Control device

Abstract

Provided is a control device for a motor including a temperature sensor that detects a temperature of each of parts of a motor, the parts including at least a coil of a stator of the motor, the control device including: a coil temperature estimation unit that calculates an estimated current temperature of the coil on the basis of temperature information acquired from the temperature sensor and operation state information related to an operation state of the motor; and a torque limitation unit that calculates at least one of a predicted future temperature value of the coil and a current temperature change rate of the coil, and calculates a torque limitation command for limiting the torque of the motor on the basis of the estimated current temperature and at least one of the predicted future temperature value and the current temperature change rate.

Description

Control device

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

[0002] While miniaturization and high efficiency are required for motors, it is necessary to estimate the coil temperature based on limited temperature sensor information from the perspective of the heat resistance of various components. However, this creates a problem of large estimation errors in the detected coil temperature, necessitating excessive temperature protection. To solve this problem, for example, Patent Document 1 discloses a control device that corrects the temperature estimate by adding a temperature correction value determined by the rotation speed to the estimate determined by current and ambient temperature information only under low-speed and low-load conditions.

[0003] Japanese Patent Application Laid-Open No. 2022-42060

[0004] In view of the technology described in Patent Document 1, it is necessary to further suppress excessive protection and achieve appropriate torque control.

[0005] A motor control device having a temperature sensor that detects the temperature of each part of the motor including at least the coil of the motor's stator, and having a coil temperature estimation unit that calculates an estimated current temperature of the coil based on temperature information obtained from the temperature sensor and operating state information related to the operating state of the motor, and a torque limiting unit that calculates at least one of a future temperature prediction value of the coil and a current temperature change rate of the coil, and calculates a limit torque command that limits the torque of the motor based on the estimated temperature and at least one of the temperature prediction value and the temperature change rate.

[0006] According to the present invention, it is possible to provide a control device that can suppress excessive temperature protection of the motor and achieve appropriate change of the torque limit value.

[0007] Overall configuration diagram of a control device according to one embodiment of the present invention. Overall configuration diagram of a coil temperature estimation unit according to one embodiment of the present invention. Overall configuration diagram of a coil temperature prediction unit according to one embodiment of the present invention. Overall configuration diagram of a coil temperature change rate calculation unit according to one embodiment of the present invention. First modification Second modification Third modification Fourth modification

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0009] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0010] (One embodiment and overall configuration) (Fig. 1) A control device 1 that controls the torque of a motor has a coil temperature estimation unit 20, a coil temperature prediction unit 30, a coil temperature change rate calculation unit 40, a torque limit coefficient map 13, a basic torque map 14, and a torque limit unit 50. The control device 1 acquires information detected by a plurality of sensors provided in the motor, and adjusts and calculates a limit torque command for limiting the torque of the motor.

[0011] The configuration of the control device 1 for calculating the limit torque command for the motor will now be described in detail. First, the control device 1 acquires, via each sensor, operating state information 11 relating to the operating state of the motor and various temperature sensor information 12. The various temperature sensor information 12 includes temperature information relating to the heating capacity due to the coil current and temperature information relating to the cooling capacity of the cooling water, which can be acquired by the temperature sensor among the sensors detecting the temperature of the coil in the stator.

[0012] The coil temperature estimation unit 20 calculates an estimate 21 of the current coil temperature of the motor based on the operating state information 11 and various temperature sensor information 12, and outputs the calculated estimate 21 of the current coil temperature to the torque limit coefficient map 13. Similarly, the coil temperature prediction unit 30 calculates a predicted future coil temperature 31 according to the heating and cooling characteristics of the coil based on the operating state information 11 and various temperature sensor information 12, and outputs the calculated predicted future coil temperature 31 to the torque limit coefficient map 13. The coil temperature change rate calculation unit 40 calculates a current coil temperature change rate 41 that indicates the trend of the current coil temperature change up to the current temperature state based on the various temperature sensor information 12, and outputs the calculated current coil temperature change rate 41 to the torque limit coefficient map 13.

