Driving device and control method

Abstract

To provide a driving device capable of suppressing temperature rise of a heat source in a component which generates heat in a case of high-current driving of a driver part for increasing output torque from the driver part.SOLUTION: An embodiment of the invention includes: a driver part 3 for driving a load 8; a power conversion part 30 for supplying power to the driver part by converting power from a current source 2; a temperature detection part 11 for detecting a temperature nearby a heat source generating heat in the power conversion part or the driver part; and a control part 10 for controlling the power conversion part so as to output torque determined based on a command signal input from an input part 5 and the temperature acquired based on a detection result of the temperature detection part. The control part controls the power conversion part so as to output limited torque smaller than command torque corresponding to the command signal if the temperature acquired based on the detection result is in a limited state greater than a preset limit threshold value and less than a preset abnormal threshold value higher than the limit threshold value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drive device and a control method. [Background technology]

[0002] An electric vehicle has a motor for driving a load and a drive device for controlling the motor and the like (see, for example, Patent Document 1 and Patent Document 2).

[0003] In such electric vehicles, when starting off up a slope, for example, if the torque output from the motor is increased in response to user operation, if a high current flows through the motor at a low angular velocity, there is a problem that the temperature of the drive device or motor will rise too high. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-113676 A [Patent Document 2] JP 2014-168341 A Summary of the Invention [Problem to be solved by the invention]

[0005] Various aspects of the present invention aim to provide a drive device and a control method that are capable of suppressing the rise in temperature of the heat source of a component that generates heat when the drive unit is driven with a high current to increase the torque output from the drive unit. [Means for solving the problem]

[0006] Various aspects of the present invention are described below.

[0007] [1] A drive unit that drives a load; a power conversion unit that converts power from a current source and supplies the power to the drive unit; a temperature detection unit that detects a temperature in the vicinity of a heat source generated by the power conversion unit or the drive unit; a control unit that controls the power conversion unit so that a torque determined by a command signal input from a torque input unit and a temperature obtained based on a detection result of the temperature detection unit is output from the drive unit; and Equipped with The control unit is When the temperature obtained based on the detection result is equal to or higher than a preset limit threshold and is lower than a preset abnormality threshold higher than the limit threshold, the power conversion unit is controlled so that a limit torque smaller than a command torque corresponding to the command signal is output from the drive unit. A drive device characterized by:

[0008] [2] The control unit is When the temperature obtained based on the detection result is equal to or higher than the abnormality threshold, the power conversion unit is controlled so that the torque output from the drive unit becomes zero. The drive device according to the above [1].

[0009] [3] The control unit is When the temperature obtained based on the detection result is a normal state below the limit threshold, the power conversion unit is controlled so that a command torque corresponding to the command signal is output from the drive unit. The drive device according to the above [1] or [2],

[0010] [4] The temperature sensor further includes a storage unit configured to store a target limit torque table that associates a frequency of a current flowing through the drive unit with a target limit torque when the temperature obtained based on the detection result is the limit threshold value. The drive device according to any one of the above [1] to [3],

[0011] [5] When the control unit is in the restricted state, Acquire a frequency of a current flowing through the drive unit; The target limit torque table stored in the storage unit is referenced to set the limit torque so that the limit torque is equal to or greater than the target limit torque corresponding to the acquired frequency. The drive device according to [4] above.

[0012] [6] When the control unit is in the restricted state, calculating a temperature difference value by multiplying a value obtained by subtracting the limit threshold value from the temperature obtained based on the detection result by a positive adjustment coefficient; Acquire a frequency of a current flowing through the drive unit; calculating a target limit torque corresponding to the acquired frequency by referring to the target limit torque table stored in the storage unit; calculating a negative cut torque to be subtracted from the command torque by multiplying a value obtained by subtracting a current torque currently output by the drive unit from the calculated target limit torque by the temperature difference value; Calculating the limit torque by adding the negative cut torque to the command torque; The power conversion unit is controlled so that the limit torque is output from the drive unit. The drive device according to [4] above.

[0013] [7] In the target limit torque table, the target limit torque is set to increase as the frequency of the current flowing to the drive unit increases, and the target limit torque is set to decrease as the frequency of the current flowing to the drive unit decreases. The drive device according to any one of the above [4] to [6],

[0014] [8] The temperature obtained based on the detection result is a control estimated temperature obtained by the control unit, the storage unit stores a saturation temperature information table in which a combination of a current value flowing in the drive unit and a frequency of the current flowing in the drive unit is associated with a saturation temperature that is a maximum temperature at which the heat of the heat source is saturated; The control unit is A current value flowing in the drive unit is obtained, and a frequency of the current flowing in the drive unit is obtained; a step a of calculating a current saturation temperature of the heat source corresponding to a combination of the current value and the frequency by referring to the saturation temperature information table stored in the storage unit; A step c of calculating a current estimated heat source temperature by estimating the temperature of the heat source by using the current saturation temperature and a first coefficient; A step e of calculating a current estimated detection unit temperature by estimating a temperature in the vicinity of the heat source by using the current estimated heat source temperature and a second coefficient; a step f of acquiring an actual temperature detected by the temperature detection unit; a step g of calculating a temperature difference by subtracting the actual temperature from the current estimated detection unit temperature; a step h of calculating a temperature correction value by multiplying the temperature difference by a preset temperature correction coefficient; a step i of calculating an estimated control temperature by adding the temperature correction value to the current estimated heat source temperature, The current estimated heat source temperature in the step c is When the current saturation temperature is equal to or higher than the past estimated heat source temperature, and when the temperature difference obtained by subtracting the past estimated heat source temperature from the current saturation temperature is equal to or higher than the first P threshold, the first coefficient is set as a first P coefficient and calculated by the following formula 31: When the current saturation temperature is equal to or higher than the past estimated heat source temperature, and when a temperature difference obtained by subtracting the past estimated heat source temperature from the current saturation temperature is less than the first P threshold, the first coefficient is set to a second P coefficient smaller than the first P coefficient, and is calculated by the following formula 32: When the current saturation temperature is lower than the past estimated heat source temperature, and when the temperature difference obtained by subtracting the past estimated heat source temperature from the current saturation temperature is equal to or less than the 1N threshold, the first coefficient is set as a 1N coefficient and calculated by the following formula 33: When the current saturation temperature is lower than the past estimated heat source temperature, and when the temperature difference obtained by subtracting the past estimated heat source temperature from the current saturation temperature is greater than the 1N threshold, the first coefficient is set to a 2N coefficient smaller than the 1N coefficient, and is calculated by the following formula 34: The past estimated heat source temperature is a temperature calculated a first time ago using a calculation method similar to a calculation method of a current estimated heat source temperature, The current estimated detection part temperature in the step e is When the current estimated heat source temperature is higher than the past estimated detection unit temperature, and when the temperature difference obtained by subtracting the past estimated detection unit temperature from the current estimated heat source temperature is equal to or higher than the second P threshold, the second coefficient is set as a third P coefficient and calculated by the following formula 41: When the current estimated heat source temperature is higher than the past estimated detection unit temperature, and when the temperature difference obtained by subtracting the past estimated detection unit temperature from the current estimated heat source temperature is less than the second P threshold, the second coefficient is set to a fourth P coefficient smaller than the third P coefficient, and is calculated by the following formula 42: When the current estimated heat source temperature is equal to or lower than the past estimated detection unit temperature, and when the temperature difference obtained by subtracting the past estimated detection unit temperature from the current estimated heat source temperature is equal to or lower than the 2N threshold value, the second coefficient is set to a 3N coefficient and calculated by the following formula 43: When the current estimated heat source temperature is equal to or lower than the past estimated detection unit temperature, and when the temperature difference obtained by subtracting the past estimated detection unit temperature from the current estimated heat source temperature is greater than a second N threshold, the second coefficient is set to the fourth N coefficient which is smaller than the third N coefficient, and is calculated by the following formula 44: The past estimated detector temperature is a temperature calculated in the first time period before by a calculation method similar to that of the current estimated detector temperature. 8. The drive arrangement according to claim 4, wherein the drive arrangement is a drive mechanism for driving the vehicle. Current estimated heat source temperature = 1st P coefficient × (current saturation temperature - previous estimated heat source temperature) + previous estimated heat source temperature (Equation 31) Current estimated heat source temperature = 2nd P coefficient × (current saturation temperature - previous estimated heat source temperature) + previous estimated heat source temperature (Equation 32) Current estimated heat source temperature = 1st N coefficient × (current saturation temperature - previous estimated heat source temperature) + previous estimated heat source temperature (Equation 33) Current estimated heat source temperature = 2nd N coefficient × (current saturation temperature - previous estimated heat source temperature) + previous estimated heat source temperature (Equation 34) Current estimated detector temperature = 3rd P coefficient × (current estimated heat source temperature - previous estimated detector temperature) + previous estimated detector temperature (Equation 41) Current estimated detector temperature = 4th P coefficient × (current estimated heat source temperature - previous estimated detector temperature) + previous estimated detector temperature (Equation 42) Current estimated detector temperature = 3rd N coefficient × (current estimated heat source temperature - previous estimated detector temperature) + previous estimated detector temperature (Equation 43) Current estimated detector temperature = 4th N coefficient × (current estimated heat source temperature - previous estimated detector temperature) + previous estimated detector temperature (Equation 44)

