Battery thermal management system based on PWM (Pulse Width Modulation) voltage regulation thermoelectric refrigerating unit

Abstract

The invention discloses a battery thermal management system based on a PWM (Pulse Width Modulation) voltage regulation thermoelectric refrigerating unit, which relates to the field of lithium battery thermal management and comprises a thermoelectric refrigerating unit system and an air cooling system, the air cooling system provides cooling capacity by taking air as a refrigerant; the thermoelectric refrigerating unit system comprises a lithium battery pack, an adjustable voltage power supply, a positive and negative rotation PWM voltage regulator, a semiconductor thermoelectric refrigerating unit and a digital controller which are electrically connected in sequence; the adjustable voltage power supply is used for adjusting output voltage according to the voltage regulation and control signal and providing driving electric energy for the positive and negative rotation PWM voltage regulator; the positive and negative rotation PWM voltage regulator outputs high-voltage pulse or PWM driving voltage to the semiconductor thermoelectric refrigerating unit to drive the semiconductor thermoelectric refrigerating unit to refrigerate or heat; the digital controller sends out a voltage regulation and control signal, a power switch signal and a positive and negative rotation signal according to a battery temperature measurement signal and an environment temperature. The cooling system is high in cooling efficiency and stable in cooling effect, and safe and stable operation of the vehicle-mounted battery can be effectively guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery thermal management, and more specifically, to a battery thermal management system based on a PWM voltage-regulating thermoelectric cooler. Background Art

[0002] As a core energy component in new energy vehicles and energy storage systems, the working performance, cycle life, and operating efficiency of lithium-ion batteries are deeply affected by the ambient temperature.

[0003] Currently, the mainstream thermal management methods for lithium battery vehicles include air cooling, liquid cooling, phase change material cooling, and air source heat pumps. These methods have their own advantages and disadvantages. Among them, although the air cooling system has a simple structure and low cost, its cooling efficiency is low and there are noise problems; liquid cooling removes the heat generated by the battery through the circulation of the coolant. Although it has high cooling efficiency and can precisely control the battery temperature, the system structure is relatively complex, the cost is high, and there is a risk of liquid leakage; phase change material cooling utilizes the absorption and release of heat during the phase change process of the material. Although it has the advantages of simple structure and large heat capacity, it is easily affected by supercooling phenomena, the cooling effect is unstable, and it is difficult to be widely promoted in high-power applications; air source heat pumps achieve heat transfer through the phase change cycle of the working medium and can realize the dual functions of refrigeration and heating by changing the flow direction of the working medium. However, their performance is still unstable under extreme climate conditions, especially in extremely cold or hot environments, and additional heat insulation and auxiliary systems are required to improve the operating effect.

[0004] Therefore, how to provide a cooling system with high cooling efficiency and stable cooling effect is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a battery thermal management system based on a PWM voltage-regulating thermoelectric cooler, which integrates a thermoelectric cooler and an air cooling system. By installing the thermoelectric cooler on both sides of the battery module and equipping it with a heat sink, and cooperating with the air cooling system with air as the cooling medium, efficient thermal management is achieved.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention discloses a battery thermal management system based on a PWM voltage-regulating thermoelectric cooler, comprising: a thermoelectric cooler system and an air cooling system;

[0008] The air cooling system uses air as the refrigerant to provide cooling capacity for the lithium battery pack;

[0009] The thermoelectric cooler system includes: a lithium battery pack, an adjustable voltage power supply, a forward and reverse PWM voltage regulator, a semiconductor thermoelectric cooler that are electrically connected in sequence, and a digital controller that is signal-connected to temperature sensors on the adjustable voltage power supply, the forward and reverse PWM voltage regulator, and the lithium battery pack respectively;

[0010] The adjustable voltage power supply is powered by the input of the lithium battery pack, and adjusts the output voltage according to the voltage regulation signal of the digital controller to provide driving electrical energy to the forward and reverse PWM voltage regulator;

[0011] The forward and reverse PWM voltage regulator outputs a high-voltage pulse or a PWM driving voltage to the semiconductor thermoelectric cooler according to the input voltage of the adjustable voltage power supply, as well as the power switch signal and the forward and reverse signal of the digital controller;

[0012] The semiconductor thermoelectric cooler is arranged on both sides of the lithium battery pack, and cools or heats according to the high-voltage pulse or the PWM driving voltage, so that the lithium battery pack is within the designed operating temperature range;

[0013] The digital controller issues the voltage regulation signal, the power switch signal, and the forward and reverse signal according to the temperature measurement signal of the temperature sensor and the ambient temperature.

