Temperature estimating device for winding field motor

Abstract

To provide a temperature estimating device for a winding field motor in which an error in estimating a rotor coil temperature can be restrained.SOLUTION: A temperature estimating device 9 for a winding field motor 1 calculates an amount of heat generated by a rotor coil 22 of the winding field motor 1 on the basis of temperature information measured by a stator coil temperature sensor 7 that measures temperature of a stator coil 32 of the winding field motor 1 and a refrigerant temperature sensor 6 that measures temperature of a refrigerant R supplied to the winding field motor 1, and calculates initial temperature of the rotor coil 22 on the basis of an operation state after end of previous travelling, and estimates the temperature of the rotor coil 22 on the basis of the amount of generated heat and the initial temperature.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present disclosure relates to a temperature estimation device for a wound field motor. [Background technology]

[0002] To prevent coil insulation breakdown in a wound-field motor, it is necessary to estimate the rotor coil temperature while the vehicle is running and limit the motor load once the temperature exceeds a certain level to prevent insulation breakdown in the rotor.

[0003] Patent Document 1 discloses a method of calculating the electrical resistance of a rotor coil from the voltage and current of a rotor coil field circuit, and estimating the rotor coil temperature from the temperature characteristics of the electrical resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-180414 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional temperature estimation methods such as those described in Patent Document 1, if the error in the voltage and current sensors is large, the estimation error in the rotor coil temperature becomes large, and therefore, even if the rotor coil temperature does not actually exceed the coil heat resistance temperature, a situation may arise in which the motor load (power performance) is limited.

[0006] An object of the present disclosure is to provide a temperature estimation device for a wound-field motor that can reduce estimation errors in the rotor coil temperature. [Means for solving the problem]

[0007] A temperature estimation device for a wound-field motor according to one aspect of an embodiment of the present invention calculates a heat generation amount of a rotor coil of the wound-field motor based on temperature information measured by a stator coil temperature sensor that measures the temperature of a stator coil of the wound-field motor and a refrigerant temperature sensor that measures the temperature of a refrigerant supplied to the wound-field motor, calculates an initial temperature of the rotor coil based on the operating state since the end of the previous running, and estimates the temperature of the rotor coil based on the heat generation amount and the initial temperature. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a temperature estimation device for a wound-field motor that can suppress estimation errors in the rotor winding temperature. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a wound field motor according to an embodiment; [Figure 2] 1 is a block diagram illustrating the simplification of a thermal circuit network according to an embodiment of the present invention. [Figure 3] FIG. 1 is a diagram showing an example of a simplified thermal circuit network according to the present embodiment; [Figure 4] 1 is a flowchart of a temperature prediction method using a simplified thermal network according to the present embodiment. [Figure 5] FIG. 5 is a diagram illustrating an example of a method for estimating the initial temperature in step S1 of FIG. 4. [Figure 6] FIG. 10 is a diagram showing a simplified thermal circuit network according to a first modified example. [Figure 7] FIG. 10 is a diagram showing a simplified thermal circuit network according to a second modified example. [Figure 8] FIG. 10 is a diagram showing a simplified thermal circuit network according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0011] Fig. 1 is a diagram showing the schematic configuration of a wound-field motor 1 according to an embodiment. Fig. 1(A) is a diagram seen from the direction of the motor's axis C, and Fig. 1(B) is a cross-sectional view taken along the line AA in Fig. 1(A). In Fig. 1(B), the left-right direction of the figure corresponds to the direction of the motor's axis C.

[0012] The wound-field motor 1 includes a rotor 2 and a stator 3. The stator 3 is formed in a hollow annular shape, and the rotor 2 is housed in the hollow portion and supported rotatably.

[0013] The rotor 2 has a rotor core 21 and a rotor coil 22. A shaft 4 serving as the drive shaft of the motor is connected to the center of the rotor core 21. The stator 3 has a stator core 31 and a stator coil 32. The wound-field motor 1 actively adjusts the field magnetic flux by passing current through the rotor coil 22 of the rotor 2 and the stator coil 32 of the stator 3, thereby varying the driving force output from the shaft 4.

[0014] The wound-field motor 1 includes a cooling device 5 for cooling the rotor 2 and the stator 3. The cooling device 5 supplies a refrigerant R to the rotor 2 and the stator 3 to cool them. The refrigerant R can be hydraulic oil, such as ATF (Automatic Transmission Fluid). The cooling device 5 includes a rotor cooling pipe 51, a stator cooling pipe 52, a circulation pipe 53, a pump 54, and a heat exchanger 55.