[0015] [9] the step a, the step c, the step e, and the step i are repeated at each of the first time periods; The steps f, g, and h are repeated for a second time period that is longer than the first time period. The control device according to [8] above.

[0016]

[10] The first coefficient is a value greater than 0 and less than 1, and the second coefficient is a value greater than 0 and less than 1. The control device according to the above [8] or [9].

[0017]

[11] The control unit is When the value of the current flowing through the drive unit is less than a preset switching threshold current, or when the frequency of the current flowing through the drive unit is equal to or greater than a preset switching threshold frequency, the temperature obtained based on the detection result is regarded as the actual temperature detected by the temperature detection unit, rather than the estimated temperature for control. The drive device according to any one of the above items [8] to

[10] .

[0018]

[12] When the temperature obtained based on the detection result becomes equal to or higher than the abnormal threshold value, the control unit stops the drive unit and does not resume control of the drive unit until the operation of the control unit is reset. The drive device according to any one of the above [1] to

[11] ,

[0019]

[13] The drive unit is a motor; the power conversion unit includes a bridge circuit that generates a motor drive voltage for driving the motor from a DC voltage supplied from the current source, the control unit controls the power conversion unit to drive the motor by supplying the motor drive voltage to the motor; The temperature detection unit is a thermistor for detecting the temperature in the vicinity of the heat source. The drive device according to any one of the above [1] to

[12] ,

[0020]

[14] The heat source is: a transistor constituting a bridge circuit of the power conversion unit, The thermistor is Located adjacent to the transistor The drive device according to

[13] above,

[0021]

[15] The heat source is: a coil of the motor, The thermistor is Located adjacent to the coil The drive device according to

[13] above,

[0022]

[16] The drive device is mounted on an electric motorcycle, the load is a wheel of the electric motorcycle, The drive device according to any one of the above

[13] to

[15] , wherein the motor is connected to a wheel of the electric two-wheeler.

[0023]

[17] The torque input unit includes an accelerator position sensor that detects an amount of operation of an accelerator by a user of the electric motorcycle and transmits the amount of operation of the accelerator to the control unit as an electric signal; The drive device according to

[16] above, wherein the electrical signal is the command signal.

[0024]

[18] A control method for controlling a power conversion unit that converts power from a current source and supplies power to a drive unit, comprising: When a temperature obtained based on a detection result by a temperature detection unit disposed near a heat source generated by the power conversion unit or the drive unit is equal to or higher than a preset limit threshold and is in a limited state lower than a preset abnormality threshold higher than the limit threshold, the power conversion unit is controlled so that a limited torque smaller than a command torque corresponding to a command signal input from a torque input unit is output from the drive unit. A control method comprising:

[0025]

[19] The control unit is When the temperature obtained based on the detection result is equal to or higher than the abnormality threshold, the power conversion unit is controlled so that the torque output from the drive unit becomes zero. The control method according to

[18] above, Effect of the Invention

[0026] According to various aspects of the present invention, it is possible to provide a drive device and a control method that are capable of suppressing the temperature rise of the heat source of a component that generates heat when the drive unit is driven with a high current to increase the torque output from the drive unit. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic diagram illustrating a drive device according to an embodiment of the present invention. [Diagram 2] 1 is a schematic diagram illustrating an electric vehicle including a drive device according to an embodiment of the present invention; [Diagram 3] 3 is a diagram showing an example of a peripheral configuration of a power conversion unit 30c shown in FIG. 2. FIG. [Figure 4] FIG. 11 is a diagram showing the relationship between the temperature of a heat source and the control of a motor to perform a temperature protection function. [Diagram 5]FIG. 5 is a diagram showing an example of the characteristics of the target limit torque 57 at the limit threshold 51 shown in FIG. 4, and is a diagram showing the relationship between the target limit torque at the limit threshold and the frequency of the current flowing through the motor 3x. [Figure 6] This figure shows an example of the relationship between the motor current value 61, the actual thermistor temperature 62 detected by thermistor S, the actual temperature 63 of heat source Z, and the saturation temperature 64 of heat source Z when the motor is driven at a predetermined rotation speed. [Figure 7] 1 is a diagram showing an example of the relationship between the motor current and the saturation temperature of a heat source Z when the motor is driven at a predetermined rotation speed for a predetermined drive period. FIG. [Figure 8] This figure explains a method in which, when controlling the driving of a motor as a driving unit, the control unit selects the above-mentioned control estimated temperature or actual thermistor temperature as the temperature of the heat source that serves as the reference for executing the temperature protection function, in accordance with the relationship between the motor current value (phase current value) and the frequency of the current flowing through the motor. [Figure 9] FIG. 11 is a diagram showing the peripheral configuration of a power conversion unit 30c according to a third embodiment. [Figure 10] 11 is a diagram showing the relationship between the current application time and the temperature of the heat source when the motor is driven with a constant current and the temperature of the heat source increases. FIG. [Figure 11] 11 is a diagram showing the relationship between the current supply time and the temperature of the heat source when the temperature of the heat source decreases even when the motor is driven with a constant current. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that the form and details of the present invention can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0029] For example, a drive device will be described as a first embodiment, but this drive device can also be applied to an electric vehicle control device that drives a load of an electric vehicle, or this drive device can be applied to a device that controls a drive unit that drives a load other than the load of an electric vehicle.

[0030] (First embodiment) <Drive unit> Fig. 1 is a schematic diagram showing a driving device according to an embodiment of the present invention Fig. 4 is a diagram showing the relationship between the temperature of a heat source and the control of a motor to perform a temperature protection function.

