Heating method and heating device for car-car communication radio of heavy freight train

Abstract

The application discloses a kind of car-car communication radio heating method and heating device of heavy freight train, utilize inductive freewheeling characteristic and full-bridge inverter principle, pulse current is generated using battery energy for internal heating of battery;Using pulse width control mode controls the on-off of driving half-bridge, and then according to the duty cycle control current of heating circuit, add PID controller to realize the control of heating current.The application proposes scheme without external power supply, directly utilize the energy of heated battery itself for internal heating, and can realize the free adjustment of heating current, with the advantages of high heating efficiency, flexible adjustment, improve the low-temperature resistance of lithium ion battery.Capitalizing on parameter identification method, the maximum heating current allowed is calculated, while ensuring rapid preheating, to avoid overcharge and overdischarge problems.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery thermal management technology, and in particular to a heating method and heating device for a car-to-car communication radio of a heavy-duty freight train. Background Technology

[0002] When heavy-haul freight trains operate in low-temperature environments, the performance of lithium-ion batteries in communication radios deteriorates significantly, drastically reducing the radios' operating time and lowering the reliability of train-to-train communication. Therefore, when heavy-haul freight trains operate in cold environments, it is necessary to heat the lithium-ion batteries to their normal operating temperature range. In cold regions, finding a more efficient and energy-saving method to quickly heat lithium-ion batteries and extend the radio's operating time becomes a crucial issue for ensuring the reliability of train-to-train communication.

[0003] Currently, research on battery heating mainly falls into two categories: external heating and internal heating. External heating utilizes heat conduction, transferring heat from an external heat source to the battery pack via a heat transfer medium. However, this method suffers from low heat transfer efficiency, uneven heating temperature, and slow heating speed, resulting in less than ideal performance. In contrast, internal heating offers advantages such as high heating efficiency and uniform temperature distribution. It generates a large amount of heat by applying current inside the battery, and its heating effect is even better at low temperatures. However, existing internal heating technologies require an external power source to provide the heating current. For example, Chinese patent application CN202110481639.6 discloses "A Pulse Heating Method, Device, and Vehicle and Process for a Power Battery," and Chinese patent application CN202210211979.1 discloses "Low-Temperature Heating-Charging Integrated Topology and Control Method for Electric Vehicle Power Batteries." Both rely on external equipment, limiting their application scenarios and making battery preheating in low-temperature environments difficult. Summary of the Invention

[0004] To address the problems in the prior art, this invention provides a heating method and device for a car-to-car communication radio in heavy-haul freight trains. Based on the inverter principle and inductor freewheeling characteristics, it employs a circuit switching control mode and uses pulse width modulation (PWM) signals to control circuit mode switching, thereby forming a stable current in the inductor and generating pulsed AC current through the inverter characteristics to heat the battery. Furthermore, a negative feedback mechanism is incorporated, utilizing a PID controller to achieve closed-loop control of the heating current. During the heating process, an equivalent circuit model of the lithium-ion battery is established, and the battery model parameters are identified using the least squares method to detect the internal state of the battery. Further, an electro-thermal coupling model is established, and an unscented Kalman filter algorithm is used to estimate and predict the battery's temperature rise state, thereby obtaining the optimal heating current for heating the battery. This invention can quickly and efficiently heat lithium-ion batteries internally, reducing the cost of the thermal management system, improving the performance of lithium-ion batteries in low-temperature environments, and extending the lifespan of lithium-ion batteries. The development of this invention was partially supported by the Major Science and Technology Project of China Railway Signal & Communication Corporation [Project No.: 2300-K1200035].

[0005] In the first aspect, a heating method for a vehicle-to-vehicle communication radio of a heavy-duty freight train is provided, which is based on a heating circuit. The heating circuit includes an H-type circuit structure composed of two sets of MOSFET driving half-bridges connected to inductors. The two ends of the two sets of MOSFET driving half-bridges are respectively connected to the two ends of the battery being heated. The two sets of MOSFET driving half-bridges use a pair of complementary PWM (pulse width modulation) signals to adjust the duty cycle.

