A heating system, a heating circuit and a heating method for a power battery pack

Abstract

The application provides a heating system, and a heating circuit and a heating method of a power battery pack. In the heating circuit of the power battery pack, when a first switching device is disconnected and a second switching device is connected, a neutral point of a three-phase motor is connected to a positive electrode of the power battery pack through the second switching device, so that the power battery pack can charge a first capacitor branch and the first capacitor branch can charge the power battery pack through the three-phase motor and a motor drive circuit, that is, the charging and discharging of the power battery pack is realized, and the internal resistance of the power battery pack generates heat during the charging and discharging of the power battery pack, so that the heating of the power battery pack can be realized. In addition, in the heating circuit of the power battery pack, only the second switching device is a newly added device, so that the heating circuit of the power battery pack can realize the heating of the power battery pack while reducing the heating cost of the power battery pack.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a heating system and a heating circuit and heating method for a power battery pack. Background Technology

[0002] As a crucial component of new energy vehicles, the power battery pack not only provides power but also stores and recovers energy. Currently, new energy vehicles primarily use lithium-ion batteries. However, the external characteristics of lithium-ion batteries are easily affected by ambient temperature, especially in low-temperature environments, such as below 0°C. In such environments, the capacity and charge / discharge rate of lithium-ion batteries decrease significantly, resulting in reduced driving range and longer charging times for new energy vehicles in low-temperature conditions. Additionally, new energy vehicles suffer from low starting power and poor starting performance, directly impacting the user's driving experience.

[0003] Currently, by adding heating equipment to heat the power battery pack from the outside, it is possible to achieve rapid temperature increase, thereby ensuring the driving capability of new energy vehicles and improving the user's driving experience. However, due to the complexity of the structure and control of the added heating equipment, the heating cost of the power battery pack is relatively high.

[0004] Therefore, how to reduce the heating cost of the power battery pack while achieving heating is an urgent technical problem to be solved. Summary of the Invention

[0005] In view of this, the present invention provides a heating system, a heating circuit and a heating method for a power battery pack, so as to reduce the heating cost of the power battery pack while achieving heating of the power battery pack.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] The first aspect of this application provides a heating circuit for a power battery pack, comprising: a motor drive circuit, a first switching device, a first capacitor branch, and a second switching device; wherein:

[0008] The positive input terminal of the motor drive circuit is connected to the positive terminal of the power battery pack through the first switching device;

[0009] The negative terminal of the motor drive circuit is connected to the negative terminal of the power battery pack.

[0010] The first capacitor branch is connected in parallel between the two poles of the input terminal of the motor drive circuit;

[0011] The three-phase output terminals of the motor drive circuit are respectively connected to the three-phase power supply terminals of the three-phase motor.

[0012] In the three-phase motor, the three-phase windings are connected in a star configuration, and the neutral point of the three-phase motor is connected to the positive terminal of the power battery pack through the second switching device.

[0013] The second switching device closes when the first switching device is open.

[0014] Optionally, the motor drive circuit includes: a three-phase bridge arm; wherein:

[0015] The positive input terminal of each phase of the bridge arm is connected to the positive input terminal of the motor drive circuit, and the negative input terminal of each phase of the bridge arm is connected to the negative input terminal of the motor drive circuit.

[0016] The output terminals of the three-phase bridge arms are respectively used as the three-phase output terminals of the motor drive circuit;

[0017] Each phase of the bridge arm includes two switching transistors; in each phase of the bridge arm, the output terminal of the first switching transistor is connected to the input terminal of the second switching transistor, and the connection point serves as the output terminal of the bridge arm in that phase; the input terminal of the first switching transistor serves as the positive input terminal of the bridge arm in that phase, and the output terminal of the second switching transistor serves as the negative input terminal of the bridge arm in that phase.

[0018] Optionally, the switching transistor is a MOSFET or an IGBT.

[0019] Optionally, the first capacitor branch includes: at least one capacitor; wherein:

[0020] If the number of capacitors is greater than 1, then all the capacitors are connected in series, in parallel, or in a series-parallel connection.

