Intelligent fusion terminal of battery heating system based on extremely cold environment and electric energy meter

Abstract

The invention relates to the technical field of electrical variable measurement, and particularly discloses an intelligent fusion terminal and an electric energy meter of a battery heating system based on an extremely cold environment, and the intelligent fusion terminal comprises a high-voltage battery, an inverter, a three-phase motor, an acquisition terminal, an electric energy meter and a relay SMR2. Based on a direct-current resistance heating technology, a high-voltage battery, an inverter, a three-phase motor and a control unit form a charging and discharging heating loop. And the relay SMR2 controls the on-off of the high-voltage battery and an inverter heating loop. The inverter utilizes an insulated gate bipolar transistor (IGBT) and a smoothing capacitor to cooperatively form a buck-boost loop. The three-phase motor serves as a current channel, participates in construction of a direct-current buck-boost heating loop, and preheats peripheral components through heat conduction. The acquisition terminal acquires voltage, current and temperature parameters in real time. The electric energy meter measures energy data in the charging and discharging process. Through intelligent control and real-time monitoring, the system has the advantages of quick response, high efficiency and good adaptability.

Description

Technical Field

[0001] The present invention relates to the technical field of electric variable measurement, and more specifically, to an intelligent fusion terminal and an electric energy meter based on a battery heating system in an extremely cold environment. Background Art

[0002] With the rapid development of lithium-ion battery technology, it has been widely used due to its high energy density, long service life, and environmental friendliness. However, in extremely cold environments, the internal resistance of lithium-ion batteries increases significantly, resulting in a significant reduction in their output power.

[0003] like Figure 1 As shown, a power battery heating system is disclosed. The system adopts a liquid cooling temperature control method and is composed of an expansion kettle, an electric water pump, a PTC heater, a heat exchange pipe, a temperature sensor and a coolant circulation pipeline. Under the dispatch of the vehicle controller (VCU), the coolant is heated and transferred to the battery pack by adjusting the gear of the PTC heater to achieve battery heating. The system has a multi-gear heating function and can dynamically adjust the power output according to the ambient temperature and battery status. However, the heating control strategy of the system failed to effectively coordinate the response process of the charging pile and the heater, resulting in a slow temperature rise.

[0004] like Figure 2 As shown, a flat ultra-thin micro heat pipe is disclosed. The heat pipe is a highly efficient heat-conducting device with a thickness of less than 2 mm and a flattened shape. It uses a copper shell and water as the working fluid, and the liquid-absorbing core is a sintered copper powder structure. The heat pipe has high thermal conductivity, controllable heat flux density and good structural adaptability. It can efficiently transfer heat through an evaporation-condensation cycle in a low-temperature environment, effectively disperse the heat generated by the battery, and prevent heat accumulation and thermal runaway. However, this direct heating method increases the complexity and cost of the battery heating system.

[0005] Therefore, there is an urgent need for a battery heating system with a simple structure that can accelerate the temperature rise of the battery in extremely cold environments. Summary of the invention

[0006] In order to overcome the above-mentioned defects of the prior art, the present invention provides an intelligent fusion terminal and electric energy meter based on a battery heating system in an extremely cold environment. A relay is added between the battery and the three-phase motor, and the three-phase motor winding, the IGBT in the inverter and the smoothing capacitor are used to form a step-up / step-down DC-DC to achieve high-frequency charging and discharging between the battery and the capacitor. The IGBT switching frequency is then optimized by the control unit to ensure that the battery heating system is quickly heated from -20°C to 0°C within 5 minutes, so as to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: An intelligent fusion terminal based on a battery heating system in an extremely cold environment, comprising a battery, a three-phase motor, a control unit, an inverter, a relay SMR2 ​​and a collection terminal; the relay SMR2 ​​is connected to the positive electrode of the battery and the U phase of the three-phase motor to control the IGBT in the inverter to realize a buck-boost DC-DC loop; the collection terminal collects operating parameters in real time; Based on the battery, inverter, three-phase motor, control unit and relay, combined with the data obtained by the acquisition terminal, the control unit optimizes the IGBT switching frequency so that the battery heating system can be quickly heated from -20°C to 0°C within 5 minutes. The specific steps are as follows: S1, after the battery heating system is powered on, the control unit loads default initial operating parameters for trial operation, at which time the collection terminal collects the operating parameters in real time; S2, the battery heating system starts the charge and discharge control at the initial frequency. After completing a control cycle, the control unit obtains the lowest voltage of the battery during the charging process. , battery current RMS value , the heat generated by the battery per unit time , Instantaneous active power on the battery side and thermal efficiency ; S3, if the battery is at the lowest voltage during charging , and the difference ΔV is range, start the frequency increase strategy, each time increase 10Hz, until the voltage rises above 17.8V; if the battery current RMS value is , indicating insufficient heating, reduce the frequency according to the dynamic proportional method. Stop frequency reduction when S4, when the battery temperature , heating is completed and the relay is disconnected.

