A charging pile heat management method and device and a charging pile

Abstract

The application discloses a charging pile heat management method, device and charging pile, the charging pile heat management method comprises an LLC resonant converter for the charging pile, in the inductive working area range of the working frequency of the LLC resonant converter being higher than the resonant frequency, the working frequency of the LLC resonant converter is optimized to find the working frequency point of the lowest conduction loss and switching loss of the LLC resonant converter in combination with the conduction loss and switching loss characteristics of the LLC resonant converter, the LLC resonant converter is controlled to operate at the working frequency to realize active heat control of the charging pile. The application aims to reduce the equipment operation loss, find the working frequency point of the lowest conduction loss and switching loss while meeting the requirement of the output voltage waveform quality, guarantee high-quality and high-efficiency output, and reduce the equipment operation loss.

Description

Technical Field

[0001] This invention belongs to the field of charging piles, and specifically relates to a thermal management method, device and charging pile for charging piles. Background Technology

[0002] The rapid development of new energy vehicles has placed demands on charging piles for high power density, high power, and high efficiency. DC charging piles are characterized by sufficiently high power, a wide output voltage and current range, and short-time fast charging. Existing high-power fast charging piles typically consist of a PFC (Power Factor Correction) rectifier section, represented by Vienna rectifiers, and a DC-DC section, represented by LLC resonant converters. The current demand for fast charging and high power density results in significant losses within the power module during actual operation, with the LLC resonant converter accounting for the largest proportion of these losses. The rapid increase in losses under high-power, short-time fast charging requirements leads to heat accumulation throughout the charging pile, and the limited space within the pile further complicates heat dissipation. To ensure reliable charging and long-term normal operation of the equipment, thermal management of high-power fast charging piles is urgently needed.

[0003] LLC resonant converters, due to their excellent soft-switching characteristics, significantly increase the switching frequency, thereby improving the power density of the device and enabling zero-voltage switching (ZVS) of primary-side power devices over a wide load output range. However, the wide switching frequency range makes the design and optimization of the converter's magnetic components difficult, resulting in significant conduction and turn-off losses, which reduces the high efficiency of the resonant converter. In existing technologies using variable-frequency PFM control, the resonant tank circuit experiences high current and severe losses under light load and no-load conditions. When operating over a wide gain range, LLC resonant converters operating near the resonant frequency typically employ an open-loop fixed-frequency mode, which offers lower control complexity and cost, but increases the voltage stress on the rectifier diodes, leading to reduced efficiency and increased device size and weight. Using a hybrid control method of PFM or PWM to drive the switching transistors can improve no-load efficiency, but the output voltage quality during the transient switching of the hybrid control is not guaranteed. Therefore, how to combine the control of LLC resonant converters for charging pile thermal management has become a critical technical problem that urgently needs to be solved. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a thermal management method, device and charging pile for charging piles, which addresses the above-mentioned problems of the prior art. The present invention aims to reduce the operating loss of equipment, and while meeting the requirements of output voltage waveform quality, find the operating frequency point that minimizes conduction loss and switching loss, so as to ensure high-quality and high-efficiency output while reducing the operating loss of equipment.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A thermal management method for charging piles includes an LLC resonant converter for the charging pile. Within the inductive operating range where the operating frequency of the LLC resonant converter is higher than the resonant frequency, the operating frequency of the LLC resonant converter is optimized by combining the conduction loss and switching loss characteristics of the LLC resonant converter to find the operating frequency that minimizes the conduction loss and switching loss of the LLC resonant converter. The LLC resonant converter is then controlled to operate at this operating frequency to reduce losses, thereby achieving active thermal control of the charging pile.

[0007] Optionally, the optimization of the operating frequency of the LLC resonant converter by combining the conduction loss and switching loss characteristics of the LLC resonant converter to find the operating frequency that minimizes the conduction loss and switching loss of the LLC resonant converter includes:

[0008] S101, Determine the output voltage u at time k+1. o The maximum value of the operating frequency f at time k+1 is determined by combining the upper limit λ of the output voltage ripple with the gain-frequency curve of the LLC resonant converter. max and minimum value f min ;

[0009] S102, for the maximum value f of the operating frequency at time k+1. max and minimum value f min Given a defined operating frequency range f, divide the operating frequency range f into N equal parts at specified intervals, and initialize the value of the iteration variable i.

