Electric motor and control device

Abstract

This electric motor comprises: a stator core; a first winding that is wound around the stator core and corresponds to a first phase; a second winding that is wound around the stator core and that corresponds to a second phase which is different from the first phase; a thermistor that is attached to the first winding; and a thermostat that is connected in series with the thermistor, and that is attached to the second winding.

Description

Electric motor and control device

[0001] The present disclosure relates to an electric motor and a control device.

[0002] Conventionally, in order to prevent the windings of an electric motor from overheating and burning, a technique is known in which the temperature of the windings is measured by a temperature sensor and the electric motor is stopped when the temperature exceeds a predetermined temperature (for example, Patent Document 1). The temperature sensor uses, for example, a thermistor or a thermostat.

[0003] International Publication No. 2018 / 021043

[0004] However, if a temperature sensor is attached to only one phase winding, it is not possible to measure the temperature of the other phase windings that do not have temperature sensors attached, and therefore, if only one of the other phase windings overheats, it is not possible to detect that this winding is overheating.

[0005] On the other hand, if a temperature sensor is attached to each phase winding, the wiring for the temperature sensors becomes complicated. Furthermore, the same number of temperature detection circuits as the number of temperature sensors is required. As a result, the configuration of the motor and control device becomes complicated. Therefore, a technology that can measure the temperature of multiple phase windings with a simple device configuration is required.

[0006] The electric motor of the present disclosure includes a stator core, a first winding wound around the stator core and constituting a first phase, a second winding wound around the stator core and constituting a second phase different from the first phase, a thermistor attached to the first winding, and a thermostat connected in series with the thermistor and attached to the second winding.

[0007] The control device of the present disclosure includes a detection unit that detects a combined resistance between the resistance of a thermistor that is wound around the stator core of an electric motor and attached to a first winding that forms a first phase, and the resistance of a thermostat that is wound around the stator core and attached to a second winding that forms a second phase different from the first phase and is connected in series with the thermistor, and an output unit that outputs an alarm when the value of the combined resistance detected by the detection unit is equal to or greater than a first reference value or equal to or less than a second reference value.

[0008] FIG. 1 is a diagram for explaining an electric motor. FIG. 2 is a schematic diagram showing an example of a manner in which a thermistor and a thermostat are attached to each winding. FIG. 3 is a graph showing an example of temperature characteristics of a thermistor and a thermostat. FIG. 4 is a schematic diagram showing an example of a manner in which a thermistor and a thermostat are attached to each winding. FIG. 5 is a schematic diagram showing an example of a manner in which a thermistor and a thermostat are attached to each winding. FIG. 6 is a block diagram showing an example of a hardware configuration of a control device. FIG. 7 is a block diagram showing an example of a function of the control device. FIG. 8 is a flowchart showing an example of processing executed by the control device.

[0009] An electric motor and a control device according to an embodiment of the present disclosure will be described below with reference to the drawings. In the following description, components having the same or similar functions will be assigned the same reference numerals. Duplicate descriptions of those components may be omitted.

[0010] In this application, "based on XX" means "based on at least XX," and includes cases where it is based on other elements in addition to XX. Furthermore, "based on XX" is not limited to cases where XX is used directly, but also includes cases where it is based on XX that has been calculated or processed. "XX" is any element (for example, any information).

[0011] First Embodiment Fig. 1 is a diagram illustrating an electric motor. The electric motor 1 is, for example, a three-phase AC motor. The electric motor 1 is not limited to a three-phase AC motor, and may be a single-phase AC motor. The electric motor 1 may also be a DC motor. The DC motor is, for example, a brushless DC (Direct Current) motor. Note that each embodiment will be described below using a three-phase AC motor.

[0012] The electric motor 1 includes a stator 2 and a rotor 3. The stator 2 includes a stator core 21 and a plurality of windings 22. The plurality of windings 22 include, for example, a first winding 221a, a second winding 222a, and a third winding 223a.

