Control device for an electric motor and braking device

Abstract

Control device for an electric motor of a vehicle, the control device comprising: a control board (20a) which is arranged to control the drive of an electric motor (11), a first temperature detecting section (23) arranged on the control board (20a), and a second temperature detection section (24) arranged on the control board (20a), wherein the first temperature detection section (23) and the second temperature detection section (24) are each arranged on the control board (20a) at positions that differ in the temperature change tendency, characterized in that the control device for the electric motor is arranged to estimate a temperature of the electric motor (11) on the basis of an ambient temperature (43) obtained from the output signals of the first and second temperature detecting sections (23, 24), the output signals being in a temperature change tendency in a first temperature (41) obtained by the first temperature detecting section (23), and a temperature change tendency in a second temperature (42) obtained by the second temperature detecting section (24), wherein the ambient temperature (43) is obtained during an interval (B) in which the vehicle to which the electric motor control device is attached stops and an ignition is turned off, while the energization of the electric motor (11) is interrupted and while the energization of the electric motor control device is continued.

Description

TECHNICAL FIELD

[0001] The invention relates to a device for controlling an electric motor and a braking device with an electric motor. STATE OF THE ART

[0002] For example, Patent Literature 1 discloses a control device of an electric power steering apparatus which estimates the motor winding temperature from the terminal-to-terminal voltage in a motor and a motor current detection value, and then protects the motor temperature based on the motor winding temperature. CITATION LISTPATENT LITERATURE

[0003] PTL 1: Unexamined publication of Japanese patent application (Kokai) JP H10 - 100 913 A

[0004] DE 10 2016 217 674 A1 is prior art, which discloses the preamble of claim 1. JP 2017-210 031 A and DE 197 10 890 A1 are further prior art. SUMMARY OF THE INVENTION TECHNICAL PROBLEM

[0005] According to the temperature estimation method disclosed in Patent Literature 1, it is necessary to measure the terminal-to-terminal resistance in the motor at the reference temperature for each product and store the measured values ​​in a non-volatile memory section. Such a method leads to an increase in the number of steps in the manufacturing process and thus to an increase in manufacturing costs. SOLUTION TO THE PROBLEM

[0006] The object of the invention is to provide an apparatus for controlling an electric motor which is capable of estimating the temperature of an electric motor while limiting an increase in manufacturing costs, as well as a braking device.

[0007] The invention is defined by the independent claims.

[0008] The invention provides temperature sensing sections arranged on a control board that controls the drive of an electric motor at at least two locations that differ in the temperature change tendency.

[0009] The invention makes it possible to estimate the temperature of the electric motor while limiting an increase in manufacturing costs. BRIEF DESCRIPTION OF THE ILLUSTRATIONS Fig. 1 is a block diagram showing an essential part of a braking device according to a first embodiment of the invention. Fig. Figure 2 shows an essential part of a motor control device and an electric motor in the braking device of Fig. 1. Fig. 3 is a graph showing the temporal changes of the temperatures detected by the first and second temperature detecting sections in the braking device of Fig. 1 with the ambient temperature and the engine temperature. Fig. 4 is a block diagram showing a main part of a braking device according to a second embodiment of the invention. DESCRIPTION OF THE EMBODIMENTS

[0010] Embodiments of the invention are discussed with reference to the accompanying drawings.

[0011] Fig. 1 is a block diagram showing an essential part of an electric braking device 1 according to a first embodiment of the invention. Fig. Fig. 2 is a block diagram showing an essential part of a motor control device 20 in the electric brake device 1 in Fig. 1. The electric braking device 1 is a braking device that applies a braking force to each wheel by compressing a disc D that rotates with each wheel (not shown) of a vehicle. As shown in Fig. 1, the electric braking device 1 includes a braking mechanism 10 associated with each wheel, which is braked by each corresponding electric braking device 1. The braking mechanism 10 includes brake pads 2 and 3 pressed against the disc D, and a piston 4 that moves the brake pads 2 and 3. The braking mechanism 10 further includes an electric motor 11 and a rotation-to-linear motion conversion mechanism 12 that converts the rotation of the electric motor 11 into linear motion and transmits the linear motion to the piston 4.

