HK1147851B

HK1147851B - Fault tolerant modular battery management system

Info

Publication number: HK1147851B
Application number: HK11101205.6A
Authority: HK
Inventors: 周克翰
Original assignee: 周克翰
Priority date: 2009-06-15
Filing date: 2011-02-08
Publication date: 2013-10-25

Description

Fault-tolerant modular battery management system

Technical Field

The present invention relates to a battery management system of an electric vehicle or a hybrid electric vehicle, and more particularly, to a fault-tolerant Modular Battery Management System (MBMS) capable of supporting a critical load and having a high power output capability.

Background

The electrical power requirements of Electric Vehicles (EV) or Hybrid Electric Vehicles (HEV) are both very high. During vehicle launch/run mode, and run/brake/internal and external charging modes, the battery undergoes discharge and charge cycles, respectively. Management of battery state of health, battery state of charge, and battery temperature is critical in electric or hybrid electric vehicle applications when power cannot be interrupted while driving. Also, different battery management systems may be required due to different battery types, voltages, and power requirements of different types of electric or hybrid electric vehicles. Thus, due to differences in battery type, power requirements, and vehicle operating voltage, the battery power system framework design of one vehicle may be completely different from the design of another vehicle. Sometimes the charging and replacement time of the battery pack causes a temporary interruption to the user. A failed battery pack may cause immediate failure of the electric vehicle or the hybrid electric vehicle.

Conventionally, Battery packs (or Battery cells) are connected in series to form a Battery Pack Assembly (BPA) to provide high voltage or high current to an electric vehicle or hybrid electric vehicle motor or other auxiliary system. Since the battery packs or cells are connected in series, charge and discharge currents will flow through each battery pack (or cell) simultaneously. This may cause a balancing problem due to a difference in characteristics of the respective battery packs (or battery cells). Due to the series connection between the batteries, the conventional battery management system detects the state of charge, the state of health, and the battery temperature of each battery pack (battery cell) through a complicated battery management design. Depending ON the detected battery pack (or cell) condition, the respective battery pack (or cell) will be switched-ON or switched-OFF (OFF) to the battery pack (or cell) connected in series. As a result, the BPA output voltage fluctuates. This can lead to instability problems with the motor drive and associated circuitry. Thus, a DC/DC converter would be used to convert the fluctuating BPA output voltage to a stable voltage source for the motor driver and associated circuitry. However, the DC/DC converter must operate under conditions of high voltage and high current. High power consumption in DC/DC converters generally reduces the reliability of the overall system. Once the DC/DC converter fails, the entire system is shut down. Furthermore, the battery pack combined (BPA) power cannot be easily increased or decreased to meet different load requirements. Furthermore, the failed battery pack or cell cannot be replaced until the Battery Pack Assembly (BPA) is removed from the vehicle.

Accordingly, there is a need in the art for an improved battery management system having fault tolerant features to address the problems of battery imbalance and failed cells. In addition, it is desirable to be able to implement other features such as power bus voltage, power output capability, and variability in the number of batteries.

The above description of the background art is provided to aid in understanding a fault tolerant modular battery management system, but is not admitted to describe or constitute prior art to the fault tolerant modular battery management system disclosed in this application.

Disclosure of Invention

The present invention relates to a modular battery management system for managing a plurality of batteries and driving a load. In one aspect, the system comprises: a plurality of battery management control modules; the battery management control module is connected with the battery management control module and the battery management control module respectively; and a plurality of energy storage modules, which are respectively connected with the bidirectional voltage converter modules in parallel and are connected with the load. The bi-directional voltage converter module is configured to transfer electrical energy from the battery to a load or from the energy storage module to the battery. The battery management control module is configured to execute a predetermined program based on the state information of each battery and control the bidirectional voltage converter module.

The energy storage module may be a capacitor, a super capacitor (supercapacitor), an ultra capacitor (ultra capacitor), a flywheel (flywheel) or any form of recyclable electrical energy storage element.

The bi-directional voltage converter module may be configured to transfer electrical energy from the energy storage module to the battery to charge the battery when the voltage across the energy storage module exceeds a predetermined value.

