A coolant flow rate estimation method, device, and dual-motor control system

Abstract

The present invention provides a coolant flow rate estimation method, device and dual-motor control system, which relates to the technical field of motor control and is applied to a dual-motor controller. The method includes: obtaining the positions and temperatures of six reference points corresponding to the layout of each three-phase power module in the cooling channel of the dual-motor controller, and obtaining the losses under each power module; respectively estimating the coolant flow rate based on the temperature change rates and corresponding losses of the three-phase power module controlled by the first motor and the three-phase power module controlled by the second motor to obtain a first estimated value and a second estimated value; respectively estimating the coolant flow rate based on the total temperature change amounts and corresponding losses of the three-phase power module controlled by the first motor, the three-phase power module controlled by the second motor, and all power modules to obtain a third estimated value, a fourth estimated value and a fifth estimated value; weighting each estimated value to generate a target result, so as to solve the problem of insufficient accuracy of the coolant flow rate estimation result of the existing dual-motor controller.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a coolant flow estimation method, device and dual-motor control system. Background Art

[0002] The drive system is one of the core components of the car, which determines the safety, economy, and environmental protection of electric vehicles to a certain extent. In the drive system, heat dissipation design plays a vital role in the reliable operation of the vehicle. If there is local overheating in the drive system, it is easy to cause power devices to be damaged due to thermal fatigue, thus affecting the performance of the entire vehicle. Automotive coolant plays an important role in the car. It can take away the excess heat generated by the system and make the drive system run at normal operating temperature.

[0003] At present, most cooling systems use a fixed large flow rate to cool the drive system. The cooling water pump is always running at high power. Generally, a PWM water pump or a switch water pump is used to control the coolant flow rate. Most of them do not have a flow sensor for measurement and use open-loop control. When the dual-motor controller does not have a flow sensor, it is impossible to accurately obtain the cooling water flow rate in real time. Most flow estimates rely only on the absolute deviation of the temperature of a few measurement points, which is easily affected by chance, so the estimation results are less accurate. Summary of the invention

[0004] In order to overcome the above technical defects, the purpose of the present invention is to provide a coolant flow estimation method, device and dual-motor control system to solve the problem of insufficient accuracy of coolant flow estimation results of existing dual-motor controllers.

[0005] The present invention discloses a coolant flow estimation method, which is applied to a dual-motor controller, comprising:

[0006] Obtain the positions and temperatures of six reference points corresponding to the three-phase power modules in the cooling channel of the dual-motor controller, including the first reference point, the second reference point and the third reference point corresponding to the first motor control three-phase power module and the fourth reference point, the fifth reference point and the sixth reference point corresponding to the second motor control three-phase power module; obtain the loss under each power module;

[0007] Based on the temperature change rate and corresponding loss of the first motor control three-phase power module and the second motor control three-phase power module, respectively, the coolant flow rate is estimated to obtain a first estimated value and a second estimated value;

[0008] Based on the first motor controlled three-phase power module, the second motor controlled three-phase power module, the total temperature change of all power modules and the corresponding losses, the coolant flow rate is estimated to obtain a third estimated value, a fourth estimated value and a fifth estimated value;

[0009] Weight the first estimated value, the second estimated value, the third estimated value, the fourth estimated value, and the fifth estimated value to generate a target result.

[0010] Preferably, estimating the coolant flow rates respectively based on the temperature change rates and the corresponding losses of the first motor control three-phase power module and the second motor control three-phase power module to obtain the first estimated value and the second estimated value includes:

[0011] Using the least squares method to perform linear fitting based on the positions and temperatures of the first reference point, the second reference point, and the third reference point to obtain the first slope of the temperature relative position change curve under the first motor control three-phase power module;

[0012] Using the least squares method to perform linear fitting based on the positions and temperatures of the fourth reference point, the fifth reference point, and the sixth reference point to obtain the second slope of the temperature relative position change curve under the second motor control three-phase power module;

[0013] Calculate the first estimated value and the second estimated value respectively based on the first slope, the second slope, and the corresponding total losses according to the preset relationship between the slope and the flow rate function.

[0014] Preferably, the preset relationship between the slope and the flow rate function is set to determine the coolant flow rate according to the ratio of the total loss corresponding to each reference point, the product of the slope and the distance along the cooling channel between the reference points.

