ELECTRIC MOTOR AND CONTROL DEVICE

Abstract

This electric motor has a stator core; a first winding wound around the stator core, corresponding to a first phase; a second winding wound around the stator core, corresponding to 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.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an electric motor and a controller. GENERAL STATE OF THE ART

[0002] To prevent the winding wire of an electric motor from overheating and burning, a technique has been conventionally known in which the temperature of the winding wire is measured using a temperature sensor and the electric motor is stopped when the temperature exceeds a predetermined temperature (see, for example, Patent Document 1). A thermistor or a thermostat, for example, is used as the temperature sensor. LITERATURE LISTPATENT DOCUMENT

[0003] Patent Document 1: WO 2018 / 021043 SUMMARY OF THE INVENTIONPROBLEM THAT THE INVENTION INTENDED TO SOLVE

[0004] However, if a temperature sensor is attached to only one winding wire of one phase, the temperature of a winding wire of another phase that does not have a temperature sensor cannot be measured. Therefore, if only the winding wire of the other phase is overheated, it is not possible to detect the overheating of the winding wire.

[0005] On the other hand, if a temperature sensor is attached to each winding wire of each phase, the wiring of the temperature sensors becomes complicated. Moreover, as many temperature detection circuits as temperature sensors are required. As a result, the device structure of the electric motor and the controller becomes complicated. Therefore, there is a need for a technology that can measure the temperatures of the winding wires of multiple phases using a simple device structure. MEANS TO SOLVE THE PROBLEM

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

[0007] A controller of the disclosure includes a detection unit configured to detect a composite resistance of a resistance of a thermistor attached to a first winding wire wound around a stator core and constituting a first phase, and a resistance of a thermostat attached to a second winding wire wound around the stator core and constituting a second phase different from the first phase, and connected in series to the thermistor; and an output unit configured to output an alarm when a value of the composite resistance detected by the detection unit becomes greater than or equal to a first reference value or less than or equal to a second reference value. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram describing an electric motor; Fig. 2 is a schematic diagram showing an example of a form in which a thermistor and a thermostat are each attached to individual winding wires; Fig. 3 is a graph showing an example of temperature characteristics of the thermistor and the thermostat; Fig. 4 is a schematic diagram showing an example of a form in which a thermistor and thermostats are each attached to individual winding wires; Fig. 5 is a schematic diagram showing an example of a form in which a thermistor and a thermostat are each attached to individual winding wires; Fig. 6 is a schematic diagram showing an example of a form in which a thermistor and thermostats are each attached to individual winding wires; Fig. 7 is a block diagram showing an example of a hardware structure of a controller; Fig. 8 is a block diagram showing an example of functions of the controller; and Fig. 9 is a flowchart showing an example of the processing executed by the controller. MODE(S) FOR CARRYING OUT THE INVENTION

[0008] With reference to the drawings, an electric motor and a controller according to an embodiment of the disclosure will be described below. Note that in the following description, components having the same or similar functions are denoted by the same reference numerals. Furthermore, duplicate descriptions of these components may be omitted.

[0009] In this application, "based on XX" means "based on at least XX", which also includes "based on other elements in addition to XX". Furthermore, "based on XX" is not limited to a direct use of XX, but also includes "based on an element obtained by calculating or processing XX". "XX" is any element (for example, any information). First Embodiment

[0010] Fig. 1 is a diagram for describing an electric motor. The electric motor 1 is, for example, a three-phase AC electric motor. The electric motor 1 is not limited to the three-phase AC electric motor, but may be a single-phase AC motor. The electric motor 1 may also be a DC electric motor. The DC electric motor is, for example, a brushless DC electric motor (DC electric motor). Note that each embodiment will be described using a three-phase AC electric motor.

[0011] The electric motor 1 has a stator 2 and a rotor 3. The stator 2 has a stator core 21 and a plurality of winding wires 22. The plurality of winding wires 22 include, for example, a first winding wire 221a, a second winding wire 222a, and a third winding wire 223a.

[0012] The stator core 21 is formed, for example, by stacking a plurality of electromagnetic steel sheets. The electromagnetic steel sheets are machined, for example, by pressing, into a predetermined shape. The stator core 21 includes an annular yoke 211 and a plurality of teeth 212 projecting from an inner periphery of the yoke 211 toward a central axis of the stator core 21.

