of the invention the method of controlling an energy storage backup system may comprise measuring a voltage in between the secondary energy storage means and the switch using a voltage measurement means and opening the switch if the measured voltage is below a threshold. Advantageously this may isolate any fault present on the circuit on the other side of the switch and operating the switch may disconnect any such fault from the secondary energy storage means.

In an embodiment of the invention the method of controlling an energy storage backup system may comprise measuring a current in between the secondary energy storage means and the switch using a current measurement means and opening the switch if the measured current is above a threshold. Advantageously this may isolate any fault present on the circuit on the other side of the switch and operating the switch may disconnect any such fault from the secondary energy storage means.

In an embodiment of the invention the threshold may be a value indicating a partial short to ground between the primary vehicle loads and the secondary vehicle loads. The threshold being a useful indicator and instigator to provide an input to a control system to operate the switch.

In another aspect of the invention, there is provided a control means arranged to control the switching of a switch dependent upon a value of a system parameter measured by a measurement means, control the supply of energy to both primary vehicle loads and secondary loads from both a primary energy storage means and a secondary energy storage means when the switch is in a closed position, and isolate the secondary energy storage means output from the primary energy storage means output and supply energy only to the secondary loads from the secondary energy storage means when the switch is in an open position.

In another aspect of the invention, there is provided a vehicle comprising an energy storage backup system as described herein.

In another aspect of the invention, there is provided a vehicle comprising a control means as described herein.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which;

Figure 1 shows a battery backup system according to an embodiment of the present invention

Figure 1A shows an alternate battery backup system according to an embodiment of the present invention

Figure 1B shows an example control flow method to be used with the battery backup system embodiment of figure 1

Figure 2 shows a vehicle with an energy storage backup system according to an embodiment of the present invention.

DETAILED DESCRIPTION

An energy storage backup system 5 for a vehicle 1 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figures.

Figure 1 shows an example embodiment of the energy storage backup system 5 comprising a primary energy storage means 30 and a secondary energy storage means 40. The primary energy storage means 30 may be referred to as a primary battery 30, super capacitor, ultra capacitor, or fuel cell device. The primary energy storage means 30 may supply the vehicle with a primary source of energy.

Similarly, secondary energy storage means 40 may be referred to as a secondary battery 40, super capacitor, ultra-capacitor, or fuel cell device. The secondary energy storage means may supply the vehicle with a secondary source of energy.

It could be possible for both the primary battery 30 and secondary battery 40 to provide a range of voltages from 5V to 1000v depending on the vehicle architecture.

In one example the primary battery 30 could be a standard 12v battery and the secondary battery 40 could be 300v traction battery suitable for driving a high voltage hybrid drive system for moving the vehicle.

In another example both the primary battery 30 and secondary battery 40 could be 48v batteries, the secondary battery being used as a traction battery for moving the vehicle.

Figure 1 shows primary vehicle loads 10, which could be normal 12v loads, such as lights, instrument pack and air conditioning systems for example, and secondary vehicle loads 20, which could be safety critical loads relating to braking, suspension or traction control systems for example.

A DC/DC converter 50 and switch 60 are shown connected between the secondary battery 40 and the primary battery 30. In this example the DC/DC converter 50 may be designed to convert a high voltage from the secondary battery 40 to 12v, suitable for charging the primary battery 30 and effectively to act as an alternator. The switch 60 is shown positioned between the DC/DC converter 50 and the primary battery 30 as a means of being able isolate the primary vehicle loads 10 from the secondary vehicle loads 20.

A measurement means S1 is shown positioned between the DC/DC converter 50 and the switch 60 in the example of figure 1. However, in alternative embodiments the measurement means S1 could be positioned between the DC/DC converter 50 and the secondary vehicle loads 20. The measurement means S1 may alternatively be positioned in other locations in the circuit, for example between the primary battery 30 and the primary vehicle loads 10. Other locations for the measurement means S1 are possible. The measurement means S1 could be a voltage measurement device or sensor or a current measurement device or sensor.

