GB2584293A

GB2584293A - Battery pack controller - safety and reliability of battery pack

Info

Publication number: GB2584293A
Application number: GB1907504.3A
Authority: GB
Inventors: Gupta Sanjay
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-05-28
Filing date: 2019-05-28
Publication date: 2020-12-02
Anticipated expiration: 2039-05-28
Also published as: GB201907504D0; GB2584293B

Abstract

A battery pack 100 includes multiple series-connected battery modules 200 and a battery pack controller 140. Each group of battery modules 200 includes a switch or relay 133 which switches between connecting the battery module group 200 into the series circuit or bypassing the battery module group 200 thus isolating it from the series circuit. The isolated battery module group 200 has a voltage below the safe extra low voltage (SELV) level. The battery pack controller 140 may operate the switch 133 when the vehicle is switched off, in the event of a crash, or when a battery module 200 is determined to have failed. Battery module failure is determined by monitoring the state of health, impedance, thermal properties, and other factors relating to the battery module 200. The battery modules 200 may be submerged in a dielectric liquid which prevent fire and thermal runaway. Pressure sensors and level sensors are used to monitor the dielectric liquid and to determine whether gas must be released.

Description

-riphone

Title eldescription

Battery pack controller-safety and reliability of battery pack Technical Fiele Large battery packs used in large electric vehicles e.g. cars, trucks, buses, vans, trains. This invention relates to large battery pack technology.

For large battery packs which supply large energy and high peak power, safety and reliability of the battery pack are equally important as the thermal management and charging of the batteries. Large battery packs produce very high voltages e.g. 800v to deliver high energy in 100s of KW. This high voltage poses significant risk to the occupants of the vehicle and the emergency services if the vehicle is involved in an accident.

Large battery packs typically involves lots of battery modules (BMs) electrically connected in series and parallel, to deliver large energy. Failure of one of the BMs which creates a electrical series link with other modules can make the entire battery pack unusable. Thus one BM connected in series, which in some cases contributes less than 1% of the total energy of the battery pack, can bring down the entire battery pack. Also the failure or thermal runaway of a BM can create a fire hazard for the battery pack, electric vehicle and its occupants.

How tins: invention selves the Cechnikal prifinems, and how it. diffenmt This invention solves the current technical problems through many innovative steps: 1. High voltage safety-This innovation packs the batteries/capacitors in the BMs and relays/power switches are added in parallel to a group of BMs such that when the relay is switched OFF the group of BMs are taken out of the series circuit and when the relay is switched ON the group of BMs are included in the electrical series circuit. The battery pack controller switches ON or OFF upon trigger from battery pack controller. Battery pack takes away the heat emanating from the power relays and protects the batteries from the heat produced by the power relays.

2. Reliability of the battery pack -All the batteries within the battery pack do not age equally and this results in some batteries and hence some BMs losing capacity sooner than the rest of the BMs. Weak BMs in the series circuit also deteriorate faster. This leads to thermal runaway and risk of fire if the weak BMs are continued to be used in the series circuit. This innovation proactively takes the weakest BMs out of the series circuit and this extends the life the battery pack and improves the capacity utilisation.

3. Thermal runaway and fire -If a BM suddenly goes into thermal runaway this innovation not only puts out the fire and removes with the smoke from the battery pack, but also removes the burnt out BM immediately from the circuit, so that the battery pack can keep functioning albeit at reduced capacity.

(2(),. s the:(iver(111M9 in this disclosure are

1. make the battery pack safe i.e. protection from exposure to high voltages in the event of accident or repair; 2. make the battery pack highly reliable; in terms of expected life of the battery pack and continuity of service.