[0013] The first winding wire 221a is wound around the teeth 212 of the stator core 21. The first winding wire 221a is formed, for example, from a copper wire. The first winding wire 221a is a winding wire that forms a first phase. The first phase is, for example, a U-phase.

[0014] The second winding wire 222a is wound around the teeth 212 of the stator core 21. The second winding wire 222a is formed, for example, from a copper wire. The second winding wire 222a is a winding wire that forms a second phase different from the first phase. The second phase is, for example, a V-phase.

[0015] The third winding wire 223a is wound around the teeth 212 of the stator core 21. The third winding wire 223a is formed, for example, from a copper wire. The third winding wire 223a is a winding wire that forms a third phase different from the first phase and the second phase. The third phase is, for example, a W phase.

[0016] The rotor 3, for example, has permanent magnets 31. The rotor 3 rotates due to a magnetic force acting between the stator 2 and the rotor 3.

[0017] 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 a change in temperature. The thermistor is, for example, an NTC thermistor (negative temperature coefficient thermistor). The NTC thermistor is a thermistor whose resistance value gradually decreases in response to a rise in temperature.

[0018] The thermistor can be a PTC thermistor (positive temperature coefficient thermistor). The PTC thermistor is a thermistor whose resistance value increases in response to a rise in temperature.

[0019] A thermostat is an electronic component whose resistance is 0 [Ω] at a predetermined temperature or less and whose resistance becomes infinite when the predetermined temperature is exceeded. In other words, a thermostat is a switch that is turned on at the predetermined temperature or less and turned off when the predetermined temperature is exceeded.

[0020] Fig. Figure 2 is a schematic diagram showing an example of the mounting form of the thermistor and thermostat to individual winding wires. The thermistor 5 and the thermostat 6 are each fixed to individual winding wires using an adhesive. There is no limitation to the adhesive; the thermistor 5 and the thermostat 6 may each be fixed to individual winding wires using a fastener, etc.

[0021] The electric motor 1 has the first winding 221a, which forms the first phase, and the second winding 222a, which forms the 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.

[0022] The thermistor 5 is attached to the first winding wire 221a. The thermostat 6 is attached to the second winding wire 222a. In other words, a winding wire to which the thermistor 5 is attached is the first winding wire 221a. Furthermore, a winding wire to which the thermostat 6 is attached is the second winding wire 222a.

[0023] The electric motor 1 further includes one or more first sub-winding wires 221b constituting the first phase and one or more second sub-winding wires 222b constituting the second phase. The one or more first sub-winding wires 221b are one or more sub-winding wires constituting the same phase as that of the first winding wire 221a and to which neither the thermistor 5 nor the thermostat 6 is attached. Furthermore, the one or more second sub-winding wires 222b are one or more sub-winding wires constituting the same phase as that of the second winding wire 222a and to which neither the thermistor 5 nor the thermostat 6 is attached.

[0024] The one or more first sub-winding wires 221b, together with the first winding wire 221a, form a series of winding wires that are continuous in a circumferential direction of the stator core 21. In other words, the first winding wire 221a and the one or more first sub-winding wires 221b are arranged continuously in the circumferential direction of the stator core 21 and form a first series. In the example shown in Fig. 2, two first sub-winding wires 221b are arranged side by side together with the first winding wire 221a in the circumferential direction of the stator core 21.

[0025] The one or more second sub-winding wires 222b, together with the second winding wire 222a, form a series of winding wires that are continuous in the circumferential direction of the stator core 21. In other words, the second winding wire 222a and the one or more second sub-winding wires 222b are arranged continuously in the circumferential direction of the stator core 21 and form a second series. In the example shown in Fig. 2, two second sub-winding wires 222b are arranged side by side together with the second winding wire 222a in the circumferential direction of the stator core 21.

[0026] The electric motor 1 further includes the plurality of winding wires 22 constituting the third phase. The third phase is, for example, the W phase. The plurality of winding wires 22 constituting the third phase form a series of winding wires 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 winding wires 22 constituting the third phase.

[0027] The thermostat 6 is connected in series to the thermistor 5. A temperature of the first winding wire 221a and a temperature of the second winding wire 222a are measured based on a composite resistance of the resistance of the thermistor 5 and the resistance of the thermostat 6.