[0015] The rotor cooling pipe 51 supplies the refrigerant R to the rotor coil 22. The stator cooling pipe 52 supplies the refrigerant R to the stator coil 32. The circulation pipe 53 circulates the refrigerant R among the rotor 2 and the stator 3, the pump 54, and the heat exchanger 55. The rotor cooling pipe 51 and the stator cooling pipe 52 are configured as parts of the circulation pipe 53.

[0016] The pump 54 is a drive source for unidirectionally transferring the refrigerant R within the circulation pipe 53. In the example of FIG. 1(A), the heat exchanger 55 performs heat exchange with the refrigerant R that flows within the circulation pipe 53 and that has passed through the rotor 2 and the stator 3 and absorbed heat from the rotor 2 and the stator 3, thereby re-cooling the refrigerant R. In FIG. 1, the flow of the refrigerant R is indicated by arrows.

[0017] The wound-field motor 1 may include a case 10 (see FIG. 2) that houses the rotor 2, stator 3, and other elements, and may have a drain on the bottom of the case that stores the refrigerant R. In this case, the drain is incorporated into a portion of the circulation pipe 53, and a pump 54 draws up the refrigerant R that has passed through the rotor 2 and the stator 3 and is stored in the drain, and supplies it to a heat exchanger 55.

[0018] The wound-field motor 1 of this embodiment includes a refrigerant temperature sensor 6 and a stator coil temperature sensor 7. The refrigerant temperature sensor 6 is installed in the stator cooling pipe 52 and measures the temperature of the refrigerant R flowing inside the stator cooling pipe 52.

[0019] The stator coil temperature sensor 7 is installed in the stator coil 32 and measures the temperature of the stator coil 32. In this embodiment, the stator coil temperature sensor 7 is installed in the lead-side coil end 32A of the coil ends of the stator coil 32 and measures the temperature of the coil end. Note that the stator coil temperature sensor 7 may also be installed in the non-lead-side coil end 32B and measure the temperature of the coil end.

[0020] The wound-field motor 1 is equipped with a control device 8. The control device 8 adjusts the value of the current flowing through the rotor coil 22 and the stator coil 32 to control the field flux and thereby control the motor output. In particular, in this embodiment, the wound-field motor 1 is equipped with a temperature estimation device 9. The temperature estimation device 9 estimates the temperature of each part of the motor based on temperature information measured by the refrigerant temperature sensor 6 and the stator coil temperature sensor 7.

[0021] Based on the temperature information estimated by the temperature estimation device 9, particularly based on the temperature of the rotor coil 22 while the vehicle is running, the control device 8 can perform control to limit the motor load when the rotor coil temperature reaches a certain temperature or higher in order to prevent insulation breakdown of the rotor coil 22.

[0022] The control device 8 and the temperature estimation device 9 can be physically configured as a computer system or control board including a CPU (Central Processing Unit), a main storage device such as RAM (Random Access Memory) and ROM (Read Only Memory), an input device, an output device, a communication module, an auxiliary storage device such as a hard disk, etc. The functions of the control device 8 and the temperature estimation device 9 are realized by loading predetermined computer software onto hardware such as the CPU and RAM, thereby operating the communication module, input device, and output device under the control of the CPU and reading and writing data from and to the RAM and auxiliary storage device. Note that when the wound-field motor 1 according to this embodiment is mounted on a vehicle, the control device 8 and the temperature estimation device 9 may be implemented as part of the vehicle's ECU (Electronic Control Unit).

[0023] In this embodiment, a simple thermal circuit network is constructed from the motor rotation speed, torque, stator coil temperature, and refrigerant temperature to easily estimate the maximum rotor coil temperature while driving, and if the estimated coil temperature is above a threshold value, a load factor restriction is implemented to protect the components.

[0024] Fig. 2 is a block diagram illustrating the simplification of the thermal network 11 in this embodiment. Fig. 2 illustrates an example of the thermal network 11 around the rotor winding 22 in the wound-field motor 1 shown in Fig. 1. In this embodiment, the following simplifications (1) to (3) are implemented for the thermal network shown in Fig. 2, thereby enabling simple and highly accurate temperature estimation of the rotor winding temperature. Note that the numbers (1), (2), and (3) in Fig. 2 correspond to the following simplification methods (1) to (3), respectively.

