An electric vehicle battery feedback charging circuit, heating circuit and control method

Abstract

The application discloses an electric vehicle battery feedback charging circuit, a heating circuit and a control method, and relates to the technical field of electric vehicle battery feedback charging circuits, which comprises an electric vehicle battery feedback charging circuit and a battery heating unit, and the current temperature of a battery pack is acquired to monitor the current temperature, and it is determined whether the current temperature is less than a preset temperature threshold value; if the current temperature is less than the preset temperature threshold value, the switching elements in the electric vehicle battery feedback charging circuit and the switching elements in the battery heating unit are closed, so that the corresponding capacitors discharge the heating elements, the heating elements heat the battery pack, and the multiple capacitors can simultaneously heat the battery pack, and the strategy of hierarchical heating can also be realized.

Description

Technical Field

[0001] This invention relates to the field of battery heating technology, and in particular to a regenerative charging circuit, heating circuit, and control method for electric vehicle batteries. Background Technology

[0002] With the technological advancements in electric vehicles, current battery technology faces significant safety risks during discharge at temperatures below -30°C due to technological bottlenecks. Therefore, a key technical challenge is how to briefly heat the battery cells below -30°C to raise them above -30°C for discharge during driving. Current research focuses on improving low-temperature performance at the cell level by adjusting the formulation ratios, enabling the cells to discharge at temperatures below -30°C. Alternatively, insulation designs are implemented for the entire battery pack or vehicle to maintain a cell temperature above -30°C.

[0003] Current pulse self-heating and resistance wire heating technologies both rely on the cell's own discharge to heat the cell, and these technologies depend on the cell's discharge temperature range. Supercapacitors, with their wider operating temperature range—allowing them to discharge as low as -60 degrees Celsius—offer a new approach to solving the problem of low-temperature heating in vehicles due to their unique performance advantages. However, how to apply supercapacitors to battery heating in low-temperature environments within vehicles requires further consideration. Summary of the Invention

[0004] To address the aforementioned technical problems, embodiments of the present invention provide an electric vehicle battery regenerative charging circuit, a heating circuit, and a control method to solve the problem of how to use supercapacitors to heat batteries in low-temperature environments in existing cold-environment battery heating technologies.

[0005] A first aspect of this invention provides a battery regenerative charging circuit for electric vehicles. The circuit includes a battery power supply unit, a battery regenerative charging unit, and a battery management system.

[0006] The battery-powered unit includes a first relay (21), a second relay (22), a third relay (23), a first resistor (31), a fuse (41), a first diode (51), and a first analog-to-digital converter (81), wherein,

[0007] The first terminal of the first relay (21) and the first terminal of the first resistor (31) are connected to the positive terminal of the battery pack (10). The second terminal of the first relay (21) is connected to the first terminal of the fuse (41). The second terminal of the first resistor (31) is connected to the first terminal of the third relay (23). The second terminal of the third relay (23) is connected to the first terminal of the fuse (41). The second terminal of the fuse (41) is connected to the positive terminal of the first diode (51). The negative terminal of the first diode (51) is connected to the positive terminal of the first analog-to-digital converter (81). The negative terminal of the first analog-to-digital converter (81) is connected to the first terminal of the motor.

[0008] The positive terminal of the first analog-to-digital converter (81) is also used to connect to the second terminal of the motor, and the negative terminal of the first analog-to-digital converter (81) is connected to the first terminal of the second relay (22), and the second terminal of the second relay (22) is used to connect to the negative terminal of the battery pack (10).

[0009] The battery recharge unit includes a first capacitor (71), a first inductor (60), a second diode (52), and a transistor (53), wherein,

[0010] The first terminal of the first capacitor (71) is connected to the negative terminal of the first analog-to-digital converter (81), and the second terminal of the first capacitor (71) is connected to the positive terminal of the second diode (52). The negative terminal of the second diode (52) is used to connect to the positive terminal of the battery pack (10).

[0011] The base of the transistor (53) is connected to the battery management system, the collector of the transistor (53) is used to connect to the second terminal of the motor, the emitter of the transistor (53) is connected to the first terminal of the first inductor (60), the second terminal of the first inductor (60) is connected to the first terminal of the second relay (22), and the second terminal of the second relay (22) is used to connect to the negative terminal of the battery pack (10).

[0012] One possible implementation of the first aspect also includes:

[0013] The first relay (21), the second relay (22), and the third relay (23) are respectively connected to the battery management system for the battery management system to control the opening and closing of the first relay (21), the second relay (22), and the third relay (23);

[0014] The fuse (41) is connected in communication with the battery management system to enable the battery management system to monitor the current in the electric vehicle battery recharge circuit.

[0015] To address the same technical problem, a second aspect of this invention provides an electric vehicle battery heating circuit, comprising an electric vehicle battery regenerative charging circuit, a capacitor charging unit, and a battery heating unit, wherein...

