Processing device and method for determining winding temperature calculation model

Abstract

The processing device obtains a first rising trend as the rising trend of the temperature of the winding and a second rising trend as the rising trend of the detected temperature of the temperature sensor in a state where a voltage application for raising the temperature of the winding to a specified temperature is being performed. Based on the second rising trend, a specified parameter is calculated to determine a specified temperature characteristic model, and based on the first rising trend, a winding-related parameter is calculated to determine a winding temperature characteristic model.

Description

Technical Field

[0001] The present invention relates to a technique for adjusting model parameters related to an electronic thermal relay of a motor. Background Art

[0002] Motors are used in various fields, and their operating conditions such as rotational speed and motor load also vary widely. In addition, the ambient atmosphere around the motor is not necessarily constant. Generally, if the ambient temperature around the motor rises, it becomes difficult to dissipate heat from the motor, and its operating environment becomes severe. When driving a motor, if it is placed in an overloaded environment, the winding temperature of the motor rises excessively, and sometimes the winding burns out. To avoid such winding burnout, there is a technique of embedding temperature sensors such as thermistors and thermostats in the motor and directly detecting the temperature of the winding through them to avoid overloading the motor (for example, see Patent Document 1). However, in such a case, it is necessary to embed a temperature sensor in the motor, and if the temperature sensor is not accurately placed at a specified position, it is difficult to appropriately detect the temperature of the winding.

[0003] On the other hand, techniques related to electronic thermal relays have been developed. These techniques do not use direct sensors such as temperature sensors, but calculate the load condition based on the current command flowing through the motor and determine overheating of the winding. In such an electronic thermal relay, overheating of the winding is judged by software. For example, in the technique shown in Patent Document 2, the winding resistance value is estimated based on parameters such as the voltage applied to the motor, the current, and the induced voltage of the motor, and the winding temperature is estimated based on the estimated winding resistance value. In addition, in the technique shown in Patent Document 3, the winding temperature at startup is estimated based on the winding resistance value measured at startup, and then the change in the winding temperature is estimated based on the current flowing through the motor.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Laid-Open No. 4-283087

[0007] Patent Document 2: Japanese Patent Laid-Open No. 2011-15584

[0008] Patent Document 3: Japanese Patent Laid-Open No. 9-261850 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] In order to use the electronic thermal relay technology to avoid excessive temperature rise of the winding, it is preferable that the specifications related to the motor are clear. That is, if physical parameters such as the resistance value of the winding associated with the temperature of the winding and the induced voltage of the motor are clear, the temperature of the winding can be estimated more accurately. However, in the case where the motor is driven by a driver, the physical parameters of the motor are not necessarily clear. Therefore, the suppression of overheating of the winding based on the electronic thermal relay technology has to be carried out on the basis of ensuring a safety margin, and there is a tendency to become excessive protection.

[0011] On the other hand, by arranging a temperature sensor on the winding of the motor to detect its temperature, it is also possible to achieve the suppression of overheating of the winding. However, as described above, the detection result depends to a large extent on the arrangement of the temperature sensor in the motor. Therefore, it is difficult to achieve high-precision winding protection. Even assuming an optimal arrangement, there is a certain heat capacity between the winding and the temperature sensor, and furthermore, the temperature sensor itself has a response delay. Therefore, the detection of the temperature sensor itself includes a delay. Therefore, in the case of using a temperature sensor, it is particularly difficult to detect a rapid temperature change caused by a large current in a timely manner.

[0012] The present application disclosure is completed in view of such problems, and its purpose is to provide a technology related to an electronic thermal relay of a motor that accurately estimates the temperature of the winding.

[0013] Means for solving the problem

[0014] In the present application disclosure, in order to solve the above problems, the following structure is adopted: The rising trend of the winding temperature when a specified voltage is applied and the rising trend of the detected temperature of the temperature sensor arranged to detect the winding temperature are used to determine the winding temperature characteristic model for the electronic thermal relay of the motor and the specified temperature characteristic model. In this way, by reflecting the detected value of the temperature sensor in the electronic thermal relay technology, the temperature of the motor winding can be estimated more accurately by the electronic thermal relay.

[0015] Specifically, the present disclosure is a processing device that determines a calculation model, which is a calculation model for estimating the temperature of a winding of an electronic thermal relay of a motor having a stator wound with a winding and a rotor. The calculation model includes: a winding temperature characteristic model that includes winding-related parameters associated with the temperature characteristics of the winding; and a specified temperature characteristic model that includes specified parameters associated with the characteristics of the temperature detected by a temperature sensor disposed near the winding. The processing device includes: a temperature change acquisition unit that acquires a first increase trend as the increase trend of the temperature of the winding and a second increase trend as the increase trend of the detected temperature of the temperature sensor in a state where a voltage is applied to increase the temperature of the winding to a specified temperature; and a determination unit that calculates the specified parameters based on the second increase trend to determine the specified temperature characteristic model, and calculates the winding-related parameters based on the first increase trend to determine the winding temperature characteristic model.

[0016] The processing device of the present disclosure is configured to suppress overheating of the winding of a motor having a temperature sensor disposed near the winding for detecting the winding temperature of the motor by using electronic thermal relay technology. As the temperature sensor, a known temperature sensor can be used. The temperature sensor inside the motor is preferably disposed at a position where its temperature detection part is in contact with the winding, but it is sufficient as long as it is near the winding and can detect the winding temperature, and is not limited to a specific configuration.

[0017] Moreover, the processing device uses a calculation model including a winding temperature characteristic model and a specified temperature characteristic model to determine the two models in a manner capable of estimating the winding temperature during voltage application. The winding temperature characteristic model is a model for calculating the temperature characteristics of the winding when the thermal influence of the stator is hypothetically removed in the motor. Examples of the winding-related parameters included in this model can be the thermal resistance, thermal time constant, etc. related to the winding. In addition, the specified temperature characteristic model is a model for calculating the characteristics of the temperature detected by the temperature sensor when the thermal influence of the stator is hypothetically removed in the motor. It can be considered that the winding temperature is reflected in the detection of the temperature sensor. Examples of the specified parameters included in this model can be the thermal resistance, thermal time constant, etc. related to the temperature detection of the temperature sensor.

