Parallel control circuit and management mechanism for multi-cell battery system

Abstract

The invention discloses a battery parallel control circuit and a management mechanism for a multi-unit battery system. The battery parallel control circuit comprises a plurality of current sensing units used for sensing current of a plurality of battery units; the plurality of discharging control devices are coupled to the negative electrodes of the plurality of battery units and are respectively used for controlling the discharging of the plurality of battery units, and the plurality of charging control devices are coupled to the negative electrodes of the plurality of battery units and are respectively used for controlling the charging of the plurality of battery units; and the parallel control unit is used for sensing the voltage of the plurality of battery units from the negative electrodes of the plurality of battery units, so as to control the charging / discharging state of the plurality of battery units according to the voltage and current sensing results of the plurality of battery units.

Description

Technical Field

[0001] The present invention relates to battery management, and more particularly to a parallel control circuit and management mechanism for a multi-unit battery system. Background Art

[0002] Generally speaking, in order to increase the power of a battery-powered system, a battery-powered system is formed by connecting multiple battery cells in parallel. However, in a parallel architecture, the differences in characteristics between different battery cells may lead to problems such as circulating current. In order to avoid the generation of circulating current, it is usually necessary to perform individual voltage sensing and parallel management on the battery cells. Only when the voltage difference is within the allowable range can the battery cells be connected in parallel to implement multi-cell power supply. In view of this, the art needs an effective parallel management and control mechanism for multi-cell battery systems. Summary of the invention

[0003] In view of this, the present invention provides a battery parallel control circuit and management mechanism for a multi-cell battery system. The battery parallel control circuit and management mechanism of the present invention supports online hot swapping of individual battery cells, and performs parallel control of battery cells based on a single controller, avoiding communication between different controllers, so it has good response speed and ideal hardware cost. Furthermore, the present invention sets the charge and discharge control device on the low voltage side of the battery cell, so it can also simplify the complexity and hardware cost of the control device and related drive circuits.

[0004] An embodiment of the present invention provides a battery parallel control circuit for a multi-cell battery system. The multi-cell battery system selectively includes a first battery cell and a second battery cell. The parallel control circuit includes: a first current sensing unit and a second current sensing unit, a first discharge control device and a first charge control device, a second discharge control device and a second charge control device, and a parallel control unit. The first current sensing unit and the second current sensing unit are respectively coupled to the negative electrode of the first battery cell and the negative electrode of the second battery cell, and are used to sense the current of the first battery cell and the second battery cell respectively, thereby generating a first current sensing value and a second current sensing value. The first discharge control device and the first charge control device are coupled to the negative electrode of the first battery cell, and are used to control the discharge and charge of the first battery cell. The second discharge control device and the second charge control device are coupled to the negative electrode of the second battery cell, and are used to control the discharge and charge of the second battery cell. The parallel control unit is coupled to the first current sensing unit, the second current sensing unit, the first battery cell, and the second battery cell. The parallel control unit is used to sense the battery voltage from the negative electrode of the first battery cell and the negative electrode of the second battery cell, thereby generating a first voltage sensing value and a second voltage sensing value, and generating a plurality of control signals to control the first and second discharge control devices, and the first and second charge control devices, respectively, according to the first current sensing value, the second current sensing value, the first voltage sensing value and the second voltage sensing value. The multi-cell battery system can be coupled to a load or a charger, and the multi-cell battery system can discharge the load, or the charger can charge the multi-cell battery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 FIG. 4 is an application architecture diagram of a battery parallel control circuit according to an embodiment of the present invention.

[0006] Figure 2 FIG. 4 is a diagram showing the internal structure of a battery parallel control unit according to an embodiment of the present invention.

[0007]

Explanation of symbols

[0008] 1Battery System

[0009] 10First battery unit

[0010] 20 Second battery unit

[0011] 100 battery parallel control circuit

[0012] 111 first current sensing unit

[0013] 112 second current sensing unit

[0014] 120 parallel control unit

[0015] 131 first charging control device

[0016] 132 first discharge control device

[0017] 141 Second charging control device

[0018] 142 Second discharge control device

[0019] 200 loads / charger

[0020] D1, D2, D131, D132, D141, D142 diodes

[0021] S131, S132, S141, S142 switches

[0022] 121 control power supply

[0023] 122 Controller DETAILED DESCRIPTION

[0024] In the following text, many specific details are described to provide a thorough understanding of embodiments of the present invention to those skilled in the art. However, those skilled in the art will understand how to implement the present invention in the absence of one or more specific details, or using other methods, elements, materials, etc. In other cases, well-known structures, materials, or operations will not be shown or described in detail to avoid obscuring the core concepts of the present invention.