[0016] The electric vehicle battery regenerative charging circuit is an electric vehicle battery regenerative charging circuit as claimed in any one of claims 1-2;

[0017] The capacitor charging unit includes a second analog-to-digital converter (82) and a first switching element (24);

[0018] The battery heating unit includes multiple capacitor units, a second resistor (32), a second switching element (28), and a heating element (90), wherein,

[0019] Each capacitor unit includes at least one capacitor and one switching element. The capacitor units are connected in parallel. The first end of the second switching element (28) is connected to the first end of the second resistor (32). The second end of the second switching element (28) is connected to the positive terminal of the heating element (90).

[0020] The first terminal of the first switching element (24) is connected to the positive terminal of the first analog-to-digital converter (81), the second terminal of the first switching element (24) is connected to the positive terminal of the second analog-to-digital converter (82), the negative terminal of the second analog-to-digital converter (82) is connected to the negative terminal of the first analog-to-digital converter (81), and the positive terminal of the second analog-to-digital converter (82) is connected to the first terminal of the second resistor (32).

[0021] The positive terminal of the capacitor in each capacitor unit is connected to the second terminal of the second resistor (32), the negative terminal of the capacitor in each capacitor unit is connected to the first terminal of the corresponding switching element, and the second terminal of each switching element in each capacitor unit is connected to the negative terminal of the heating element (90).

[0022] In one possible implementation of the second aspect, each capacitor unit includes at least one capacitor and one switching element, including:

[0023] Multiple capacitor units include a first capacitor unit, a second capacitor unit, and a third capacitor unit, wherein,

[0024] The first capacitor unit includes a second capacitor (72) and a third switching element (25), the second capacitor unit includes a third capacitor (73) and a fourth switching element (26), and the third capacitor unit includes a fourth capacitor (74) and a fifth switching element (27).

[0025] One possible implementation of the second aspect also includes:

[0026] The second resistor (32) is used to connect to the battery management system and to enable the battery management system to adjust the resistance value of the second resistor (32).

[0027] One possible implementation of the second aspect also includes:

[0028] Each switching element in each capacitor unit is used to connect to the battery management system, so that the battery management system can control the closing and opening of each switching element.

[0029] One possible implementation of the second aspect also includes:

[0030] The second terminal of each switching element in each capacitor unit is connected to the negative terminal of the second analog-to-digital converter (82).

[0031] To address the same technical problem, a third aspect of this invention provides a battery heating control method, implemented via a battery heating circuit as described in any of the second aspects of this invention, comprising:

[0032] Get the current temperature of the battery pack;

[0033] Determine whether the current temperature is lower than a preset temperature threshold. If it is lower than the preset temperature threshold, disconnect the first switching element and close the second and third switching elements so that the second capacitor in the battery heating unit discharges to the heating element, thereby heating the battery pack.

[0034] If the temperature of the battery pack after heating for a preset time is still less than the preset temperature threshold, then close any one of the switching elements in the battery heating unit and continue to check if the temperature of the battery pack after heating for a preset time is still less than the preset temperature threshold. If it is still less than the preset temperature threshold, then close any one of the switching elements in the battery heating unit until the temperature of the battery pack is greater than the preset temperature threshold and then stop heating to allow the battery pack to discharge.

[0035] In one possible implementation of the third aspect, after the battery pack is discharged, it further includes:

[0036] Obtain the regenerative power generated by the electric vehicle while it is in motion;

[0037] Determine whether the feedback power is less than the first preset feedback power threshold. If the feedback power is less than the first preset feedback power threshold, disconnect the first switching element and close the transistor so that the feedback power is converted by the first analog-to-digital converter to charge the battery pack.

[0038] If the feedback power is greater than the first preset feedback power threshold, the voltage of each capacitor in the battery heating unit is obtained, and it is determined whether each voltage is greater than or equal to the voltage threshold. If the voltage is less than the voltage threshold, the first switching element is closed, the second switching element is opened, and multiple switching elements in the battery heating unit are closed so that the feedback power is converted by the first analog-to-digital converter and the second analog-to-digital converter to charge the capacitors in the battery heating unit. If the voltage is greater than or equal to the voltage threshold, the first switching element and multiple switching elements in the battery heating unit are opened.

[0039] One possible implementation of the third aspect also includes:

[0040] When the voltage of each capacitor in the battery heating unit is greater than or equal to the voltage threshold, and if the feedback power is greater than the second preset power threshold, the transistor is closed or opened according to the first preset switching frequency.

[0041] The technical solution of this invention has the following advantages:

[0042] The electric vehicle battery regenerative charging circuit provided in this embodiment of the invention includes a battery power supply unit, a battery recharge unit, and a battery management system. By using the entire battery pack to power the vehicle motor, it can also charge the battery using brake regenerative current to recover kinetic energy.

[0043] The electric vehicle battery heating circuit provided in this invention includes an electric vehicle battery regenerative charging circuit and a battery heating unit. The battery management system controls multiple supercapacitors to supply power to the heating elements by controlling the opening and closing of switching elements, thereby enabling the heating elements to heat the battery. This achieves simultaneous heating of multiple capacitors and can also implement a staged heating strategy, thereby allowing the battery to reach its discharge temperature range. Furthermore, the capacitors in the battery heating unit can also be charged through the battery and brake regenerative current, reducing the power consumption of the lithium battery.