[0006] The heating method includes the following steps:

[0007] S1: Online parameter identification to obtain the battery's internal parameters at the current moment;

[0008] S2: Calculate the maximum allowable heating current based on the battery's internal parameters at the current moment;

[0009] S3: Use a PID controller to output a PWM signal duty cycle to control the heating circuit, and collect the inductor current in the heating circuit to feed back to the PID controller to form a current closed-loop regulation in order to track the maximum allowable heating current.

[0010] S4: Use a battery temperature observer based on unscented Kalman filtering to estimate the actual internal temperature of the heated battery;

[0011] S5: If the actual internal temperature reaches the target temperature, then end the heating process; if the actual internal temperature does not reach the target temperature, then return to step S1.

[0012] According to the first aspect, in one possible implementation, the heating circuit includes four MOSFETs and an inductor. Every two MOSFETs are connected in series to form a MOSFET driving half-bridge. The two MOSFET driving half-bridges are connected in the middle through an inductor to form an H-type circuit structure. The two MOSFET driving half-bridges are connected in parallel to the two ends of the battery being heated. The two MOSFET switches in each MOSFET driving half-bridge are complementary.

[0013] According to the first aspect, in one possible implementation, step S1 includes:

[0014] S11: Set the identification period, data recording depth, and sampling period; update the collected battery terminal voltage and inductor current.

[0015] S12: Set initial values ​​for parameter identification;

[0016] S13: Online parameter identification is achieved using the least squares method. The formula for parameter identification is as follows:

[0017]

[0018] Among them, U k For the collected terminal voltage of the heated battery, I k For the collected inductor current, u k =2q-1, where q is the duty cycle of the PWM signal; θ1~θ4 are the parameters to be identified; and the subscript k is the kth sampling time.

[0019] S14: Based on the parameters to be identified, the open-circuit voltage and equivalent internal resistance of the battery, as well as the equivalent lamp group and the inductance value in the heating circuit are derived. The derivation formulas are shown below:

[0020]

[0021] Where E is the open-circuit voltage of the battery, R e R is the equivalent internal resistance of the heating circuit. o L is the equivalent internal resistance of the battery, and L is the inductance value of the inductor in the heating circuit.

[0022] According to the first aspect, in one possible implementation, in step S2, the maximum allowable heating current is calculated using the following formula:

[0023]

[0024] Among them, i max To allow the maximum heating current, U max For the upper limit of safe voltage, U min The lower limit of the safe voltage, E is the open-circuit voltage of the battery, and R is the lower limit of the safe voltage. oThis is the equivalent internal resistance of the battery.

[0025] According to the first aspect, in one possible implementation, in step S3, the state equation for the inductor current and the duty cycle of the input PWM signal is as follows:

[0026]

[0027] Where E is the open-circuit voltage of the battery, R e R is the equivalent internal resistance of the heating circuit. o L is the equivalent internal resistance of the battery, and L is the inductance value of the inductor in the heating circuit. o i is the inductance value of the battery's equivalent inductance. L q represents the inductor current, t represents time, and q represents the duty cycle of the PWM signal.

[0028] Let u = 2q - 1, then the Laplace transfer function G(s) of the control variable u and the inductor current can be obtained as follows:

[0029]

[0030] Where s is the frequency domain conversion factor;

[0031] A PID controller is designed based on the transfer function, and a process is added to convert the control variable u into a PWM signal duty cycle q. Then, the heating circuit is controlled according to the PWM signal duty cycle q.

[0032] According to the first aspect, in one possible implementation, step S4 includes:

[0033] S41: Establish the electro-thermal coupling model of the battery, as follows:

[0034]

[0035] Where T is temperature, t is time, m, c, h, and S are the battery's mass, specific heat capacity, surface heat dissipation coefficient, and surface area, respectively. a Q represents the ambient temperature. j This refers to the internal heating power of the battery.

[0036] S42: Discretize the battery thermal model according to the sampling period to obtain the following form:

[0037]

[0038] Among them, t p To estimate the sampling period time for battery temperature, T n Q represents the temperature state at the time of the nth battery temperature estimation sampling period. j,n The internal heating power of the battery at the time of the sampling period for estimating the temperature of the nth battery;

[0039] S43: Use a Kalman filter to predict the battery temperature in advance based on the current state of the battery and calculate the prior error covariance value;

[0040] S44: Input the collected battery temperature, the battery temperature estimated by the Kalman filter, the current heating current, and the ambient temperature into the Kalman filter, calculate the Kalman gain, perform battery temperature state correction, obtain the actual internal temperature of the battery, and update the error covariance.