[0031] The drive device shown in FIG. 1 includes a drive unit 3 that drives a load 8, a power conversion unit 30 that converts power from a current source 2 and supplies the power to the drive unit 3, and a temperature detection unit 11 that detects the temperature near a heat source generated by the power conversion unit 30 or the drive unit 3. The drive device also includes a control unit 10 that controls the power conversion unit 30 so that the drive unit 3 outputs a torque determined by a command signal input from an input unit (torque input unit) 5 that inputs torque and a temperature obtained based on the detection result of the temperature detection unit 11. Note that torque means a force in a direction that twists a rod-shaped object such as an axis. The current source 2 may be, for example, a battery, the drive unit 3 may be, for example, a motor, and the load 8 may be, for example, a wheel.

[0032] When the temperature obtained based on the detection result of the temperature detection unit 11 is equal to or higher than a preset limit threshold 51 and is lower than a preset abnormality threshold 52 higher than the limit threshold 51, as shown in FIG. 4, the control unit 10 may control the power conversion unit 30 to output from the drive unit 3 a limit torque 54 smaller than a command torque corresponding to a command signal input from the input unit 5. This makes it possible to prevent the temperature of the power conversion unit 30 or the drive unit 3, which generate heat, from rising too much when the drive unit 3 is driven with a high current to increase the torque output from the drive unit 3 in response to the command signal input from the input unit 5. As a result, it is possible to prevent parts from being damaged due to heat generated by the power conversion unit 30 or the drive unit 3.

[0033] In the case of an abnormal state 55 where the temperature obtained based on the detection result of the temperature detection unit 11 is equal to or higher than the abnormal threshold value 52 shown in Fig. 4, the control unit 10 may control the power conversion unit 30 so that the torque output from the drive unit 3 becomes zero. This stops the operation of the drive unit 3, and makes it possible to prevent the temperature of the heat-generating power conversion unit 30 or the drive unit 3 from rising too high.

[0034] When the temperature obtained based on the detection result of the temperature detection unit 11 is in a normal state 56 below a limit threshold value 51 shown in Fig. 4, the control unit 10 may control the power conversion unit 30 to output, from the drive unit 3, a command torque 58 corresponding to the command signal input from the input unit 5. In such a normal state 56, the temperature of the heat-generating power conversion unit 30 or the drive unit 3 does not rise too high.

[0035] 1 also has a storage unit 20 that stores a preset target limit torque table. This target limit torque table associates the frequency of the current flowing through the drive unit 3 with a target limit torque 57 when the temperature obtained based on the detection result of the temperature detection unit 11 is the limit threshold value shown in FIG. 4. By using this target limit torque 57, a minimum torque can be ensured.

[0036] In the case of the above-mentioned limited state 53, the control unit 10 may obtain the frequency of the current flowing through the drive unit 3, and set the limit torque 54 to be equal to or greater than the target limit torque 57 corresponding to the obtained frequency, with reference to the target limit torque table stored in the storage unit 20. This makes it possible to ensure a minimum torque while preventing the temperature of the heat-generating power conversion unit 30 or the drive unit 3 from rising too much when the drive unit 3 is driven with a high current to increase the torque output from the drive unit 3 in response to a command signal input from the input unit 5.

[0037] Second Embodiment <Electric vehicles>

[0038] FIG. 2 is a schematic diagram illustrating an electric vehicle including a drive device according to one embodiment of the present invention.

[0039] The electric vehicle in Fig. 2 is a vehicle that moves forward or backward by driving a motor 3x using power supplied from a battery 2a as a current source. Note that the motor 3x is an example of a drive unit.

[0040] The electric vehicle is, for example, an electric two-wheeled vehicle such as an electric motorcycle, and more specifically, an electric two-wheeled vehicle in which a motor 3x and a load 8 such as a wheel are mechanically connected directly without a clutch. Note that the electric vehicle according to one embodiment of the present invention is not limited to a two-wheeled vehicle, and may be, for example, a three- or four-wheeled electric vehicle.

[0041] The electric vehicle is equipped with a drive device shown in Fig. 1. As shown in Fig. 2, the drive device includes a load 8, a motor 3x as a drive unit, a power conversion unit 30c that converts power from a battery 2a as a current source and supplies the power to the motor 3x, a control device 1 having a temperature detection unit 11a and a control unit 10, and an accelerator position sensor (not shown) as a torque input unit. By installing the drive device on the electric vehicle in this manner, it is possible to prevent the temperature of the heat-generating power conversion unit 30c or the motor 3x from rising too high when the motor 3x is driven with a high current to increase the torque output from the motor 3x in response to a command signal input from the accelerator position sensor. As shown in FIG. 2, the electric vehicle further includes an angle sensor 4, an assist switch 6, a meter (display unit) 7, and a charger 9.

[0042] Each component of the electric vehicle shown in FIG. 2 will be described in detail below.

[0043] The control device 1 is a device that controls each component of an electric vehicle, and as described above, is mounted on, for example, an electric two-wheeler (electric vehicle). In this case, the load 8 is the wheel of the electric two-wheeler. The motor 3x is connected to the wheel of the electric two-wheeler. The control device 1 can control the power conversion unit 30 that converts power from the battery 2a and supplies the power to the motor 3x. By controlling the power conversion unit 30c, the motor 3x that drives the load 8 can be controlled.

[0044] The control device 1 may be configured as an ECU (Electronic Control Unit) that controls the entire electric vehicle.

[0045] As shown in Fig. 2, the control device 1 includes a control unit 10a, a storage unit 20a, and a temperature detection unit 11a. The temperature detection unit 11a is a thermistor S for detecting the temperature in the vicinity of a heat source Z of the power conversion unit 30c (see Fig. 3). However, as described later, the control device 1 may include a thermistor S for detecting the temperature in the vicinity of the heat source Z of the motor 3x.

[0046] The battery 2a supplies power to the motor 3x that rotates the load 8 of the electric vehicle. More specifically, the battery 2a supplies DC power to the power conversion unit 30c. The battery 2a is, for example, a lithium ion battery, but may be another type of battery. The battery 2a may also include a lead battery for supplying an operating voltage to the control unit 10a.

[0047] The battery 2a also includes a battery management unit (BMU). The battery management unit transmits battery information related to the voltage and state (charging rate, etc.) of the battery 2a to the control unit 10a. The number of batteries 2a is not limited to one, and may be multiple. That is, the electric vehicle may be provided with multiple batteries 2a connected in parallel or in series to each other.

[0048] The motor 3x is a three-phase motor driven by AC power supplied from the power conversion unit 30c. The motor 3x is mechanically connected to a wheel as a load 8, and rotates the wheel in a desired direction. In this embodiment, the motor 3x is mechanically connected directly to the wheel without a clutch (including a speed change mechanism). The type of the motor 3x is not particularly limited.

[0049] The angle sensor 4 is a sensor that detects the rotation angle of the rotor of the motor 3x. N-pole and S-pole magnets (sensor magnets) are attached alternately to the circumferential surface of the rotor (not shown).

[0050] The angle sensor 4 is configured, for example, by a Hall element, and is adapted to detect a change in a magnetic field accompanying the rotation of the motor 3x.

[0051] The accelerator position sensor detects the amount of accelerator operation by the user of the electric vehicle (electric two-wheeler) and transmits it to the control unit 10a as an electrical signal. The accelerator operation amount corresponds to the throttle opening of an engine vehicle.

[0052] By using the accelerator position sensor, when the user wishes to accelerate, the accelerator operation amount becomes large, and when the user wishes to decelerate, the accelerator operation amount becomes small.

[0053] The assist switch 6 is a switch that is operated by the user when requesting assistance of the electric vehicle. When operated by the user, the assist switch 6 transmits an assist request signal to the control unit 10a.