Brie thont Drawings * Figure 7 -shows the schematic circuit diagram of overall system of relays switching ON/OFF the circuit of BMs * Figure 2.1 -shows the battery pack controller and the battery pack * Figure 2.2 -shows the relays, the BMs and inside of the battery pack Detailed description of preferred emboddnent, and now it is manufactured The inventions will be explained through preferred examples of Battery pack controller (140).

nattery pack contraler (140) The aim of this invention is to design an apparatus of a battery pack controller, which provides: a. safety from high voltage in the event of an accident or repair or during assembly; b. extend the life of the battery pack by proactively removing the failed or about to fail BMs from the electrical series circuit; c. In the event of thermal runaway, put out the fire, deal with the smoke, deal with the burnt out module so that it's not a threat to the functioning of the battery pack.

In this disclosure, Battery module (BM) (200) is designed to hold plurality of rechargeable batteries and capacitors, arranged in one or more groups. BMs are fully submerged in dielectric liquid inside the battery pack.

In this disclosure, the dielectric liquid is a thermally conductive but electrically insulative liquid. E.g. flurocarbons.

In this embodiment the battery pack has a configuration of 128564P, with 128 battery modules (BMs) connected in series, and each BM has a configuration of 62 batteries connected in parallel and 2 capacitors in parallel.

In this particular embodiment BM has 62 cylindrical lithium-ion (Li-ion) rechargeable batteries (220) and 2 capacitors. In another embodiment it could be any other chemistry; in the shape of cylinder, tower, pouch or prismatic or any other shape. Further the batteries could be of high energy density. In this disclosure all these rechargeable batteries (220) of different chemistries and shapes are referred to as Batteries (220) in plural and Battery in singular. In this particular embodiment BM has 2 Electric double layer capacitors (EDLC) cylindrical capacitors, also called supercapacitors. In another embodiment these capacitors could be Asymmetric Electrochemical Double Layer Capacitor (AEDLC), Lithium Ion capacitors, or graphene supercapacitors. In this disclosure all capacitors of different electrochemical, chemistries and shapes are referred to as capacitors in plural and capacitor in singular. In another embodiment there could be any number of batteries (220) and any number of capacitors (220) in a BM.

In this disclosure, the combination of batteries and capacitors is optional. The BM(200) can be created just with batteries. The BM(200) can also be created just with capacitors.

In another embodiment a group of batteries and a group of capacitors can be arranged together inside a battery pack(100), without the mechanical casing of a BM. Each such group of batteries and capacitors is considered as one BM. If one or more such groups are connected in series or parallel, then multiple BMs are considered to be connected in series and parallel.

In another embodiment large batteries/capacitors can be horizontally and/or vertically arranged, using one or more mesh like structures, without using multiple BMs. In such an embodiment the electrical connections to the batteries/capacitors can be embedded inside the mesh or laid above or below the mesh. In further embodiment part of the wiring can be based on radio signals, especially the control signals. For this disclosure each such mesh like structure is considered as one BM. In this disclosure, if multiple layers of mesh like are structures are stacked, each layer is considered as one BM and vertical layers of mesh are considered as vertically stacked BMs.

Figure 7 is the electrical schematic diagram of BMs connected in series inside the battery pack (100). It shows a relay switch (133) which has two positions, in ON position a set of 4 BMs is included into the high voltage series circuit and in OFF position the group of 4 BMs is taken out of the series circuit. In this embodiment a relay is used for each set of 4 BMs In this embodiment of 128564P configuration of the battery pack, 128 BMs are connected in series with each BM (200) having 62 batteries and 2 capacitors. As shown in figure 2.1, there are 4 rows of 8 BMs horizontally laid and 4 BMs are vertically stacked resulting in 128 (8x4x4) connected in series. As shown in figure 2.2, for each set of 4 BMs there is one relay switch (133), installed at the top of the PCB (131). However in another embodiment e.g. configuration of 1605256P; has 160 BMs connected in series, with 248 batteries and 8 capacitors in each BM; 16 BMs laid horizontally and 10 vertically (16BMx10BM mechanical configuration). In such an embodiment 1 relay could be used for 10 vertically stacked BMs. Thus relay switch can take out 10 BMs each with 256P batteries/capacitors, from the series circuit.

Figure 7 also shows that the relay switches (133) are controlled by battery pack controller (140).