[0025] (1) Use of stator coil temperature sensor 7 The stator coil temperature sensor 7 mounted on the lead-side coil end 32A or the anti-lead-side coil end 32B of the stator coil 32 is set as the boundary temperature. In the example of FIGS. 1 and 2, the stator coil temperature sensor 7 is installed at the lead-side coil end 32A to measure the temperature of the lead-side coil end 32A, and measurement at the anti-lead-side coil end 32B is omitted. The temperature measured by the stator coil temperature sensor 7 is also substituted for the temperature of the coil end on the side where the stator coil temperature sensor 7 is not mounted. In the example of FIGS. 1 and 2, the temperature of the anti-lead-side coil end 32B is also substituted for the temperature of the lead-side coil end 32A measured by the stator coil temperature sensor 7. This makes it possible to omit temperature calculations for the thermal circuit up to the drain ATF (the refrigerant that collects in the drain at the bottom of the motor case).

[0026] (2) Substitute case temperature with refrigerant temperature sensor 6 The case temperature is necessary because the main heat dissipation path from the stator core 31 and rotor 2 is the case 10. Because the refrigerant R accumulates in the drain, it comes into contact with a wide area of ​​the lower part of the case 10 where the drain is located, and due to thermal conduction, the case temperature is approximately equal to the refrigerant temperature. As a result, as shown in Figure 2, there is no need to calculate the thermal circuit network beyond the case 10, and no additional temperature sensor for the case 10 is required.

[0027] (3) Integration of the thermal circuit in rotor 2 When the temperature difference between the rotor core 21 and the rotor coil 22 in the rotor 2 is small, the components in the rotor 2 can be treated as one thermal mass, making it possible to omit temperature calculations of the thermal circuits in the rotor 2.

[0028] 3 is a diagram showing an example of a simplified thermal circuit network 11A according to this embodiment. As shown in FIG. 3, the simplified thermal circuit network 11A is a thermal circuit network that is simplified on the assumption that the stator coil end temperature is approximately equal to the stator coil temperature measured by the stator coil temperature sensor 7.

[0029] The temperature estimation device 9 uses the motor rotation speed, motor torque, stator coil temperature, refrigerant temperature, and refrigerant amount as inputs. Using the stator coil temperature and refrigerant temperature as boundary temperatures, the temperature estimation device 9 calculates the temperatures of the heat-generating parts of the stator slot coil 32C (see FIG. 1), stator core 31, rotor core 21, and rotor coil 22 from a simplified thermal circuit network 11A. This configuration enables highly accurate temperature prediction of the rotor coil 22.

[0030] 4 is a flowchart of a temperature prediction method using the simplified thermal network 11A according to this embodiment. Each process in the flowchart shown in FIG.

[0031] In step S1, the initial temperatures of the four heat generating portions, ie, the stator slot coil 32C, the stator core 31, the rotor core 21, and the rotor coil 22, are set.

[0032] Fig. 5 is a diagram illustrating an example of a method for estimating the initial temperature in step S1 of Fig. 4. The horizontal axis of Fig. 5 represents time (seconds), and the vertical axis represents temperature (°C).

[0033] If the transmission is soaked for a long time after driving, the temperature of each part in the transmission will converge to the outside air temperature, so after a certain amount of time has passed, the initial temperature of each part will be the refrigerant temperature or stator coil temperature when the ignition is turned on.

[0034] If the ignition was turned on immediately after the previous run, there is a possibility that the temperatures of each part have not converged to the refrigerant temperature and stator coil temperature. In this case, the initial temperature estimation shown in Figure 5 is performed. By storing the relationship between the temperature of each part and the temperature decrease over time as a function in advance, the initial temperature can be estimated from the temperature at the end of the previous run and the time elapsed from ignition off to ignition on. For example, the initial temperature estimation function shown in the bold line graph in Figure 5 can be used as the function used for this estimation.