[0014] Furthermore, the battery thermal management system monitors the battery temperature and the ambient temperature, and executes a pulse cooling mode, a continuous cooling mode, an idle mode, a continuous heating mode, or a pulse heating mode;

[0015] When the battery temperature rises abnormally or there is a tendency of local thermal runaway, the system executes the pulse cooling mode;

[0016] When the battery temperature is higher than the battery temperature threshold, or the ambient temperature is greater than or equal to the first ambient temperature threshold, the system executes the continuous cooling mode;

[0017] When the battery temperature is lower than the battery temperature threshold, and the ambient temperature is less than the first ambient temperature threshold and greater than or equal to the second ambient temperature threshold, the system executes the idle mode;

[0018] When the battery temperature is lower than the battery temperature threshold, and the ambient temperature is less than the second ambient temperature threshold and greater than or equal to the third ambient temperature threshold, the system executes the continuous heating mode;

[0019] When the battery temperature is lower than the battery temperature threshold, and the ambient temperature is less than the third ambient temperature threshold, the system executes the pulse heating mode.

[0020] Further, when the pulse refrigeration mode is executed, the digital controller controls the adjustable voltage power supply to output a high voltage through the voltage regulation signal, sets the forward and reverse signal to 1, and controls the forward and reverse PWM voltage regulator to emit high-voltage pulses with a set continuous duration at fixed time intervals through the power switch signal; under the drive of the high-voltage pulses, the thermoelectric cooler enters a rapid refrigeration state, realizing transient rapid refrigeration of the lithium battery pack.

[0021] Further, when the continuous refrigeration mode is executed, the digital controller controls the adjustable voltage power supply to output a rated voltage through the voltage regulation signal, sets the forward and reverse signal to 1, and controls the duty cycle of the forward and reverse PWM voltage regulator through the power switch signal, thereby controlling the refrigeration power of the thermoelectric cooler; the digital controller also controls the air cooling system to work in coordination with the thermoelectric cooler to dissipate heat from the lithium battery pack through the fan power signal.

[0022] Further, when the idle mode is executed, the digital controller stops sending control signals to the adjustable voltage power supply and the forward and reverse PWM voltage regulator, and only controls the air cooling system to dissipate heat from the lithium battery pack through the fan power signal.

[0023] Further, when the continuous heating mode is executed, the digital controller controls the adjustable voltage power supply to output a rated voltage through the voltage regulation signal, sets the forward and reverse signal to 0, and controls the duty cycle of the forward and reverse PWM voltage regulator through the power switch signal, thereby controlling the heating power of the thermoelectric cooler to heat the lithium battery pack.

[0024] Further, when the pulse heating mode is executed, the digital controller controls the adjustable voltage power supply to output a high voltage through the voltage regulation signal, sets the forward and reverse signal to 0, and controls the forward and reverse PWM voltage regulator to emit high-voltage pulses with a set continuous duration at fixed time intervals through the power switch signal; under the drive of the high-voltage pulses, the thermoelectric cooler enters a rapid heating state, realizing rapid temperature increase of the lithium battery pack.

[0025] Further, the parameters of the high-voltage pulses are determined by the following method:

[0026] First, according to the mass m, specific heat capacity c, and target temperature drop ΔT of the lithium battery pack, calculate the heat to be transferred, and the formula is ΔQ = m·c·ΔT;

[0027] Then, according to the instantaneous refrigeration power PTEC of the thermoelectric cooler and the heat dissipation power Pair of the air cooling system, determine the pulse duration, and the formula is: Δt = ΔQ / (PTEC + Pair);

[0028] Finally, based on the rated voltage Vbase of the thermoelectric cooler and the transient supercooling demand k, the pulse voltage is set, and the formula is: Vpulse = k·Vbase, where 2 ≤ k ≤ 5.

[0029] Furthermore, the designed operating temperature range is from 25°C to 35°C.

