Motor controller

Abstract

To provide a motor controller capable of appropriately estimating temperature.SOLUTION: An electronic control unit (ECU) 40 comprises a drive circuit and a control unit 50. The drive circuit has a drive element which switches power supply to a motor. The control unit 50 has: a motor driving condition acquisition unit 53 which acquires a driving condition of the motor; a temperature calculation unit 581 which calculates, based on a detection value by a thermistor 45, a peripheral temperature of the drive element as a reference temperature Tb; and a temperature estimation unit 582 which estimates an element temperature, which is the temperature of the drive element. If it is determined that the motor has been driven, then the temperature estimation unit 582 estimates a rise in the temperature based on the motor driving condition and the reference temperature Tb. If it is determined that the motor has not been driven, then the temperature estimation unit estimates a decrease in the temperature based on the reference temperature Tb. The temperature estimation unit 582 updates an estimated element temperature Tm, which is an estimated value of the element temperature, based on an added value or a subtracted value.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a motor control device. [Background technology]

[0002] Conventionally, there is known a control device for a range switching mechanism that switches a shift range using a motor as a drive source. For example, in Patent Document 1, an operation counter counts the number of times that range switching operations are performed consecutively with short operation intervals less than a predetermined time, and when the count value reaches a predetermined value, the control switches from normal control to heat generation suppression control and temporarily prohibits the supply of electricity to the motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4999395 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, temperature detection is not performed. Therefore, in order to be effective even in a high temperature environment, it is necessary to set a strict upper limit on the number of range switching times, which reduces the number of possible switching times compared to the original number. In addition, it may be difficult to directly detect the temperature of the driving element due to the mounting conditions.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a motor control device that can appropriately estimate a drive element temperature. [Means for solving the problem]

[0006] The motor control device of the present invention includes a drive circuit (41) and a control unit (50). The drive circuit has a drive element that switches power supply to the motor (10). The control unit has a drive state acquisition unit (53) that acquires the drive state of the motor, a reference temperature calculation unit (581) that calculates the ambient temperature of the drive element as a reference temperature based on a detection value of the temperature sensor (45), and a temperature estimation unit (582) that estimates an element temperature, which is the temperature of the drive element.

[0007] The temperature estimator estimates the rising temperature based on the driving state of the motor and the reference temperature when it is determined that the motor is being driven, and estimates the falling temperature based on the reference temperature when it is determined that the motor is not being driven. The temperature estimator updates the estimated value of the element temperature based on the rising temperature or the falling temperature. This makes it possible to appropriately estimate the temperature of the driving element. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating a shift-by-wire system according to an embodiment. [Diagram 2] FIG. 2 is a block diagram illustrating a control unit according to one embodiment. [Diagram 3] 1 is a flowchart illustrating a temperature estimation process according to an embodiment. [Figure 4] 4 is a time chart illustrating setting of an initial value of an estimated element temperature according to an embodiment. [Diagram 5] FIG. 11 is an explanatory diagram illustrating an additional value according to one embodiment. [Figure 6] FIG. 11 is an explanatory diagram illustrating a subtraction value according to an embodiment. [Figure 7] FIG. 11 is an explanatory diagram illustrating a subtraction value according to an embodiment. [Figure 8] 10 is a flowchart illustrating a reference temperature setting process according to an embodiment. [Figure 9] 1 is a flowchart illustrating a fever determination process according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (One embodiment) A motor control device according to the present invention will now be described with reference to the drawings. A motor control device according to one embodiment is shown in Figs. 1 to 9. As shown in Fig. 1, an ECU 40 as a motor control device is applied to, for example, a shift-by-wire system 1. The shift-by-wire system 1 includes a motor 10, a detent mechanism 20, a parking lock mechanism 30, and the ECU 40.

[0010] The motor 10 is, for example, a switched reluctance motor, which rotates when power is supplied from a battery mounted on a vehicle (not shown), and functions as a drive source for the detent mechanism 20. The motor 10 is provided with a rotation angle sensor, such as an encoder, that detects the rotation position.

[0011] The rotation of the motor 10 is output to an output shaft 15 via a reducer (not shown). In this way, the rotation of the motor 10 is transmitted to a detent mechanism 20. An output shaft sensor 16 that detects the angle of the output shaft 15 is provided on the output shaft 15.

[0012] The detent mechanism 20 has a detent plate 21, a detent spring 25, a detent roller 26, etc., and transmits the rotational driving force output from the reduction gear to a manual valve 28 and a parking lock mechanism 30.

[0013] The detent plate 21 is fixed to the output shaft 15 and driven by the motor 10. On the side of the detent spring 25 of the detent plate 21, four valleys 22 corresponding to each of the ranges P (parking), R (reverse), N (neutral), and D (drive) are formed.

