Double-battery-pack parallel charging and discharging control method

Abstract

The invention discloses a double-battery-pack parallel charging and discharging control method, and relates to the field of batteries, and the double-battery-pack parallel charging and discharging control method comprises a charging control method and a discharging control method. The discharging control method comprises the following steps: step 1, after the VCU is awakened and before a hard wire signal is output to control the battery pack to be awakened, a corresponding CAN instruction is sent to the two BMSs, compared with the prior art, the method has the beneficial effects that the VCU, the battery pack and the BMSs are adopted to carry out CAN communication interaction, and by comparing the voltage and temperature of the two battery packs, the battery pack can be controlled to be awakened; the charging and discharging time sequence of the two battery packs is controlled; under the condition that configurations such as a unilateral diode, a relay and a controller are not added, double-pack parallel charging and discharging use is realized, and the use cost of the system and the after-sales maintenance cost of components are reduced; and meanwhile, the control strategy is compatible with single-packet use and double-packet use, so that the management and control maintenance pressure of the software version and the probability of misuse of the software version are reduced.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a method for controlling the parallel charging and discharging of dual battery packs. Background Art

[0002] The current development of new energy, whether it is energy storage or automotive power scenarios, often requires battery packs of different capacities due to differences in demand for endurance. In order to avoid or reduce the development costs caused by developing battery packs of different capacities, the use of standard battery boxes for series and parallel use is currently a very common approach.

[0003] Most existing technical solutions, when using two or more packages in parallel, in addition to the basic high and low voltage wiring harness connection, also need to configure a unidirectional diode ①, relay ②, controller ③ and corresponding connecting copper bus and control wiring harness (such as Figure 1 As shown in the figure, the whole system is complex in both structure and control, which increases the cost and failure risk and needs to be improved. Summary of the invention

[0004] The object of the present invention is to provide a method for controlling the parallel charging and discharging of dual battery packs to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: A dual battery pack parallel charging and discharging control method, including a charging control method and a discharging control method; The discharge control method comprises the following steps: Step 1: After the VCU is awakened, before outputting a hard-wire signal to control the battery pack to wake up, it sends corresponding CAN instructions to the two BMSs. The CAN instructions include insulation detection, relay adhesion detection, heating, and high-voltage control. Step 2: After the battery pack is awakened, the current status information of the battery pack is sent to the VCU. The status information of the battery pack includes the battery voltage and the battery temperature. Step 3, the VCU controls the high-voltage discharge of the battery pack according to the received current battery pack status information; Step 4: During the discharge process, the VCU monitors the working status of the two battery packs in real time; The application equipment of the dual battery pack parallel charging and discharging control method includes a VCU (vehicle control unit), a BMS (battery management system), and a battery pack. CAN communication is adopted between the VCU, the BMS and the battery pack. The BMS is connected to the battery pack. There is a BMS and a battery pack on one line, and there are two lines in total.

[0006] As a further solution of the present invention: in step 3, when the temperature of a battery pack is lower than a threshold value (for example, the threshold value is 0°C), the battery pack with a higher voltage is controlled to discharge at a high voltage, and the voltage difference and temperature change between the two battery packs are compared in real time during the discharge process. When the voltage difference meets the requirement (for example, 3V) and the temperature also meets the condition, the other battery pack is controlled to discharge at a high voltage; When the temperatures of the two battery packs are both higher than the threshold (for example, the threshold is 0°C), the voltage difference between the two battery packs is compared. If the voltage difference exceeds the set value (for example, 3V), the battery pack with a higher voltage is first controlled to discharge at high voltage. During the discharge process, the voltage difference between the two battery packs is compared in real time. When the voltage difference meets the requirement, the other battery pack is controlled to discharge at high voltage. When the temperatures of the two battery packs are both higher than a threshold value (for example, the threshold value is 0°C) and the voltage difference between the two battery packs is within a set value range (for example, 3V), the two battery packs are simultaneously controlled to increase the high voltage.

[0007] As a further solution of the present invention: in step 4, during the discharge process, the working status of the two battery packs is monitored in real time, and if a battery pack has a lower high voltage (corresponding to an upper high voltage) based on BMS protection, the safety detection function of the battery pack is switched (such as insulation detection); As a further solution of the present invention: the discharge control method further includes step 5. During the discharge process, if the user actively powers off and turns off the wake-up of the VCU, the VCU stops sending the hard-line wake-up output and clears and resets each CAN enable instruction.

[0008] As a further solution of the present invention: the charging control method comprises the following steps: Step 1: The BMS corresponding to the first battery pack interacts with the fast charging pile according to the national standard protocol and executes the charging process; Step 2: The VCU selects to control the second battery pack to charge directly or to heat the second battery pack before charging according to the current temperature of the second battery pack; Step 3: During the charging process, the cell voltage of the second battery pack is identified to confirm whether the battery is fully charged, thereby controlling whether to stop charging the second battery pack.

[0009] As a further solution of the present invention: in step 2, if the current temperature of the second battery pack reaches the threshold, the VCU controls the second battery pack to charge directly; if the current temperature of the second battery pack does not reach the threshold, the second battery pack is heated so that after the temperature of the second battery pack reaches the threshold, the VCU controls the second battery pack to charge.