[0010] S103, for any i-th operating frequency f at time k+1 i (k+1), calculate the i-th stage loss of the LLC resonant converter at time k+1, and the output voltage u at time k+1. o The output voltage u of the i-th level at time k+1 is obtained by combining the gain calculation formula. o，i (k+1), and combined with the output voltage u at time k+1 i Calculate the voltage ripple Δu at time k+1. o，i (k+1);

[0011] S104, if the voltage ripple Δu at time k+1 is... o，i If (k+1) is less than or equal to the preset threshold λ, then proceed to step S105; otherwise, proceed to step S106.

[0012] S105, Substitute the i-th stage loss of the LLC resonant converter at time k+1 into the preset penalty function to calculate the penalty function value;

[0013] S106, increment the iteration variable i by 1. If the iteration variable i after incrementing by 1 is less than or equal to N, then jump to step S103; if the iteration variable i after incrementing by 1 is greater than N, then jump to step S107.

[0014] S107, among all penalty function values, select the i-th level operating frequency f corresponding to the smallest penalty function value. i (k+1) is the operating frequency found that minimizes the conduction and switching losses of the LLC resonant converter.

[0015] Optionally, the functional expression for calculating the i-th stage loss of the LLC resonant converter at time k+1 in step S103 is:

[0016]

[0017]

[0018] In the above formula, P con R is the conduction loss at time k+1. on U is the on-resistance of the power device. out Let R be the output voltage at time k+1, n be the turns ratio of the primary and secondary windings of the transformer, and R be the voltage at time k+1. o For the output resistance, T s For the switching cycle, L m For the magnetizing inductor, P sw P is the switching loss at time k+1. off Let t be the turn-off loss at time k+1. f I is the duration of the overlap between the turn-off current and voltage of the switching transistor. roff C represents the instantaneous current value at the moment of shutdown. oss This is the output capacitor for the power device.

[0019] Optionally, in step S103, the output voltage u at time k+1 is... o The output voltage u of the i-th level at time k+1 is obtained by combining the gain calculation formula. o，i (k+1) includes:

[0020] S201, the operating frequency f of the i-th gear at time k+1. i After normalization (k+1), input the preset gain calculation formula G(ω) s The DC output gain of the i-th stage converter at time k+1 is obtained.

[0021] S202, the output voltage u at time k+1 i As the input voltage U in According to U out =U in G(ω s The output voltage U is obtained.out The i-th output voltage u at time k+1 o，i (k+1).

[0022] Optionally, the preset gain calculation formula G(ω) in step S201 s The function expression for ) is:

[0023]

[0024] In the above formula, G(ω) s ω represents the DC output gain of the converter. s Where is the operating angular frequency, k is the normalized inductance, and f is the operating frequency. n Let Q be the normalized operating switching frequency, and Q be the quality factor, and we have:

[0025]

[0026] In the above formula, L r For resonant inductance, L m For the magnetizing inductance, C r For resonant capacitance, R eq Let f be the resistance of the load and rectifier circuit equivalent to the primary side of the transformer, and f be the operating frequency. r It is the resonant frequency.

[0027] Optionally, in step S103, the output voltage u at time k+1 is considered. o Calculate the voltage ripple Δu at time k+1. o，i The function expression for (k+1) is:

[0028] Δu i，i (k+1)=u i，i (k+1)-u o ,

[0029] In the above formula, u o，i (k+1) represents the i-th output voltage at time k+1.

[0030] Optionally, the function expression of the preset penalty function in step S105 is:

[0031] h t，i =k1P con，i (k+1)+k2P sw，i (k+1),

[0032] In the above formula, h t，i Let P be the penalty function value for the i-th level, k1 and k2 be the penalty coefficients, and P be the value of the penalty function for the i-th level. con，i (k+1) represents the i-th stage conduction loss of the LLC resonant converter at time k+1, P sw，iLet be the switching loss of the i-th stage of the LLC resonant converter at time k+1.