[0025] The reference to "an embodiment" in the specification means that the specific features, structures or characteristics described in the embodiment may be included in at least one embodiment of the present invention. Therefore, the "in an embodiment" that appears in various places in this specification does not necessarily mean the same embodiment. In addition, the aforementioned specific features, structures or characteristics can be combined in one or more embodiments in any suitable form.

[0026] Figure 1The battery parallel control circuit 100 is an application architecture diagram of the battery parallel control circuit of the present invention. As shown in the figure, the battery parallel control circuit 100 is used to control a battery system 1, which is composed of a plurality of batteries, including at least a hot-swappable first battery unit 10 and a second battery unit 20. The battery parallel control circuit 100 is used to parallel the first battery unit 10 and the second battery unit 20 and control charging and discharging. It includes a first current sensing unit 111, a second current sensing unit 112, a parallel control unit 120, a first charging control device 131, a first discharging control device 132, a second charging control device 141, and a second discharging control device 142. The first current sensing unit 111 and the second current sensing unit 112 are used to sense the magnitude and direction of the current flowing through the first battery unit 10 and the second battery unit 20, respectively, and generate current sensing values ​​I1 and I2 accordingly, so as to provide the parallel control unit 120 with the judgment of parallel connection and charge and discharge control. Furthermore, the parallel control unit 120 can also sense: the negative electrode voltage V1N of the first battery unit 10, the negative electrode voltage V2N of the second battery unit 20, the negative electrode voltage VLOADN of the load / charger 200, and the common positive terminal voltage VP, and then estimate the voltages of the battery units 10 and 20 to make a judgment on parallel connection and charge and discharge control, wherein the positive electrode of the first battery unit 10, the positive electrode of the second battery unit 20 and the positive electrode of the load / charger 200 are connected. The first discharge control device 131 and the second discharge control device 141 are respectively coupled to the negative electrodes of the first battery unit 10 and the second battery unit 20. The first charge control device 132 and the second charge control device 142 are respectively coupled to the negative electrode of the load / charger 200. The first discharge control device 131 is composed of a diode D131 and a switch SW131 connected in parallel, the first charge control device 132 is composed of a diode D132 and a switch SW132 connected in parallel, the second discharge control device 141 is composed of a diode D141 and a switch SW141 connected in parallel, and the second charge control device 142 is composed of a diode D142 and a switch SW142 connected in parallel. The first discharge control device 131 and the first charge control device 132 are used to control the charge and discharge of the first power supply unit 10, and the second discharge control device 141 and the second charge control device 142 are used to control the charge and discharge of the second power supply unit 20.

[0027] Figure 2Detailed internal structure diagram of the parallel control unit 120. The parallel control unit 120 includes a control power supply 121 and a controller 122. The control power supply 121 is used to power the controller 122. The positive terminal of the control power supply 121 is coupled to the common positive terminal VP, and the ground terminal is coupled to the anodes of the diodes D1 and D2, respectively. In addition, the cathodes of the diodes D1 and D2 are coupled to the negative electrode of the first battery cell 10 and the negative electrode of the second battery cell 20, respectively. When the voltage of the first battery cell 10 is higher, the diode D1 is turned on and the diode D2 is turned off, so that the first battery cell 10 provides electrical energy to the control power supply 121 to power the controller 122. Conversely, when the voltage of the second battery cell 20 is higher, the diode D2 is turned on and the diode D1 is turned off, so that the second battery cell 20 provides electrical energy to the control power supply 121 to power the controller 122. Furthermore, the controller 122 is used to generate control signals CD1, CC1, CD2 and CC2 according to the common positive terminal VP, the negative electrode voltage V1N of the first battery unit 10, the negative electrode voltage V2N of the second battery unit 20, and the current sensing values ​​I1 and I2. The control signals CD1, CC1, CD2 and CC2 are used to control the switches SW131, SW132, SW141 and SW142 in the first discharge control device 131, the first charge control device 132, the second discharge control device 141 and the second charge control device 142, respectively.