[0013] The stator core 21 is formed by, for example, laminating multiple electromagnetic steel sheets. The electromagnetic steel sheets are processed into a predetermined shape by, for example, press working. The stator core 21 includes a ring-shaped yoke 211 and multiple teeth 212 that protrude from the inner periphery of the yoke 211 toward the central axis of the stator core 21.

[0014] The first winding 221a is wound around the teeth 212 of the stator core 21. The first winding 221a is made of, for example, a copper wire. The first winding 221a is a winding that forms a first phase. The first phase is, for example, a U phase.

[0015] The second winding 222a is wound around the teeth 212 of the stator core 21. The second winding 222a is made of, for example, a copper wire. The second winding 222a is a winding that forms a second phase different from the first phase. The second phase is, for example, a V phase.

[0016] The third winding 223a is wound around the teeth 212 of the stator core 21. The third winding 223a is made of, for example, a copper wire. The third winding 223a is a winding that forms a third phase different from the first phase and the second phase. The third phase is, for example, a W phase.

[0017] The rotor 3 includes, for example, a permanent magnet 31. The rotor 3 rotates due to a magnetic force acting between the stator 2 and the rotor 3.

[0018] The stator 2 further includes a thermistor (not shown) and a thermostat (not shown). The thermistor is an electronic component whose resistance value changes in response to temperature changes. The thermistor is, for example, an NTC (negative temperature coefficient) thermistor. The NTC thermistor is a thermistor whose resistance value decreases gradually as the temperature increases.

[0019] The thermistor may be a PTC (positive temperature coefficient) thermistor, which has a resistance that increases with increasing temperature.

[0020] A thermostat is an electronic component whose resistance is 0 Ω below a certain temperature and becomes infinite above that temperature. In other words, a thermostat is a switch that is turned on below the certain temperature and turned off above that temperature.

[0021] 2 is a schematic diagram showing an example of how the thermistor and thermostat are attached to the respective windings. The thermistor 5 and thermostat 6 are fixed to the respective windings with adhesive. The thermistor 5 and thermostat 6 may be fixed to the respective windings using fasteners other than adhesive.

[0022] The electric motor 1 includes a first winding 221a forming a first phase and a second winding 222a forming a second phase different from the first phase. The first phase is, for example, a U-phase. The second phase is, for example, a V-phase.

[0023] The thermistor 5 is attached to the first winding 221a, and the thermostat 6 is attached to the second winding 222a. In other words, the winding to which the thermistor 5 is attached is the first winding 221a, and the winding to which the thermostat 6 is attached is the second winding 222a.

[0024] The motor 1 further includes one or more first secondary windings 221b forming a first phase and one or more second secondary windings 222b forming a second phase. The one or more first secondary windings 221b are one or more windings that have the same phase as the first winding 221a and to which neither thermistor 5 nor thermostat 6 is attached. The one or more second secondary windings 222b are one or more windings that have the same phase as the second winding 222a and to which neither thermistor 5 nor thermostat 6 is attached.

[0025] The one or more first secondary windings 221b, together with the first winding 221a, form a row of windings that are continuous in the circumferential direction of the stator core 21. In other words, the first winding 221a and the one or more first secondary windings 221b form a first row that are continuously arranged in the circumferential direction of the stator core 21. In the example shown in Fig. 2, two first secondary windings 221b are arranged side by side in the circumferential direction of the stator core 21 together with the first winding 221a.

[0026] The one or more second secondary windings 222b, together with the second winding 222a, form a row of windings that are continuous in the circumferential direction of the stator core 21. In other words, the second winding 222a and the one or more second secondary windings 222b form a second row that are continuously arranged in the circumferential direction of the stator core 21. In the example shown in Fig. 2, two second secondary windings 222b are arranged side by side in the circumferential direction of the stator core 21 together with the second winding 222a.

[0027] The electric motor 1 further includes a plurality of windings 22 constituting a third phase. The third phase is, for example, a W-phase. The plurality of windings 22 constituting the third phase form a row of windings that are continuous in the circumferential direction of the stator core 21. The thermistor 5 and the thermostat 6 are not attached to the plurality of windings 22 constituting the third phase.