[0033] In addition, the present invention also provides a charging pile thermal management system, including a microprocessor and a memory interconnected thereto, wherein the microprocessor is programmed or configured to execute the charging pile thermal management method.

[0034] In addition, the present invention provides a computer-readable storage medium storing a computer program that is programmed or configured by a microprocessor to execute the charging pile thermal management method.

[0035] Furthermore, the present invention also provides a charging pile, wherein the charging pile is provided with an LLC resonant converter and a control unit for controlling the LLC resonant converter, the control unit including a microprocessor and a memory interconnected thereto, the microprocessor being programmed or configured to execute the charging pile thermal management method, and the charging pile is further provided with a phase change material heat sink for dissipating heat from the charging pile, the phase change material heat sink comprising being filled with a phase change material for absorbing heat from the charging pile by melting from a solid to a liquid state.

[0036] Compared with the prior art, the present invention has the following main advantages:

[0037] 1. The method of the present invention performs frequency conversion loss reduction control on the main heat-generating part of the high-power fast charging pile, namely the LLC resonant converter, thereby performing active thermal control on the high-power fast charging pile.

[0038] 2. The method of this invention includes an LLC resonant converter for charging piles. Within the inductive operating region where the operating frequency of the LLC resonant converter is higher than the resonant frequency, the operating frequency of the LLC resonant converter is optimized by combining the characteristics of its conduction and switching losses to find the operating frequency that minimizes the conduction and switching losses. The LLC resonant converter is controlled to operate at this operating frequency to reduce losses, thereby achieving active thermal control of the charging pile. This reduces equipment operating losses and, while meeting the requirements for output voltage waveform quality, finds the operating frequency point that minimizes conduction and switching losses, ensuring high-quality and high-efficiency output while reducing equipment operating losses. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the basic process of the method in an embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram of the LLC resonant converter in an embodiment of the present invention.

[0041] Figure 3 This is the DC gain-frequency characteristic of the LLC resonant converter in this embodiment of the invention.

[0042] Figure 4 This is a flowchart of variable frequency loss reduction control based on model prediction in an embodiment of the present invention.

[0043] Figure 5 This is a schematic diagram illustrating the combined principle of two methods for thermal management of charging piles in an embodiment of the present invention.

[0044] Figure 6 This is a schematic diagram of the phase transition transient model in an embodiment of the present invention.

[0045] Figure 7 This is a schematic diagram of the heat transfer process of the heat dissipation model in an embodiment of the present invention.

[0046] Figure 8 This is a schematic diagram of the cross-sectional structure of the phase change heat sink in an embodiment of the present invention.

[0047] Figure 9 The above is a waveform diagram of the thermal management method in an embodiment of the present invention. Detailed Implementation

[0048] like Figure 1 As shown, this embodiment provides a thermal management method for charging piles, including an LLC resonant converter for the charging pile. Within the inductive operating range where the LLC resonant converter's operating frequency is higher than its resonant frequency, the operating frequency of the LLC resonant converter is optimized based on its conduction and switching loss characteristics to find the frequency that minimizes both conduction and switching losses. The LLC resonant converter is then controlled to operate at this frequency with frequency conversion and loss reduction to achieve active thermal control of the charging pile. This embodiment achieves active thermal control of the high-power fast charging pile by implementing frequency conversion and loss reduction control on the main heat-generating component, the LLC resonant converter. This ensures high-quality, high-efficiency output while reducing equipment operating losses, stabilizing the transient process of equipment heating, enhancing the equipment's heat dissipation effect, improving short-term overload capacity, thereby reducing costs and improving equipment reliability.