[0044] The battery heating control method provided in this embodiment of the invention obtains the current temperature of the battery pack, monitors the current temperature, and determines whether the current temperature is less than a preset temperature threshold. If it is less than the preset temperature threshold, the switching elements in the electric vehicle battery feedback charging circuit and the switching elements in the battery heating unit are closed, thereby controlling the corresponding capacitor to discharge the heating element, so that the heating element heats the battery pack. This achieves simultaneous heating of the battery by multiple capacitors and can also realize a staged heating strategy. Attached Figure Description

[0045] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the circuit structure of the electric vehicle battery regenerative charging circuit in an embodiment of the present invention;

[0047] Figure 2 This is a schematic diagram of the battery power supply unit circuit structure of the electric vehicle battery regenerative charging circuit in an embodiment of the present invention;

[0048] Figure 3 This is a schematic diagram of the circuit structure of the electric vehicle battery heating circuit in an embodiment of the present invention;

[0049] Figure 4 This is a schematic diagram of the battery feedback charging circuit structure, including a capacitor charging unit, of the electric vehicle battery heating circuit in an embodiment of the present invention.

[0050] Figure 5 This is a schematic diagram of the battery heating unit feedback charging circuit structure of the electric vehicle battery heating circuit in an embodiment of the present invention;

[0051] Figure 6 This is a schematic diagram of the battery heating unit circuit structure of the electric vehicle battery heating circuit in an embodiment of the present invention;

[0052] Figure 7 This is a flowchart of the heating strategy of the battery heating control method in an embodiment of the present invention;

[0053] Figure 8 This is a battery system architecture diagram of the battery heating control method in an embodiment of the present invention;

[0054] Figure 9 This is a current path analysis diagram at the second analog-to-digital converter in the third combination of the emergency mode of the battery heating control method in this embodiment of the invention;

[0055] Figure 10 This is a current path analysis diagram at the second analog-to-digital converter in the third combination of the emergency mode of the battery heating control method in this embodiment of the invention;

[0056] The reference numerals in the accompanying drawings are as follows: 10-Battery pack; 21-First relay; 22-Second relay; 23-Third relay; 24-First switching element; 25-Third switching element; 26-Fourth switching element; 27-Fifth switching element; 28-Second switching element; 31-First resistor; 32-Second resistor; 41-Fuse; 51-First diode; 52-Second diode; 53-Transistor; 60-First inductor; 71-First capacitor; 72-Second capacitor; 73-Third capacitor; 74-Fourth capacitor; 81-First analog-to-digital converter; 82-Second analog-to-digital converter; 90-Heating element. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] In the description of this invention, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0059] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also refer to the internal connection of two components; it can be a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0060] The electric vehicle battery regenerative charging circuit provided in this embodiment of the invention, such as... Figure 1 As shown, the electric vehicle battery regenerative charging circuit includes a battery power supply unit, a battery recharge unit, and a battery management system. The battery power supply unit includes a first relay (21), a second relay (22), a third relay (23), a first resistor (31), a fuse (41), a first diode (51), and a first analog-to-digital converter (81).

[0061] The first terminal of the first relay (21) and the first terminal of the first resistor (31) are connected to the positive terminal of the battery pack (10). The second terminal of the first relay (21) is connected to the first terminal of the fuse (41). The second terminal of the first resistor (31) is connected to the first terminal of the third relay (23). The second terminal of the third relay (23) is connected to the first terminal of the fuse (41). The second terminal of the fuse (41) is connected to the positive terminal of the first diode (51). The negative terminal of the first diode (51) is connected to the positive terminal of the first analog-to-digital converter (81). The negative terminal of the first analog-to-digital converter (81) is connected to the first terminal of the motor.

[0062] The positive terminal of the first analog-to-digital converter (81) is also used to connect to the second terminal of the motor, and the negative terminal of the first analog-to-digital converter (81) is connected to the first terminal of the second relay (22), and the second terminal of the second relay (22) is used to connect to the negative terminal of the battery pack (10).

[0063] The battery recharge unit includes a first capacitor (71), a first inductor (60), a second diode (52), and a transistor (53), wherein,

[0064] The first terminal of the first capacitor (71) is connected to the negative terminal of the first analog-to-digital converter (81), and the second terminal of the first capacitor (71) is connected to the positive terminal of the second diode (52). The negative terminal of the second diode (52) is used to connect to the positive terminal of the battery pack (10).

[0065] The base of the transistor (53) is connected to the battery management system, the collector of the transistor (53) is used to connect to the second terminal of the motor, the emitter of the transistor (53) is connected to the first terminal of the first inductor (60), the second terminal of the first inductor (60) is connected to the first terminal of the second relay (22), and the second terminal of the second relay (22) is used to connect to the negative terminal of the battery pack (10).

[0066] In this embodiment, as Figure 1 As shown, this is a battery regenerative charging circuit for an electric vehicle, including a battery power supply unit, a battery recharge unit, a battery management system (BMS), and a battery pack (10). The battery power supply unit includes a first relay (21), a second relay (22), a third relay (23), a first resistor (31), a fuse (41), a first diode (51), and a first analog-to-digital converter (81).