[0015] Preferably, the preset relationship between the slope and the flow rate function is set as:

[0016] where Ploss (l,...,m) is the total loss corresponding to the l-th reference point to the m-th reference point; (x m -x l ) is the distance along the cooling channel of the m-th reference point relative to the l-th reference point, ξ is a preset first parameter; k i is the slope, F i is the i-th estimated value; where, i = {1, 2}; l = {1, 2, 3, 4, 5, 6}; m = {1, 2, 3, 4, 5, 6}.

[0017] Preferably, estimating the coolant flow rates respectively based on the temperature change amounts and the corresponding losses of the first motor control three-phase power module, the second motor control three-phase power module, and all the power modules in total to obtain the third estimated value, the fourth estimated value, and the fifth estimated value includes:

[0018] Determine the temperature change amount corresponding to the first motor control three-phase power module based on the temperatures of the first reference point and the third reference point;

[0019] Determine the corresponding temperature change amount of the second motor control three-phase power module based on the temperatures of the fourth reference point and the sixth reference point;

[0020] Determine the total temperature change amount of all power modules based on the temperatures of the first reference point and the sixth reference point;

[0021] Based on the preset temperature difference and flow function relationship, calculate respectively based on the corresponding temperature change amount and total loss of the first motor control three-phase power module, the corresponding temperature change amount and total loss of the second motor control three-phase power module, and the total temperature change amount and total loss of all power modules to obtain the third estimated value, the fourth estimated value, and the fifth estimated value.

[0022] Preferably, the preset temperature difference and flow function relationship is set to determine the coolant flow rate according to the ratio of the total loss, relative temperature change amount, coolant density, and coolant specific heat capacity corresponding to each reference point.

[0023] Preferably, the preset temperature difference and flow function relationship is set as:

[0024] where Ploss (l,…,m) is the total loss corresponding to the l-th reference point to the m-th reference point; ρ is the coolant density; C is the coolant specific heat capacity; T (l,…,m) is the temperature difference corresponding to the l-th reference point to the m-th reference point, F i is the i-th estimated value; where i = {3, 4, 5}; l = {1, 2, 3, 4, 5, 6}; m = {1, 2, 3, 4, 5, 6}.

[0025] Preferably, a mapping table is pre-set, and the mapping table includes the losses corresponding to each power module under different voltages and currents;

[0026] Obtain the real-time current and real-time voltage, and obtain the total loss corresponding to different reference points according to the mapping table.

[0027] The present invention also provides a coolant flow rate estimation device, including:

[0028] A preprocessing module, configured to obtain the positions and temperatures of six reference points corresponding to the layout of each three-phase power module in the cooling channel of the dual-motor controller, including the first reference point, the second reference point, and the third reference point corresponding to the first motor control three-phase power module, and the fourth reference point, the fifth reference point, and the sixth reference point corresponding to the second motor control three-phase power module; obtain the losses under each power module;

[0029] The first calculation module is configured to estimate the coolant flow rate respectively based on the temperature change rates and the corresponding losses of the first motor control three-phase power module and the second motor control three-phase power module, and obtain a first estimated value and a second estimated value;

[0030] The second calculation module is configured to estimate the coolant flow rate respectively based on the first motor control three-phase power module, the second motor control three-phase power module, the total temperature change amount of all power modules and the corresponding losses, and obtain a third estimated value, a fourth estimated value and a fifth estimated value;

[0031] The third calculation module is configured to weight the first estimated value, the second estimated value, the third estimated value, the fourth estimated value and the fifth estimated value to generate a target result.

[0032] The present invention also provides a dual-motor control system applying the above coolant flow rate estimation device.

