JP7534170B2 - Temperature detection device for detecting motor temperature and motor drive device - Google Patents

Description

The present invention relates to a temperature detection device that detects the temperature of a motor and a motor drive device.

When an excessive load is placed on a motor installed in a machine tool or robot, or when an abnormal high-frequency current flows through the windings inside the motor, the motor will heat up. Furthermore, if the performance of a cooling device installed near the motor is insufficient, the heat generated by the motor cannot be suppressed. When a motor generates excessive heat, thermal demagnetization occurs in the magnets inside the motor, and the windings inside the motor can burn out. For this reason, motor temperature information is obtained by a temperature detection device via a temperature detection element installed near the motor, and various measures are taken to deal with excessive heat generated by the motor based on this temperature information.

Temperature detection elements include elements such as thermistors and resistance thermometers, whose resistance value between two electrode terminals changes depending on temperature. In this specification, a temperature detection element refers to an element whose resistance changes depending on temperature. When a current flows through the two electrode terminals of a temperature detection element, a voltage corresponding to the resistance value is generated between the two electrode terminals. The change in the voltage value between the two electrode terminals is in other words a change in the resistance value. There is a certain relationship between the sensed temperature and output voltage of a temperature detection element, and a temperature detection device connected to the temperature detection element uses this relationship to obtain temperature information from the output voltage of the temperature detection element.

For example, an electric motor device is known that includes an electric motor and a control device that controls the electric motor. The control device includes a current detection means that determines the current to be passed through the excitation coil, a coil temperature estimation means that calculates estimated temperatures of multiple regions of the excitation coil from the current of the excitation coil determined by the current detection means and information including the heat generation and heat dissipation characteristics of the excitation coil, and a temperature distribution estimation means that estimates the temperature distribution or local maximum temperature of multiple regions of the excitation coil based on a comparison result between the temperature of the excitation coil detected by the temperature detection element and the estimated temperature of the region closest to the temperature detection element among the estimated temperatures of the multiple regions estimated by the coil temperature estimation means (see, for example, Patent Document 1).

For example, a method for correcting a temperature sensor that is detachably attached to a wearable thermometer that performs wireless data communication and that senses the body temperature of a target object to measure the temperature is known, which includes an original resistance value acquisition process for sampling an original resistance value for each temperature sensor and acquiring the original resistance value, a calculation process for calculating a correction coefficient for correcting the temperature based on the difference between the acquired original resistance value and the resistance value measured by a standard thermometer, a storage process for storing the correction coefficient in a storage medium of the measuring device, and a process for transmitting the correction coefficient to the thermometer body (see, for example, Patent Document 2).

For example, a printed circuit board is known that includes an insulating substrate on which multiple pattern wiring is formed, multiple electronic components mounted on the surface of the insulating substrate, multiple temperature detection elements each attached to the surface or inside of the insulating substrate and whose electrical characteristics change depending on the temperature of the insulating substrate at the attachment point, and a control chip mounted on the surface of the insulating substrate and connected to each of the temperature detection elements via dedicated pattern wiring and capable of detecting the electrical characteristics of each of the temperature detection elements, the control chip being configured to estimate which of the multiple electronic components is a heat source based on the temperature distribution of the insulating substrate obtained from the electrical characteristics of each of the temperature detection elements (see, for example, Patent Document 3).

For example, there is known an internal combustion engine control device equipped with a control unit that controls the operating state of an internal combustion engine mounted on an internal combustion engine mounting body, in which the control unit acquires the ambient temperature of the internal combustion engine, acquires an injector temperature, which is the temperature of the injector, from the resistance value of the injector of the internal combustion engine, calculates an intake air temperature rise of the internal combustion engine from the ambient temperature and the injector temperature, and calculates the intake air temperature of the internal combustion engine by adding the intake air temperature rise to the ambient temperature (see, for example, Patent Document 4).

JP 2017-058131 A International Publication No. 2019/026323 JP 2015-046496 A JP 2018-053743 A

The output voltage of the temperature detection element is measured by a voltage measurement circuit in the temperature detection device that is connected to the temperature detection element. The voltage measurement circuit includes a resistor connected to one of the two electrode terminals of the temperature detection element, an operational amplifier that amplifies the difference between the signals output from the two electrode terminals of the temperature detection element to an appropriate signal level, and an analog-to-digital conversion unit that converts the analog signal output from the operational amplifier into a digital signal.

Temperature detection elements that are installed near the motor include, for example, PTC thermistors, NTC thermistors, and platinum resistance temperature detectors. The change in output voltage that accompanies a change in temperature of the temperature detection element varies depending on the type of element. For this reason, a voltage measurement circuit must be prepared for each type of temperature detection element, which is inefficient.

On the other hand, it is more efficient if one voltage measurement circuit can detect the output voltages of more types of temperature detection elements. In order to enable one voltage measurement circuit to detect the output voltages of more types of temperature detection elements, it is necessary to widen the dynamic range of the voltage that the voltage measurement circuit can measure. However, if the dynamic range of the voltage that the voltage measurement circuit can measure is wide, depending on the characteristics of the temperature detection element, the amount of voltage change relative to the dynamic range may become small, resulting in a problem of reduced temperature detection resolution.