[0028] Fig. 3 is a graph showing an example of temperature characteristics of the thermistor 5 and the thermostat 6, which are respectively attached to the first winding wire 221a and the second winding wire 222a. A curve indicating that a resistance value decreases with the increase of a temperature is a line indicating the temperature characteristics of the thermistor 5. A line drawn such that a resistance [0] Ω when the temperature is a predetermined temperature T [°C] or less, and the resistance becomes infinite when the temperature exceeds the predetermined temperature T [°C], in turn, is a line indicating the temperature characteristics of the thermostat 6. Here, the resistance of 0 [Ω] does not have to be exactly 0 [Ω], but may be a resistance close to 0 [Ω]. A resistance value of the thermostat 6 at the predetermined temperature T [°C] or less is, for example, the resistance of copper.

[0029] When a value of the composite resistance is less than a predetermined first reference value R1 [Ω], the value of the composite resistance is the same as the resistance value of the thermistor 5. One reason for this is that the resistance value of the thermostat 6 is 0 [Ω] unless the resistance value is infinite. Therefore, when the value of the composite resistance is less than the first reference value R1 [Ω], the temperature of the first winding wire 221a can be measured based on the value of the composite resistance. For example, it is possible to measure the temperature of the first winding wire 221a in real time while the electric motor 1 is driving.

[0030] However, if the value of the composite resistance is less than or equal to a second reference value R2 [Ω], the temperature of the first winding wire 221a becomes greater than or equal to the predetermined temperature T [°C]. In other words, the first winding wire 221a is overheated. In this case, the power supply to the electric motor 1 may be interrupted. Furthermore, an alarm may be issued as described later.

[0031] When the value of the composite resistance is greater than or equal to the first reference value R1 [Ω], that is, when the value becomes infinite, the temperature of the thermostat 6 is greater than or equal to the predetermined temperature T [°C]. In other words, the second winding wire 222a is overheated. In this case, the power supply to the electric motor 1 may be interrupted. Furthermore, an alarm may be issued as described later. Second embodiment

[0032] Fig. 4 is a schematic diagram showing an example of a form in which a thermistor 5 and thermostats 6 are each attached to individual winding wires.

[0033] The electric motor 1 has a first winding wire 221a forming a first phase, a second winding wire 222a forming a second phase different from the first phase, and a third winding wire 223a forming a third phase different from the first phase and the second phase. 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.

[0034] The thermistor 5 is attached to the second winding wire 222a. In other words, a winding wire to which the thermistor 5 is attached is the second winding wire 222a. Thermostats 6 are attached to the first winding wire 221a and the third winding wire 223a, respectively. In other words, the winding wires to which the thermostats 6 are attached are the first winding wire 221a and the third winding wire 223a.

[0035] The electric motor 1 further comprises one or more first sub-winding wires 221b forming the first phase, one or more second sub-winding wires 222b forming the second phase, and one or more third sub-winding wires 223b forming the third phase.

[0036] The one or more first sub-winding wires 221b are one or more sub-winding wires that form the same phase as that of the first winding wire 221a and to which neither the thermistor 5 nor a thermostat 6 is attached. The one or more second sub-winding wires 222b are one or more winding wires that form the same phase as that of the second winding wire 222a and to which neither the thermistor 5 nor a thermostat 6 is attached. The one or more third sub-winding wires 223b are one or more winding wires that form the same phase as that of the third winding wire 223a and to which neither the thermistor 5 nor a thermostat 6 is attached.

[0037] The one or more first sub-winding wires 221b, together with the first winding wire 221a, form a series of winding wires that are continuous in a circumferential direction of the stator core 21. In other words, the first winding wire 221a and the one or more first sub-winding wires 221b are arranged continuously in the circumferential direction of the stator core 21 and form a first series. In the example shown in Fig. 4, two first sub-winding wires 221b are arranged side by side together with the first winding wire 221a in the circumferential direction of the stator core 21.

[0038] The one or more second sub-winding wires 222b, together with the second winding wire 222a, form a series of winding wires that are continuous in a circumferential direction of the stator core 21. In other words, the second winding wire 222a and the one or more second sub-winding wires 222b are arranged continuously in the circumferential direction of the stator core 21 and form a second series. In the example shown in Fig. 4, two second sub-winding wires 222b are arranged side by side together with the second winding wire 222a in the circumferential direction of the stator core 21.