[0035] Returning to FIG. 4, once the processing of step S1 is completed, the program proceeds to steps S2 and S3. In step S2, information on the motor torque and motor rotation speed is acquired. In step S3, the temperatures of each part at "n-Δt" seconds are acquired. As shown in FIG. 3, in this example, the measured value at time "n-Δt" seconds is acquired from the time-series data of temperature measured by the stator coil temperature sensor 7 as the temperature of the coil 32C in the stator slot. Furthermore, the measured value at time "n-Δt" seconds is acquired from the time-series data of temperature measured by the refrigerant temperature sensor 6 as the temperatures of the stator core 31, rotor core 21, and rotor coil 22. Once the processing of steps S2 and S3 is completed, the program proceeds to steps S4 and S5.

[0036] In step S4, the loss (heat generation amount) of each part is calculated. The heat generation amount can be calculated, for example, from a map of the heat generation amount of each part relative to the motor rotation speed and motor torque obtained in step S2. The loss of the stator slot coil 32C is, for example, stator coil copper loss and copper eddy current loss. The loss of the stator core 31 is, for example, stator iron loss. The loss of the rotor core 21 is, for example, rotor iron loss. The loss of the rotor coil 22 is, for example, rotor coil copper loss.

[0037] In step S5, the amount of heat dissipated and received by each part is calculated. The amount of heat dissipated and received can be calculated, for example, from the product of the temperature difference (°C) between adjacent parts and the thermal conductance (W / °C). After steps S4 and S5 are completed, the process proceeds to step S6.

[0038] In step S6, the temperature rise of each part during Δt seconds, i.e., the temperature rise ΔT, is calculated. The temperature rise ΔT can be calculated, for example, by the following equation (1) using the heat generation amount, heat radiation amount, and heat reception amount calculated in steps S4 and S5.

number

[0039] In step S7, the temperature T(n) of each part is calculated. The temperature T(n) can be calculated, for example, by the following formula (2) using the temperature rise ΔT calculated in step S6 and the temperature T(n-Δt) obtained in step S3 Δt seconds earlier.

number

[0040] When the processing of step S7 is completed, the process returns to steps S2 and S3. Furthermore, temperature estimation device 9 outputs information on the estimated temperature T(n) of each part calculated in step S7 to control device 8. Control device 8 can perform various controls of wound-field motor 1 using the information on the estimated temperature input from temperature estimation device 9. For example, when the estimated temperature T(n) of rotor winding 22 exceeds a predetermined threshold, control device 8 performs control to limit the motor load, thereby preventing insulation breakdown of rotor winding 22.

[0041] The simplified thermal network used for temperature estimation can also have a configuration other than that shown in Fig. 3. Three modified examples of the simplified thermal network will be described with reference to Figs.

[0042] Fig. 6 is a diagram showing a simplified thermal circuit network 11B according to the first modified example. As shown in Fig. 6, the simplified thermal circuit network 11B is a thermal circuit network that is a further simplification of the simplified thermal circuit network 11A in Fig. 3, assuming that when the temperature difference in the stator coil 32 is small, the coil temperature in the stator slot is approximately equal to the stator coil temperature measured by the stator coil temperature sensor 7.

[0043] The temperature estimation device 9 uses the motor rotation speed, motor torque, stator coil temperature, refrigerant temperature, and refrigerant amount as inputs, similar to the case where the simplified thermal network 11A of FIG. 3 is used. On the other hand, the temperature estimation device 9 calculates the temperatures of the stator core 31, rotor core 21, and rotor coil 22 from the simplified thermal network 11B, using the stator coil temperature and refrigerant temperature as boundary temperatures. This configuration also enables highly accurate temperature prediction of the rotor coil 22. Furthermore, the temperature of the rotor coil 22 can be predicted at a lower calculation cost than when the simplified thermal network 11A of FIG. 3 is used.

[0044] Even when the simplified thermal circuit network 11B of Fig. 6 is used, temperature prediction can be performed by applying the same processing as in the flowchart of Fig. 4. However, in this case, the various pieces of information calculated in each processing step of the flowchart shown in Fig. 4 are targeted at each of the three heat-generating parts: the stator core 31, the rotor core 21, and the rotor coil 22.

[0045] Fig. 7 is a diagram showing a simplified thermal network 11C according to a second modified example. As shown in Fig. 7, the simplified thermal network 11C is a thermal network further simplified from the simplified thermal network 11B in Fig. 6, on the assumption that when the temperature difference in the stator 3 is small, the temperature of the stator core 31 is approximately equal to the stator coil temperature measured by the stator coil temperature sensor 7.

