Temperature estimation system

Abstract

To accurately estimate the temperature of a temperature estimation part of an MG directly connected to an engine.SOLUTION: A temperature estimation system (200) estimates the temperature of an MG (30) which is directly connected to an engine (20) and transmits driving force to the engine. The temperature estimation system includes a first temperature acquiring part (61) for acquiring the temperature of a direct coupling part (32) between an engine and an MG by detection or estimation when the MG generates power, a first estimating part (71) for estimating the temperature of the direct coupling part on the assumption that the MG is driven at the same rotation speed as during power generation and there is no heat transfer from the engine to the MG, a second temperature acquiring part (62) for detecting or estimating the temperature of a first predetermined place (35u) of the MG by detection or estimation, and a second estimating part (72) for estimating the temperature of a second predetermined place (35v) in the MG where the temperature is more likely to rise than the first predetermined place during power generation based on a temperature difference obtained by subtracting the temperature of the direct coupling part estimated from the acquired temperature of the direct coupling part and the acquired temperature of the first predetermined place.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a system for estimating the temperature of a motor generator (MG) directly connected to an engine. [Background technology]

[0002] For example, there is a temperature estimation system that estimates the maximum temperature of a multi-phase stator coil for a motor mounted on a hybrid vehicle that includes an engine and a motor as drive sources (see Patent Document 1). The temperature estimation system described in Patent Document 1 selects the maximum temperature of the multi-phase stator coil according to the rotational speed of the motor from a tentative maximum temperature of the multi-phase stator coil estimated using a detected value of the temperature of the coil conductor constituting the stator coil of a predetermined phase and an effective value based on multiple detected values ​​of the coil current flowing through the stator coil of a predetermined phase, and a tentative maximum temperature of the multi-phase stator coil estimated using a detected value of the temperature of the coil conductor and an instantaneous value of the coil current flowing through each of the stator coils of the multiple phases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-129967 Summary of the Invention [Problem to be solved by the invention]

[0004] The temperature estimation system described in Patent Document 1 takes into consideration that the appropriate model for estimating the maximum temperature of the stator coil changes depending on the rotation state of the motor, but does not consider heat transfer from the engine to the motor. In an MG directly connected to the engine, the amount of heat transferred from the engine to the MG is large. Therefore, the temperature estimation system described in Patent Document 1 cannot accurately estimate the temperature at the temperature estimation location of an MG directly connected to the engine.

[0005] The present invention has been made to solve the above-mentioned problems, and a main object of the present invention is to accurately estimate the temperature at a temperature estimation location of an MG directly connected to an engine. [Means for solving the problem]

[0006] The first means for solving the above problem is: A temperature estimation system (200) for estimating a temperature of an MG (30, 130) directly connected to an engine (20) and transmitting driving force to the engine, comprising: a first temperature acquisition unit (61, 61A) that acquires, by detection or estimation, a temperature of a direct connection portion (32) between the engine and the MG when the MG generates electricity using a driving force transmitted from the engine; a first estimation unit (71) that estimates the temperature of the directly coupled portion on the assumption that the MG is driven at the same rotational speed as during the power generation and that there is no heat transfer from the engine to the MG; a second temperature acquisition unit (62, 62A) that acquires the temperature of a first predetermined location (35u) of the MG by detecting or estimating the temperature; a second estimation unit (72) that estimates a temperature of a second predetermined location (35v) in the MG that is more likely to rise in temperature than the first predetermined location during the power generation, based on a temperature difference obtained by subtracting the temperature of the directly connected part estimated by the first estimation unit from the temperature of the directly connected part acquired by the first temperature acquisition unit and the temperature of the first predetermined location acquired by the second temperature acquisition unit; Equipped with.

[0007] According to the above configuration, the MG (Motor Generator) transmits driving force to the engine. Therefore, the MG can transmit driving force to the engine when in operation. Furthermore, the MG can generate electricity using the driving force transmitted from the engine. Because the MG is directly connected to the engine, the amount of heat transferred from the engine to the MG is greater than that of an MG that is not directly connected to the engine. When the MG is generating electricity, the engine generates the driving force required for generating electricity through combustion. Therefore, the amount of heat transferred from the engine to the MG when the MG is generating electricity is greater than the amount of heat transferred from the engine to the MG when the MG is in operation.

[0008] Here, the first temperature acquisition unit detects or estimates the temperature of the directly connected part between the engine and the MG when the MG is generating electricity. The first estimation unit estimates the temperature of the directly connected part assuming that the MG is rotating at the same rotational speed as when the MG is generating electricity and that there is no heat transfer from the engine to the MG. The temperature of the directly connected part estimated by the first estimation unit represents the temperature of the directly connected part excluding the temperature increase due to heat transfer from the engine to the MG when the MG is rotating in the same state as when the MG is generating electricity. Therefore, the temperature difference obtained by subtracting the temperature of the directly connected part estimated by the first estimation unit from the temperature of the directly connected part acquired by the first temperature acquisition unit represents the amount of temperature increase of the directly connected part due to heat transfer from the engine to the MG when the MG is generating electricity.