[0014] The detent plate 21 is provided with a pin 24 that protrudes parallel to the output shaft 15. The pin 24 is connected to a manual valve 28. When the detent plate 21 is driven by the motor 10, the manual valve 28 moves back and forth in the axial direction. In other words, the detent mechanism 20 converts the rotational motion of the motor 10 into linear motion and transmits it to the manual valve 28. The manual valve 28 is provided in a valve body 29. When the manual valve 28 moves back and forth in the axial direction, a hydraulic supply path to a hydraulic clutch (not shown) is switched, and the engagement state of the hydraulic clutch is switched to change the shift range.

[0015] The detent spring 25 is an elastically deformable plate-like member, and has a detent roller 26 provided at its tip. The detent spring 25 urges the detent roller 26 toward the rotation center of the detent plate 21. When a rotational force of a predetermined magnitude or more is applied to the detent plate 21, the detent spring 25 elastically deforms, and the detent roller 26 moves between the valleys 22. When the detent roller 26 fits into one of the valleys 22, the oscillation of the detent plate 21 is restricted, the axial position of the manual valve 28 and the state of the parking lock mechanism 30 are determined, and the shift range is fixed.

[0016] The parking lock mechanism 30 has a parking rod 31, a cone 32, a parking lock pole 33, a shaft 34, and a parking gear 35. The parking rod 31 is formed in a substantially L-shape, and one end 311 is fixed to the detent plate 21. The other end 312 of the parking rod 31 is provided with the cone 32. The cone 32 is formed so as to have a smaller diameter as it approaches the other end 312.

[0017] The parking lock pole 33 abuts against the conical surface of the cone 32 and is provided so as to be swingable about a shaft 34. A protrusion 331 capable of meshing with the parking gear 35 is provided on the parking lock pole 33 on the parking gear 35 side. When the cone 32 moves in the P direction due to rotation of the detent plate 21, the parking lock pole 33 is pushed up and the protrusion 331 meshes with the parking gear 35. On the other hand, when the cone 32 moves in the NotP direction, the meshing between the protrusion 331 and the parking gear 35 is released.

[0018] The parking gear 35 is provided on an axle (not shown) so as to be able to mesh with a protrusion 331 of the parking lock pole 33. When the parking gear 35 meshes with the protrusion 331, the rotation of the axle is restricted. When the shift range is a NotP range other than the P range, the parking gear 35 is not locked by the parking lock pole 33, and the rotation of the axle is not hindered by the parking lock mechanism 30. When the shift range is the P range, the parking gear 35 is locked by the parking lock pole 33, and the rotation of the axle is restricted.

[0019] The ECU 40 includes a drive circuit 41, a thermistor 45, and a control unit 50. The drive circuit 41 includes a drive element (not shown) and switches the current supply to the motor windings by switching the drive element. The thermistor 45 is mounted on the same board as the drive element and detects the board temperature as the ambient temperature of the drive element.

[0020] The control unit 50 is mainly composed of a microcomputer and includes a CPU, ROM, RAM, I / O, and bus lines connecting these components (all not shown). Each process in the control unit 50 may be software processing in which the CPU executes a program stored in advance in a substantial memory device (i.e., a readable non-transitory tangible recording medium) such as a ROM, or may be hardware processing in which a dedicated electronic circuit is used.

[0021] The control unit 50 has a drive control unit 51, a voltage detection unit 52, a motor drive state acquisition unit 53, an ECU state determination unit 54, a fault determination unit 55, and a heat generation determination processing unit 58. The drive control unit 51 controls the on / off operation of the drive elements of the drive circuit 41 to control the drive of the motor 10. The voltage detection unit 52 detects an applied voltage V applied to the drive circuit 41. In this embodiment, the applied voltage V is a battery voltage detected by a voltage sensor (not shown).

[0022] The motor drive status acquisition unit 53 acquires the drive status of the motor 10. The drive status of the motor 10 includes whether the motor 10 is driven or not, and if the motor is driven, includes information related to the drive mode and the shift range before and after switching. The ECU status determination unit 54 determines the startup status of the ECU 40. After the termination determination of the ECU 40, various processes such as termination processing can be executed by the control unit 50 during the termination processing implementation time. The failure determination unit 55 detects a failure of the thermistor 45.

[0023] 2, the heat generation determination processing unit 58 has a reference temperature calculation unit 581, a temperature estimation unit 582, and a heat generation determination unit 583. The reference temperature calculation unit 581 calculates a reference temperature Tb based on a detection value of the thermistor 45. In this embodiment, the reference temperature Tb is the substrate temperature. The calculation of the reference temperature Tb will be described later.