In addition, each component, such as a resistor, an operational amplifier, and an analog-digital converter, that constitutes a voltage measurement circuit that measures the voltage value of a temperature detection element has individual variations in the characteristics of the component and variations in characteristics over time. For this reason, even if multiple voltage measurement circuits of the same specification are manufactured using the same types of components, variations in the measurement accuracy of each voltage measurement circuit occur, and the variations also increase over time. Such variations in the characteristics of each component that constitutes a voltage measurement circuit make the problem of reduced resolution of temperature detection that occurs when attempting to detect the output voltage of more types of temperature detection elements with the above-mentioned single voltage measurement circuit more pronounced. Therefore, it is desirable to realize a temperature detection device and a motor drive device that can accurately detect temperature without being affected by the variations in the characteristics of each component that constitutes a circuit that measures the output voltage of a temperature detection element.

According to one aspect of the present disclosure, a temperature detection device includes a measurement unit that measures a voltage output through two electrode terminals of a temperature detection element, the resistance value between which changes in response to a change in temperature; an acquisition unit that acquires temperature information from the voltage measured by the measurement unit in accordance with a table that defines a temperature-voltage characteristic that shows the relationship between the sensed temperature of the temperature detection element and the output voltage; a correction unit that corrects the acquisition process by the acquisition unit using a set correction amount and causes the acquisition unit to output the corrected temperature information; and a setting unit that sets the correction amount in response to the voltage measured by the measurement unit in a setting mode , wherein the measurement unit has a first voltage dividing resistor connected in series to the temperature detection element via one of the two electrode terminals, and a second voltage dividing resistor connected in series to the first voltage dividing resistor and connected in parallel to the temperature detection element via the two electrode terminals, and the setting unit sets the correction amount in the setting mode in response to the voltage appearing across the second voltage dividing resistor measured by the measurement unit when the temperature detection element is detached from the measurement unit .

According to one aspect of the present disclosure, the motor drive device includes a motor control unit that controls the drive of the motor, and the above-mentioned temperature detection device, and the temperature detection device obtains corrected temperature information based on the voltage output through two electrode terminals of a temperature detection element provided near the motor.

According to one aspect of the present disclosure, it is possible to realize a temperature detection device and a motor drive device that can accurately detect temperature without being affected by variations in the characteristics of each component that constitutes a circuit that measures the output voltage of a temperature detection element.

1 is a diagram illustrating a temperature detection device and a motor drive device including the same according to an embodiment of the present disclosure. 1A and 1B are diagrams showing a first form of a measurement unit in a temperature detection device according to one embodiment of the present disclosure, in which (A) shows the connection relationship between the measurement unit and the temperature detection element in a normal mode, and (B) shows the connection relationship between the measurement unit and the temperature detection element in a setting mode. 1A and 1B are diagrams showing a second form of a measurement unit in a temperature detection device according to one embodiment of the present disclosure, in which (A) shows the connection relationship between the measurement unit and the temperature detection element in normal mode, and (B) shows the connection relationship between the measurement unit and the temperature detection element in setting mode. 1 is a diagram illustrating an example of temperature-resistance characteristic showing the relationship between the sensed temperature and the resistance value of a temperature detection element. 1 is a diagram illustrating a temperature-voltage characteristic showing the relationship between the sensed temperature of a temperature detection element and the output voltage. 1A to 1C are diagrams illustrating a first mode of correction processing in a temperature detection device and a motor drive device including the same according to an embodiment of the present disclosure. FIG. 11 is a diagram illustrating temperature-voltage characteristics corresponding to a plurality of different correction amounts.

The temperature detection device that detects the temperature of a motor and the motor drive device will be described below with reference to the drawings. The scale of these drawings has been appropriately changed to facilitate understanding. The form shown in the drawings is one example for carrying out the invention, and the invention is not limited to the illustrated embodiment.

Figure 1 shows a temperature detection device according to one embodiment of the present disclosure and a motor drive device equipped with the same.

The temperature detection device 1 according to an embodiment of the present disclosure detects the temperature of the motor 200 via a temperature detection element 300 provided near the motor 200. The temperature detection element 300 is an element in which the resistance value between two electrode terminals changes in response to temperature changes. Examples of the temperature detection element 300 include a PTC thermistor, an NTC thermistor, and a platinum resistance temperature detector. The temperature detection element 300 may be installed near a part of the motor 200 that is prone to heat generation, such as the iron core or windings. Alternatively, the temperature detection element 300 may be installed near a cooling device provided near the motor 200 in order to check the operating status of the cooling device.

The motor drive device 100 according to one embodiment of the present disclosure includes a temperature detection device 1, a motor control unit 2, and a higher-level control unit 3. The motor drive device 100 also includes a display unit 4 as an option.

The upper control unit 3 generates a drive command for controlling the speed, torque, or rotor position of the motor 200 based on the speed of the motor 200 (speed feedback), the current flowing through the windings of the motor 200 (current feedback), a predetermined torque command, and the operation program of the motor 200, and transmits it to the motor control unit 2. The upper control unit 3 also receives temperature information detected by the temperature detection device 1. The upper control unit 3 converts the received temperature information into display data for display on the display unit 4, and transmits it to the display unit 4. The upper control unit 3 may also use the received temperature information, for example, in the process of generating a drive command, or in other processes.

The display unit 4 displays the temperature of the motor 200 based on the display data received from the upper control unit 3. Examples of the display unit 4 include a standalone display device, a display device attached to the upper control unit 3, a display device attached to the motor control unit 2, a display device attached to the motor drive device 100, and a display device attached to a personal computer or a mobile terminal. Alternatively, instead of the display unit 4, the temperature information detected by the temperature detection device 1 may be output by an audio device that emits a sound such as a voice, a speaker, a buzzer, or a chime. This allows the worker to quickly and reliably grasp the temperature of the motor 200. This makes it easy for the worker to take action such as, for example, emergency stopping the motor drive device 100 or replacing or repairing the motor 200.

