GB2566308A

GB2566308A - Battery management system

Info

Publication number: GB2566308A
Application number: GB1714503.8A
Authority: GB
Inventors: Shaw Robin; Irish Stephen
Original assignee: Hyperdrive Innovation Ltd
Current assignee: Hyperdrive Innovation Ltd
Priority date: 2017-09-08
Filing date: 2017-09-08
Publication date: 2019-03-13
Anticipated expiration: 2037-09-08
Also published as: GB201714503D0; GB2566308B

Abstract

A battery management system 100 for controlling charging currents to a plurality of cells 121-124 of a battery based on the estimated temperature of those cells. The battery management system comprises a sensing interface 108 adapted to obtain temperature signals from a plurality of temperature sensors 131-134 each associated with one of the cells. The battery management system is also configured to detect a fault state in one of the sensors, for example by obtaining from the sensor a trigger signal indicating a fault. A fault state may also be detected by monitoring the temperature signal over a period of time and determining whether the variation in the signal exceeds a threshold and/or by comparing a temperature signal from the sensor with that of at least one neighbouring cell and determining if the difference exceeds a threshold value. If a fault state is detected, the system is further configured to provide a charging current to the affected cell based on an estimated temperature which it determines based on the temperature of at least one neighbouring cell, for example by interpolating the temperature signal from the sensors of two neighbouring cells. The system may provide an alert signal to indicate a fault.

Description

Battery Management System

Field

The present disclosure relates to battery management systems, and more particularly to methods and apparatus for controlling the charging of cells of a battery based on their temperature.

Background

Scalable battery systems, such as the 48 volt modular lithium ion energy storage system available from Hyperdrive

Innovation

Limited (Future

Technology Centre,

Barmston Court,

Nissan Way

Sunderland,

Tyne and Wear,

SR5 3NY,

UK) , may be used in a wide variety of circumstances .

For example, they may be deployed in stationary energy storage systems, such as may be used in commercial facilities to mitigate the effects of failures in mains power supply.

These and other types of battery systems may be deployed in arrays in which a number of batteries are connected together in parallel and/or series. This may be useful in a wide variety of circumstances, and particularly where there is likely to be high current demand.

Lithium ion (Li-ion) battery technology is now the battery of choice, both in on-highway and off-highway automotive applications, and in other energy storage systems. Such energy storage systems may be used in energy supply systems to support

-2electricity generation (e.g. in domestic alternative energy installations), or with vehicle carried generator units to mitigate the effects of interruptions in the main grid supply of electricity. In such circumstances arrays of batteries connected in parallel and/or series may be of particular utility.

Li-ion battery technology has significant advantages with respect to :

• battery life (number of charge-discharge cycles) • self-discharge rate and storage life • high cell voltage; and, • energy density.

It is often necessary to monitor the temperature of the cells of such batteries using sensors. In some circumstances these sensors may malfunction, causing potentially hazardous situations to arise .

Summary

Aspects and examples of the present disclosure aim to address at least a part of the above described technical problems and/or related problems. Aspects of the invention are as set out in the independent claims and optional features are set out in the dependent claims.

An aspect of the disclosure provides a battery management system for balancing a plurality of cells of a battery, the battery

-3management system comprising a sensing interface adapted to obtain temperature signals from a plurality of temperature sensors each associated with one of the cells; wherein the battery management system further comprises a controller operable to detect a fault state in one of the sensors; and configured to determine, in response to detecting a fault state in one of the sensors, an estimated temperature of the associated cell based on the temperature of at least one neighbouring cell; and control current to the cells based on the estimated temperature.

The current to a cell may be positive, in the case of charging, or negative in the case of discharging. For example the discharging current may be a reverse current that flows in the opposite direction to the charging current. Controlling may comprise limiting the maximum magnitude and/or the sign of this current.

Balancing the cells may comprise providing equivalent energy in the cells. It will be appreciated that providing equivalent energy to the cells may comprise providing, for example, an equivalent voltage or an equivalent charging state across the cells of the battery.

Balancing the cells may comprise providing charging and/or discharging currents to the cells. Charging and/or discharging currents to each cell may be controlled by the battery management system and may be based on the temperature of that cell, a group of cells or the temperature of the battery as a whole. For example the battery management system may control the rate of

-4charging and/or discharging of a cell based on the temperature of that cell, a group of cells, or the temperature of the battery as a who1e.