[0018] Here, the temperature change acquisition unit acquires two temperature changes (rising changes) associated with the winding in a state where a voltage is applied to raise the temperature of the winding to a specified temperature. One rising change is the temperature change actually generated in the winding, i.e., the first rising change, and the other rising change is the rising change in the detected temperature of the temperature sensor, i.e., the second rising change. Moreover, in order to estimate the winding temperature using a calculation model including a specified temperature characteristic model and a winding temperature characteristic model through an electronic thermal relay technique, it is necessary to appropriately consider the influence of the temperature change of the stator on the winding temperature.

[0019] Here, since the above-mentioned first rising change is the temperature change of the winding and the second rising change is the change in the detected temperature of the temperature sensor arranged near the winding, it can be considered that the temperature change of the stator of the motor, which can be regarded as substantially the same, affects both rising changes. This means that by using the first rising change and the second rising change, it is possible to estimate the winding temperature considering the influence of the temperature change of the stator using the electronic thermal relay technique. Therefore, in the above processing device, the determination unit calculates a specified parameter based on the second rising change and determines the specified temperature characteristic model, and calculates a winding-related parameter based on the first rising change and determines the winding temperature characteristic model. The calculation model including the specified temperature characteristic model and the winding temperature characteristic model determined in this way can appropriately reflect the influence of the temperature change of the stator in a manner that absorbs the delay in temperature detection included in the temperature sensor to estimate the winding temperature.

[0020] In the above processing device, it may also be that the determination unit calculates the specified parameter based on the second rising change using a stator temperature characteristic model to determine the specified temperature characteristic model. The stator temperature characteristic model includes stator-related parameters associated with the temperature characteristics of the stator and has a correlation with the winding temperature characteristic model and the specified temperature characteristic model. And the determination unit calculates the winding-related parameter based on the first rising change using this stator temperature characteristic model to determine the winding temperature characteristic model. The stator temperature characteristic model is a model for calculating the temperature characteristics of the stator when the thermal influence of the winding is hypothetically removed in the motor. As the stator-related parameters included in this model, examples can be given of the thermal resistance, thermal time constant, etc. related to the stator. By adopting such a structure, it is possible to determine the specified temperature characteristic model and the winding temperature characteristic model that appropriately reflect the influence of the temperature change of the stator.

[0021] In the above processing device, it may also be that the temperature change acquisition unit acquires the first rising change based on the resistance value of the winding. Thus, when determining the specified temperature characteristic model and the winding temperature characteristic model, it is possible to accurately measure the rising change in the winding temperature by a measurement method different from that of the temperature sensor.

[0022] In addition, the above-described processing device may further include: a frequency response acquisition unit that acquires the frequency response of the motor when the current flowing through the winding is output with the applied voltage applied to the winding as an input; and a resistance calculation unit that calculates the resistance value of the winding based on the frequency response. In this way, by focusing on the electrical characteristics of the winding and using its frequency response, it is possible to minimize the voltage applied to the winding for detecting the resistance value of the winding, suppress the change in the winding temperature caused by the application of this voltage, and accurately measure the resistance value of the winding.

[0023] In addition, in the above-described processing device, it may also be that a voltage application of a first cycle is performed during the voltage application, the resistance calculation unit calculates the resistance value of the winding during the voltage application based on the frequency response acquired by the frequency response acquisition unit in accordance with the output current of the motor when the voltage application of the first cycle is input, and the temperature change acquisition unit acquires the first rising change based on the resistance value of the winding calculated by the resistance calculation unit. With such a configuration, it is possible to suppress the change in the winding temperature and accurately measure the resistance value of the winding with respect to the measurement of the first rising change.

[0024] Furthermore, in the above-described processing device, it may also be that when the voltage application is performed, the rotor of the motor is rotationally driven at a prescribed constant speed. In the temperature detection by the temperature sensor, the detection unit of the temperature sensor has a strong tendency to detect the temperature of the nearby winding. On the other hand, when a voltage is applied to the winding to obtain the second rising change, if the applied current tends to flow through a certain phase of the windings constituting the motor (for example, a certain phase among the U, V, and W phases in the case of a three-phase AC motor), there may be a deviation in the temperature detection by the temperature sensor. Therefore, by rotating the rotor at a prescribed constant speed as described above, it is possible to make the applied current flow through the windings of the motor substantially uniformly, and appropriately obtain the second rising change.

[0025] In addition, to solve the above problems, the present disclosure can also be understood from the aspect of the method for determining the winding temperature calculation model. That is, the present disclosure is a method for determining a calculation model, which is a calculation model of an electronic thermal relay of a motor having a stator and a rotor wound with windings and is used to estimate the temperature of the windings. The calculation model includes: a winding temperature characteristic model, which includes winding-related parameters associated with the temperature characteristics of the windings; and a specified temperature characteristic model, which includes specified parameters associated with the characteristics of the temperature near the windings detected by a temperature sensor arranged near the windings. Moreover, the method includes the following steps: obtaining a first rising trend as the rising trend of the temperature of the windings in a state where a voltage is applied to raise the temperature of the windings to a specified temperature and a second rising trend as the rising trend of the detected temperature of the temperature sensor; and a determination step of calculating the specified parameters based on the second rising trend to determine the specified temperature characteristic model, and calculating the winding-related parameters based on the first rising trend to determine the winding temperature characteristic model. Alternatively, in the determination step, the specified parameters can be calculated based on the second rising trend with the help of a stator temperature characteristic model to determine the specified temperature characteristic model. The stator temperature characteristic model includes stator-related parameters associated with the temperature characteristics of the stator and is correlated with the winding temperature characteristic model and the specified temperature characteristic model, and the winding-related parameters can be calculated based on the first rising trend with the help of the stator temperature characteristic model to determine the winding temperature characteristic model. In addition, as long as there is no technical inconsistency, the technical idea disclosed by the above processing device can be applied to the method for determining the winding temperature calculation model.

[0026] Advantages of the Invention

[0027] Regarding the electronic thermal relay of the motor, the temperature of the windings can be accurately estimated. Description of the Drawings

[0028] Figure 1 Figure 1 is a diagram showing the structure of a calculation model including a winding temperature characteristic model and a specified temperature characteristic model.