[0012] Since the electric braking device 1 comprises the braking mechanism 10 with respect to each wheel that, as mentioned, is braked by the electric braking device 1, typically a plurality of braking mechanisms 10 are provided (e.g., four braking mechanisms 10 if the vehicle is a four-wheel vehicle). For clarity of illustration and description, the electric braking device 1 will be discussed here primarily with respect to one of the braking mechanisms 10 and its components. The aspects discussed with respect to one braking mechanism 10 are applicable to all other braking mechanisms unless clearly stated otherwise.

[0013] The electric braking device 1 further comprises a motor control device 20 which controls the operation of the electric motor 11. In Fig. 1, the electric motor 11, the rotational-linear motion conversion mechanism 12, and the control device 20 are shown outside a brake caliper 5 as separate blocks from the brake caliper 5. The figure shows the electric motor 11, the rotational-linear motion conversion mechanism 12, and the control device 20 merely as functional blocks in a schematic manner and is not intended to limit the spatial arrangement of the components 11, 12, and 20. Generally, in the electric braking device 1, the electric motor 11 and the rotational-linear motion conversion mechanism 12 are arranged together with the piston 4 in the brake caliper 5. Alternatively, the control device 20 is also arranged in the brake caliper 5.

[0014] The braking mechanism 10 according to the first embodiment may comprise an arbitrary component (e.g., a deceleration mechanism that decelerates the rotation of the electric motor 11) suitable as a braking device that applies a braking force to each wheel by compressing the disc D rotating with the wheel.

[0015] As in Fig. 2, the motor control device 20 comprises a motor drive section 21 and a controller 26 mounted on a control board 20a associated with the motor control device 20 (in Fig. 2, solid lines indicate the motor control device 20 and the control board 20a included in the motor control device 20. In the electric brake device 1, the electric motor 11 comprises, for example, a three-phase synchronous motor. Accordingly, the motor drive section 21 includes a three-phase inverter device that converts direct current supplied to the motor drive section 21 by a power source 37 into three-phase alternating current and outputs the three-phase alternating current to the electric motor 11. The controller 26 outputs to the motor drive section 21 a switch control signal 31 for controlling the ON / OFF switching of a semiconductor switching element (e.g., a MOS-FET) 22 constituting the three-phase inverter device. The motor drive section 21 controls the drive of the electric motor 11 by pulse width modulation (PWM) in accordance with the switch control signal 31.

[0016] In the electric brake device 1, the electric motor 11 is provided with a rotational position detection section 38. A rotational position signal 36 corresponding to a rotational position of the electric motor 11 is input from the rotational position detection section 38 to the controller 26 of the motor control device 20. A current signal 32 corresponding to the motor drive current (winding current) of each phase is also input from the motor drive section 21 to the controller 26. The controller 26 is configured to be capable of implementing vector control of the rotational speed of the electric motor 11 in accordance with the above information.

[0017] A first temperature sensing section 23 and a second temperature sensing section 24, which include, for example, thermostats, are mounted on the control board 20a of the engine control device 20. The temperature signals 33 and 34 are input to the controller 26. The temperature signals 33 and 34 correspond to temperatures measured by the first and second temperature sensing sections 23 and 24. The first temperature sensing section 23 is arranged in a heat-generating section on the control board 20a of the engine control device 20. The second temperature sensing section 24 is arranged in a non-heat-generating section on the control board 20a of the engine control device 20 at a position remote from the heat-generating section.

[0018] The heat-generating section is a specific or local area on the control board 20'a comprising a position where a component that generates heat during operation is mounted. The component is typically a component that generates a relatively large amount of heat. The non-heat-generating section is a specific or local area on the control board 20a where a component that generates heat during operation is not mounted. When a component is mounted on the non-heat-generating section, the amount of heat generated by the component is relatively small.