[0024] The temperature estimation unit 582 estimates the temperature of the drive element based on the reference temperature Tb, the failure determination of the thermistor 45, the driving state of the motor 10, etc. Hereinafter, the estimated value of the drive element temperature is referred to as the estimated element temperature Tm. The heat generation determination unit 583 performs heat generation determination of the drive element based on the estimated element temperature Tm.

[0025] In the shift-by-wire system 1, if the driver frequently repeats unnecessary range switching operations, there is a risk that the temperature of the motor 10 and the driving elements will rise. For example, in order to suppress the temperature rise, the number of consecutive operations at short operation intervals is counted, and when the count value reaches a predetermined value, the control is switched from normal control to heat generation suppression control (e.g., motor current prohibition). However, when switching to heat generation suppression control based on the count value without detecting the temperature, it is necessary to set the number of times on the stricter scale so that the control is valid even in a high-temperature environment, and the number of times that switching is possible is reduced from the number of times that is originally possible.

[0026] Furthermore, if heat generation from the drive element is more severe than heat generation from the motor 10, the number of possible switching times may be further limited in anticipation of heat generation from the drive element, but it is difficult to measure the temperature of the drive element itself due to its installation. Therefore, in this embodiment, the temperature of the drive element is estimated from the reference temperature Tb, and heat generation determination is performed based on the estimated element temperature Tm, thereby making it possible to set an appropriate number of possible switching times and to increase the number of possible operations compared to switching to heat generation suppression control based on a count value.

[0027] The temperature estimation process of this embodiment will be described with reference to the flowchart of Fig. 3. This process is performed at a predetermined cycle by the control unit 50. Hereinafter, the "step" such as step S101 will be omitted and simply denoted by the symbol "S".

[0028] In S101, the control unit 50 determines whether or not it is startup of the ECU 40. If it is determined that it is not startup of the ECU 40 (S101: NO), the process proceeds to S104. If it is determined that it is startup of the ECU 40 (S101: YES), the process proceeds to S102, and the end element temperature Tm_f and the end reference temperature Tb_f written in S105 are read out.

[0029] In S103, the heat generation determination processing unit 58 sets the initial value Tm_i of the element temperature. The setting of the initial value Tm_i will be described with reference to FIG. 4. In FIG. 4, the horizontal axis represents time and the vertical axis represents temperature, but the time scale does not necessarily match the actual one. Also, the reference temperature Tb is shown by a solid line and the estimated element temperature Tm is shown by a one-dot chain line. Let the reference temperature at the time of power-off of the ECU 40 be the end reference temperature Tb_f, the reference temperature at the time of power-on be the start reference temperature Tb_w, and the value obtained by subtracting the start reference temperature Tb_w from the end reference temperature Tb_f be the reference temperature decrease amount ΔTb (see Equation (1)).

[0030] ΔTb = Tb_f - Tb_w ···(1)

[0031] When the power of the ECU 40 is turned off at time x11 and then turned on at time x12, if the reference temperature decrease amount ΔTb is greater than the temperature decrease determination threshold value Tb_th, it means that sufficient time has passed for the driving element to cool down since the previous power-off, and there is a high probability that the estimated element temperature Tm that has risen due to energization has dropped to about the same level as the reference temperature Tb. Therefore, the initial value Tm_i of the element temperature is set to the start reference temperature Tb_w.

[0032] When the power of the ECU 40 is turned off at time x13 and then turned on at time x14, if the reference temperature decrease amount ΔTb is less than or equal to the temperature decrease determination threshold value Tb_th, it means that not much time has passed since the previous power-off, and there is a high probability that the estimated element temperature Tm that has risen due to energization has not dropped to the reference temperature Tb. Therefore, the initial value Tm_i of the element temperature is set to the end element temperature Tm_f.

[0033] When the power of the ECU 40 is turned off at time x15 and then turned on at time x16, if the start reference temperature Tb_w is higher than the end reference temperature Tb_f due to an increase in the outside air temperature or the like, the higher value of the end element temperature Tm_f or the start reference temperature Tb_w is set as the initial value Tm_i of the element temperature. In this example, since Tm_f < Tb_w, the initial value Tm_i of the element temperature is set to the start reference temperature Tb_w.

[0034] 3, in S104, which is reached when a negative determination is made in S101, the control unit 50 determines whether or not it is time to terminate the ECU 40. If it is determined that it is time to terminate the ECU 40 (S104: YES), the process proceeds to S105, in which the current element temperature is set as the termination element temperature Tm_f and the reference temperature is set as the termination reference temperature Tb_f and are written into the temperature storage unit 59, which is a non-volatile memory. If it is determined that it is not time to terminate the ECU 40 (S104: NO), the process proceeds to S106.