The bidirectional voltage converter module is connected with the battery through a plurality of first switches respectively. The energy storage module is connected in parallel with the bidirectional voltage converter module through a plurality of second switches respectively. The load is connected to the energy storage module through a third switch. The plurality of first switches, the plurality of second switches, and the third switch are controlled by the battery management control module.

The battery management control module may be configured to simultaneously disable one of the plurality of first switches and the bi-directional voltage converter module connected to the switch.

The modular battery management system also comprises a plurality of battery state monitoring modules which are respectively connected with the batteries and the battery management control module, are configured to monitor the state of each battery and send the state information of each battery to the battery management control module. The battery state monitoring module and the bidirectional voltage converter module are connected with the battery management control module through a control bus.

When one battery management control module stops working normally, other battery management control modules can be configured to restore the functions of the battery management control modules.

The battery management control module may be configured to adjust an output voltage level of the bi-directional voltage converter module based on a user's instructions.

Drawings

FIG. 1 is a schematic system block diagram of a fault tolerant modular battery management system according to an embodiment of the present invention.

Fig. 2 is a schematic circuit diagram of the fault tolerant modular battery management system shown in fig. 1.

Detailed Description

Reference will now be made in detail to the preferred embodiments of the fault tolerant modular battery management system disclosed in the present patent application, examples of which are set forth in the following detailed description. Exemplary embodiments of the fault tolerant modular battery management system of the present patent application are described in detail, although it will be apparent to those skilled in the art that certain features that are not particularly important to an understanding of the fault tolerant modular battery management system may not be shown for the sake of brevity.

Further, it is to be understood that the fault tolerant modular battery management system disclosed herein is not limited to the precise embodiments described below, and that various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the protection. For example, elements and/or features of different exemplary embodiments may be combined with each other and/or substituted for each other within the scope of this disclosure.

FIG. 1 is a schematic system block diagram of a fault tolerant modular battery management system according to an embodiment of the present invention. Fig. 2 is a schematic circuit diagram of the fault tolerant modular battery management system shown in fig. 1. Referring to fig. 1 and 2, the fault tolerant modular battery management system includes a plurality of battery state monitoring modules 201, 202, … …, 20n, a plurality of bidirectional DC/DC converter modules 401, 402, … …, 40n, a plurality of energy storage modules 1401, 1402, … …, 140n, a plurality of battery management control modules 1201, 1202, … …, 120n, and a plurality of battery packs (or cells) 101, 102, … …, 10 n. Each battery pack (or cell), e.g., 101, 102, … …, 10n, is connected to a dedicated battery condition monitoring module and then to a bi-directional DC/DC converter (e.g., 401, 402, … …, 40n) via a plurality of switches 301, 302, … …, 30 n. This combination is referred to as a Battery Power Converter Module (BPCM). Each battery pack (or cell) is isolated from the other battery packs (or cells). This arrangement is different from the batteries connected in series in a conventional battery management system. The bidirectional DC/DC converter outputs are connected in parallel to increase the overall current capacity to provide the load current.

The battery pack may include various types of batteries including, but not limited to, lead-acid batteries, nickel metal hydride batteries, nickel cadmium batteries, lithium ion batteries, lithium polymer batteries, Na/NiCl with zero emissions pollution₂A battery, a NiZn battery, a lithium ion phosphoric acid battery, a ferroelectric battery, or any form of rechargeable electrical energy storage element.

As used herein, an Energy Storage (ES) module refers to an electrical energy storage element, including but not limited to a capacitor, a super capacitor, an ultra capacitor, a flywheel, or any form of recyclable electrical energy storage element. In this embodiment, referring to fig. 1, the energy storage modules are capacitors 1401, 1402, … …, 140n, connected to all bidirectional DC/DC converter modules through switches 501, … …, 50n, respectively.

As used herein, a bidirectional DC/DC converter module refers to an electrical configuration that may be used to charge energy from an Energy Storage (ES) module to a battery pack (or battery cell), or may be used to convert energy from a battery pack (or battery cell) to an Energy Storage (ES) module and a load connected to the energy storage module.