[0067] The first terminal of the first relay (21) and the first terminal of the first resistor (31) are connected to the positive terminal of the battery pack (10). The second terminal of the first relay (21) is connected to the first terminal of the fuse (41). The second terminal of the first resistor (31) is connected to the first terminal of the third relay (23). The second terminal of the third relay (23) is connected to the first terminal of the fuse (41). The second terminal of the fuse (41) is connected to the positive terminal of the first diode (51). The negative terminal of the first diode (51) is connected to the positive terminal of the first analog-to-digital converter (81). The negative terminal of the first analog-to-digital converter (81) is connected to the first terminal of the motor. The positive terminal of the first analog-to-digital converter (81) is also connected to the second terminal of the motor. The negative terminal of the first analog-to-digital converter (81) is connected to the first terminal of the second relay (22). The second terminal of the second relay (22) is connected to the negative terminal of the battery pack (10).

[0068] like Figure 2 As shown, when the battery supplies power to the vehicle motor, the battery management system first controls the pre-charge relay and the main negative relay to close, boosting the voltage at the vehicle end. When the voltage reaches the matching voltage with the battery, the pre-charge relay opens, the main positive relay closes, and the battery continues to provide power for the entire battery pack. During this process, the current in the current monitoring circuit is monitored, and the battery management system controls the battery's output power accordingly. When the current exceeds the limit current, the battery management system outputs a power limit signal, and the current is converted from DC to AC power usable by the first analog-to-digital converter (81) to drive the vehicle.

[0069] It should be noted that the pre-charge relay refers to the third relay (23), the main negative relay refers to the second relay (22), and the main positive relay refers to the first relay (21).

[0070] The battery recharge unit includes a first capacitor (71), a first inductor (60), a second diode (52), and a transistor (53). The first terminal of the first capacitor (71) is connected to the negative terminal of the first analog-to-digital converter (81), and the second terminal of the first capacitor (71) is connected to the positive terminal of the second diode (52). The negative terminal of the second diode (52) is used to connect to the positive terminal of the battery pack (10). The base of the transistor (53) is connected to the battery management system, the collector of the transistor (53) is used to connect to the second terminal of the motor, the emitter of the transistor (53) is connected to the first terminal of the first inductor (60), the second terminal of the first inductor (60) is connected to the first terminal of the second relay (22), and the second terminal of the second relay (22) is used to connect to the negative terminal of the battery pack (10).

[0071] During the regenerative charging process, the battery management system monitors the current in the circuit. When the regenerative power is less than the battery's set regenerative power P... max , greater than P minAt this time, the transistor (53) is continuously switched on and off to control the charging voltage of the battery by the first analog-to-digital converter (AC / DC). When the transistor (53) is closed, the motor feedback power is continuously supplied, and the AC / DC current eventually flows to the battery terminal through unidirectional conduction, so that the AC / DC provides the braking feedback power to the battery module for charging. When it is necessary to reduce the output current, the transistor (53) is switched on and off at a certain frequency, and after inductor rectification and capacitor filtering, a low power is output. This method is used when the battery heating unit is fully charged and the feedback power is greater than the feedback P set by the battery. max Excess charging is then used to charge the battery module.

[0072] In one embodiment, it further includes:

[0073] The first relay (21), the second relay (22), and the third relay (23) are respectively connected to the battery management system for the battery management system to control the opening and closing of the first relay (21), the second relay (22), and the third relay (23);

[0074] The fuse (41) is connected in communication with the battery management system to enable the battery management system to monitor the current in the electric vehicle battery recharge circuit.

[0075] In this embodiment, the battery management system is connected to the first relay (21), the second relay (22) and the third relay (23) via CAN communication to control their opening and closing; the battery management system is also connected to the fuse (41) via CAN communication to monitor the current in the electric vehicle battery regenerative charging circuit.

[0076] The electric vehicle battery heating circuit provided in this embodiment of the invention, such as... Figure 3 As shown, Figure 3 The circuit diagram for an electric vehicle battery heating circuit includes an electric vehicle battery regenerative charging circuit, a capacitor charging unit, and a battery heating unit.

[0077] The electric vehicle battery regenerative charging circuit is as described in the embodiments of the present invention.

[0078] The capacitor charging unit includes a second analog-to-digital converter (82) and a first switching element (24);

[0079] The battery heating unit includes multiple capacitor units, a second resistor (32), a second switching element (28), and a heating element (90), wherein,

[0080] Each capacitor unit includes at least one capacitor and one switching element. The capacitor units are connected in parallel. The first end of the second switching element (28) is connected to the first end of the second resistor (32). The second end of the second switching element (28) is connected to the positive terminal of the heating element (90).

[0081] The first terminal of the first switching element (24) is connected to the positive terminal of the first analog-to-digital converter (81), the second terminal of the first switching element (24) is connected to the positive terminal of the second analog-to-digital converter (82), the negative terminal of the second analog-to-digital converter (82) is connected to the negative terminal of the first analog-to-digital converter (81), and the positive terminal of the second analog-to-digital converter (82) is connected to the first terminal of the second resistor (32).