[0021] Optionally, the power battery pack includes: a power battery, a first resistor branch, and a filter branch; wherein:

[0022] The power battery, the first resistor branch, and the filter branch are connected in series, and the two poles of the series branch serve as the two poles of the power battery pack.

[0023] Optionally, the filtering branch includes: a second capacitor branch and a second resistor branch connected in parallel.

[0024] Optionally, the second capacitor branch includes at least one capacitor; if the number of capacitors is greater than 1, then all the capacitors are connected in series, in parallel, or in a series-parallel connection.

[0025] Each resistor branch includes at least one resistor; if the number of resistors is greater than 1, then all the resistors are connected in series, in parallel, or in a series-parallel connection.

[0026] Optionally, the first switching device is a relay, circuit breaker, contactor, MOSFET, or IGBT.

[0027] A second aspect of this application provides a heating method for a power battery pack, used to control the heating circuit of the power battery pack as described in any one of the first aspects of this application; the heating method for the power battery pack includes:

[0028] Determine whether heating of the power battery pack is necessary;

[0029] If it is necessary to heat the power battery pack, the first switch in the heating circuit is turned off, the second switch in the heating circuit is turned on, and the motor drive circuit in the heating circuit is driven to run.

[0030] A third aspect of this application provides a heating system, comprising: a controller, a three-phase motor, and a heating circuit for a power battery pack as described in any of the first aspects of this application; wherein:

[0031] The motor drive circuit, the first switching device, and the second switching device in the heating circuit are all controlled by the controller, which is used to execute the heating method of the power battery pack as described in the second aspect of this application.

[0032] As can be seen from the above technical solution, the present invention provides a heating circuit for a power battery pack, specifically including: a motor drive circuit, a first switching device, a first capacitor branch, and a second switching device. In this heating circuit for the power battery pack, the positive terminal of the motor drive circuit is connected to the positive terminal of the power battery pack through the first switching device; the negative terminal of the motor drive circuit is connected to the negative terminal of the power battery pack; the first capacitor branch is connected in parallel between the two terminals of the input terminal of the motor drive circuit; the three-phase output terminals of the motor drive circuit are respectively connected to the three-phase power supply terminals of the three-phase motor; in the three-phase motor, the three-phase windings are connected in a star configuration, and the neutral point of the three-phase motor is connected to the positive terminal of the power battery through the second switching device; at least one second switching device is closed when the first switching device is open.

[0033] As described above, when the first switch is open and the second switch is closed, the neutral point of the three-phase motor is connected to the positive terminal of the power battery pack through the second switch. Therefore, the power battery pack can charge the first capacitor branch and the first capacitor branch can charge the power battery pack, thus realizing the charging and discharging of the power battery pack. During the charging and discharging process, the internal resistance of the power battery pack generates heat, thereby heating the power battery pack. In addition, in the heating circuit of this power battery pack, only the second switch is a newly added device. Therefore, the heating circuit of this power battery pack reduces the heating cost of the power battery pack while realizing the heating of the power battery pack. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0035] Figure 1 A schematic diagram of one embodiment of the heating circuit of the power battery pack provided in this application;

[0036] Figure 2 for Figure 1 Equivalent circuit diagram;

[0037] Figures 3-5 These are schematic diagrams of three other embodiments of the heating circuit of the power battery pack provided in the embodiments of this application;

[0038] Figure 6 A schematic flowchart illustrating the heating method for a power battery pack provided in an embodiment of this application;

[0039] Figure 7 and Figure 8 These are schematic diagrams of two implementations of the heating system provided in this application. Detailed Implementation

[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0041] In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0042] To achieve heating of the power battery pack while reducing its heating cost, another embodiment of this application provides a heating circuit for the power battery pack, the specific structure of which is as follows: Figure 1 As shown, it specifically includes: a motor drive circuit 10, a first switching device 20, a first capacitor branch 30, and a second switching device 40; the connection relationships between the components are as follows:

[0043] The positive terminal of the input of the motor drive circuit 10 is connected to the positive terminal of the power battery pack 50 through the first switching device 20; the negative terminal of the input of the motor drive circuit 10 is connected to the negative terminal of the power battery pack 50; the first capacitor branch 30 is connected in parallel between the two terminals of the input of the motor drive circuit 10; the three-phase output terminals of the motor drive circuit 10 are respectively connected to the three-phase power supply terminals of the three-phase motor 60.