[0041] Secondly, a heating device for a car-to-car communication radio on a heavy-haul freight train is provided, comprising:

[0042] Heating circuit: It includes an H-type circuit structure consisting of two sets of MOSFET driving half-bridges connected to inductors. The two ends of the two sets of MOSFET driving half-bridges are respectively connected to the two ends of the battery being heated. The two sets of MOSFET driving half-bridges use a pair of complementary PWM signals to adjust the duty cycle.

[0043] Measurement system: used to collect ambient temperature, terminal voltage of the heated battery, surface temperature of the heated battery, and inductor current in the heating circuit in real time;

[0044] The control system, connected to the heating circuit and the measuring system, is configured to perform the steps of the heating method as described above.

[0045] According to the second aspect, in one possible implementation, the heating circuit includes four MOSFETs and an inductor. Every two MOSFETs are connected in series to form a MOSFET driving half-bridge. The two MOSFET driving half-bridges are connected in the middle through an inductor to form an H-type circuit structure. The two MOSFET driving half-bridges are connected in parallel across the two ends of the battery being heated. The two MOSFET switches in each MOSFET driving half-bridge are complementary. The battery being heated provides energy to the heating circuit and uses the current generated by the heating circuit for internal self-heating.

[0046] According to the second aspect, in one possible implementation, the measurement system includes:

[0047] Voltage sensor: used to collect the terminal voltage of the heated battery;

[0048] Current sensor: used to collect inductor current in heating circuits;

[0049] Temperature sensor: Used to collect ambient temperature and battery surface temperature.

[0050] According to the second aspect, in one possible implementation, the control system includes:

[0051] Computer: Used for online parameter identification, calculation of maximum allowable heating current, estimation of the actual internal temperature of the heated battery and comparison with the target temperature;

[0052] The bottom-level control unit receives the maximum allowable heating current calculated by the computer, performs closed-loop current regulation through a PID controller, and outputs a PWM signal duty cycle to the heating circuit to track the maximum allowable heating current.

[0053] The present invention provides a heating method and heating device for car-to-car communication radios in heavy-haul freight trains, which has the following beneficial effects:

[0054] This paper presents a low-temperature pulsed internal self-heating technology for vehicle-to-vehicle communication radios in heavy-duty freight trains, eliminating the need for an external power source. By modifying the heater topology and employing a reasonable control method, the technology utilizes the battery's own energy as a power supply to generate an adjustable pulsed current for internal heating of the lithium-ion battery. This pulsed current offers higher heating efficiency compared to other current waveforms, allows for flexible adjustment of the pulsed current amplitude, and overcomes topology limitations, achieving efficient and rapid battery heating. This avoids the drawbacks of external heating, such as lower heat transfer efficiency, longer heating times, and uneven cell heating temperatures. The circuit structure is simple, with fewer components, reducing the cost of electric vehicle thermal management systems. A negative feedback mechanism is incorporated, using a PID controller to achieve closed-loop control of the heating current. During the heating process, an equivalent circuit model of the lithium-ion battery is established, and the battery model parameters are identified using the least squares method to detect the battery's internal state. Furthermore, an electro-thermal coupling model is established, and an unscented Kalman filter algorithm is used to estimate and predict the battery's temperature rise state, providing a more accurate understanding of the lithium-ion battery's characteristics in low-temperature environments and facilitating the implementation of more precise heating strategies. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 This is a structural diagram of the heating circuit provided in an embodiment of the present invention;

[0057] Figure 2 This is a diagram showing the working modes of the heating circuit provided in an embodiment of the present invention, wherein (a) is a state diagram of mode 1 and (b) is a state diagram of mode 2.

