Temperature estimation method

Abstract

A temperature estimation method disclosed by the present invention is applied to a liquid cooling heater, the liquid cooling heater comprises a water channel and a plurality of membrane elements laid on the water channel in sequence, and the temperature estimation method comprises the steps of regarding the plurality of membrane elements and sub-water channels below the plurality of membrane elements as a plurality of thermal units connected in parallel in sequence to establish a thermal impedance model of the liquid cooling heater; based on the power of the multiple membrane elements, the water channel water inlet temperature Tin and the water channel water outlet temperature Tout, the cooling water average temperature Tck (k = 1, 2, 3,..., n) of each sub-water channel is obtained; establishing an equivalent circuit model according to a Cauer model rule; and obtaining a corresponding state space expression according to the equivalent circuit model, taking the heating power Pk and the cooling water uniform temperature Tck of the membrane element as input quantities, and taking the membrane temperature Tpk of the membrane element as a state quantity and an output quantity. According to the invention, the problem that the temperature estimation of the heating element of the existing liquid cooling heater has many restrictions is solved, and the open-loop observation under the condition of lack of feedback is realized.

Description

Technical Field

[0001] The invention relates to the technical field of power electronic control, and in particular to a temperature estimation method. Background Art

[0002] Liquid-cooled heaters are usually composed of water channels and heating elements. The surface area of ​​the heating element is large, and it is difficult to measure the overall surface temperature. For example, it is not convenient to directly measure the overall temperature through local surface-mounted thermistors.

[0003] In the prior art, there are usually two ways to estimate the temperature of the heating element of a liquid-cooled heater. One is to directly measure it with a surface-mounted thermistor. However, the surface-mounted thermistor can only measure the local temperature but not the overall temperature, and additional hardware is required. When the area of ​​the heating element is large, the measurement is time-consuming and labor-intensive, and it is difficult to measure accurately. The second is to estimate the resistance in real time based on the current-voltage relationship of the heating element, and then estimate the temperature through the resistance-temperature characteristic. If the resistance value is not a univariate function of the temperature, it cannot be used.

[0004] Currently, there are many limitations in estimating the temperature of the heating elements of existing liquid-cooled heaters, and no effective solution has been proposed yet. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a temperature estimation method to at least solve the problem that there are many limitations in the temperature estimation of the heating element of the existing liquid-cooled heater.

[0006] The embodiment of the present invention provides the following technical solutions:

[0007] An embodiment of the present invention provides a temperature estimation method, characterized in that it is applied to a liquid-cooled heater, wherein the liquid-cooled heater includes a water channel and a plurality of membrane elements sequentially laid on the water channel, and the temperature estimation method includes:

[0008] The plurality of membrane elements and the sub-water channels below the plurality of membrane elements are regarded as a plurality of thermal units connected in parallel in sequence to establish a thermal impedance model of the liquid-cooled heater, wherein the thermal impedance model includes the coupled membrane inter-thermal resistance R between adjacent membrane elements. o , the membrane-water thermal resistance R between each of the membrane elements and the cooling water in the corresponding sub-channel, and the heat capacity C of each of the membrane elements;

[0009] Based on the power of the membrane elements, the water channel inlet temperature T in and water outlet temperature T out Get the average cooling water temperature T of each sub-channel ck (k=1, 2, 3, ..., n);

[0010] According to the Cauer model rule, the coupling film thermal resistance R o , the membrane water thermal resistance R is equivalent to a resistor, the heat capacity C is equivalent to a capacitor, and the cooling water average temperature difference ΔT between adjacent sub-channels ck Equivalent to a voltage source, the heating power P of each membrane element k Equivalent to a current source, the average temperature of the cooling water in each sub-channel is T ck is equivalent to the membrane node reference ground of the corresponding membrane element, the membrane temperature T of each membrane element pk Equivalent to the observed quantity, and establish an equivalent circuit model;

[0011] The corresponding state space expression is obtained according to the equivalent circuit model, and the heating power Pk of the membrane element and the average temperature T ck As input, the membrane temperature T pk As the state quantity and output quantity, the membrane temperature T of the membrane element is obtained. pk .

[0012] Furthermore, each of the membrane elements and the sub-water channel corresponding to the membrane element is a thermal unit.

[0013] Furthermore, the average temperature of the cooling water in the plurality of sub-channels is T ck Myopia is a linear change.