[0019] One of the typical heat-generating sections in the motor control device 20 is the motor drive section 21, or more precisely, a specific or local area that includes the semiconductor switching element 22 as a heat-generating component. Fig. 2, the first temperature sensing section 23 is arranged in the immediate vicinity of the semiconductor switching element 22. In this sense, Fig. 2 shows an example in which the first temperature sensing section 23 is arranged in the heat-generating section. However, the heat-generating section of the engine control device 20 is not limited to the Fig. 2. For example, the area including the regulator 26 can be regarded as a heat-generating portion. Furthermore, when a pre-driver (not shown) for the inverter device is mounted on the control board 20a, an area including the pre-driver can also be regarded as a heat-generating portion. According to the invention, the location where the first temperature sensing portion 23 is disposed is properly determined, taking into account the component mounting conditions on the control board 20a and the like. The first temperature sensing portion 23 can be disposed near the above-mentioned heat-generating portions.

[0020] In the Fig. In the example shown in Fig. 2, the second temperature sensing section 24 is disposed in a peripheral region of the control board 20a of the motor control device 20. In this example, it is assumed that the specific or local region where the second temperature sensing section 24 is disposed is a non-heat-generating section, that is, no component that generates heat during operation, or preferably no component at all, is mounted on the specific region. Moreover, the specific region where the second temperature sensing section 24 is disposed is located away from all heat-generating sections, including the motor drive section 21, the controller 26, and the like, and is preferably the farthest away from all heat-generating sections.

[0021] The control board 20a of the motor control device 20 generally increases in temperature due to the operation of the motor control device 20. The resulting temperature is not uniform across the control board 20a. The temperature distribution during the operation of the motor control device 20 is locally uneven, depending on the heat generation characteristics of the components mounted on the control board 20a at their respective positions or other factors. With such a temperature distribution, the heat-generating portions and areas near the heat-generating portions are areas indicating a relatively high temperature, and the non-heat-generating portions and areas away from the heat-generating portions are areas indicating a relatively low temperature.

[0022] The controller 26 may be connected to a vehicle data bus, not shown, to thereby send and receive a variety of information, including information necessary for engine drive control and temperature estimation, discussed later, to and from each other and / or to another electronic control unit (ECU) by communicating over the vehicle data bus.

[0023] The controller 26 is preferably implemented as a well-known microcomputer system equipped with a CPU (central processing unit), a ROM (read-only memory), a RAM (random access memory), an I / O (input / output) interface, and the like. Instead, the controller 26 may be partially or entirely composed of freely selected, suitable hardware or software, or a combination of hardware and software, as long as the controller 26 is capable of implementing the motor drive control and temperature estimation, which will be discussed in detail later.

[0024] In the electric braking device 1 thus constructed, the rotation of the electric motor 11, driven by the motor drive section 21 under the control of the controller 26, is converted into a linear motion by the rotational-linear motion conversion mechanism 12 of the braking mechanism 10. The linear motion transmits thrust to the piston 4 and causes the brake pads 2 and 3 moved by the piston 4 to press against the disc D, thereby generating a braking force.

[0025] In the following discussion, the estimation of the temperature of the electric motor 11 (ie the winding temperature of the electric motor 11) in the electric braking device 1 will be described with reference to Fig. 3 in addition to the Fig. 1 and Fig. 2. The controller 26 of the motor control device 20 is either configured to previously store a temperature coefficient α of the winding material of the electric motor 11 and a torque constant of the electric motor 11, or is capable of obtaining the temperature coefficient α of the winding material of the electric motor 11 and the torque constant of the electric motor 11 from another electronic control device installed in the vehicle as needed.

[0026] Fig. 3 is a graph showing a time change of the temperature 41 obtained from the first temperature detecting section 23 and the temperature 42 obtained from the second temperature detecting section 24, assuming the ambient temperature 43 and the winding temperature 40 of the electric motor 11.