The motor control unit 2 controls the driving of the motor 200 by generating driving power for the motor 200 based on the driving command received from the upper control unit 3. For this reason, the motor control unit 2 includes a main power conversion circuit (not shown) for generating driving power for the motor 200 and a control circuit (not shown) for controlling the power generation process of the main power conversion circuit. For example, when the motor 200 is an AC motor, the main power conversion circuit in the motor control unit 2 is composed of a rectifier that converts AC power supplied from an AC power source into DC power and an inverter that converts the DC power into AC power and supplies the AC driving power to the motor 200. Alternatively, the main power conversion circuit in the motor control unit 2 is composed of an inverter that converts DC power supplied from a battery into AC power and supplies the AC driving power to the motor 200. Furthermore, when the motor 200 is a DC motor, the main power conversion circuit in the motor control unit 2 is composed of, for example, a rectifier that converts AC power supplied from an AC power source into DC power and supplies the DC drive current to the motor 200, and a DCDC converter that converts the DC voltage applied from a battery into an appropriate DC voltage and supplies the DC drive current to the motor 200. Note that the configuration of the motor control unit 2 defined here is merely an example, and the configuration of the motor control unit 2 may be defined to include terms such as power source and battery. Also, for example, the control circuit in the motor control unit 2 may be configured as an integral part of the upper control unit 3.

The temperature detection device 1 according to one embodiment of the present disclosure includes a measurement unit 11, an acquisition unit 12, a correction unit 13, and a setting unit 14.

The two electrode terminals of the temperature detection element 300 are connected to the input terminal of the measurement unit 11. The measurement unit 11 measures the voltage output through the two electrode terminals of the temperature detection element 300. Data on the voltage measured by the measurement unit 11 is sent to the acquisition unit 12 in a normal mode other than the setting mode, and is sent to the setting unit 14 in the setting mode. The "setting mode" refers to a mode in which a correction amount corresponding to the voltage output through the two electrode terminals of the temperature detection element 300 is set. The "normal mode" refers to a mode in which the temperature detection device 1 to which the temperature detection element 300 is connected detects temperature information through the temperature detection element 300.

The setting unit 14 has a receiving unit 31 that receives a setting start command, which is, for example, a command to start the setting mode, and when the receiving unit 31 receives the setting start command, it starts the process of setting the correction amount. The setting unit 14 sets the correction amount according to the voltage measured by the measuring unit 11 in the setting mode. Data on the correction amount set by the setting unit 14 is sent to the correction unit 13. The setting start command may be automatically input to the receiving unit 31 of the setting unit 14 when the motor driving device 100 or the temperature detection device 1 is powered on. Alternatively, the setting start command may be input to the receiving unit 31 of the setting unit 14 by, for example, an operator operating an input device (not shown) connected to the temperature detection device. The input device may be a standalone input device, an input device attached to the upper control unit 3, an input device attached to the motor control unit 2, an input device attached to the motor driving device 100, and an input device attached to a personal computer and a mobile terminal. Examples of the input device include, for example, a keyboard, a touch panel, a mouse, and a voice recognition device.

The acquisition unit 12 acquires temperature information from the voltage measured by the measurement unit 11 according to a table that specifies the temperature-voltage characteristics that indicate the relationship between the sensed temperature of the temperature detection element 300 and the output voltage. In other words, the acquisition unit 12 performs a process of converting the value of the voltage measured by the measurement unit 11 into temperature information using the table.

The correction unit 13 corrects the acquisition process by the acquisition unit 12 using the correction amount set by the setting unit 14, and causes the acquisition unit 12 to output the corrected temperature information. The correction unit 13 operates in this manner in normal mode. The corrected temperature information output from the acquisition unit 12 is sent to the upper control unit 3.

Next, several circuit configuration forms of the measurement unit 11 are listed. In both the first and second forms, the temperature detection element 300 is connected to the measurement unit 11 in normal mode, and the temperature detection element 300 is removed from the measurement unit 11 in setting mode. When the setting mode ends and the mode transitions to normal mode, the temperature detection element 300 can be attached to the measurement unit 11 at any time.

Figure 2 shows a first form of the measurement unit in a temperature detection device according to one embodiment of the present disclosure, where (A) shows the connection relationship between the measurement unit and the temperature detection element in normal mode, and (B) shows the connection relationship between the measurement unit and the temperature detection element in setting mode.

The measurement unit 11 in the first embodiment has a first voltage dividing resistor 21, a second voltage dividing resistor 23, an operational amplifier 24, and an analog-to-digital conversion unit 22. The measurement unit 11 in the first embodiment also has a fourth voltage dividing resistor 27 as an option.

The first voltage dividing resistor 21 in the measuring unit 11 according to the first embodiment is connected in series to the temperature detection element 300 via one of the two electrode terminals of the temperature detection element 300 in the normal mode. The second voltage dividing resistor 23 is connected in series to the first voltage dividing resistor 21, and in the normal mode, is connected in parallel to the temperature detection element 300 via the two electrode terminals of the temperature detection element 300. As long as the temperature detection element 300 is connected in parallel to the second voltage dividing resistor 23, the first voltage dividing resistor 21 and the second voltage dividing resistor 23 may be connected in series in an interchangeable manner. In this way, in the measuring unit 11 according to the first embodiment, a voltage dividing circuit is formed in which the first voltage dividing resistor 21 and the second voltage dividing resistor 23 are connected in series, but in the example shown in FIG. 2(A), an optional fourth voltage dividing resistor 27 is further connected in series to this voltage dividing circuit.