[0013] The torque limiting coefficient map 13 calculates a torque limiting coefficient for limiting the torque of the motor based on the estimated value 21 of the current coil temperature, the predicted value 31 of the future coil temperature, and the current coil temperature change rate 41, and outputs the calculated torque limiting coefficient to the torque limiting unit 50.

[0014] The torque limit coefficient map 13 has a torque data map defined for each combination pattern of parameters, for example, the current coil temperature estimated value 21, the future coil temperature predicted value 31, and the current coil temperature change rate 41. By referring to this torque data map, it is possible to determine the torque limit coefficient according to the combination of each parameter. Note that instead of the torque data map, a predetermined calculation formula or the like may be used to determine the torque limit coefficient according to each parameter value.

[0015] The torque limiting unit 50 calculates a limit torque that limits the torque for the motor based on the basic torque obtained from the basic torque map 14, which has a map of basic torque information based on the motor's operating state information, and the torque limiting coefficient obtained from the torque limiting coefficient map 13, and generates a limit torque command 15 according to the calculation result.

[0016] By doing this, the torque limiting unit 50 can calculate a limit torque command for the motor based on each parameter value calculated by the coil temperature estimating unit 20, the coil temperature predicting unit 30, and the coil temperature change rate calculating unit 40, respectively.

[0017] This allows for the addition of not only the current coil temperature estimate value 21, which has conventionally been used to compensate for the temperature rise delay of sensors such as thermistors for the coil, but also a future coil temperature prediction value 31 that takes into account the temperature rise characteristics and cooling characteristics that represent the heating and heat dissipation state, and the current coil temperature change rate 41, so that the motor torque limit rate can be appropriately adjusted in accordance with the basic torque and torque map pattern depending on the operating state, thereby achieving optimal torque control.

[0018] Furthermore, by using the predicted temperature value as a variable for torque adjustment, it can function independently from systems such as temperature protection and fault diagnosis that use the current coil temperature estimate, and there is no impact on the current coil temperature estimate, allowing the safety margin of the temperature protection operation to be optimized and reliability to be improved. Furthermore, since the torque is adjusted based on multiple parameter values, torque changes can be made gradual, increasing the rate at which the required torque can be met. Furthermore, there is no need to increase the size of the motor to improve output in order to meet the required torque.

[0019] (Fig. 2) The temperature sensor information 12 (Fig. 1) acquired by the coil temperature estimation unit 20 includes main temperature sensor information 12b, which is coil temperature information detected by a sensor mounted on a bus bar connected to the coil inside the motor, and external temperature sensor information 12a, which is temperature information of parts of the motor other than the coil. The coil temperature estimation unit 20 has a temperature data table 201 and a temperature estimation value calculation unit 202.

[0020] The temperature data table 201 acquires the motor operating state information 11 and the external temperature sensor information 12a. Based on the temperature data table 201, data for estimating the coil temperature according to the acquired motor operating state information 11 and the external temperature sensor information 12a is calculated and output to the temperature estimation value calculation unit 202.

[0021] The temperature estimation value calculation unit 202 acquires the main temperature sensor information 12b, and can calculate the current coil temperature estimation value 21 based on the coil temperature indicated by the acquired main temperature sensor information 12b and data for temperature estimation acquired from the temperature data table 201. In this way, the coil temperature estimation unit 20 can estimate the current coil temperature based on the operating state information 11 and the external temperature sensor information 12a.

[0022] (FIG. 3) Coil temperature prediction unit 30 has a temperature rise characteristics calculation unit 301, a cooling characteristics calculation unit 302, and a temperature prediction value calculation unit 303. Temperature rise characteristics calculation unit 301 acquires motor operating state information 11, which is a command value to the motor, and based on this, calculates coil temperature rise characteristics (heat generation characteristics) corresponding to the current operating state of the motor, such as the motor output torque and the current flowing through the motor, and outputs the calculated temperature rise characteristics to temperature prediction value calculation unit 303.