[0028] The thermostat 6 is connected in series to the thermistor 5. The temperatures of the first winding 221a and the second winding 222a are measured based on the combined resistance of the thermistor 5 and the thermostat 6.

[0029] 3 is a graph showing an example of the temperature characteristics of the thermistor 5 and the thermostat 6 attached to the first winding 221a and the second winding 222a, respectively. The curve showing a decrease in resistance value as the temperature increases is a line showing the temperature characteristics of the thermistor 5. On the other hand, the line showing the temperature characteristics of the thermostat 6 is drawn so that the resistance is 0 [Ω] when the temperature is below a predetermined temperature T [°C] and becomes infinite when the temperature exceeds the predetermined temperature T [°C]. Here, a resistance of 0 [Ω] does not necessarily have to be exactly 0 [Ω], as long as it is close to 0 [Ω]. The resistance value of the thermostat 6 below the predetermined temperature T [°C] is, for example, the resistance value of copper.

[0030] When the value of the combined resistance is less than a predetermined first reference value R1 [Ω], the value of the combined resistance is the same as the resistance of the thermistor 5. This is because the resistance of the thermostat 6 is 0 [Ω] unless it is infinite. Therefore, when the value of the combined resistance is less than the first reference value R1 [Ω], the temperature of the first winding 221a can be measured based on the value of the combined resistance. For example, it is possible to measure the temperature of the first winding 221a in real time while the electric motor 1 is running.

[0031] However, if the combined resistance is equal to or less than the second reference value R2 [Ω], the temperature of the first winding 221a will be equal to or greater than the predetermined temperature T [°C]. In other words, the first winding 221a is overheated. In this case, the supply of power to the motor 1 may be stopped. Also, as will be described later, an alarm may be output.

[0032] When the combined resistance value is equal to or greater than the first reference value R1 [Ω], i.e., infinite, the temperature of the thermostat 6 is equal to or greater than a predetermined temperature T [°C]. In other words, the second winding 222a is overheated. In this case, the supply of power to the motor 1 may be stopped. Also, as will be described later, an alarm may be output.

[0033] Second Embodiment FIG. 4 is a schematic diagram showing an example of how the thermistor 5 and the thermostat 6 are attached to the respective windings.

[0034] The electric motor 1 includes a first winding 221a forming a first phase, a second winding 222a forming a second phase different from the first phase, and a third winding 223a forming a third phase different from the first and second phases. The first phase is, for example, a U-phase. The second phase is, for example, a V-phase. The third phase is, for example, a W-phase.

[0035] The thermistor 5 is attached to the second winding 222a. In other words, the winding to which the thermistor 5 is attached is the second winding 222a. The thermostat 6 is attached to the first winding 221a and the third winding 223a. In other words, the winding to which the thermostat 6 is attached is the first winding 221a and the third winding 223a.

[0036] The motor 1 further includes one or more first secondary windings 221b forming a first phase, one or more second secondary windings 222b forming a second phase, and one or more third secondary windings 223b forming a third phase.

[0037] The one or more first secondary windings 221b are one or more windings that have the same phase as the first winding 221a and are not equipped with a thermistor 5 or a thermostat 6. The one or more second secondary windings 222b are one or more windings that have the same phase as the second winding 222a and are not equipped with a thermistor 5 or a thermostat 6. The one or more third secondary windings 223b are one or more windings that have the same phase as the third winding 223a and are not equipped with a thermistor 5 or a thermostat 6.

[0038] The one or more first secondary windings 221b, together with the first winding 221a, form a row of windings that are continuous in the circumferential direction of the stator core 21. In other words, the first winding 221a and the one or more first secondary windings 221b form a first row that are continuously arranged in the circumferential direction of the stator core 21. In the example shown in Fig. 4, two first secondary windings 221b are arranged side by side in the circumferential direction of the stator core 21 together with the first winding 221a.

[0039] The one or more second secondary windings 222b, together with the second winding 222a, form a row of windings that are continuous in the circumferential direction of the stator core 21. In other words, the second winding 222a and the one or more second secondary windings 222b form a second row that are continuously arranged in the circumferential direction of the stator core 21. In the example shown in Fig. 4, two second secondary windings 222b are arranged side by side in the circumferential direction of the stator core 21 together with the second winding 222a.