A predetermined voltage (e.g., 5 [V]) is applied to the voltage divider circuit formed by connecting the first voltage divider resistor 21, the second voltage divider resistor 23, and the fourth voltage divider resistor 27 in series. The predetermined voltage is supplied, for example, from a control power supply (not shown). In the normal mode, the temperature detection element 300 is connected to the measurement unit 11, and in the setting mode, the temperature detection element 300 is removed from the measurement unit 11. Therefore, in the normal mode shown in FIG. 2 (A), the predetermined voltage is divided by the first voltage divider resistor 21, the combined resistance of the temperature detection element 300 and the second voltage divider resistor 23 connected in parallel, and the fourth voltage divider resistor 27. On the other hand, in the setting mode shown in FIG. 2 (B), the predetermined voltage is divided by the first voltage divider resistor 21, the second voltage divider resistor 23, and the fourth voltage divider resistor 27. In both normal mode and setting mode, the potentials appearing at both ends of the second voltage dividing resistor 23 are input to the operational amplifier 24.

In the measurement unit 11 according to the first embodiment, the operational amplifier 24, which is a differential amplifier circuit, extracts an analog signal related to the voltage appearing across the second voltage-dividing resistor 23 by taking the difference between the potentials appearing across the second voltage-dividing resistor 23, and amplifies this to a signal level suitable for input to the analog-to-digital conversion unit 22. The analog signal related to the voltage output from the operational amplifier 24 is sent to the analog-to-digital conversion unit 22.

The analog-digital conversion unit 22 in the measurement unit 11 in the first embodiment converts the analog signal related to the voltage output from the operational amplifier 24 into data in a digital signal format and outputs it. A reference signal REF is input to the analog-digital conversion unit 22 so that a digital signal with a predetermined number of bits (e.g., 12 bits) is output from the analog-digital conversion unit 22. The digital signal data related to the voltage output from the analog-digital conversion unit 22 is sent to the acquisition unit 12 in the normal mode shown in FIG. 2(A), and is sent to the setting unit 14 in the setting mode shown in FIG. 2(B). The digital signal data related to the voltage output from the analog-digital conversion unit 22 in the setting mode is used in the setting unit 14 in the setting mode for setting the correction amount, as described below.

Figure 3 shows a second form of the measurement unit in a temperature detection device according to one embodiment of the present disclosure, where (A) shows the connection relationship between the measurement unit and the temperature detection element in normal mode, and (B) shows the connection relationship between the measurement unit and the temperature detection element in setting mode.

The measurement unit 11 in the second embodiment has a first voltage dividing resistor 21, a third voltage dividing resistor 25, a switch 26, an operational amplifier 24, and an analog-to-digital conversion unit 22.

The first voltage dividing resistor 21 in the measuring unit 11 in the second embodiment is connected in series to the temperature detection element 300 via one of the two electrode terminals of the temperature detection element 300 in normal mode.

In the measuring unit 11 according to the second embodiment, the switch 26 and the third voltage dividing resistor 25 are connected in series. The temperature detection element 300 is connected in parallel to the switch 26 and the third voltage dividing resistor 25 connected in series via the two electrode terminals of the temperature detection element 300, thereby forming a voltage dividing circuit. As long as the temperature detection element 300 is connected in parallel to the switch 26 and the third voltage dividing resistor 25 connected in series, the first voltage dividing resistor 21 and the third voltage dividing resistor 25 may be connected in series in an interchangeable manner. In the normal mode shown in FIG. 3(A), the switch 26 is in an open state, and therefore the electrical connection between the third voltage dividing resistor 25 and the first voltage dividing resistor 21 is released. In the setting mode shown in FIG. 3(B), the switch 26 is in a closed state, and therefore the third voltage dividing resistor 25 and the first voltage dividing resistor 21 are electrically connected. The switch 26 is switched from an open state to a closed state, for example, when the receiver 31 in the setting unit 14 receives a setting start command, which is a command to start the setting mode. Also, for example, the switch 26 is switched from a closed state to an open state when the receiver 31 in the setting unit 14 receives a setting end command, which is a command to end the setting mode. Examples of the switch 26 include a relay, a semiconductor switching element, and an electromagnetic contactor. Examples of the semiconductor switching element include an FET, an IGBT, a thyristor, a GTO, and a transistor. Here, the on-resistance value of the switch 26 in the closed state is 0 [Ω].

A predetermined voltage (e.g., 5 V) is applied to the voltage divider circuit, which is configured by connecting the first voltage divider resistor 21, the switch 26, and the third voltage divider resistor 25 in series. The predetermined voltage is supplied, for example, from a control power supply (not shown). In the normal mode shown in FIG. 3(A), the temperature detection element 300 is connected to the measurement unit 11, the switch 26 is in an open state, and the predetermined voltage is divided by the first voltage divider resistor 21 and the temperature detection element 300. Therefore, in the normal mode, each potential appearing at the two electrode terminals of the temperature detection element 300 is input to the operational amplifier 24. On the other hand, in the setting mode shown in FIG. 3(B), the temperature detection element 300 is removed from the measurement unit 11, the switch 26 is in a closed state, and the predetermined voltage is divided by the first voltage divider resistor 21 and the third voltage divider resistor 25. Therefore, in the setting mode, the potentials appearing at both ends of the third voltage dividing resistor 25 are input to the operational amplifier 24.