[0030] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a battery thermal management system based on a PWM voltage-regulated thermoelectric cooler. By combining the thermoelectric cooler with the air-cooling system and switching between multiple operating modes, the impact of the external environment on lithium batteries is effectively reduced, and the significant attenuation of battery capacity at low temperatures (-15°C) and the risk of thermal runaway caused by high temperatures (≥40°C) are reduced. The efficient control of battery temperature from extremely cold to high-temperature environments is achieved; by combining pulse and continuous operating modes, the energy consumption is significantly reduced during battery preheating and cooling, especially when restarting after long-term parking (≥10 hours), the required energy consumption can be reduced, which is of great significance for improving the energy utilization efficiency of vehicles; the system can flexibly adjust parameters such as fan power, thermoelectric cooler voltage, pulse current amplitude and time according to the operating conditions of lithium batteries and the external environment, achieving a balance between heat dissipation and energy consumption, maximizing energy efficiency. At the same time, when the local temperature of the battery is too high, the pulsed TEC mode can achieve rapid cooling, reducing the risk of thermal runaway propagation, ensuring system safety, and reducing economic losses and threats to personal safety. The present invention provides a cooling system with high cooling efficiency and stable cooling effect, which can effectively ensure the safe and stable operation of in-vehicle batteries. Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to the provided drawings.

[0032] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention.

[0033] Figure 2 It is a schematic diagram of the trend of the classical voltage input to the semiconductor thermoelectric cooler under different operating modes of an embodiment of the present invention.

[0034] In the figure, 1. Adjustable voltage power supply; 2. Forward and reverse PWM voltage regulator; 3. Digital controller; 4. Semiconductor thermoelectric cooler; 5. Lithium battery pack; 6. Power switch signal; 7. Forward and reverse signal; 8. Voltage regulation signal; 9. Temperature measurement signal. Detailed Embodiments

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] An embodiment of the present invention discloses a battery thermal management system based on a PWM voltage-regulated thermoelectric cooler, as Figure 1 shown, including: a thermoelectric cooler system and an air-cooling system (not shown in the figure);

[0037] The air-cooling system uses air as a refrigerant to provide cooling capacity for the lithium battery pack 5;

[0038] The thermoelectric cooler system includes: a lithium battery pack 5, an adjustable voltage power supply 1, a forward and reverse PWM voltage regulator 2, a semiconductor thermoelectric cooler 4 that are electrically connected in sequence, and a digital controller 3 that is respectively signal-connected to the temperature sensors on the adjustable voltage power supply 1, the forward and reverse PWM voltage regulator 2, and the lithium battery pack 5;

[0039] The adjustable voltage power supply 1 is powered by the input of the lithium battery pack 5, and adjusts the output voltage according to the voltage regulation signal 8 of the digital controller 3 to provide driving electric energy for the forward and reverse PWM voltage regulator 2;

[0040] The forward and reverse PWM voltage regulator 2 outputs a high-voltage pulse or a PWM driving voltage to the semiconductor thermoelectric cooler 4 according to the input voltage of the adjustable voltage power supply 1, and the power switch signal 6 and the forward and reverse signal 7 of the digital controller 3;

[0041] The semiconductor thermoelectric cooler 4 is arranged on both sides of the lithium battery pack 5, and cools or heats according to the high-voltage pulse or the PWM driving voltage, so that the lithium battery pack 5 is within the designed operating temperature range;

[0042] The digital controller 3 issues a voltage regulation signal 8, a power switch signal 6, and a forward and reverse signal 7 according to the temperature measurement signal 9 of the temperature sensor and the ambient temperature.

[0043] Specifically, as a new and efficient thermal management technology for vehicle-mounted lithium batteries, the thermoelectric cooler (TEC) provides a temperature control solution with high efficiency, no pollution, and strong reliability, especially suitable for scenarios with high requirements for temperature control accuracy. Its working principle is based on the Peltier effect, that is, when a direct current passes through a thermocouple composed of P-type and N-type semiconductor materials, heat absorption and release will occur at both ends of the thermocouple, thereby achieving a temperature difference between the cold end and the hot end. By precisely controlling the current direction, TEC can flexibly achieve the dual functions of refrigeration and heating, thereby effectively regulating the temperature of lithium batteries and meeting the thermal management requirements under different working conditions. Compared with traditional air cooling systems, TEC has a significantly improved heat dissipation efficiency, and due to its solid-state structure, there is no risk of liquid leakage, making it more suitable for complex operating environments.