[0014] Furthermore, the coupling inter-film thermal resistance R between adjacent film elements o , the membrane-water thermal resistance R between each membrane element and the cooling water in the corresponding sub-channel, and the heat capacity C of each membrane element are approximately equal.

[0015] Furthermore, the power of the plurality of membrane elements, the water channel inlet temperature T in and water outlet temperature T out Get the average cooling water temperature T of each sub-channel ck include:

[0016] Based on the power P of multiple membrane elements k , water channel inlet temperature T in and water outlet temperature T out Obtain the water temperature rise value ΔT of each sub-water channel k ;

[0017] Based on the water temperature increase value ΔT k Get the average cooling water temperature T ck .

[0018] Furthermore, the water temperature increase value ΔT k The calculation formula is as follows:

[0019]

[0020] Wherein, k is used to indicate the number of the membrane elements, i=1, 2, 3, ..., n, and n is the number of the membrane elements.

[0021] Furthermore, the calculation formula of the cooling water average temperature is as follows:

[0022]

[0023] Furthermore, the state space expression is:

[0024]

[0025] Compared with the prior art, the at least one technical solution adopted in the embodiment of the present invention can achieve the following beneficial effects:

[0026] A temperature estimation method of the present invention regards multiple membrane elements and multiple sub-water channels under the membrane elements as multiple thermal units connected in parallel in sequence, and establishes a thermal impedance model of a liquid-cooled heater. After obtaining the average temperature of the cooling water in the sub-water channels, an equivalent circuit model is established for the thermal impedance model according to the Cauer model rule. Finally, the corresponding state space expression is obtained according to the equivalent circuit model. Therefore, when the water temperature at the inlet and outlet of the water channel is used as the input, the membrane temperature T of the membrane element can be obtained according to the state space expression. pk , and no external equipment is required, nor is it limited by the resistance of the membrane element, which solves the problem that there are many limitations on temperature estimation of the heating elements of existing liquid-cooled heaters. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 Schematic diagram of the principle of the Cauer model of an embodiment of the present invention;

[0029] Figure 2 is a flow chart of a temperature estimation method according to an embodiment of the present invention;

[0030] Figure 3 A simplified thermal model of a liquid-cooled heater according to an embodiment of the present invention including a plurality of membrane elements;

[0031] Figure 4 for Figure 3Thermal model parameter diagram for the mesothermal model;

[0032] Figure 5 for Figure 3 Equivalent circuit model of

[0033] Figure 6 for Figure 5 Schematic diagram of observer input and output of equivalent circuit model;

[0034] Figure 7 A simplified thermal model of a liquid-cooled heater according to an embodiment of the present invention including two membrane elements;

[0035] Figure 8 for Figure 7 Thermal model parameter diagram for the mesothermal model;

[0036] Fig. 9 for Figure 7 Equivalent circuit model of

[0037] Fig.10 for Fig. 9 Schematic diagram of the observer input and output of the equivalent circuit model. DETAILED DESCRIPTION

[0038] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0039] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0040] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0041] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0042] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the examples can be practiced without these specific details.

[0043] This specification embodiment proposes a processing solution: Figure 2 As shown in FIG. 1 , a temperature estimation method of the present invention establishes an equivalent circuit model based on the heat capacity and thermal resistance of each part of the liquid-cooled heater using the Cauer model, obtains a state space expression according to the equivalent circuit model, and then calculates the state space expression according to the water channel inlet temperature T in and water outlet temperature T out Get the average temperature of cooling water, and finally calculate the heating power P of membrane element k and the average temperature of cooling water are used as the input of the state space expression, and the membrane temperature T pk As the output of the state space expression, the membrane temperature T of the membrane element can be obtained only based on the heating power of the membrane element and the inlet and outlet temperatures of the water channel. pk , which realizes open-loop observation in the absence of feedback conditions and solves the problem that there are many limitations in temperature estimation of the heating elements of existing liquid-cooled heaters.

[0044] The technical solutions provided by various embodiments of the present application are described below in conjunction with the accompanying drawings.

[0045] Example 1

[0046] A temperature estimation method of the present invention is based on the Cauer model, which is a commonly used thermal impedance model rule. Figure 1As shown, each RC node represents a part of the actual physical model, R is the thermal resistance of the part, and C is the thermal capacitance of the part. Therefore, the advantage of this model is that it has a clear physical meaning and is applicable to various physical models with measurable thermal resistance and heat capacitance.

[0047] like Figures 2 to 6 As shown, a temperature estimation method of the present invention is applied to a liquid-cooled heater, which includes a water channel and a plurality of membrane elements sequentially laid on the water channel.