[0009] The second temperature acquisition unit acquires the temperature of a first predetermined location of the MG by detecting or estimating it. The first predetermined location is a location on the MG where the temperature can be directly detected or directly estimated. The second estimation unit estimates the temperature of a second predetermined location (corresponding to a temperature estimation location) on the MG where the temperature is more likely to rise than the first predetermined location during power generation, based on the temperature difference and the temperature of the first predetermined location acquired by the second temperature acquisition unit. This makes it possible to estimate the temperature of the second predetermined location by reflecting the amount of temperature rise due to heat transfer from the engine to the MG during power generation. Therefore, even if the second predetermined location is a location on the MG directly connected to the engine where the temperature cannot be directly detected or directly estimated, the temperature of the second predetermined location can be accurately estimated. [Brief explanation of the drawings]

[0010] [Figure 1] Block diagram of the engine, MG, and temperature estimation system. [Figure 2] FIG. 2 is a cross-sectional view showing an example of a direct connection structure between an engine and an MG. [Figure 3] 10 is a flowchart showing a procedure for estimating the temperature of the hottest part. [Figure 4] A map used to estimate the temperature of direct connections. [Figure 5] 4 is a time chart showing the temperatures of various parts when the power generation output is limited. [Figure 6] 4 is a time chart showing the temperatures of various parts when power generation output is not limited. [Figure 7] 10 is a flowchart showing a modified example of the procedure for estimating the temperature of the hottest part. [Figure 8] FIG. 10 is a block diagram of a modified example of the engine, MG, and temperature estimation system. [Figure 9] FIG. 10 is a cross-sectional view showing a modified example of the direct connection structure between the engine and the MG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of a temperature estimation system for estimating the temperature of an MG of a power generation system including an engine and an MG will be described with reference to the drawings.

[0012] As shown in FIG. 1, the power generation system 100 includes an engine 20, an MG 30, an inverter 40, a heat exchanger 51, a water pump 52, and the like.

[0013] The engine 20 generates driving force by burning fuel. The engine 20 may be a gasoline engine that uses gasoline as fuel, a diesel engine that uses diesel as fuel, or the like. The engine 20 is not limited to a reciprocating engine, and may also be a rotary engine.

[0014] The MG 30 functions as a motor that generates driving force when driven and as a generator that generates electric power when generated. The MG 30 is, for example, a three-phase permanent magnet motor generator.

[0015] The inverter 40 converts DC power from a battery (not shown) into AC power and supplies it to the MG 30. The inverter 40 is a three-phase inverter configured with, for example, six switching elements and six anti-parallel diodes.

[0016] The MG 30 and the inverter 40 are cooled by cooling water circulated by a cooling mechanism. The cooling mechanism includes a heat exchanger 51, a water pump 52, a cooling water inlet 55, a cooling water outlet 56, and a cooling water passage 57 connecting these. The water pump 52 circulates the cooling water through the cooling water passage 57 by drawing in and discharging the cooling water. The heat exchanger 51 exchanges heat between the cooling water and the atmosphere, for example. The cooling water inlet 55 is an inlet for the cooling water to the MG 30. The cooling water outlet 56 is an outlet for the cooling water from the MG 30.

[0017] The engine 20 and the MG 30 are directly connected (i.e., directly coupled). In other words, the engine 20 and the MG 30 are joined to each other without any space between them. An example of a direct connection structure between the engine 20 and the MG 30 will be described with reference to Fig. 2. Here, the case where the engine 20 is a reciprocating engine will be described.

[0018] The engine 20 includes a cylinder block 21, an oil pan 22, and a crankshaft 23. The cylinder block 21 (corresponding to a housing) and the oil pan 22 (corresponding to a housing) are joined together by bolts (not shown) or the like. A piston (not shown) is slidably housed in the cylinder block 21. The reciprocating motion of the piston accompanying the combustion of fuel causes the crankshaft 23 (corresponding to an output shaft) to rotate.

[0019] A flange 23a and an engaging portion 23b are provided at the tip of the crankshaft 23. The flange 23a is formed in a disk shape. The engaging portion 23b is formed in a cylindrical shape and extends from the flange 23a in the axial direction of the crankshaft 23.

[0020] The MG 30 includes a first housing 31, a second housing 32, a holding component 33, a core 34, coils 35 (including a U-phase 35u, a V-phase 35v, and a W-phase 35w), a rotor carrier 36, a magnet 37, a cover 38, and the like.

[0021] The first housing 31 is formed in a cylindrical shape with a bottom. A through hole 31b is formed in the center of the bottom 31a of the first housing 31. The through hole 31b is formed on the bottom 31a on an extension of the axis of the crankshaft 23, and faces the flange 23a and engaging portion 23b of the crankshaft 23. A cover 38 can be attached and detached to a position on the bottom 31a corresponding to the through hole 31b. When attached to the bottom 31a, the cover 38 closes the through hole 31b and seals the first housing 31.

[0022] A core 34 is attached (fixed) to the outer periphery of the through hole 31b in the bottom portion 31a. The core 34 extends cylindrically from the bottom portion 31a in the axial direction of the crankshaft 23. The core 34 is formed, for example, by laminating a plurality of metal plates. A coil 35 is formed by winding a wire around an electrode portion formed on the core 34. A portion of the coil 35 is disposed on the outer periphery of the core 34. The core 34 and the coil 35 form a stator.