[0049] like Figure 2 As shown, the LLC resonant converter in this embodiment is specifically a full-bridge LLC resonant converter, including a square wave generator, a resonant cavity, and a transformer and rectifier unit connected in sequence. The square wave generator is used to convert the DC power supply U... DC The output voltage generates a square wave through switching transistors Q1 to Q4, and the resonant cavity is connected to capacitor C. r and inductor L r It is connected in series, where L m The resonant inductance of the primary side of the transformer, and the output voltage u of the transformer in the rectifier unit through the secondary side of the transformer are connected to the full-bridge rectifier circuit. oFurthermore, an output capacitor is connected in parallel at the output terminal of the full-bridge rectifier circuit. Since the LLC resonant converter is the main heat-generating component of a high-power fast-charging station, one problem to be solved in this embodiment is to implement frequency conversion loss reduction control, thereby achieving active thermal control of the high-power fast-charging station. For example... Figure 3 As shown, based on the DC gain-frequency characteristics of the LLC resonant converter, when the operating frequency is below the resonant frequency, the DC gain is small and its variation is not monotonic, belonging to the capacitive operating region. In this region, the operating frequency is low and ZVS (zero-voltage turn-on) cannot be achieved, easily leading to increased losses and increasing the design difficulty of the filter circuit; therefore, it is not considered. When the operating frequency is above the resonant frequency, it belongs to the inductive operating region, where the DC output voltage gain shows a negative correlation with the operating frequency. Within the inductive operating region, combining the characteristics of conduction and switching losses, the converter's operating frequency is optimized based on a model prediction algorithm. This finds the operating frequency point that minimizes conduction and switching losses while ensuring the output voltage waveform quality meets requirements, achieving high-quality, high-efficiency output.

[0050] In this embodiment, the operating frequency of the LLC resonant converter is optimized by combining its conduction and switching loss characteristics. The operating frequency that minimizes the conduction and switching losses of the LLC resonant converter is then used to implement model-predictive frequency conversion loss reduction control. Figure 4 As shown, in this embodiment, the operating frequency of the LLC resonant converter is optimized by combining the conduction loss and switching loss characteristics of the LLC resonant converter to find the operating frequency that minimizes the conduction loss and switching loss of the LLC resonant converter. This includes:

[0051] S101, Determine the output voltage u at time k+1. o The maximum value of the operating frequency f at time k+1 is determined by combining the upper limit λ of the output voltage ripple with the gain-frequency curve of the LLC resonant converter. max and minimum value f min ;

[0052] S102, for the maximum value f of the operating frequency at time k+1. max and minimum value f min A defined operating frequency range f is divided into N equal parts at specified intervals, resulting in N operating frequencies, which can be expressed as:

[0053]

[0054] In the above formula, Δf is the specified interval; the value of the iteration variable i is initialized;

[0055] S103, for any i-th operating frequency f at time k+1 i(k+1), calculate the i-th stage loss of the LLC resonant converter at time k+1, and the output voltage u at time k+1. o The output voltage u of the i-th level at time k+1 is obtained by combining the gain calculation formula. o，i (k+1), and combined with the output voltage u at time k+1 o Calculate the voltage ripple Δu at time k+1. o，i (k+1);

[0056] S104, if the voltage ripple Δu at time k+1 is... o，i If (k+1) is less than or equal to the preset threshold λ, then proceed to step S105; otherwise, proceed to step S106.

[0057] S105, Substitute the i-th stage loss of the LLC resonant converter at time k+1 into the preset penalty function to calculate the penalty function value;

[0058] S106, increment the iteration variable i by 1. If the iteration variable i after incrementing by 1 is less than or equal to N, then jump to step S103; if the iteration variable i after incrementing by 1 is greater than N, then jump to step S107.

[0059] S107, among all penalty function values, select the i-th level operating frequency f corresponding to the smallest penalty function value. i (k+1) is the operating frequency found that minimizes the conduction and switching losses of the LLC resonant converter.

[0060] This embodiment achieves the optimization design of the operating frequency of the LLC resonant converter through the above method. While ensuring that the output voltage waveform quality meets the requirements, it finds the operating frequency point that minimizes the conduction loss and switching loss, thereby achieving high-quality and high-efficiency output.

[0061] In step S103 of this embodiment, the functional expression for calculating the i-th stage loss of the LLC resonant converter at time k+1 is:

[0062]

[0063]

[0064] In the above formula, P con R is the conduction loss at time k+1. on U is the on-resistance of the power device. out Let R be the output voltage at time k+1, n be the turns ratio of the primary and secondary windings of the transformer, and R be the voltage at time k+1. o For the output resistance, T s For the switching cycle, L m For the magnetizing inductor, P sw P is the switching loss at time k+1.off Let t be the turn-off loss at time k+1. f I is the duration of the overlap between the turn-off current and voltage of the switching transistor. roff C represents the instantaneous current value at the moment of shutdown. oss This is the output capacitor for the power device. Since the LLC resonant converter can achieve ZVS conduction, the turn-on loss is negligible.