An electrical connection 18c is made between the conductors 18a, 18b which ensure the secondary vehicle loads 20 receive power from the DC/DC converter 50 output when the switch 60 is in an open position. The conductors may be wires, cables or busbars for example.

A control means in the form of a controller 80 is shown in figure 1 as having three control connections to the main circuit being control connections 82, 84, 86. Control connection 82 could be collecting voltage, current and power flow direction readings from the primary battery 30, control connection 84 connected to the switch 60 could be an actuation signal to either open or close the switch 60, control connection 86 is connected to sensor S1 and could be measuring voltage or current, and detecting flow direction of power between the DD/DC converter 20 and the primary battery system 30.

Conductors 12, 14, 16, 18a, 18b may be dual core cables and connect the example 12v system components as is conventional.

An energy storage backup system 5 for a vehicle 1 is shown in the example embodiment of figure 1 and will now be described using figure 1B with respect to how the system could operate.

In block 100 of the method, the controller 80 sets the switch 60 position to closed.

In block 110 of the method, the system initialises the DC/DC converter 50 to convert voltage from the secondary battery 40 to the voltage expected by the primary and secondary loads 10, 20.

In block 120 of the method, the controller 80 reads the value of the system parameter from sensor S1.

In block 130 of the method, if the controller determines the value of the system parameter from sensor S1 shows a current greater than a threshold or a voltage lower than a first threshold, then the switch 60 is opened at block 140.

In block 130, if the controller determines the value of the system parameter from S1 shows a current lower than a threshold or a voltage higher than a first threshold, then the switch 60 remains closed and the controller returns to block 120 to read the system parameter from sensor S1 again.

The blocks illustrated in figure 1B may represent steps in a method. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some steps to be omitted.

In a normal operating condition the secondary battery 40 could be feeding high voltage into the DC/DC converter 50 which could output 12v DC to the cables 18a, 18b. The switch 60 would be in the closed position allowing 12v to feed into the primary battery 30. In this condition both the primary and secondary vehicle loads 10, 20 would be receiving the same voltage via cables 12, 18a respectively and it would be possible for the primary vehicle loads 10 to receive power from either the primary battery 30 or the DC/DC converter 50 via the switch 60. It would also be possible for the secondary vehicle loads 20 to receive power from either the primary battery 30 or the DC/DC converter 50 via the switch 60. Current could flow either way through the closed switch 60 dependent upon the power requirements of the primary vehicle loads 10 and the secondary vehicle loads 20.

The switch 60 may be either open or closed as controlled by the controller 80. If the switch 60 is closed then the cables 14, 16 will be electrically connected such that current can flow between them in either direction. Under no fault conditions the DC/DC converter 50 is able to both charge the primary battery 30 and supply the secondary vehicle loads 20. The primary battery 30 may also supply the secondary vehicle loads 20.

Another embodiment of an energy storage backup system 5A is shown in figure 1A which shows a very similar arrangement to figure 1.

Figure 1A has like numbers to figure 1 where the components are the same. In the figure 1A embodiment the DC/DC converter is not needed as the primary battery 30 and the secondary battery 40 may have the same DC voltage output. The operation of the energy storage backup system 5A in figure 1A is exactly the same as figure 1 although there is no necessity to have voltage conversion provided by the DC/DC converter 50 because the primary battery 30 and secondary battery 40 are the same voltage and power is able to flow from either the primary battery 30 or secondary battery 40 to either of the primary or secondary vehicle loads 10, 20 as would be known by a person skilled in the art.

It is an aim of the invention to detect when system voltage dips or current peaks occur for any reason and to protect critical loads in the system from loss of power. In this example the critical loads are grouped in with the secondary vehicle loads 20.