[0029] Figure 2 Figure 2 The (A) of [] is a diagram for explaining the correlation between the winding temperature characteristic model and the stator temperature characteristic model, Figure 2 and the (B) of [] is a diagram for explaining the correlation between the specified temperature characteristic model and the stator temperature characteristic model.

[0030] Figure 3 Figure 3 ​​​​​​It is a diagram showing the change in the voltage applied to the motor when matching the calculation model with the motor, the winding temperature at this time, and the change in the detected temperature of the temperature sensor.

[0031] Figure 4 Figure 4 It is a schematic structure of a control system formed by assembling a motor.

[0032] Figure 5 Figure 5 It is shown by Figure 4 The first diagram showing the control structure formed by the servo drive of the control system.

[0033] Figure 6 Figure 6 It is shown by Figure 4 The second diagram showing the control structure formed by the servo drive of the control system.

[0034] Figure 7 Figure 7 It is a flowchart showing the processing flow of the matching method between the calculation model and the motor executed by the servo drive.

[0035] Figure 8 Figure 8 Of (A) and Figure 8 Of (B) is a diagram showing the change in the voltage applied to the motor. Detailed implementation mode

[0036] <Application example>

[0037] Based on Figures 1 to 3 An example of a processing device for adjusting model parameters for estimating the temperature of the motor winding by the electronic thermal relay in the motor 2 (refer to Figure 4 ) is described. In addition, in the embodiment of the present disclosure, the motor 2 only needs to have a structure in which windings are wound around its stator and has a rotor, and its specific structure is not limited to a specific structure. In addition, inside the motor 2, a temperature sensor 3 is arranged in a manner capable of detecting the temperature of its winding. More specifically, the detection part of the temperature sensor 3 is arranged near the winding, and preferably the detection part is arranged in contact with the winding.

[0038] Here, Figure 1 Represents the schematic structure of the calculation model 10 for calculating the winding temperature possessed by the electronic thermal relay of the motor. In addition, Figure 2 Of (A) and Figure 2 Of (B) are diagrams for explaining the derivation of the calculation model 10, showing the correlation between the winding temperature characteristic model and the stator temperature characteristic model, and the correlation between the specified temperature characteristic model and the stator temperature characteristic model. Moreover,​​​​​​​​​​Figure 3 This is a graph showing the voltage change of the motor and the change in the winding temperature at that time when determining Figure 1 the calculation parameters used in the calculation model 10 shown, that is, the winding-related parameters and the specified parameters.

[0039] Here, before explaining the calculation model 10, based on Figure 2 (A) of, a calculation model (hereinafter referred to as the "basic calculation model") 20 for estimating the temperature of the winding will be described, which can consider the main heat sources that may affect the winding temperature in the motor 2, that is, the winding and the stator, which are structures with relatively large heat capacities. The basic calculation model 20 is a program for calculating the winding temperature of the motor 2. When the applied power in the motor is provided as its input, the winding temperature of the motor is output. In addition, this applied power can be regarded as the so-called copper loss generated by the resistance of the winding coil of the motor, and is physically proportional to the square of the current flowing through the winding coil. And as Figure 1 shown, the basic calculation model 20 includes a winding temperature characteristic model 21 and a stator temperature characteristic model 22 as its constituent sub-models. The winding temperature characteristic model 21 is a model for calculating the temperature characteristics of the winding when the thermal influence of the stator is hypothetically removed in the motor, and the stator temperature characteristic model 22 is a model for calculating the temperature characteristics of the stator when the thermal influence of the winding is hypothetically removed in the motor. In this way, the basic calculation model 20 includes two models. Furthermore, as Figure 2 (A) of shows, the sum of the outputs of each model is calculated as the winding temperature of the motor, and thus it becomes a structure for calculating the winding temperature of the motor on the basis of considering the correlation between the stator and the winding.

[0040] Here, the winding temperature characteristic model 21 will be described. The winding temperature characteristic model 21 includes the thermal resistance Ra and the thermal time constant Ta related to the winding, which are parameters (winding-related parameters) associated with the temperature characteristics of the winding, and are represented by the following formula 1. In addition, the thermal resistance Ra is a value representing the difficulty of heat transfer, and is a parameter representing the temperature rise amount of the heat generated per unit time. In this embodiment, the thermal resistance when the winding of the motor is understood as a thermally uniform object is adopted. In addition, the thermal time constant Ta is a parameter representing the degree of responsiveness to the temperature change of the winding, and is defined as the time required for the temperature difference of the winding to change by 63.2% when the winding changes from the initial thermal equilibrium state to another thermal equilibrium state.

[0041] Winding temperature characteristic model = Ra / (Ta·s + 1) … (Formula 1)

[0042] Next, the stator temperature characteristic model 22 will be described. The stator temperature characteristic model 22 includes the thermal resistance Rb related to the stator and the thermal time constant Tb, which are parameters (stator-related parameters) associated with the temperature characteristics of the stator, and are represented by Equation 2 below. In addition, the definition of the thermal resistance Rb is the same as the definition of the thermal resistance Ra described above. In this embodiment, the thermal resistance when the stator of the motor is understood as a thermally uniform object is adopted. Additionally, the thermal time constant Tb is a parameter indicating the degree of responsiveness to the temperature change of the stator, and has the same definition as the thermal time constant Ta described above.

[0043] Stator temperature characteristic model = Rb / (Tb·s + 1) … (Equation 2)

[0044] Moreover, in the basic calculation model 20, the input (the applied power in the motor) is transmitted to the winding temperature characteristic model 21 and the stator temperature characteristic model 22. Then, the outputs of the respective models are added together as the output of the basic calculation model 20, that is, the estimated temperature of the motor winding. In addition, when adding the outputs of the respective models, it is also possible to add the values obtained by multiplying the outputs of the respective models by a prescribed gain. By configuring the basic calculation model 20 in this way, the winding temperature of the motor is estimated considering the correlation between the stator and the winding.