[0023] The second housing 32 is formed in a disk shape. A through hole 32c is formed in the center of the second housing 32. A fixed portion 32a that is fixed to a predetermined portion 21a of the cylinder block 21 and a fixed portion 32b that is fixed to a predetermined portion 22a of the oil pan 22 are provided on the outer edge of the second housing 32. The fixed portion 32a is formed in a shape that corresponds to the shape of the predetermined portion 21a of the cylinder block 21. The fixed portion 32b is formed in a shape that corresponds to the shape of the predetermined portion 22a of the oil pan 22. A holding component 33 is attached to the inner peripheral edge of the second housing 32 (the inner peripheral surface of the through hole 32c). The holding component 33 is formed in an annular shape.

[0024] The first housing 31 and the second housing 32 are connected by bolts (corresponding to fastening members) not shown. In other words, the second housing 32 is attached to the first housing 31. A fixed portion 32a of the second housing 32 and a predetermined portion 21a of the cylinder block 21 are connected by bolts not shown. A fixed portion 32b of the second housing 32 and a predetermined portion 22a of the oil pan 22 are connected by bolts not shown. In other words, the second housing 32 is fixed to the cylinder block 21 and the oil pan 22 (and thus the engine 20). As a result, the first housing 31, and therefore the core 34, the coil 35, and the cover 38, are fixed to the cylinder block 21 and the oil pan 22 via the second housing 32. With this structure, the engine 20 and the MG 30 are directly connected. The second housing 32 corresponds to the directly connected portion.

[0025] The rotor carrier 36 is formed in a cylindrical shape with a bottom. A connecting portion 36b is provided at the center of a bottom portion 36a of the rotor carrier 36. The connecting portion 36b extends cylindrically from the bottom portion 36a in the axial direction of the crankshaft 23. The connecting portion 36b is fitted onto the outer periphery of the engagement portion 23b. The flange 23a (and thus the crankshaft 23) and the connecting portion 36b (and thus the rotor carrier 36) are connected (i.e., directly connected) by bolts (not shown). Therefore, the rotation speed of the crankshaft 23 and the rotation speed of the rotor carrier 36 are equal. The rotor carrier 36 and the magnet 37 form a rotor (corresponding to a rotor).

[0026] Magnets 37 are arranged on the inner periphery of the rotor carrier 36. The rotor is arranged outside the stator, and the MG 30 has a so-called outer rotor structure.

[0027] When power is supplied to the MG 30 during operation, the MG 30 generates a driving force to rotate the crankshaft 23. When power is generated, the MG 30 generates power by rotating the rotor carrier 36 and the magnet 37 due to the driving force of the crankshaft 23.

[0028] 1, the temperature estimation system 200 includes a direct connection part temperature sensor 61, a coil temperature sensor 62, a coolant temperature sensor 63, an ambient air temperature sensor 64, an MG rotation speed sensor 65, an MG torque estimation unit 66, and an ECU (Electronic Control Unit) 70. The direct connection part temperature sensor 61, the coil temperature sensor 62, the coolant temperature sensor 63, and the ambient air temperature sensor 64 are configured by, for example, a thermistor or a thermocouple.

[0029] The direct connection temperature sensor 61 (corresponding to the first temperature acquisition unit) detects the temperature Tjg of the second housing 32 (see FIG. 2). More specifically, the direct connection temperature sensor 61 detects the temperature Tjg of the joint surface between the predetermined portion 21a of the cylinder block 21 and the fixed portion 32a of the second housing 32. The coil temperature sensor 62 (corresponding to the second temperature acquisition unit) detects the temperature Tc of, for example, the U-phase 35u (corresponding to the first predetermined location) of the coil 35 of the MG 30. The coolant temperature sensor 63 (corresponding to the coolant temperature acquisition unit) detects the temperature Tw of the coolant flowing into the coolant inlet 55. The ambient air temperature sensor 64 (corresponding to the air temperature acquisition unit) detects the temperature Ta of the air surrounding the MG 30.

[0030] An MG rotational speed sensor 65 (corresponding to a rotational speed acquisition unit) detects the rotational speed N of the rotor carrier 36 (i.e., the MG 30). An MG torque estimation unit 66 (equivalent to a torque estimation unit) estimates the torque Tq that should be generated by the MG 30 in order to maintain the rotational speed N of the MG 30 detected by the MG rotational speed sensor 65 (i.e., the rotational speed N of the engine 20) when it is assumed that the MG 30 is being driven.

[0031] The ECU 70 is mainly configured with a microcomputer including a CPU, memory (ROM, RAM), an input / output interface, etc. Detection results from the direct connection part temperature sensor 61, the coil temperature sensor 62, the coolant temperature sensor 63, the ambient air temperature sensor 64, and the MG rotation speed sensor 65, as well as the estimation result from the MG torque estimation unit 66, are input to the ECU 70. The ECU 70 executes programs stored in the memory to realize the functions of a first estimation unit 71 and a second estimation unit 72. The first estimation unit 71 and the second estimation unit 72 will be described in detail later.

[0032] Incidentally, since the MG 30 is directly connected to the engine 20, a greater amount of heat is transferred from the engine 20 to the MG 30 compared to an MG that is not directly connected to the engine 20. When the MG 30 generates electricity, the engine 20 generates torque (driving force) required for power generation by burning fuel. Specifically, when the MG 30 generates electricity, the engine 20 rotates the rotor carrier 36 and the magnet 37 using the torque generated by burning fuel, causing the coil 35 to generate power. At this time, heat is transferred from the cylinder block 21 to the core 34 and the coil 35 via the second housing 32 and the first housing 31. The generated power in the coil 35 is supplied to a load (not shown) or the like.