[0008] As a further solution of the present invention, in S2, the charge and discharge control includes a charging stage and a discharging stage. In the charging stage: the V- and W- lower bridge arm IGBTs are turned on, the battery charges the capacitor through the three-phase motor winding, the smoothing capacitor voltage rises to 600V, the battery current flows, and the acquisition terminal records the current peak and root mean square value; in the discharging stage: the V+ and W+ upper bridge arm IGBTs are turned on, the capacitor discharges the battery, the smoothing capacitor voltage drops back to 300V, the current flows through the battery in the reverse direction, and continues to generate heat.

[0009] As a further solution of the present invention, in S3, the frequency increase strategy adopts a fixed step size method, increasing by 10Hz each time until , that is, the minimum battery voltage returns to the safe range and the frequency increase stops; in S3, the calculation formula of the dynamic proportional method is: ,in, is the new frequency, is the current frequency, is the RMS value of the battery current, is the frequency adjustment factor, and its value range is [1,5].

[0010] As a further solution of the present invention, in S1, the control unit loads the default initial operating parameters for trial operation, specifically including: IGBT switching frequency f_init=50Hz, PWM duty cycle D_init=90%, control period T_ctrl=500ms, heating parameters updated every 500ms, target battery temperature T_target=0℃, heating duration T_total=5 minutes; the operating parameters include: battery voltage , smoothing capacitor voltage , smoothing capacitor current , battery current , Battery temperature , Battery internal resistance , and start recording: instantaneous active power on the battery side , capacitor side power , cumulative consumption .

[0011] As a further solution of the present invention, the battery adopts a lithium-ion battery structure, consisting of seven lithium-ion battery cells connected in series, each cell has a capacity of 9.0Ah, an internal resistance of 1.5mΩ, a positive electrode material of lithium cobalt oxide, a negative electrode material of graphite, and an electrolyte of a liquid organic solvent system.

[0012] As a further solution of the present invention, the inverter is a rectangular metal shell structure, which integrates multiple power semiconductor devices, including IGBTs and diodes. It has the function of converting direct current into three-phase alternating current, and at the same time assumes the function of a step-up and step-down DC-DC converter.

[0013] As a further solution of the present invention, the three-phase motor adopts a cylindrical shell structure with symmetrically arranged three-phase windings inside, and is composed of a copper winding, an iron core and an aluminum alloy shell. The three-phase motor is driven to rotate by three-phase alternating current to achieve power output.

[0014] An electric energy meter based on a battery heating system in an extremely cold environment, the electric energy meter records feedback data during the charging and discharging process, the feedback data includes: the lowest voltage of the battery during the charging process , battery current RMS value , the heat generated by the battery per unit time , Instantaneous active power on the battery side and thermal efficiency , satisfy .