[0048] The liquid-cooled heater includes a water channel and a plurality of heating films, and the membrane element is an independently controllable part of the heating film.

[0049] The membrane element is used to consume electrical energy to increase its own temperature. After the cooling water in the water channel flows through the membrane element, it can take away the heat of the membrane element and increase its own temperature, thereby heating the cooling water in the water channel.

[0050] There may be one or more membrane elements.

[0051] For example, multiple membrane elements with independent power can share the same cooling water channel, such as Figure 3 As shown, multiple membrane elements with independently controllable power can be used as heating elements and share the same water channel.

[0052] The temperature estimation method comprises:

[0053] Step S102: Consider the multiple membrane elements and the sub-water channels under the multiple membrane elements as multiple thermal units connected in parallel in sequence to establish a thermal impedance model of the liquid-cooled heater, wherein the thermal impedance model includes the coupled membrane thermal resistance R between adjacent membrane elements. o , the membrane-water thermal resistance R between each membrane element and the cooling water in the corresponding sub-channel, and the heat capacity C of each membrane element.

[0054] Wherein, each membrane element and the sub-water channel corresponding to the membrane element constitute a thermal unit.

[0055] Among them, since the power of each membrane element is independent of each other, but the temperature is different, there is thermal resistance coupling between their contact surfaces, that is, the thermal resistance between the coupled membranes R o , and each membrane element has a heat capacity C, and there is also a membrane water thermal resistance R between the membrane element and the cooling water in the sub-channel, from which it can be concluded that Figure 3 Thermal model parameters of each part of the model, such as Figure 4 As shown, except for the thermal resistance R o In addition, the heating power P of each membrane element is also shown. k (k=1, 2, 3, ..., n), the membrane temperature value T of each membrane element pk (k=1、2、3、...、n), average cooling water temperature T under each membrane elementck (k=1、2、3、...、n), water channel inlet temperature T in and water outlet temperature T out , where k represents the number of membrane elements and n represents the number of membrane elements.

[0056] Through step S102, a thermal impedance model of the liquid-cooled heater can be preliminarily established according to various parameters of the liquid-cooled heater membrane element.

[0057] Step S104: Obtain the average cooling water temperature T of each sub-channel based on the power of multiple membrane elements, the water channel inlet temperature Tin, and the water channel outlet temperature Tout. ck (k=1, 2, 3, ..., n).

[0058] Among them, since the specific heat capacity of water is very large and the temperature difference between the cooling water temperature of the sub-channel and the membrane element is large, the average temperature of the cooling water can be approximated as a piecewise linear function of the distance flowing through the water channel. Each membrane element constitutes a section, and the slope of each section is determined by the heat generation power P of each membrane element. k , water channel inlet temperature T in and water outlet temperature T out That is to say, the average temperature Tck of cooling water in multiple sub-channels is approximately regarded as a linear change.

[0059] Specifically, step S104 includes:

[0060] Step S104a, based on the power P of multiple membrane elements k , water channel inlet temperature T in and water outlet temperature T out Get the water temperature rise value ΔT of each sub-channel k .

[0061] The calculation formula of water temperature rise ΔTk is as follows:

[0062]

[0063] Here, k is used to indicate the number of membrane elements, i=1, 2, 3, ..., n, and n is the number of membrane elements.

[0064] Step S104b, obtaining the average cooling water temperature T based on the water temperature increase value ΔTk ck .

[0065] Among them, the average temperature of cooling water is T ck The calculation formula is as follows:

[0066]

[0067] After obtaining the average cooling water temperature Tck in step S104, Tck It is regarded as the reference ground of the membrane node of the kth membrane element in the Cauer thermal resistance model, and then the corresponding equivalent circuit model in the simplified thermal model of liquid cooling and heating is obtained.

[0068] Step S106: According to the Cauer model rule, the thermal resistance R o , membrane water thermal resistance R is equivalent to resistance, heat capacity C is equivalent to capacitance, cooling water average temperature difference ΔT between adjacent sub-channels ck Equivalent to a voltage source, the heating power of each membrane element is P k Equivalent to a current source, the average temperature of cooling water in each sub-channel is T ck Equivalent to the membrane node reference ground of the corresponding membrane element, the membrane temperature T of each membrane element pk It is equivalent to the observed quantity and an equivalent circuit model is established.