[0023] The cooling characteristic calculation unit 302 acquires external temperature sensor information 12a, and based on this, calculates the cooling characteristics (heat dissipation characteristics) of the coil according to the temperature state of parts other than the coil of the motor, for example, the temperature of a cooling flow path provided for cooling the coil, and outputs the calculated cooling characteristics to the temperature prediction value calculation unit 303.

[0024] The temperature prediction value calculation unit 303 acquires the main temperature sensor information 12b and calculates a future coil temperature prediction value 31 based on the coil temperature represented by the main temperature sensor information 12b and the coil heating characteristics and coil cooling characteristics acquired from the heating characteristics calculation unit 301 and the cooling characteristics calculation unit 302, respectively.

[0025] As described above, the coil temperature prediction unit 30 calculates the future coil temperature prediction value 31 using the motor operating state information 11, which indicates the command value for the motor, and the external temperature sensor information 12a, which indicates the temperature state of the motor's parts other than the coil. This makes it possible to appropriately determine whether the future coil temperature will move in the heating direction or the heat dissipation direction, and to accurately calculate the future coil temperature prediction value 31 based on the determination result. Therefore, excessive temperature protection of the motor can be suppressed, and the torque can be maintained as large as possible within an appropriate temperature range, thereby improving the motor output per unit time and aiming to maximize output. In other words, optimal control can be achieved by adjusting the torque limit on the motor.

[0026] In addition, the temperature prediction value calculation unit 303 may calculate the future coil temperature prediction value 31 using the current coil temperature estimation value 21 (Figures 1 and 2) calculated by the coil temperature estimation unit 20, rather than the main temperature sensor information 12b.

[0027] (FIG. 4) Coil temperature change rate calculation unit 40 has a past information storage unit 401 and a temperature change rate calculation unit 402. Past information storage unit 401 accumulates coil temperature history data by acquiring and storing temperature sensor information 12 at predetermined time intervals. Temperature change rate calculation unit 402 acquires current temperature sensor information 12 and acquires past coil temperature history data from past information storage unit 401, and calculates the current coil temperature change rate 41 from these time-series changes.

[0028] The method of calculating the current coil temperature change rate 41 in the coil temperature change rate calculation unit 40 is, for example, an averaging process according to the amount of data stored in the past information storage unit 401, and a differentiation process of the current temperature sensor information 12 and the historical data of the coil temperature for a predetermined past period stored in the past information storage unit 401.

[0029] (First Modification) (FIG. 5) The control device 1 may calculate the limit torque command 15 based on the coil temperature estimated value 21 calculated by the coil temperature estimation unit 20 and the coil temperature change rate 41 calculated by the coil temperature change rate calculation unit 40, without using the future coil temperature predicted value 31 (see FIGS. 1 and 3) calculated by the coil temperature prediction unit 30 described above.

[0030] (Second modified example) (Figure 6) The control device 1 may calculate the limit torque command 15 based on the coil temperature estimated value 21 calculated by the coil temperature estimation unit 20 and the coil temperature predicted value 31 calculated by the coil temperature prediction unit 30, without using the coil temperature change rate 41 calculated by the coil temperature change rate calculation unit 40 described above (see Figures 1 and 4).

[0031] (Third Modification) (FIG. 7) In the control device 1, the motor operating state information 11 is used to calculate the future coil temperature predicted value 31 in the coil temperature prediction unit 30, but the current coil temperature estimated value 21 calculated in the coil temperature estimation unit 20 may be used without using the temperature sensor information 12.

[0032] (FIG. 8) In the control device 1, the coil temperature change rate calculation unit 40 may calculate the current coil temperature change rate 41 using the current coil temperature estimated value 21 calculated by the coil temperature estimation unit 20 without using the temperature sensor information 12.