[0033] On the other hand, even when the MG 30 is not generating power, the engine 20 continues to burn fuel. For example, the engine 20 may be idling or may be rotating at a constant low rotation speed. At this time, the MG 30 is driving and generates torque to stabilize the rotation speed of the engine 20 (and thus the combustion of fuel) and to maintain the rotation speed of the engine 20 at a constant low rotation speed. When the MG 30 is driving, the torque generated by the engine 20 is small, and therefore the amount of heat generated by the combustion of fuel in the engine 20 is small. Therefore, the amount of heat transferred from the engine 20 to the MG 30 when the MG 30 is generating power is greater than the amount of heat transferred from the engine 20 to the MG 30 when the MG 30 is driving. Therefore, the temperature of the MG 30 when generating power is likely to be higher than the temperature of the MG 30 when driving.

[0034] In some cases, the temperature Tt of the coil 35, for example, the V-phase 35v (corresponding to the second predetermined location), which is the part of the coil 35 that is hottest during power generation of the MG 30, cannot be detected by a temperature sensor. Specifically, depending on the structure and arrangement of the core 34 and the coil 35, it may not be possible to attach a temperature sensor to detect the temperature of the V-phase 35v. The phase of the coil 35 that is hottest during power generation is determined by its position relative to other components of the MG 30, its position relative to the cooling water flow path within the MG 30, its position relative to the engine 20, and other factors. The location of the hottest part of the MG 30 that is hottest during power generation (e.g., a specific part of the V-phase 35v) can be known in advance based on the design and testing of the power generation system 100. For example, the V-phase 35v is a part of the MG 30 that is more likely to rise in temperature than the U-phase 35u during power generation. To prevent damage to the MG 30 due to heat during high-power power generation, it is desirable to accurately estimate the temperature Tt of the hottest part of the MG 30.

[0035] 3 is a flowchart showing the procedure for estimating the temperature of the hottest part. This series of processes is repeatedly executed by the ECU 70 at a predetermined interval when the MG 30 is generating electricity.

[0036] First, the temperature Tjg of the direct connection part when the MG 30 is generating electricity is detected (S10). Specifically, the temperature Tjg of the second housing 32 is detected by the direct connection part temperature sensor 61.

[0037] Next, the temperature Tjd of the directly connected portion is estimated assuming that the MG 30 is operating and there is no heat transfer from the engine 20 to the MG 30 (S11). Specifically, the temperature Tjd of the directly connected portion is estimated as follows: The coolant temperature sensor 63 detects the temperature Tw of the coolant flowing into the coolant inlet 55, the ambient air temperature sensor 64 detects the temperature Ta of the air surrounding the MG 30, the MG rotational speed sensor 65 detects the rotational speed N of the MG 30, and the MG torque estimator 66 estimates the torque Tq to be generated by the MG 30. As shown in FIG. 4, the first estimator 71 has a map that defines the relationships between the rotational speed N of the MG 30, the torque Tq to be generated by the MG 30, the temperature Tw of the coolant, the temperature Ta of the air, and the temperature Tjd of the second housing 32 when there is no heat transfer from the engine 20 to the MG 30 while the MG 30 is operating (when it is assumed that there is no heat transfer). In the map, the higher the density of dots, the higher the temperature Tjd of the second housing 32. This map can be obtained in advance based on testing or the like. The first estimator 71 estimates the temperature Tjd of the second housing 32 by applying the rotation speed N detected by the MG rotation speed sensor 65, the torque Tq estimated by the MG torque estimator, the coolant temperature Tw detected by the coolant temperature sensor 63, and the atmospheric temperature Ta detected by the ambient air temperature sensor 64 to this map. That is, the first estimator 71 estimates the temperature Tjd of the second housing 32 by taking into account the coolant temperature Tw detected by the coolant temperature sensor 63 and the atmospheric temperature Ta detected by the ambient air temperature sensor 64. Note that FIG. 4 shows three maps specifying the relationship between the rotation speed N of the MG 30, the torque Tq of the MG 30, and the temperature Tjd of the second housing 32. However, the portions between these maps may be interpolated based on the atmospheric temperature Ta and the coolant temperature Tw. The maps may also be updated by learning the effects of the atmospheric temperature Ta and the coolant temperature Tw.

[0038] Next, it is determined whether the temperature difference ΔTj, which is the temperature Tjg of the second housing 32 detected by the direct-coupled portion temperature sensor 61 minus the temperature Tjd of the second housing 32 estimated by the first estimator 71, is smaller than a threshold value Tth (S12). The threshold value Tth is set to a value that allows determination of whether the influence of heat transfer from the engine 20 to the MG 30 is small when the MG 30 is generating electricity. If it is determined that the temperature difference ΔTj is smaller than the threshold value Tth (S12: YES), it is estimated that the temperature Tt of the hottest portion of the MG 30 is equal to the temperature of a predetermined coil (S13). The hottest portion of the MG 30 is, for example, a specific portion of the V-phase 35v. The temperature Tc of the predetermined coil is, for example, the temperature Tc of the U-phase 35u detected by the coil temperature sensor 62. Then, this series of processes is temporarily terminated (END).