In the measurement unit 11 according to the second embodiment, the operational amplifier 24, which is a differential amplifier circuit, extracts an analog signal related to the voltage appearing between the two electrode terminals of the temperature detection element 300 by taking the difference between the potentials appearing at the two electrode terminals of the temperature detection element 300 in the normal mode, and amplifies this to a signal level suitable for the input of the analog-digital conversion unit 22. In addition, the operational amplifier 24 is a differential amplifier circuit that extracts an analog signal related to the voltage appearing across the third voltage-dividing resistor 25 by taking the difference between the potentials appearing at both ends of the third voltage-dividing resistor 25 in the setting mode, and amplifies this to a signal level suitable for the input of the analog-digital conversion unit 22. The analog signal related to the voltage output from the operational amplifier 24 is sent to the analog-digital conversion unit 22.

The operation of the analog-to-digital conversion unit 22 in the measurement unit 11 in the second embodiment is similar to the operation of the analog-to-digital conversion unit 22 in the measurement unit 11 in the first embodiment described with reference to FIG. 2.

The setting unit 14 sets the correction amount used to correct the acquisition process by the acquisition unit 12 according to the voltage in the form of a digital signal output by the measurement unit 11 in the first or second form described above in the setting mode.

Here, we will explain the characteristics of the temperature detection element 300.

Figure 4 is a diagram illustrating temperature-resistance characteristics showing the relationship between the sensed temperature and resistance value of the temperature detection element. Figure 5 is a diagram illustrating temperature-voltage characteristics showing the relationship between the sensed temperature and output voltage of the temperature detection element. Note that the numerical values and curve shapes related to the characteristics of the temperature detection element 300 shown in Figures 4 and 5 are merely examples.

4 and 5, as examples of the temperature detection element 300, element A, whose resistance value decreases with increasing temperature, element B, whose resistance value increases with increasing temperature, and element C, whose resistance value increases with increasing temperature, are illustrated. The rate of increase in resistance with increasing temperature is different between element B and element C. In the normal mode in which the temperature detection element 300 (element A, element B, or element C) is connected to the measurement unit 11, when a predetermined voltage (e.g., 5 [V]) is applied to the voltage divider circuit including the first voltage divider resistor 21 as described above, a digital signal regarding the voltage related to the temperature detection element 300 is output from the analog-digital conversion unit 22. When the sensed temperature of the temperature detection element 300 changes, the resistance value between the two electrode terminals of the temperature detection element 300 changes, and accordingly, the digital signal regarding the voltage related to the temperature detection element 300 output from the analog-digital conversion unit 22 also changes. In this way, there is a one-to-one correspondence between the change in the resistance value of the temperature detection element 300 and the change in the voltage value between the two electrode terminals of the temperature detection element 300. Therefore, a temperature-voltage characteristic (Figure 5) corresponding to the temperature-resistance characteristic (Figure 4) is obtained.

The temperature-resistance characteristics and temperature-voltage characteristics differ for each type of temperature detection element 300 (e.g., element A, element B, or element C). For this reason, the acquisition unit 12 is configured to hold a table that specifies the temperature-voltage characteristics corresponding to the type of temperature detection element 300 connected to the measurement unit 11. In normal mode, the acquisition unit 12 executes a process of acquiring temperature information from the voltage measured by the measurement unit 11 according to the table that specifies the temperature-voltage characteristics corresponding to the type of temperature detection element 300 connected to the measurement unit 11.

The process of acquiring temperature information by the acquisition unit 12 in the normal mode is corrected by the correction unit 13 using the correction amount set by the setting unit 14. This correction amount is set as follows according to the voltage (actual value) measured by the measurement unit 11 in the setting mode.

For example, in the measurement unit 11 having the circuit configuration according to the first embodiment, in the setting mode as shown in FIG. 2B, the above-mentioned predetermined voltage (for example, 5 [V]) is divided by a voltage dividing circuit configured by a series connection of the first voltage dividing resistor 21, the second voltage dividing resistor 23, and the fourth voltage dividing resistor 27. At this time, the voltage appearing at both ends of the second voltage dividing resistor 23 is measured by the measurement unit 11, and digital signal data related to this voltage (actual measurement value) is sent to the setting unit 14. The setting unit 14 calculates the ratio of the actual measurement value of the voltage to the theoretical value (= actual measurement value ÷ theoretical value). The theoretical value (typical value) can be calculated in advance based on the value of the above-mentioned predetermined voltage and the resistance values of the first voltage dividing resistor 21, the second voltage dividing resistor 23, and the fourth voltage dividing resistor 27. This theoretical value is stored in advance in the setting unit 14 for use in calculating the correction amount.

For example, in the measurement unit 11 having the circuit configuration according to the second embodiment, in the setting mode as shown in FIG. 3B, the above-mentioned predetermined voltage (for example, 5 [V]) is divided by a voltage dividing circuit configured by connecting the first voltage dividing resistor 21 and the third voltage dividing resistor 25 in series. At this time, the voltage appearing at both ends of the third voltage dividing resistor 25 is actually measured by the measurement unit 11, and digital signal data related to this voltage (actual measurement value) is sent to the setting unit 14. The setting unit 14 calculates the ratio of the actual measurement value of the voltage to the theoretical value (= actual measurement value ÷ theoretical value). The theoretical value (typical value) can be calculated in advance based on the value of the above-mentioned predetermined voltage and the resistance values of the first voltage dividing resistor 21 and the third voltage dividing resistor 25. This theoretical value is stored in advance in the setting unit 14 for use in calculating the correction amount.