[0028] First, the parallel control unit 120 can determine whether a load or charger is connected to the battery system 1 by sensing the negative electrode voltage VLOADN of the load / charger 200. When the negative electrode voltage VLOADN of the load / charger 200 is greater than zero, it is determined that the load / charger 200 connected to the battery system 1 is substantially a load. In addition, when the parallel control unit 120 senses a voltage drop in a first voltage sensing value (e.g., the negative electrode voltage V1N of the first battery cell 10), the parallel control unit 120 determines that the battery system 1 includes the first battery cell 10 (i.e., the first battery cell 10 is installed in the battery system 1). At this time, the parallel control unit 120 turns on the switch SW131 in the first discharge control device 131 through the control signal CD1, so that the first battery cell 10 discharges the load 200. Furthermore, the parallel control unit 120 will perform further control based on the size of the current sensing value I1 (i.e., the size of the discharge current), wherein if the current sensing value I1 is greater than the discharge current setting value DCTH, the switch SW132 in the first charging control device 132 will be turned on through the control signal CC1, thereby reducing the conduction loss caused by the discharge of the first battery unit 10 by the first charging control device 132.

[0029] On the other hand, when the parallel control unit 120 senses that the negative electrode voltage VLOADN of the load / charger 200 is less than zero, it is determined that the load / charger 200 connected to the battery system 1 is substantially a charger. And, when the parallel control unit 120 senses that the first voltage sensing value (the negative electrode voltage V1N of the first battery cell 10) has a voltage drop, it is determined that the battery system 1 includes the first battery cell 10. At this time, the parallel control unit 120 will issue a control signal CC1 to turn on the switch SW132 in the first charging control device 132, so that the charger 200 charges the first battery cell 10. Furthermore, if the parallel control unit 120 senses that the current sensing value I1 (i.e., the magnitude of the charging current) is less than the charging current setting value CCTH (less than zero), the switch SW131 in the first discharge control device 131 will be turned on through the control signal CD1, thereby reducing the conduction loss caused by the first discharge control device 131 charging the first battery cell 10.

[0030] During the discharge of the first battery unit 10, when the parallel control unit 120 senses a voltage drop in a second voltage sensing value (e.g., the negative electrode voltage V2N of the second battery unit 20), the parallel control unit 120 determines that the battery system 1 includes the second battery unit 20 (i.e., the second battery unit 20 is installed in the battery system 1). At this time, the magnitude of the negative electrode voltage V1N of the first battery unit 10 and the negative electrode voltage V2N of the second battery unit 20 is further determined. If the negative electrode voltage V1N is less than the negative electrode voltage V2N, or the difference between the two is very close, the second battery unit 20 is allowed to discharge the load 200, and the parallel control unit 120 turns on the switch SW141 in the second discharge control device 141 through the control signal CD2, so that the second battery unit 20 is connected in parallel with the first battery unit 10 to discharge the load 200 together.

[0031] Furthermore, if the voltage of the second battery unit 20 is lower than the voltage of the first battery unit 10, the diode D142 in the second charging control device 142 will be cut off, so that the second battery unit 20 cannot output current. At this time, the first battery unit 10 will continue to discharge the load 200, and its voltage will gradually decrease until it is lower than the voltage of the second battery unit 20, and the second battery unit 20 can output current. When the current sensing value I2 is greater than the discharge current setting value DCTH, the parallel control unit 120 will turn on the switch SW142 in the second charging control device 142 through the control signal CC2, thereby reducing the conduction loss caused by the discharge of the second battery unit 20 by the second charging control device 142.