Fault conditions

A number of possible fault conditions could occur which would cause voltage dips in the system and importantly could put the supply of power to the secondary vehicle loads 20 at risk. Such fault conditions may include a short, and an open circuit fault.

Short

In an embodiment, if the voltage at cable 16 falls below a first threshold perhaps due to a partial short to ground in any of the cables 12, 14, 16 or an unexpectedly high load occurs in the primary vehicle loads 10 then the sensor S1 could detect a voltage dip below a first threshold and pass the signal along the control connection 86 to the controller 80. The controller could then respond by opening the switch 60 using the control connection 84, thus isolating the primary battery 10 and primary vehicle loads 10 from the DC/DC converter 50 output and the secondary vehicle loads 20.

When the switch 60 is open the secondary vehicle loads 20 are protected from any faults connected to the primary battery 30 and the DC/DC converter 50 is able to supply power to the secondary vehicle loads 20 to keep the critical vehicle systems powered while the vehicle is manoeuvred to, or finds, a safe place to stop.

In another embodiment, a method of controlling an energy storage backup system 5 comprises measuring the current in between the secondary energy storage means 40 and the switch 60 using a current measurement means S1 and opening the switch 60 if the measured current is above a threshold. A high current measured from the DC/DC converter 50 for example could indicate one of the primary loads was demanding a level of current indicative of a fault, dependent upon which primary vehicle loads 10 were known to be switched on. As an example, it may be known that only the vehicle lights and instrument pack were initiated as primary vehicle loads which could demand 10 amps, however if the DC/DC converter 50 was outputting 100 amps and the secondary vehicle loads were known to be taking 30 amps only, then this would indicate a fault level of current of 70 amps going into the primary battery 30 through the switch 60. This fault condition could then initiate the switch 60 to open.

In another embodiment, a method of controlling an energy storage backup system 5 is possible, wherein the current or voltage being measured using a current or voltage measurement means S1 could indicate a partial short to ground between the primary vehicle loads 30 and the secondary vehicle loads 40. In this case the controller 80 would need to evaluate whether the current drain was excessively high or whether the voltage level was low enough to warrant opening the switch 60 to protect the secondary vehicle loads 20. Thresholds may be set to determine or define the limits of current drain and/or limits of the voltage level where the switch 60 may be opened.

The primary vehicle loads 10 may still be subject to the fault and the primary battery 30 may or may not be able to support the less critical systems but this will not prevent the vehicle from being driven to a safe place to stop or prevent the vehicle from being parked.

Open circuit

If an open circuit fault occurs in any of cables 12, 14, 16 due to, for example, damage caused in an accident, then the controller 80 could be able to compare the voltage or current signals on control connections 82, 86 to determine if power was still flowing to a localised fault between the positive and negative sides of the 12v circuit. In this condition it would be possible to open the switch 60 to prevent any further power being transferred from the DC/DC converter 50 to the fault occurring in any of cables 12, 14, 16. Again with the switch 60 open, the critical secondary loads 20 could be supported taking power from the DC/DC converter 50 via cables 18a, 19 and could be maintained as long as there was power still flowing from the secondary battery 40.

The controller 80 is powered by both the primary battery 10 and the DC/DC converter 50 with a diode circuit as shown in figure 1 which could include diodes 51, 52 that prevent back feed from the DC/ DC converter to the primary battery and vice-versa. This assures stable controller 80 supply during fault conditions. In an embodiment the diodes 51,52 could be an integral part of a MOFSET or other electrical component.

An energy storage backup system 5, 5A for a vehicle is shown in figure 2.

According to a further aspect of the invention there is provided a computer program that, when run on at least one electronic processor or processing circuitry, causes a system to perform the method disclosed herein. The control means 80 may comprise an electronic processor or processing circuitry.