[0082] The positive terminal of the capacitor in each capacitor unit is connected to the second terminal of the second resistor (32), the negative terminal of the capacitor in each capacitor unit is connected to the first terminal of the corresponding switching element, and the second terminal of each switching element in each capacitor unit is connected to the negative terminal of the heating element (90).

[0083] In this embodiment, the electric vehicle battery heating circuit consists of an electric vehicle battery regenerative charging circuit and a battery heating unit. The battery heating unit consists of multiple capacitor units, a second resistor (32), a first switching element (24), a second switching element (28), and a second analog-to-digital converter (82). Figure 4 and Figure 5 As shown, the battery heating unit is connected to a DC / DC converter and to an AC / DC converter used for powering the vehicle. During the uphill climb or when high power is output for a short period of time, the battery heating unit can supplement the battery power supply with short-term high power output by closing the third switch element (25), the fourth switch element (26), and the fifth switch element (27).

[0084] When the current in the battery management system monitoring circuit is greater than the battery's set feedback P, max or less than P min At this time, the first switching element (24) is closed, and the AC / DC converter will transform the current generated by the feedback to make it suitable for the charging voltage range of the supercapacitor. The second switching element (28) is opened, and the third switching element (25), the fourth switching element (26) and the fifth switching element (27) are closed to perform feedback charging.

[0085] It should be noted that AC / DC refers to the first analog-to-digital converter (81), DC / DC refers to the second analog-to-digital converter (82), and the second resistor (32) is a variable resistor.

[0086] When the battery heating unit is fully charged, the first switching element (24) and the second switching element (28) are disconnected, and the heating module storage unit stores the charge. If there is feedback power P during driving... max If the output current is reduced, the transistor (53) will be switched on at a certain frequency. After inductor rectification and capacitor filtering, the low power output will charge the battery.

[0087] In one embodiment, each capacitor unit includes at least one capacitor and one switching element, including:

[0088] Multiple capacitor units include a first capacitor unit, a second capacitor unit, and a third capacitor unit, wherein,

[0089] The first capacitor unit includes a second capacitor (72) and a third switching element (25), the second capacitor unit includes a third capacitor (73) and a fourth switching element (26), and the third capacitor unit includes a fourth capacitor (74) and a fifth switching element (27).

[0090] In this embodiment, as Figure 6 As shown, the battery heating unit includes multiple capacitor units, such as a first capacitor unit, a second capacitor unit, and a third capacitor unit. Each capacitor unit includes a capacitor and a corresponding switching element for controlling the capacitor. The first capacitor unit includes a second capacitor (72) and a third switching element (25). The second capacitor unit includes a third capacitor (73) and a fourth switching element (26). The third capacitor unit includes a fourth capacitor (74) and a fifth switching element (27).

[0091] In one embodiment, it further includes:

[0092] The second resistor (32) is used to connect to the battery management system and to enable the battery management system to adjust the resistance value of the second resistor (32).

[0093] In this embodiment, the second resistor (32) is also controlled by the battery management system to further control the charging and discharging speed of the capacitor. The smaller the resistance value, the faster the capacitor charges and discharges; the larger the resistance value, the slower the capacitor charges and discharges.

[0094] When the ambient temperature inside the battery pack is lower than the minimum acceptable temperature for the battery, the battery management system activates the switch, controlling the third switch element (25) and the second switch element (28). Simultaneously, the variable resistor value is adjusted according to the heating rate, allowing the supercapacitor to supply power to the heating element and controlling the heating rate. When the second resistor (32) is adjusted to near zero, and the heating element's temperature increase for the battery cannot reach the dischargeable range, the battery management system continues to control the fourth switch element (26) to close, allowing the second supercapacitor to supply power to the heating element. This method enables simultaneous heating of multiple parallel capacitors and also allows for a graded heating strategy, thereby ensuring the battery reaches the dischargeable temperature range. The vehicle is then started. After the vehicle starts, the second switch element (28) of the battery heating unit is disconnected. Based on the charge of each supercapacitor in the battery heating unit, the battery management system controls the switching on and off of the third switch element (25), the fourth switch element (26), or the fifth switch element (27), realizing a strategy of feedback and battery power supply during driving.

[0095] In one embodiment, it further includes:

[0096] Each switching element in each capacitor unit is used to connect to the battery management system, so that the battery management system can control the closing and opening of each switching element.

[0097] In this embodiment, all switching elements in each capacitor unit are connected to the battery management system, enabling the battery management system to control the opening and closing of each switching element. This can be understood as the third switching element (25), the fourth switching element (26), and the fifth switching element (27) being connected to the battery management system, allowing the battery management system to control the opening and closing of each switching element.

[0098] In one embodiment, it further includes:

[0099] The second terminal of each switching element in each capacitor unit is connected to the negative terminal of the second analog-to-digital converter (82).

[0100] In this embodiment, the second terminals of the third switching element (25), the fourth switching element (26), and the fifth switching element (27) are respectively connected to the negative terminal of the second analog-to-digital converter (82).