[0065] In step S103 of this embodiment, the output voltage u at time k+1 is... o The output voltage u of the i-th level at time k+1 is obtained by combining the gain calculation formula. o，i (k+1) includes:

[0066] S201, the operating frequency f of the i-th gear at time k+1. i After normalization (k+1), input the preset gain calculation formula G(ω) s The DC output gain of the i-th stage converter at time k+1 is obtained.

[0067] S202, the output voltage u at time k+1 o As the input voltage U in According to U out =U in G(ω s The output voltage U is obtained. out The i-th output voltage u at time k+1 o，i (k+1).

[0068] In step S201 of this embodiment, the preset gain calculation formula G(ω) s The function expression for ) is:

[0069]

[0070] In the above formula, G(ω) s ω represents the DC output gain of the converter. s Where is the operating angular frequency, k is the normalized inductance, and f is the operating frequency. n Let Q be the normalized operating switching frequency, and Q be the quality factor, and we have:

[0071]

[0072] In the above formula, L r For resonant inductance, L m For the magnetizing inductance, C r For resonant capacitance, R eq Let f be the resistance of the load and rectifier circuit equivalent to the primary side of the transformer, and f be the operating frequency. r It is the resonant frequency.

[0073] In step S103 of this embodiment, the output voltage u at time k+1 is considered. o Calculate the voltage ripple Δu at time k+1. o，i The function expression for (k+1) is:

[0074] Δu o，i (k+1)=u o，i (k+1)-u o ,

[0075] In the above formula, u i，i (k+1) represents the i-th output voltage at time k+1.

[0076] The function expression of the preset penalty function in step S105 of this embodiment is:

[0077] h t，i =k1P con，i (k+1)+k2P sw，i (k+1),

[0078] In the above formula, h t，i Let P be the penalty function value for the i-th level, k1 and k2 be the penalty coefficients, and P be the value of the penalty function for the i-th level. con，i (k+1) represents the i-th stage conduction loss of the LLC resonant converter at time k+1, P sw，i Let be the switching loss of the i-th stage of the LLC resonant converter at time k+1.

[0079] like Figure 6 As shown, this embodiment achieves thermal management of charging piles by first reducing operating losses and minimizing heat generation at the source. To address this issue, a model-based frequency conversion loss reduction control method is employed. Secondly, to meet the application requirements of high-power fast charging, the heat dissipation effect of the equipment is enhanced, and the short-term overload capacity is improved, thereby reducing costs and increasing the reliability of equipment operation. Specifically, a heat dissipation enhancement thermal management method based on phase change materials is used. This method utilizes phase change materials to increase the heat capacity of the heat sink, thereby stabilizing the transient process of equipment heating. When the charging pile is engaged in fast charging and the equipment temperature rises, the latent heat absorption characteristic of the phase change material is used to manage the thermal performance of the equipment.

[0080] like Figure 6As shown, the transient change process of a phase change material (PCM) is as follows: Before entering the phase change region, the volume ratio of the solid phase material is θ1 = 1, and the volume ratio of the liquid phase material is θ2 = 0. After entering the phase change region, the proportion of solid material begins to decrease, while the proportion of liquid material begins to increase. When the temperature reaches the melting point, all materials melt into a liquid state, at which point the volume ratio of solid material is θ1 = 0, and the volume ratio of liquid material is θ2 = 1. Throughout the transient process, the total volume of the material remains constant, i.e., θ1 + θ2 = 1. During the melting process, the PCM absorbs heat while its temperature remains approximately constant; this process can be approximated as having infinite heat capacity. This characteristic can be used to achieve instantaneous temperature control of equipment. The heat dissipation process of a heat sink using PCM is as follows: Figure 7 As shown in the diagram. Specifically, when the power devices inside the charging pile are working, they generate heat due to power loss. This heat is transferred to the heat sink via thermal conduction, and the heat sink then transfers the heat to the phase change material (PCM) in the grid via thermal conduction. The PCM melts after reaching its melting point. During melting, the PCM absorbs a large amount of heat and maintains the temperature of the power devices within a certain range, providing short-term protection. Furthermore, the heat sink wall and the upper surface of the PCM are in contact with the air, and the heat is carried away by the air through convection, thus achieving a cooling effect and heat dissipation. In this embodiment, considering the actual operating conditions of the charging pile and the operating temperature of the internal power devices, the melting point, latent heat of phase change, density, and thermal conductivity of the PCM are compared. LM80 metallic PCM with a melting point of 80℃ is selected as the core PCM filling material for the PCM heat sink. A cross-sectional view of the PCM heat sink is shown in the diagram. Figure 8 As shown, the phase change material heat sink has fins at the bottom and grooves arranged in an array at the top, with phase change material placed in the grooves. When the case temperature of the power device reaches 80°C, the phase change material heat sink can absorb a large amount of heat, providing short-term temperature protection to improve the operational reliability of the power device and extend its service life.