[0045] In the case of using the basic calculation model 20 to estimate the winding temperature in this way, it is necessary to determine the stator temperature characteristic model 22. However, in order to determine the stator temperature characteristic model 22, it is preferable to form a situation where the winding does not thermally affect the stator as much as possible, but this is not easy. Therefore, in the present application disclosure, the change in the detected temperature of the temperature sensor 3 disposed near the winding of the motor 2 is utilized. In Figure 2 (B) shows a calculation model (hereinafter referred to as the "near-winding calculation model") 30 that can estimate the temperature near the winding, that is, the detected temperature of the temperature sensor 3. The near-winding calculation model 30 is a program for calculating the detected temperature of the temperature sensor 3, and when the applied power in the motor 2 is provided as its input, it outputs the detected temperature of the temperature sensor 3. And, as Figure 2 (B) shows, the near-winding calculation model 30 includes a prescribed temperature characteristic model 31 and a stator temperature characteristic model 32 as sub-models that constitute itself.

[0046] The prescribed temperature characteristic model 31 is a model for calculating the detected temperature characteristic (temperature characteristic near the winding) of the temperature sensor 3 when the thermal influence of the stator is hypothetically removed in the motor, and it can be considered that the temperature characteristic of the winding is reflected in this detected temperature characteristic. In addition, the stator temperature characteristic model 32 is a model for calculating the temperature characteristic of the stator when the thermal influence of the winding is hypothetically removed in the motor. Therefore, it can be considered that the stator temperature characteristic model 32 is related to Figure 2is the same as the stator temperature characteristic model 22 shown in (A). Thus, the winding vicinity calculation model 30 includes two models, and as shown in Figure 2 of (B), it has a structure that calculates the sum of the outputs of each model as the detected temperature of the temperature sensor 3.

[0047] The specified temperature characteristic model 31 includes the thermal resistance Rs and the thermal time constant Ts as parameters (specified parameters) associated with the detected temperature of the temperature sensor 3, that is, the temperature characteristic in the vicinity of the winding, and is represented by Equation 3 below. In addition, the definition of the thermal resistance Rs is the same as the definition of the above-mentioned thermal resistance Ra. In this embodiment, the thermal resistance when the winding of the motor and the space around it are regarded as a thermally uniform object is adopted. Further, the thermal time constant Ts is a parameter indicating the degree of responsiveness to the temperature change of the space around the winding and its vicinity, and is the same as the definition of the above-mentioned thermal time constant Ta.

[0048] Specified temperature characteristic model = Rs / (Ts·s + 1)…(Equation 3)

[0049] The stator temperature characteristic model 32 can be regarded as the same as the stator temperature characteristic model 22 as described above, so its detailed description is omitted. And in the winding vicinity calculation model 30, the input (the applied power in the motor) is transmitted to the specified temperature characteristic model 31 and the stator temperature characteristic model 32. Then, the outputs of each model are added together as the output of the winding vicinity calculation model 30, that is, the estimated value of the detected temperature of the temperature sensor 3.

[0050] Here, if we compare Figure 2 of (A) and Figure 2 of (B), the stator temperature characteristic models 22 and 32 are commonly included in the basic calculation model 20 for estimating the winding temperature and the winding vicinity calculation model 30 for estimating the detected temperature of the temperature sensor 3. Therefore, by substituting the stator temperature characteristic model 32 derived from the winding vicinity calculation model 30 into the stator temperature characteristic model 22 included in the basic calculation model 20, the Figure 1 shown calculation model 10 can be derived.

[0051] Based on the above, the calculation model 10 of the electronic thermal relay will be described based on Figure 1 The calculation model 10 is a program for calculating the winding temperature of the motor in the electronic thermal relay of the motor. When the applied power in the motor is provided as its input, it outputs the winding temperature of the motor. And as shown in Figure 1 the calculation model 10 includes a winding temperature characteristic model 11, a specified temperature characteristic model 12, and the temperature sensor 3 as sub-models that constitute itself. The winding temperature characteristic model 11 is a model for calculating the temperature characteristic of the winding when the thermal influence of the stator is hypothetically removed in the motor, and is the same as Figure 2The temperature characteristic model 12 is the same as the winding temperature characteristic model 21 shown in (A) of FIG. 1. In addition, the temperature characteristic model 12 is a model for calculating the detection temperature characteristic (temperature characteristic near the winding) of the temperature sensor 3 when the heat effect of the stator is removed in the motor, and is the same as Figure 2 The same model as the prescribed temperature characteristic model 31 shown in (B).

[0052] In the calculation model 10 constructed in this way, Figure 1 The portion surrounded by the dotted line 15 is equivalent to Figure 2 The structure of the stator temperature characteristic model 32 shown in (B) of FIG. Therefore, when the input (the applied power in the motor) is transmitted to the winding temperature characteristic model 11 and the predetermined temperature characteristic model 12, the output of the winding temperature characteristic model 11 is added with the difference between the output of the temperature sensor 3 and the predetermined temperature characteristic model 12, and the output of the calculation model 10, that is, the estimated temperature of the motor winding, is used. In addition, when the outputs of the models are added, the values ​​obtained by multiplying the outputs of the models by the predetermined gain may be added.

[0053] Next, based on Figure 3 , the calculation of the thermal resistance Ra and the thermal time constant Ta used in the winding temperature characteristic models 11 and 21, the calculation of the thermal resistance Rs and the thermal time constant Ts used in the prescribed temperature characteristic models 12 and 31, and the calculation of the thermal resistance Rb and the thermal time constant Tb used in the stator temperature characteristic models 22 and 32 are explained. In addition, these parameters Ra, Rb, Rs, Ta, Tb, and Ts are also collectively referred to as model parameters.