Detecting a fault state in one of the sensors may comprise obtaining, from the sensor, a trigger signal indicating a fault.

Detecting a fault state in one of the sensors may comprise determining if the difference between the temperature signal from the sensor and the temperature signals from sensors of at least one neighbouring cell is larger than a threshold value.

Detecting a fault state in one of the sensors may comprise obtaining a temperature signal from the sensor over a time period and determining whether the temperature varies by more than a threshold amount over the time period.

The estimated temperature may be based on the temperature signals from sensors associated with at least two neighbouring cells.

Determining the estimated temperature may comprise interpolating the temperature signals from the sensors of two neighbouring cells .

Determining the estimated temperature may comprise extrapolating the temperature signals from the sensors of at least one neighbouring cell. For example the BMS may determine the estimated temperature for the cell associated with a faulty sensor based on the position in the battery of that cell and the

-5positions in the battery of other cells in the battery, by extrapolating the temperature signals received from the temperature sensors other cells of the battery. The BMS may determine an estimated temperature for a cell by extrapolation in the event that the cell has only 1 neighbour. The BMS may determine an estimated temperature for a cell based on a combination of interpolation and extrapolation of temperature signals of other cells in the battery.

Determining the estimated temperature may comprise selecting the highest temperature indicated by the temperature signals obtained from the sensors of the at least one neighbouring cell.

The battery management system may, in response to detecting a fault state in one of the sensors, be configured to reduce the current provided to the cell associated with that sensor. For example the current provided to the cell may be a charging current and the battery management system may be configured to reduce the charging current provided to the cell or to provide a discharging current to the cell in response to detecting a fault state in the sensor associated with that cell.

In response to detecting a fault state in one of the sensors, the battery management system may be configured to provide an alert signal to a user interface to indicate the fault to a user.

The battery management system may be configured to control the current to a cell according to a first control scheme or a second control scheme; wherein, in the first control scheme the battery

-6management system is configured to control the current to the cell based on the temperature signal obtained from the sensor associated with the cell; and, in the second control scheme the battery management system is configured to control the current to the cell based on the determined estimated temperature of the associated cell.

In response to detecting a fault state in the sensor associated with the cell, the battery management system may be configured to switch from controlling the current to the cell according to the first control scheme to controlling the current to the cell according to the second control scheme.

Aspects of the invention may be provided in conjunction with each other and features of one aspect may be applied to other aspects.

Brief Description of Drawings

Embodiments of the disclosure will now be described in detail with reference to the accompanying drawings, in which:

Figure 1 shows a battery comprising a battery management system; and

Figure 2 is a flow chart showing a method to be carried out by battery management system.

In the drawings like reference numerals are used to indicate like elements .

Specific Description

-7Described below with references to Figures 1 and 2 is a battery management system (BMS) for controlling the currents (e.g. the charging or discharging currents) provided to cells of a battery. The battery cells each have an associated temperature sensor configured to provide temperature signals indicating the temperature of the cell to a sensing interface of the BMS. The BMS is configured to control the current to each of the cells based on their temperature, and is also operable to detect a fault in one of the sensors. In response to detecting a fault, the BMS may determine, for the cell associated with the faulty sensor, an estimated temperature based on the temperature of one or more neighbouring cells. A charging or discharging current may then be provided to the cell with the faulty sensor based on the estimated temperature.

Figure 1 shows a battery 100 comprising a plurality of energy storage cells 121, 122, 123, 124, connected together in series between a positive terminal 104, and a negative terminal 105. A current sensor 111 is provided between the cells 121-124 and the positive terminal 104. The terminals may be carried by a housing 103 of the battery 100. The battery 100 also comprises a battery management system 102. The housing 103 may encapsulate the cells 5-15 and the battery management system 102.

Each of the cells 121-124 are coupled to an associated temperature sensor 131, 132 133, 134. The cells 121-124 may be any appropriate cell for electrical energy storage, and generally they are rechargeable. For example they may comprise Li-Ion

-8cells. It will be appreciated that each such cell may itself comprise a number of smaller cells - but, other than in so far as explained above, the internal structure of the cells 121-124 is not material.