Each component, such as the voltage divider resistors 21, 23, 25, and 27, the operational amplifier 24, and the analog-digital conversion unit 22, that constitute the measurement unit 11 that measures the voltage value of the temperature detection element 300, has individual characteristic variations and characteristic variations over time. If there is no characteristic variation in each component that constitutes the measurement unit 11, the actual measured value of the voltage output from the measurement unit 11 in the setting mode will match the theoretical value. However, in reality, there is a characteristic variation in each individual component and a characteristic variation over time, so the actual measured value of the voltage output from the measurement unit 11 in the setting mode will deviate from the theoretical value. Therefore, in one embodiment of the present disclosure, the deviation of the actual measured value of the voltage from the theoretical value due to the characteristic variation in each component that constitutes the measurement unit 11 is taken as a ratio of the actual measured value of the voltage to the theoretical value (= actual measured value ÷ theoretical value), and the setting unit 14 sets the reciprocal of the ratio (= theoretical value ÷ actual measured value) as the correction amount. When there is no deviation between the actual voltage value output from the measuring unit 11 and the theoretical value due to the variation in the characteristics of each component constituting the measuring unit 11, the correction amount is "1.0", and the temperature information acquired by the acquiring unit 12 is output as is without correction. On the other hand, when the actual voltage value deviates from the theoretical value in the positive direction due to the variation in the characteristics of each component constituting the measuring unit 11, the correction amount is a value smaller than "1.0", and therefore, the temperature information acquired by the acquiring unit 12 is output as a smaller value due to the correction process by the correcting unit 13. On the other hand, when the actual voltage value deviates from the theoretical value in the negative direction due to the variation in the characteristics of each component constituting the measuring unit 11, the correction amount is a value larger than "1.0", and therefore, the temperature information acquired by the acquiring unit 12 is output as a larger value due to the correction process by the correcting unit 13. In this way, the ratio of the actual voltage value to the theoretical value (=actual value ÷ theoretical value) can be said to be an index showing the variation in the characteristics of each component constituting the measurement unit 11, so in one embodiment of the present disclosure, the temperature information acquisition process by the acquisition unit 12 is corrected using a correction amount defined as the inverse of the ratio of the actual voltage value to the theoretical value (=theoretical value ÷ actual value), thereby eliminating the effects of variation in the characteristics of each component constituting the measurement unit 11. One example is as follows.

For example, when the ratio of the actual voltage value measured by the measurement unit 11 to the theoretical value in the setting mode is "1.0", there is no deviation between the actual voltage value and the theoretical value of the voltage output from the measurement unit 11 due to the variation in the characteristics of each component constituting the measurement unit 11, and the setting unit 14 sets the reciprocal of this ratio, "1.0/1.0=1.0", as the correction amount. Also, for example, when the ratio of the actual voltage value measured by the measurement unit 11 to the theoretical value in the setting mode is "0.9", the setting unit 14 sets the reciprocal, "1.0/0.9=1.1", as the correction amount. Also, for example, when the ratio of the actual voltage value measured by the measurement unit 11 to the theoretical value in the setting mode is "1.25", the setting unit 14 sets the reciprocal, "1/1.25=0.8", as the correction amount.

The setting unit 14 notifies the correction unit 13 of the correction amount set as described above. In the normal mode, the correction unit 13 sends correction instruction data regarding the correction amount to the acquisition unit 12, corrects the acquisition process by the acquisition unit 12 using the correction amount, and causes the acquisition unit 12 to output the corrected temperature information.

Next, several forms of correction processing by the correction unit 13 will be listed. In all of the first, second, and third forms, the correction unit 13 operates in normal mode.

First, the first form of correction processing will be described with reference to Figures 6 and 7.

Figure 6 is a diagram illustrating a first form of correction processing in a temperature detection device and a motor drive device including the same according to one embodiment of the present disclosure.

In the first form of correction processing, a table is prepared in advance in which the temperature-voltage characteristics corresponding to each of a number of different correction amounts are specified. The acquisition unit 12 has a memory unit 32 that stores these tables. The correction unit 13 instructs the acquisition unit 12 to select a table corresponding to the correction amount set by the setting unit 14 from the multiple tables stored in the memory unit 32.

FIG. 7 is a diagram illustrating temperature-voltage characteristics corresponding to each of a plurality of different correction amounts. The numerical values and the shape of the curve relating to the characteristics of the temperature detection element 300 shown in FIG. 7 are merely examples. In an ideal case where there is no variation in the characteristics of each component constituting the measurement unit 11, the actual measurement value of the voltage output from the measurement unit 11 in the setting mode coincides with the theoretical value, and the temperature-voltage characteristics at this time are, for example, A _0. If the actual measurement value of the voltage deviates from the theoretical value due to the variation in the characteristics of each component constituting the measurement unit 11, the ratio of the actual measurement value of the voltage to the theoretical value changes, and the correction amount to be set also changes. Since the corrected voltage value can be obtained by multiplying each voltage value along the ideal temperature-voltage characteristic A ₀ by the correction amount set by the setting unit 14, it is possible to obtain temperature-voltage characteristics corresponding to each of a plurality of different correction amounts. Here, A _-2 , A _-1 , A ₁ , and A ₂ are used as examples. The more the actual voltage value deviates from the theoretical value in the positive direction according to the degree of variation in the characteristics of each component constituting the measuring unit 11, the more the temperature-voltage characteristic selected by the correcting unit 13 moves away from _A0 and changes from _A1 to _A2 . The more the actual voltage value deviates from the theoretical value in the negative direction according to the degree of variation in the characteristics of each component constituting the measuring unit 11, the more the temperature-voltage characteristic selected by the correcting unit 13 moves away from _A0 and changes from A _-1 to A _{- 2. In a first form of correction processing, a table is prepared in advance for each of a plurality of different correction amounts, in which a temperature-voltage characteristic obtained by multiplying each voltage value along the ideal temperature-voltage characteristic A0} by the correction amount is specified. The table in which the temperature-voltage characteristic corresponding to the correction amount is specified is stored in advance in the storage unit 32. In the normal mode, the correcting unit 13 sends correction instruction data to the acquiring unit 12 for selecting a table corresponding to the correction amount set by the setting unit 14 from among a plurality of tables stored in the storage unit 32. The acquiring unit 12, which has received the correction instruction data, selects a table corresponding to the correction amount, and executes a process of acquiring temperature information from the voltage measured by the measuring unit 11 according to this table. As a result, the acquiring unit 12 outputs the corrected temperature information. Note that, if a table corresponding to the correction amount set by the setting unit 14 is not stored in the storage unit 32, the acquiring unit 12 may select a table corresponding to the correction amount closest to the correction amount set by the setting unit 14.