[0054] exist Figure 3 In the transition of the applied voltage shown in the upper part of FIG. 1 , during the period from time T1 to T2, a voltage is applied to the motor 2 to increase the winding temperature to a predetermined temperature. During the period from time T1 to T2, the winding temperature of the motor is as follows: Figure 3rises and converges as shown by the line L1 in the lower part thereof (rise from temperature t0 to temperature t1), and thus the winding temperature transition during this period is referred to as the first rising transition L1. In addition, the actual detected temperature transition (rising from temperature t0 to temperature t2 and converging) of the temperature sensor 3 arranged to detect the temperature near the motor winding is represented by the line L2. Since there is some heat capacity between the winding and the temperature sensor 3, the second rising transition L2 is slightly on the lower temperature side compared to the first rising transition L1. In addition, when applying a voltage, the applied voltage V1 is such that the current flows only on the d-axis to prevent the rotor of the motor 2 from rotating. Thereby, it is possible to avoid the accidental driving of the drive shaft of the motor 2 during this voltage application. As another method, the voltage V1 may be applied such that the rotor of the motor 2 rotates at a prescribed low speed (e.g., several tens of rpm) when applying the voltage. Thereby, it is possible to make the current flow uniformly in the winding of the motor 2 and reduce the influence of the arrangement of the temperature sensor 3 on its detected temperature. In addition, the applied voltage V1 at this time may be an applied voltage that raises the motor temperature to be suitable for the calculation of the above model parameters, and for example, it can be set to a voltage corresponding to the rated power of the motor.

[0055] Moreover, the model parameters Ra, Rb, Rs, Ta, Tb, Ts are calculated based on the first rising transition L1 and the second rising transition L2 from time T1 to T2. First, based on the second rising transition L2, the thermal resistance Rs and the thermal time constant Ts associated with the prescribed temperature characteristic model 12, 31, and the thermal resistance Rb and the thermal time constant Tb associated with the stator temperature characteristic model 22, 32 are calculated. Specifically, using the least squares method, based on the time required for the detected temperature of the temperature sensor 3 to rise from t0 to t2, the input power, etc., the model parameters Rs, Ts, Rb, Tb are calculated. Thereby, the prescribed temperature characteristic model 12, 31 and the stator temperature characteristic model 22, 32 are determined. Next, based on the first rising transition L1, the thermal resistance Ra and the thermal time constant Ta associated with the winding temperature characteristic model 11, 21 are calculated. In addition, in this calculation, regarding the thermal resistance Rb and the thermal time constant Tb associated with the stator temperature characteristic model 22, 32, the already calculated values are used. The specific calculation of the winding temperature characteristic model 11, 21 is also performed using the least squares method, based on the time required for the detected temperature of the temperature sensor 3 to rise from t0 to t1, the input power, etc. Thereby, the winding temperature characteristic model 11, 21 is determined.

[0056] The calculated model parameters are used to form a winding temperature characteristic model 11 and a specified temperature characteristic model 12, and then a calculation model 10 including the two models is determined. By using the calculation model 10 thus determined, the winding temperature of the motor can be estimated by the electronic thermal relay using the detection value of the temperature sensor 3. In this estimation, since the winding temperature is calculated by the calculation model 10 in a form that absorbs the detection delay included in the temperature sensor 3, it is possible to achieve high-precision and low-delay estimation of the winding temperature. Therefore, overheating of the winding of the motor 2 can be effectively suppressed.

[0057] <First Embodiment>

[0058] Figure 4 It is a schematic structural diagram of a control system including a servo drive 4 that also operates as a processing device of the present embodiment. This control system includes a network 1, a motor 2, a servo drive 4, and a standard PLC (Programmable Logic Controller) 5. In addition, as described above, the motor 2 is provided with a temperature sensor 3. This control system is a system for driving and controlling a load device (not shown) together with the motor 2. And the motor 2 and the load device are set as control objects controlled by this control system. Here, as the load device, various mechanical devices (for example, the arm of an industrial robot, a handling device) can be exemplified. In addition, the motor 2 is assembled in the load device as an actuator for driving the load device. For example, the motor 2 is an AC servo motor having a stator with a wound winding and a rotor. In addition, an encoder (not shown) is installed in the motor 2, and parameter signals related to the operation of the motor 2 are feedback-transmitted to the servo drive 4 through this encoder. The feedback-transmitted parameter signals (hereinafter referred to as feedback signals) include, for example, position information about the rotational position (angle) of the rotation axis of the motor 2, information about the rotational speed of the rotation axis, and the like.

[0059] The servo drive 4 receives, via the network 1, an operation instruction signal related to the motion of the motor 2 from the standard PLC 5, and also receives a feedback signal output from the encoder connected to the motor 2. Based on the operation instruction signal from the standard PLC 5 and the feedback signal from the encoder, the servo drive 4 calculates a servo control related to the drive of the motor 2, that is, an instruction value related to the motion of the motor 2, and supplies a drive current to the motor 2 in such a manner that the motion of the motor 2 follows the instruction value. In addition, the supplied current uses the AC power transmitted from the AC power supply 7 to the servo drive 4. In the present embodiment, the servo drive 4 is of the type that accepts three-phase alternating current, but it may also be of the type that accepts single-phase alternating current. In addition, the servo control of the servo drive 4 is a feedback control using the position controller 41, speed controller 42, and current controller 43 provided in the servo drive 4, and the detailed content will be based on Figure 5 described later.

[0060] Here, as Figure 4 shown, the servo drive 4 includes a position controller 41, a speed controller 42, and a current controller 43, and performs the above-described servo control through these processes. Moreover, the servo drive 4 has an electronic thermal relay unit 100 (see Figure 5 ) in order to protect the motor 2 from damage caused by overloading. The electronic thermal relay unit 100 estimates the winding temperature of the motor 2 and determines the overload state of the motor 2 based on the estimated temperature. Therefore, based on Figure 5 the control structure formed in the servo drive 4 shown, the above-described servo control of the servo drive 4 and the protection control of the motor 2 by the electronic thermal relay unit 100 are described. This control structure is formed by executing a prescribed control program in the servo drive 4 having a prescribed arithmetic device and memory, etc.

[0061] The position controller 41 performs, for example, proportional control (P control). Specifically, a speed command is calculated by multiplying the position deviation, which is the deviation between the position command notified from the standard PLC 5 and the detected position, by the position proportional gain Kpp. In addition, the position controller 41 preliminarily has the position proportional gain Kpp as a control parameter. Next, the speed controller 42 performs, for example, proportional-integral control (PI control). Specifically, the integral of the speed deviation, which is the deviation between the speed command calculated by the position controller 41 and the detected speed, is multiplied by the speed integral gain Kvi, and the sum of the calculation result and the speed deviation is multiplied by the speed proportional gain Kvp, thereby calculating a torque command. In addition, the speed controller 42 preliminarily has the speed integral gain Kvi and the speed proportional gain Kvp as control parameters. In addition, the speed controller 42 may perform P control instead of PI control. In this case, the speed controller 42 preliminarily has the speed proportional gain Kvp as a control parameter. Next, the current controller 43 generates a command voltage for driving the amplifier 44 based on the torque command calculated by the speed controller 42. The amplifier 44 outputs a drive current for driving the motor 2 according to the generated command voltage, thereby performing drive control on the motor 2. The current controller 43 includes a filter related to the torque command (a first-order low-pass filter) and one or more notch filters, and has a cut-off frequency and the like related to the performance of these filters as control parameters.