[0015] Technical effects and advantages of an intelligent fusion terminal and electric energy meter based on a battery heating system in an extremely cold environment of the present invention: The present invention uses the IGBT in the inverter to control the charge and discharge path of the current, and uses the internal resistance of the battery and the resistance of the three-phase motor winding to generate Joule heat, thereby quickly raising the battery temperature, effectively solving the problems of slow temperature rise and delayed response in the prior art. The battery heating system of the present invention has a compact structure and does not require the addition of complex heating devices, which reduces the integration cost of the system. At the same time, the control unit can intelligently adjust the IGBT frequency by real-time monitoring of the voltage, current and temperature status through the acquisition terminal and the electric energy meter, so as to increase the battery temperature from -20°C to 0°C within 5 minutes, and has a high energy efficiency adjustment capability and good environmental adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a schematic structural diagram of a power battery heating system in the prior art.

[0017] Figure 2 The figure is a working principle diagram of a heat pipe in the prior art.

[0018] Figure 3 Graph 1 is the switching signal waveform of the lower IGBT of the V- and W-phases in the battery heating system of the present invention.

[0019] Figure 4 This is a temperature variation trend diagram of the battery of the present invention when heated for 5 minutes.

[0020] In the figure: Ton represents the on-time, and Toff represents the off-time. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1 An embodiment of the present invention provides an intelligent fusion terminal based on a battery heating system in an extremely cold environment, which includes a battery, an inverter, a three-phase motor, a collection terminal and a relay SMR2; the battery forms a charging and discharging heating circuit by means of the inverter, the three-phase motor and the control unit; the inverter forms a buck-boost heating circuit by means of an insulated gate bipolar transistor and a capacitor; the three-phase motor participates in constructing a DC buck-boost heating circuit as a current channel; the relay SMR2 ​​constructs a battery and inverter heating circuit by controlling the on-off of the circuit; the collection terminal collects operating parameters in real time and is linked with a controller.

[0023] Furthermore, the lithium-ion battery forms a charging, discharging and heating circuit with an inverter, a three-phase motor and a control unit, including: the battery adopts a lithium-ion battery structure, and its monomer is in a rectangular shape, has good group arrangement characteristics, and has good group arrangement characteristics. The battery uses lithium ions as the main current carrier ions, the positive electrode material is lithium cobalt oxide, the negative electrode material is graphite, and the electrolyte is a liquid organic solvent system. The overall advantages are high energy density, high discharge rate and good low temperature performance. The battery consists of seven lithium-ion battery monomers connected in series, each with a capacity of 9.0Ah and an internal resistance of about 1.5mΩ.

[0024] In an extremely cold environment (-20°C), the internal resistance of the battery increases significantly and the voltage drops rapidly, causing the current to be unable to flow normally, thereby limiting the power output of the electric vehicle. To solve this problem, the present invention designs a system architecture based on direct resistance heating, constructs a charge and discharge circuit between the battery and the smoothing capacitor of the inverter, connects the positive pole of the battery to the three-phase motor U through the newly added relay SMR2, and controls the IGBT in the inverter to realize the step-up and step-down DC-DC circuit. In this process, the battery not only serves as an energy supply source, but also as a current channel, generating heat through its own internal resistance to achieve heating of the battery body, thereby quickly restoring its output performance. The coupling relationship formed between the battery and the three-phase motor windings, IGBTs, diodes and capacitors makes the battery a key node in the vehicle's electric heating system.

[0025] Furthermore, the inverter forms a buck-boost circuit by means of an insulated gate bipolar transistor and a capacitor, including: the inverter is a rectangular metal shell structure, and multiple power semiconductor devices are integrated inside, including an insulated gate bipolar transistor (IGBT) and a diode. The material of the inverter is silicon or silicon carbide, and it has high-voltage, high-frequency, and high-efficiency power conversion capabilities. The function of the inverter is to convert high-voltage direct current (DC) into three-phase alternating current (AC) to drive a three-phase motor to achieve power output. In addition to driving a three-phase motor, the inverter also assumes the function of a buck-boost DC-DC converter. Specifically, when the relay is closed, the IGBT device in the inverter controls its switching state to repeatedly charge and discharge the current between the battery and the smoothing capacitor of the inverter to form a circuit. This process relies on the alternating conduction and disconnection of the upper and lower bridge arm IGBTs of the V phase and the W phase and the corresponding diodes to achieve the voltage boost and voltage reduction process. This charge and discharge circuit not only causes a large current to flow through the battery to generate Joule heat, thereby heating the battery.