Next, we will explain the second form of correction processing.

In the second form of the correction process, a table that specifies the temperature-voltage characteristics (for example, A ₀ in FIG. 7 ) in an ideal case where there is no variation in the characteristics of each component constituting the measuring unit 11 is prepared in advance and stored in the storage unit 32. The correction unit 13 sends correction instruction data to the acquiring unit 12, which instructs the acquiring unit 12 to correct the table that specifies the temperature-voltage characteristics stored in the storage unit 32 according to the correction amount set by the setting unit 14. The acquiring unit 12 that receives the correction instruction data creates a table that specifies the temperature-voltage characteristics that show the relationship between the temperature and the corrected voltage value by multiplying each voltage value according to the temperature-voltage characteristics stored in the storage unit 32 by the correction amount set by the setting unit 14, and executes a process of acquiring temperature information from the voltage measured by the measuring unit 11 according to this table. As a result, the acquiring unit 12 outputs the corrected temperature information.

Next, we will explain the third form of correction processing.

In the third form of the correction process, a table that specifies the temperature-voltage characteristics (for example, A ₀ in FIG. 7 ) in an ideal case where there is no variation in the characteristics of each component constituting the measuring unit 11 is prepared in advance and stored in the storage unit 32. The correction unit 13 sends correction instruction data to the acquiring unit 12, which instructs the acquiring unit 12 to correct the value of the voltage measured by the measuring unit 11 used when the acquiring unit 12 acquires temperature information according to the table in which the temperature-voltage characteristics are specified, based on the correction amount, according to the correction amount set by the setting unit 14. The acquiring unit 12 that has received the correction instruction data multiplies the value of the voltage measured by the measuring unit 11 by the correction amount set by the setting unit 14 to obtain a corrected voltage, and executes a process of acquiring temperature information from the corrected voltage according to the table in which the temperature-voltage characteristics are specified. As a result, the acquiring unit 12 outputs the corrected temperature information.

The above-mentioned acquisition unit 12, correction unit 13, setting unit 14, upper control unit 3, and control circuit in the motor control unit 2 may be composed of only an arithmetic processing device, or may be composed of a combination of an analog circuit and an arithmetic processing device, or may be composed of only an analog circuit. The arithmetic processing device that can configure the acquisition unit 12, correction unit 13, setting unit 14, upper control unit 3, and control circuit in the motor control unit 2 includes, for example, IC, LSI, CPU, MPU, DSP, etc. For example, when the acquisition unit 12, correction unit 13, setting unit 14, upper control unit 3, and control circuit in the motor control unit 2 are constructed in the form of a software program, the acquisition unit 12, correction unit 13, setting unit 14, upper control unit 3, and control circuit in the motor control unit 2 can be realized by operating the arithmetic processing device according to this software program. Alternatively, the acquisition unit 12, correction unit 13, setting unit 14, upper control unit 3, and control circuit in the motor control unit 2 may be realized as a semiconductor integrated circuit in which a software program that realizes the function of each unit is written. Alternatively, the acquisition unit 12, the correction unit 13, the setting unit 14, the upper control unit 3, and the control circuit in the motor control unit 2 may be realized as a recording medium on which a software program that realizes the function of each unit is written. Also, the acquisition unit 12, the correction unit 13, the setting unit 14, the upper control unit 3, and the control circuit in the motor control unit 2 may be provided, for example, in a numerical control device of a machine tool, or in a robot controller that controls a robot.

The memory unit 32 is composed of a non-volatile memory that can be electrically erased and recorded, such as an EEPROM (registered trademark), or a random access memory that can be read and written at high speed, such as a DRAM or SRAM.

As described above, the temperature detection device 1 according to an embodiment of the present disclosure corrects the process of acquiring temperature information from the voltage measured by the measurement unit 11 according to a table that specifies the temperature-voltage characteristics that indicate the relationship between the sensed temperature of the temperature detection element 300 and the output voltage, with a correction amount set according to the voltage (actual value) measured by the measurement unit 11 in the setting mode in which the temperature detection element 300 is removed. This correction amount is set as the reciprocal of the ratio of the actual value of the voltage measured by the measurement unit 11 to the theoretical value in the setting mode in which the temperature detection element 300 is removed (= theoretical value ÷ actual value). The ratio of the actual value of the voltage measured by the measurement unit 11 to the theoretical value in the setting mode in which the temperature detection element 300 is removed can be said to be an index showing the variation in the characteristics of each component that constitutes the measurement unit 11, so that in the normal mode, the reciprocal of this ratio is used as a correction amount to correct the acquisition process of temperature information by the acquisition unit 12, thereby eliminating the influence of the variation in the characteristics of each component that constitutes the measurement unit 11.