[0039] On the other hand, if it is determined in step S12 that the temperature difference ΔTj is not smaller than the threshold value Tth (S12: NO), the temperature rise Tu of the temperature Tt of the hottest part relative to the temperature Tc of the specified coil is calculated by multiplying the temperature difference ΔTj by a predetermined coefficient a (S14). That is, the temperature rise Tu is calculated using the formula Tu = ΔTj × a. The predetermined coefficient a, which defines the relationship between the temperature difference ΔTj and the temperature rise Tu of the temperature Tt of the hottest part relative to the temperature Tc of the specified coil, can be obtained in advance based on testing or the like.

[0040] Next, the temperature Tt of the hottest part is calculated by adding the temperature rise Tu to the temperature Tc of the specified coil (S15). For example, the calculated temperature rise Tu is added to the temperature Tc of the U phase 35u detected by the direct-coupled part temperature sensor 61 to calculate the temperature Tt of the specified part of the V phase 35v (Tt = Tc + Tu). Then, this series of processes is temporarily ended (END).

[0041] The process of S10 corresponds to the process performed by the first temperature acquisition unit, the process of S11 corresponds to the process performed by the first estimation unit 71, and the processes of S12 to S15 correspond to the process performed by the second estimation unit 72.

[0042] If the temperature Tt of the hottest part estimated by the ECU 70 exceeds an upper limit temperature Tlim, the power generation output of the MG 30 is limited. The upper limit temperature Tlim is set to a temperature as high as possible within a range that can prevent damage to the MG 30 due to heat generated during high-power power generation. Note that if the temperature Tt of the hottest part estimated by the ECU 70 exceeds the upper limit temperature Tlim, the power generation of the MG 30 may be stopped.

[0043] FIG. 5 is a time chart showing the temperature of each component and the power generation output when the power generation output is limited. At timing t11, the MG 30 starts generating power using the driving force of the engine 20. From timing t11 to t12, the temperature difference ΔTj, which is calculated by subtracting the estimated temperature Tjd of the second housing 32 from the detected temperature Tjg of the second housing 32, is smaller than the threshold value Tth. Therefore, the temperature Tt of the V-phase 35v (highest temperature part) is estimated to be equal to the temperature Tc of the U-phase 35u (predetermined coil). After timing t12, the temperature difference ΔTj becomes greater than the threshold value Tth. Therefore, the temperature Tt of the V-phase 35v is calculated by adding the detected temperature Tc of the U-phase 35u to the temperature increase Tu, which is calculated by multiplying the temperature difference ΔTj by a predetermined coefficient a (Tt = Tc + ΔTj × a). At timing t13, the temperature Tt of the V-phase 35v becomes higher than the upper limit temperature Tlim, and the power generation output of the MG 30 is limited. After that, the temperature Tt of the V-phase 35v drops.

[0044] FIG. 6 is a time chart showing the temperatures of various components when the power generation output is not limited. At timing t21, the MG 30 starts generating power using the driving force of the engine 20. From timing t21 to t22, the temperature difference ΔTj is smaller than the threshold value Tth. Therefore, the temperature Tt of the V-phase 35v (highest temperature part) is estimated to be equal to the temperature Tc of the U-phase 35u (predetermined coil). After timing t22, the temperature difference ΔTj becomes greater than the threshold value Tth. Therefore, the temperature Tt of the V-phase 35v is calculated by adding the detected temperature Tc of the U-phase 35u to the temperature rise Tu, which is calculated by multiplying the temperature difference ΔTj by a predetermined coefficient a (Tt = Tc + ΔTj × a). After timing t22, the temperature Tt of the V-phase 35v remains lower than the upper limit temperature Tlim, so the power generation output of the MG 30 is not limited.

[0045] The present embodiment described above in detail has the following advantages.

[0046] The direct-coupled portion temperature sensor 61 detects the temperature Tjg of the direct-coupled portion (specifically, the second housing 32) between the engine 20 and the MG 30 when the MG 30 is generating electricity. The first estimator 71 estimates the temperature Tjd of the second housing 32 when it is assumed that the MG 30 is rotating at the same rotation speed N as when the MG 30 is generating electricity and that there is no heat transfer from the engine 20 to the MG 30. The temperature Tjd of the second housing 32 estimated by the first estimator 71 represents the temperature of the second housing 32 excluding the temperature increase due to heat transfer from the engine 20 to the MG 30 when the MG 30 is rotating in the same rotational state as when the MG 30 is generating electricity. Therefore, the temperature difference ΔTj obtained by subtracting the temperature Tjd of the second housing 32 estimated by the first estimator 71 from the temperature Tjg of the second housing 32 detected by the direct-coupled portion temperature sensor 61 represents the amount of temperature increase in the second housing 32 due to heat transfer from the engine 20 to the MG 30 when the MG 30 is generating electricity.

[0047] The coil temperature sensor 62 detects the temperature Tc of the U-phase 35u (corresponding to a first predetermined location) of the coil 35 of the MG 30. The U-phase 35u is a location in the MG 30 whose temperature can be directly detected. The second estimation unit 72 estimates the temperature Tt of the V-phase 35v (corresponding to a second predetermined location), whose temperature is more likely to rise than the U-phase 35u during power generation in the MG 30, based on the temperature difference ΔTj obtained by subtracting the temperature Tjd of the second housing 32 estimated by the first estimation unit 71 from the temperature Tjg of the second housing 32 detected by the direct-connection temperature sensor 61, and the temperature Tc of the U-phase 35u detected by the coil temperature sensor 62. This allows the temperature Tt of the V-phase 35v to be estimated by reflecting the amount of temperature rise due to heat transfer from the engine 20 to the MG 30 during power generation in the MG 30. Therefore, even though the V-phase 35v is a location in the MG 30 whose temperature cannot be directly detected in the MG 30, the temperature Tt of the V-phase 35v can be accurately estimated in the MG 30, which is directly connected to the engine 20.