It will be appreciated that embodiments of the present invention can be realised in the form of hardware, software or a combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs that, when executed, implement embodiments of the present invention. Accordingly, embodiments provide a program comprising code for implementing a system or method as claimed in any preceding claim and a machine readable storage storing such a program. Still further, embodiments of the present invention may be conveyed electronically via any medium such as a communication signal carried over a wired or wireless connection and embodiments suitably encompass the same.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

CLAIMS:

1. An energy storage backup system for a vehicle comprising:

a primary energy storage means for supplying energy to one or more primary vehicle loads;

a secondary energy storage means for supplying energy to one or more secondary vehicle loads;

a switch in series between the secondary energy storage means output and the primary energy storage means output; and a connection between the secondary energy storage means and the switch, connected to the secondary vehicle loads;

wherein, if the switch is in a closed position, both the primary energy storage means and the secondary energy storage means are connected to both the primary vehicle loads and secondary vehicle loads, and if the switch is in an open position, the secondary energy storage means output is isolated from the primary energy storage means output, and the secondary energy storage means supplies energy only to the secondary vehicle loads.

2. An energy storage backup system for a vehicle as claimed in claim 1, comprising a measurement means for measuring a value of a system parameter.

3. An energy storage backup system for a vehicle as claimed in claim 2, comprising control means to control the switching of the switch dependent upon the value of the system parameter measured by the measurement means.

4. An energy storage backup system as claimed in claim 2 or claim 3, wherein the measurement means is a voltage measurement means and the system parameter is a voltage.

5. An energy storage backup system as claimed in claim 2 or claim 3, wherein the measurement means is a current measurement means and the system parameter is a current.

6. An energy storage backup system as claimed in any preceding claim, wherein a DC/DC converter is disposed between the secondary energy storage means and the switch.

7. An energy storage backup system as claimed in claim 6 when also dependent on any of claims 2 to 5, wherein the measurement means is disposed between the secondary energy storage means and the DC/DC converter.

8. An energy storage backup system as claimed in claim 6 when also dependent on any of claims 2 to 5, wherein the measurement means is disposed between the secondary energy storage means and the switch.

9. An energy storage backup system as claimed in any previous claim, wherein the primary vehicle loads comprise one or more of, lights, heating, instrument pack or air conditioning.

10. An energy storage backup system as claimed in any previous claim, wherein the secondary vehicle loads comprise one or more of, vehicle park lock, brake systems or air bags.

11. An energy storage backup system as claimed in any previous claim, wherein the primary and/or secondary energy storage means is one of a battery, fuel cell, super capacitor or ultra-capacitor.

12. A method of controlling an energy storage backup system comprising:

supplying energy to both primary vehicle loads and secondary loads from both a primary energy storage means and a secondary energy storage means when a switch, disposed in series between a secondary energy storage means output and the primary energy storage means output, is in a closed position; and isolating the secondary energy storage means output from the primary energy storage means output and supplying energy only to the secondary loads from the secondary energy storage means when the switch is in an open position.

13. A method of controlling an energy storage backup system as claimed in claim 12, comprising measuring a voltage in between the secondary energy storage means and the switch using a voltage measurement means and opening the switch if the measured voltage is below a threshold.

14. A method of controlling an energy storage backup system as claimed in claim 12, comprising measuring a current in between the secondary energy storage means and the switch using a current measurement means and opening the switch if the measured current is above a threshold.

15. A method of controlling an energy storage backup system as claimed in claim 13 or claim 14, wherein the threshold is a value indicating a partial short to ground between the primary vehicle loads and the secondary vehicle loads.

16. A control means arranged to:

control the switching of a switch dependent upon a value of a system parameter measured by a measurement means;

control the supply of energy to both primary vehicle loads and secondary loads from both a primary energy storage means and a secondary energy storage means when the switch is in a closed position;

isolate the secondary energy storage means output from the primary energy storage means output and supply energy only to the secondary loads from the secondary energy storage means when the switch is in an open position.

17. A vehicle comprising an energy storage backup system means according to any of claims 1 to 11 or a control means according to claim 16.