[0033] After adopting the above technical solution, compared with the prior art, the following beneficial effects are achieved:

[0034] A coolant flow rate estimation method, device and dual-motor control system provided by the present application acquire the real-time sampled temperatures of NTCS placed at 6 locations (i.e., 6 reference points) of the power modules of the dual-motor controller, determine the temperature change rate and the temperature change amount, etc., and also acquire the losses corresponding to the power modules under each reference point. Based on the temperature change and the losses, the coolant flow rate is estimated under different temperature characteristics, and the results estimated under each temperature characteristic are weighted to solve the problem that the accuracy of the coolant flow rate estimation result of the existing dual-motor controller is insufficient. Description of the Drawings

[0035] Figure 1 It is a flowchart of the first embodiment of a coolant flow rate estimation method according to the present invention;

[0036] Figure 2 It is a flowchart of obtaining the first estimated value and the second estimated value in the first embodiment of a coolant flow rate estimation method according to the present invention;

[0037] Figure 3 It is a flowchart of obtaining the third estimated value, the fourth estimated value and the fifth estimated value in the first embodiment of a coolant flow rate estimation method according to the present invention;

[0038] Figure 4 It is a schematic diagram of modules of the second embodiment of a coolant flow rate estimation device according to the present invention.

[0039] Reference Signs:

[0040] 5 - coolant flow rate estimation device; 51 - preprocessing module; 52 - first calculation module; 53 - second calculation module; 54 - third calculation module. Detailed Implementation Modes

[0041] The advantages of the present invention will be further elaborated below in conjunction with the accompanying drawings and specific embodiments.

[0042] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation modes described in the following exemplary embodiments do not represent all implementation modes consistent with the present disclosure. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0043] The terms used in the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The singular forms "a", "the", and "said" used in the present disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0044] It should be understood that although the terms first, second, third, etc. may be used in the present disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present disclosure, depending on the context, the word "if" as used herein can be interpreted as "when" or "while" or "in response to determining".

[0045] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0046] In the description of the present invention, unless otherwise specified and defined, it should be noted that the terms "mounted", "connected", and "coupled" should be understood in a broad sense. For example, they can be mechanical connections or electrical connections, or the internal communication of two elements. They can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0047] In the following description, suffixes such as "module", "component", or "unit" used to denote elements are only for the convenience of explaining the present invention and have no specific meaning in themselves. Therefore, "module" and "component" can be used interchangeably.

[0048] Embodiment 1: This embodiment discloses a coolant flow rate estimation method applied to a dual-motor controller. The method provided in this embodiment is based on the temperature sampling information at 6 locations on the series water channel of the dual-motor controller, and weights and averages the estimation results corresponding to 5 temperature characteristics to improve the accuracy of the estimation results. Specifically, refer to Figure 1 , including:

[0049] S100: Obtain the positions and temperatures of six reference points corresponding to the arrangements of each three-phase power module in the cooling channel of the dual-motor controller, including the first reference point, the second reference point, and the third reference point corresponding to the first motor control three-phase power module, and the fourth reference point, the fifth reference point, and the sixth reference point corresponding to the second motor control three-phase power module; obtain the losses under each power module;

[0050] Specifically, in this embodiment, the dual-motor controller includes two motor controls (the first motor control and the second motor control as described below), and each motor control corresponds to a three-phase power module, which is equivalent to 3 single-phase power modules, for a total of 6 single-phase power modules. A reference point is set for each single-phase power module. It should be noted that the 3 single-phase power modules corresponding to each motor control are arranged in series in the cooling channel, and the two motor controls can be connected in series or in parallel. The positions of the above reference points refer to the specific positions of the reference points relative to the total length of the cooling channel starting from the water inlet. The above temperature is the NTC temperature, which can be directly obtained by using the NTC sensor provided thereon, thereby ensuring the accuracy of the collected data and improving the accuracy of the subsequent estimation of the cooling water flow rate. It should also be explained that for the convenience of expression, the first reference point, the second reference point, and the third reference point, and the fourth reference point, the fifth reference point, and the sixth reference point are described as the reference points arranged in sequence.

[0051] The losses under the above power module are related to current and voltage. Specifically, the losses include but are not limited to conduction losses, switching losses, etc., which are related to the real-time current and real-time voltage passing through the power module. Specifically, they can be calculated in advance / real-time in the following manner: P loss = i·v+(E on +E off +E rr )·f, where i is the voltage, v is the current, f is the loss parameter; E on , E off , E rrThe conduction loss and switching loss. Optionally, a mapping table can be preset. The mapping table includes the losses corresponding to each power module under different voltages and currents. Obtain the real-time current and real-time voltage, and directly obtain the losses corresponding to different reference points (i.e., each power module) according to the mapping table.

[0052] S200: Estimate the coolant flow rates based on the temperature change rates and the corresponding losses of the three-phase power modules controlled by the first motor and the three-phase power modules controlled by the second motor respectively, and obtain a first estimated value and a second estimated value.