[0048] The second estimation unit 72 estimates the temperature Tt of the V-phase 35v by adding the temperature rise Tu calculated by multiplying the temperature difference ΔTj by a predetermined coefficient a obtained in advance to the temperature Tc of the U-phase 35u detected by the coil temperature sensor 62. Here, the predetermined coefficient a that defines the relationship between the temperature difference ΔTj and the temperature rise Tu of the V-phase 35v can be obtained in advance based on testing or the like. Therefore, the temperature Tt of the V-phase 35v can be accurately estimated by a simple calculation.

[0049] When the temperature difference ΔTj is smaller than the threshold value Tth, the second estimation unit 72 estimates that the temperature Tt of the V-phase 35v is equal to the temperature Tc of the U-phase 35u detected by the coil temperature sensor 62. Therefore, when the temperature difference ΔTj is smaller than the threshold value Tth and the influence of heat transfer from the engine 20 to the MG 30 when the MG 30 is generating electricity is small, it is possible to simply estimate that the temperature Tt of the V-phase 35v is equal to the temperature Tc of the U-phase 35u. On the other hand, when the temperature difference ΔTj is larger than the threshold value Tth and the influence of heat transfer from the engine 20 to the MG 30 when the MG 30 is generating electricity is large, it is possible to accurately estimate the temperature Tt of the V-phase 35v based on the temperature difference ΔTj and the temperature Tc of the U-phase 35u.

[0050] The first estimation unit 71 estimates the temperature Tjd of the second housing 32 by taking into account the coolant temperature Tw detected by the coolant temperature sensor 63 and the atmospheric temperature Ta detected by the ambient atmospheric temperature sensor 64. This makes it possible to accurately estimate the temperature Tjd of the second housing 32 by reflecting the influence of the cooling mechanism that cools the MG 30 with coolant on the temperature Tjd of the second housing 32 and the influence of the atmosphere surrounding the MG 30 on the temperature Tjd of the second housing 32.

[0051] The first estimation unit 71 estimates the temperature Tjd of the second housing 32 by applying to a map the rotation speed N detected by the MG rotation speed sensor 65, the torque Tq estimated by the MG torque estimation unit 66, the coolant temperature Tw detected by the coolant temperature sensor 63, and the atmospheric temperature Ta detected by the ambient air temperature sensor 64. This reduces the calculation load on the first estimator 71 when estimating the temperature Tjd of the second housing 32.

[0052] The above embodiment can be modified as follows: The same parts as those in the above embodiment are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0053] The ECU 70 may omit the processes of S12 and S13 in Fig. 3 and always execute the processes of S14 and S15 after the process of S11 as shown in Fig. 7. In Fig. 7, the same processes as in Fig. 3 are designated by the same step numbers S, and the explanation thereof is incorporated herein. Even in this case, in the MG 30 directly connected to the engine 20, the temperature Tt of the V-phase 35v can be accurately estimated even if the temperature of the V-phase 35v is not directly detectable by the MG 30.

[0054] 1, the temperature estimation system 200 may include a direct-coupled portion temperature estimator 61A (corresponding to the first temperature acquisition unit) as shown in FIG. 8, which estimates the temperature Tjd of the second housing 32 based on any one of the estimated torque of the engine 20, the exhaust temperature of the engine 20, and the coolant temperature of the engine 20. This configuration allows the temperature Tjd of the second housing 32 to be estimated even when the direct-coupled portion temperature sensor 61 for detecting the temperature Tjd of the second housing 32 cannot be installed. Furthermore, the temperature estimation system 200 may include the direct-coupled portion temperature estimator 61A in addition to the direct-coupled portion temperature sensor 61 of FIG. 1. This configuration allows the temperature Tjd of the second housing 32 to be estimated even when the direct-coupled portion temperature sensor 61 for detecting the temperature Tjd of the second housing 32 fails. Therefore, even in these cases, the temperature Tt of the V-phase 35v can be accurately estimated by reflecting the temperature increase Tu due to heat transfer from the engine 20 to the MG 30 when the MG 30 is generating electricity.

[0055] 1, the temperature estimation system 200 may include a coil temperature estimator 62A (corresponding to a second temperature acquisition unit) that estimates the temperature Tc of the U phase 35u (corresponding to a first predetermined location) based on the power generation output of the MG 30, as shown in FIG. 8. With this configuration, even if the coil temperature sensor 62 that detects the temperature Tc of the U phase 35u cannot be installed, the temperature Tc of the U phase 35u can be estimated. Furthermore, the temperature estimation system 200 may include the coil temperature estimator 62A in addition to the coil temperature sensor 62 of FIG. 1. With this configuration, even if the coil temperature sensor 62 that detects the temperature Tc of the U phase 35u fails, the temperature Tc of the U phase 35u can be estimated.