When the same measuring unit 11 is to be able to detect the output voltage of more types of temperature detection elements 300, a table in which the temperature-voltage characteristics corresponding to the temperature detection elements 300 to be detected are specified is stored in the acquiring unit 12, and one of the correction processes according to the first to third forms described above is executed. According to the temperature detection device 1 according to an embodiment of the present disclosure, the inverse of the ratio indicating the variation in the characteristics of each component constituting the measuring unit 11 is used as a correction amount to correct the temperature information acquisition process by the acquiring unit 12, thereby eliminating the influence of the variation in measurement accuracy of each measuring unit 11 and the variation over time that occurs when multiple measuring units 11 of the same specification are manufactured using the same type of components, and accurately detecting the temperature. This also makes it possible to avoid a decrease in the resolution of temperature detection that may occur when attempting to detect the output voltage of more types of temperature detection elements with the same measuring unit 11.

REFERENCE SIGNS LIST 1 Temperature detection device 2 Motor control unit 3 Upper control unit 4 Display unit 11 Measurement unit 12 Acquisition unit 13 Correction unit 14 Setting unit 21 First voltage dividing resistor 22 Analog-to-digital conversion unit 23 Second voltage dividing resistor 24 Operational amplifier 25 Third voltage dividing resistor 26 Switch 27 Fourth voltage dividing resistor 31 Receiving unit 32 Storage unit 100 Motor drive device 200 Motor 300 Temperature detection element

Claims (8)

a measurement unit that measures a voltage outputted via two electrode terminals of a temperature detection element, the resistance value between the two electrode terminals of which changes in response to a temperature change;
an acquisition unit that acquires temperature information from the voltage measured by the measurement unit according to a table that defines a temperature-voltage characteristic that indicates a relationship between a sensed temperature of the temperature detection element and an output voltage;
a correction unit that corrects the acquisition process performed by the acquisition unit using a set correction amount and causes the acquisition unit to output corrected temperature information;
a setting unit that sets the correction amount in accordance with the voltage measured by the measurement unit in a setting mode;
Equipped with
the measurement unit has a first voltage dividing resistor connected in series to the temperature detection element via one of the two electrode terminals, and a second voltage dividing resistor connected in series to the first voltage dividing resistor and connected in parallel to the temperature detection element via the two electrode terminals,
The temperature detection device, in the setting mode, wherein the setting unit sets the correction amount in accordance with the voltage appearing across the second voltage dividing resistor measured by the measurement unit when the temperature detection element is detached from the measurement unit. a measurement unit that measures a voltage outputted via two electrode terminals of a temperature detection element, the resistance value between the two electrode terminals of which changes in response to a temperature change;
an acquisition unit that acquires temperature information from the voltage measured by the measurement unit according to a table that defines a temperature-voltage characteristic that indicates a relationship between a sensed temperature of the temperature detection element and an output voltage;
a correction unit that corrects the acquisition process performed by the acquisition unit using a set correction amount and causes the acquisition unit to output corrected temperature information;
a setting unit that sets the correction amount in accordance with the voltage measured by the measurement unit in a setting mode;
Equipped with
the acquisition unit has a storage unit that stores the table in which the temperature-voltage characteristics corresponding to the correction amount are defined for a plurality of different correction amounts;
The correction unit selects a table to be used in the acquisition process by the acquisition unit from among the plurality of tables stored in the memory unit, in accordance with the correction amount set by the setting unit. a measurement unit that measures a voltage outputted via two electrode terminals of a temperature detection element, the resistance value between the two electrode terminals of which changes in response to a temperature change;
an acquisition unit that acquires temperature information from the voltage measured by the measurement unit according to a table that defines a temperature-voltage characteristic that indicates a relationship between a sensed temperature of the temperature detection element and an output voltage;
a correction unit that corrects the acquisition process performed by the acquisition unit using a set correction amount and causes the acquisition unit to output corrected temperature information;
a setting unit that sets the correction amount in accordance with the voltage measured by the measurement unit in a setting mode;
Equipped with
The correction unit corrects the table used in the acquisition process by the acquisition unit, in accordance with the correction amount set by the setting unit. the measurement unit has a first voltage dividing resistor connected in series to the temperature detection element via one of the two electrode terminals, and a second voltage dividing resistor connected in series to the first voltage dividing resistor and connected in parallel to the temperature detection element via the two electrode terminals,
4. The temperature detection device according to claim 2, wherein in the setting mode, the setting unit sets the correction amount according to a voltage appearing across the second voltage dividing resistor measured by the measurement unit when the temperature detection element is detached from the measurement unit. the measurement unit includes a first voltage dividing resistor connected in series to the temperature detection element via one of the two electrode terminals, and a third voltage dividing resistor connected in series to the first voltage dividing resistor in place of the temperature detection element in the setting mode and disconnected from the series connection with the first voltage dividing resistor in modes other than the setting mode,
4. The temperature detection device according to claim 2, wherein the setting unit, in the setting mode, sets the correction amount in accordance with a voltage appearing across the third voltage dividing resistor measured by the measurement unit. The temperature detection device according to claim 1 , wherein the correction unit corrects the voltage measured by the measurement unit and used when the acquisition unit acquires the temperature information according to the table, in accordance with the correction amount. The temperature detection device according to any one of claims 1 to 6, wherein the setting unit has a receiving unit that receives a command to start the setting mode, and when the receiving unit receives the command, starts a process to set the correction amount. a motor control unit that controls the driving of the motor;
A temperature detection device according to any one of claims 1 to 7,
Equipped with
A motor drive device, wherein the temperature detection device obtains the corrected temperature information based on a voltage output via the two electrode terminals of the temperature detection element provided in the vicinity of the motor.

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