[0101] The battery heating control method provided in this embodiment of the invention, such as... Figure 7 As shown, Figure 7 A flowchart of a battery heating control method, including:

[0102] Get the current temperature of the battery pack;

[0103] Determine whether the current temperature is lower than the preset temperature threshold. If it is lower than the preset temperature threshold, disconnect the first switching element and close the second and third switching elements so that the second capacitor in the battery heating unit discharges to the heating element, so that the heating element heats the battery pack.

[0104] If the temperature of the battery pack after heating for a preset time is still less than the preset temperature threshold, then close any one of the switching elements in the battery heating unit and continue to check if the temperature of the battery pack after heating for a preset time is still less than the preset temperature threshold. If it is still less than the preset temperature threshold, then close any one of the switching elements in the battery heating unit until the temperature of the battery pack is greater than the preset temperature threshold and then stop heating to allow the battery pack to discharge.

[0105] In this embodiment, as Figure 8 The battery system architecture diagram shown illustrates the application of an electric vehicle battery heating circuit throughout the entire battery system. The system includes a battery pack, a battery heating unit, and a Battery Disconnect Unit (BDU). The battery heating unit is connected in parallel with the BDU, enabling charging of the battery heating unit during braking or by the battery pack. The BDU comprises a battery power supply unit, a battery recharge unit, and a capacitor charging unit. The battery heating unit consists of two or more capacitors connected in parallel, linked by a controllable switch controlled by the battery management system (BMS). The battery heating unit, connected in parallel with the BDU, is controlled by the BMS, which in turn controls the switch to activate the battery heating unit, allowing it to heat the battery pack at extremely low temperatures.

[0106] It should be noted that controllable switches include, but are not limited to, IGBTs / MOSFETs / Relay switches, etc.

[0107] The on / off state of the battery heating unit is controlled by logic judgment during charging or discharging. The heating strategy of the battery heating unit is as follows: Figure 9 As shown, when the electric vehicle stops for a period of time in extremely cold temperatures, the battery heating unit supplies power to the battery management system when the vehicle starts. The battery heating unit includes a supercapacitor, which supplies power through a power switch such as a controllable switch. The power supply is provided to the battery management system by the supercapacitor.

[0108] After activating the battery management system, the system monitors the battery temperature. When the monitored temperature T < T1, the system controls the first switching element (24) to disconnect and the second switching element (28) and the third switching element (25) to heat the heating element. It also adjusts the variable resistor to control the supercapacitor discharge rate, thereby controlling the heating rate of the heating element. Subsequently, the system monitors the battery temperature. When the temperature T > T1, the entire battery pack starts successfully and the battery discharges. If the temperature T < T1, it controls the next controllable switch in the battery heating unit to increase the power of the capacitor parallel circuit. The system then monitors the battery temperature again. When the temperature T > T1, the entire battery pack starts successfully. When the temperature T ≥ T1, the entire vehicle battery system discharges.

[0109] It should be noted that T is the monitored battery temperature, and T1 is the minimum discharge temperature of the cell, which can be set according to actual needs.

[0110] In one embodiment, after the battery pack is discharged, the method further includes:

[0111] Obtain the regenerative power generated by the electric vehicle while it is in motion;

[0112] Determine whether the feedback power is less than the first preset feedback power threshold. If the feedback power is less than the first preset feedback power threshold, disconnect the first switching element and close the transistor so that the feedback power is converted by the first analog-to-digital converter to charge the battery pack.

[0113] If the feedback power is greater than the first preset feedback power threshold, the voltage of each capacitor in the battery heating unit is obtained, and it is determined whether each voltage is greater than or equal to the voltage threshold. If the voltage is less than the voltage threshold, the first switching element is closed, the second switching element is opened, and multiple switching elements in the battery heating unit are closed so that the feedback power is converted by the first analog-to-digital converter and the second analog-to-digital converter to charge the capacitors in the battery heating unit. If the voltage is greater than or equal to the voltage threshold, the first switching element and multiple switching elements in the battery heating unit are opened.

[0114] In this embodiment, the battery heating unit charging strategy is as follows: Figure 10 As shown, during vehicle operation, braking kinetic energy is recovered. The energy passes through the closed transistor (53) and disconnects the first switching element (24), prioritizing the supply of recovered kinetic energy to the lithium battery. When the feedback power is too large, the feedback power P > P max The feedback power exceeds the value written to the power table in the battery management system. The battery management system first monitors the capacitor voltage. If the current capacitor voltage is less than the maximum capacitor voltage and the feedback power is less than the maximum acceptable power of the capacitor, then the battery heating unit is further charged.

[0115] When the feedback power is too high, the battery management system controls the power input to the battery pack and then shuts off the excess power portion of the controllable switch to power the battery heating unit. The second switching element (28) is disconnected, the first switching element (24) is closed, and the third switching element (25), the fourth switching element (26), and the fifth switching element (27) of the battery heating unit are closed to charge the supercapacitor.

[0116] In one embodiment, it further includes:

[0117] When the voltage of each capacitor in the battery heating unit is greater than or equal to the voltage threshold, and if the feedback power is greater than the second preset power threshold, the transistor is closed or opened according to the first preset switching frequency.