[0054] The meter (display unit) 7 is a display (e.g., a liquid crystal panel) provided on the electric vehicle, and displays various information. The meter 7 is provided, for example, on a handle (not shown) of the electric vehicle. The meter 7 displays information such as the traveling speed of the electric vehicle, the remaining charge of the battery 2a, the current time, the total traveling distance, and the remaining traveling distance. The remaining traveling distance indicates how far the electric vehicle can travel.

[0055] The charger 9 also has a power plug (not shown) and a converter circuit (not shown) that converts AC power supplied via the power plug into DC power. The battery 2a is charged with the DC power converted by the converter circuit. The charger 9 is communicatively connected to the control device 1 via, for example, a communication network (such as a CAN) in the electric vehicle.

[0056] Moreover, the control unit 10a is configured to receive and input information from various devices connected to the control device 1.

[0057] Specifically, the control unit 10a receives various signals output from the battery 2a, the angle sensor 4, the accelerator position sensor, the assist switch 6, and the charger 9. The control unit 10a outputs a signal to be displayed on the meter 7. The control unit 10a also controls the motor 3x via the power conversion unit 30c. The control unit 10a will be described in detail later.

[0058] The storage unit 20a also stores information used by the control unit 10a (such as various maps described below) and programs for the control unit 10a to operate. The storage unit 20a is, for example, a non-volatile semiconductor memory, but is not limited to this. The storage unit 20a may be incorporated as a part of the control unit 10a.

[0059] In particular, the storage unit 20a is adapted to store a saturation temperature information table (not shown). This saturation temperature information table is a table that associates a combination of a current value flowing through the motor 3x and a frequency of the current flowing through the motor 3x when the motor 3x is continuously driven at a predetermined rotation speed for a preset driving period with a saturation temperature, which is the maximum temperature at which the heat of the heat source Z generated when the motor 3x is driven is saturated. The above "combination of the value of the current flowing through the motor 3x and the frequency of the current flowing through the motor 3x" may be replaced with "combination of the value of the phase current of the motor 3x and the rotation speed of the motor 3x."

[0060] Furthermore, the storage unit 20a is configured to store a target limit torque table that associates the frequency of the current flowing through the motor 3x as a drive unit with the target limit torque when the heat source temperature is at the limit threshold, as described below. Note that the above "frequency of the current flowing through the motor 3x" may be replaced with "the rotation speed of the motor 3x."

[0061] The above-mentioned saturation temperature is the temperature of the heat source Z that becomes saturated when the control unit 10a controls the bridge circuit X of the power conversion unit 30c so that current is continuously applied to the motor 3x (current (phase current) flows continuously) at least during the driving period described above (see FIG. 6).

[0062] Moreover, the power conversion section 30c converts the DC power output from the battery 2a into AC power and supplies it to the motor 3x (see FIG. 3).

[0063] The power conversion unit 30c, which is an inverter device, includes a three-phase bridge circuit X including first to third half bridges that generates a motor drive voltage for driving the motor 3x from the DC voltage supplied from the battery 2a. By including this bridge circuit X, the phase and wave height of the sine wave required to drive the motor can be controlled, and the motor can be used efficiently to minimize heat generation.

[0064] As shown in FIG. 3, each of the first to third half bridges includes high-side transistors (semiconductor switches Q1, Q3, Q5) and low-side transistors (semiconductor switches Q2, Q4, Q6) connected in series.

[0065] The control terminals of the semiconductor switches Q1 to Q6 are electrically connected to the control unit 10a. A smoothing capacitor C is provided between the power supply terminal 30a and the power supply terminal 30b. The semiconductor switches Q1 to Q6 are, for example, MOSFETs or IGBTs.

[0066] As shown in FIG. 3, the semiconductor switch Q1 is connected between a power supply terminal 30a to which the positive electrode of the battery 2a is connected and an input terminal 3a of the motor 3x.

[0067] Similarly, the semiconductor switch Q3 is connected between the power supply terminal 30a and the input terminal 3b of the motor 3x.

[0068] The semiconductor switch Q5 is connected between the power supply terminal 30a and the input terminal 3c of the motor 3x.

[0069] The semiconductor switch Q2 is connected between an input terminal 3a of the motor 3x and a power supply terminal 30b to which the negative electrode of the battery 2a is connected.

[0070] Similarly, the semiconductor switch Q4 is connected between the input terminal 3b of the motor 3x and the power supply terminal 30b.

[0071] The semiconductor switch Q6 is connected between the input terminal 3c of the motor 3x and the power supply terminal 30b.

[0072] The input terminal 3a is a U-phase input terminal of the motor 3x, the input terminal 3b is a V-phase input terminal of the motor 3x, and the input terminal 3c is a W-phase input terminal of the motor 3x.

[0073] In addition, the control unit 10a controls the power conversion unit 30c to output a command torque from the motor 3x in response to a command signal input from the outside, and supplies a motor drive voltage to the motor 3x, thereby driving the motor 3x.

[0074] As described above, the accelerator position sensor detects the amount of operation of the accelerator by the user of the electric vehicle (electric two-wheeler) and transmits it as an electric signal to the control unit 10. In this case, the electric signal output by the accelerator position sensor corresponds to the command signal.

[0075] The control unit 10a controls the semiconductor switches Q1 to Q6 of the power conversion unit 30c to turn on and off in accordance with the motor stage, thereby converting the DC power supplied from the battery 2a into AC power.

[0076] The thermistor S is disposed near a heat source Z to detect the temperature of the heat source Z (see FIG. 3). As shown in FIG. 3, the heat source Z is made up of transistors Q1 to Q6 that form a bridge circuit X of the power conversion unit 30c.

[0077] In this embodiment, the thermistor S is disposed adjacent to the transistors Q1 to Q6. By using the thermistor S, the board design is easy and the temperature can be read from the resistance change due to the temperature, so that the conversion control can be simply configured.

[0078] In particular, as shown in Fig. 3, the thermistor S includes three thermistors S1, S2, and S3. The thermistor S1 is disposed near the high-side transistor Q1 of the first half-bridge. The thermistor S2 is disposed near the high-side transistor Q3 of the second half-bridge. The thermistor S3 is disposed near the high-side transistor Q5 of the third half-bridge.

[0079] In this manner, the thermistors S (S1, S2, S3) are disposed near the high-side transistors Q1, Q3, Q5 of the first to third half bridges, which are considered to generate particularly large amounts of heat.

[0080] <Temperature protection function execution> Fig. 4 is a diagram showing the relationship between the temperature of the heat source and the control of the motor in order to execute the temperature protection function. Fig. 5 is a diagram showing an example of the characteristics of the target limit torque 57 at the limit threshold 51 shown in Fig. 4.

[0081] As shown in Fig. 5, the target limit torque 57 at the limit threshold and the frequency of the current flowing through the motor 3x have a quadratic function relationship. That is, when the heat source temperature is the limit threshold 51 shown in Fig. 4, the target limit torque 57 is set to increase as the frequency of the current flowing through the motor 3x increases, and to decrease as the frequency of the current flowing through the motor 3x decreases (see Fig. 5). In addition, the "frequency of the current flowing through the motor 3x" above and below may be replaced with the "number of rotations of the motor 3x." In addition, the heat source temperature above and below is a temperature obtained based on the detection result of the thermistor S serving as a temperature detection unit.