[0027] In the electric braking device 1, the initial resistance Ri of the winding of the electric motor 11 is first determined as shown below. Fig. Interval A shown in Figure 3 is a state in which the engine control device 20 is operating. During interval A, the temperatures 41 and 42 of the control board 20a of the engine control device 20 are generally higher than the ambient temperature 43 due to the heat generated by the operation of the components mounted on the control board 20a. According to a Fig. In the example shown in Figure 3, it is assumed that the winding temperature 40 of the electric motor 11 is higher than the temperatures 41 and 42 of the control board 20a. Since the first temperature sensing section 23 is arranged in the heat-generating section on the control board 20a and the second temperature sensing section 24 is arranged in the non-heat-generating section on the control board 20a, the temperature 41 is higher than the temperature 42.

[0028] At a time P, the vehicle stops, and an ignition is turned off. During an interval B after time P, the operation of the motor drive section 21, and thus the excitation of the electric motor 11, is interrupted until an initial resistance is reached, while the excitation of the motor control device 20 itself continues. Since the operation of the motor drive section 21 is interrupted, it is assumed that the temperatures 41 and 42 are lowered toward the ambient temperature 43, and at the same time, the winding temperature of the electric motor 11, whose excitation is interrupted, is also lowered toward the ambient temperature 43.

[0029] The controller 26 continuously monitors the difference between the temperatures 41 and 42 during the interval B and determines whether the difference becomes equal to or smaller than a predetermined threshold. The predetermined threshold is set to a value such that the temperatures 41 and 42 are considered to be substantially the same (e.g., within an error margin) when the difference between the temperatures 41 and 42 becomes equal to or smaller than the threshold. If the temperature 41 obtained from the first temperature detecting section 23 and the temperature 42 obtained from the second temperature detecting section 24 agree with each other when the first and second temperature detecting sections 23 and 24 are arranged at two positions that differ in temperature change tendency, this means that the temperatures 41 and 42 both reach the ambient temperature 43.This leads to the assumption that the winding temperature of the electric motor 11 also reaches the ambient temperature 43 after a sufficient period of time before reaching the ambient temperature 43.

[0030] At this point the following equation is established. Temperature 41=Temperature 42=Ambient temperature 43=Winding temperature 40of the electric motor 11

[0031] Referring to the diagram in Fig. 3, the controller 26 determines that the difference between the temperature 41 and the temperature 42 at a time in a range C is equal to or less than the predetermined threshold. The controller 26 then performs the following operation to determine the initial resistance. In this operation, the controller 26 controls the motor drive section 21 so that the q-axis current of the electric motor 11 is set to zero and only the d-axis (hereinafter also simply referred to as d-axis excitation) is excited by the switch control signal 31, thereby exciting the winding current without rotating the electric motor 11. The controller 26 calculates the initial resistance Ri of the winding of the electric motor 11 according to the following equation (2) based on the input winding current (current signal 32). Ri=Inverter voltage×OPERATION / Winding current where the inverter voltage is the source voltage of the power source 37; DUTY is a duty ratio in the ON / OFF operation of the semiconductor switching element 22 of the motor drive section 21; and the winding current is a current value corresponding to the current signal 32.

[0032] The controller 26 stores the calculated initial resistance Ri and the initial temperature Ti, expressed by equation (1), in a non-volatile memory section. The non-volatile memory section is provided to the controller 26 or another electronic control device installed in the vehicle. After the initial resistance determination process is completed, the excitation of the motor control device 20 is interrupted at a time Q.

[0033] The winding temperature of the electric motor 11 is estimated as described below at an arbitrary time after the initial resistance conservation process has been performed.

[0034] First, the resistance Rc of the winding at the freely chosen time (hereinafter also referred to as current resistance Rc) is calculated according to equation (3). Rc=(Inverter voltage-torque constant×speed)×OPERATION / winding current where the inverter voltage is the source voltage of the power source 37; the DUTY is the duty ratio in the ON / OFF operation of the semiconductor switching element 22 of the motor driving section 21; the winding current is a current value corresponding to the current signal 32; the torque constant is a torque constant specific to the electric motor 11; and the rotational speed is the rotational speed of the electric motor 11 at the point of estimation obtained based on the rotational position signal 36.