[0058] Figure 3 This is a waveform diagram of the heating current during the heating process provided in an embodiment of the present invention;

[0059] Figure 4 This is a flowchart of the closed-loop feedback control of the PID controller provided in an embodiment of the present invention;

[0060] Figure 5 This is an overall flowchart of heating control provided in an embodiment of the present invention. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0062] This invention provides a heating method for a vehicle-to-vehicle communication radio on a heavy-haul freight train, which is based on a heating circuit. The heating circuit includes an H-type circuit structure consisting of two sets of MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) driving half-bridges connected to inductors. The two ends of each MOSFET driving half-bridge are respectively connected to the two ends of the battery being heated. The two MOSFET driving half-bridges use a pair of complementary PWM signals to adjust their duty cycles. More specifically, as shown... Figure 1 As shown, the heating circuit includes four MOSFETs (S1, S2, S3, S4) and one inductor L; D1 and D2 are PWM signals, and Re is the equivalent internal resistance of the heating circuit. S1 and S3 form one MOSFET driving half-bridge, and S2 and S4 form another. The MOSFET switches within each half-bridge are complementary, meaning only one switch can be closed while the other is open. The two sets of MOSFET driving half-bridges are connected by an inductor, forming an H-bridge structure. When the PWM signals D1 and D2 are complementary, due to the freewheeling characteristic of the inductor, a stable continuous current is generated across the inductor. Through the current inversion effect of the two sets of MOSFET driving half-bridges, an AC pulse current is ultimately formed on the battery.

[0063] The operating mode of the heating circuit is as follows: Figure 2 As shown, the heating circuit operates in two modes: Mode 1 and Mode 2. In Mode 1, MOSFET switches S1 and S4 are on, while switches S2 and S3 are off; if the inductor current direction is as follows... Figure 2 As shown in (a), the pulse current flows out from the positive terminal of the battery. In mode 2, MOSFET switches S1 and S4 are open, and switches S2 and S3 are open; at this time, the pulse current flows into the positive terminal of the battery. Therefore, when the heating circuit is controlled using complementary PWM signals, an alternating current is generated on the battery. In this embodiment, the heating current waveform is as follows: Figure 3As shown. When the heating circuit is controlled by a PWM signal, an approximate DC current will be generated on the inductor. The current amplitude will vary depending on the duty cycle, and a pulsed AC current will be generated on the battery.

[0064] Based on the heating circuit described above, the heating method provided in this embodiment is as follows: Figure 5 As shown, it includes the following steps:

[0065] S0: Start heating and set the target temperature.

[0066] S1: Online parameter identification, obtaining the battery's internal parameters at the current moment. Specifically, this includes:

[0067] S11: Set the identification period, data recording depth, and sampling period. In this embodiment, the sampling period is set to 1ms, the data recording depth is 200, and the identification period is 100ms. Update the collected battery terminal voltage and inductor current.

[0068] S12: Set initial values ​​for parameter identification;

[0069] S13: Online parameter identification is achieved using the least squares method. The formula for parameter identification is as follows:

[0070]

[0071] Among them, U k For the collected terminal voltage of the heated battery, I k For the collected inductor current, u k =2q-1, where q is the duty cycle of the PWM signal; θ1~θ4 are the parameters to be identified; and the subscript k is the kth sampling time.

[0072] S14: Based on the parameters to be identified, the open-circuit voltage and equivalent internal resistance of the battery, as well as the equivalent lamp group and the inductance value in the heating circuit are derived. The derivation formulas are shown below:

[0073]

[0074] Where E is the open-circuit voltage of the battery, R e R is the equivalent internal resistance of the heating circuit. o L is the equivalent internal resistance of the battery, and L is the inductance value of the inductor in the heating circuit.

[0075] S2: Calculate the maximum allowable heating current based on the battery's internal parameters at the current moment, and use it as a control reference.

[0076] The maximum allowable heating current is calculated using the following formula:

[0077]

[0078] Among them, i max To allow the maximum heating current, U max For the upper limit of safe voltage, U min The lower limit of the safe voltage, E is the open-circuit voltage of the battery, and R is the lower limit of the safe voltage. o This represents the battery's equivalent internal resistance. A safe voltage limit prevents overcharging and over-discharging, enabling rapid battery heating while ensuring battery safety.

[0079] S3: A PID controller is used to control the heating circuit by outputting a PWM signal duty cycle. The inductor current in the heating circuit is collected and fed back to the PID controller to form a current closed-loop regulation to track the maximum allowable heating current. The PWM signal duty cycle and the inductor current constitute a first-order inertial system.