[0082] The storage unit 20a also stores a target limit torque table that associates the frequency of the current flowing through the motor 3x with the target limit torque 57 when the heat source temperature is equal to the limit threshold value 51. Therefore, the control unit 10a can obtain the target limit torque 57 associated with the frequency of the current flowing through the motor 3x by referring to the target limit torque table stored in the storage unit 20a.

[0083] Moreover, the target limit torque table is preferably set so that the target limit torque 57 increases as the frequency of the current flowing through the motor 3x as the drive unit increases, and the target limit torque 57 decreases as the frequency of the current flowing through the motor 3x decreases. This makes it possible to ensure a minimum torque at the limit threshold 51. In addition, this "the target limit torque 57 is set to increase as the frequency of the current flowing through the motor 3x increases, and the target limit torque 57 is set to decrease as the frequency of the current flowing through the motor 3x decreases" may be replaced with "the target limit torque is set to increase as the rotation speed of the motor 3x increases, and the target limit torque is set to decrease as the rotation speed of the motor 3x decreases."

[0084] Here, in order to execute the temperature protection function, as shown in FIG. 4, in a restricted state 53 in which the heat source temperature obtained based on the detection result of the thermistor S is equal to or higher than a preset restriction threshold 51 and is lower than a preset abnormality threshold 52 higher than the restriction threshold 51, the control unit 10a controls the power conversion unit 30c to drive the motor 3x so as to output a restricted torque 54 that is smaller than the command torque corresponding to the command signal described above.

[0085] The heat source temperature described above and below may be an estimated temperature for control or an actual thermistor temperature (actual temperature), which will be described later.

[0086] To explain the limit torque 54 in detail, first, the control unit 10a obtains the frequency of the current flowing through the motor 3x.

[0087] Also, the above "acquire the frequency of the current flowing through the motor 3x" may be replaced with "acquire the rotation speed of the motor 3x." Note that the control unit 10a can acquire the rotation speed of the motor 3x based on a signal output by a hall element (not shown) provided in the motor 3x in response to the rotation of the motor 3x, for example.

[0088] Next, the control unit 10a refers to a target limit torque table stored in the storage unit 20a and sets the limit torque so that it is equal to or greater than the target limit torque 57 corresponding to the acquired frequency. Note that the "acquired frequency" may be replaced with the "acquired rotation speed."

[0089] This prevents the temperature of the transistors Q1 to Q6, which are the heat source Z, from rising and being damaged, and allows the electric vehicle to continue running while lowering the torque of the motor 3x. The reason for setting the magnitude of the target limit torque 57 or more is that the purpose is not to lower the temperature range of the limited state 53 shown in FIG. 4 to the temperature of the normal state 56, but to prevent the temperature range of the abnormal state 55 from being exceeded beyond the limited state 53. If the target limit torque is set to less than the magnitude of the target limit torque 57, the purpose is to lower the temperature from the limited state 53 to the normal state 56, but in that case, the user will only be able to output a torque significantly lower than the command torque, which will not satisfy the user. The limit torque 54 is set so that the heat source temperature does not exceed the abnormality threshold value 52 .

[0090] As explained above, in the restricted state 53, when the torque of the motor 3x is increased by user operation, causing a high current to flow when the motor 3x is at a low angular velocity, and the temperature of the heat source Z generated when the motor 3x is driven rises to or above the restriction threshold 51 that activates the temperature protection function, the control unit 10a operates to limit the output torque of the motor regardless of the user operation, thereby suppressing the rise in temperature.

[0091] On the other hand, when the heat source temperature is equal to or higher than the abnormality threshold 52, that is, an abnormal state 55, the control unit 10a controls the power conversion unit 30c to stop the motor 3x so that the torque output from the motor 3x becomes zero, regardless of the command signal (see FIG. 4).

[0092] For example, the control unit 10a may determine that an abnormal state 55 in which the heat source temperature is equal to or higher than the abnormality threshold value 52 is a state in which an abnormality has occurred in the system of the control unit 10a. This allows the traveling of the electric vehicle to be appropriately stopped when an abnormality occurs in the transistors Q1 to Q6, for example.

[0093] Furthermore, when the heat source temperature exceeds the abnormality threshold 52, the control unit 10a may, for example, stop the motor 3x and then not resume control of the motor 3x until the operation of the control unit 10a is reset. In this way, when heat that exceeds the abnormality threshold, which cannot occur within the designed normal range, is generated, it is determined that a system abnormality has occurred, and the system can be safely stopped before it is damaged.

[0094] In the abnormal state 55, when an abnormality occurs in the control unit 10a, the power conversion unit 30c, or the like, and the heat source Z becomes extremely hot, the operation of the control unit 10a makes it possible to appropriately stop the motor 3x.

[0095] In addition, in a normal state 56 in which the heat source temperature is below the limit threshold value 51, the control unit 10a controls the power conversion unit 30c to drive the motor 3x so as to output a command torque 58 in accordance with the command signal (see FIG. 4).

[0096] In this normal state 56, the control unit 10a operates to cause the motor to output a command torque 58 in response to a command signal based on a user's operation.

[0097] <An example of operation at limited torque in a limited state> Here, an example of an operation in which the control unit 10a calculates the limit torque 54 in the above-mentioned limited state and drives the motor 3x with this limit torque 54 will be described.

[0098] First, in the restricted state shown in FIG. 4, the control unit 10a calculates a temperature difference value (e.g., 0.4), which is a parameter of the temperature difference between the heat source temperature (e.g., 150°C) and the restriction threshold 51 (e.g., 130°C), by multiplying the value obtained by subtracting the restriction threshold 51 (e.g., 130°C) from the heat source temperature (e.g., 150°C) by a positive adjustment coefficient (e.g., 0.02), as shown in the following (Equation A).

[0099] Moreover, the above-mentioned adjustment coefficient is set, for example, so that the heat source temperature falls within the range from the limit threshold 51 to the abnormality threshold 52 in a state in which the torque output by the motor 3x is the limit torque 54. Temperature difference value = Positive adjustment coefficient × (Heat source temperature - Limit threshold) (Formula A)

[0100] Next, the control unit 10a acquires the frequency of the current flowing through the motor 3x serving as a drive unit or the number of rotations of the motor 3x (for example, 1000 rpm). Next, a target limit torque 57 (for example, 20 N·m) corresponding to the above-mentioned acquired frequency is calculated by referring to a target limit torque table stored in the storage unit 20a.

[0101] Next, the control unit 10a calculates a negative cut torque (e.g., −2.4 N·m) to be subtracted from the command torque 58 by multiplying the value obtained by subtracting the current torque (e.g., 26 N·m) currently being output by the motor 3x from the target limit torque 57 by the temperature difference value (e.g., 0.4) as shown in the following (Equation B). Cut torque = temperature difference value × (target limit torque - current torque) (Formula B)

[0102] Next, the control unit 10a calculates the limit torque 54 (e.g., 23.6 N·m) by adding a negative cut torque (e.g., −2.4 N·m) to the command torque 58 (e.g., 26 N·m) (i.e., subtracting the absolute value of the cut torque from the command torque) as shown in the following (Equation C). Limit torque = command torque + cut torque (equation C)

[0103] Then, the control unit 10a controls the power conversion unit 30c to output a limit torque 54 (e.g., 23.6 N·m) to drive the motor 3x. This makes it possible to keep the heat source temperature within a range from a limit threshold 51 (e.g., 130°C) to an abnormality threshold 52 (e.g., 160°C).