[0053] In this embodiment, five temperature characteristics are used to estimate the cooling water flow rate, including the temperature change rate, the temperature change amount, and the total temperature change amount of each reference point of the power module under each motor control. The temperature change rate characterizes the speed of the cooling water temperature change, and can be realized by establishing the temperature change curve of each reference point and fitting the curve to calculate the curve slope.

[0054] Specifically, the above-mentioned estimation of the coolant flow rates based on the temperature change rates and the corresponding losses of the three-phase power modules controlled by the first motor and the three-phase power modules controlled by the second motor respectively, and obtaining a first estimated value and a second estimated value, refer to Figure 2 , including:

[0055] S210: Use the least squares method to perform linear fitting based on the positions and temperatures of the first reference point, the second reference point, and the third reference point, and obtain the first slope of the temperature relative to the position change.

[0056] It should be noted that the least squares method finds the best function matching of the data by minimizing the sum of the squares of the errors. The least squares method can be used to simply obtain the unknown data and make the sum of the squares of the errors between the obtained data and the actual data the smallest. The least squares method can be used for curve fitting. In this embodiment, the curve fitted for each three-phase power module controlled by a motor is a straight line, that is, the fitting straight line formula is set as: T = kx + b, where x is the position of each reference point, T is the temperature of each reference point, and k is the slope, that is, the above-mentioned temperature change rate.

[0057] S220: Use the least squares method to perform linear fitting based on the positions and temperatures of the fourth reference point, the fifth reference point, and the sixth reference point, and obtain the second slope of the temperature relative to the position change.

[0058] As described above, this step is similar to the fitting in the above S210, and is for determining the temperature change rate under the power module corresponding to different motor controls. Specifically, the fitting expressions of the above first slope and second slope are respectively, as examples:

[0059] Where x here i, where \(i = 1 - 6\), representing the first - sixth reference points respectively, and \(n\) is a fitting parameter.

[0060] S230: Calculate the first estimated value and the second estimated value respectively based on the preset relationship between slope and flow function, based on the first slope, the second slope, and the corresponding total losses respectively.

[0061] After obtaining the first slope and the second slope by fitting according to the above steps S210 - S220, estimation can be carried out according to the relationship between the temperature change rate and the cooling water flow (i.e., the above - mentioned preset relationship between slope and flow function). Specifically, the preset relationship between slope and flow function is set to determine the coolant flow according to the ratio of "the total loss corresponding to each reference point" to "the product of the slope and the distance along the cooling channel between the reference points", and the loss is determined according to each power module and its corresponding real - time current and real - time voltage. It should be noted that for the total loss corresponding to each of the above - mentioned reference points, different slopes correspond to the sum of losses at different reference points. For example, the first slope corresponds to the sum of losses at the first reference point, the second reference point, and the third reference point.

[0062] Furthermore, the preset relationship between slope and flow function is set as:

[0063] where \(P_{loss}\) (l,…,m) is the total loss corresponding to the \(l\) - th reference point to the \(m\) - th reference point; \((x m - x l ) is the distance along the cooling channel of the \(m\) - th reference point relative to the \(l\) - th reference point, \(\xi\) is a preset first parameter, which can be pre - calibrated through simulation experiments or platforms; \(k i is the slope, \(F i is the \(i\) - th estimated value; where \(i=\{1,2\}\); \(l = \{1,2,3,4,5,6\}\); \(m=\{1,2,3,4,5,6\}\).

[0064] Based on the above formula,

[0065] It should be noted that \(P_{loss}\) (1,2,3) and \(P_{loss}\) (4,5,6) are respectively the total losses at the corresponding reference point positions.

[0066] Optionally, in order to facilitate the calculation of the above and below-mentioned respective estimated values and improve the calculation efficiency, a mapping table may be preset. The mapping table includes the losses corresponding to each power module under different voltages and currents. Obtain the real-time current and real-time voltage, and obtain the losses corresponding to different reference points according to the mapping table. By way of example and not limitation, when calculating the first estimated value above, directly obtain the losses corresponding to the first reference point, the second reference point, and the third reference point from the mapping table according to the real-time current and real-time voltage, and sum them up, which can be used for the calculation in the above-mentioned preset slope and flow function relationship.