[0118] In this embodiment, when the feedback power is greater than the maximum power received by the capacitor, the battery management system controls the switching frequency of the second switching element (28) to achieve a power reduction strategy for recharging. Subsequently, the battery management system monitors the capacitor voltage. When the monitored capacitor voltage is greater than or equal to the set maximum capacitor voltage, the third switching element (25) is disconnected, and the second switching element (28), the fourth switching element (26), and the fifth switching element (27) of the battery heating unit are disconnected to store energy.

[0119] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0120] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A regenerative charging circuit for electric vehicle batteries, characterized in that, The battery supply unit comprises a first relay (21), a second relay (22), a third relay (23), a first resistor (31), a fuse (41), a first diode (51) and a first analog-to-digital converter (81), wherein, the first end of the first relay (21) and the first end of the first resistor (31) are used to be connected with the positive electrode of the battery pack (10), the second end of the first relay (21) is connected with the first end of the fuse (41), the second end of the first resistor (31) is connected with the first end of the third relay (23), the second end of the third relay (23) is connected with the first end of the fuse (41), the second end of the fuse (41) is connected with the positive electrode of the first diode (51), the negative electrode of the first diode (51) is connected with the positive electrode of the first analog-to-digital converter (81), and the negative electrode of the first analog-to-digital converter (81) is used to be connected with the first end of the motor; the positive electrode of the first analog-to-digital converter (81) is also used to be connected with the second end of the motor, the negative electrode of the first analog-to-digital converter (81) is connected with the first end of the second relay (22), and the second end of the second relay (22) is used to be connected with the negative electrode of the battery pack (10); the battery feedback charging unit comprises a first capacitor (71), a first inductor (60), a second diode (52) and a triode (53), wherein, the first end of the first capacitor (71) is connected with the negative electrode of the first analog-to-digital converter (81), the second end (71) of the first capacitor is connected with the positive electrode of the second diode (52), and the negative electrode of the second diode (52) is used to be connected with the positive electrode of the battery pack (10); the base of the triode (53) is connected with the battery management system, the collector of the triode (53) is used to be connected with the second end of the motor, the emitter of the triode (53) is connected with the first end of the first inductor (60), the second end of the first inductor (60) is connected with the first end of the second relay (22), and the second end of the second relay (22) is used to be connected with the negative electrode of the battery pack (10). Further comprising:

2. The electric vehicle battery regenerative charging circuit of claim 1, wherein, the first relay (21), the second relay (22) and the third relay (23) are respectively connected in communication with the battery management system, so as to enable the battery management system to control the opening and closing of the first relay (21), the second relay (22) and the third relay (23); the fuse (41) is connected in communication with the battery management system, so as to enable the battery management system to monitor the current condition in the electric vehicle battery feedback charging circuit. The battery supply unit comprises a first relay (21), a second relay (22), a third relay (23), a first resistor (31), a fuse (41), a first diode (51) and a first analog-to-digital converter (81), wherein, 3. An electric vehicle battery heating circuit, comprising: the first end of the first relay (21) and the first end of the first resistor (31) are used to be connected with the positive electrode of the battery pack (10), the second end of the first relay (21) is connected with the first end of the fuse (41), the second end of the first resistor (31) is connected with the first end of the third relay (23), the second end of the third relay (23) is connected with the first end of the fuse (41), the second end of the fuse (41) is connected with the positive electrode of the first diode (51), the negative electrode of the first diode (51) is connected with the positive electrode of the first analog-to-digital converter (81), and the negative electrode of the first analog-to-digital converter (81) is used to be connected with the first end of the motor; the positive electrode of the first analog-to-digital converter (81) is also used to be connected with the second end of the motor, the negative electrode of the first analog-to-digital converter (81) is connected with the first end of the second relay (22), and the second end of the second relay (22) is used to be connected with the negative electrode of the battery pack (10); the battery feedback charging unit comprises a first capacitor (71), a first inductor (60), a second diode (52) and a triode (53), wherein, the first end of the first capacitor (71) is connected with the negative electrode of the first analog-to-digital converter (81), the second end (71) of the first capacitor is connected with the positive electrode of the second diode (52), and the negative electrode of the second diode (52) is used to be connected with the positive electrode of the battery pack (10); the base of the triode (53) is connected with the battery management system, the collector of the triode (53) is used to be connected with the second end of the motor, the emitter of the triode (53) is connected with the first end of the first inductor (60), the second end of the first inductor (60) is connected with the first end of the second relay (22), and the second end of the second relay (22) is used to be connected with the negative electrode of the battery pack (10). Further comprising: the first relay (21), the second relay (22) and the third relay (23) are respectively connected in communication with the battery management system, so as to enable the battery management system to control the opening and closing of the first relay (21), the second relay (22) and the third relay (23); the fuse (41) is connected in communication with the battery management system, so as to enable the battery management system to monitor the current condition in the electric vehicle battery feedback charging circuit. The battery supply unit comprises a first relay (21), a second relay (22), a third relay (23), a first resistor (31), a fuse (41), a first diode (51) and a first analog-to-digital converter (81), wherein, the first end of the first relay (21) and the first end of the first resistor (31) are used to be connected with the positive electrode of the battery pack (10), the second end of the first relay (21) is connected with the first end of the fuse (41), the second end of the first resistor (31) is connected with the first end of the third relay (23), the second end of the third relay (23) is connected with the first end of the fuse (41), the second end of the fuse (41) is connected with the positive electrode of the first diode (51), the negative electrode of the first diode (51) is connected with the positive electrode of the first analog-to-digital converter (81), and the negative electrode of the first analog-to-digital converter (81) is used to be connected with the first end of the motor; the positive electrode of the first analog-to-digital converter (81) is also used to be connected with the second end of the motor, the negative electrode of the first analog-to-digital converter (81) is connected with the first end of the second relay (22), and the second end of the second relay (22) is used to be connected with the negative electrode of the battery pack (10); The capacitor charging unit comprises a second analog-to-digital converter (82) and a first switch element (24); The battery heating unit comprises a plurality of capacitor units, a second resistor (32), a second switch element (28) and a heating element (90), wherein, Each of the capacitor units comprises at least one capacitor and one switch element, each of the capacitor units is connected in parallel, a first end of the second switch element (28) is connected to a first end of the second resistor (32), and a second end of the second switch element (28) is connected to a positive electrode of the heating element (90); A first end of the first switch element (24) is connected to a positive electrode of the first analog-to-digital converter (81), a second end of the first switch element (24) is connected to a positive electrode of the second analog-to-digital converter (82), a negative electrode of the second analog-to-digital converter (82) is connected to a negative electrode of the first analog-to-digital converter (81), and a positive electrode of the second analog-to-digital converter (82) is connected to the first end of the second resistor (32); A positive electrode of the capacitor in each of the capacitor units is connected to a second end of the second resistor (32) respectively, a negative electrode of the capacitor in each of the capacitor units is connected to a first end of the corresponding switch element respectively, and a second end of each of the switch elements in each of the capacitor units is connected to a negative electrode of the heating element (90).