[0039] The one or more third sub-winding wires 223b, together with the third winding wire 223a, form a series of winding wires that are continuous in a circumferential direction of the stator core 21. In other words, the third winding wire 223a and the one or more third sub-winding wires 223b are continuously arranged in the circumferential direction of the stator core 21 and form a third series. In the example shown in Fig. 4, two third sub-winding wires 223b are arranged side by side together with the third winding wire 223a in the circumferential direction of the stator core 21.

[0040] The two thermostats 6 are connected in series to the thermistor 5. Note that the two thermostats 6 are also connected in series to each other. A temperature of the first winding wire 221a, a temperature of the second winding wire 222a, and a temperature of the third winding wire 223a are measured based on the combined resistance of the resistance of the thermistor 5 and the resistances of the two thermostats 6.

[0041] When a value of the composite resistance is less than the first reference value R1 [Ω], the value of the composite resistance is the same as a resistance value of the thermistor 5. One reason for this is that the resistance value of the thermostat 6 is 0 [Ω] unless the resistance value is infinite. Therefore, when the value of the composite resistance is less than the first reference value R1 [Ω], the temperature of the second winding wire 222a can be measured based on the value of the composite resistance. For example, it is possible to measure the temperature of the second winding wire 222a in real time while the electric motor 1 is driving.

[0042] However, if the value of the composite resistance is less than or equal to a second reference value R2 [Ω], the temperature of the second winding wire 222a becomes greater than or equal to the predetermined temperature T [°C]. In other words, the second winding wire 222a is overheated. In this case, the power supply to the electric motor 1 may be interrupted.

[0043] When the value of the combined resistance is greater than or equal to the first resistance value R1 [Ω], that is, infinite, a temperature of at least one of the two thermostats 6 is greater than or equal to the predetermined temperature T [°C]. In other words, at least one of the first winding wire 221a and the third winding wire 223a is overheated. In this case, the power supply to the electric motor 1 may be interrupted. Third embodiment

[0044] Fig. 5 is a schematic diagram showing an example of a form in which the thermistor 5 and the thermostat 6 are each attached to individual winding wires.

[0045] The electric motor 1 has a first winding wire 221a forming a first phase and a second winding wire 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.

[0046] The thermistor 5 is attached to the first winding wire 221a. The thermostat 6 is attached to the second winding wire 222a. In other words, a winding wire to which the thermistor 5 is attached is the first winding wire 221a. Furthermore, a winding wire to which the thermostat 6 is attached is the second winding wire 222a.

[0047] The electric motor 1 further includes one or more first sub-winding wires 221b forming the first phase and one or more second sub-winding wires 222b forming the second phase. The one or more first sub-winding wires 221b are one or more sub-winding wires 221b forming the same phase as that of the first winding wire 221a and to which neither the thermistor 5 nor the thermostat 6 is attached. The one or more second sub-winding wires 222b are one or more sub-winding wires 222b forming the same phase as that of the second winding wire 222a and to which neither the thermistor 5 nor the thermostat 6 is attached.

[0048] The one or more first sub-winding wires 221b, together with the first winding wire 221a, form a series of winding wires that are continuous in the circumferential direction of the stator core 21. In other words, the first winding wire 221a and the one or more first sub-winding wires 221b are arranged continuously in the circumferential direction of the stator core 21 and form a first series.

[0049] Moreover, the first winding wire 221a is arranged in the center of the first row. Here, the center means that an equal number of first sub-winding wires 221b are arranged on both sides of the first winding wire 221a in the circumferential direction of the stator core 21. For example, if the total number of the first winding wire 221a and the one or more first sub-winding wires 221b is three, one first sub-winding wire 221b is arranged on each side of the first winding wire 221a.

[0050] However, the number of first sub-winding wires 221b arranged on both sides of the first winding wire 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 the first winding wire 221a and the first sub-winding wires 221b is four, the first winding wire 221a may be any of the two winding wires closer to the center. That is, one first sub-winding wire 221b is arranged on one side of the first winding wire 221a, and two first sub-winding wires 221b are arranged on the other side. This case is also included in the concept that the first winding wire 221a is arranged in the center of the first row.

[0051] The one or more second sub-winding wires 222b, together with the second winding wire 222a, form a series of winding wires that are continuous in the circumferential direction of the stator core 21. In other words, the second winding wire 222a and the one or more second sub-winding wires 222b are arranged continuously in the circumferential direction of the stator core 21 and form a first series.