The BMS 102 comprises a battery fuel gauge 109, a controller 107, a CANBUS interface 110, a temperature sensing analogue to digital converter (ADC) 106, and an analogue front end 44. The analogue front end 108 is connected to the controller 107. The controller 48 is also connected to the CANBUS interface 110, and to the temperature sensing ADC 106. The temperature ADC 106 is connected to the temperature sensors 131-134 of each of the cells 121-124.

The temperature sensors 131-134 in Figure 1 are configured to provide an analogue signal to the temperature sensing ADC 106, which in turn provides a digital signal to the controller 107. However, it will be appreciated that in other examples the temperature sensors may provide digital signals indicating the temperature of the cells directly to a controller, such that a temperature sensing ADC is not necessary.

The BMS 102 also comprises a set of FETs 141, 142, 143, 144 and discharge resistances. One FET 141-144 and one discharge resistance is connected in parallel with each cell 121-124.

The analogue front end 108 provides an analogue to digital and digital to analogue converter (ADC/DAC) for the battery management system 102. Accordingly it comprises a plurality of voltage sensing terminals for obtaining analogue voltage signals from each of the cells 121-124 (each indicating the voltage

-9across a corresponding one of the cell modules) . The analogue front end 108 also comprises a set of voltage outputs, each operable to provide a controllable voltage signal. The voltage sensing terminals of the analogue front end 108 are connected for sensing the voltage across each of the cells 121-124 of the battery. Its voltage outputs are connected to the gate terminals of each of the FETs 141-144. The analogue front end 108 is also configured to provide cell voltage data, based on the voltage signals from each of the cells 121-124 to the controller 107.

The battery fuel gauge 109 is connected to the current sensor 111 and to the controller 107. The battery fuel gauge 109 is configured to determine a state of charge of the battery 100 based on measuring the flow of current into and out from the battery 100.

The CANBUS interface 110 is adapted to communicate, via a controller area network, with other CANBUS enabled devices coupled to such a network.

The controller 107 may also be operable to communicate with a battery charger via the CANBUS interface 110 to send charging requests to the charger - e.g. to request a particular current and/or a particular voltage. The controller 107 may be configured to determine the charging requests based on the cell module voltage data and/or based on state of charge data obtained from the battery fuel gauge 109.

The controller 107 may also be configured to obtain cell module

-10voltage data from the analogue front end 108, and to obtain cell module temperature data from the temperature ADC 106. The controller 48 is also configured to control the FETs 141-144 via the analogue front end 108 based on the cell module voltage data to balance the cells 121-124 e.g. so that the voltage across each of the cell modules is equal across the cells. Balancing may be performed according to any one of a number of balancing schemes, but typically the FETs 141-144 may be operated via the analogue front end 108 to discharge current through one of the FETs 141144 to lower the voltage of the corresponding cell- e.g. to equalise it with a voltage across the other cells. The controller 107 may also be operable to communicate with a battery charger via the CANBUS interface 110 to send charging requests to the charger - e.g. to request a particular current and/or a particular voltage. The controller 107 may be configured to determine the charging requests based on the cell module voltage data and/or based on state of charge data obtained from the battery fuel gauge 109.

The temperature sensing ADC 106 provides a sensing interface for the BMS 102 and is configured to provide temperature signals to the controller 48 based on temperature signals obtained from the temperature sensors 131-134 of the cells 121-124.

The controller 107 is configured to obtain the cell temperature signals from the temperature sensing ADC 106, and balance the cells 121-124, e.g. by controlling the current provided to each cell 121-124, based on the temperature signals obtained from their temperature sensors 131-134.

-11 In a normal operating mode, the BMS 102 may control the charging level of each cell 121-124 based on the temperature of that cell. The temperature sensing ADC 106 obtains temperature signals from each of the temperature sensors 131-134 of the cells 121-124, and provides the signals to the controller 107. Based on the temperature of each cell 121-124 indicated by the signal from the sensors 121-124, the controller 107 is configured to control the current to each of the cells 121-124. In particular, as described above, the controller 107 is electrically coupled to the gate of the plurality of FETs 141-144 via the analogue front end 108, such that by increasing or decreasing the voltage supplied to the gate of the FETs 141-144, the controller can charge and discharge each of the cells 121-124, based on the temperature of the cells 121-124, as indicated by the temperature signals obtained from the temperature sensors 131-134. For example the controller 107 may be configured to reduce the current provided to a cell or to discharge a cell as the temperature of the cell increases or if the temperature of the cell goes above a threshold value. The controller 107 may also be configured to turn off or isolate a cell if the controller determines, based on the temperature signal obtained from the sensor of that cell, that the temperature of the cell is above a certain threshold value. Controlling the current supplied to each cell based on their temperature may prevent overheating of the cell and the battery 100 as a whole and may improve the safety of the battery 100.