[0046] The temperature estimation device 9 uses the motor rotation speed, motor torque, stator coil temperature, refrigerant temperature, and refrigerant amount as inputs, similarly to the simplified thermal network 11A of FIG. 3 and the simplified thermal network 11B of FIG. 6. Meanwhile, the temperature estimation device 9 calculates the temperatures of the rotor core 21 and rotor coil 22 from the simplified thermal network 11C, using the stator coil temperature and refrigerant temperature as boundary temperatures. This configuration also enables highly accurate temperature prediction of the rotor coil 22. Furthermore, the temperature of the rotor coil 22 can be predicted at a lower calculation cost than when using the simplified thermal network 11B of FIG. 6.

[0047] Even when the simplified thermal circuit network 11C of Fig. 7 is used, temperature prediction can be performed by applying the same processing as in the flowchart of Fig. 4. However, in this case, the various pieces of information calculated in each processing step of the flowchart shown in Fig. 4 are targeted at each part of the rotor core 21 and rotor coil 22, which are two heat-generating parts.

[0048] Fig. 8 is a diagram showing a simplified thermal network 11D according to a third modified example. As shown in Fig. 8, the simplified thermal network 11D is a thermal network that is a further simplification of the simplified thermal network 11C in Fig. 7, assuming that the temperature of the rotor core 21 is approximately equal to the temperature of the rotor coil 22 when the temperature difference within the rotor 2 is small. In the simplified thermal network 11D, the stator coil temperature measured by the stator coil temperature sensor 7 is assumed to be the temperature of the stator core 31.

[0049] The temperature estimation device 9 uses the motor rotation speed, motor torque, stator coil temperature, refrigerant temperature, and refrigerant amount as inputs, similar to the simplified thermal network 11A of FIG. 3, the simplified thermal network 11B of FIG. 6, and the simplified thermal network 11C of FIG. 7. Meanwhile, the temperature estimation device 9 calculates the temperature of the rotor coil 22 from the simplified thermal network 11D using the stator coil temperature and refrigerant temperature as boundary temperatures. This configuration also enables highly accurate temperature prediction of the rotor coil 22. Furthermore, the temperature of the rotor coil 22 can be predicted at a lower calculation cost than when using the simplified thermal network 11C of FIG. 7.

[0050] Even when the simplified thermal circuit network 11D of Fig. 8 is used, temperature prediction can be performed by applying the same processing as in the flowchart of Fig. 4. However, in this case, the target area for the various information calculated in each processing step of the flowchart shown in Fig. 4 is only the rotor coil 22, which is a single heat-generating area.

[0051] Summarizing the above-described embodiment and the first to third modifications, the temperature estimation device 9 of the wound-field motor 1 can be expressed as follows: it calculates the heat generation amount of the rotor winding 22 of the wound-field motor 1 based on temperature information measured by the stator coil temperature sensor 7 that measures the temperature of the stator coil 32 of the wound-field motor 1 and the refrigerant temperature sensor 6 that measures the temperature of the refrigerant R supplied to the wound-field motor 1, calculates the initial temperature of the rotor winding 22 based on the operating state since the end of the previous run, and estimates the temperature of the rotor winding 22 based on the heat generation amount and the initial temperature. With this configuration, it is possible to reduce estimation errors in the temperature of the rotor winding 22 of the wound-field motor 1.

[0052] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise. [Explanation of symbols]

[0053] Single-winding field motor 2 rotors 21 Rotor core 22 rotor coil 3 Stator 31 Stator core 32 stator coil 32A lead side coil end 32B Anti-lead coil end 32C stator slot coil 4 shafts 5 Cooling device 6 Refrigerant temperature sensor 7 Stator coil temperature sensor 8 Control Device 9 Temperature estimation device 10 cases 11 Thermal network 11A, 11B, 11C, 11D simplified heat circuit network R refrigerant

Claims

[Claim 1] A temperature estimation device for a wound field motor, comprising: calculating a heat generation amount of a rotor coil of the wound-field motor based on temperature information measured by a stator coil temperature sensor that measures the temperature of a stator coil of the wound-field motor and a refrigerant temperature sensor that measures the temperature of a refrigerant supplied to the wound-field motor; Calculating the initial temperature of the rotor coil based on the operating state since the end of the previous run; estimating a temperature of the rotor coil based on the heat generation amount and the initial temperature; Temperature estimation device for wound field motors.

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