[0032] If the negative electrode voltage V1N is greater than the negative electrode voltage V2N, it means that the voltage of the second battery unit 20 is higher than the voltage of the first battery unit 10, and the parallel control unit 120 will turn off the switch SW132 in the first charging control device 132 through the control signal CC1, and turn on the switch SW141 in the second discharge control device 141 through the control signal CD2. At this time, if the voltage of the first battery unit 10 (or the second battery unit 20) is lower, the first battery unit 10 (or the second battery unit 20) will stop outputting current, and the second battery unit 20 (or the first battery unit 10) will output current instead. In addition, when the current sensing value I2 (or the current sensing value I1) is greater than the discharge current setting value DCTH, the parallel control unit 120 will turn on the switch SW142 (or the switch SW132) in the second charging control device 142 (or the first charging control device 132) through the control signal CC2 (or the control signal CC1), thereby reducing the conduction loss of the second charging control device 142 (or the first charging control device 132) caused by the battery discharge.

[0033] During the discharge period, if the difference between the negative electrode voltage V1N and the negative electrode voltage V2N is less than the voltage difference setting value VDTH, it means that the voltage difference between the first battery unit 10 and the second battery unit 20 is not large enough to cause the reverse current problem. At this time, the parallel control unit 120 will control the switches SW132 and SW142 in the first charging control device 132 and the second charging control device 142 through the control signals CC1 and CC2, respectively, so that the first battery unit 10 and the second battery unit 20 are completely connected in parallel. If during the fully parallel discharge period, when the current sensing units 111 and 112 sense the reverse current (i.e., the charging current), and the magnitude of the reverse current exceeds the reverse current setting value ICTH, and the currents of the first battery unit 10 and the second battery unit 20 are also reverse currents, it is a normal situation of regenerative charging of the load (i.e., the load 200 is the power system in the electric vehicle, and the electric energy generated by it during braking can charge the battery system 1), and no processing is required. On the contrary, if one of the currents of the first battery unit 10 and the second battery unit 20 is a forward current (i.e., a discharge current) and the other is a reverse current (and the magnitude exceeds the reverse current setting value ICTH), the parallel control unit 120 will use a control signal to turn off the switch (e.g., switch SW132 or switch SW142) in the charging control device (e.g., the first charging control device 132 or the second charging control device 142) corresponding to the battery unit with the reverse current. In this way, the circulating charging of the battery unit with the reverse current can be stopped.

[0034] During charging, when the first battery unit 10 or the second battery unit 20 is connected to the charger 200 (by detecting whether the voltage VIN or the voltage V2N has a voltage drop, it is determined whether the first battery unit 10 or the second battery unit 20 is installed in the battery system 1), the parallel control unit 120 will turn on the switches SW132 and SW142 in the first charging control device 132 and the second charging control device 142 through control signals CC1 and CC2. At this time, due to the relationship between the diodes, the charger 200 will give priority to charging the battery unit with a lower voltage. Furthermore, if the current sensing value I1 or I2 corresponding to the first battery unit 10 or the second battery unit 20 is less than the charging current setting value CCTH (less than zero), the parallel control unit 120 turns on the switch SW131 in the first discharge control device 131 through the control signal CD1, or turns on the switch S141 in the second discharge control device 141 through the control signal CD2, thereby reducing the conduction loss caused by the first discharge control device 131 or the second discharge control device 141 charging the first battery unit 10 or the second battery unit 20.

[0035] During charging, if the current sensing value I1 or I2 corresponding to the first battery unit 10 or the second battery unit 20 is greater than the charging current setting value CCTH, the parallel control unit 120 turns off the switch SW131 in the first discharge control device 131 through the control signal CD1, or turns off the switch S141 in the second discharge control device 141 through the control signal CD2, so as to avoid the circulating current caused by the unequal voltages of the first battery unit 10 and the second battery unit 20 when the charger 200 is removed. Furthermore, if the current sensing values ​​I1 and I2 corresponding to the first battery unit 10 and the second battery unit 20 are both zero, it means that the charger 200 is removed, or if the current sensing values ​​I1 and I2 are both less than a preset value, the parallel control unit 120 turns off the switches SW132 and SW142 in the first charge control device 132 and the second charge control device 142 through the control signals CC1 and CC2, and stops charging.