[0052] Moreover, the second winding wire 222a is arranged in the center of the second row. Here, the center means that an equal number of second sub-winding wires 222b are arranged on both sides of the second winding wire 222a in the circumferential direction of the stator core 21. However, the number of second sub-winding wires 222b arranged on both sides of the second winding wire 222a 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 the second winding wire 222a and the second sub-winding wires 222b is four, the second winding wire 222a can be any of the two winding wires closer to the center. This case is also included in the concept that the second winding wire 222a is arranged in the center of the second row.

[0053] The electric motor 1 further includes a plurality of winding wires 22 constituting a third phase. The third phase is, for example, a W phase. The plurality of winding wires 22 form a series of winding wires that are continuous in the circumferential direction of the stator core 21. The thermistor 5 and the thermostat 6 are not connected to the plurality of winding wires 22 constituting the third phase.

[0054] The thermostat 6 is connected in series to the thermistor 5. A temperature of the first winding wire 221a and a temperature of the second winding wire 222a are measured based on the composite resistance of the resistance of the thermistor 5 and the resistance of the thermostat 6.

[0055] When a value of the composite resistance is less than the first reference value R1 [Ω], the value of the composite 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 the resistance is infinite. Therefore, when the value of the composite resistance is less than the first reference value RT1 [Ω], the temperature of the first winding wire 221a can be measured based on the value of the composite resistance.

[0056] However, if the value of the composite resistance is less than or equal to the second reference value R2 [Ω], the temperature of the first winding wire 221a becomes greater than or equal to the predetermined temperature T [°C]. In other words, the first winding wire 221a is overheated. In this case, the power supply to the electric motor 1 may be interrupted.

[0057] In this embodiment, the first winding wire 221a, to which the thermistor 5 is attached, is arranged in the center of the first row. Therefore, when only the winding wire 22 constituting the first phase is overheated, it is possible to detect this overheating more reliably.

[0058] When the value of the composite resistance is greater than or equal to the first reference value R1 [Ω], that is, becomes infinite, the temperature of the thermostat 6 is greater than or equal to the predetermined temperature T [°C]. In other words, the second winding wire 222a is overheated. In this case, the power supply to the electric motor 1 may be interrupted.

[0059] In this embodiment, the second winding wire 222a, to which the thermostat 6 is attached, is arranged in the center of the second row. Therefore, when only the winding wire 22 constituting the second phase is overheated, it is possible to detect this overheating more reliably. Fourth embodiment

[0060] Fig. 6 is a schematic diagram showing an example of a form in which a thermistor 5 and thermostats 6 are each attached to individual winding wires.

[0061] The electric motor 1 has a first winding wire 221a forming a first phase, a second winding wire 222a forming a second phase different from the first phase, and a third winding wire 223a forming a third phase different from the first phase and the second phase. 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.

[0062] The thermistor 5 is attached to the second winding wire 222a. In other words, a winding wire to which the thermistor 5 is attached is the second winding wire 222a. Thermostats 6 are attached to the first winding wire 221a and the third winding wire 223a, respectively. In other words, the winding wires to which the thermostats 6 are attached are the first winding wire 221a and the third winding wire 223a.

[0063] The electric motor 1 further comprises one or more first sub-winding wires 221b forming the first phase, one or more second sub-winding wires 222b forming the second phase, and one or more third sub-winding wires 223b forming the third phase.

[0064] The meanings of the one or more first sub-winding wires 221b and the one or more second sub-winding wires 222b are as stated above. One or more third sub-winding wires 223b are one or more winding wires that form the same phase as that of the third winding wire 223a and to which neither the thermistor 5 nor a thermostat 6 is attached.

[0065] The one or more first sub-winding wires 221b, together with the first winding wire 221a, form a series of winding wires that are continuous in the circumferential direction of the stator core 21. In other words, the first winding wire 221a and the one or more first sub-winding wires 221b are arranged continuously in the circumferential direction of the stator core 21 and form a first row. Furthermore, the first winding wire 221a is arranged in the center of the first row.

[0066] The one or more second sub-winding wires 222b, together with the second winding wire 222a, form a series of winding wires that are continuous in the circumferential direction of the stator core 21. In other words, the second winding wire 222a and the one or more second sub-winding wires 222b are arranged continuously in the circumferential direction of the stator core 21 and form a second row. Furthermore, the second winding wire 222a is arranged in the center of the second row.