The BMS 102 is configured to detect a fault state in any of the temperature sensors 131-134. A fault state in a sensor may

-12 comprise, for example, an inaccurate measurement of temperature,

providing	an unstable signal, or	the	sensor	not providing	a
signal at	all.
Each of	the sensors 131-134 may	be	configured to provide	a
trigger message indicating a fault	state	to the	controller 107	in

the event that they experience a fault.

The BMS 102 may also be configured to detect a fault in a sensor by comparing the temperature signals from that sensor with the temperature signals from the sensors of at least two neighbouring cells. For example, to detect a fault in temperature sensor 133 the controller 107 may compare a temperature signal from sensor 133 with signals from temperature sensors 132 and 134. If the difference between the temperature signal from sensor 133 and the temperatures signal from sensors 132 and 134 is more than a threshold amount, the controller detect a fault in sensor 133.

The BMS 102 may also detect a fault in a sensor if the temperature signal provided by that sensor is unstable or varies more than a threshold amount over time. The controller 107 may obtain temperature signals from each temperature sensor 131-134 continuously or at time intervals, and may detect a fault in one of the temperature sensors 131-134 if the temperature signal from that sensor varies by more than a threshold amount over a set time period.

In response to detecting a fault in one of the sensors 121-124 the BMS 102 may provide an alert to a user. For example, the

-13controller 107 may provide an alert signal via the CANBUS interface 110 to a connected user interface such as a display (not shown) . The display may identify which of the sensors is in a fault state and the nature of the fault.

The BMS 102 is also configured to modify the current to a cell in response to detecting a fault in one of the sensors. For example the controller 107 may reduce the current provided to a cell in response to detecting a fault in the temperature sensor of that cell.

The BMS 102 is configured to determine an estimated temperature for a cell in response to detecting a fault in the cell's associated temperature sensor. The estimated temperature for the cell is based on the temperature of at least one neighbouring cell. For example, if the BMS 102 detects a fault in temperature sensor 133, the controller 107 may determine an estimated temperature for cell 123 based on the temperature signals obtained from the sensors 132, 134 of its neighbouring cells 122, 124. For example, the controller 107 may determine the estimated temperature of the cell 123 by calculating an average of the temperatures indicated by the sensors 132, 134 of the neighbouring cells 122, 124.

Alternatively, the controller 107 may determine the estimated temperature of a cell 123 by simply selecting the highest temperature indicated by the sensors 132, 134 of the neighbouring cells 122, 124. If a fault is detected in the sensor of a cell with only 1 neighbouring cell, the BMS may select the indicated

-14temperature of this neighbouring cell as the estimated temperature of the cell.

The BMS 102 may interpolate the temperature signals from the temperature sensors of other cells to determine the estimated temperature of a cell. For example the controller

107 may determine an estimated temperature for a cell by analysing the temperatures of the other cells in the battery 100, and interpolating them (e.g. linearly, polynomially) to obtain a value for the estimated temperature of the cell. The BMS 102 may interpolate the temperatures of the cells neighbouring the cell with a sensor in a fault state, or it may interpolate based on the temperatures of more cells, for example based on all the cells in the battery 100, or a selection of other cells in the battery 100.

The BMS

102 may also determine an estimated temperature for the cell by extrapolation, based on the temperature signals of other cells in the battery. For example the BMS 102 may determine the estimated temperature for the cell associated with a faulty sensor based on the position in the battery 100 of that cell and the positions in the battery 100 of other cells in the battery 100, by extrapolating the temperature signals received from the temperature sensors of other cells of the battery 100. The BMS 102 may determine an estimated temperature for a cell using extrapolation in the event that the cell has only 1 neighbour. For example, in the event that a cell 121 associated with a faulty sensor 131 is at the end of a string of cells 121-124 in the battery 100, the BMS 102 may determine an estimated temperature for the cell 121 by extrapolating some or all of the temperature signals received from the temperature

-15sensors 132-134 of the other cells 122-124 of the battery 100.