[0044] Among them, the first capacitor branch 30 ( Figure 1 (The example shown uses only one capacitor C1) includes: at least one capacitor; if the number of capacitors is greater than 1, all capacitors are connected in series, in parallel, or in a series-parallel connection.

[0045] In the three-phase motor 60, the three-phase windings are connected in a star configuration, and the neutral point of the three-phase motor 60 is connected to the positive terminal of the power battery pack 50 through the second switching device 40.

[0046] It should be noted that the three-phase output terminals of the motor drive circuit 10, which are respectively connected to the U-phase winding, V-phase winding, and W-phase winding of the three-phase motor 60, are respectively referred to as the U-phase output terminal, V-phase output terminal, and W-phase output terminal.

[0047] When in electric drive mode, the first switch device 20 is closed and the second switch device 40 is open; when in heating mode, the first switch device 20 is open and the second switch device 40 is closed.

[0048] Therefore, when the first switch device 20 is open and the second switch device 40 is closed, the neutral point of the three-phase motor 60 is connected to the positive terminal of the power battery pack 50 through the second switch device 40, and its equivalent circuit is as follows: Figure 2 As shown, inductors Lu, Lv, and Lw are all equivalent devices of the three-phase windings in the three-phase motor 60.

[0049] As can be seen from the above, when the first switch device 20 is open and the second switch device 40 is closed, the neutral point of the three-phase motor 60 is connected to the positive terminal of the power battery pack 50 through the second switch device 40. Therefore, the power battery pack 50 can charge the first capacitor branch 30 and the first capacitor branch 30 can charge the power battery pack 50 through the three-phase motor 60 and the motor drive circuit 10, thus realizing the charging and discharging of the power battery pack 50. During the charging and discharging process of the power battery pack 50, its internal resistance heats up, thereby realizing the heating of the power battery pack 50. In addition, in the heating circuit of the power battery pack 50, only the second switch device 40 is a newly added device. Therefore, the heating circuit of the power battery pack 50 reduces the heating cost of the power battery pack 50 while realizing the heating of the power battery pack 50.

[0050] In specific examples, each switching device can be a relay, a circuit breaker, a contactor, or even a MOSFET or IGBT. In practical applications, the above-described embodiments are not limited here and can be determined according to the specific circumstances, all of which are within the protection scope of this application. It should be noted that in actual use, the switching device should be a device with high voltage resistance.

[0051] In the existing technology, there is another solution that generates an alternating current at the battery terminals of the power battery pack by applying a periodic alternating voltage vector to the motor, thereby achieving self-heating of the power battery pack. In this solution, the architecture of the drive system is not changed, so it is more economical. The power battery pack heats up evenly and the motor torque is zero. However, the effective value of the charging and discharging current at the power battery terminals is low, and the motor phase current resonance content is high, the rotor temperature rises, the vibration and noise are large, and the bus capacitor voltage surge is large.

[0052] In contrast, in the heating circuit of the power battery pack provided in this application embodiment, when the power battery pack 50 is heated, i.e., when the first switching device 20 is turned off, the connection between the first capacitor branch 30 connected in parallel between the two poles of the input terminal of the motor drive circuit 10 and the power battery pack 50 is disconnected. Therefore, during the charging and discharging process of the power battery pack 50, the first capacitor branch 30 does not filter the charging and discharging current, thereby increasing the effective value of the current at the battery terminal of the power battery pack 50 and shortening the heating time of the power battery pack 50. On the other hand, since the first capacitor branch 30 does not filter the charging and discharging current, when the effective value of the current at the input terminal of the motor drive circuit 10 remains unchanged, the three-phase current of the three-phase motor 60 is lower, thereby reducing the temperature rise of the stator and rotor in the three-phase motor 60 and / or reducing the temperature rise of the motor drive circuit 10. Furthermore, since the first capacitor branch 30 does not filter the charging and discharging current, when the temperature rise of the power battery pack 50 is the same, the battery capacity decay of the power battery pack 50 is smaller and the battery energy utilization rate is higher.