[0040] The one or more third secondary windings 223b, together with the third winding 223a, form a row of windings that are continuous in the circumferential direction of the stator core 21. In other words, the third winding 223a and the one or more third secondary windings 223b form a third row that are continuously arranged in the circumferential direction of the stator core 21. In the example shown in Fig. 4, two third secondary windings 223b are arranged side by side in the circumferential direction of the stator core 21 together with the third winding 223a.

[0041] The two thermostats 6 are connected in series with the thermistor 5. The two thermostats 6 are also connected in series with each other. The temperatures of the first winding 221a, the second winding 222a, and the third winding 223a are measured based on the combined resistance of the thermistor 5 and the two thermostats 6.

[0042] When the value of the combined resistance is less than the first reference value R1 [Ω], the value of the combined resistance is the same as the resistance of the thermistor 5. This is because the resistance of the thermostat 6 is 0 [Ω] unless it is infinite. Therefore, when the value of the combined resistance is less than the first reference value R1 [Ω], the temperature of the second winding 222a can be measured based on the value of the combined resistance. For example, it is possible to measure the temperature of the second winding 222a in real time while the electric motor 1 is running.

[0043] However, if the combined resistance is equal to or less than the second reference value R2 [Ω], the temperature of the second winding 222a will be equal to or higher than the predetermined temperature T [°C]. In other words, the second winding 222a will be overheated. In this case, the supply of power to the electric motor 1 may be stopped.

[0044] If the combined resistance is equal to or greater than the first reference value R1 [Ω], i.e., infinite, the temperature of at least one of the two thermostats 6 is equal to or greater than the predetermined temperature T [°C]. In other words, at least one of the first winding 221a and the third winding 223a is overheated. In this case, for example, the supply of power to the electric motor 1 may be stopped.

[0045] Third Embodiment FIG. 5 is a schematic diagram showing an example of how the thermistor 5 and the thermostat 6 are attached to the respective windings.

[0046] The electric motor 1 includes a first winding 221a forming a first phase and a second winding 222a forming a second phase different from the first phase. The first phase is, for example, a U-phase. The second phase is, for example, a V-phase.

[0047] The thermistor 5 is attached to the first winding 221a, and the thermostat 6 is attached to the second winding 222a. In other words, the winding to which the thermistor 5 is attached is the first winding 221a, and the winding to which the thermostat 6 is attached is the second winding 222a.

[0048] The motor 1 further includes one or more first secondary windings 221b forming a first phase and one or more second secondary windings 222b forming a second phase. The one or more first secondary windings 221b are one or more windings that have the same phase as the first winding 221a and are not equipped with a thermistor 5 or a thermostat 6. The one or more second secondary windings 222b are one or more windings that have the same phase as the second winding 222a and are not equipped with a thermistor 5 or a thermostat 6.

[0049] The one or more first secondary windings 221b, together with the first winding 221a, form a row of windings that are continuous in the circumferential direction of the stator core 21. In other words, the first winding 221a and the one or more first secondary windings 221b are arranged continuously in the circumferential direction of the stator core 21 to form a first row.

[0050] Furthermore, the first winding 221a is arranged in the center of the first row. Here, "center" means that the same number of first sub-windings 221b are arranged on both sides of the first winding 221a in the circumferential direction of the stator core 21. For example, if the total number of the first winding 221a and the one or more first sub-windings 221b is three, one first sub-winding 221b is arranged on each side of the first winding 221a.

[0051] However, the number of first secondary windings 221b arranged on both sides of the first winding 221a in the circumferential direction of the stator core 21 does not necessarily have to be exactly the same. For example, if the total number of first windings 221a and first secondary windings 221b is four, the first winding 221a may be either of the two windings closer to the center. That is, one first secondary winding 221b is arranged on one side of the first winding 221a, and two first secondary windings 221b are arranged on the other side. This case also falls within the concept of the first winding 221a being arranged in the center of the first row.