[0044] TEC is driven by applying a continuous voltage and dynamically adjusts this voltage with a temperature control algorithm to ensure that the temperature of the lithium battery is maintained within a safe range. Although this solution can effectively meet the temperature control requirements under standard environmental conditions (such as an environment close to room temperature, general sunny weather) or when the battery output power is low, considering the upper limit of the refrigeration density of TEC, in the face of extreme working conditions (such as severe cold in snow, high temperature in heat, or battery thermal runaway, etc.), it may not be able to fully meet the temperature control requirements. Another important characteristic of TEC is its transient supercooling effect. When a pulsed current is applied to TEC, the cold end will experience a significant temperature drop in a short period of time, and this phenomenon is called the transient supercooling effect. This characteristic can meet the demand for short-term high-intensity cooling in specific application scenarios, especially suitable for rapid heat dissipation and thermal management control of batteries in high-temperature environments. By applying a pulsed voltage signal several times higher than the reference voltage, the transient supercooling effect can be triggered, and the pulse amplitude and duration can be optimized under different reference voltage conditions. In addition, when the pulsed voltage changes in a periodic form, the cold end temperature will also show periodic fluctuations, and the longer the pulse period, the more significant the effect of the transient supercooling effect. This characteristic makes TEC show unique advantages in rapid temperature response and dynamic thermal management applications, especially in scenarios with thermal runaway suppression and short-term large temperature difference requirements, providing advanced and efficient thermal management support for vehicle-mounted lithium batteries.

[0045] In a specific embodiment, the battery thermal management system monitors the battery temperature and the ambient temperature and executes a pulsed refrigeration mode, a continuous refrigeration mode, an idle mode, a continuous heating mode, or a pulsed heating mode;

[0046] When the battery temperature rises abnormally or shows a trend of local thermal runaway (determined according to the overall or local thermal runaway temperature rise rate threshold and the battery temperature), the system executes the pulsed refrigeration mode;

[0047] When the battery temperature is higher than the battery temperature threshold, or the ambient temperature is greater than or equal to the first ambient temperature threshold, that is, when the battery generates a high amount of heat or the ambient temperature is higher than 35°C, the system executes the continuous refrigeration mode;

[0048] When the battery temperature is lower than the battery temperature threshold, and the ambient temperature is less than the first ambient temperature threshold and greater than or equal to the second ambient temperature threshold, that is, in a normal ambient temperature and when the battery generates a low amount of heat, the system executes the idle mode;

[0049] When the battery temperature is lower than the battery temperature threshold, and the ambient temperature is less than the second ambient temperature threshold and greater than or equal to the third ambient temperature threshold, that is, when the ambient temperature is slightly low and the battery does not generate a high amount of heat, the system executes the continuous heating mode;

[0050] When the battery temperature is lower than the battery temperature threshold, and the ambient temperature is less than the third ambient temperature threshold, that is, when the ambient temperature is extremely low (such as in snowy weather) and the battery does not generate a high amount of heat, the system executes the pulse heating mode.

[0051] The recommended values and descriptions of each temperature threshold are shown in Table 1, and the triggering conditions of each mode determined according to Table 1 are shown in Table 2.

[0052] Table 1 Threshold Type, Recommended Value and Description

[0053]

[0054]

[0055] Table 2 Triggering Conditions of Each Mode

[0056]

[0057] Specifically, the system of the present invention integrates a thermoelectric cooler and an air cooling system. By installing the thermoelectric cooler on both sides of the battery module and equipping it with a heat sink, and at the same time collaborating with the air cooling system with air as the cooling medium, efficient thermal management is achieved. The core of the present invention lies in that its integrated power electronic components together constitute a flexible operation platform. Through the temperature control strategy system, it can intelligently determine the power switch signal and the forward and reverse signal input to the PWM voltage regulator, so that it can systematically select and operate multiple working modes. This diverse working mode enables the thermoelectric cooler to be precisely controlled according to multiple signals.

[0058] The dynamic adjustment mechanism of the temperature control strategy includes: the digital controller collects the battery temperature Tbatt and the ambient temperature Tenv in real time, and matches the optimal pulse parameters through look-up tables or machine learning algorithms; when a sudden local temperature rise is detected (such as ΔT / Δt≥5℃ / s), a high-voltage pulse (k = 5) is immediately triggered, and the duration is Δt = 3s, and then it switches to the continuous mode to maintain temperature stability; the pulse frequency is adjusted according to the battery thermal inertia, and high-thermal-inertia batteries use low-frequency long pulses (such as 1Hz), and low-thermal-inertia batteries use high-frequency short pulses (such as 5Hz).