[0053] Another embodiment of this application provides a specific implementation of the motor drive circuit 10, the specific structure of which is as follows: Figure 3 As shown, it specifically includes: three-phase bridge arms 11; the connection relationship between each bridge arm 11 is as follows:

[0054] The positive input terminal of each phase bridge arm 11 is connected to the positive input terminal of the motor drive circuit 10, and the negative input terminal of each phase bridge arm 11 is connected to the negative input terminal of the motor drive circuit 10; the output terminals of the three phase bridge arms 11 serve as the three-phase output terminals of the motor drive circuit 10.

[0055] Each phase bridge arm 11 includes two switching transistors. The output terminal of the first switching transistor Q1 is connected to the input terminal of the second switching transistor Q2, and the connection point serves as the output terminal of the phase bridge arm 11. The input terminal of the first switching transistor Q1 serves as the positive input terminal of the phase bridge arm 11, and the output terminal of the second switching transistor Q2 serves as the negative input terminal of the phase bridge arm 11.

[0056] In specific examples, the switching transistor can be a MOSFET or an IGBT; no specific limitation is made here, and it can be determined according to the specific circumstances, all of which are within the protection scope of this application.

[0057] It should be noted that the specific implementation of the motor drive circuit 10 described above is a relatively mature technology in the prior art, and its working principle will not be described in detail here.

[0058] Another embodiment of this application provides a specific implementation of the power battery pack 50, the specific structure of which is as follows: Figure 4 As shown, it specifically includes: a power battery 51, and a first resistor branch 52. Figure 4 (Taking only resistor R1 as an example for illustration) and filter branch 53; the connection relationships between the components are as follows:

[0059] The power battery 51, the first resistor branch 52, and the filter branch 53 are connected in series, and the two poles of the series branch serve as the two poles of the power battery pack 50.

[0060] The first resistor branch 52 includes at least one resistor; if the number of resistors is greater than 1, all resistors are connected in series, in parallel, or in a series-parallel connection.

[0061] In specific examples, such as Figure 5 As shown, the filter circuit specifically includes a second capacitor branch 531 and a second resistor branch 532, and the second capacitor branch 531 and the second resistor branch 532 are connected in parallel, with the two ends of the parallel branch serving as the two ends of the filter circuit.

[0062] Among them, the second resistor branch 532 ( Figure 5 (Taking only one resistor R2 as an example for demonstration), including: at least one resistor; if the number of resistors is greater than 1, then all resistors are connected in series, in parallel, or in a series-parallel connection.

[0063] Second capacitor branch 531 ( Figure 5 (The example shown uses only one capacitor C2) includes: at least one capacitor; if the number of capacitors is greater than 1, all capacitors are connected in series, in parallel, or in a series-parallel connection.

[0064] The above is only one specific embodiment of the power battery pack 50. In practical applications, the above embodiment is not limited to, but can be determined according to the specific circumstances. All of them are within the protection scope of this application.

[0065] Another embodiment of this application provides a heating method for a power battery pack, which is used to control the heating circuit of the power battery pack provided in the above embodiment; the specific process of the heating method is as follows: Figure 6 As shown, the specific steps include:

[0066] S110. Determine whether the power battery pack needs to be heated.

[0067] If heating of the power battery pack is required, proceed to step S120; if heating of the power battery pack is not required, return to step S110.

[0068] S120. Disconnect the first switch in the heating circuit, close the second switch in the heating circuit, and drive the motor drive circuit in the heating circuit to run.

[0069] Another embodiment of this application also provides a heating system, the specific structure of which can be found in [reference needed]. Figure 7 ( Figure 7 Only Figure 1 Based on the presentation) or Figure 8 ( Figure 8 Only Figure 5 Based on the above embodiments, the present invention includes: a controller 70, a three-phase motor 60, and a heating circuit for a power battery pack 50 as provided in the above embodiments.