[0067] S300: Based on the temperature change amounts and corresponding losses of the three-phase power module controlled by the first motor, the three-phase power module controlled by the second motor, and all power modules, respectively estimate the coolant flow rates to obtain the third estimated value, the fourth estimated value, and the fifth estimated value;

[0068] In the above step S200, the coolant flow rate is estimated according to the temperature change rate under the corresponding losses in the first motor control and the second motor control. In this step, the coolant flow rate is estimated based on the temperature change amount under the loss. Specifically, based on the temperature change amounts and corresponding losses of the three-phase power module controlled by the first motor, the three-phase power module controlled by the second motor, and all power modules, respectively estimate the coolant flow rates to obtain the third estimated value, the fourth estimated value, and the fifth estimated value. Refer to Figure 3 , including:

[0069] S310: Determine the temperature change amount corresponding to the three-phase power module controlled by the first motor based on the temperatures of the first reference point and the third reference point;

[0070] In the above step, that is, the temperature of the third reference point minus the temperature of the first reference point is the temperature change amount corresponding to the first motor control.

[0071] S320: Determine the temperature change amount corresponding to the three-phase power module controlled by the second motor based on the temperatures of the fourth reference point and the sixth reference point;

[0072] In the above step, the temperature of the sixth reference point minus the temperature of the fourth reference point is the temperature change amount corresponding to the second motor control.

[0073] S330: Determine the total temperature change amount of all power modules based on the temperatures of the first reference point and the sixth reference point;

[0074] In the above step, the temperature of the sixth reference point minus the temperature of the first reference point is the total temperature change amount.

[0075] S340: According to the preset temperature difference and flow rate function relationship, the third estimated value, the fourth estimated value and the fifth estimated value are obtained based on the corresponding temperature change and total loss of the three-phase power module controlled by the first motor, the corresponding temperature change and total loss of the three-phase power module controlled by the second motor, and the total temperature change and total loss of all power modules.

[0076] The above preset temperature difference and flow function relationship represents the change of the corresponding coolant flow rate as the temperature changes. Specifically, the preset temperature difference and flow function relationship is set to determine the coolant flow rate based on the ratio of "the total loss corresponding to each reference point" to "the temperature change, the coolant density and the coolant specific heat capacity", wherein the loss is determined based on each power module and its corresponding real-time current and real-time voltage. The above coolant density and coolant specific heat capacity are determined in advance based on the coolant used. For example, the coolant density = 1 and the coolant specific heat capacity = 3686.

[0077] Specifically, the above preset temperature difference and flow rate function relationship is set to be expressed as follows:

[0078] Among them, Ploss (l,…,m) is the sum of the losses corresponding to the lth reference point to the mth reference point; ρ is the coolant density; C is the specific heat capacity of the coolant; T (l,…,m) is the temperature difference between the lth reference point and the mth reference point, F i is the i-th estimated value; wherein, i={3,4,5}; l={1,2,3,4,5,6}; m={1,2,3,4,5,6}; in the above expression, 60 is a constant parameter.

[0079] Referring to the above step S230, a mapping table may be pre-set, the mapping table including the losses corresponding to each power module under different voltages and currents; real-time current and real-time voltage are obtained, and the sum of losses corresponding to different reference points is obtained according to the mapping table. As an example but not a limitation, when calculating the third estimated value, the losses corresponding to the first reference point, the second reference point and the third reference point are directly obtained from the mapping table according to the real-time current and the real-time voltage, and the sum is added. The fourth estimated value corresponds to the sum of losses corresponding to the third reference point, the fourth reference point and the fifth reference point, and the fifth estimated value corresponds to the sum of losses corresponding to all reference points.

[0080] As an example, based on the above expression,

[0081] Here T 1 , T 2 , T 3They are the temperature change amounts corresponding to the three-phase power modules of the first motor control, the temperature change amounts corresponding to the three-phase power modules of the second motor control, and the total temperature change amount of all power modules, respectively.

[0082] S400: Weight the first estimated value, the second estimated value, the third estimated value, the fourth estimated value, and the fifth estimated value to generate a target result.