[0035] In S106, the heat generation determination processor 58 determines whether or not the motor 10 has been driven. If it is determined that the motor 10 has not been driven (S106: NO), the process proceeds to S108. If it is determined that the motor 10 has been driven (S106: YES), the process proceeds to S107.

[0036] In S107, the heat generation determination processing unit 58 reads the additional value AD, and adds the additional value AD to the previous value of the estimated element temperature Tm to obtain the current value of the estimated element temperature Tm (see formula (2)). The subscript (n) indicates the current value, and (n-1) indicates the previous value.

[0037] The additional value AD is a value that is set based on the temperature rise of the driving element during one drive of the motor 10, for example, one range switching. As shown in Fig. 5, the additional value AD is calculated using the applied voltage V, the temperature deviation ΔT (see formula (3)) that is the value obtained by subtracting the reference temperature Tb from the estimated element temperature Tm, and the driving state of the motor 10 as arguments. The map in Fig. 5 is an example, and the number of threshold values, etc. can be set appropriately. The same applies to Figs. 6 and 7.

[0038] Tm (n) =Tm (n-1) +AD ···(2) ΔT = Tm - Tb (3)

[0039] When the applied voltage V is less than the voltage determination threshold value Vth, use the upper part of the map, and set the addition value AD = UPWL1 during wall contact driving and the addition value AD = UPCP1 during switching driving. When the applied voltage V is greater than or equal to the voltage determination threshold value Vth, use the lower part of the map, and set the addition value AD = UPWL2 during wall contact driving and the addition value AD = UPCP2 during switching driving. When the applied voltage V is large, the estimated element temperature Tm tends to rise. Therefore, the value UPWL2 is relatively larger than the value UPWL1, and the value UPCP2 is relatively larger than the value UPCP1.

[0040] The magnitude relationship of the threshold values a, b, and c related to the temperature deviation ΔT is a < b < c. That is, when ΔT < a, the difference between the estimated element temperature Tm and the reference temperature Tb is relatively small, and when ΔT ≥ c, the difference between the estimated element temperature Tm and the reference temperature Tb is relatively large. For example, when the applied voltage V < Vth and the driving state of the motor 10 is wall contact, the addition value AD = UPWL1_1 is the largest when ΔT < a, followed by UPWL1_2 and UPWL1_3, and the value UPWL1_4 when ΔT ≥ c is the smallest. That is, when the ambient temperature is low with respect to the driving element temperature, since the driving element is less likely to heat up due to energization, the addition value AD is made relatively small. The same applies to cases other than wall contact driving when the applied voltage V ≥ Vth.

[0041] The driving state of the motor 10 includes wall contact driving and switching driving for each range. In wall contact driving, the detent roller 26 is moved to the driving limit on the P side or D side, and learning is performed with the wall position as the reference position. In wall contact driving, in order to suppress the impact when the detent roller 26 contacts the wall, torque suppression control is used, so the heat generation amount is larger than that in normal range switching driving. Therefore, if the applied voltage V and the temperature deviation ΔT are the same, the addition value AD = UPLW during wall contact driving is relatively larger than the addition value AD = UPCP during switching.

[0042] In the switching drive of each range, an additional value according to the range switching angle is set. For example, at the time of PD switching, the switching angle is larger than at the time of other range switching, and the energization time is longer, so the additional value AD at the time of PD switching is set relatively larger than at the time of other range switching. Also, for example, when the RN switching angle and the ND switching angle are equal, the values ​​may be equal, such as UPCP1_5=UPCP1_9. Note that, since the switching time becomes longer as the switching angle becomes larger, it can also be considered that the additional value AD is set according to the range switching time. Also, instead of map calculation, the additional value AD may be determined by a mathematical calculation using the range switching angle, range switching time, etc.

[0043] 3, in S108, which is reached when a negative determination is made in S106, the heat generation determination processor 58 determines whether the elapsed time Xstop since the drive of the motor 10 was stopped is less than the first stop determination time Xth1. If it is determined that the elapsed time Xstop since the drive was stopped is less than the first stop determination time Xth1 (S108: YES), the process proceeds to S109. In S109, the heat generation determination processor 58 reads the subtraction value SU1, and subtracts the subtraction value SU1 from the previous value of the estimated element temperature Tm to obtain the current value of the estimated element temperature Tm (equation (4)).