[0070] The motor drive circuit 10, the first switching device 20, and all the second switching devices 40 in the heating circuit are controlled by the controller 70, which is used to execute the heating method of the power battery pack 50 provided in the above embodiment.

[0071] It should be noted that, apart from the connection relationships described above, other connection relationships between the devices have been described in detail in the above embodiments, and will not be repeated here.

[0072] The features described above in the disclosed embodiments can be substituted or combined with each other, enabling those skilled in the art to implement or use this application. The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

Claims

1. A heating circuit for a power battery pack, characterized in that, include: The circuit comprises a motor drive circuit, a first switching device, a first capacitor branch, and a second switching device; wherein: The positive input terminal of the motor drive circuit is connected to the positive terminal of the power battery pack through the first switching device; The negative terminal of the motor drive circuit is connected to the negative terminal of the power battery pack. The first capacitor branch is connected in parallel between the two poles of the input terminal of the motor drive circuit; The three-phase output terminals of the motor drive circuit are respectively connected to the three-phase power supply terminals of the three-phase motor. In the three-phase motor, the three-phase windings are connected in a star configuration, and the neutral point of the three-phase motor is connected to the positive terminal of the power battery pack through the second switching device. The second switching device closes when the first switching device is open; The power battery pack includes: a power battery, a first resistor branch, and a filter branch; wherein: The power battery, the first resistor branch, and the filter branch are connected in series, and the two poles of the series branch serve as the two poles of the power battery pack, respectively. The filtering branch includes: a second capacitor branch and a second resistor branch connected in parallel.

2. The heating circuit of the power battery pack according to claim 1, characterized in that, The motor drive circuit includes: a three-phase bridge arm; wherein: The positive input terminal of each phase of the bridge arm is connected to the positive input terminal of the motor drive circuit, and the negative input terminal of each phase of the bridge arm is connected to the negative input terminal of the motor drive circuit. The output terminals of the three-phase bridge arms are respectively used as the three-phase output terminals of the motor drive circuit; Each phase of the bridge arm includes two switching transistors; in each phase of the bridge arm, the output terminal of the first switching transistor is connected to the input terminal of the second switching transistor, and the connection point serves as the output terminal of the bridge arm in that phase; the input terminal of the first switching transistor serves as the positive input terminal of the bridge arm in that phase, and the output terminal of the second switching transistor serves as the negative input terminal of the bridge arm in that phase.

3. The heating circuit of the power battery pack according to claim 2, characterized in that, The switching transistor is a MOSFET or an IGBT.

4. The heating circuit of the power battery pack according to claim 1, characterized in that, The first capacitor branch includes: at least one capacitor; wherein: If the number of capacitors is greater than 1, then all the capacitors are connected in series, in parallel, or in a series-parallel connection.

5. The heating circuit of the power battery pack according to claim 1, characterized in that, The second capacitor branch includes: at least one capacitor; if the number of capacitors is greater than 1, then all the capacitors are connected in series, in parallel, or in a series-parallel connection. Each resistor branch includes at least one resistor; if the number of resistors is greater than 1, then all the resistors are connected in series, in parallel, or in a series-parallel connection.

6. The heating circuit of the power battery pack according to any one of claims 1 to 5, characterized in that, The first switching device is a relay, circuit breaker, contactor, MOSFET, or IGBT.

7. A heating method for a power battery pack, characterized in that, A heating circuit for controlling the power battery pack as described in any one of claims 1 to 6; the heating method for the power battery pack includes: Determine whether heating of the power battery pack is necessary; If it is necessary to heat the power battery pack, the first switch in the heating circuit is turned off, the second switch in the heating circuit is turned on, and the motor drive circuit in the heating circuit is driven to run.

8. A heating system, characterized in that, include: The controller, the three-phase motor, and the heating circuit of the power battery pack as described in any one of claims 1 to 6; wherein: The motor drive circuit, the first switching device, and the second switching device in the heating circuit are all controlled by the controller, which is used to execute the heating method of the power battery pack as described in claim 7.

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