The BMS balances the cells of the battery based on the estimated temperature. The BMS can therefore continue to balance cells even if a temperature sensor develops a fault.

The BMS is therefore configured to control the current to a cell according to two control schemes. The first control scheme relates to a normal mode of operation, in which the BMS controls the current to a cell based on the temperature signal from the sensor associated with the cell. The second control scheme relates to a mode of operation when a fault state is detected in one of temperature sensors. In this case the BMS determines an estimated temperature of the associated cell based on the temperature of at least one neighbouring cell, and provides a current to the cell based on this estimated temperature. In response to detecting a fault state in a sensor, the BMS switches from controlling the current associated cell according to the first control scheme to controlling the current to the cell according to the second control scheme.

Figure 2 is a flowchart illustrating the steps of operating a BMS to control the current provided to cells according to the two different modes. As Figure 2 shows, the BMS obtains temperature signals from all the sensors (201) .

If no fault is detected in controls the current to that cell based on the temperature signal from the temperature sensor of that cell (205) . If a fault is detected in a sensor of a cell (202) , the BMS determines an estimated temperature of that cell

-16based on the temperature of at least one neighbouring cell (203), and controls the current to that cell based on the estimated temperature (204) .

It will be appreciated in the context of the present disclosure that controlling current to the cell may comprise controlling the rate of charging or discharging and/or may comprise balancing the cells based on their temperature.

It will be appreciated that although Figure 1 shows a battery management system comprising an analogue front end, a temperature sensing ADC, a battery fuel gauge, and a CANBUS interface, these components are not necessary and their function may instead be performed by other battery managing means. For example it will be appreciated that the temperature sensors could provide digital signals to the controller directly instead of via a temperature sensing ADC.

It will be appreciated from the discussion above that the embodiments shown in the Figures are merely exemplary, and include features which may be generalised, removed or replaced as described herein and as set out in the claims. With reference to the drawings in general, it will be appreciated that schematic functional block diagrams are used to indicate functionality of systems and apparatus described herein. It will be appreciated however that the functionality need not be divided in this way, and should not be taken to imply any particular structure of hardware other than that described and claimed below. The function of one or more of the elements shown in the drawings may

-17be further subdivided, and/or distributed throughout apparatus of the disclosure. In some embodiments the function of one or more elements shown in the drawings may be integrated into a single functional unit.

In some examples the functionality of the controller may be provided by a general purpose processor, which may be configured to perform a method according to any one of those described herein. In some examples the controller may comprise digital logic, such as field programmable gate arrays, FPGA, application specific integrated circuits, ASIC, a digital signal processor, DSP, or by any other appropriate hardware. In some examples, one or more memory elements can store data and/or program instructions used to implement the operations described herein. Embodiments of the disclosure provide tangible, non-transitory storage media comprising program instructions operable to program a processor to perform any one or more of the methods described and/or claimed herein and/or to provide data processing apparatus as described and/or claimed herein. The controller may comprise an analogue control circuit which provides at least a part of this control functionality. An embodiment provides an analogue control circuit configured to perform any one or more of the methods described herein.

The above embodiments are to be understood as illustrative examples. Further embodiments are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one

- 18-

or more features of any other of the embodiments, or any

combination of	any other of the embodiments. Furthermore,
equivalents and	modifications not described above may also be
employed without	departing from the scope of the invention, which

is defined in the accompanying claims.

Claims

1. A battery management system for balancing a plurality of cells of a battery, the battery management system comprising a sensing interface adapted to obtain temperature signals from a plurality of temperature sensors each associated with one of the cells; wherein the battery management system further comprises a controller operable to:

detect a fault state in one of the sensors; and configured to determine, in response to detecting a fault state in one of the sensors, an estimated temperature of the

associated cell based on the temperature of at least one neighbouring cell; and control current to the cells based on the estimated temperature.

2 . The battery management system of claim 1, wherein detecting a fault state in one of the sensors comprises obtaining,

from the sensor, a trigger signal indicating a fault.

3. The battery management system of any preceding claim, wherein detecting a fault state in one of the sensors comprises determining if the difference between the temperature signal from the sensor and the temperature signals from sensors of at least one neighbouring cell is larger than a threshold value.