The connection between the bi-directional DC/DC converter output, the energy storage module and the load is referred to as the power bus. Current may be drawn into the load from the power bus. The load current will be shared by the bi-directional DC/DC converter output. The bi-directional DC/DC converter module may be of the isolated or non-isolated type, configured to convert the battery voltage to a required load voltage level. Thus, the load voltage is determined by the bi-directional DC/DC converter output voltage setting, rather than by the terminal voltage at the ends of the series connected batteries in conventional battery management systems. On the other hand, the bidirectional DC/DC converter module may charge the battery when sufficient energy is stored in the energy storage module. This may solve the problem of battery pack (or battery cell) imbalance in the conventional battery management system.

Battery Status Monitoring (BSM) modules 201, 202, … …, 20n are configured to provide battery status information to bidirectional DC/DC converter modules and Battery Management Control (BMC) modules 1201, 1202, … …, 120 n. The BMC module is configured to send control instructions to each Battery Power Converter Module (BPCM) in each operating state. For example, battery energy may be transferred from the battery to the power bus through the bi-directional DC/DC converter module, the battery may receive energy from the power bus through the bi-directional DC/DC converter module to charge the battery, the battery pack may be disabled and disconnected from the system, the battery may be removed from the system, and additional Battery Power Converter Modules (BPCM) may be added to the system. Meanwhile, depending on the algorithm implemented in the BMC program, some battery packs (or cells) may experience a discharge cycle (release power), some other batteries may experience a charge cycle (receive power), and still others may be disconnected from the system.

In a fully charged, unsafe or failed condition, the battery pack (cell) may be disconnected. If a battery is required to be removed from the system, the Battery Status Monitoring (BSM) module activates a release signal on the panel of the BSM module or activates a release signal to the BMC module. Under the control of the BMC module, a fully charged battery pack (cell) will be connected to the BPCM again. If the unsafe condition has cleared, the battery pack (or battery cell) that was once unsafe may be reconnected to the BPCM under the control of the BMC module.

The user may remove the battery from the modular battery management system. Similarly, a user may install a replacement battery into the modular battery management system and then activate the battery status monitoring module to notify the Battery Management Control (BMC) module via a Battery Management System (BMS) control bus. If a new battery is installed into the system, an additional BSM and a bidirectional DC/DC converter are required. The newly added or replaced battery will become part of a Modular Battery Management System (MBMS). With this technique, the user can increase the output of the modular battery management system (BPCM) by adding more Battery Power Converter Modules (BPCM), or can remove the battery pack (cell) from the system if necessary, all without significant design modifications to the system.

The power density of the battery may also increase the MBMS output power. The energy storage module is connected in parallel with the power bus. An energy storage module is an energy storage device that is charged with very high energy for a short period of time (e.g., 10 to 20 minutes). The energy storage module acts as a buffer for load inrush current and charging inrush current. When the voltage across the energy storage module exceeds a predetermined value, a Battery Management Control (BMC) module will command the bi-directional DC/DC converter module to charge the battery pack (or cell) through a BMC control bus. During charging, the ES module may be programmed to charge the battery packs individually, or to charge all of the battery packs at once, or to charge the battery packs randomly.

A Battery Management Control (BMC) module is a programmable unit that can be programmed to execute different algorithms to meet different vehicle/automobile requirements, such as different voltage levels, different battery pack (or cell) characteristics, and different load current requirements. Each BMC module is configured to detect the BMS control bus. Once a BMC module is in a failed state, other BMC modules will take over control without having to shut down the system.

In addition to fault tolerance features, the battery management control module may regulate the output voltage level of the bi-directional DC/DC converter module within a range to increase the torque of the motor (DC or AC) when additional torque is required to climb a hill. Therefore, it can be used as an Electric Torque Control (ETC).

Referring to fig. 1 and 2, the modular battery management system is based on a redundant layout. Thus, a detailed description of a first order Battery Power Converter Module (BPCM) is explained herein, which can be extended to cover systems up to n orders, where n is a positive integer.