[0052] The one or more second auxiliary windings 222b, together with the second winding 222a, form a row of windings that are continuous in the circumferential direction of the stator core 21. In other words, the second winding 222a and the one or more second auxiliary windings 222b are arranged continuously in the circumferential direction of the stator core 21 to form a second row.

[0053] Furthermore, the second winding 222a is arranged in the center of the second row. Here, "center" means that the same number of second auxiliary windings 222b are arranged on both sides of the second winding 222a in the circumferential direction of the stator core 21. However, the number of second auxiliary windings 222b arranged on both sides of the second winding 222a in the circumferential direction of the stator core 21 does not necessarily have to be strictly the same. For example, if the total number of second windings 222a and second auxiliary windings 222b is four, the second winding 222a may be any of the two windings closer to the center. This case also falls within the concept of the second winding 222a being arranged in the center of the second row.

[0054] The electric motor 1 further includes a plurality of windings 22 constituting a third phase. The third phase is, for example, a W-phase. The plurality of windings 22 form a row of windings that are continuous in the circumferential direction of the stator core 21. The thermistor 5 and the thermostat 6 are not attached to the plurality of windings 22 constituting the third phase.

[0055] The thermostat 6 is connected in series with the thermistor 5. The temperatures of the first winding 221a and the second winding 222a are measured based on the combined resistance of the thermistor 5 and the thermostat 6.

[0056] When the value of the combined resistance is less than the first reference value R1 [Ω], the value of the combined resistance is approximately the same as the resistance of the thermistor 5. This is because the resistance of the thermostat 6 is 0 [Ω] unless it is infinite. Therefore, when the value of the combined resistance is less than the first reference value R1 [Ω], the temperature of the first winding 221a can be measured based on the value of the combined resistance.

[0057] However, if the combined resistance is equal to or less than the second reference value R2 [Ω], the temperature of the first winding 221a will be equal to or higher than the predetermined temperature T [°C]. In other words, the first winding 221a will be overheated. In this case, the supply of power to the electric motor 1 may be stopped.

[0058] In this embodiment, the first winding 221a to which the thermistor 5 is attached is located at the center of the first row, so that if only the first phase winding 22 is overheating, this overheating can be detected more reliably.

[0059] If the combined resistance is equal to or greater than the first reference value R1 [Ω], i.e., infinite, the temperature of the thermostat 6 is equal to or greater than the predetermined temperature T [°C]. In other words, the second winding 222a is overheated. In this case, for example, the supply of power to the electric motor 1 may be stopped.

[0060] In this embodiment, the second winding 222a to which the thermostat 6 is attached is located in the center of the second row, so that if only the second phase winding 22 is overheated, this overheating can be detected more reliably.

[0061] Fourth Embodiment FIG. 6 is a schematic diagram showing an example of how the thermistor 5 and the thermostat 6 are attached to the respective windings.

[0062] The electric motor 1 includes a first winding 221a forming a first phase, a second winding 222a forming a second phase different from the first phase, and a third winding 223a forming a third phase different from the first and second phases. The first phase is, for example, a U-phase. The second phase is, for example, a V-phase. The third phase is, for example, a W-phase.

[0063] The thermistor 5 is attached to the second winding 222a. In other words, the winding to which the thermistor 5 is attached is the second winding 222a. The thermostat 6 is attached to the first winding 221a and the third winding 223a. In other words, the winding to which the thermostat 6 is attached is the first winding 221a and the third winding 223a.

[0064] The motor 1 further includes one or more first secondary windings 221b forming a first phase, one or more second secondary windings 222b forming a second phase, and one or more third secondary windings 223b forming a third phase.

[0065] The one or more first secondary windings 221b and the one or more second secondary windings 222b are as described above. The one or more third secondary windings 223b are one or more windings that have the same phase as the third winding 223a and to which neither the thermistor 5 nor the thermostat 6 is attached.

[0066] The one or more first secondary windings 221b, together with the first winding 221a, form a row of windings that are continuous in the circumferential direction of the stator core 21. In other words, the first winding 221a and the one or more first secondary windings 221b form a first row that is continuously arranged in the circumferential direction of the stator core 21. The first winding 221a is also arranged in the center of the first row.