[0067] The one or more third sub-winding wires 223b, together with the third winding wire 223a, form a row of winding wires that are continuous in the circumferential direction of the stator core 21. In other words, the third winding wire 223a and the one or more third sub-winding wires 223b are arranged continuously in the circumferential direction of the stator core 21 and form a third row. Furthermore, the third winding wire 223a is arranged in the center of the third row.

[0068] Here, the center means that an equal number of third sub-winding wires 223b are arranged on both sides of the third winding wire 223a in the circumferential direction of the stator core 21. However, the number of third sub-winding wires 223b arranged on both sides of the third winding wire 223a 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 the third winding wire 223a and the third sub-winding wires 223b is four, the third winding wire 223a can be any of the two winding wires 22 closer to the center. This case is also included in the concept that the third winding wire 223a is arranged in the center of the third row.

[0069] The two thermostats 6 are connected in series to the thermistor 5. Note that the two thermostats 6 are also connected in series. The temperatures of the first winding wire 221a, the second winding wire 222a, and the third winding wire 223a are measured based on the combined resistance of the resistance of the thermistor 5 and the resistances of the two thermostats 6.

[0070] When a value of the composite resistance is less than the first reference value R1 [°C], the value of the composite resistance is the same as the resistance of the thermistor 5. One reason for this is that the resistance of the thermostat 6 is 0 [Ω] unless the resistance is infinite. Therefore, when the value of the composite resistance is less than the first reference value R1 [Ω], the temperature of the second winding wire 222a can be measured based on the value of the composite resistance.

[0071] However, if the value of the composite resistance is less than or equal to the second reference value R2 [Ω], the temperature of the second winding wire 222a becomes greater than or equal to the predetermined temperature T [°C]. In other words, the second winding wire 222a is overheated. In this case, the power supply to the electric motor 1 may be interrupted.

[0072] In this embodiment, the second winding 222a, to which the thermistor 5 is attached, is arranged in the center of the second row. Therefore, when only the winding wire 22 constituting the second phase is overheated, it is possible to detect this overheating more reliably.

[0073] When the value of the composite resistance is greater than or equal to the first reference value R1 [Ω], that is, when the value becomes infinite, a temperature of at least one of the two thermostats 6 is greater than or equal to the predetermined temperature T [°C]. In other words, at least one of the first winding wire 221a and the third winding wire 223a is overheated. In this case, the power supply to the electric motor 1 may be interrupted.

[0074] In this embodiment, the first winding wire 221a and the third winding wire 223a, each of which has a thermostat 6 mounted thereon, are mounted in the center of the first row and the center of the third row, respectively. Therefore, when only the winding wire 22 constituting the first phase is overheated, or when only the winding wire 22 constituting the third phase is overheated, it is possible to detect this overheating more reliably. Fifth embodiment

[0075] Next, a description will be given of the controller that issues an alarm when a temperature detected by the electric motor 1 exceeds a predetermined temperature. The controller is, for example, a controller that controls the electric motor 1. The electric motor 1 is at least any one of the electric motors 1 described in Embodiments 1 to 4 described above.

[0076] Fig. 7 is a block diagram showing an example of the hardware configuration of the controller. The controller 10 is, for example, a numerical controller that controls an industrial machine. The controller 10 can be a computer such as a personal computer (PC), a server, or a tablet terminal.

[0077] The controller 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.

[0078] The hardware processor 11 is a processor that controls the entire controller according to a system program. The hardware processor 11 reads a 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 central processing unit (CPU) or an electronic circuit.

[0079] Bus 12 is a communication path that connects the respective hardware elements in the controller 10. The respective hardware elements in the controller 10 exchange data via bus 12.

[0080] The ROM 13 is a storage device that stores a system program for controlling the entire controller 10. The ROM 13 is a computer-readable storage medium.

[0081] RAM 14 is a memory device that temporarily stores various data. RAM 14 acts as a work area for processing various data by hardware processor 11.

[0082] Non-volatile memory 15 is a storage device that retains data even when controller 10 is turned off and power is not applied to controller 10. Non-volatile memory 15 is a computer-readable storage medium. Non-volatile memory 15 is embodied, for example, as a battery-backed memory or a solid-state drive (SSD).