[0069] Step S108: Obtain the corresponding state space expression according to the equivalent circuit model, and convert the heating power P of the membrane element into k and cooling water average temperature T ck As input, the membrane temperature T pk As the state quantity and output quantity, the membrane temperature T of the membrane element is obtained. pk .

[0070] The state space expression is:

[0071]

[0072] In order to simplify the analysis, it can be assumed that the coupled inter-film thermal resistance R between adjacent film elements is o , the membrane water thermal resistance R between each membrane element and the cooling water of the corresponding sub-channel, and the heat capacity C of each membrane element are approximately equal; since the thermal resistances are all positive numbers, the eigenvalues ​​of the transfer matrix of the state space expression must be negative real numbers, so the state space must be exponentially stable, indicating that when the heating power remains unchanged, the membrane temperature T of the membrane element pk It tends to a constant value, which is consistent with actual experience and also shows that the state space expression of the present application can be used to estimate the membrane temperature of the membrane element.

[0073] The specific implementation steps of the embodiment of the present invention are as follows:

[0074] Model establishment: Establish the thermal impedance model of the observed liquid-cooled heater, such as Figure 4 As shown, each independently controllable part (membrane element) of the heating film and the water channel (sub-water channel) below it are regarded as a thermal unit, all independently controllable parts and the entire water channel can be regarded as a parallel connection of multiple thermal units with the same structure, and each independently controlled part of the heating film is coupled by thermal resistance.

[0075] The water temperature rise under each membrane element (water temperature rise value) is proportional to the heat generation power of the membrane element. The sum of the water temperature rise under all membrane elements is equal to the inlet and outlet temperature difference (water channel inlet temperature T in and the water channel outlet temperature T out The average temperature T of the cooling water in the sub-channels under each membrane element can be obtained recursively. ck .

[0076] Model equivalence: According to the rules of the Cauer model, the above-mentioned structure of multiple membrane nodes + inter-membrane nodes in parallel is equivalent to a circuit model, such as Figure 5 As shown. Each thermal resistance (film-water thermal resistance R between the film and water, and film-to-film coupling thermal resistance R o ) is equivalent to resistance, heat capacity (heat capacity of membrane itself C) is equivalent to capacitance, and the average temperature difference of cooling water between the average temperature of the water channel under each two adjacent membranes is T ck -T c(k-1) Equivalent to a voltage source, the heating power P of each heating film k Equivalent to a current source, the average water temperature under each membrane is T ck It is equivalent to the reference ground of the membrane node. The temperature of each membrane T pk is the observed quantity. Each part in the equivalent circuit has a clear physical meaning.

[0077] Temperature observation: Establish the state space expression corresponding to the above equivalent circuit model, take the heating power and the water temperature at the inlet and outlet of the water channel as input quantities, and the membrane temperature of the membrane element as the state quantity and output quantity to realize the estimation of the heating film temperature of the liquid-cooled heater.

[0078] In summary, this method can realize open-loop observation of the temperature of each part of the heating film under the condition of only the inlet and outlet temperatures and the power information of each part of the heating film, where the temperature at different positions of the water channel is approximately regarded as a linear change, and the thermal resistance between each independently controlled part of the heating film is considered.

[0079] Example 2

[0080] The temperature estimation method of the present invention is further explained below by taking the membrane elements of the liquid-cooled heater as two examples.

[0081] like Figures 7-10 As shown, the heating power of the two membrane elements is independent of each other, but the temperature is not independent. There is a thermal resistance coupling R between the contact surfaces of the two. 12 There is also a thermal resistance R between each membrane and water, and the membrane itself also has a heat capacity C. Based on this, it can be concluded that Figure 2 Thermal model parameters of each part of the model, such as Figure 3 In addition to the thermal resistance and capacitance parameters, P1 and P2 are the thermal powers of the two membrane resistors, T p1 and T p2are the temperature observation values ​​of the two membrane resistors, T1 and T2 are the water temperature measurements at the inlet and outlet, T c1 and T c2 They are the average temperature of cooling water under the resistance of two membrane elements.