[0044] If it is determined that the elapsed time Xstop from the stop of the motor 10 is equal to or longer than the first stop judgment time Xth1 (S108: NO), the process proceeds to S110. In S110, the heat generation determination processor 58 determines whether the elapsed time Xstop from the stop of the motor 10 is shorter than the second stop judgment time Xth2. The second stop judgment time Xth2 is set to a value longer than the first stop judgment time Xth1. If it is determined that the elapsed time Xstop from the stop of the motor 10 is equal to or longer than the first stop judgment time Xth1 and shorter than the second stop judgment time Xth2 (S110: YES), the process proceeds to S111. In S111, the heat generation determination processor 58 reads the subtraction value SU2, and subtracts the subtraction value SU2 from the previous value of the estimated element temperature Tm to obtain the current value of the estimated element temperature Tm (Equation (5)). When it is determined that the elapsed time Xstop from when driving was stopped is equal to or longer than the second stop determination time Xth2 (S110: NO), the process proceeds to S112, and the estimated element temperature Tm is set as the reference temperature Tb.

[0045] Tm (n) =Tm (n-1) -SU1 ···(4) Tm (n) =Tm (n-1) -SU2 (5)

[0046] The subtraction values ​​SU1 and SU2 are values ​​that are set according to the elapsed time Xstop from when the motor 10 is stopped. Immediately after the motor 10 is stopped, the drop in the estimated element temperature per unit time Xi (for example, 0.5 [s]) is relatively large, and the drop becomes smaller as time passes from when the motor 10 is stopped. Therefore, in this embodiment, the subtraction values ​​are set so that the smaller the elapsed time Xstop from when the motor 10 is stopped, the larger the subtraction value becomes. In other words, when the temperature deviation ΔT is equal, SU1>SU2. Here, the subtraction value SU is set to two levels, but it may be set to three or more levels, or the subtraction value SU may be determined by a mathematical calculation using the elapsed time Xstop.

[0047] The subtraction value SU1 is shown in FIG. 6, and the subtraction value SU2 is shown in FIG. 7. The magnitude relationship of the thresholds d, e, f, and g related to the temperature deviation ΔT is d < e < f < g. That is, when ΔT < d, the difference between the estimated element temperature Tm and the reference temperature Tb is relatively small, and when ΔT ≥ g, the difference between the estimated element temperature Tm and the reference temperature Tb is relatively large.

[0048] As shown in FIG. 6, when ΔT < d, the subtraction value SU1 is set to 0. Also, in ascending order, they are DWN1_1, DWN1_2, DWN1_3, and the value DWN1_4 when ΔT ≥ g is the largest. As shown in FIG. 7, when ΔT < d, the subtraction value SU2 is set to 0. Also, in ascending order, they are DWN2_1, DWN2_2, DWN2_3, and the value DWN2_4 when ΔT ≥ g is the largest. That is, when the ambient temperature is low with respect to the driving element temperature, the temperature is likely to decrease in the non-energized state, so the subtraction value SU is made relatively large.

[0049] The reference temperature setting process will be described based on the flowchart of FIG. 8. In S201, the reference temperature calculation unit 581 acquires a detection value from the thermistor 45. In S202, the reference temperature calculation unit 581 determines whether the detection value of the thermistor 45 is normal. If it is determined that the detection value of the thermistor 45 is normal (S202: YES), the process proceeds to S203. If it is determined that the detection value of the thermistor 45 is abnormal (S202: NO), the process proceeds to S204.

[0050] In S203, the reference temperature calculation unit 581 calculates the reference temperature Tb based on the detection value of the thermistor 45. When the thermistor 45 is composed of a plurality of (for example, two) detection elements, the average value is used as the reference temperature Tb. Also, an operation value or representative value other than the average value may be used as the reference temperature Tb.

[0051] In S204, the reference temperature calculation unit 581 does not use the detection value of the thermistor 45, but sets the reference temperature Tb to a predetermined value. In this embodiment, the maximum temperature Tb_max (e.g., 90°C) detected when the thermistor 45 is normal is set as the reference temperature Tb. This makes it possible to estimate the temperature of the driving element even if the thermistor 45 breaks down. Also, by assuming the worst case scenario and setting the reference temperature Tb to the maximum temperature Tb_max, it is possible to prevent thermal destruction of the driving element. The set reference temperature Tb is used to calculate the estimated element temperature Tm.

[0052] The heat generation determination process will be described with reference to the flowchart of FIG. 9. In S301, the heat generation determination unit 583 determines whether the estimated element temperature Tm is higher than the guard temperature Tg. The guard temperature Tg is set according to the temperature at which thermal destruction of the drive element occurs so that the drive element is not thermally destroyed. It is determined whether the estimated element temperature Tm is higher than the guard temperature Tg. If it is determined that the estimated element temperature Tm is higher than the guard temperature Tg (S301: YES), the process proceeds to S302, where the heat generation determination flag Flg_h is turned on. If it is determined that the estimated element temperature Tm is equal to or lower than the guard temperature Tg (S301: NO), the process proceeds to S303, where the heat generation determination flag Flg_h is turned off.