4. The battery management system of any preceding claim, wherein detecting a fault state in one of the sensors comprises obtaining a temperature signal from the sensor over a time period and determining whether the temperature varies by more than a threshold amount over the time period.

5. The battery management system of any preceding claim, wherein the estimated temperature is based on the temperature signals from sensors associated with at least two neighbouring cells.

6. The battery management system of any preceding claim, wherein determining the estimated temperature comprises interpolating the temperature signals from the sensors of two neighbouring cells.

7. The battery management system of any preceding claim, wherein determining the estimated temperature comprises extrapolating the temperature signals from the sensors of at least one other cell of the battery.

8. The battery management system of any preceding claim, wherein determining the estimated temperature comprises selecting the highest temperature indicated by the temperature signals obtained from the sensors of the at least one neighbouring cell.

9. The battery management system of any preceding claim, wherein, in response to detecting a fault state in one of the sensors, the battery management system is configured to reduce the charging current provided to the cell associated with that sensor.

10. The battery management system of any preceding claim; wherein, in response to detecting a fault state in one of the sensors, the battery management system is configured to provide an alert signal to a user interface to indicate the fault to a user.

11. The battery management system of any preceding claim, wherein the battery management system is configured to control the charging current to a cell according to a first control scheme or a second control scheme; wherein in the first control scheme the battery management system is configured to control the charging current to the cell based on the temperature signal obtained from the sensor associated with the cell; and in the second control scheme the battery management system is configured to control the charging current to the cell based on the determined estimated temperature of the associated cell.

12. The battery management system of claim 11 wherein, in response to detecting a fault state in the sensor associated with the cell, the battery management system is configured to switch from controlling the charging current to the cell according to the first control scheme to controlling the charging current to the cell according to the second control scheme .

13. A method of balancing a plurality of cells of a battery of those cells, the method comprising:

detecting a fault state in one of a plurality of sensors associated with the cells;

determining, in response to detecting a fault state in one of the sensors, an estimated temperature of the associated cell based on the temperature of at least one neighbouring cell; and control current to the cells based on the estimated temperature.

14. The method of claim 13, wherein detecting a fault state in one of the sensors comprises obtaining, from the sensor, a trigger signal indicating a fault.

15. The method of claim 13 or 14, wherein detecting a fault state in one of the sensors comprises determining if the difference between the temperature signal from the sensor and the temperature signals from sensors of at least one neighbouring cell is larger than a threshold value.

16 .

The method of any of claims

13 to 15, wherein detecting a fault state in one of the sensors comprises obtaining a temperature signal from the sensor over a time period and determining whether the temperature varies by more than a threshold amount over the time period.

17. The method of any of claims 13 to 16, wherein the estimated temperature is based on temperature signals from associated with at least two neighbouring cells.

18. The method of any of claims 13 to 17, wherein determining the estimated temperature comprises interpolating the temperature signals from the sensors of two neighbouring cells .

19. The method of any of claims 13 to 18, wherein determining the estimated temperature comprises extrapolating the temperature signals from the sensors of at least one other cell of the battery.

20. The method of any of claims 13 to 19, wherein determining the estimated temperature comprises selecting the highest temperature indicated by the temperature signals obtained from the sensors of the at least one neighbouring cell.

21. The method of any of claims 13 to 20, further comprising, in response to detecting a fault state in one of the sensors, reducing the charging current provided to the cell associated with that sensor.

22. The method of any of claims 13 to 21; further comprising, in response to detecting a fault state in one of the sensors,

providing an alert signal to a user interface to indicate the fault to a user.

23 . The method of any of claims 13 to 22, comprising controlling

-24the charging current to a cell according to a first control scheme or a second control scheme; wherein the first control scheme comprises controlling the charging current to the cell based on the temperature signal obtained from the sensor associated with the cell; and the second control scheme comprises controlling the charging current to the cell based on the determined estimated temperature of the associated cell.

24. The method of claim 23, further comprising, in response to detecting a fault state in the sensor associated with the cell, switching from controlling the charging current to the cell according to the first control scheme to controlling the charging current to the cell according to the second control scheme.

25. A computer program product comprising program instructions configured to program a processor to perform the method of any of claims 13 to 24.

26. A processor configured to perform the method of any of claims 14 to 25.