The first Battery Power Converter Module (BPCM) stage includes a battery 101, the battery 101 having a positive polarity (+), a negative polarity (-), and a battery temperature signal 1101. The battery 101 is connected to the BSM module 201. The BSM 201 is a circuit that monitors battery conditions (e.g., state of charge, state of health, battery temperature, and charging condition/state) and feeds back information to a Battery Management System (BMS) control bus 1 through a signal path 601. The control signal 801 from the BSM control bus 1 will be used to display the battery operating status, which may be charging, discharging, dead battery, connected to the bi-directional DC/DC converter, or disconnected from the bi-directional DC/DC converter, through a status indicating device (e.g., an LED, display panel, or light). The output voltage of the battery 101 may be connected to the switch 301. The switch 301 is an electric switch for controlling the electrical connection between the BSM module 201 to the bidirectional DC/DC converter 401. The switch 301 is electrically controlled by a control signal 901, the control signal 901 being issued by a Battery Management Control (BMC) module 1201, 1202, … …, 120 n. During maintenance or repair, the switch 301 may be manually disabled. This is to avoid electrical hazards during maintenance or repair. Further, the signal 901 controls the on or off state of the bi-directional DC/DC converter 401. If the switch 301 is tightly energized by the signal 901 or manually switched, the bi-directional DC/DC converter 401 will be simultaneously disabled. During repair or maintenance, the control signal 1001 may disable the bi-directional DC/DC converter 401.

The temperature signal 1101 of the battery 101 is also connected to the bidirectional DC/DC converter 401. The bi-directional DC/DC converter module 401 will adjust the charging or discharging current according to the signal 1101. The current distribution between the different levels of bi-directional DC/DC converter modules is controlled by means of a current-share signal bus 6. The current-share signal bus 6 may be an analog or digital signal bus. The current-share signal bus 6 is bidirectional. The bi-directional DC/DC converter module 401 has a current share signal output that is bi-directional and connected to the current share signal bus 6. The current share signal outputs of the other bidirectional DC/DC converter modules are connected to a current share signal bus 6. The bi-directional DC/DC converter module 401 will adjust its output current according to the voltage level of the current-share signal bus 6 or a digital signal. The voltage level or digital information of the current-share signal bus 6 represents the average load current of each bidirectional DC/DC converter module. The bi-directional DC/DC converter 401 will communicate with the BSM control bus via the bi-directional bus 701. The output of the bi-directional DC/DC converter module is connected to the power bus 2. The power bus 2 connects the energy storage modules 1401 to 140n, the motor controller 3 (single or multiple), the internal charging circuit 4, and the external charging circuit 5. The energy storage modules 1404 to 140n are connected to the power supply bus 2 through switches 501 to 50n, respectively. The switches 501 to 50n are electrically controlled by the BMC module via control signals 1301 to 130n, respectively. The number of energy storage module starts is controlled by a program embedded in the BMC. Energy storage modules 1401 through 140n are configured to provide energy buffering during charging and discharging. In the charging mode, it will store energy from the external charging circuit, regenerative braking energy, and energy from the internal generator. This energy will be used to charge the batteries 101 to 10n through the bidirectional DC/DC converter modules 401 to 40n, respectively. In the discharge mode, it will provide power and energy to the motor controller and to the shock load condition so that the bi-directional DC/DC converter modules 401 to 40n are not overloaded. Battery Management Control (BMC) modules 1201 to 120n are connected and programmed in a redundant layout. If any one of the BMC modules fails, the other BMC modules will seamlessly restore the functionality of the failed module. The BMC module is connected to the BMS control bus 1 through bidirectional communication buses 1501 to 150 n.

The switches 301 to 30n, 7, 8, 9 are controlled by the battery management control modules 1201 to 120n through the BMS control bus. When the vehicle is parked, the switches 301 to 30n, 7, 8, 9 are opened (open circuit). When the vehicle is started before the running state, the switches 7 and 8 are closed (connected). If no battery charging is required, the switch 8 will be open (open circuit). When external charging is required, switch 9 will be closed (on) and switches 7 and 8 will be open (open). This is to prevent an electric power overload from being generated to the motor controller 3 and the internal generator 4 during external charging. If the motor controller or generator is designed to withstand this load capacity, switches 7 and 8 can be closed (connected).

Referring to fig. 2, in this circuit implementation, the battery condition monitoring module combinations 201, 202, … …, 20n form an integral part of the system. The bus a connector is connected to the BMS control bus. The connect/disconnect switch and the bidirectional DC/DC converter module form a bidirectional DC/DC converter combination, which is an integral part of the system. The bus B connector is connected to the BMS control bus. The battery state control module combination and the bidirectional DC/DC converter combination are connected to the BMS control bus. The output of the bi-directional DC/DC converter combination and the DC power bus 2 are connected in parallel with each other. Similarly, the battery management control modules are connected to the BMS control bus by respective bus a and bus B connectors. The bus C connector provides an interface between the vehicle signal interface 10 and the battery management control modules (1201, 120n) through the BMS control bus. The vehicle signal interface 10 is the control interface for the energy storage module, the internal charging circuit and the external charging circuit.