4. The electric vehicle battery heating circuit of claim 3, wherein, Each of the capacitor units comprises at least one capacitor and one switch element, comprising: The plurality of capacitor units comprise a first capacitor unit, a second capacitor unit and a third capacitor unit, wherein, The first capacitor unit comprises a second capacitor (72) and a third switch element (25), the second capacitor unit comprises a third capacitor (73) and a fourth switch element (26), and the third capacitor unit comprises a fourth capacitor (74) and a fifth switch element (27).

5. The electric vehicle battery heating circuit of claim 3, wherein, Further comprising: The second resistor (32) is connected to the battery management system, and the battery management system adjusts the resistance value of the second resistor (32).

6. The electric vehicle battery heating circuit of claim 3, wherein, Further comprising: Each of the switch elements in each of the capacitor units is connected to the battery management system, and the battery management system controls the closing and opening of each of the switch elements.

7. The electric vehicle battery heating circuit of claim 3, wherein, Further comprising: The second end of each of the switch elements in each of the capacitor units is connected to a negative electrode of the second analog-to-digital converter (82).

8. A battery heating control method, characterized by, The battery heating circuit is realized by the method as claimed in claim 4, comprising: Obtaining the current temperature of the battery pack; Determining whether the current temperature is less than a preset temperature threshold, if the current temperature is less than the preset temperature threshold, then the first switch element is opened, the second switch element and the third switch element are closed, so that the second capacitor in the battery heating unit discharges the heating element, and the heating element heats the battery pack. If the temperature of the battery pack is still less than the preset temperature threshold after heating for a preset time, any one of the switch elements in the battery heating unit is closed, and it is continuously determined whether the temperature of the battery pack is less than the preset temperature threshold after heating for a preset time. If the temperature of the battery pack is still less than the preset temperature threshold, any one of the switch elements in the battery heating unit is continuously closed until the temperature of the battery pack is greater than the preset temperature threshold, and the heating is stopped, so that the battery pack is discharged.

9. The battery heating control method of claim 8, wherein, After the battery pack is discharged, the method further comprises: obtaining feedback power generated by the electric vehicle during driving; If the feedback power is less than the first preset feedback power threshold, the first switch element is opened, and the triode is closed, so that the feedback power is converted by the first analog-digital converter and then charges the battery pack. If the feedback power is greater than the first preset feedback power threshold, the voltage of each capacitor in the battery heating unit is obtained, and it is determined whether each voltage is greater than or equal to a voltage threshold. If the voltage is less than the voltage threshold, the first switch element is closed, the second switch element is opened, and a plurality of switch elements in the battery heating unit are closed, so that the feedback power is converted by the first analog-digital converter and the second analog-digital converter and then charges the capacitor in the battery heating unit. If the voltage is greater than or equal to the voltage threshold, the first switch element and the plurality of switch elements in the battery heating unit are opened.

10. The battery heating control method of claim 9, wherein, The method further comprises: When each voltage of the capacitor in the battery heating unit is greater than or equal to the voltage threshold, and if the feedback power is greater than a second preset power threshold, the triode is closed or opened at a first preset opening frequency.

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