[0083] In this embodiment, based on the above step S100, the positions and temperatures of six reference points of the corresponding power modules in the dual-motor controller are collected. In the above steps S200 - S300, based on the positions and temperatures of each reference point, the coolant flow rate is estimated respectively based on different temperature change rates and temperature change amounts, and five temperature characteristics are obtained (such as the temperature change rate corresponding to the three-phase power module of the first motor control, the temperature change rate corresponding to the three-phase power module of the second motor control, the temperature change amount corresponding to the three-phase power module of the first motor control, the temperature change amount corresponding to the three-phase power module of the second motor control, and the total temperature change amount). In this step, each temperature characteristic is weighted to obtain the final estimated result (i.e., the above target result). Specifically, weights corresponding to each temperature characteristic (i.e., the above first estimated value - fifth estimated value) can be preset, that is, F = s 1 ·F 1 +s 2 ·F 2 +s 3 ·F 3 +s 4 ·F 4 +s 5 ·F 5 . Among them, s 1 +s 2 +s 3 +s 4 +s 5 = 1; s 1 、s 2 、s 3 、s 4 、s 5 are the weights corresponding to the first estimated value, the second estimated value, the third estimated value, the fourth estimated value, and the fifth estimated value respectively. Their specific values are obtained through experimental calibration for different application scenarios. Larger weights are set for temperature characteristics that have a greater impact on the coolant flow rate.

[0084] In this embodiment, the losses at the power module 6 of the dual-motor controller are obtained, and the real-time sampled temperatures and positions of the NTCs placed at the power module 6 (i.e., 6 reference points) are obtained; the cooling water flow rate is estimated in real time based on the data collected at the 6 reference points; the corresponding losses, temperature change rates, and temperature change amounts of the first motor control three-phase power module, the second motor control three-phase power module, the total loss, and the total temperature change amount are analyzed in real time, and the corresponding estimated cooling water flow rates (i.e., the first estimated value - the fifth estimated value) are obtained. According to their corresponding different weights, the above various flow rate estimation results F 1 -F 5 are weighted and averaged to obtain the real-time flow rate estimation value, that is, the target result. Based on the temperature sampling at 6 locations on the cooling water channel of the dual-motor controller, the estimation results corresponding to 5 temperature characteristics are weighted and averaged, which is different from the existing situation where the temperature is obtained from only 1-2 sampling points for estimation and cannot be used for the estimation of the coolant flow rate of the dual-motor controller. In this application, multiple temperature differences and temperature change rates are set to estimate the cooling water flow rate separately under different temperature characteristics and then weighted, so as to solve the problem of insufficient accuracy of the existing estimation results of the coolant flow rate of the dual-motor controller.

[0085] Embodiment 2: The present invention also provides a coolant flow rate estimation device 5. Refer to Figure 4 , including:

[0086] A preprocessing module 51, configured to obtain the positions and temperatures of six reference points corresponding to each three-phase power module arranged in the cooling channel of the dual-motor controller, including a first reference point, a second reference point, and a third reference point corresponding to the first motor control three-phase power module, and a fourth reference point, a fifth reference point, and a sixth reference point corresponding to the second motor control three-phase power module; obtain the losses under each power module;

[0087] In the above module, the dual-motor controller includes two motor controls, and each motor control corresponds to a three-phase power module, that is, 3 power modules, a total of 6 power modules. A reference point is set for each power module. It should be noted that the 3 single-phase power modules corresponding to each motor control are connected in series, and the two motor controls can be connected in series or in parallel. Temperature sampling is performed at each reference point to obtain the above temperatures for the following various modules to perform data processing and then estimate the coolant flow rate.

[0088] As an illustration, the losses in the following first calculation module and the second calculation module are all the conduction losses, switching losses, etc. generated by each power module under different currents and voltages, which can be calculated based on the real-time current and real-time voltage according to a preset loss formula, or a mapping table can be set in advance, which contains the losses of each power module under different voltages and currents, and the losses can be obtained by matching the mapping table during the calculation process.

[0089] The first calculation module 52 is configured to estimate the coolant flow rate based on the first motor control three-phase power module, the second motor control three-phase power module, the total temperature change of all power modules, and the corresponding losses respectively, to obtain a third estimated value, a fourth estimated value, and a fifth estimated value.