[0053] The heat generation determination flag Flg_h is sent to the drive control unit 51. When the heat generation determination flag Flg_h is off, the drive control unit 51 performs range switching under normal control, and when the heat generation determination flag Flg_h is on, the drive control unit 51 performs heat generation suppression control. In this embodiment, the heat generation suppression control prohibits range switching.

[0054] As described above, the ECU 40 includes the drive circuit 41 and the control unit 50. The drive circuit 41 has a drive element that switches the power supply to the motor 10. The control unit 50 has a motor drive state acquisition unit 53 that acquires the drive state of the motor 10, a reference temperature calculation unit 581 that calculates the ambient temperature of the drive element as a reference temperature Tb based on the detection value of the thermistor 45, and a temperature estimation unit 582 that estimates the element temperature, which is the temperature of the drive element.

[0055] The temperature estimation unit 582 estimates the rising temperature based on the driving state of the motor and the reference temperature Tb when it is determined that the motor is being driven, and estimates the falling temperature based on the reference temperature Tb when it is determined that the motor is not being driven. The temperature estimation unit 582 updates the estimated element temperature Tm, which is an estimate of the element temperature, based on the addition value AD or the subtraction value SU. In detail, the estimated element temperature Tm is calculated by adding the addition value AD or subtracting the subtraction value SU.

[0056] This makes it possible to appropriately estimate the temperature of the drive element. For example, when the ECU 40 is applied to the shift-by-wire system 1, the number of possible range changes in a normally used temperature range can be increased compared to a case in which the upper limit number of range changes in a short period of time is set assuming the worst case conditions without estimating the element temperature.

[0057] The additional value AD used for estimating the element temperature when it is determined that the motor is driven is estimated based on the temperature deviation ΔT, which is the difference between the estimated element temperature Tm and the reference temperature Tb. Here, the estimated element temperature Tm used for calculating the additional value AD is a previous value or an initial value, and the additional value AD is used to calculate the current value of the estimated element temperature Tm. In this embodiment, the additional value AD is a value per drive of the motor 10, which is driven intermittently, and is a value per range switching or wall hitting in the shift-by-wire system 1. This makes it possible to calculate the estimated element temperature Tm during motor driving by a relatively simple calculation without using a current detection value or the like.

[0058] The control unit 50 has a voltage detection unit 52 that detects the applied voltage applied to the drive circuit 41. The additional value AD is estimated based on the applied voltage V. This makes it possible to more appropriately calculate the estimated element temperature Tm when the motor is driven.

[0059] The drive state of the motor 10 includes a range switching angle or a range switching time. The additional value AD is estimated based on the range switching angle or the range switching time in the current range switching. The drive state of the motor 10 includes range switching drive and wall hitting drive. The additional value AD is estimated depending on whether the drive state of the motor 10 is range switching drive or wall hitting drive. This makes it possible to accurately estimate the temperature of the drive element in the shift-by-wire system 1, thereby increasing the number of possible switches.

[0060] The subtraction value SU used to estimate the element temperature when it is determined that the motor is not being driven is estimated based on the difference between the estimated element temperature Tm and the reference temperature Tb. Here, the estimated element temperature Tm used to calculate the subtraction value SU is the previous value or the initial value, and the subtraction value SU can be used to calculate the current value of the estimated element temperature Tm. The subtraction value SU is also estimated based on the elapsed time Xstop from the end of driving of the motor 10, so that the shorter the elapsed time Xstop, the larger the subtraction value SU becomes. This makes it possible to properly calculate the estimated element temperature Tm when the motor is not being driven.

[0061] The control unit 50 has a failure determination unit 55 that determines whether the thermistor 45 has a failure. If the thermistor 45 has a failure, the temperature estimation unit 582 sets the reference temperature Tb as a predetermined value. In this embodiment, the predetermined value is a value that is set according to the worst-case conditions, and is set to the maximum temperature Tb_max. This makes it possible to continue range switching while preventing thermal destruction of the driving element, even if the thermistor 45 has a failure.

[0062] The motor 10 is an actuator related to switching of the shift range, and when the estimated element temperature Tm is higher than the guard temperature Tg, range switching is prohibited, thereby making it possible to prevent thermal destruction of the drive element.

[0063] The control unit 50 has a temperature storage unit 59 that stores an end element temperature Tm_f, which is the element temperature when the power supply to the ECU 40 is turned off, and an end reference temperature Tb_f, which is the reference temperature when the power supply is turned off.