[0033] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0034] (1) A motor control device 1 includes a temperature sensor that detects the temperature of each part of the motor, including at least the coil of the motor's stator, and includes a coil temperature estimation unit 20 that calculates an estimated current coil temperature 21 based on temperature sensor information 12 acquired from the temperature sensor and operating state information 11 related to the operating state of the motor, and a torque limiting unit 50 that calculates at least one of a predicted future coil temperature value 31 and a current coil temperature change rate 41, and calculates a limit torque command that limits the torque of the motor based on the estimated temperature 21 and at least one of the predicted temperature value 31 and the temperature change rate 41. In this way, a control device 1 can be provided that can suppress excessive temperature protection of the motor and appropriately change the torque limit value.

[0035] (2) The system includes a coil temperature prediction unit 30 that calculates a predicted future coil temperature value, and a coil temperature change rate calculation unit 40 that calculates a current coil temperature change rate. This allows for torque limit adjustment based on the parameter values ​​calculated by each unit.

[0036] (3) The temperature sensor information 12 includes main temperature sensor information 12b, which is temperature information about the coil, and external temperature sensor information 12a, which is temperature information about parts of the motor other than the coil, and the coil temperature estimator 20 estimates the current coil temperature based on the main temperature sensor information 12b, the operating state information 11, and the external temperature sensor information 12a. This improves the accuracy of the current estimated coil temperature 21.

[0037] (4) The coil temperature prediction unit 30 includes a temperature rise characteristic calculation unit 301 that calculates the temperature rise characteristic of the coil based on the operating state information, and a cooling characteristic calculation unit 302 that calculates the cooling characteristic of the coil based on the external temperature information, and calculates the temperature prediction value 31 based on the temperature rise characteristic and the cooling characteristic. In this way, optimal torque control can be achieved by taking into account the predicted future coil temperature.

[0038] The present invention is not limited to the above-described embodiments, and various modifications and combinations of other configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to those having all of the configurations described in the above-described embodiments, and includes those in which some of the configurations are omitted.

[0039] REFERENCE SIGNS LIST 1 Control device 11 Operating state information 12 Temperature sensor information 12a External temperature sensor information 12b Main temperature sensor information 13 Torque limit coefficient map 14 Basic torque map 15 Limit torque command 20 Coil temperature estimation unit 21 Estimated coil temperature 30 Coil temperature prediction unit 31 Predicted coil temperature value 40 Coil temperature change rate calculation unit 41 Coil temperature change rate 50 Torque limit unit 201 Temperature data table 202 Temperature estimated value calculation unit 301 Heating characteristic calculation unit 302 Cooling characteristic calculation unit 303 Temperature predicted value calculation unit 401 Past information storage unit 402 Temperature change rate calculation unit

Claims

1. A motor control device having a temperature sensor that detects the temperature of each part of the motor including at least a coil of a stator of the motor, the control device comprising: a coil temperature estimation unit that calculates an estimated temperature of the coil based on temperature information obtained from the temperature sensor and operating state information related to the operating state of the motor; a torque limiting unit that calculates at least one of a future temperature prediction value of the coil and a current temperature change rate of the coil; and a torque limiting unit that calculates a limit torque command to limit the torque of the motor based on the estimated temperature and at least one of the temperature prediction value and the temperature change rate.

2. The control device according to claim 1, further comprising: a coil temperature prediction unit that calculates a predicted future temperature value of the coil; and a coil temperature change rate calculation unit that calculates a current temperature change rate of the coil.

3. The control device described in claim 1, wherein the temperature information includes main temperature information, which is temperature information of the coil, and external temperature information, which is temperature information of parts of the motor other than the coil, and the coil temperature estimation unit estimates the current temperature of the coil based on the main temperature information, the operating state information, and the external temperature information.

4. The control device according to claim 3, wherein the coil temperature prediction unit includes a heating characteristic calculation unit that calculates the heating characteristic of the coil based on the operating state information, and a cooling characteristic calculation unit that calculates the cooling characteristic of the coil based on the external temperature information, and calculates the temperature prediction value based on the heating characteristic and the cooling characteristic.

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