In the foregoing embodiment, the fault tolerant modular battery management system is characterized by multiple redundancies at all module levels. These redundant features allow for simultaneous maintenance operations and provide multiple levels of fault tolerance. Thus, the modular battery management system has improved reliability and usability. Furthermore, all levels of modules can be economically manufactured due to the modular design framework.

In the foregoing embodiments, individual cells or modules may be removed from, or added to, MBMS without interrupting system availability. The battery pack (or cell) may be removed from, or added to, the MBMS without interrupting system availability. The BSM module can be removed from or added to the MBMS without interrupting system availability. The bi-directional DC/DC converter module can be removed from, or added to, MBMS without interrupting system availability. The energy storage module may be removed from, or added to, the MBMS without interrupting system availability. The BMC module may be removed from MBMS or added to MBMS without interrupting system availability.

In the foregoing embodiments, the MBMS provides a framework for EV or HEV or battery operated machines/devices. This framework can be used for different battery types, power bus voltages and output power requirements. In certain applications, the BSM and the bidirectional DC/DC converter modules may be combined into a single module (or unit). The battery packs (or cells) may be operated individually rather than in series in conventional systems. A fault tolerant modular battery management system solves the problem of battery pack (or cell) imbalance in conventional series connected battery packs. The output voltage to the power bus is determined by the bi-directional DC/DC converter module, rather than by the number of battery packs (or cells) in series. When some of the battery packs (or battery cells) cannot provide output power, the remaining battery packs (or battery cells) may provide limited output power at a rated voltage to operate the motor drive circuit. The output current is determined by the sum of the output currents of the respective bidirectional DC/DC converters.

In the foregoing embodiment, in the charging mode, the Energy Storage (ES) module is directly charged. This may speed up the charging cycle. The energy stored in the Energy Storage (ES) module is then charged to the battery pack (battery cell) through the bidirectional DC/DC converter module. The battery packs (or cells) in MBMS may be operated in different operation modes simultaneously. This includes battery discharge, battery charge, battery to MBMS connection, and battery to MBMS disconnection. In either the discharge or charge mode, the individual battery packs (or cells) may be programmed by the BMC module. In the vehicle drive mode, energy fed by internal generators, regenerative braking, and other power generation devices may charge some or all of the battery packs (or cells) through the Energy (ES) storage module and the bidirectional DC/DC converter module. This expands the range of vehicle travel distances. The battery life can be extended. By adding a Battery Power Converter Module (BPCM), the MBMS output capacity can be increased. The output capacity of the MBMS can be reduced by removing a battery pack (or battery cell), or a Battery Power Converter Module (BPCM). The MBMS output voltage may be adjusted by adjusting the bidirectional DC/DC converter output voltage. The control algorithm embedded in the BMC module may be programmed for individual battery pack charging, discharging, and disconnecting from MBMS. The control algorithm in the BMC module may be programmed for different battery characteristics, such as nickel metal hydride NiHM, lithium ion Li ion, lithium ion polymer, etc. The BMC module may display panel driver interaction information through the BMC. Battery charge and discharge status, remaining energy level, and battery maintenance information alerts may all be provided by the BMC display panel.

In the foregoing embodiments, the battery may be a combination of different types. For example, lead-acid and lithium batteries may be operated simultaneously in the system. The high power density characteristics of lithium batteries and the deep cycle discharge of lead acid batteries allow for a longer drive range.

While the present application has been illustrated and described with particular reference to several embodiments, it should be noted that various other changes or modifications could be made without departing from the scope of the invention.

Cross Reference to Related Applications

This application claims priority from U.S. provisional patent application No. 61/187,273 filed on 6/15/2009, the contents of which are incorporated herein by reference in their entirety.