[0067] The one or more second auxiliary windings 222b, together with the second winding 222a, form a row of windings that are continuous in the circumferential direction of the stator core 21. In other words, the second winding 222a and the one or more second auxiliary windings 222b are arranged continuously in the circumferential direction of the stator core 21 to form a second row. The second winding 222a is arranged in the center of the second row.

[0068] The one or more third auxiliary windings 223b, together with the third winding 223a, form a row of windings that are continuous in the circumferential direction of the stator core 21. In other words, the third winding 223a and the one or more third auxiliary windings 223b form a third row that is continuously arranged in the circumferential direction of the stator core 21. The third winding 223a is also arranged in the center of the third row.

[0069] Here, "center" means that the same number of third auxiliary windings 223b are arranged on both sides of the third winding 223a in the circumferential direction of the stator core 21. However, the number of third auxiliary windings 223b arranged on both sides of the third winding 223a in the circumferential direction of the stator core 21 does not necessarily have to be strictly the same. For example, if the total number of third windings 223a and third auxiliary windings 223b is four, the third winding 223a may be any one of the two windings 22 closer to the center. This case also falls within the concept of the third winding 223a being arranged in the center of the third row.

[0070] The two thermostats 6 are connected in series with the thermistor 5. The two thermostats 6 are also connected in series with each other. The temperatures of the first winding 221 a, the second winding 222 a, and the third winding 223 a are measured based on the combined resistance of the thermistor 5 and the two thermostats 6.

[0071] When the value of the combined resistance is less than the first reference value R1 [Ω], the value of the combined resistance is the same as the resistance of the thermistor 5. This is because the resistance of the thermostat 6 is 0 [Ω] unless it is infinite. Therefore, when the value of the combined resistance is less than the first reference value R1 [Ω], the temperature of the second winding 222a can be measured based on the value of the combined resistance.

[0072] [Correction based on Rule 91, 20.11.2024] However, if the combined resistance is equal to or less than the second reference value R2 [Ω], the temperature of the second winding 222a will exceed the predetermined temperature T [°C]. In other words, the second winding 222a will overheat. In this case, the supply of power to the motor 1 may be stopped.

[0073] In this embodiment, the second winding 222a to which the thermistor 5 is attached is located in the center of the second row, so that if only the second phase winding 22 is overheating, this overheating can be detected more reliably.

[0074] If the combined resistance is equal to or greater than the first reference value R1 [Ω], i.e., infinite, the temperature of at least one of the two thermostats 6 is equal to or greater than the predetermined temperature T [°C]. In other words, at least one of the first winding 221a and the third winding 223a is overheated. In this case, the supply of power to the electric motor 1 may be stopped.

[0075] In this embodiment, the first winding 221a and the third winding 223a to which the thermostat 6 is attached are disposed at the center of the first and third rows, respectively, so that if only the first phase winding 22 or only the third phase winding 22 is overheating, this can be detected more reliably.

[0076] Fifth Embodiment Next, a description will be given of a control device that outputs an alarm when the temperature detected from the electric motor 1 exceeds a predetermined temperature. The control device is, for example, a control device that controls the electric motor 1. The electric motor 1 is at least one of the electric motors 1 disclosed in the first to fourth embodiments described above.

[0077] 7 is a block diagram showing an example of a hardware configuration of a control device 10. The control device 10 is, for example, a numerical control device that controls industrial machinery. The control device 10 may be a computer such as a personal computer (PC), a server, or a tablet terminal.

[0078] The control device 10 includes a hardware processor 11 , a bus 12 , a read-only memory (ROM) 13 , a random access memory (RAM) 14 , a non-volatile memory 15 , and an interface 16 .

[0079] The hardware processor 11 is a processor that controls the entire control device 10 in accordance with a system program. The hardware processor 11 reads the system program stored in the ROM 13 via the bus 12 and performs various processes based on the system program. The hardware processor 11 is, for example, a CPU (Central Processing Unit) or an electronic circuit.