[0104] As a result, when the user operates the throttle to increase the motor output torque, causing a high current to flow while the motor is at a low angular velocity and causing the temperature of the heat source to rise above the threshold for executing the temperature protection function, the motor output torque is limited regardless of the user's throttle operation, thereby suppressing the rise in temperature of the heat source and allowing the electric vehicle to continue running.

[0105] <How to estimate the heat source temperature used when executing the temperature protection function> An example of a method for estimating the heat source temperature used when executing the temperature protection function by the control device 1 described above will be described. Here, we consider a physical model based on the on-resistance of the transistor, which is the heat source Z, the temperature rise due to the current of the motor 3x as the driving part, the heat capacity of the unit, and thermal conduction with the ambient temperature of the unit.The temperature of the transistor is then estimated from the saturation temperature when time has passed until the heat of the heat source is saturated.This method uses the actual temperature to prevent any discrepancy between this estimated temperature and the actual temperature due to calculation errors (see Figure 6). In addition, the "current of the motor 3x" above and below may be replaced with the "phase current of the motor 3x".

[0106] First, to implement the temperature protection function, the control unit 10a acquires the current value flowing through the motor 3x (detects the phase current of the motor 3x and acquires the phase current value (e.g., 100 A)), and also acquires the frequency of the current flowing through the motor 3x (or the rotation speed of the motor 3x (e.g., 1000 rpm)).

[0107] In addition, when detecting the current (phase current), the peak current of each current (each phase current) may be obtained for each of six stages defined by the on / off combinations of each transistor Q1 to Q6 of the motor 3x during 120° and 180° energization, and the switching noise may be removed and averaged to obtain the current value (phase current value).

[0108] As described above, the memory unit 20a stores a saturation temperature information table that associates a combination of the current value (phase current value) flowing through the motor 3x and the frequency of the current flowing through the motor 3x (or the rotation speed of the motor 3x) when the motor 3x is driven continuously at a predetermined rotation speed for a preset drive period, with the saturation temperature, which is the maximum temperature at which the heat of the heat source Z generated when the motor 3x is driven, is saturated (see Figure 7).

[0109] (Step a) The control unit 10a refers to the saturation temperature information table stored in the memory unit 20a and calculates the current saturation temperature (e.g., 90°C) of the heat source Z that corresponds to (is associated with) the combination of the acquired current value (phase current value; e.g., 100 A) and the acquired frequency (or rotation speed (e.g., 1000 rpm)).

[0110] In this way, the current saturation temperature of the heat source Z is calculated based on each measurement data of the current current value (phase current value) and frequency (or rotation speed) with reference to a preset saturation temperature information table.

[0111] Next, the control unit 10a calculates the current estimated heat source temperature as the provisionally estimated temperature of the heat source Z by using a first coefficient (time constant) based on a first-order lag relationship 65 of the time change of the temperature of the heat source Z with respect to the current saturation temperature, as shown in the following (Equation 1). In other words, as shown in Fig. 6, the temperature of the heat source is estimated by using a time constant (first coefficient) based on a first-order lag relationship 65 with respect to the current saturation temperature. Note that this first coefficient is, for example, a value greater than 0 and less than 1. This first coefficient makes it possible to correct the first-order lag for the current saturation temperature.

[0112] The method of calculating the current estimated heat source temperature will be described in detail below. First, the first coefficient will be described in detail below. Fig. 10 is a diagram showing the relationship between the power supply time and the temperature of the heat source when the motor is driven with a constant current and the temperature of the heat source rises. Fig. 11 is a diagram showing the relationship between the power supply time and the temperature of the heat source when the motor is driven with a constant current and the temperature of the heat source falls.

[0113] (Step b) The current saturation temperature is compared with the previously estimated heat source temperature (e.g. 100°C) calculated a first time ago (e.g. 10 ms) (one time ago). At this time, if the current saturation temperature is equal to or higher than the previously estimated heat source temperature (formula a below), it is determined that the heat source temperature will rise. At this time, the first coefficient is positive (P). (Current saturation temperature - Previous estimated heat source temperature) ≧ 0 (Equation a) The past estimated heat source temperature is a temperature calculated before the first time period by a method similar to the method for calculating the current estimated heat source temperature. If the past estimated heat source temperature has not been calculated, the actual thermistor temperature detected by thermistor S may be used.

[0114] When the first coefficient is positive (P) and the temperature difference between the current saturation temperature and the past estimated heat source temperature is equal to or greater than the P slope threshold (first P threshold; for example, 20°C) (formula b) below, it is determined that the temperature rise of the heat source is rapid (i) below. The P slope threshold is also called. (Current saturation temperature - Previous estimated heat source temperature) ≧ P slope threshold (equation b) (i) In the case where the temperature of the heat source rises rapidly toward the current saturation temperature (reference numeral 81 in FIG. 10), the P coefficient (steep) is used as the first coefficient. This P coefficient (steep) is, for example, 0.05. This P coefficient (steep) is also called the first P coefficient.

[0115] In addition, when the first coefficient is positive (P) and the temperature difference between the current saturation temperature and the previously estimated heat source temperature is less than the P slope threshold (first P threshold; for example, 20°C) (equation c) below, it is determined that the temperature rise of the heat source is gradual, that is, (ii) below. (Current saturation temperature - Previous estimated heat source temperature) < P slope threshold (equation c) (ii) In the case where the temperature of the heat source rises slowly toward the current saturation temperature (reference numeral 82 in FIG. 10), the P coefficient (slow) is used as the first coefficient. This P coefficient (slow) is, for example, 0.03. This P coefficient (slow) is smaller than the P coefficient (fast) and is also called the second P coefficient.

[0116] In addition, if the current saturation temperature is lower than the past estimated heat source temperature (equation d), it is determined that the heat source temperature is decreasing. In this case, the first coefficient is negative (N). (Current saturation temperature - Previous estimated heat source temperature) < 0 (Equation d) When the first coefficient is negative (N) and the temperature difference between the current saturation temperature and the previously estimated heat source temperature is below the N slope threshold (first N threshold; for example, -30°C) (equation e) below, it is determined that the temperature drop of the heat source is rapid, as in (iii) below. (Current saturation temperature - Previous estimated heat source temperature) ≦ N slope threshold (Equation e) (iii) In the case where the temperature of the heat source drops rapidly toward the current saturation temperature (reference numeral 83 in FIG. 11), the N coefficient (steep) is used as the first coefficient. This N coefficient (steep) is, for example, 0.06. This N coefficient (steep) is also called the first N coefficient.

[0117] In addition, when the first coefficient is negative (N) and the temperature difference between the current saturation temperature and the previously estimated heat source temperature is greater than the N slope threshold (first N threshold; for example, -30°C) (equation f) below, it is determined that the temperature drop of the heat source is gradual, as in (iv) below. (Current saturation temperature - Previous estimated heat source temperature) > N slope threshold (equation f) (iv) In the case where the temperature of the heat source slowly drops toward the current saturation temperature (reference numeral 84 in FIG. 11), the N coefficient (slow) is used as the first coefficient. This N coefficient (slow) is, for example, 0.04. Note that the N coefficient (slow) is smaller than the N coefficient (fast), and is also called the second N coefficient.

[0118] Based on the above judgment, one of the P coefficients (steep) to N coefficients (gentle) listed above in (i) to (iv) will be used as the first coefficient. Since the first coefficient is a time constant, the coefficient becomes complex whether the temperature is rising or falling. However, by approximating the time constant to the above four cases, the calculation load can be reduced and the accuracy of the temperature estimation of the heat source can be improved.