In this embodiment the battery pack controller is installed inside the battery pack, however in another embodiment it can be installed outside the battery pack(100). In another embodiment only part of the battery pack controller can be installed inside the battery and part outside the battery pack. In this disclosure the battery pack controller installed either inside the battery pack or outside the battery pack or part inside and part outside the battery pack, is termed as battery pack controller.

As shown in the Figure 7, the relays (133) can completely switch off the serial circuit inside the container (101) such that system (max voltage at any point within the battery pack) voltage falls to 4*4.2V = 16.8v which complies with SELV (Safety extra low voltage) level.

There are various standards of SELV, the voltage of 60v is considered as SELV in this disclosure. In this disclosure relay switch (133) means a switch e.g. FET, MOSFET etc. When the battery pack controller reads a trigger from the vehicle control unit (VCU) or any other control unit of an application e.g. vehicle is switched off or vehicle is involved in an accident, trigger of flooding, trigger of fire or trigger from a manual switch, trigger of being transported in carrier/ship/lorry, the battery pack controller puts all the relay switches in OFF position. As shown in Figure 7, all the BMs are connected through a series of relay switches, through group of 4 BMs, hence when the vehicle is switched off or involved in an accident or any such trigger, all the BMs are taken out of the series circuit using the relays. In this embodiment the voltage inside the battery pack container drops to 4x4.2v= 16.8v which complies with SELV. However in another embodiment of configuration 160S256P, when a series of relays are installed, through a group of 10 BMs, the switched off voltage drops to 10*4.2= 42v, which also complies with SELV.

This innovation provides a safety to the occupants of the vehicle when it is involved in an accident; it also protects the emergency staff from being exposed to high voltages which can be as high as 800v for a large pack. It also allows the vehicle repair personal to be confident that they will not exposed to high voltages, especially when the vehicle is being repaired on a roadside by an emergency roadside recovery personnel. It also provides an extra layer of security to the vehicle from theft. It also provides safety from high voltage when vehicle is being transported on a vehicle carrier or a lorry or a ship. Switching off the circuit during transportation can be different from switching off the circuit when the vehicle is switched off, as during transportation vehicles need to be moved by the operators and can be switched on only to be pushed into a position without actually needing the HV power-hence the battery pack controller has to distinguish between the triggers from VCU. In this disclosure any such trigger which requires breaking of the circuit to below SELV trigger, with various priorities are considered to be a trigger from VCU or a control unit.

Figure 2.1 shows, in this embodiment Battery pack controller (140) is fitted inside a battery pack container (101). Figure 2.2 shows PCB (131) which connects to 4 vertically stacked BM (200) and a relay (133) which is installed at the end of the PCB (131) for a set of 4 BMs. In another embodiment the relay switches (133) can be attached anywhere on the PCB (131).

Battery pack controller's algorithm takes into battery's history of charging, history of SoC levels, impedance, SoH, thermal runaway etc and determines the failure of the batteries, and deems the BM as a failed BM. In this disclosure the failure of batteries or capacitors or BMs refers to Battery pack controller's declared failure. SoH and expected failure of the batteries etc is done by the operational centre, which does the remote monitoring of the vehicle (43). The operational requests the sensor and contextual data from the battery pack controller and frequently uploads the calculated data to the battery pack controller. Operational centre uses simulations to predict the failure and calculate SoH of the batteries/capacitors, which requires significant compute power.

In this embodiment, when a BM is deemed as a failed BM, the battery pack controller (140) automatically takes the group of 4 BMs of which the failed BM is a part, out of the series circuit by selectively setting that relay switch to OFF position. The battery pack controller takes the loss of 4 BMs into account when switching off a set of BMs. The battery pack controller alerts the user of limited battery pack capacity or request the user for confirmation in some cases to take the failed BMs out of the circuit, through its communication link (43). The relay of failed group of BMs permanently stays in OFF condition until the failed BM is replaced. The battery pack controller remembers to keep the failed BM relay in OFF position, while the other relays are switched ON or OFF as per the trigger messages from the VCU.