[0059] In specific applications, the system demonstrates extremely high flexibility and practicality. When signs of overheating or thermal runaway occur in the battery, the system can quickly activate the pulse cooling mode by sending a high-voltage pulse for several seconds every fixed period (such as every 15 seconds) and combining a specific forward and reverse configuration, effectively preventing the occurrence of thermal runaway. On the other hand, when the battery or ambient temperature is high, the PID controller adjusts the voltage of the thermoelectric cooler and the fan power. Using the precise duty cycle control of the PWM signal, the system can effectively maintain the battery temperature below 35℃, and the high frequency of the PWM signal reaches 980Hz. From the operation perspective of the thermoelectric cooler (TEC), this control method achieves an almost continuous cooling effect. When the temperature is normal and the battery generates little heat, the system will automatically enter the idle mode, stop the operation of the thermoelectric cooler, and only start the fan to save energy; when the ambient temperature is low and the battery is slightly hot, the system will drive the thermoelectric cooler with reverse current and stabilize the temperature at 25℃ through PID control and a 980Hz PWM signal to achieve continuous heating; in extremely cold conditions, the system will quickly increase the battery temperature through the above-mentioned high voltage, pulse signal and reverse forward and reverse settings.

[0060] In addition, the system can also output corresponding voltage trends according to different working modes (such as Figure 2 shown, where A, B, C, D, and E in the figure correspond to the voltage trends of the pulse cooling mode, continuous cooling mode, idle mode, continuous heating mode, or pulse heating mode respectively. Among them, B and D are shown as the average voltage of the PWM signal). The digital controller precisely regulates the forward and reverse PWM voltage regulator to ensure the stable operation of the system. In terms of temperature control and performance, the combination of the thermoelectric cooler and the air-cooling system, as well as the flexible switching of multiple modes, enables the system to precisely resist capacity decay at low temperatures of -15℃ and the risk of thermal runaway at high temperatures of ≥40℃. At the same time, the combination of pulse and continuous modes not only reduces energy consumption but also achieves a balance between heat dissipation and energy consumption. In addition, the pulse cooling mode can quickly respond to local high temperatures, ensure battery safety, and reduce potential losses.

[0061] In a specific embodiment, when the pulse refrigeration mode is executed, the digital controller 3 controls the adjustable voltage power supply 1 to output a high voltage through the voltage regulation signal 8, sets the forward and reverse signal 7 to 1, and controls the forward and reverse PWM voltage regulator 2 to issue a high-voltage pulse with a set continuous duration at a fixed time interval (such as every 15 seconds) through the power switch signal 6; the semiconductor thermoelectric cooler 4 enters a rapid refrigeration state under the drive of the high-voltage pulse, realizing transient rapid refrigeration of the lithium battery pack 5 and suppressing the risk of thermal runaway propagation. In the pulse refrigeration mode, the voltage input to the TEC is in the form of a pulse, and the voltage reaches a relatively high value in a short time and then rapidly drops, specifically as shown in Figure 2 shown in A

[0062] In a specific embodiment, when the continuous refrigeration mode is executed, the digital controller 3 controls the adjustable voltage power supply 1 to output the rated voltage through the voltage regulation signal 8, sets the forward and reverse signal 7 to 1, and controls the duty cycle of the forward and reverse PWM voltage regulator 2 through the power switch signal 6, thereby controlling the refrigeration power of the semiconductor thermoelectric cooler 4; the digital controller 3 also controls the air-cooling system to work in cooperation with the semiconductor thermoelectric cooler 4 through the fan power signal to dissipate heat from the lithium battery pack 5 and maintain the battery temperature at about 35°C. In the continuous refrigeration mode, the voltage input to the TEC is in the high-frequency PWM refrigeration mode, specifically as shown in Figure 2 shown in B

[0063] In a specific embodiment, when the idle mode is executed, the digital controller 3 stops sending control signals to the adjustable voltage power supply 1 and the forward and reverse PWM voltage regulator 2, and only controls the air-cooling system to dissipate heat from the lithium battery pack 5 through the fan power signal, thereby ensuring the minimum system energy consumption. In the idle mode, the voltage is maintained at a relatively low constant value, specifically as shown in Figure 2 shown in C