[0062] Moreover, the control structure of the servo drive 4 includes a speed feedback system with the speed controller 42, the current controller 43, the motor 2 to be controlled, etc. as forward elements, and further includes a position feedback system with this speed feedback system and the position controller 41 as forward elements. With the control structure configured in this way, the servo drive 4 can perform servo control on the motor 2 in a manner that follows the position command supplied from the standard PLC 5.

[0063] When performing servo control on the motor 2 in this way, if an excessive load (for example, a load exceeding the rated load of the motor 2) is applied to the motor 2 for a relatively long time, an excessive current will flow through the winding of the motor 2 for a long time, so the winding temperature will rise excessively, which may cause its burnout. To avoid driving the motor 2 in an overloaded state, the servo drive 4 has an electronic thermal relay unit 100. Specifically, the electronic thermal relay unit 100 has Figure 1The calculation model 10 and the overload determination unit 110 shown above. As described above, the calculation model 10 includes a winding temperature characteristic model 11 and a specified temperature characteristic model 12. If the applied power of the motor 2 is provided as an input to each model and the detection value of the temperature sensor 3 is provided, the result outputs the winding temperature of the motor 2. And, based on the winding temperature that is the output of the calculation model 10, the overload determination unit 110 determines whether there is a possibility that the motor 2 reaches an overload state, in other words, whether there is a possibility that the winding of the motor 2 overheats. In addition, when it is determined by the overload determination unit 110 that the motor 2 is in an overload state, the servo drive 4 can stop its drive to protect the motor 2.

[0064] Here, based on Figure 6 A control structure for matching the calculation model 10 included in the electronic thermal relay unit 100 with the motor 2 that is the control object of the servo drive 4 will be described. The servo drive 4 has a model matching unit 200 in order to match the calculation model 10 with the motor 2. The model matching unit 200 calculates the model parameters of the calculation model 10 corresponding to the motor 2, that is, the thermal resistance Ra and the thermal time constant Ta of the winding temperature characteristic model 11 corresponding to the motor 2 and the thermal resistance Rs and the thermal time constant Ts of the specified temperature characteristic model 12, and uses them to match the calculation model 10 with the motor 2. In addition, when matching the calculation model 10, the Figure 5 shown current controller 43 and amplifier 44 are used, but the position controller 41 and the speed controller 42 are not used, so in Figure 6 the description of the position controller 41 and the speed controller 42 is omitted.

[0065] Here, the model matching unit 200 has an application control unit 210, a temperature change acquisition unit 220, and a determination unit 230. The application control unit 210 outputs an instruction for applying a voltage for calculating the model parameters of the calculation model 10 to the current controller 43, that is, Figure 3 the voltage application shown in the upper part of

[0066] The temperature change acquisition unit 220 obtains the first rise trend L1 and the second rise trend L2 of the winding temperature at the time of matching (voltage application) of the calculation model 10 based on the winding resistance value of the motor 2. The acquisition of this winding temperature is performed according to Equation 4 below.

[0067] Winding temperature θ2 = R2 / R1·(234.5 + θ1) - 234.5…(Equation 4)

[0068] R1 is the winding resistance value at the start of voltage application ( Figure 3 the moment T1 in

[0069] θ1 is the winding temperature at the start of voltage application. For example, the atmospheric temperature of the surrounding environment of the motor 2 (when it can be obtained by the servo drive 4) or the detection value of the temperature sensor provided in the encoder attached to the motor 2 can be used as θ1.

[0070] R2 is the winding resistance value when voltage is applied. In addition, the acquisition of the winding resistance value R2 will be described later.

[0071] The temperature change acquisition unit 220 acquires the winding temperature of the motor 2 at this time at any time according to Equation 4 as the voltage application by the application control unit 210 progresses.

[0072] Based on the first rising trend L1 and the second rising trend L2 acquired by the temperature change acquisition unit 220, the determination unit 230 calculates the thermal resistance Ra and the thermal time constant Ta of the winding temperature characteristic model 11 corresponding to the motor 2, and the thermal resistance Rs and the thermal time constant Ts of the specified temperature characteristic model 12. The calculation of these model parameters is as described above. Furthermore, the determination unit 230 applies the calculated model parameters to the winding temperature characteristic model 11 and the specified temperature characteristic model 12 of the calculation model 10 to determine each model. As a result, the Figure 1 calculation model 10 of the electronic thermal relay unit 100 shown matches the motor 2 itself controlled by the servo drive 4.

[0073] Here, based on Figure 7 a method for the model matching unit 200 to match the calculation model 10 will be described. Figure 7 is a flowchart showing the process of the method for the model matching unit 200 to match the calculation model 10. First, in S101, immediately before starting the voltage application by the application control unit 210, an initialization process for acquiring the winding resistance value (R1 in Equation 4) of the motor 2 and its winding temperature (θ1 in Equation 4) is performed. The winding resistance value is calculated based on the current value when a measurement voltage is applied between the terminals of the motor. In addition, regarding the winding temperature in this initialization process, when the motor 2 has been placed in the surrounding environment for a sufficient long time, it can be considered that this winding temperature is at the same level as the external air temperature. Therefore, the external air temperature or the detection temperature of the temperature sensor provided in the encoder of the motor 2 is acquired as the winding temperature in the initialization process.