This innovation extends the life of the battery pack, and makes the battery pack highly reliable for critical applications. As within a battery pack not all the batteries age equally for various reasons. Capacity utilisation of the battery pack can be measured by the capacity of the weakest BM in series. Thus weak BMs can limit the usable capacity of the battery pack. This innovation can proactively take the weakest BM or BMs out of the series circuit, and increase the battery capacity without impacting the usage of the battery pack. This innovation can help electric vehicles become reliable.

Battery pack controllers also controls the fire, gases and pressure inside the container in the event of a fire inside the battery pack.

In figure 2.2 pressure sensor (129) measures the pressure inside the container (101). Battery pack controller (140) is electronically connected to the pressure sensor (129), and records the pressure inside the battery pack container (100) at all times.

In this disclosure electronic connection means when two devices communicate with each other through electronic (digital or analogue) signals e.g. electronic connection between battery pack controller (140) and a sensor or electronic connection between battery pack controller(140) and battery charge controller (240).

Battery pack controller (140) is electronically connected to a gas solenoid (not shown). Battery pack controller (140), opens the gas solenoid to release the pressure inside the container (101) if the pressure inside the container (101) is higher than preset level, and also closes the solenoid valve after the pressure reaches a preset level.

Liquid level sensors (not shown) measure the level of the dielectric liquid inside the container (101). Battery pack controller (140), electronically connected to the liquid level sensor, monitors the dielectric liquid level inside the container (101) using these sensors, and alerts the user of the battery pack to top the dielectric liquid if the level of the dielectric liquid inside the container (101) is lower than the preset level.

In the event of fire, as the batteries/capacitors are submerged in dielectric liquid, the fire extinguishing properties of the dielectric liquid puts out the fire. The gas solenoid releases the gases/smoke from the fire from the battery pack, the gas solenoid also releases the pressure build up inside the battery pack due to smoke.

Further innovation is that the battery pack controller, in the event of thermal runaway or fire puts out the fire using the fire extinguishing properties of the dielectric liquid as well as releases the smoke from the battery pack. Further innovation is that the battery pack controller immediately removes the burnt out BM out of the series circuit so that battery pack can continue to be used. This lets the user reach home with limited capacity of the battery pack, until the battery pack can be repaired/replaced.

Battery pack controller is also electronically connected to the vehicle control unit which can provide trigger instructions to the controller regarding its operations e.g. vehicle is switched off or involved in an accident etc. In another embodiment two or more Battery packs can be installed in an electric vehicle e.g. in a train carriage. These battery packs can be independently controlled by the vehicle control unit or all the battery packs can be electronically chained, such that the vehicle control unit can manage all the battery packs by electronically connecting to battery pack controller of just one of the battery packs which acts as a master controller to other pack's battery pack controllers (140) which act as slave/s.

Battery pack controller (140) also acts as a master controller of the following charging and discharging circuits: a. Energy charging split circuit -this circuit switches the charging current between, high voltage DC supply, AC supply and regenerative energy.; b. Energy discharging split circuit -This circuit acts like a mixer of batteries and capacitors current and is controlled by the energy management algorithm of battery pack controller (140); Battery pack controller (140) is made up of hardware and software. Battery pack controller (140) also has two key algorithms: a. Balanced charging algorithm -balanced charging algorithm calculates the Balanced SoC for said group of batteries; preferably and calculates Balanced voltage for said group of capacitors;; b. Energy management algorithm -The energy management algorithm of battery pack controller (140), calculates the optimal mix of battery current and capacitor current to meet the peak current demand from a given BM/battery pack.

Battery pack controller (140) also consists of a memory card which records battery pack's manufacturing details and battery pack's history of charging and discharging and temperatures e.g. number of charge cycles; number of times temperature exceeded maximum limit and the respective temperatures; number of times limits on current been reached and the respective currents; no of times battery pack fallen below the minimum required charge and the respective charge etc; this memory card can be used to settle warranty claims.