[0026] Furthermore, the three-phase motor participates in the construction of a DC buck-boost heating circuit as a current channel, including: the three-phase motor adopts a cylindrical shell structure, and a symmetrically arranged three-phase winding (U, V, W phase) is arranged inside it. The material of the three-phase motor is composed of a copper winding, an iron core and an aluminum alloy shell, and has high efficiency, low torque pulsation and good heat dissipation performance. The three-phase motor is driven to rotate by the three-phase alternating current provided by the inverter to achieve power output. The internal winding of the three-phase motor also participates in the construction of the heating circuit and becomes a component in the current path: when the relay SMR2 ​​is closed, the positive pole of the battery is connected to the three-phase motor U through the relay. At this time, the V and W phase windings of the three-phase motor work together with the IGBT and diode in the inverter to form a buck-boost DC-DC conversion circuit. During the charging stage, the current flows from the battery through the three-phase motor winding to the lower bridge arm IGBT of the inverter and is charged into the smoothing capacitor; during the discharging stage, the current in the capacitor returns to the battery through the upper bridge arm IGBT. During the whole process, the three-phase motor coils are repeatedly turned on and store energy, and the current flowing through them generates heat, which not only heats the windings of the three-phase motor itself, but also preheats peripheral components such as transmission oil and coolant through heat conduction.

[0027] Furthermore, the relay SMR2 ​​constructs a battery and inverter heating circuit by controlling the on-off of the circuit, including: the relay SMR2 ​​has a rectangular packaging structure, the shell is made of insulating flame-retardant material, and the interior is a silver alloy contact and a copper conductive structure. The relay SMR2 ​​is installed between the positive terminal of the battery and the U phase of the three-phase motor, as a switch device for controlling the on-off of the heating circuit. Its function is to be driven to close by the control unit when the ambient temperature is lower than the set value, so as to connect the battery with the three-phase motor coil and the buck-boost DC-DC conversion circuit composed of the inverter. Its working mechanism is that in the closed state, the battery current is allowed to flow into the U phase coil, and then enter the lower bridge arm of the IGBT in the inverter through the V phase and W phase windings, forming a bidirectional controllable electric energy circuit during the charge and discharge control process. The current in this circuit repeatedly flows between the battery and the smoothing capacitor, and heat is generated by the internal resistance of the battery and the coil impedance to achieve heating of the battery body and surrounding components.

[0028] Furthermore, the acquisition terminal collects operating parameters in real time and links with the controller, including: the acquisition terminal adopts a board-mounted module design, a rectangular flat structure, and its shell adopts a high temperature resistant and electromagnetic interference resistant plastic package. The acquisition terminal collects multiple data in real time, including battery internal resistance, battery temperature and smoothing capacitor voltage, and transmits the data to the upper control unit.

[0029] In this embodiment, the battery heating system based on extreme cold environment further includes an electric energy meter, which measures feedback data during the charging and discharging process, including: the electric energy meter is a modular matrix structure, encapsulated in a flame-retardant plastic shell, and its internal core components are composed of a voltage sampling module, a current sensor, an A / D converter and a digital processing chip. The electric energy meter collects real-time voltage and current data on the battery side and the capacitor side, and calculates the current integral and the voltage product to obtain the electric energy consumption per unit time.

[0030] Furthermore, in the battery heating system, the positive electrode of the battery is connected to the U phase of the three-phase motor through the relay SMR2. When the heating condition is met and the ambient temperature is lower than the set value, the control unit issues a closing command, the relay SMR2 ​​is connected, and the U phase conducts the current path. At the same time, the two windings of the V phase and the W phase in the inverter constitute the main current channel, and the IGBT devices (V- and W-) of the lower bridge arm of the inverter are alternately turned on under the control of the PWM signal of the controller, so that the current flows from the battery through the three-phase motor winding into the inverter.