[0080] Specifically, inductor current is selected as the signal acquisition quantity. In this embodiment, the sampling period is set to 1ms. The PID controller forms a current closed-loop regulation based on the acquired inductor current to improve control accuracy. Based on the characteristics of the heating circuit, the state equation of inductor current and the duty cycle of the input PWM signal is obtained as follows:

[0081]

[0082] Where E is the open-circuit voltage of the battery, R e R is the equivalent internal resistance of the heating circuit. o L is the equivalent internal resistance of the battery, and L is the inductance value of the inductor in the heating circuit. o i is the inductance value of the battery's equivalent inductance. L q represents the inductor current, t represents time, and q represents the duty cycle of the PWM signal.

[0083] Let u = 2q - 1, then the Laplace transfer function G(s) of the control variable u and the inductor current can be obtained as follows:

[0084]

[0085] Where s is the frequency domain conversion factor;

[0086] A PID controller is designed based on the transfer function, incorporating a process of converting the control variable u into a PWM signal duty cycle q. The heating circuit is then controlled based on the PWM signal duty cycle q. The closed-loop feedback control flowchart of the PID controller is shown below. Figure 4 As shown.

[0087] S4: Estimate the actual internal temperature of the heated battery using a battery temperature observer based on an unscented Kalman filter. Specifically, this includes:

[0088] S41: Establish the electro-thermal coupling model of the battery, as follows:

[0089]

[0090] Where T is temperature, t is time, m, c, h, and S are the battery's mass, specific heat capacity, surface heat dissipation coefficient, and surface area, respectively. a Q represents the ambient temperature. j This refers to the internal heating power of the battery.

[0091] S42: Discretize the battery thermal model according to the sampling period to obtain the following form:

[0092]

[0093] Among them, t p To estimate the sampling period time for battery temperature, T n Q represents the temperature state at the time of the nth battery temperature estimation sampling period. j,n The internal heating power of the battery at the time of the sampling period for estimating the temperature of the nth battery;

[0094] S43: Use a Kalman filter to predict the battery temperature in advance based on the current state of the battery and calculate the prior error covariance value;

[0095] S44: Input the collected battery temperature, the battery temperature estimated by the Kalman filter, the current heating current, and the ambient temperature into the Kalman filter, calculate the Kalman gain, perform battery temperature state correction, obtain the actual internal temperature of the battery, and update the error covariance.

[0096] S5: If the actual internal temperature reaches the target temperature, then end the heating process; if the actual internal temperature does not reach the target temperature, then return to step S1.

[0097] This invention also provides a heating device for a car-to-car communication radio on a heavy-haul freight train, comprising:

[0098] Heating circuit: It includes an H-type circuit structure consisting of two sets of MOSFET driving half-bridges connected to inductors. The two ends of the two sets of MOSFET driving half-bridges are respectively connected to the two ends of the battery being heated. The duty cycle of the two sets of MOSFET driving half-bridges is adjusted by a pair of complementary PWM signals. The two MOSFET switches in each set of MOSFET driving half-bridges are complementary. The battery being heated provides energy to the heating circuit and uses the current generated by the heating circuit for internal self-heating.

[0099] Measurement system: used to collect ambient temperature, terminal voltage of the heated battery, surface temperature of the heated battery, and inductor current in the heating circuit in real time;

[0100] The control system, connected to the heating circuit and the measuring system, is configured to perform the steps of the heating method as described above.

[0101] Specifically, the heating circuit includes four MOSFETs and one inductor. Every two MOSFETs are connected in series to form a MOSFET driving half-bridge. The two MOSFET driving half-bridges are connected in the middle through the inductor to form an H-type circuit structure. The two MOSFET driving half-bridges are connected in parallel across the two ends of the battery being heated. The two MOSFET switches in each MOSFET driving half-bridge are complementary. The battery being heated provides energy to the heating circuit and uses the current generated by the heating circuit for internal self-heating.

[0102] In this embodiment, the measurement system includes:

[0103] Voltage sensor: used to collect the terminal voltage of the heated battery;

[0104] Current sensor: used to collect inductor current in heating circuits;

[0105] Temperature sensor: Used to collect ambient temperature and battery surface temperature.