[0036] Furthermore, when the first battery unit 10 and the second battery unit 20 are charged or discharged in parallel, if the parallel connection of the first battery unit 10 is to be released online (for example, the first battery unit 10 is hot-swapped), the parallel control unit 120 will turn off the switches SW131 and SW132 in the first discharge control device 131 and the first charge control device 132 through the control signals CD1 and CC1, so that the current of the first battery unit 10 is reduced to zero, thereby releasing the parallel connection of the first battery unit 10. Similarly, when the parallel connection of the second battery unit 20 is to be released online, the parallel control unit 120 will turn off the switches SW141 and SW142 in the second discharge control device 141 and the second charge control device 142 through the control signals CD2 and CC2, so that the current of the second battery unit 20 is reduced to zero.

[0037] In summary, the present invention proposes a battery parallel control circuit supporting online hot swapping, which has the following features: it can be applied to various charging and discharging or charging scenarios including load regeneration, it controls the charging and discharging state and parallel state of multiple battery cells based on a single controller, thereby improving response speed and saving costs, it determines the parallel sequence according to the voltage difference to avoid the generation of reverse current, it can effectively eliminate the reverse current caused by the voltage difference between battery cells, and it can arbitrarily specify the battery to be released from parallel to realize online hot swapping.

[0038] The embodiments of the present invention may be specifically implemented as an apparatus, a method or a computer program product. Accordingly, the embodiments of the present invention may take the form of an entity implemented entirely by hardware, an entity implemented entirely by software (including firmware, resident software, microcode, etc.), or an entity combining software and hardware aspects, which may be generally referred to as a "module" or "system". In addition, the embodiments of the present invention may take the form of a computer program product embodied in any tangible expression medium, and the medium has a computer-usable program code embodied in the medium. In terms of hardware, the present invention may be implemented by applying any of the following technologies or related combinations: separate operating logic of logic gates capable of performing logic functions according to data signals, and an application specific integrated circuit (ASIC), a programmable gate array (PGA) or a field programmable gate array (FPGA) with appropriate combinational logic.

[0039] The above descriptions are only preferred embodiments of the present invention. All equivalent changes and modifications made according to the claims of the present invention should fall within the scope of the present invention.

Claims

1. A battery parallel control circuit for a multi-cell battery system, the multi-cell battery system selectively comprising a first battery cell and a second battery cell, the parallel control circuit comprising: A first current sensing unit and a second current sensing unit are respectively coupled to the negative electrode of the first battery unit and the negative electrode of the second battery unit, and are used to respectively sense the current of the first battery unit and the second battery unit, thereby generating a first current sensing value and a second current sensing value; A first discharge control device and a first charge control device, coupled to the negative electrode of the first battery unit, for controlling the discharge and charge of the first battery unit; A second discharge control device and a second charge control device, coupled to the negative electrode of the second battery unit, for controlling the discharge and charge of the second battery unit; A parallel control unit, coupled to the first current sensing unit, the second current sensing unit, the first battery unit, and the second battery unit, for sensing the battery voltage from the negative electrode of the first battery unit and the negative electrode of the second battery unit, thereby generating a first voltage sensing value and a second voltage sensing value, and generating a plurality of control signals according to the first current sensing value, the second current sensing value, the first voltage sensing value, and the second voltage sensing value to respectively control the first and second discharge control devices, and the first and second charge control devices; The multi-cell battery system may be coupled to a load or a charger, and the multi-cell battery system may discharge the load, or the charger may charge the multi-cell battery system.

2. The battery parallel control circuit as described in claim 1, wherein the first discharge control device includes a first diode and a first switch connected in parallel, the first charge control device includes a second diode and a second switch connected in parallel, the second discharge control device includes a third diode and a third switch connected in parallel, and the second charge control device includes a fourth diode and a fourth switch connected in parallel.

3. A battery parallel control circuit as described in claim 2, wherein the cathode of the first diode is coupled to the cathode of the second diode, the cathode of the third diode is coupled to the cathode of the fourth diode, the anode of the first diode is coupled to the negative electrode of the first battery cell, the anode of the third diode is coupled to the negative electrode of the first battery cell, the anode of the second diode is coupled to the anode of the fourth diode, and the positive electrode of the first battery cell is coupled to the positive electrode of the second battery cell.