[0056] 1, or in addition to the coolant temperature sensor 63, the temperature estimation system 200 may include a coolant temperature estimation unit 63A (corresponding to the coolant temperature acquisition unit) that estimates the temperature Tw of the coolant flowing into the coolant inlet 55, as shown in Fig. 8. Also, instead of the ambient air temperature sensor 64 of Fig. 1, or in addition to the ambient air temperature sensor 64, the temperature estimation system 200 may include an ambient air temperature estimation unit 64A (corresponding to the ambient temperature acquisition unit) that estimates the temperature Ta of the air surrounding the MG 30, as shown in Fig. 8. Also, instead of the MG rotation speed sensor 65 of Fig. 1, or in addition to the MG rotation speed sensor 65, the temperature estimation system 200 may include an MG rotation speed estimation unit 65A (corresponding to the rotation speed acquisition unit) that estimates the rotation speed N of the MG 30, as shown in Fig. 8.

[0057] Of the parameters used to estimate the temperature Tjd of the directly connected portion when the MG 30 is operating and there is no heat transfer from the engine 20 to the MG 30, at least one of the coolant temperature Tw, the air temperature Ta around the MG 30, the rotation speed N of the MG 30, and the torque Tq to be generated by the MG 30 may be omitted. In this case, the map shown in FIG. 4 may be changed according to the omitted parameter.

[0058] A map specifying the relationship between the temperature Tc of the U phase 35u (corresponding to the first predetermined location), the temperature difference ΔTj, and the temperature Tt of the V phase 35v (corresponding to the second predetermined location) is obtained in advance based on testing or the like, and the second estimation unit 72 can estimate the temperature Tt of the V phase 35v by applying the temperature Tc and temperature difference ΔTj of the U phase 35u to this map.

[0059] The temperature estimation system 200 may include a plurality of second temperature acquisition units that detect or estimate the temperature of the first predetermined location. In this case, when estimating the temperature of the second predetermined location, the ECU 70 may use the temperature of the first predetermined location acquired by any one of the plurality of second temperature acquisition units, or may use a temperature obtained by averaging the temperatures of the plurality of first predetermined locations acquired by the plurality of second temperature acquisition units. The ECU 70 then calculates the temperature rise Tu using a predetermined coefficient a that corresponds to the temperature of the first predetermined location used.

[0060] The first predetermined location where the temperature is detected or estimated in the MG 30 is not limited to a predetermined phase of the coil 35, but may be a predetermined part of the core 34. However, to accurately estimate the temperature of the second predetermined location, it is preferable that the location be close to the second predetermined location.

[0061] The hottest part of the MG 30 (corresponding to the second predetermined location and the temperature estimation location) is not limited to a specific part of the coil 35, but may be a specific part of the core 34. In other words, the second predetermined location from which the second estimation unit 72 estimates the temperature may be any location where the temperature is more likely to rise than the first predetermined location from which the temperature is detected or estimated.

[0062] As shown in Figure 9, an MG 130 with an inner rotor structure can also be used. The core 34 and coil 35 (stator) are attached (fixed) to the first housing 31. In this case, heat is also transferred from the cylinder block 21 to the core 34 and coil 35 via the second housing 32 and the first housing 31. Even in this configuration, the temperature estimation process for the hottest part shown in the flowcharts of Figures 3 and 7 can be applied.

[0063] The MG 30 is not limited to a permanent magnet type MG, but may be a field winding type MG.

[0064] The power generation system 100 to which the temperature estimation system 200 is applied may be a stationary power generation system or a power generation system mounted on a range extender EV. In a range extender EV, the driving force of the engine 20 is not used to drive the EV, but is used to generate electricity using the MG 30.

[0065] The above-described embodiment and modifications may be combined within the scope of possible combinations.

[0066] Characteristic configurations extracted from the above-described embodiments and modifications will be described below. [Configuration 1] A temperature estimation system (200) for estimating a temperature of an MG (30, 130) directly connected to an engine (20) and transmitting driving force to the engine, comprising: a first temperature acquisition unit (61, 61A) that acquires, by detection or estimation, a temperature of a direct connection portion (32) between the engine and the MG when the MG generates electricity using a driving force transmitted from the engine; a first estimation unit (71) that estimates the temperature of the directly coupled portion on the assumption that the MG is driven at the same rotational speed as during the power generation and that there is no heat transfer from the engine to the MG; a second temperature acquisition unit (62, 62A) that acquires the temperature of a first predetermined location (35u) of the MG by detecting or estimating the temperature; a second estimation unit (72) that estimates a temperature of a second predetermined location (35v) in the MG that is more likely to rise in temperature than the first predetermined location during the power generation, based on a temperature difference obtained by subtracting the temperature of the directly connected part estimated by the first estimation unit from the temperature of the directly connected part acquired by the first temperature acquisition unit and the temperature of the first predetermined location acquired by the second temperature acquisition unit; A temperature estimation system comprising: [Configuration 2] The temperature estimation system according to configuration 1, wherein the second estimation unit estimates the temperature of the second predetermined location by adding a temperature increase amount calculated by multiplying the temperature difference by a predetermined coefficient acquired in advance to the temperature of the first predetermined location acquired by the second temperature acquisition unit. [Configuration 3] The temperature estimation system of configuration 1 or 2, wherein the second estimation unit estimates that the temperature of the second predetermined location is equal to the temperature of the first predetermined location acquired by the second temperature acquisition unit when the temperature difference is smaller than a threshold value, and estimates the temperature of the second predetermined location based on the temperature difference and the temperature of the first predetermined location acquired by the second temperature acquisition unit when the temperature difference is not smaller than the threshold value. [Configuration 4] a cooling mechanism (51, 52, 55, 56, 57) that cools the MG with cooling water; a coolant temperature acquisition unit (63, 63A) that acquires the temperature of the coolant by detecting or estimating the temperature; an atmospheric temperature acquisition unit (64, 64A) that acquires the temperature of the atmosphere around the MG by detecting or estimating it; Equipped with The temperature estimation system according to any one of configurations 1 to 3, wherein the first estimation unit estimates the temperature of the directly connected part by taking into account the temperature of the cooling water acquired by the cooling water temperature acquisition unit and the temperature of the atmosphere acquired by the atmosphere temperature acquisition unit. [Configuration 5] a rotation speed acquisition unit (65, 65A) that acquires the rotation speed of the MG by detecting or estimating; a torque estimation unit (66) that estimates the torque of the MG; Equipped with The temperature estimation system of configuration 4, wherein the first estimation unit has a map that defines the relationship between the rotational speed of the MG, the torque of the MG, the temperature of the cooling water, the temperature of the atmosphere, and the temperature of the directly connected part, and estimates the temperature of the directly connected part by applying the rotational speed acquired by the rotational speed acquisition unit, the torque estimated by the torque estimation unit, the temperature of the cooling water acquired by the cooling water temperature acquisition unit, and the temperature of the atmosphere acquired by the atmosphere temperature acquisition unit to the map. [Configuration 6] The temperature estimation system according to any one of configurations 1 to 6, wherein the first temperature acquisition unit (61A) acquires the temperature of the directly connected part by estimation based on any one of an estimated torque of the engine, an exhaust temperature of the engine, and a coolant temperature of the engine. [Explanation of symbols]