[0064] In a specific embodiment, when the continuous heating mode is executed, the digital controller 3 controls the adjustable voltage power supply 1 to output the rated voltage through the voltage regulation signal 8, sets the forward and reverse signal 7 to 0, and controls the duty cycle of the forward and reverse PWM voltage regulator 2 through the power switch signal 6, thereby controlling the heating power of the semiconductor thermoelectric cooler 4 to heat the lithium battery pack 5. In the continuous heating mode, the voltage input to the TEC is in the high-frequency PWM heating mode, but the voltage direction is opposite to that of the refrigeration mode, specifically as shown in Figure 2 shown in D

[0065] In a specific embodiment, when the pulse heating mode is executed, the digital controller 3 controls the adjustable voltage power supply 1 to output a high voltage through the voltage regulation signal 8, sets the forward and reverse signal 7 to 0, and controls the forward and reverse PWM voltage regulator 2 to emit high-voltage pulses with a set continuous duration at fixed time intervals through the power switch signal 6; the semiconductor thermoelectric cooler 4 enters the rapid heating state under the drive of the high-voltage pulses, realizing rapid temperature increase of the lithium battery pack 5. In the pulse heating mode, the voltage input to the TEC is in the form of pulses, and the current direction is opposite to that in the refrigeration mode, specifically as shown in Figure 2 E in

[0066] In a specific embodiment, the parameters of the high-voltage pulses are determined by the following method:

[0067] First, according to the mass m, specific heat capacity c, and target temperature drop ΔT of the lithium battery pack 5, calculate the heat to be transferred. The formula is ΔQ = m·c·ΔT;

[0068] Then, according to the instantaneous refrigeration power PTEC of the semiconductor thermoelectric cooler 4 and the heat dissipation power Pair of the air cooling system, determine the pulse duration. The formula is: Δt = ΔQ / (PTEC + Pair);

[0069] Finally, based on the rated voltage Vbase of the semiconductor thermoelectric cooler 4 and the transient supercooling requirement k, set the pulse voltage. The formula is: Vpulse = k·Vbase, 2 ≤ k ≤ 5.

[0070] The optimal k value is calibrated through experiments; after determining the pulse voltage, set this voltage as the output voltage of the adjustable voltage power supply, and dynamically adjust the output voltage to Vpulse through the voltage regulation signal sent by the digital controller. The forward and reverse PWM voltage regulator receives high or low digital signals from the digital controller, dynamically adjusts the current direction and voltage amplitude of the TEC, and generates the required pulse signal. The digital controller adjusts the duty cycle and frequency of the pulse signal in real time according to the temperature measurement signal to ensure the efficient operation of the TEC in the pulse mode.

[0071] In a specific embodiment, the designed operating temperature range is 25°C to 35°C.

[0072] In this specification, the various embodiments are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and reference can be made to the description in the method part for the relevant parts.

[0073] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A battery thermal management system based on a PWM voltage-regulated thermoelectric cooler, characterized in that, Comprising: A thermoelectric cooler system and an air-cooling system; The air-cooling system uses air as a refrigerant to provide cooling capacity for the lithium battery pack; The thermoelectric cooler system includes: a lithium battery pack, an adjustable voltage power supply, a forward and reverse PWM voltage regulator, a semiconductor thermoelectric cooler that are electrically connected in sequence, and a digital controller that is respectively connected to the adjustable voltage power supply, the forward and reverse PWM voltage regulator, and the temperature sensor on the lithium battery pack for signal connection; The adjustable voltage power supply is powered by the input of the lithium battery pack and adjusts the output voltage according to the voltage regulation signal of the digital controller to provide driving electrical energy to the forward and reverse PWM voltage regulator; The forward and reverse PWM voltage regulator outputs a high-voltage pulse or a PWM driving voltage to the semiconductor thermoelectric cooler according to the input voltage of the adjustable voltage power supply, as well as the power switch signal and the forward and reverse signal of the digital controller; The semiconductor thermoelectric cooler is arranged on both sides of the lithium battery pack and cools or heats according to the high-voltage pulse or the PWM driving voltage, so that the lithium battery pack is within the designed operating temperature range; The digital controller issues the voltage regulation signal, the power switch signal, and the forward and reverse signal according to the temperature measurement signal of the temperature sensor and the ambient temperature.