[0106] In this embodiment, the control system includes:

[0107] Computer: Used for online parameter identification, calculation of maximum allowable heating current, estimation of the actual internal temperature of the heated battery and comparison with the target temperature;

[0108] The underlying control unit, implemented based on the STM32F407 microcontroller, receives the maximum allowable heating current calculated by the computer, performs closed-loop current regulation through a PID controller, and outputs a PWM signal duty cycle to the heating circuit to track the maximum allowable heating current.

[0109] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0110] This invention provides a heating method and device for a vehicle-to-vehicle communication radio in heavy-duty freight trains. It is a low-temperature pulsed internal self-heating technology for the vehicle-to-vehicle communication radio of heavy-duty freight trains that requires no external power supply. Through heater topology modification and a reasonable control method, it utilizes the battery's own energy as a power source to generate an adjustable pulsed current for internal heating of the lithium-ion battery. The pulsed current has higher heating efficiency compared to other current waveforms, and its amplitude can be flexibly adjusted, overcoming topology limitations to achieve efficient and rapid battery heating. This avoids the disadvantages of external heating, such as lower heat transfer efficiency, relatively long heating time, and uneven battery cell heating temperatures. The circuit structure is simple, with fewer circuit components, reducing the cost of the electric vehicle thermal management system. A negative feedback mechanism is incorporated, using a PID controller to achieve closed-loop control of the heating current. During the heating process, an equivalent circuit model of the lithium-ion battery is established, and the battery model parameters are identified using the least squares method to detect the internal state of the battery. Furthermore, an electro-thermal coupling model is established, and an unscented Kalman filter algorithm is used to estimate and predict the battery's temperature rise state, providing a more accurate understanding of the characteristics of lithium-ion batteries in low-temperature environments, which is beneficial for implementing more accurate heating strategies.

[0111] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for heating a car-to-car communication radio on a heavy-haul freight train, characterized in that, The heating circuit is based on a heating circuit, which includes an H-type circuit structure consisting of two sets of MOSFET driving half-bridges connected to an inductor. The two ends of the two sets of MOSFET driving half-bridges are respectively connected to the two ends of the battery being heated. The two sets of MOSFET driving half-bridges use a pair of complementary PWM signals to adjust the duty cycle. The heating method includes the following steps: S1: Online parameter identification to obtain the battery's internal parameters at the current moment; S2: Calculate the maximum allowable heating current based on the battery's internal parameters at the current moment; S3: Use a PID controller to output a PWM signal duty cycle to control the heating circuit, and collect the inductor current in the heating circuit to feed back to the PID controller to form a current closed-loop regulation in order to track the maximum allowable heating current. S4: Use a battery temperature observer based on unscented Kalman filtering to estimate the actual internal temperature of the heated battery; S5: If the actual internal temperature reaches the target temperature, then heating will end; If the actual internal temperature does not reach the target temperature, return to step S1; Step S1 includes: S11: Set the identification period, data recording depth, and sampling period; update the collected battery terminal voltage and inductor current. S12: Set initial values ​​for parameter identification; S13: Online parameter identification is achieved using the least squares method. The formula for parameter identification is as follows: in, U k The collected data is the terminal voltage of the heated battery. I k For the collected inductor current, u k =2 q -1, q This refers to the duty cycle of the PWM signal. θ 1~ θ 4 represents the parameter to be identified; subscript k For the first k Each sampling time; S14: Based on the parameters to be identified, the open-circuit voltage and equivalent internal resistance of the battery, as well as the equivalent lamp group and the inductance value in the heating circuit are derived. The derivation formulas are shown below: in, E This is the open-circuit voltage of the battery. R e This is the equivalent internal resistance of the heating circuit. R o This is the equivalent internal resistance of the battery. L The inductance value is the value of the inductor in the heating circuit; Step S4 includes: S41: Establish the electro-thermal coupling model of the battery, as follows: in, T It is temperature ，t For time ，m , c , h , S These are the battery's mass, specific heat capacity, surface heat dissipation coefficient, and surface area. T a For ambient temperature, Q j This refers to the internal heating power of the battery. S42: Discretize the battery thermal model according to the sampling period to obtain the following form: in, t p To estimate the sampling period time for battery temperature, T n For the first n The battery temperature is estimated at the temperature state at any point during the sampling period. For the first n Battery internal heating power at the time of the battery temperature estimation sampling period; S43: Use a Kalman filter to predict the battery temperature in advance based on the current state of the battery and calculate the prior error covariance value; S44: Input the collected battery temperature, the battery temperature estimated by the Kalman filter, the current heating current, and the ambient temperature into the Kalman filter, calculate the Kalman gain, perform battery temperature state correction, obtain the actual internal temperature of the battery, and update the error covariance.