[0090] Specifically, the least squares method is used to fit a straight line corresponding to each motor control three-phase power module, and the temperature change rate corresponding to each motor control is determined according to the slope of the straight line. Then, the flow rate is determined according to the ratio of the sum of the losses corresponding to each reference point under each motor control to the product of the slope of its fitting curve and the distance along the cooling channel between the reference points, so as to estimate the coolant flow rate, and the above-mentioned first estimated value and second estimated value corresponding to the two motor controls are obtained respectively.

[0091] The second calculation module 53 is configured to estimate the coolant flow rate based on the first motor control three-phase power module, the second motor control three-phase power module, the total temperature change of all power modules, and the corresponding losses respectively, to obtain a third estimated value, a fourth estimated value, and a fifth estimated value.

[0092] Specifically, the temperature change amounts of the two motor controls and the total process are determined respectively, and the flow rate is determined according to the ratio of the sum of the losses corresponding to each reference point to the temperature change amount, the coolant density, and the specific heat capacity of the coolant. The coolant density, specific heat capacity, etc. can be obtained in advance according to the coolant type.

[0093] The third calculation module 54 is configured to weight the first estimated value, the second estimated value, the third estimated value, the fourth estimated value, and the fifth estimated value to generate a target result.

[0094] Specifically, in the above module, weights corresponding to each temperature feature (i.e., the above first estimated value - fifth estimated value) can be preset, different weight values are set according to the different degrees of influence of each temperature feature on the coolant flow rate, and based on 6 temperature samplings on the cooling water channel of the dual motor controller, temperature features are generated based on multiple different temperature differences, temperature change rates, and the corresponding losses, and then the coolant flow rate is estimated respectively and weighted to solve the problem of insufficient accuracy of the existing coolant flow rate estimation result of the dual motor controller.

[0095] Embodiment 3: The present invention further provides a dual-motor control system. Applying the above coolant flow rate estimation device, it further includes other devices or apparatuses for realizing the operation of the system, including but not limited to the above motor controller, drive module, etc. The coolant flow rate estimation device is used to obtain the losses at the power module 6 of the dual-motor controller, obtain the real-time sampled temperatures of the NTCs placed at the power module 6 (i.e., 6 reference points), determine the temperature change rate and temperature change amount, etc. Based on this, multi-dimensional (temperature characteristics) estimation of the coolant flow rate is performed, and the results estimated under each dimension are weighted to achieve the estimation of the coolant flow rate in the dual-motor controller, improving the accuracy of the estimation results.

[0096] It should be noted that the embodiments of the present invention have good implementability and do not impose any form of limitation on the present invention. Any person skilled in the art may use the disclosed technical content to modify or transform it into an equivalent effective embodiment. However, as long as it does not depart from the technical solution of the present invention, any modification, equivalent change, or modification made to the above embodiments based on the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A coolant flow rate estimation method, characterized in that, applied to a dual-motor controller, including: Obtain the positions and temperatures of six reference points corresponding to the layout of each three-phase power module in the cooling channel of the dual-motor controller, including the first reference point, the second reference point, and the third reference point corresponding to the first motor control three-phase power module, and the fourth reference point, the fifth reference point, and the sixth reference point corresponding to the second motor control three-phase power module; obtain the losses under each power module; Based on the temperature change rates and corresponding losses of the first motor control three-phase power module and the second motor control three-phase power module, respectively estimate the coolant flow rate to obtain a first estimated value and a second estimated value; Based on the first motor control three-phase power module, the second motor control three-phase power module, the total temperature change of all power modules, and the corresponding losses, respectively estimate the coolant flow rate to obtain a third estimated value, a fourth estimated value, and a fifth estimated value; Weight the first estimated value, the second estimated value, the third estimated value, the fourth estimated value, and the fifth estimated value to generate a target result.

2. The flow rate estimation method according to claim 1, characterized in that, The step of respectively estimating the coolant flow rate based on the temperature change rates and corresponding losses of the first motor control three-phase power module and the second motor control three-phase power module to obtain a first estimated value and a second estimated value includes: Using the least squares method to perform linear fitting based on the positions and temperatures of the first reference point, the second reference point, and the third reference point to obtain the first slope of the temperature relative position change curve under the first motor control three-phase power module; Using the least squares method to perform linear fitting based on the positions and temperatures of the fourth reference point, the fifth reference point, and the sixth reference point to obtain the second slope of the temperature relative position change curve under the second motor control three-phase power module; Calculate the first estimated value and the second estimated value respectively based on the preset relationship between the slope and the flow rate function, the first slope, the second slope, and the corresponding total losses.