[0080] The bus 12 is a communication path that connects the various pieces of hardware within the control device 10. The various pieces of hardware within the control device 10 exchange data via the bus 12.

[0081] The ROM 13 is a storage device that stores a system program for controlling the entire control device 10. The ROM 13 is a computer-readable storage medium.

[0082] The RAM 14 is a storage device that temporarily stores various data and functions as a work area for the hardware processor 11 to process various data.

[0083] The nonvolatile memory 15 is a storage device that retains data even when the control device 10 is turned off and no power is being supplied to the control device 10. The nonvolatile memory 15 is a computer-readable storage medium. The nonvolatile memory 15 is configured, for example, as a battery-backed memory or an SSD (Solid State Drive).

[0084] The interface 16 connects the bus 12 and the electric motor 1. The control device 10 transmits and receives data to and from the electric motor 1 via the interface 16.

[0085] 8 is a block diagram showing an example of the functions of the control device 10. The control device 10 includes, for example, a control unit 101, a detection unit 102, and an output unit 103. The control unit 101, the detection unit 102, and the output unit 103 are realized, for example, by the hardware processor 11 performing arithmetic processing using a system program stored in the ROM 13 and various data stored in the non-volatile memory 15.

[0086] The control unit 101 controls the operation of the electric motor 1 based on, for example, an operation program stored in a storage unit (not shown).

[0087] The detection unit 102 detects the combined resistance of the resistance of the thermistor 5 and the resistance of the thermostat 6. The thermistor 5 is attached to, for example, a first winding 221a wound around the stator core 21 of the electric motor 1 and forming a first phase. The thermostat 6 is attached to a second winding 222a wound around the stator core 21 and forming a second phase different from the first phase. The thermostat 6 is also connected in series with the thermistor 5.

[0088] The output unit 103 outputs an alarm when the value of the combined resistance detected by the detection unit 102 is equal to or greater than a first reference value or equal to or less than a second reference value. The output unit 103 outputs the alarm to, for example, a display device (not shown) included in the control device 10. The output unit 103 may output the alarm using a rotating light connected to the control device 10.

[0089] Furthermore, when the value of the combined resistance detected by the detection unit 102 becomes equal to or greater than a first reference value or equal to or less than a second reference value, the control unit 101 stops the operation of the electric motor 1 .

[0090] 9 is a flowchart showing an example of processing executed by the control device 10. In the control device 10, first, the control unit 101 executes control of the electric motor 1 (step S1).

[0091] Next, the detection unit 102 detects the combined resistance of the thermistor 5 and the thermostat 6 (step S2). Next, the detection unit 102 determines whether the value of the combined resistance satisfies a predetermined condition (step S3). Specifically, the detection unit 102 determines whether the value of the combined resistance is equal to or greater than a first reference value or equal to or less than a second reference value.

[0092] If the combined resistance does not satisfy the predetermined condition (No in step S3), the detection unit 102 continues to detect the combined resistance.

[0093] If the combined resistance satisfies the predetermined condition (Yes in step S3), the output unit 103 outputs an alarm (step S4). Furthermore, the control unit 101 stops the operation of the electric motor 1 (step S5), and the process ends.

[0094] As described above, the electric motor 1 comprises the stator core 21, the first winding 221a wound around the stator core 21 and constituting a first phase, the second winding 222a wound around the stator core 21 and constituting a second phase different from the first phase, the thermistor 5 attached to the first winding 221a, and the thermostat 6 connected in series to thermistor 5 and attached to the second winding 222a.

[0095] Therefore, even if only one of the first winding 221 a and the second winding 222 a is overheated, the overheating can be detected. Furthermore, since the thermistor 5 and the thermostat 6 are connected in series, it is possible to prevent the wiring from becoming complicated.

[0096] The electric motor 1 further includes one or more first secondary windings 221b forming a first phase, the first winding 221a and the one or more first secondary windings 221b being arranged continuously in the circumferential direction of the stator core 21 to form a first row, the first winding 221a being arranged at the center of the first row. The electric motor 1 further includes one or more second secondary windings 222b forming a second phase, the second winding 222a and the one or more second secondary windings 222b being arranged continuously in the circumferential direction of the stator core 21 to form a second row, the second winding 222a being arranged at the center of the second row.