[0083] The interface 16 connects the bus 12 and the electric motor 1. The controller 10 exchanges data with the electric motor 1 via the interface 16.

[0084] Fig. 8 is a block diagram showing an example of functions of the controller 10. The controller 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 implemented, 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.

[0085] For example, the control unit 101 controls the operation of the electric motor 1 based on an operation program stored in a storage unit (not shown).

[0086] 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, for example, to the first winding wire 221a wound around the stator core 21 of the electric motor 1 and constituting the first phase. The thermostat 6 is attached to the second winding wire 222a wound around the stator core 21 and constituting the second phase, different from the first phase. Furthermore, the thermostat 6 is connected in series to the thermistor 5.

[0087] The output unit 103 outputs an alarm when a value of the composite resistance detected by the detection unit 102 becomes greater than or equal to the first reference value or less than or equal to the second reference value. For example, the output unit 103 outputs an alarm to a display device (not shown) included in the controller 10. The output unit 103 may output the alarm using a rotating light connected to the controller 10.

[0088] Moreover, the control unit 101 stops the operation of the electric motor 1 when the value of the composite resistance detected by the detection unit 102 becomes greater than or equal to the first reference value or less than or equal to the second reference value.

[0089] Fig.9 is a flowchart showing an example of the processing executed by the controller 10. First, the control unit 101 of the controller 10 controls the electric motor 1 (step S1).

[0090] Next, the detection unit 102 detects the combined resistance of the thermistor 5 and the thermostat 6 (step S2). Then, the detection unit 102 determines whether the combined resistance value satisfies a predetermined condition (step S3). Specifically, the detection unit 102 determines whether the combined resistance value is greater than or equal to the first reference value or less than or equal to the second reference value.

[0091] If the composite resistance does not satisfy the predetermined condition (No in step S3), the detection unit 102 continues the detection of the composite resistance.

[0092] If the combined resistance meets the predetermined condition (Yes in step S3), the output unit 103 gives an alarm (step S4). Furthermore, the control unit 101 stops the operation of the electric motor 1 (step S5), thereby ending the process.

[0093] As described above, the electric motor 1 includes a stator core 21, a first winding wire 221a wound around the stator core 21 and forming a first phase, a second winding wire 222a wound around the stator core 21 and forming a second phase different from the first phase, a thermistor 5 attached to the first winding wire 221a, and a thermostat 6 connected in series to the thermistor 5 and attached to the second winding wire 222a.

[0094] Therefore, overheating can be detected even if only one of the first winding wire 221a and the second winding wire 222a is overheated. And since the thermistor 5 and the thermostat 6 are connected in series, the wiring can be prevented from becoming complicated.

[0095] In addition, the electric motor 1 further includes the one or more first sub-winding wires 221b constituting the first phase, wherein the first winding wire 221a and the one or more first sub-winding wires 221b are continuously arranged in the circumferential direction of the stator core 21 and form the first row, and the first winding wire 221a is arranged in the center of the first row. In addition, the electric motor 1 further includes the one or more second sub-winding wires 222b constituting the second phase, wherein the second winding wire 222a and the one or more second sub-winding wires 222b are continuously arranged in the circumferential direction of the stator core 21 and form the second row, and the second winding wire 222a is arranged in the center of the second row.

[0096] For example, if only the winding wire 22 constituting the first phase is overheated, the temperature in the center of the first row becomes the highest. On the other hand, the temperatures near the two ends of the first row become relatively low due to the influence of the ambient temperature. For this reason, by disposing the first winding wire 221a in the center of the first row, in the event of overheating of the winding wire 22 constituting the first phase, it is possible to detect this overheating at an early stage. Likewise, by disposing the second winding wire 222a in the center of the second row, in the event of overheating of the winding wire 22 constituting the second phase, it is possible to detect this overheating at an early stage.

[0097] In addition, the controller 10 includes the detection unit 102 that detects the composite resistance of the resistance of the thermistor 5 attached to the first winding wire 221a wound around the stator core 21 and constituting the first phase, and the resistance of the thermostat 6 attached to the second winding wire 222a wound around the stator core 21 and constituting the second phase different from the first phase and connected in series to the thermistor 5, and the output unit 103 that outputs an alarm when the value of the composite resistance detected by the detection unit 102 becomes greater than or equal to the first reference value or less than or equal to the second reference value.