2. The battery thermal management system based on a PWM voltage-regulating thermoelectric cooler according to claim 1, characterized in that The battery thermal management system monitors the battery temperature and the ambient temperature and executes a pulse cooling mode, a continuous cooling mode, an idle mode, a continuous heating mode, or a pulse heating mode; When the battery temperature rises abnormally or there is a tendency of local thermal runaway, the system executes the pulse cooling mode; When the battery temperature is higher than the battery temperature threshold, or the ambient temperature is greater than or equal to the first ambient temperature threshold, the system executes the continuous cooling mode; When the battery temperature is lower than the battery temperature threshold, and the ambient temperature is less than the first ambient temperature threshold and greater than or equal to the second ambient temperature threshold, the system executes the idle mode; When the battery temperature is lower than the battery temperature threshold, and the ambient temperature is less than the second ambient temperature threshold and greater than or equal to the third ambient temperature threshold, the system executes the continuous heating mode; When the battery temperature is lower than the battery temperature threshold, and the ambient temperature is less than the third ambient temperature threshold, the system executes the pulse heating mode.

3. The battery thermal management system based on a PWM voltage-regulated thermoelectric cooler according to claim 2, wherein When executing the pulse cooling mode, the digital controller controls the adjustable voltage power supply to output a high voltage through the voltage regulation signal, sets the forward and reverse signal to 1, and controls the forward and reverse PWM voltage regulator to issue a high-voltage pulse with a set continuous duration at a fixed time interval through the power switch signal; the semiconductor thermoelectric cooler enters a rapid cooling state under the drive of the high-voltage pulse to achieve transient rapid cooling of the lithium battery pack.

4. The battery thermal management system based on a PWM voltage-regulating thermoelectric cooler according to claim 2, wherein When executing the continuous cooling mode, the digital controller controls the adjustable voltage power supply to output a rated voltage through the voltage regulation signal, sets the forward and reverse signal to 1, and controls the duty cycle of the forward and reverse PWM voltage regulator through the power switch signal, thereby controlling the cooling power of the semiconductor thermoelectric cooler; the digital controller also controls the air-cooling system and the semiconductor thermoelectric cooler to work together to dissipate heat from the lithium battery pack through the fan power signal.

5. The battery thermal management system based on a PWM voltage-regulated thermoelectric cooler according to claim 2, wherein When executing the idle mode, the digital controller stops sending control signals to the adjustable voltage power supply and the forward-reverse PWM voltage regulator, and controls the air-cooling system to dissipate heat from the lithium battery pack only through the fan power signal.

6. The battery thermal management system based on a PWM voltage-regulating thermoelectric cooler according to claim 2, wherein, When executing the continuous heating mode, the digital controller controls the adjustable voltage power supply to output the rated voltage through the voltage regulation signal, sets the forward-reverse signal to 0, and controls the duty cycle of the forward-reverse PWM voltage regulator through the power switch signal, so as to control the heating power of the semiconductor thermoelectric cooler and heat the lithium battery pack.

7. The battery thermal management system based on a PWM voltage-regulating thermoelectric cooler according to claim 2, characterized in that, When executing the pulse heating mode, the digital controller controls the adjustable voltage power supply to output a high voltage through the voltage regulation signal, sets the forward-reverse signal to 0, and controls the forward-reverse PWM voltage regulator to emit high-voltage pulses with a set continuous duration at a fixed time interval through the power switch signal; under the drive of the high-voltage pulses, the semiconductor thermoelectric cooler enters a rapid heating state to achieve rapid temperature increase of the lithium battery pack.

8. The battery thermal management system based on a PWM voltage-regulating thermoelectric cooler according to claim 1, wherein The parameters of the high-voltage pulses are determined by the following method: First, according to the mass m, specific heat capacity c, and target temperature drop ΔT of the lithium battery pack, calculate the heat to be transferred, and the formula is ΔQ = m·c·ΔT; Then, according to the instantaneous refrigeration power PTEC of the semiconductor thermoelectric cooler and the heat dissipation power Pair of the air-cooling system, determine the pulse duration, and the formula is: Δt = ΔQ / (PTEC + Pair); Finally, based on the rated voltage Vbase of the semiconductor thermoelectric cooler and the transient supercooling requirement k, set the pulse voltage, and the formula is: Vpulse = k·Vbase, 2 ≤ k ≤ 5.

9. The battery thermal management system based on a PWM voltage-regulated thermoelectric cooler according to claim 1, wherein The designed operating temperature range is from 25°C to 35°C.

Images