[0035] It goes without saying that when the rotation speed is set to zero, equation (3) is applicable to a situation where the rotation of the electric motor 11 is suspended. When the current resistance Rc is to be obtained while the rotation of the electric motor 11 is suspended, for example, in a situation where the vehicle is stopped, it is preferable that the current value of the winding current be obtained by driving the electric motor 11 by the excitation of the d-axis without rotating the electric motor 11 in a similar manner to when performing the operation of obtaining the initial resistance.

[0036] The controller 26 then obtains the estimated current winding temperature Tc of the electric motor 11 according to the following equation (4) based on the calculated current resistance Rc of the winding, the stored initial resistance Ri of the winding and the stored initial temperature Ti of the winding, as well as the stored temperature coefficient α of the winding material. Tc=(Rc−Ri) / (α×Ri)+Ti

[0037] The following is an example of the estimated current winding temperature Tc under the condition that the winding material is copper (α=0.393% / °C) and that the initial temperature Ti is 25°C. When the inverter voltage and duty ratio are 12 V and 50%, respectively, and the winding current at this time is 30 A, the initial resistance Ri of the winding during operation to obtain the initial resistance is 0.2 Ω according to equation (2). At the time of temperature estimation, when the inverter voltage, duty ratio, and a counter electromotive force of the electric motor 11 (i.e., torque constant × rotational speed) are 12 V, 100%, and 3 V, respectively, and the winding current at this time is 30 A, the current resistance Rc of the winding is 0.3 Ω according to equation (3). In such a case, the estimated current temperature Tc of the winding is approximately 152°C according to equation (4).

[0038] The initial resistance acquisition process can preferably be performed once during an initial phase or more than once, as needed, during the vehicle's life cycle. If the initial resistance acquisition process is performed more than once, the last initial resistance Ri and the last initial temperature Ti can be used to estimate the current temperature Tc of the winding. Alternatively, it is also possible, for example, to average a plurality of initial resistances Ri and initial temperatures Ti to obtain corresponding representative values, thus using the representative values.

[0039] Two temperature sensing sections, namely the first and second temperature sensing sections 23 and 24, are arranged on the control board 20a of the motor control device 20. However, according to the invention, the temperature sensing sections may include temperature sensing sections each corresponding to two or more sections that differ in temperature change tendency (e.g., two or more heat-generating sections and / or two or more non-heat-generating sections).

[0040] In conventional braking devices, a screw thermistor is attached to the casing of an electric motor to estimate the winding temperature of the electric motor. The winding temperature of the electric motor is estimated from the casing temperature obtained by the thermistor, a constant obtained during heat generation / dissipation, an integrated value of the winding current, and the like. The above method has the problem that the number of components that need to be arranged in a limited space such as a wheel house is increased, so it is necessary to provide a physical connection point for temperature measurement in a location such as an unsprung area that must meet high vibration requirements, and that complicated logic is required to estimate the temperature (winding temperature) of the electric motor from the temperature near the electric motor.

[0041] For example, the method described in Patent Literature 1 requires that the initial winding resistance of an electric motor must be measured in advance for each product using a sensitive low-order resistance measuring device, which results in an increase in the number of steps of the manufacturing process and thus an increase in manufacturing costs.

[0042] Unlike Patent Literature 1, the brake device (electric brake device 1) and the motor control device (motor control device 20) according to the present invention include the temperature detection sections (first and second temperature detection sections 23 and 24) at at least two positions that differ in temperature change tendency on the control board 20a that controls the drive of the electric motor 11. Therefore, the present invention does not require a dedicated temperature sensor to be directly mounted near the electric motor. Furthermore, the present invention enables a more direct estimation of the temperature (winding temperature) of the electric motor 11, taking into account a change caused by the drive of the electric motor 11, without requiring complicated logic for estimating the temperature (winding temperature) of the electric motor from the temperature near the electric motor.The invention thus makes it possible to estimate the temperature (winding temperature) of the electric motor 11 with high accuracy using a simpler and more compact logic.