[0081] Figure 9 The image shown is a waveform comparison diagram between the charging pile thermal management method in this embodiment and the traditional method. Figure 9 It can be seen that the thermal management method of high-power fast charging piles based on frequency conversion loss reduction and phase change heat dissipation can ensure high-quality and high-efficiency output while reducing equipment operating losses, stabilizing the transient process of equipment heating, enhancing the heat dissipation effect of the equipment, improving short-term overload capacity, thereby reducing costs and improving the reliability of equipment operation.

[0082] In summary, the thermal management method for charging piles in this embodiment includes a frequency conversion loss reduction thermal management method based on model prediction algorithms and a heat dissipation enhancement thermal management method based on phase change materials. The frequency conversion loss reduction thermal management method based on model prediction algorithms can reduce equipment operating losses. While ensuring the output voltage waveform quality meets the requirements, it finds the operating frequency point that minimizes conduction and switching losses, ensuring high-quality and high-efficiency output while reducing equipment operating losses. The heat dissipation enhancement thermal management method based on phase change materials can increase the heat capacity of the heat sink by utilizing phase change materials, thereby stabilizing the transient process of equipment heating, enhancing the heat dissipation effect of the equipment, improving short-term overload capacity, and thus reducing costs and improving the reliability of equipment operation.

[0083] Furthermore, this embodiment also provides a charging pile thermal management system, including a microprocessor and a memory interconnected, wherein the microprocessor is programmed or configured to execute the charging pile thermal management method. This embodiment also provides a computer-readable storage medium storing a computer program for being programmed or configured by the microprocessor to execute the charging pile thermal management method. Additionally, this embodiment provides a charging pile, which includes an LLC resonant converter and a control unit for controlling the LLC resonant converter. The control unit includes a microprocessor and a memory interconnected, wherein the microprocessor is programmed or configured to execute the charging pile thermal management method. This embodiment also includes a phase change material (PCM) heat sink for dissipating heat from the charging pile. The PCM heat sink is filled with a PCM material that absorbs heat from the charging pile by melting from a solid state to a liquid state. The enhanced heat dissipation based on the PCM material increases the heat capacity of the heat sink, thereby stabilizing the transient process of equipment heating, enhancing the equipment's heat dissipation effect, improving short-term overload capacity, and thus reducing costs and improving the reliability of equipment operation.