[0067] 20...engine, 30...MG, 34...core, 35...coil, 35u...U phase, 35v...V phase, 61...direct connection part temperature sensor, 61A...direct connection part temperature estimation part, 62...coil temperature sensor, 62A...coil temperature estimation part, 70...ECU, 71...first estimation part, 72...second estimation part, 100...power generation system, 200...temperature estimation system.

Claims

1. A temperature estimation system (200) that estimates the temperature of an MG (30, 130) that is directly connected to an engine (20) and transmits driving force to the engine, comprising: a first temperature acquisition unit (61, 61A) that acquires, by detection or estimation, a temperature of a direct connection portion (32) between the engine and the MG when the MG generates electricity using a driving force transmitted from the engine; a first estimation unit (71) that estimates the temperature of the directly coupled portion on the assumption that the MG is driven at the same rotational speed as during the power generation and that there is no heat transfer from the engine to the MG; a second temperature acquisition unit (62, 62A) that acquires the temperature of a first predetermined location (35u) of the MG by detecting or estimating the temperature; a second estimation unit (72) that estimates the temperature of a second predetermined location (35v) in the MG, the temperature of which is more likely to rise than the first predetermined location during the power generation, based on a temperature difference obtained by subtracting the temperature of the directly connected part estimated by the first estimation unit from the temperature of the directly connected part acquired by the first temperature acquisition unit and the temperature of the first predetermined location acquired by the second temperature acquisition unit; A temperature estimation system comprising:

2. 2. The temperature estimation system of claim 1, wherein the second estimation unit estimates the temperature of the second predetermined location by adding the temperature increase calculated by multiplying the temperature difference by a predetermined coefficient acquired in advance to the temperature of the first predetermined location acquired by the second temperature acquisition unit.

3. 3. The temperature estimation system of claim 1, wherein the second estimation unit estimates that the temperature of the second specified location is equal to the temperature of the first specified location acquired by the second temperature acquisition unit when the temperature difference is smaller than a threshold value, and estimates the temperature of the second specified location based on the temperature difference and the temperature of the first specified location acquired by the second temperature acquisition unit when the temperature difference is not smaller than the threshold value.

4. a cooling mechanism (51, 52, 55, 56, 57) that cools the MG with cooling water; a coolant temperature acquisition unit (63, 63A) that acquires the temperature of the coolant by detecting or estimating the temperature; an atmospheric temperature acquisition unit (64, 64A) that acquires the temperature of the atmosphere around the MG by detecting or estimating; Equipped with 3. The temperature estimation system according to claim 1, wherein the first estimation unit estimates the temperature of the directly connected part by taking into account the temperature of the coolant acquired by the coolant temperature acquisition unit and the temperature of the atmosphere acquired by the atmosphere temperature acquisition unit.

5. a rotation speed acquisition unit (65, 65A) that acquires the rotation speed of the MG by detecting or estimating; a torque estimation unit (66) that estimates the torque of the MG; Equipped with 5. The temperature estimation system according to claim 4, wherein the first estimation unit has a map that defines the relationship between the rotational speed of the MG, the torque of the MG, the temperature of the cooling water, the temperature of the atmosphere, and the temperature of the directly connected part, and estimates the temperature of the directly connected part by applying the rotational speed acquired by the rotational speed acquisition unit, the torque estimated by the torque estimation unit, the temperature of the cooling water acquired by the cooling water temperature acquisition unit, and the temperature of the atmosphere acquired by the atmosphere temperature acquisition unit to the map.

6. 3. The temperature estimation system according to claim 1, wherein the first temperature acquisition unit (61A) estimates and acquires the temperature of the directly connected part based on any one of an estimated torque of the engine, an exhaust temperature of the engine, and a coolant temperature of the engine.

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