[0097] For example, if only the first phase winding 22 overheats, the temperature will be highest near the center of the first row. On the other hand, the temperatures near both ends of the first row will be relatively low due to the influence of the ambient temperature. Therefore, by arranging the first winding 221a in the center of the first row, if the first phase winding 22 overheats, the overheating can be detected early. Similarly, by arranging the second winding 222a in the center of the second row, if the second phase winding 22 overheats, the overheating can be detected early.

[0098] The control device 10 also includes a detection unit 102 that detects a combined resistance between the resistance of a thermistor 5 that is wound around the stator core 21 of the electric motor 1 and attached to a first winding 221a that forms a first phase, and the resistance of a thermostat 6 that is wound around the stator core 21 and attached to a second winding 222a that forms a second phase different from the first phase and is connected in series with the thermistor 5, and an output unit 103 that outputs an alarm when the value of the combined resistance detected by the detection unit 102 becomes equal to or greater than a first reference value or equal to or less than a second reference value.

[0099] Therefore, even if only one of the first winding 221 a and the second winding 222 a is overheated, the control device 10 can detect the overheating and can promptly notify the operator that the detection unit 102 has detected overheating.

[0100] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the spirit of the present disclosure, or within the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0101] The following are supplementary notes related to embodiments of the present disclosure. Supplementary note [1] An electric motor comprising: a stator core; a first winding wound around the stator core and forming a first phase; a second winding wound around the stator core and forming a second phase different from the first phase; a thermistor attached to the first winding; and a thermostat connected in series to the thermistor and attached to the second winding. Supplementary note [2] The electric motor according to supplementary note [1], further including one or more first sub-windings forming the first phase, the first winding and the one or more first sub-windings being arranged consecutively in the circumferential direction of the stator core to form a first row, and the first winding being arranged at the center of the first row. and a thermostat connected in series to a second winding that is wound around the stator core and forms a second phase different from the first phase, the thermostat being connected in series to the first winding and a detection unit configured to detect a combined resistance of a thermistor wound around the stator core and attached to a first winding that is wound around the stator core and forms a second phase different from the first phase, and an output unit configured to output an alarm when the value of the combined resistance detected by the detection unit is equal to or greater than a first reference value or equal to or less than a second reference value.

[0102] REFERENCE SIGNS LIST 1 electric motor 2 stator 21 stator core 211 yoke 212 teeth 22 winding 221a first winding 221b first auxiliary winding 222a second winding 222b second auxiliary winding 223a third winding 223b third auxiliary winding 3 rotor 31 permanent magnet 5 thermistor 6 thermostat 10 control device 11 hardware processor 12 bus 13 ROM 14 RAM 15 non-volatile memory 16 interface 101 control unit 102 detection unit 103 output unit

Claims

1. An electric motor comprising: a stator core; a first winding wound around the stator core and constituting a first phase; a second winding wound around the stator core and constituting a second phase different from the first phase; a thermistor attached to the first winding; and a thermostat connected in series to the thermistor and attached to the second winding.

2. The electric motor according to claim 1, further comprising one or more first sub-windings forming the first phase, wherein the first winding and the one or more first sub-windings are successively arranged in the circumferential direction of the stator core to form a first row, and the first winding is arranged in the center of the first row.

3. An electric motor as claimed in claim 1 or 2, further comprising one or more second secondary windings forming the second phase, the second winding and the one or more second secondary windings being successively arranged in the circumferential direction of the stator core to form a second row, and the second winding being arranged in the centre of the second row.

4. A control device comprising: a detection unit that detects a combined resistance of a thermistor wound around a stator core of an electric motor and attached to a first winding forming a first phase, and a thermostat that is wound around the stator core and attached to a second winding forming a second phase different from the first phase and connected in series with the thermistor; and an output unit that outputs an alarm when the value of the combined resistance detected by the detection unit becomes equal to or greater than a first reference value or equal to or less than a second reference value.

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