[0043] The braking device (electric braking device 1) and the motor control device (motor control device 20) according to the present embodiment estimate the temperature of the electric motor 11 depending on the ambient temperature obtained based on the outputs of the temperature detection sections (first and second temperature detection sections 23 and 24). This eliminates the need for pre-measuring the winding resistance of the electric motor for each product by using a sensitive measuring device for measuring the low-order resistance during the manufacturing process of the electric braking device 1 and / or the motor control device 20, thereby limiting or solving an increase in the number of steps of the manufacturing process and thus an increase in manufacturing costs.

[0044] In the braking device (electric braking device 1) and the motor control device (motor control device 20) according to the present embodiment, the first temperature detecting section 23 is arranged in the heat-generating section on the control board 20a or in the vicinity of the heat-generating section, and the second temperature detecting section 24 is arranged in the non-heat-generating section of the control board 20a or at a location remote from the heat-generating section of the control board 20a. This makes it possible to detect the ambient temperature (ieThe initial temperature of the electric motor 11 is estimated with high accuracy, and thus the initial temperature (winding temperature) of the electric motor 11 is estimated as a value such that the temperatures obtained from the first and second temperature detection sections 23 and 24 converge over time, enabling an accurate estimation of the current temperature (winding temperature) of the electric motor 11. This makes it possible to reliably perform an operation for protecting the electric motor 11, which is required at high temperatures such as during gradual power reduction or the like.

[0045] In the braking device (electric braking device 1) and the motor control device (motor control device 20) according to the present embodiment, the winding resistance of the electric motor 11 is measured without rotating the electric motor 11 due to the d-axis excitation when the vehicle is stopped (including the situation in which the initial resistance acquisition process is performed). In this way, it is possible to measure the winding resistance (e.g., the initial resistance Ri and the actual resistance Rc resulting from the vehicle stop) without causing discomfort to the vehicle user and with high accuracy (e.g., without being affected by a constant torque change).

[0046] In the following, a braking device 60 according to a second embodiment of the invention will be described with reference to Fig.4, focusing on the differences from the first embodiment. Components and portions similar to or corresponding to those of the first embodiment are denoted by the same terms and reference numerals as in the first embodiment.

[0047] The braking device 60 is a hydraulic braking device that applies braking force to each wheel by compressing a disc D that rotates with each wheel (not shown) of a vehicle. The braking device 60 includes a braking mechanism 61 with brake pads 2 and 3 pressed against the disc D, and a piston 4 slidably disposed within an inner periphery of a cylinder 66 of a caliper 5, which moves the brake pads 2 and 3. The braking mechanism 61 is provided for each wheel braked by the braking device 60.

[0048] The braking device 60 further comprises a master cylinder 67, which generates hydraulic pressure provided in the cylinder 66 of the caliper 5, and an electric booster device 70 acting on the master cylinder 67. The electric booster device 70 comprises an electric motor 11, which drives a booster piston (not shown) capable of adjusting the hydraulic pressure in the master cylinder 67, and a rotation-to-linear motion conversion mechanism 72, which converts the rotation of the electric motor 11 into linear motion and transmits the linear motion to the booster piston. The electric booster device 70 is capable of implementing various braking controls, such asregenerative cooperative control, brake assist and automatic brake, using the electric motor 11 driven by a motor control device 20, which will be described later in connection with the depression of a brake pedal, not shown, or independently of the operation of the brake pedal.

[0049] The braking device 60 includes the motor control device 20, which controls the operation of the electric motor 11. The electric motor 11, driven under the drive control of the motor control device 20, is used to generate hydraulic pressure in the master cylinder 67 and thus to generate the braking force in the brake mechanism 61 of each wheel.