Example of *intended

* Power unit for large electric vehicles e.g. trucks, SUVs, vans, trains * Backup power unit for hospitals, data centres and industrial units * Energy storage unit for solar panels Glossary Dielectric liquid -is a dielectric material (thermally conductive but electrically insulative) in a liquid state. E.g. flurocarbons Multi layer faced/sided PCB -printed circuit board with multi layers auxiliary low voltage batteries Smartphone -personally held devices like phone or tablets e.g. iPhone or Samsung Vehicle control system -control system of the vehicle

Claims

ilattkqy p;:ck:r.ontrz.dthr 1. The battery pack controller, is an apparatus designed as a master controller of a battery pack, comprises: a. an algorithm that reads the triggers/messages from vehicle control unit or any control unit of an application and makes logic decisions e.g. vehicle is switched off/on, vehicle is in a crash situation etc b. controls the relays/power switches, to automatically break the circuit inside the battery pack such that system voltage inside the battery pack is less than SELV level e.g. when vehicle is switched off, or when vehicle in a crash situation etc; c. an algorithm that continuously/regularly calculates the capacity utilisation of a BM and compares with the installed capacity of the said BM after taking the SoH, impedance, thermal runaway etc of the batteries/capacitors of said BM into account, and makes the logic decision to declare a BM as a failed BM; d. controls the relays/power switches to automatically take the failed BM or group containing the failed BMs out of the electrical circuit inside the battery pack, such that the remaining BMs can continue to function.
2. The battery pack controller of claim 1 preferably also takes the BM out of the series circuit if the capacity utilisation of the battery pack increases by taking the BM and the group of BMs of which that BM is a part, out of the series circuit.
3. The battery pack controller of claim 1 preferably also requests user of the battery pack for a confirmation or informs the user, when it takes out one or more failed BMs out of the series circuit.
4. The battery pack controller of claim 1 remembers to keep the relay which takes the failed BMs out of the electrical series circuit, to be in permanently switched off position until the failed BM or BMs are replaced.
5. The battery pack controller of claim 1 also consists of proactive removal of a weak BM from the electrical series circuit, to avoid the reaching the point of thermal runaway.
6. The battery pack controller of claim 1 also instructs the charging algorithm such that failed BMs which are taken out of the circuit are not charged any longer.
7. The battery pack controller of claim 1 preferably also instructs the discharging circuit such that remaining BMs are not stressed due to reduced number of BMs in the battery pack.
8. The relays/power switches of claim 1 are preferably powered by auxiliary battery, such that if the auxiliary battery is disconnected all or some of the relays/power switches are switched OFF, and the system voltage falls below the SELV level.
9. The battery pack controller of claim 1 preferably also consists of all BMs are fully submerged in dielectric liquid which also acts as fire extinguisher incase of a fire or thermal runaway.
10. The battery pack controller of claim 1 is also electronically connected to the temperature sensors inside the said battery pack e.g. to check if there is any thermal runaway;
11. The battery pack controller of claim 1 is preferably also electronically connected to the pressure sensors inside the said battery pack to record the pressure inside the battery pack container e.g. to measure pressure build up due to gases from thermal runaway.
12. The battery pack controller of claim 1 preferably also controls the gas solenoid valve or any pressure control device to automatically open the valve/device e.g. to release the gases incase of thermal runaway and release the build up of pressure inside the container.
13. The battery pack controller of claim 1 is preferably also electronically connected to the liquid level sensors inside the said battery pack container and warns the users if the level of the dielectric liquid drops below a preset level e.g. to check if the batteries are no longer submerged in dielectric liquid as it can lead to batteries overheating.
14. The battery pack controller of claim 1 preferably also controls the gas solenoid valve/s to open the solenoid valve for topping up of the dielectric liquid inside the container e.g. to protect the safe operations of the battery pack.