[0098] Therefore, the controller 10 can detect overheating even if only one of the first winding wire 221a and the second winding wire 222a is overheated. Furthermore, the controller 10 can notify an operator at an early stage that the detection unit 102 has detected overheating.

[0099] The present disclosure has been described in detail above, but is not limited to these embodiments. Thus, various additions, substitutions, modifications, partial omissions, and so on can be made to these embodiments without departing from the gist of the disclosure or the spirit of the disclosure derived from the contents described in the claims and their equivalents. Furthermore, these embodiments can be implemented in combination. For example, the order of operations and the order of processes in these embodiments are provided as examples, but are not limited thereto. Furthermore, numerical values ​​or formulas applied to these embodiments, if any, are also not limited thereto.

[0100] With regard to the above-described embodiments and their modifications, supplementary remarks are disclosed below. Supplementary Note 1

[0101] An electric motor includes a stator core; a first winding wire wound around the stator core and forming a first phase; a second winding wire wound around the stator core and forming a second phase different from the first phase; a thermistor attached to the first winding wire; and a thermostat connected in series to the thermistor and attached to the second winding wire. Supplementary Note 2

[0102] The electric motor according to Supplementary Note 1 further comprises one or more first sub-winding wires constituting the first phase, wherein the first winding wire and the one or more first sub-winding wires are continuously arranged in a circumferential direction of the stator core and form a first row, and the first winding wire is arranged in the center of the first row. Supplementary Note 3

[0103] The electric motor according to Supplementary Note 1 or 2 further comprises one or more second sub-winding wires constituting the second phase, wherein the second winding wire and the one or more second sub-winding wires are continuously arranged in the circumferential direction of the stator core and form a second row, and the second winding wire is arranged in the center of the second row. Supplementary Note 4

[0104] A control unit has a detection unit configured to detect a composite resistor composed of a resistor of a thermistor attached to a first winding wire wound around a stator core and forming a first phase, and a resistor of a thermostat attached to a second winding wire wound around the stator core and forming a second phase different from the first phase and connected in series to the thermistor; and an output unit configured to output an alarm when a value of the composite resistor detected by the detection unit becomes greater than or equal to a first reference value or less than or equal to a second reference value. EXPLANATION OF REFERENCE SIGNS 1 ELECTRIC MOTOR 2 STATOR 21 STATOR CORE 211 SHAFT 212 TEETH 22 WINDING WIRE 221a FIRST WINDING WIRE 221b FIRST SECONDARY WINDING WIRE 222a SECOND WINDING WIRE 222b Second secondary winding wire 223a THIRD WINDING WIRE 223b THIRD SUBSCRIBE WINDING WIRE 3 ROTOR 31 PERMANENT MAGNET 5 THERMISTOR 6 THERMOSTAT 10 CONTROL 11 HARDWARE PROCESSOR 12 BUS 13 ROM 14 RAM 15 NON-VOLATILE MEMORY 16 INTERFACE 102 DETECTION UNIT 103 OUTPUT UNIT QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2018 / 021043

[0003]

Claims

[1] Electric motor, comprising a stator core; a first winding wire wound around the stator core and forming a first phase; a second winding wire wound around the stator core and forming a second phase different from the first phase; a thermistor attached to the first winding wire; and a thermostat connected in series to the thermistor and attached to the second winding wire. [2] The electric motor according to claim 1, further comprising one or more first sub-winding wires constituting the first phase, wherein the first winding wire and the one or more first sub-winding wires are continuously arranged in a circumferential direction of the stator core and form a first row, and the first winding wire is arranged in the center of the first row. [3] The electric motor according to claim 1 or 2, further comprising one or more second sub-winding wires constituting the second phase, wherein the second winding wire and the one or more second sub-winding wires are continuously arranged in the circumferential direction of the stator core and form a second row, and the second winding wire is arranged in the center of the second row. [4] Control, comprising a detection unit configured to detect a composite resistance of a resistance of a thermistor mounted on a first winding wire wound around a stator core and forming a first phase, and a resistance of a thermostat mounted on a second winding wire wound around the stator core and forming a second phase different from the first phase, and connected in series to the thermistor; and an output unit configured to output an alarm when a value of the composite resistance detected by the detection unit becomes greater than or equal to a first reference value or less than or equal to a second reference value.

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