[0031] During the charging stage, the controller turns on the lower IGBTs of the V-phase and W-phase in the inverter (i.e., V- and W-). The current starts from the positive electrode of the battery, first enters the U-phase of the three-phase motor through the relay SMR2, then passes through the V-phase and W-phase windings, flows into the lower bridge arm IGBT in the on state, and finally returns to the negative electrode of the battery, forming a preliminary closed current path. At this stage, the three-phase motor winding is equivalent to an energy storage inductor element, which stores magnetic energy during the flow of current. Subsequently, when V- and W- are controlled to be turned off, since the current in the inductor cannot change suddenly, the magnetic energy accumulated in the winding will be quickly released through the self-inductance of the three-phase motor winding. At this time, the current will "reroute" to flow through the diodes of the upper bridge arms of the V-phase and W-phase of the inverter, and then injected into the smoothing capacitor connected in parallel with the inverter, thereby charging the capacitor.

[0032] In the discharge stage, the controller turns on the V-phase and W-phase upper bridge arm IGBTs (i.e., V+ and W+) in the inverter. At this time, the smoothing capacitor serves as a power source, and its high voltage end is connected to the V-phase and W-phase windings of the three-phase motor through the turned-on upper side IGBT, and then the current is transmitted back to the battery through the battery circuit previously connected to the U-phase of the three-phase motor. In this process, the direction of the current is opposite to that in the charging stage, flowing from the smoothing capacitor to the battery, the capacitor begins to release the charge, and the voltage drops accordingly, realizing the step-down process in the DC-DC circuit. When the V+ and W+ upper bridge arm IGBTs are turned off, the current will not be interrupted immediately, because the three-phase motor windings have a certain inductance, and will maintain the current flow trend when the current changes. At this time, the current will automatically "turn" through the diode path of the V-phase and W-phase lower bridge arms in the inverter to continue to flow back to the negative electrode of the battery, completing the complete energy feedback path.

[0033] Furthermore, based on the battery, inverter, three-phase motor, acquisition terminal and relay, the control unit optimizes the IGBT switching frequency based on the operating data detected by the acquisition terminal to ensure that the battery heating system is quickly heated from -20°C to 0°C within 5 minutes. The specific steps are as follows: S1, after the battery heating system is powered on, the control unit loads the default initial operating parameters for trial operation, including: IGBT switching frequency f_init = 50Hz, PWM duty cycle D_init = 90%, control period T_ctrl = 500ms, heating parameters updated every 500ms, target battery temperature T_target = 0℃, heating duration T_total = 5 minutes; at this time, the acquisition terminal collects the following operating parameters in real time: battery voltage , smoothing capacitor voltage , smoothing capacitor current , battery current , Battery temperature , Battery internal resistance .

[0034] S2, at the initial frequency, the system starts to control the inverter to charge and discharge. In the charging stage: turn on the V- and W- lower bridge arm IGBTs, the battery charges the capacitor through the three-phase motor winding, the smoothing capacitor voltage rises to 600V, the battery current flows, and the acquisition terminal records the current peak and RMS value; in the discharging stage: turn on the V+ and W+ upper bridge arm IGBTs, the capacitor discharges the battery, the smoothing capacitor voltage drops to 300V, the current flows through the battery in the reverse direction, and continues to heat up; after completing a control cycle, the control unit obtains the following feedback data: the lowest voltage of the battery during the charging process , battery current RMS value , the heat generated by the battery per unit time , Instantaneous active power on the battery side and thermal efficiency , satisfy .