[0119] (Step c) Next, as shown in the following (Equation 1), the first coefficient determined as explained above (i.e., P coefficient (rapid), P coefficient (gentle), N coefficient (rapid), N coefficient (gentle)) is multiplied by the difference between the current saturation temperature (e.g., 90°C) calculated by the method described above and the previously estimated heat source temperature (e.g., 100°C) and added to the previously estimated heat source temperature to calculate the current estimated heat source temperature (e.g., 99.6°C) as the provisionally estimated heat source temperature. Current estimated heat source temperature = First coefficient (either P coefficient (rapid), P coefficient (slow), N coefficient (rapid), or N coefficient (slow)) × (current saturation temperature - previous estimated heat source temperature) + previous estimated heat source temperature (Formula 1)

[0120] In this way, the temperature of the transistor, which is the heat source Z, is tentatively estimated from the current saturation temperature using the first coefficient obtained by digitizing the time constant.

[0121] Next, the control unit 10a calculates a current estimated thermistor temperature, which is a provisionally estimated temperature of the thermistor, based on a first-order lag relationship 66 of the time change of heat conduction from the heat source Z to thermistor S as shown in the following (Equation 2) by using a second coefficient (time constant) different from the above-mentioned first coefficient. In other words, as shown in Fig. 6, the actual thermistor temperature is estimated by using a time constant (second coefficient) based on a first-order lag relationship 66 of the time change of heat conduction from the heat source Z to thermistor S. The current estimated thermistor temperature is also referred to as the current estimated detection portion temperature. Moreover, this second coefficient is, for example, a value greater than 0 and less than 1. This second coefficient makes it possible to correct the first-order lag of the time change in heat conduction from the heat source Z to the thermistor S.

[0122] A method for calculating the above-mentioned current estimated thermistor temperature (current estimated detection portion temperature) will be described in detail below.

[0123] First, the second coefficient will be described in detail below. (Step d) The current estimated heat source temperature calculated using (Equation 1) above is compared with the previous estimated thermistor temperature calculated a first time ago (e.g. 10 ms) (one time ago). At this time, if the current estimated heat source temperature is higher than the previous estimated thermistor temperature (Equation g) below, it is determined that the thermistor temperature is rising. In this case, the second coefficient is positive (P). (Current estimated heat source temperature - Previous estimated thermistor temperature) ≧ 0 (equation g) The past estimated thermistor temperature is a temperature calculated before the first time period using a method similar to the method for calculating the current estimated thermistor temperature. If the past estimated thermistor temperature has not been calculated, the actual thermistor temperature detected by thermistor S may be used.

[0124] When the second coefficient is positive (P) and the temperature difference between the current estimated heat source temperature and the previously estimated thermistor temperature is greater than or equal to the P slope threshold (second P threshold; for example, 20°C) (equation h) below, it is determined that the thermistor temperature rise is rapid, as in (i) below. (Current estimated heat source temperature - Previous estimated thermistor temperature) ≧ P slope threshold (equation h) (i) In the case where the temperature of the thermistor rises suddenly, the P coefficient (steep) is used as the second coefficient. This P coefficient (steep) is, for example, 0.03. This P coefficient (steep) is also called the third P coefficient.

[0125] In addition, when the second coefficient is positive (P) and the temperature difference between the current estimated heat source temperature and the previously estimated thermistor temperature is less than the P slope threshold (second P threshold; for example, 20°C) (equation i) below, it is determined that the temperature rise of the thermistor is gradual, as in (ii) below. (Current estimated heat source temperature - Previous estimated thermistor temperature) < P slope threshold (equation i) (ii) In the case where the temperature of the thermistor rises slowly, the P coefficient (slow) is used as the second coefficient. This P coefficient (slow) is, for example, 0.02. This P coefficient (slow) is smaller than the P coefficient (fast) and is also called the fourth P coefficient.

[0126] In addition, in the case where the current estimated heat source temperature is lower than the previous estimated thermistor temperature (expression j), it is determined that the thermistor temperature is decreasing. In this case, the second coefficient is negative (N). (Current estimated heat source temperature - Previous estimated thermistor temperature) < 0 (equation j) When the second coefficient is negative (N) and the temperature difference between the current estimated heat source temperature and the previously estimated thermistor temperature is below the N slope threshold (second N threshold; for example, -10°C) (equation k) below, it is determined that the thermistor temperature drop is rapid, as in (iii) below. (Current estimated heat source temperature - Previous estimated thermistor temperature) ≦ N slope threshold (equation k) (iii) In the case where the temperature of the thermistor drops suddenly, the N coefficient (steep) is used as the second coefficient. This N coefficient (steep) is, for example, 0.02. The N coefficient (steep) is also called the third N coefficient.

[0127] In addition, when the second coefficient is negative (N) and the temperature difference between the current estimated heat source temperature and the previously estimated thermistor temperature is greater than the N slope threshold (second N threshold; for example, −10°C) (equation m) below, it is determined that the thermistor temperature is decreasing slowly, as in (iv) below. (Current estimated heat source temperature - Previous estimated thermistor temperature) > N slope threshold (equation m) (iv) In the case where the temperature of the thermistor drops slowly, the N coefficient (slow) is used as the second coefficient. This N coefficient (slow) is, for example, 0.01. The N coefficient (slow) is smaller than the 3rd N coefficient and is also called the 4th N coefficient.

[0128] Based on the above judgment, one of the P coefficients (steep) to N coefficients (gentle) listed above in (i) to (iv) will be used as the second coefficient. Since the second coefficient is a time constant, the coefficient becomes complex whether the temperature is rising or falling. However, by approximating the time constant to the above four cases, the calculation load can be reduced and the accuracy of the temperature estimation of the heat source can be improved.

[0129] (Step e) Next, as shown in the following (Equation 2), the second coefficient determined as explained above (i.e., P coefficient (fast), P coefficient (slow), N coefficient (fast), N coefficient (slow)) is multiplied by the difference between the current estimated heat source temperature (e.g., 46.65°C) calculated in the above (Equation 1) and the previous estimated thermistor temperature (e.g., 30°C) and added to the previous estimated thermistor temperature to calculate the current estimated thermistor temperature (e.g., 30.5), which is a provisionally estimated thermistor temperature. Current estimated thermistor temperature = 2nd coefficient (either P coefficient (fast), P coefficient (slow), N coefficient (fast), or N coefficient (slow)) × (current estimated heat source temperature - previous estimated thermistor temperature) + previous estimated thermistor temperature... (Equation 2)

[0130] In this manner, the temperature of thermistor S is estimated using the second coefficient obtained by digitizing the time constant.

[0131] (Step f) Next, the control unit 10a obtains the actual thermistor temperature detected by the thermistor S (for example, 30.9° C.).

[0132] (Step g) Next, the control unit 10a calculates a temperature difference (e.g., 0.4°C) by subtracting the actual thermistor temperature (e.g., 30.9°C) detected by thermistor S from the current estimated thermistor temperature (e.g., 30.5°C) in the above (Equation 2) as shown in the following (Equation 3). Current estimated thermistor temperature - Actual thermistor temperature = Temperature difference (Equation 3) The actual thermistor temperature is also called the actual temperature.

[0133] (Step h) Next, the control unit 10a multiplies the temperature difference calculated in the above (Equation 3) by a preset temperature correction coefficient (e.g., 0.9) as shown in the following (Equation 4), thereby calculating a temperature correction value (e.g., 0.36°C) for correcting the current estimated heat source temperature (e.g., 46.65°C) in the above (Equation 1). Temperature difference × temperature correction coefficient = temperature correction value (Equation 4) The temperature correction coefficient is a ratio at which a temperature difference due to the type of temperature detection unit (eg, a thermistor) and individual variations is reflected in the control estimated temperature.