[0074] Next, in S102, while applying a voltage by the application control unit 210, the first rising trend L1 of the winding temperature of the motor 2 and the second rising trend L2 of the detected temperature of the temperature sensor 3 are obtained by the temperature change obtaining unit 220. These rising trends share the voltage application period. Here, when the winding temperature rises due to this voltage application, if a voltage application for resistance value calculation is additionally performed, the temperature rise control based on the original voltage application will be hindered. In the voltage application for model parameter calculation, it is necessary to raise the winding temperature of the motor 2 to t1. Therefore, if its temperature rise is disrupted every time the resistance value is calculated, it will be difficult to appropriately calculate the model parameters (thermal resistance, thermal time constant). Therefore, in the present embodiment, a periodic voltage application is performed in the voltage application for model parameter calculation. While raising the winding temperature through this voltage application, when this voltage application is used as the input to the motor 2 and the current flowing through its winding is used as the output, the frequency response of the current with respect to this voltage application is used to calculate the winding resistance value of the motor 2.

[0075] Specifically, as shown in (A) of Figure 8 , during the voltage application, a periodic sine wave voltage is applied during the application period (T1 to T2). At this time, the effective value (root mean square value) of this sine wave voltage becomes the voltage V1 shown in Figure 3 . By applying such a periodic sine wave voltage in this way, the winding temperature of the motor 2 can be raised to t1. Here, when performing the periodic voltage application, the application voltage value and the current value flowing through the winding of the motor 2 are respectively obtained by the temperature change obtaining unit 220 as input values and output values. The frequency response of the output value with respect to this input value reflects the electrical characteristics of the motor 2 shown in the following formula 5.

[0076] Electrical characteristics of the motor 2: (1 / R)·(1 / (Ts + 1))... (Formula 5)

[0077] Among them, R is the winding resistance of the motor 2, and T is the electrical time constant of the motor 2.

[0078] Therefore, the temperature change obtaining unit 220 calculates the frequency response of the above output value, uses the gain G(ω) and phase P(ω) obtained based on this frequency response, and further calculates the winding resistance R of the motor 2 according to the following formula 6.

[0079]

[0080] Furthermore, the temperature change obtaining unit 220 substitutes the winding resistance R calculated by formula 6 into R2 in formula 4, and calculates the winding temperature (θ2 in formula 4) at the moment when the frequency response is obtained.

[0081] In this way, the temperature change obtaining unit 220 can obtain the first rising change L1 and the second rising change L2 by using the winding resistance value of the motor 2 without hindering the temperature rising process of the motor 2 (the process of raising the winding temperature to t1 and the process of raising the detected temperature of the sensor 3 to t2) by utilizing the frequency response of the current flowing through the winding of the motor 2 when a voltage is applied. In addition, the acquisition timing of each rising change of the temperature change obtaining unit 220, that is, the acquisition timing of the above frequency response, can be appropriately set within the range where each rising change can be obtained to the extent that the model parameters can be calculated.

[0082] In addition, in Figure 8 the example shown in (A) of Figure 8 , a sine wave voltage is continuously applied during the application period. However, as another method, as shown in (B) of

[0083] , as long as the winding temperature of the motor 2 can converge to the equilibrium state of t1, the sine wave voltage may be applied intermittently. At this time, the root mean square value of the intermittent sine wave voltage during the application period is the voltage V1. In addition, the period of the applied voltage during voltage application can be appropriately determined within the range where an appropriate frequency response is obtained for calculating the winding resistance value. If the period of the applied voltage becomes too long, the winding temperature is likely to change suddenly due to the voltage application. On the other hand, if the period of the applied voltage becomes too short, it is difficult to appropriately reflect the electrical characteristics of the motor 2 in the frequency response. Therefore, the frequency of the applied sine wave voltage is set, for example, to 1 / 3 to 3 times the frequency corresponding to the reciprocal of the electrical time constant of the motor 2, preferably set to 1 / 2 to 2 times, and more preferably set to the same frequency. Thereby, the temperature adjustment and temperature acquisition of the motor 2 can be achieved in a balanced manner.

[0083] Next, in S103, it is determined whether a prescribed voltage application time suitable for the calculation of the model parameters has elapsed. As an example, the prescribed voltage application time may be the application time until the winding temperature of the motor 2 converges to t1. When the rising change rate of the winding temperature of the motor 2 is equal to or less than a prescribed threshold value, it can be determined that the rise has converged. In addition, the rising change rate is defined as the amount of rise of the winding temperature per unit time. In addition, this threshold value may be a predetermined fixed value. As another method, the rising change rate of the winding temperature immediately after the start of voltage application, that is, the rising change rate when it is considered that the rising change rate is the highest during the application period, may be used as a reference to determine, for example, a value of 1 / 10 of the rising change rate considered to be the maximum may be used as this threshold value. If an affirmative determination is made in S103, the process proceeds to S104. If a negative determination is made, the processes after S102 are repeated to continue the voltage application.

[0084] Next, in S104, as based on Figures 1 to 3As described above, based on the second rising transition L2 obtained in S102, the thermal resistance Rb and the thermal time constant Tb, which are model parameters of the stator temperature characteristic models 22 and 32, and the thermal resistance Rs and the thermal time constant Ts, which are model parameters of the specified temperature characteristic models 12 and 31, are calculated, and each model is determined. Further, in S105, based on the first rising transition L1 obtained in S102, the thermal resistance Ra and the thermal time constant Ta, which are model parameters of the winding temperature characteristic models 11 and 21, are calculated, and the model is determined.

[0085] Thus, according to Figure 7 the calculation model matching method shown, an appropriate calculation model 10 that matches the motor 2 driven by the servo drive 4 can be prepared. Thereby, when the motor 2 is driven, it is possible to appropriately suppress the detection delay of the temperature sensor 3 while accurately estimating the winding temperature of the motor 2 by the electronic thermal relay unit 100, and it is possible to appropriately protect the motor 2 from the influence of overloading.

[0086] <Other Embodiments>

[0087] In the embodiments described above, the model matching unit 200 is formed in the servo drive 4, but instead of this method, it may be formed in a processing device (such as a PC (personal computer), etc.) that can be electrically connected to the servo drive 4. This processing device is a device for matching the calculation model with the motor 2 and is equipped with matching software (program). Specifically, this processing device is a computer having an arithmetic device, a memory, etc., and a program that can be executed by this computer is installed, and the calculation model matching method described is implemented by executing this program. Figure 7 the calculation model matching method described.