[0082] Since the specific heat capacity of water is very large, the water temperature is very different from the temperature of the heating element. Therefore, the cooling water temperature can be approximated as a piecewise linear function of the distance through the water channel. Each heating element constitutes a section, and the slope of each section is determined by the power ratio of each heating element and the temperature difference between the inlet and outlet of the water channel T2-T1 (T2 is the outlet temperature of the water channel, and T1 is the inlet temperature of the water channel). Then, the average temperature of the cooling water under the two membrane elements can be obtained. c1 and T c2 The approximate expression of is:

[0083]

[0084] It can be further known that the temperature difference between the average water temperatures under the two membranes is:

[0085] T c2 -T c1 =(T2-T1) / 2

[0086] After obtaining the above relationship, T c1 and T c2 is regarded as the reference ground in the Cauer thermal resistance model, and then the equivalent circuit model corresponding to the simplified thermal model of the liquid-cooled heater is obtained, as shown in Figure 4 As shown. The state space expression of the model is:

[0087]

[0088] To simplify the analysis, it is assumed that the thermal resistance and heat capacity of the two membranes are equal, but the applicability of this method is not limited to this case. Since the thermal resistances are both positive, the two eigenvalues ​​of the state transfer matrix in this state space must be negative real numbers, so the state space must be exponentially stable, indicating that when the power is constant, T p1 and T p2 will tend to a constant value, which is consistent with actual experience. Figure 5 This is the input and output diagram of the state space.

[0089] A temperature estimation method of the present invention establishes a state-space expression of a thermal impedance model equivalent to a circuit model, thereby only needing to measure the inlet and outlet temperatures, and without considering the electrical characteristics of the heating element during observation, and can also perform open-loop observation in the absence of feedback conditions.

[0090] In this specification, the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the product embodiment described later, since it corresponds to the method, the description is relatively simple, and the relevant parts can be referred to the partial description of the system embodiment.

[0091] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A temperature estimation method, characterized in that: Applied to a liquid-cooled heater, the liquid-cooled heater comprises a water channel and a plurality of membrane elements sequentially laid on the water channel, the temperature estimation method comprises: The plurality of membrane elements and the sub-water channels below the plurality of membrane elements are regarded as a plurality of thermal units connected in parallel in sequence to establish a thermal impedance model of the liquid-cooled heater, wherein the thermal impedance model includes the coupled membrane inter-thermal resistance R between adjacent membrane elements. o , the membrane-water thermal resistance R between each of the membrane elements and the cooling water in the corresponding sub-channel, and the heat capacity C of each of the membrane elements; Based on the power of the membrane elements, the water channel inlet temperature T in and water outlet temperature T out Get the average cooling water temperature T of each sub-channel ck (k=1, 2, 3, ..., n); According to the Cauer model rule, the coupling film thermal resistance R o , the membrane water thermal resistance R is equivalent to a resistor, the heat capacity C is equivalent to a capacitor, and the cooling water average temperature difference ΔT between adjacent sub-channels ck Equivalent to a voltage source, the heating power P of each membrane element k Equivalent to a current source, the average temperature of the cooling water in each sub-channel is T ck is equivalent to the membrane node reference ground of the corresponding membrane element, the membrane temperature T of each membrane element pk Equivalent to the observed quantity, and establish an equivalent circuit model; The corresponding state space expression is obtained according to the equivalent circuit model, and the heating power Pk of the membrane element and the average temperature T ck As input, the membrane temperature T pk As the state quantity and output quantity, the membrane temperature T of the membrane element is obtained. pk .

2. The temperature estimation method according to claim 1, characterized in that: Each of the membrane elements and the sub-water channel corresponding to the membrane element constitutes a thermal unit.

3. The temperature estimation method according to claim 2, characterized in that: The average temperature T of the cooling water in the plurality of sub-water channels ck Myopia is a linear change.

4. The temperature estimation method according to claim 3, characterized in that: The coupling inter-film thermal resistance R between adjacent film elements o , the membrane-water thermal resistance R between each membrane element and the cooling water in the corresponding sub-channel, and the heat capacity C of each membrane element are approximately equal.

5. The temperature estimation method according to claim 1, characterized in that: The power of the plurality of membrane elements, the water channel inlet temperature T in and water outlet temperature T out Get the average cooling water temperature T of each sub-channel ck include: Based on the power P of multiple membrane elements k , water channel inlet temperature T in and water outlet temperature T out Obtain the water temperature rise value ΔT of each sub-water channel k ; Based on the water temperature increase value ΔT k Get the average cooling water temperature T ck .

6. The temperature estimation method according to claim 5, characterized in that: The water temperature rise value ΔT k The calculation formula is as follows: Wherein, k is used to indicate the number of the membrane elements, i=1, 2, 3, ..., n, and n is the number of the membrane elements.

7. The temperature estimation method according to claim 6, characterized in that: The calculation formula of the cooling water average temperature is as follows:

8. The temperature estimation method according to claim 4, characterized in that: The state space expression is:

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