[0035] S3, based on the feedback data obtained in S2, if the battery has a minimum voltage during charging When the voltage is lower than the preset lower limit of 17.5V, the system determines that the single-cycle current corresponding to the frequency has an over-discharge risk, and the control unit will The difference between the preset voltage lower limit is calculated. When the difference ΔV is If the frequency is within the range, it is determined that the frequency needs to be increased immediately. The frequency increase strategy adopts a fixed step size method, increasing by 10Hz each time until , that is, the minimum battery voltage returns to the safe range and stops increasing the frequency; if the acquisition terminal detects the battery current RMS value for two consecutive control cycles Less than 50A, and the battery temperature The temperature rise rate is less than 0.2℃ / min, indicating that the single-cycle current amplitude and energy transfer density under the current IGBT switching frequency are insufficient to generate enough heat to increase the battery temperature. At this time, the control logic of reducing the frequency and enhancing the charge and discharge energy per unit cycle are started, and the control unit performs the frequency reduction operation at a dynamic ratio. The calculation formula of the dynamic ratio is: ,in, is the new frequency, is the current frequency, is the RMS value of the battery current, is the frequency adjustment factor, the value range is [1,5]. When the frequency reduction operation is terminated.

[0036] S4, when the battery temperature , the system determines that the heating is completed. After the heating is completed, the control unit disconnects the relay SMR2, and the system returns to the standby state by default.

[0037] In this embodiment, see Figure 3 , shows the periodic PWM signal formed by controlling the on-time (Ton) and off-time (Toff) of V- and W-, thereby realizing the "boost process" of raising the battery voltage to the capacitor voltage. This waveform represents the periodic on and off of the switching device, which can control the current to flow between the three-phase motor winding and the capacitor to charge the capacitor. In each cycle, the longer the Ton, the more energy is transmitted, and the higher the capacitor voltage is finally formed.

[0038] In this embodiment, see Figure 4 The figure shows the temperature change curve of the battery after 5 minutes of direct resistance heating at an initial temperature of about -20°C. It can be observed that the overall battery temperature is on an upward trend, but due to the instantaneous current fluctuations and environmental heat loss caused by high-frequency charging and discharging, there are certain slight fluctuations in the battery temperature curve, and declines occur in some periods. This is a typical corresponding feature of actual working conditions. Finally, the battery temperature is close to 0°C after 5 minutes, achieving the goal of rapid heating.

[0039] The present invention uses the IGBT in the inverter to control the charge and discharge path of the current, and uses the internal resistance of the battery and the resistance of the three-phase motor winding to generate Joule heat, thereby quickly raising the battery temperature, effectively solving the problems of slow temperature rise and delayed response in the prior art. The battery heating system of the present invention has a compact structure and does not require the addition of complex heating devices, which reduces the integration cost of the system. At the same time, the control unit can intelligently adjust the IGBT frequency by real-time monitoring of the voltage, current and temperature status through the acquisition terminal and the electric energy meter, so as to increase the battery temperature from -20°C to 0°C within 5 minutes, and has a high energy efficiency adjustment capability and good environmental adaptability.

[0040] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0041] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An intelligent fusion terminal based on a battery heating system in an extremely cold environment, comprising a battery, a three-phase motor, a control unit and an inverter, characterized in that: It also includes a relay SMR2 ​​and a collection terminal; the relay SMR2 ​​is connected to the positive electrode of the battery and the U phase of the three-phase motor to control the IGBT in the inverter to realize the buck-boost DC-DC loop; the collection terminal collects operating parameters in real time; Based on the battery, inverter, three-phase motor, control unit and relay, combined with the data obtained by the acquisition terminal, the control unit optimizes the IGBT switching frequency so that the battery heating system can be quickly heated from -20°C to 0°C within 5 minutes. The specific steps are as follows: S1, after the battery heating system is powered on, the control unit loads default initial operating parameters for trial operation, at which time the collection terminal collects the operating parameters in real time; S2, the battery heating system starts the charge and discharge control at the initial frequency. After completing a control cycle, the control unit obtains the lowest voltage of the battery during the charging process. , battery current RMS value , the heat generated by the battery per unit time , Instantaneous active power on the battery side and thermal efficiency ; S3, if the battery reaches the lowest voltage during charging , and the difference ΔV is range, start the frequency increase strategy, each time increase 10Hz, until the voltage rises above 17.8V; if the battery current RMS value is , indicating insufficient heating, reduce the frequency according to the dynamic proportional method. Stop frequency reduction when S4, when the battery temperature , heating is completed and the relay is disconnected.