[0010] As a further solution of the present invention: the charging control method also includes step 4, during the charging process, by identifying the charging state of the first battery pack and the voltage difference between the two battery packs, thereby controlling whether the second battery pack is discharged at high voltage again.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention adopts VCU, battery pack, and BMS to perform CAN communication interaction, and controls the charging and discharging timing of the two battery packs by comparing the voltage and temperature of the two battery packs; without adding unidirectional diodes, relays, controllers and other configurations, dual-pack parallel charging and discharging is realized, thereby reducing the system use cost and component after-sales maintenance cost; at the same time, the control strategy is compatible with single-pack use and dual-pack use, reducing the management and maintenance pressure of software versions and the probability of using the wrong software version. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of the existing dual battery pack parallel charging and discharging.

[0013] Figure 2 It is a schematic diagram of the structure of a dual battery pack connected in parallel for charging and discharging.

[0014] Figure 3 A schematic diagram of a dual battery pack parallel charging and discharging control method. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0016] See also Figure 2 and 3 , a dual battery pack parallel charging and discharging control method, including a charging control method and a discharging control method; The discharge control method comprises the following steps: Step 1: After the VCU is awakened, before outputting a hard-wire signal to control the battery pack to wake up, it sends corresponding CAN instructions to the two BMSs. The CAN instructions include insulation detection, relay adhesion detection, heating, and high-voltage control. Step 2: After the battery pack is awakened, the current status information of the battery pack is sent to the VCU. The status information of the battery pack includes the battery voltage and the battery temperature. Step 3, the VCU controls the high-voltage discharge of the battery pack according to the received current battery pack status information; Step 4: During the discharge process, the VCU monitors the working status of the two battery packs in real time; The application equipment of the dual battery pack parallel charging and discharging control method includes a VCU (vehicle control unit), a BMS (battery management system), and a battery pack. CAN communication is adopted between the VCU, the BMS and the battery pack. The BMS is connected to the battery pack. There is a BMS and a battery pack on one line, and there are two lines in total.

[0017] In the specific embodiment: see Figure 2 The battery pack includes a consistent number of CMUs (cell management systems) and battery packs, and a battery pack consists of multiple batteries connected in series.

[0018] As the control center of the system, VCU coordinates the BMS control timing of the two battery packs; in addition to being an execution unit, BMS is also responsible for determining whether the working status of the battery pack is normal. VCU uses two CAN channels to communicate with the BMS of the two battery packs respectively. After defining one CAN channel as the first battery pack, by default, all lines and interactions related to external charging plugs occur on this pack.

[0019] See also Figure 2 and 3 In step 3, when the temperature of a battery pack is lower than a threshold value (for example, the threshold value is 0°C), the battery pack with a higher voltage is controlled to discharge at a high voltage. During the discharge process, the voltage difference and temperature change between the two battery packs are compared in real time. When the voltage difference meets the requirement (for example, 3V) and the temperature also meets the conditions, the other battery pack is controlled to discharge at a high voltage. When the temperatures of the two battery packs are both higher than the threshold (for example, the threshold is 0°C), the voltage difference between the two battery packs is compared. If the voltage difference exceeds the set value (for example, 3V), the battery pack with a higher voltage is first controlled to discharge at high voltage. During the discharge process, the voltage difference between the two battery packs is compared in real time. When the voltage difference meets the requirement, the other battery pack is controlled to discharge at high voltage. When the temperatures of the two battery packs are both higher than a threshold value (for example, the threshold value is 0°C) and the voltage difference between the two battery packs is within a set value range (for example, 3V), the two battery packs are simultaneously controlled to increase the high voltage.

[0020] Here, 0°C is used as the threshold value and 3V is used as the set value. In actual use, there is no limit on the size of the threshold value and the set value, and they can be adjusted according to actual conditions.

[0021] See also Figure 2 and 3 ,In step 4, during the discharge process, the working status of the two battery packs is monitored in real time. If a battery pack has a lower high voltage (corresponding to the upper high voltage) based on the BMS protection, the safety detection function of the battery pack is switched (such as insulation detection).

[0022] If the voltage drops during discharge, it may be due to leakage, insufficient battery voltage in the battery pack, etc.

[0023] See also Figure 2 and 3 The discharge control method further includes step 5. During the discharge process, if the user actively powers off and turns off the wake-up of the VCU, the VCU stops sending the hard-line wake-up output and clears and resets each CAN enable instruction.

[0024] Turning off the VCU means stopping charging and discharging, clearing and resetting each CAN enable instruction, and restoring the related settings to their initial state.

[0025] See also Figure 2 and 3 , the charging control method comprises the following steps: Step 1: The BMS corresponding to the first battery pack interacts with the fast charging pile according to the national standard protocol and executes the charging process; Step 2: The VCU selects to control the second battery pack to charge directly or to heat the second battery pack before charging according to the current temperature of the second battery pack; Step 3: During the charging process, the cell voltage of the second battery pack is identified to confirm whether the battery is fully charged, thereby controlling whether to stop charging the second battery pack.