15. The battery pack controller of claim 1 can be installed inside the battery pack or outside the battery pack, is made up of purpose built/configured hardware and software: a. the hardware preferably consists of a motherboard with microprocessor, hard drive and memory chips, microcontrollers, and the electronic communication circuitry; b. the software preferably which provides the decisions logic and stores the date e.g. CAN or Ethernet communications; stores the reference data of safe limits of the said batteries and said dielectric liquid; stores the history of charging and discharging, stores the user preferences etc.
16. The battery pack controller of claim 1 preferably also consists of a memory card which records battery pack's history of usage e.g. number of charge cycles; number of times temperature exceeded maximum limit and the respective temperatures; number of times limits on current been reached and the respective currents; no of times battery pack fallen below the minimum required charge and the respective charge etc; this memory card can preferably be used to settle warranty claims.
17. The battery pack controller of claim 1, is preferably also electronically connected to the vehicle control unit and/or motor controller of the electric vehicle using CAN or Ethernet network, to: a. preferably provide information e.g. health of the batteries/BMs, status of charge left in the battery pack, warning notifications in the event of thermal runaway etc; b. preferably take instructions e.g. vehicle is in an accident situation trigger, isolate the power supply etc.
18. The battery pack controller of claim 1 of one battery pack acts as a master of two or more battery packs when two or more battery packs are connected to supply large power, such that the master battery pack controller controls the relays/power switches of all the slave battery packs,.
19. The battery pack controller of claim 1 is preferably also electronically connected to external smartphone based app to provide information and take instructions, to: a. provide information for remote monitoring e.g. health of the battery, status of charge left in the battery pack, number of cycles of charging, warning notifications in the event of failed BMs, thermal runaway etc; b. and take instructions e.g.to the battery pack needs service/BMs replacement, isolate the power supply etc.
20. The battery pack controller of claim 1 is preferably also electronically connected to external operational centre e.g. through Wi-H, to: a. provide detailed information on request for remote monitoring e.g. contextual data, sensor data, warning notifications etc; b. and receive information and instructions which are specific to the battery pack e.g. SoH of the batteries/capacitors, Failure of the batteries/capacitors, prediction of failure, need service etc. A::nethod provkfingalety awl rthabth ty to a bath try po.ck
21. A method of providing safety and reliability to a battery pack, comprising: a. an algorithm reading the triggers/messages from vehicle control unit or any control unit of an application and making logic decisions e.g. vehicle is switched off/on, vehicle is in a crash situation etc b. controlling the relays/power switches, to automatically break the circuit inside the battery pack such that system voltage inside the battery pack is less than SELV level e.g. when vehicle is switched off, or when vehicle in a crash situation etc; c. an algorithm continuously/regularly calculating the capacity utilisation of a BM and comparing with the installed capacity of the said BM after taking the SoH, impedance, thermal runaway etc of the batteries/capacitors of said BM into account, and making the logic decision to declare a BM as a failed BM; d. controlling the relays/power switches to automatically take the failed BM or group containing the failed BMs out of the electrical circuit inside the battery pack, such that the remaining BMs can continue to function.
22. The battery pack controller of claim 20 also involves the said power switches defaulting to an OFF position (circuit is broken), unless switch ON (circuit is complete) by the said battery pack controller.
23. The battery pack controller of claim 20 also involves disconnecting the auxiliary battery's connection to the battery pack before any repair is carried out to the battery pack or high voltage drive train.
24. The battery pack controller of claim 20 preferably switching off all the relays upon receiving a trigger from the user or vehicle control unit..A method of remoteMbrwMg the battery pa,ck
25. A method of remote monitoring of battery pack of claim 1, by a remote operational centre, comprising: a. Battery pack controller providing detailed information on request e.g. contextual data, sensor data, warning notifications etc; b. Operational centre using simulation methods for calculating the SoH of batteries/capacitors, predicting failure of BMs, calculating logic to extend the life of BMs; c. Battery pack controller receiving information, and instructions which are specific to the each battery pack e.g. SoH of batteries/capacitors, Failure of the BMs, prediction of failure, need service etc.