[0050] The electric motor 11 of the braking device 60 is similar to the corresponding element of the electric braking device 1 of the first embodiment. The motor control device 20 in the braking device 60 functions similarly to the motor control device 20 of the electric brake 1 of the first embodiment with regard to driving the electric motor 11.

[0051] With the configuration discussed above, the braking device 60 and the motor control device 20 provide the same operation and the same advantageous effects as those discussed above with respect to the electric braking device 1 and the motor control device according to the first embodiment.

[0052] The control device 20 of the electric motor 11 according to the invention was discussed with reference to the braking system of the vehicle. However, the device for controlling the electric motor according to the invention is not limited to that discussed above. On the contrary, the device for controlling the electric motor according to the invention is applicable, for example, to other systems in the vehicle, such as an electric drive device and an electric power steering system, and further to other devices that are not installed in the vehicle. The invention is also applicable to systems in which the electric motor 11 and the control device 20 are arranged at a distance from each other. LIST OF REFERENCE SYMBOLS 1 Electric braking device (braking device) 2, 3 brake pad (brake element) 4 pistons 11 Electric motor 10, 61 Brake mechanism 20 Engine control device 20a control board 23 First temperature detection section (temperature detection section) 24 Second temperature detection section 43 Ambient temperature D Disc (braked element)

Claims

[1] Control device for an electric motor of a vehicle, the control device comprising: a control board (20a) which is arranged to control the drive of an electric motor (11), a first temperature detecting section (23) arranged on the control board (20a), and a second temperature detection section (24) arranged on the control board (20a), wherein the first temperature detection section (23) and the second temperature detection section (24) are each arranged on the control board (20a) at positions that differ in the temperature change tendency, characterized by , that the control device for the electric motor is arranged to estimate a temperature of the electric motor (11) on the basis of an ambient temperature (43) obtained from the output signals of the first and second temperature detecting sections (23, 24), the output signals being in a temperature change tendency in a first temperature (41) obtained by the first temperature detecting section (23), and a temperature change tendency in a second temperature (42) obtained by the second temperature detecting section (24), wherein the ambient temperature (43) is obtained during an interval (B) in which the vehicle to which the electric motor control device is attached stops and an ignition is turned off, while the energization of the electric motor (11) is interrupted and while the energization of the electric motor control device is continued. [2] The electric motor control device according to claim 1, wherein the electric motor control device is configured to estimate the temperature of the electric motor (11) based on the ambient temperature (43) obtained from the output signals of the temperature detecting sections (23, 24) and to control the electric motor (11). [3] Braking device comprising: an electric motor (11) which is arranged to press a braking element (2, 3) against an element to be braked (D) in order to generate a braking force, and a control board (20a) which is arranged to control the drive of the electric motor (11), the control board (20a) comprising: a first temperature detection section (23) arranged on the control board (20a) and configured to detect a first temperature (41), and a second temperature detecting section (24) arranged on the control board (20a) at a position where a temperature differs in the tendency of change from the first temperature detected by the first temperature detecting section (23), wherein the control board (20a) is configured to estimate a temperature of the electric motor (11) based on an ambient temperature (43) obtained from the output signals of the first and second temperature detecting sections (23, 24), the output signals being in a temperature change tendency in a first temperature (41) obtained by the first temperature detecting section (23), and a temperature change tendency in a second temperature (42) obtained by the second temperature detecting section (24), wherein the ambient temperature (43) is obtained during an interval (B) in which the vehicle on which the electric motor control device is mounted stops and an ignition is turned off while the energization of the electric motor (11) is interrupted while the energization of the electric motor control device is continued. [4] Braking device according to claim 3, wherein the first temperature detecting section (23) is arranged in a heat-generating section of the control board (20a) or in the vicinity of the heat-generating section, and wherein the second temperature detecting section (24) is arranged in a non-heat generating section of the control board (20a) or at a position on the control board (20a) remote from the heat generating section.

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