[0026] See also Figure 2 and 3 In step 2, if the current temperature of the second battery pack reaches the threshold, the VCU controls the second battery pack to charge directly; if the current temperature of the second battery pack does not reach the threshold, the second battery pack is heated so that the temperature of the second battery pack reaches the threshold, and then the VCU controls the second battery pack to charge.

[0027] See also Figure 2 and 3 The charging control method further includes step 4, during the charging process, by identifying the charging state of the first battery pack and the voltage difference between the two battery packs, thereby controlling whether the second battery pack is discharged at high voltage again.

[0028] During the charging process, electricity may be used at the same time. Therefore, after the second battery pack has high voltage discharge and the high voltage is reduced due to insufficient battery pack voltage, charging makes the second battery pack restore high voltage and controls the high voltage discharge of the second battery pack again.

[0029] The present invention adopts VCU, battery pack and BMS to perform CAN communication interaction, and controls the charging and discharging timing of the two battery packs by comparing the voltage and temperature of the two battery packs; without adding configurations such as unidirectional diodes, relays and controllers, the parallel charging and discharging of the two packs is realized, thereby reducing the system use cost and the after-sales maintenance cost of components; at the same time, the control strategy is compatible with the use of a single pack and the use of two packs, thereby reducing the management and maintenance pressure of the software version and the probability of using the wrong software version.

[0030] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered as exemplary and non-restrictive in all respects.

[0031] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A dual battery pack parallel charging and discharging control method, including a charging control method and a discharging control method; It is characterized in that The discharge control method comprises the following steps: Step 1: After the VCU is awakened, before outputting a hard-wire signal to control the battery pack to wake up, it sends corresponding CAN instructions to the two BMSs. The CAN instructions include insulation detection, relay adhesion detection, heating, and high-voltage control. Step 2: After the battery pack is awakened, the current status information of the battery pack is sent to the VCU. The status information of the battery pack includes the battery voltage and the battery temperature. Step 3, the VCU controls the high-voltage discharge of the battery pack according to the received current battery pack status information; Step 4: During the discharge process, the VCU monitors the working status of the two battery packs in real time; The application equipment of the dual battery pack parallel charge and discharge control method includes a VCU, a BMS, and a battery pack. CAN communication is adopted between the VCU, the BMS, and the battery pack. The BMS is connected to the battery pack. There is a BMS and a battery pack on one line, and there are two lines in total.

2. The dual battery pack parallel charging and discharging control method according to claim 1, characterized in that: In step 3, when the temperature of a battery pack is lower than the threshold, the battery pack with a higher voltage is controlled to discharge at a high voltage. During the discharge process, the voltage difference and temperature change between the two battery packs are compared in real time. When the voltage difference meets the requirements and the temperature also meets the conditions, the other battery pack is controlled to discharge at a high voltage. When the temperatures of the two battery packs are both higher than the threshold, the voltage difference between the two battery packs is compared. If the voltage difference exceeds the set value, the battery pack with the higher voltage is first controlled to discharge at high voltage. During the discharge process, the voltage difference between the two battery packs is compared in real time. When the voltage difference meets the requirement, the other battery pack is controlled to discharge at high voltage. When the temperatures of the two battery packs are both higher than the threshold and the voltage difference between the two battery packs is within the set value range, the two battery packs are controlled to increase the high voltage at the same time.

3. The dual battery pack parallel charging and discharging control method according to claim 1, characterized in that: In step 4, during the discharge process, the working status of the two battery packs is monitored in real time. If a battery pack has a low voltage due to BMS protection, the safety detection function of the battery pack is switched.

4. The dual battery pack parallel charge and discharge control method according to claim 1, characterized in that: The discharge control method further includes step 5, during the discharge process, if the user actively powers off and turns off the wake-up of the VCU, the VCU stops sending the hard-line wake-up output and clears and resets each CAN enable instruction.

5. The method for controlling parallel charging and discharging of dual battery packs according to any one of claims 1 to 4, characterized in that: The charging control method comprises the following steps: Step 1: The BMS corresponding to the first battery pack interacts with the fast charging pile according to the national standard protocol and executes the charging process; Step 2: The VCU selects to control the second battery pack to charge directly or to heat the second battery pack before charging according to the current temperature of the second battery pack; Step 3: During the charging process, the cell voltage of the second battery pack is identified to confirm whether the battery is fully charged, thereby controlling whether to stop charging the second battery pack.

6. The dual battery pack parallel charge and discharge control method according to claim 5, characterized in that: In step 2, if the current temperature of the second battery pack reaches the threshold, the VCU controls the second battery pack to charge directly; if the current temperature of the second battery pack does not reach the threshold, the second battery pack is heated so that the temperature of the second battery pack reaches the threshold, and then the VCU controls the second battery pack to charge.

7. The method for controlling parallel charging and discharging of dual battery packs according to claim 5, characterized in that: The charging control method further includes step 4, during the charging process, by identifying the charging state of the first battery pack and the voltage difference between the two battery packs, thereby controlling whether the second battery pack is discharged at high voltage again.

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