2. The method for heating the car-to-car communication radio of a heavy-haul freight train according to claim 1, characterized in that, The heating circuit includes four MOSFETs and one inductor. Every two MOSFETs are connected in series to form a MOSFET driving half-bridge. The two MOSFET driving half-bridges are connected in the middle through an inductor to form an H-type circuit structure. The two MOSFET driving half-bridges are connected in parallel to the two ends of the battery being heated. The two MOSFET switches in each MOSFET driving half-bridge are complementary.

3. The method for heating the car-to-car communication radio of a heavy-haul freight train according to claim 1, characterized in that, In step S2, the maximum allowable heating current is calculated using the following formula: in, To allow the maximum heating current, For the upper limit of safe voltage, The lower limit of safe voltage. E This is the open-circuit voltage of the battery. R o This is the equivalent internal resistance of the battery.

4. The method for heating the car-to-car communication radio of a heavy-haul freight train according to claim 1, characterized in that, In step S3, the state equations for the inductor current and the duty cycle of the input PWM signal are as follows: in, E This is the open-circuit voltage of the battery. R e This is the equivalent internal resistance of the heating circuit. R o This is the equivalent internal resistance of the battery. L The inductance value in the heating circuit. L o The inductance value is the equivalent inductance of the battery. Let t be the inductor current and t be time. q This refers to the duty cycle of the PWM signal. make u =2 q -1 can be used to obtain the control variable. u Laplace transfer function of inductor current G ( s )as follows: Where s is the frequency domain conversion factor; Design a PID controller based on the transfer function, and incorporate the control variable... u Convert to PWM signal duty cycle q The process, and then based on the duty cycle of the PWM signal. q Control the heating circuit.

5. A heating device for a car-to-car communication radio on a heavy-haul freight train, characterized in that, A method for heating a car-to-car communication radio for heavy-haul freight trains as described in any one of claims 1 to 4, comprising: Heating circuit: It includes an H-type circuit structure consisting of two sets of MOSFET driving half-bridges connected to inductors. The two ends of the two sets of MOSFET driving half-bridges are respectively connected to the two ends of the battery being heated. The two sets of MOSFET driving half-bridges use a pair of complementary PWM signals to adjust the duty cycle. Measurement system: used to collect ambient temperature, terminal voltage of the heated battery, surface temperature of the heated battery, and inductor current in the heating circuit in real time; The control system, connected to the heating circuit and the measuring system, is configured to perform the steps of the heating method as described in claim 1.

6. The heating device for the car-to-car communication radio of a heavy-haul freight train according to claim 5, characterized in that, The heating circuit includes four MOSFETs and one inductor. Every two MOSFETs are connected in series to form a MOSFET driving half-bridge. The two MOSFET driving half-bridges are connected in the middle through the inductor to form an H-type circuit structure. The two MOSFET driving half-bridges are connected in parallel to the two ends of the battery being heated. The two MOSFET switches in each MOSFET driving half-bridge are complementary. The battery being heated provides energy to the heating circuit and uses the current generated by the heating circuit for internal self-heating.

7. The heating device for the car-to-car communication radio of a heavy-haul freight train according to claim 5, characterized in that, The measurement system includes: Voltage sensor: used to collect the terminal voltage of the heated battery; Current sensor: used to collect inductor current in heating circuits; Temperature sensor: Used to collect ambient temperature and battery surface temperature.

8. The heating device for the car-to-car communication radio of a heavy-haul freight train according to claim 5, characterized in that, The control system includes: Computer: Used for online parameter identification, calculation of maximum allowable heating current, estimation of the actual internal temperature of the heated battery and comparison with the target temperature; The bottom-level control unit receives the maximum allowable heating current calculated by the computer, performs closed-loop current regulation through a PID controller, and outputs a PWM signal duty cycle to the heating circuit to track the maximum allowable heating current.

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