3. The flow rate estimation method according to claim 2, characterized in that: The preset relationship between the slope and the flow rate function is set to determine the coolant flow rate according to the ratio of the total loss corresponding to each reference point to the product of the slope and the distance along the cooling channel between the reference points.

4. The flow rate estimation method according to claim 3, characterized in that: The preset relationship between the slope and the flow rate function is set as: Among them, Ploss (l,...,m) is the total loss corresponding to the l-th reference point to the m-th reference point; (x m - x l ) is the distance of the m-th reference point relative to the l-th reference point along the cooling channel, and ξ is a preset first parameter; k i is the slope, and F i is the i-th estimated value; where, i = {1, 2}; l = {1, 2, 3, 4, 5, 6}; m = {1, 2, 3, 4, 5, 6}.

5. The flow rate estimation method according to claim 1, characterized in that, The step of respectively estimating the coolant flow rate based on the first motor control three-phase power module, the second motor control three-phase power module, the total temperature change of all power modules, and the corresponding losses to obtain a third estimated value, a fourth estimated value, and a fifth estimated value includes: Determine the temperature change amount corresponding to the first motor control three-phase power module based on the temperatures of the first reference point and the third reference point; Determine the temperature change amount corresponding to the second motor control three-phase power module based on the temperatures of the fourth reference point and the sixth reference point; Determine the total temperature change amount of all power modules based on the temperatures of the first reference point and the sixth reference point; Based on the preset temperature difference and flow function relationship, calculate respectively based on the temperature change amount and total loss corresponding to the three-phase power module controlled by the first motor, the temperature change amount and total loss corresponding to the three-phase power module controlled by the second motor, the total temperature change amount and total loss of all power modules, and obtain the third estimated value, the fourth estimated value and the fifth estimated value.

6. The flow rate estimation method according to claim 5, wherein: the preset temperature difference and flow function relationship is set to determine the coolant flow rate according to the ratio of the total loss, relative temperature change amount, coolant density, and coolant specific heat capacity corresponding to each reference point.

7. The flow rate estimation method according to claim 6, wherein: The preset temperature difference and flow function relationship is set as: where Ploss (l,…,m) is the total loss corresponding to the l-th reference point to the m-th reference point; ρ is the density of the coolant; C is the specific heat capacity of the coolant; T (l,…,m) is the temperature difference corresponding to the l-th reference point to the m-th reference point, F i is the i-th estimated value; where i = {3, 4, 5}; l = {1, 2, 3, 4, 5, 6}; m = {1, 2, 3, 4, 5, 6}.

8. The flow rate estimation method according to claim 2 or 6, wherein: a mapping table is preset, and the mapping table includes the losses corresponding to each power module under different voltages and currents; obtain the real-time current and real-time voltage, and obtain the losses corresponding to different reference points according to the mapping table.

9. A coolant flow rate estimation device, wherein, comprising: a preprocessing module, configured to obtain the positions and temperatures of six reference points corresponding to the arrangement of each three-phase power module in the cooling channels of the dual-motor controller, including the first reference point, the second reference point, and the third reference point corresponding to the three-phase power module controlled by the first motor, and the fourth reference point, the fifth reference point, and the sixth reference point corresponding to the three-phase power module controlled by the second motor; obtain the losses under each power module; a first calculation module, configured to perform coolant flow rate estimation respectively based on the temperature change rates and corresponding losses of the three-phase power module controlled by the first motor and the three-phase power module controlled by the second motor, and obtain a first estimated value and a second estimated value; a second calculation module, configured to perform coolant flow rate estimation respectively based on the temperature change amounts and corresponding losses of the three-phase power module controlled by the first motor, the three-phase power module controlled by the second motor, and the total temperature change amount of all power modules, and obtain a third estimated value, a fourth estimated value, and a fifth estimated value; a third calculation module, configured to weight the first estimated value, the second estimated value, the third estimated value, the fourth estimated value, and the fifth estimated value to generate a target result.

10. A dual-motor control system applying the coolant flow rate estimation device according to claim 9 above.

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