4. A battery parallel control circuit as described in claim 2, wherein when the parallel control unit senses that the negative electrode voltage of the load or the charger is greater than zero, it is determined that the multi-cell battery system is coupled to the load, and when the parallel control unit senses that the first voltage sensing value has a voltage drop, it is determined that the multi-cell battery system includes the first battery cell, and the parallel control unit turns on the first switch of the first discharge control device through a first control signal.

5. The battery parallel control circuit as claimed in claim 4, wherein when the parallel control unit senses that the first current sensing value is greater than the discharge current setting value, the parallel control unit further turns on the second switch of the first charging control device through a second control signal.

6. A battery parallel control circuit as described in claim 4, wherein when the parallel control unit senses that the second voltage sensing value has a voltage drop, it is determined that the multi-cell battery system includes the second battery cell, and the parallel control unit turns on the third switch of the second discharge control device through a third control signal, so that the first battery cell is connected in parallel with the second battery cell.

7. A battery parallel control circuit as described in claim 6, wherein when the voltage of the second battery cell is less than the voltage of the first battery cell, the fourth diode in the second charging device will be cut off, and the second battery cell will not output current until the voltage of the second battery cell is greater than the voltage of the first battery cell, and the second battery cell outputs current.

8. A battery parallel control circuit as described in claim 6, wherein when the voltage of the second battery unit is greater than the voltage of the first battery unit, the parallel control unit first turns off the second switch of the first charging control device through the second control signal, and then turns on the third switch of the second discharging control device through the third control signal.

9. A battery parallel control circuit as described in claim 7 or 8, wherein when the second current sensing value is greater than the discharge current setting value, the parallel control unit turns on the fourth switch of the second charging control device through a fourth control signal; and when the first current sensing value is greater than the discharge current setting value, the parallel control unit turns on the second switch of the first charging control device through the second control signal.

10. A battery parallel control circuit as described in claim 6, wherein when the difference between the first voltage sensing value and the second voltage sensing value is less than the voltage difference setting value, the parallel control unit turns on the second switch of the first charging control device through a second control signal; and turns on the fourth switch of the second charging control device through a fourth control signal.

11. A battery parallel control circuit as described in claim 6, wherein when the parallel control unit determines that the current direction of one of the first battery unit and the second battery unit is opposite to the discharge current direction and exceeds the reverse current setting value based on the first current sensing value and the second current sensing value, the parallel control unit turns off the switch of the charging control device corresponding to one of the first battery unit and the second battery unit through a control signal.

12. A battery parallel control circuit as described in claim 2, wherein when the parallel control unit senses that the negative electrode voltage of the load or the charger is less than zero, it is determined that the charger is coupled to the multi-cell battery system, and when the parallel control unit senses that the first voltage sensing value has a voltage drop, it is determined that the multi-cell battery system includes the first battery cell, and the parallel control unit turns on the second switch of the first charging control device through a second control signal.

13. The battery parallel control circuit as claimed in claim 12, wherein when the parallel control unit senses that the first current sensing value is less than the charging current setting value, the parallel control unit further turns on the first switch of the first discharge control device through a first control signal.

14. A battery parallel control circuit as described in claim 12, wherein when the parallel control unit senses that the second voltage sensing value has a voltage drop, it is determined that the multi-cell battery system includes the second battery cell, and the parallel control unit turns on the fourth switch of the second charging control device through a fourth control signal.

15. The battery parallel control circuit as claimed in claim 14, wherein when the first current sensing value is greater than the charging current setting value, the parallel control unit turns off the first switch of the first discharge control device through a first control signal; and when the second current sensing value is greater than the charging current setting value, the parallel control unit turns off the third switch of the second discharge control device through a third control signal.

16. The battery parallel control circuit as described in claim 14, when the first current sensing value and the second current sensing value are both zero, the parallel control unit turns off the second switch of the first charging control device through a second control signal, and turns off the fourth switch of the second charging control device through a fourth control signal.

17. The battery parallel control circuit as described in claim 6 or 14, when the first battery unit needs to be removed from the multi-unit battery system, the parallel control unit turns off the first switch of the first discharge control device through a first control signal, and turns off the second switch of the first charge control device through a second control signal; and when the second battery unit needs to be removed from the multi-unit battery system, the parallel control unit turns off the third switch of the second discharge control device through a third control signal, and turns off the fourth switch of the second charge control device through a fourth control signal.

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