[0088] Regarding the dimensions, materials, shapes, their relative arrangements, the order of each process included in the method described, etc. of the structure described in the above-described embodiment, unless otherwise specifically described, it does not mean that the technical scope of the invention is limited thereto.

[0089] <Supplementary Note>

[0090] A processing device (4) that determines a calculation model (10), the calculation model (10) being a calculation model (10) of an electronic thermal relay (100) of a motor (2) having a stator wound with windings and a rotor, and being used to estimate the temperature of the windings, and including: a winding temperature characteristic model (11) that includes winding-related parameters associated with the temperature characteristics of the windings; and a specified temperature characteristic model (12) that includes specified parameters associated with the characteristics of the temperature near the windings detected by a temperature sensor (3) disposed near the windings, the processing device (4) includes:

[0091] A temperature change acquisition unit (220) that acquires a first increase trend (L1) of the temperature of the winding as an increase trend of the temperature of the winding in a state where a voltage is applied to raise the temperature of the winding to a specified temperature, and a second increase trend (L2) of the detected temperature of the temperature sensor as an increase trend of the detected temperature; and

[0092] A determination unit (230) that calculates the specified parameter based on the second increase trend (L2) to determine the specified temperature characteristic model (12), and calculates the winding-related parameter based on the first increase trend (L1) to determine the winding temperature characteristic model (11).

[0093] A method for determining a winding temperature calculation model, which is a method for determining a calculation model (10). The calculation model (10) is a calculation model (10) of an electronic thermal relay (100) of a motor (2) having a stator with a winding wound thereon and a rotor, and is used to estimate the temperature of the winding. The method includes: a winding temperature characteristic model (11), which includes a winding-related parameter associated with the temperature characteristic of the winding; and a specified temperature characteristic model (12), which includes a specified parameter associated with the characteristic of the temperature near the winding detected by a temperature sensor (3) disposed near the winding. The method for determining the winding temperature calculation model includes the following steps:

[0094] A step (S102) of acquiring a first increase trend (L1) of the temperature of the winding as an increase trend of the temperature of the winding in a state where a voltage is applied to raise the temperature of the winding to a specified temperature, and a second increase trend (L2) of the detected temperature of the temperature sensor as an increase trend of the detected temperature; and

[0095] A step (S104, S105) of calculating the specified parameter based on the second increase trend (L2) to determine the specified temperature characteristic model (12), and calculating the winding-related parameter based on the first increase trend (L1) to determine the winding temperature characteristic model (11).

[0096] Reference Numeral Explanation

[0097] 2: Motor; 3: Temperature sensor; 4: Servo driver; 10: Calculation model; 11: Winding temperature characteristic model; 12: Specified temperature characteristic model; 100: Electronic thermal relay unit; 200: Model matching unit; 210: Application control unit; 220: Temperature change acquisition unit; 230: Determination unit.

Claims

1. A processing device determines a calculation model, which is a calculation model of an electronic thermal relay of a motor having a stator with a winding wound around it and a rotor, for estimating the temperature of the winding. The calculation model includes: a winding temperature characteristic model, which includes winding-related parameters associated with the temperature characteristics of the winding; and a specified temperature characteristic model including specified parameters associated with the characteristics of the temperature near the winding detected by a temperature sensor disposed near the winding, the processing device including: a temperature change acquisition unit that acquires a first change in the temperature of the winding as the temperature of the winding rises and a second change in the detected temperature of the temperature sensor in a state where a voltage is applied to raise the temperature of the winding to a specified temperature; and a determination unit that calculates the specified parameters based on the second change to determine the specified temperature characteristic model, and calculates the winding-related parameters based on the first change to determine the winding temperature characteristic model, the determination unit calculates the specified parameters based on the second change by means of a stator temperature characteristic model to determine the specified temperature characteristic model, the stator temperature characteristic model including stator-related parameters associated with the temperature characteristics of the stator and being correlated with the winding temperature characteristic model and the specified temperature characteristic model, and the determination unit calculates the winding-related parameters based on the first change by means of the stator temperature characteristic model to determine the winding temperature characteristic model.

2. The processing device according to claim 1, wherein the temperature change acquisition unit acquires the first change based on the resistance value of the winding.

3. The processing device according to claim 2, wherein the processing device further includes: a frequency response acquisition unit that acquires the frequency response of the motor when an applied voltage applied to the winding is input and a current flowing through the winding is output; and a resistance calculation unit that calculates the resistance value of the winding based on the frequency response.

4. The processing device according to claim 3, wherein a voltage application in a first period is performed during the voltage application, the resistance calculation unit calculates the resistance value of the winding during the voltage application based on the frequency response acquired by the frequency response acquisition unit in accordance with the output current of the motor when the voltage application in the first period is input, the temperature change acquisition unit acquires the first change based on the resistance value of the winding calculated by the resistance calculation unit.

5. The processing device according to any one of claims 1 to 4, wherein when the voltage is applied, the rotor of the motor is rotationally driven at a specified constant speed.

6. A method for determining a winding temperature calculation model, which is a method for determining a calculation model. The calculation model is a calculation model for estimating the temperature of a winding of an electronic thermal relay of a motor having a stator and a rotor with the winding wound thereon. The calculation model includes: a winding temperature characteristic model, which includes winding-related parameters associated with the temperature characteristics of the winding; and a specified temperature characteristic model including specified parameters associated with the characteristics of the temperature near the winding detected by a temperature sensor disposed near the winding, the method for determining the winding temperature calculation model including the following steps: acquiring a first change in the temperature of the winding as the temperature of the winding rises and a second change in the detected temperature of the temperature sensor in a state where a voltage is applied to raise the temperature of the winding to a specified temperature; and Determination step: Based on the second rising transition, calculate the specified parameter to determine the specified temperature characteristic model, and based on the first rising transition, calculate the winding-related parameter to determine the winding temperature characteristic model. In the determination step, based on the second rising transition, calculate the specified parameter by means of the stator temperature characteristic model to determine the specified temperature characteristic model. The stator temperature characteristic model includes stator-related parameters associated with the temperature characteristic of the stator and is correlated with the winding temperature characteristic model and the specified temperature characteristic model. And in the determination step, based on the first rising transition, calculate the winding-related parameter by means of the stator temperature characteristic model to determine the winding temperature characteristic model.

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