[0064] If the amount of temperature drop in the reference temperature between turning the power of the ECU 40 off and then on again is greater than the judgment threshold, i.e., if the amount of reference temperature drop ΔTb>Tb_th, the temperature estimation unit 582 sets the initial value Tm_i of the element temperature at power on to the startup reference temperature Tb_w, which is the reference temperature at power on. Also, if the amount of temperature drop in the reference temperature between turning the power of the ECU 40 off and then on again is equal to or less than the judgment threshold, i.e., 0≦ΔTb≦Tb_th, the temperature estimation unit 582 sets the initial value Tm_i of the element temperature at power on to the termination element temperature Tm_f.

[0065] In addition, since the element temperature does not fall below the reference temperature, when the start-up reference temperature Tb_w is higher than the end-up element temperature Tm_f, the temperature estimation unit 582 sets the initial value Tm_i of the element temperature at power-on to the start-up reference temperature Tb_w. This makes it possible to appropriately set the initial value Tm_i of the element temperature at power-on, and to appropriately calculate the estimated element temperature Tm.

[0066] Furthermore, regardless of the reference temperature drop amount ΔTb, the initial value Tm_i of the element temperature at the time of power-on may be set as the end element temperature Tm_f. This makes it possible to prevent thermal destruction even if the ECU 40 is immediately restarted.

[0067] In the embodiment, the ECU 40 corresponds to the “motor control device”, the thermistor 45 corresponds to the “temperature sensor”, and the motor drive state acquisition unit 53 corresponds to the “drive state acquisition unit”. Also, the addition value AD corresponds to the “rising temperature”, the subtraction value SU corresponds to the “falling temperature”, the temperature drop determination threshold Tb_th corresponds to the “determination threshold (related to the determination of the amount of temperature drop)”, the guard temperature Tg corresponds to the “high temperature determination threshold”, and the wall hitting drive corresponds to the “reference position learning drive”.

[0068] (Other embodiments) In the above embodiment, an SR motor is exemplified as the motor. In other embodiments, the motor may be something other than an SR motor, such as a brushless DC motor. In the above embodiment, the temperature sensor is a thermistor. In other embodiments, the temperature sensor may be something other than a thermistor. Also, in the above embodiment, the temperature sensor is mounted on the same board as the drive element. In other embodiments, the temperature sensor may be provided in a location other than the same board as the drive element, as long as it is possible to detect the ambient temperature of the drive element. Also, temperature information used in another device may be obtained by communication or the like and used.

[0069] In the above embodiment, the detent plate is formed with four valleys corresponding to each range. In other embodiments, the number of valleys on the detent plate is not limited to four and may be any number equal to or greater than two. Also, the configurations and arrangements of the detent mechanism and the parking lock mechanism may be different from those of the above embodiment.

[0070] In the above embodiment, the motor control device is applied to a shift-by-wire system related to switching of a shift range. In other embodiments, the motor control device may be applied to an in-vehicle device other than a shift-by-wire system. Also, the motor control device may be applied to a device other than an in-vehicle device.

[0071] The disclosure regarding the point that "the motor is an actuator for switching the shift range, the drive state of the motor includes range switching drive and reference position learning drive, and the increased temperature is estimated depending on whether the drive state of the motor is the range switching drive or the reference position learning drive" may be combined with each disclosure related to a motor control device.

[0072] The disclosure regarding the point that "the falling temperature is estimated based on the difference between the element temperature and the reference temperature" may be combined with each disclosure related to a motor control device.

[0073] The disclosure regarding the point that "the control unit has a failure determination unit (55) that determines a failure of the temperature sensor, and the temperature estimation unit sets the reference temperature to a predetermined value when the temperature sensor is faulty" may be combined with each disclosure related to a motor control device.

[0074] The disclosure regarding "the motor is an actuator for switching the shift range, and when the estimated value of the element temperature is higher than a high temperature determination threshold, range switching is prohibited" may be combined with each disclosure related to a motor control device.

[0075] The disclosure regarding the point that "the control unit has a temperature memory unit (59) that stores an end element temperature, which is the element temperature when the power is turned off, and the temperature estimation unit sets the initial value of the element temperature when the power is turned on as the end element temperature" may be combined with each disclosure related to a motor control device.

[0076] The disclosure regarding the point that "the control unit has a temperature memory unit (59) that stores an end element temperature, which is the element temperature when the power is turned off, and an end reference temperature, which is the reference temperature when the power is turned off, and the temperature estimation unit sets the initial value of the element temperature at power on to the reference temperature at power on when an amount of temperature drop in the reference temperature between turning the power off and turning it on again is greater than a judgment threshold, and sets the initial value of the element temperature at power on to the end element temperature when an amount of temperature drop in the reference temperature between turning the power off and turning it on again is equal to or less than the judgment threshold" may be combined with each disclosure related to a motor control device.