[0084] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-readable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create an implementation for the process. Figure 1 One or more processes and / or boxes Figure 1 The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0085] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A thermal management method for charging piles, characterized in that, This includes an LLC resonant converter for charging piles. Within the inductive operating region where the LLC resonant converter's operating frequency is higher than its resonant frequency, the operating frequency is optimized by considering the converter's conduction and switching loss characteristics to find the frequency that minimizes both conduction and switching losses. The LLC resonant converter is then controlled to operate at this frequency with frequency conversion and loss reduction to achieve active thermal control of the charging pile. The optimization of the LLC resonant converter's operating frequency to minimize conduction and switching losses by considering its conduction and switching loss characteristics includes: S101, Confirm Output voltage at time and the upper limit of output voltage ripple Determining the frequency by combining the gain-frequency curve of the LLC resonant converter Maximum operating frequency at any given time and minimum value ; S102, for example, by Maximum operating frequency at any given time and minimum value Determined operating frequency range The operating frequency range is divided at specified intervals. conduct N Divide the operating frequency into N levels; initialize the value of the iteration variable i; S103, targeting Any i-th operating frequency at time i ,calculate The loss of the i-th stage of the LLC resonant converter at time i will be Output voltage at time Combined with the gain calculation formula, we obtain Output voltage of the i-th level at time i and combined Output voltage at time Calculate Voltage ripple at time i ; S104, if Voltage ripple at time i Less than or equal to the preset threshold If yes, proceed to step S105; otherwise, proceed to step S106. S105, The i-th stage loss of the LLC resonant converter at time t is substituted into the preset penalty function to calculate the penalty function value; S106, increment the iteration variable i by 1. If the iteration variable i after incrementing by 1 is less than or equal to N, then jump to step S103; if the iteration variable i after incrementing by 1 is greater than N, then jump to step S107. S107, among all penalty function values, select the i-th operating frequency corresponding to the smallest penalty function value. This was found to be the operating frequency that minimizes the conduction and switching losses of the LLC resonant converter.

2. The thermal management method for charging piles according to claim 1, characterized in that, Calculation in step S103 The functional expression for the i-th stage loss of the LLC resonant converter at time t is: ， ， In the above formula, The conduction loss at time k+1 is... This is the on-resistance of the power device. The output voltage at time k+1 This refers to the turns ratio of the primary and secondary windings of the transformer. For output resistance, For the switching cycle, For magnetizing inductance, The switching loss at time k+1 is... This represents the shutdown loss at time k+1. This refers to the duration of the overlap between the switching current and voltage during transistor turn-off. This is the instantaneous current value at the moment of shutdown. This is the output capacitor for the power device.

3. The thermal management method for charging piles according to claim 2, characterized in that, In step S103, Output voltage at time Combined with the gain calculation formula, we obtain Output voltage of the i-th level at time i include: S201, Operating frequency at time i Normalized input into the preset gain calculation formula get The DC output gain of the i-th stage converter at time i; S202, Output voltage at time As input voltage ,according to Obtain the output voltage As Output voltage of the i-th level at time i .

4. The thermal management method for charging piles according to claim 3, characterized in that, The preset gain calculation formula in step S201 The function expression is: ， In the above formula, For the DC output gain of the converter, The operating angular frequency, This is the normalized value of inductance. To normalize the operating switching frequency, Let be the quality factor, and we have: ， ， ， In the above formula, It is a resonant inductor. For magnetizing inductance, It is a resonant capacitor. This is the resistance of the load and rectifier circuit equivalent to the primary side of the transformer. For operating frequency, It is the resonant frequency.

5. The thermal management method for charging piles according to claim 1, characterized in that, In step S103, combine Output voltage at time Calculate Voltage ripple at time i The function expression is: ， In the above formula, for The output voltage of the i-th level at time i.

6. The thermal management method for charging piles according to claim 1, characterized in that, The function expression for the preset penalty function in step S105 is: ， In the above formula, Let i be the value of the penalty function for the i-th level. and The penalty coefficient is... for The conduction loss of the i-th stage of the LLC resonant converter at time step [i]. for The switching loss of the i-th stage of the LLC resonant converter at time t.

7. A thermal management system for charging piles, comprising a microprocessor and a memory interconnected, characterized in that, The microprocessor is programmed or configured to execute the thermal management method for charging piles according to any one of claims 1 to 6.

8. A computer-readable storage medium storing a computer program, characterized in that, The computer program is used to be programmed or configured by a microprocessor to execute the thermal management method for charging piles according to any one of claims 1 to 6.

9. A charging pile, wherein the charging pile includes an LLC resonant converter and a control unit for controlling the LLC resonant converter, the control unit comprising a microprocessor and a memory interconnected thereon, characterized in that, The microprocessor is programmed or configured to execute the thermal management method for the charging pile according to any one of claims 1 to 6, wherein the charging pile is further provided with a phase change material heat sink for dissipating heat from the charging pile, the phase change material heat sink comprising a phase change material filled with a phase change material for absorbing heat from the charging pile by melting from a solid to a liquid state.

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