Claims

1. A modular battery management system for managing a plurality of batteries and driving a load, the system comprising:

a plurality of battery management control modules;

the battery management control module is connected with the battery management control module and the battery management control module respectively; and

the energy storage modules are respectively connected with the bidirectional voltage converter modules in parallel and connected with the load;

wherein:

the bi-directional voltage converter module is configured to transfer electrical energy from the battery to a load or from the energy storage module to the battery; and is

The battery management control module is configured to execute a predetermined program based on the state information of each battery and control the bidirectional voltage converter module;

the bi-directional voltage converter module is configured to transfer electrical energy from the energy storage module to the battery to charge the battery when the voltage across the energy storage module exceeds a predetermined value.

2. The modular battery management system of claim 1, wherein the energy storage module is a recyclable electrical energy storage element.

3. The modular battery management system of claim 1, wherein the bi-directional voltage converter modules are each connected to the battery by a first plurality of switches, the energy storage modules are each connected in parallel to the bi-directional voltage converter modules by a second plurality of switches, the load is connected to the energy storage modules by a third switch, and the first plurality of switches, the second plurality of switches, and the third switch are controlled by the battery management control module.

4. The modular battery management system of claim 1, further comprising a plurality of battery status monitoring modules respectively coupled to the batteries, to the battery management control module, and configured to monitor the status of each battery and send status information of each battery to the battery management control module, wherein the battery status monitoring modules and the bi-directional voltage converter module are coupled to the battery management control module via a control bus.

5. The modular battery management system of claim 4, wherein when one battery management control module ceases to function properly, the other battery management control modules are configured to resume the function of the battery management control module.

6. The modular battery management system of claim 1, wherein the battery management control module is configured to adjust an output voltage level of a bi-directional voltage converter module based on a user's instructions.

7. The modular battery management system of claim 3, wherein the battery management control module is configured to disable one of the plurality of first switches and a bi-directional voltage converter module connected to the switch simultaneously.

8. A modular battery management system for managing a plurality of batteries and driving a load, the system comprising:

a plurality of battery management control modules;

the bidirectional voltage converter modules are respectively connected with the battery through a plurality of first switches and the battery management control module, and are connected in parallel; and

wherein:

The battery management control module is configured to execute a predetermined program based on state information of each battery and control the bidirectional voltage converter module and the plurality of first switches;

9. The modular battery management system of claim 8, wherein the energy storage module is a recyclable electrical energy storage element.

10. The modular battery management system of claim 8, wherein the battery management control module is configured to disable one of the plurality of first switches and a bi-directional voltage converter module connected to the switch simultaneously.

11. The modular battery management system of claim 8, further comprising a plurality of battery status monitoring modules respectively coupled to the batteries, to the battery management control module, and configured to monitor the status of each battery and send status information of each battery to the battery management control module, wherein the battery status monitoring modules and the bi-directional voltage converter module are coupled to the battery management control module via a control bus.

12. The modular battery management system of claim 11, wherein when one battery management control module ceases to function properly, the other battery management control modules are configured to resume the function of the battery management control module.

13. The modular battery management system of claim 8, wherein the battery management control module is configured to adjust an output voltage level of a bi-directional voltage converter module based on a user's instructions.

14. A modular battery management system for managing a plurality of batteries and driving a load, the system comprising:

a plurality of battery management control modules;

the battery state monitoring modules are respectively connected with the batteries, the battery management control module, the battery state monitoring modules and the battery management control module, are configured to monitor the state of each battery and send the state information of each battery to the battery management control module;

the energy storage modules are connected with the bidirectional voltage converter module in parallel through a plurality of second switches respectively and connected with a load through a third switch;

wherein:

The battery management control module is configured to execute a predetermined program based on the state information of each battery and control the bidirectional voltage converter module, the plurality of first switches, the plurality of second switches, and the third switch; and is

The battery state monitoring module and the bidirectional voltage converter module are connected with the battery management control module through a control bus;

15. The modular battery management system of claim 14, wherein the battery management control module is configured to disable one of the plurality of first switches and a bi-directional voltage converter module connected to the switch simultaneously.

16. The modular battery management system of claim 14, wherein the battery management control module is configured to adjust an output voltage level of a bi-directional voltage converter module based on a user's instructions.

17. The modular battery management system of claim 14, wherein the energy storage module is a recyclable electrical energy storage element.