[0077] The disclosure regarding the point that "the control unit has a temperature memory unit (59) that stores an end element temperature which is an estimated value of the element temperature when the power is turned off, and when the reference temperature when the power is turned on is higher than the end element temperature, the temperature estimation unit sets the initial value of the element temperature when the power is turned on to the reference temperature when the power is turned on" may be combined with each disclosure related to a motor control device.

[0078] The control unit and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transient tangible recording medium as instructions executed by a computer. As described above, the present invention is not limited to the above embodiment, and can be implemented in various forms within the scope of the invention. [Explanation of symbols]

[0079] 1. Shift-by-wire system 10. Motor 40···ECU (Motor Control Unit) 41 Drive circuit 45···Thermistor (temperature sensor) 50...Control section 51 Drive control unit 53 Motor drive status acquisition unit (drive status acquisition unit) 58 Fever determination processing unit 581...Reference temperature calculation section 582...Temperature estimation section

Claims

1. A drive circuit (41) having a drive element for switching the energization to a motor (10), a drive state acquisition unit (53) for acquiring the drive state of the motor, a reference temperature calculation unit (581) for calculating, based on the detection value of a temperature sensor (45), the ambient temperature of the drive element as a reference temperature, and a temperature estimation unit (582) for estimating the element temperature which is the temperature of the drive element, and a control unit (50); comprising the motor is an actuator related to the switching of a shift range, the temperature estimation unit when it is determined that motor driving is being performed, estimates a rising temperature based on the drive state of the motor and the reference temperature, when it is determined that motor driving is not being performed, estimates a falling temperature based on the reference temperature, updates an estimated value of the element temperature based on the rising temperature or the falling temperature, the rising temperature is estimated based on the difference between the element temperature and the reference temperature, the rising temperature is a value set corresponding to one drive of the motor, and the larger the temperature deviation which is a value obtained by subtracting the reference temperature from the element temperature, the relatively smaller the rising temperature, a motor control device.

2. the control unit has a voltage detection unit (52) for detecting an applied voltage applied to the drive circuit, the rising temperature is estimated based on the applied voltage, the motor control device according to claim 1.

3. The drive state of the motor includes a range switching angle, the rising temperature is estimated based on the range switching angle in the current range switching, the motor control device according to claim 1 or 2.

4. The drive state of the motor includes a range switching time, the rising temperature is estimated based on the range switching time in the current range switching, the motor control device according to claim 1 or 2.

5. The driving states of the motor include range switching drive and reference position learning drive. The motor control device according to claim 1 or 2, wherein the rising temperature is estimated according to whether the driving state of the motor is the range switching drive or the reference position learning drive.

6. The motor control device according to claim 1, wherein the falling temperature is estimated based on the difference between the element temperature and the reference temperature.

7. The motor control device according to claim 6, wherein the falling temperature is estimated based on the elapsed time since the drive of the motor ended, and is estimated to be larger as the elapsed time is shorter.

8. The control unit has a failure determination unit (55) that determines a failure of the temperature sensor. The motor control device according to claim 1, wherein the temperature estimation unit sets the reference temperature to a predetermined value when the temperature sensor has failed.

9. The motor control device according to claim 1, wherein range switching is prohibited when the estimated value of the element temperature is higher than a high temperature determination threshold.

10. The control unit has a temperature storage unit (59) that stores the end element temperature, which is the estimated value of the element temperature when the power is turned off. The motor control device according to claim 1, wherein the temperature estimation unit sets the initial value of the element temperature when the power is turned on to the end element temperature.

11. The control unit has a temperature storage unit (59) that stores the end element temperature, which is the estimated value of the element temperature when the power is turned off, and the end reference temperature, which is the reference temperature when the power is turned off. The temperature estimation unit When the temperature drop amount of the reference temperature during the period from when the power is turned off to when it is turned on again is larger than a determination threshold, sets the initial value of the element temperature when the power is turned on to the reference temperature when the power is turned on. The motor control device according to claim 1, wherein when the temperature decrease amount of the reference temperature during the period from turning off the power supply to turning it on again is equal to or less than the determination threshold value, the initial value of the element temperature at the time of turning on the power supply is set to the element temperature at the end.

12. The control unit includes a temperature storage unit (59) that stores an end element temperature that is an estimated value of the element temperature when the power supply is turned off. The motor control device according to claim 1, wherein when the reference temperature at the time of turning on the power supply is higher than the end element temperature, the initial value of the element temperature at the time of turning on the power supply is set to the reference temperature at the time of turning on the power supply.

Images