2. According to claim 1, the intelligent fusion terminal based on the battery heating system in an extremely cold environment is characterized in that In S2, the charge and discharge control includes a charging stage and a discharging stage. In the charging stage: turn on the V- and W- lower bridge arm IGBTs, the battery charges the capacitor through the three-phase motor winding, the smoothing capacitor voltage rises to 600V, the battery current flows, and the acquisition terminal records the current peak and root mean square value; in the discharging stage: turn on the V+ and W+ upper bridge arm IGBTs, the capacitor discharges the battery, the smoothing capacitor voltage drops back to 300V, the current flows through the battery in the reverse direction, and continues to generate heat.

3. The intelligent fusion terminal based on the battery heating system in an extremely cold environment according to claim 1 is characterized in that In S3, the frequency increase strategy adopts a fixed step size method, increasing by 10Hz each time until , that is, the minimum battery voltage returns to the safe range and the frequency increase stops.

4. The intelligent fusion terminal based on the battery heating system in an extremely cold environment according to claim 1, characterized in that: In S3, the calculation formula of the dynamic ratio method is: ,in, is the new frequency, is the current frequency, is the RMS value of the battery current, is the frequency adjustment factor, and its value range is [1,5].

5. The intelligent fusion terminal based on the battery heating system in an extremely cold environment according to claim 1, characterized in that: In S1, the control unit loads the default initial operating parameters for trial operation, including: IGBT switching frequency f_init=50Hz, PWM duty cycle D_init=90%, control period T_ctrl=500ms, heating parameters updated every 500ms, target battery temperature T_target=0℃, heating duration T_total=5 minutes; the operating parameters include: battery voltage , smoothing capacitor voltage , smoothing capacitor current , battery current , Battery temperature , Battery internal resistance At the same time, the energy meter starts recording: the instantaneous active power on the battery side , capacitor side power , cumulative consumption .

6. The intelligent fusion terminal based on the battery heating system in an extremely cold environment according to claim 1, characterized in that: The battery adopts a lithium-ion battery structure, consisting of seven lithium-ion battery cells connected in series, each cell has a capacity of 9.0Ah, an internal resistance of 1.5mΩ, a positive electrode material of lithium cobalt oxide, a negative electrode material of graphite, and an electrolyte of a liquid organic solvent system.

7. The intelligent fusion terminal based on the battery heating system in an extremely cold environment according to claim 1, characterized in that: The inverter is a rectangular metal shell structure, which integrates multiple power semiconductor devices, including IGBTs and diodes. It has the function of converting direct current into three-phase alternating current, and also serves as a step-up and step-down DC-DC converter.

8. The intelligent fusion terminal based on the battery heating system in an extremely cold environment according to claim 1, characterized in that: The three-phase motor adopts a cylindrical shell structure, with symmetrically arranged three-phase windings inside, and is composed of a copper winding, an iron core and an aluminum alloy shell. The three-phase motor is driven to rotate by three-phase alternating current to achieve power output.

9. The intelligent fusion terminal based on the battery heating system in an extremely cold environment according to claim 1, characterized in that: The battery is connected to a three-phase motor through a relay, the three-phase motor is connected to an inverter, the acquisition terminal is connected to the inverter and the battery respectively, and the electric energy meter is connected in series between the battery and the inverter.

10. An electric energy meter based on a battery heating system in an extremely cold environment, characterized in that: An intelligent fusion terminal based on a battery heating system in an extremely cold environment as described in any one of claims 1 to 9, wherein the electric energy meter records feedback data during the charging and discharging process, and the feedback data includes: the lowest voltage of the battery during the charging process , battery current RMS value , the heat generated by the battery per unit time , Instantaneous active power on the battery side and thermal efficiency , satisfy .

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