[0134] (Step i) Next, the control unit 10a calculates a control estimated temperature (e.g., 47.01°C) by adding the temperature correction value of the above (Equation 4) to the current estimated heat source temperature of the above (Equation 1), as shown in the following (Equation 5). Current estimated heat source temperature + temperature correction value = estimated temperature for control (Equation 5) The above steps (a) to (e) and (i) are repeated every first time (e.g., every 10 ms), and the above steps (f) to (h) are repeated every second time (e.g., every 100 ms). As a result, by calculating the temperature correction value for correcting the temperature error every second time, which is longer than the first time, from (f) to (h), it is possible to reduce the load on the control unit while maintaining the accuracy of the estimated temperature for control. Note that, since the temperature correction value for (h) can only be obtained every 100 ms, the same temperature correction value is used 10 times in (i) which is performed every 10 ms. Furthermore, the control estimated temperature obtained every first time (e.g., every 10 ms) and the current estimated heat source temperature in the calculation process are stored in the storage unit, and the temperature correction value obtained every second time (e.g., every 100 ms) and the current estimated thermistor temperature in the calculation process are stored in the storage unit. The current saturation temperature obtained every first time may also be stored in the storage unit, and the actual temperature obtained every second time may also be stored in the storage unit.

[0135] It is advisable to return the previous estimated thermistor temperature to the actual thermistor temperature at regular intervals. The reason for this is that the error in the control estimated temperature accumulates and, as a countermeasure, the control estimated temperature is corrected and returned before the difference with the actual temperature due to the error becomes too large. For example, the current estimated heat source temperature and the current estimated thermistor temperature are calculated every 10 msec, and the current estimated heat source temperature is corrected using the actual thermistor temperature every 100 msec.

[0136] When the temperature protection function is executed, the temperature of the heat source (driver circuit transistor) Z can be estimated based on the temperature detected by the thermistor, the motor current, and the frequency of that current, taking into account the effects of thermal conduction and ambient temperature. This allows the calculated estimated control temperature to be the heat source temperature when the above-mentioned temperature protection function is executed.

[0137] In addition, when executing the temperature protection function, by using the above-mentioned control estimated temperature, which is estimated taking into account the first-order lag characteristics with the saturation temperature of the heat source Z as the reference, it is possible to more reliably prevent failure of the transistor, which is the heat source Z.

[0138] <How to select the heat source temperature that will be the reference for executing the temperature protection function> 8 is a diagram for explaining a method in which, when controlling the driving of a motor serving as a driving unit, the control unit selects the above-mentioned estimated control temperature or the actual thermistor temperature (actual temperature) as the temperature of the heat source serving as the reference for executing the temperature protection function, in accordance with the relationship between the motor current value and the frequency of the current flowing through the motor serving as a driving unit. In other words, the control unit 10a may switch the temperature of the heat source serving as the reference for executing the temperature protection function between the above-mentioned estimated control temperature and the temperature (actual temperature) detected by the thermistor S. In FIG. 8, the temperature of the heat source that is the reference for executing the temperature protection function is selected from the above-mentioned estimated control temperature or actual thermistor temperature (actual temperature) in accordance with the relationship between the motor current value and the frequency of the current flowing through the motor. However, it is also possible to select the temperature of the heat source that is the reference for executing the temperature protection function from the above-mentioned estimated control temperature or actual thermistor temperature (actual temperature) in accordance with the relationship between the motor phase current value and the motor rotation speed.

[0139] In a first case where the current value of the current of the motor 3x is equal to or greater than a preset switching threshold current 45 and the frequency of the current flowing through the motor 3x is less than a preset switching threshold frequency 46, the control unit 10a controls the power supplied from the power conversion unit 30c to the motor 3x based on a control estimated temperature 47. This controls the driving of the motor 3x. In addition, the above "first case in which the current value of the current of the motor 3x is equal to or greater than the predetermined switching threshold current 45 and the frequency of the current flowing through the motor 3x is less than the predetermined switching threshold frequency 46" may be replaced with "first case in which the phase current value flowing through the motor 3x is equal to or greater than the predetermined switching threshold current and the rotation speed of the motor 3x is less than the predetermined switching threshold rotation speed." Furthermore, the "current value of the current of the motor 3x" above and below may be replaced with the "phase current value of the phase current of the motor 3x."

[0140] In the first case, since the motor 3x is driven with a high current and a low frequency, the temperature detected by the thermistor S cannot adequately track the actual temperature of the heat source Z. In such a case, however, the power conversion unit 30c controls the driving of the motor 3x while executing the temperature protection function based on the above-mentioned estimated control temperature calculated by estimating the temperature of the heat source more accurately. This makes it possible to prevent damage to the power conversion unit 30c having the heat source.

[0141] On the other hand, in a second case where the current value of the current through the motor 3x is less than the switching threshold current 45 or the frequency of the current flowing through the motor 3x is equal to or greater than the switching threshold frequency 46, the control unit 10a controls the power supplied from the power conversion unit 30c to the motor 3x based on the actual thermistor temperature (actual temperature) 50 detected by the thermistor S. This controls the driving of the motor 3x.

[0142] In addition, the above "second case in which the current value of the current flowing through motor 3x is less than the switching threshold current 45, or the frequency of the current flowing through motor 3x is greater than or equal to the switching threshold frequency 46" may be replaced with "second case in which the phase current value flowing through motor 3x is less than the switching threshold current, or the rotation speed of motor 3x is greater than or equal to the switching threshold rotation speed."

[0143] In the second case described above, since the motor 3 is driven with a low current or a high frequency, the temperature detected by the thermistor S can adequately track the actual temperature of the heat source Z. In such a case, the power conversion unit 30c controls the driving of the motor 3x while executing the temperature protection function based on the actual thermistor temperature detected by the thermistor S. This makes it possible to prevent damage to the power conversion unit 30c having the heat source.

[0144] Here, as shown in FIG. 8, the above-mentioned control estimated temperature and the actual thermistor temperature detected by the thermistor S may be switched so as to have a hysteresis characteristic.

[0145] In detail, when the frequency of the current flowing through the motor 3x is less than the switching threshold frequency 46 and the current value of the current through the motor 3x decreases from greater than or equal to the switching threshold current 45 to a preset hysteresis threshold current 49 that is less than the switching threshold current 45, i.e., when transitioning from the first case to the second case as shown by arrow 41, the control unit 10a continues to control the driving of the motor 3 by the power conversion unit 30 based on the control estimated temperature (see Figure 8).

[0146] In addition, the above statement "the frequency of the current flowing through motor 3x is less than the switching threshold frequency 46, and the value of the current flowing through motor 3x decreases from greater than or equal to the switching threshold current 45 to a preset hysteresis threshold current 49 that is smaller than the switching threshold current 45" may be replaced with "the rotation speed of motor 3x is less than the switching threshold rotation speed, and the phase current value of the phase current of motor 3x decreases from greater than or equal to the switching threshold current to a preset hysteresis threshold current that is smaller than the switching threshold current."

[0147] When transitioning from the first case to the second case as indicated by arrow 41, it takes time for the temperature to converge, so the detected temperature of the thermistor S may not be able to adequately track the temperature of the heat source Z. In this case, the power conversion unit 30c controls the driving of the motor 3x while executing the temperature protection function based on the above-mentioned estimated control temperature. This makes it possible to prevent damage to the power conversion unit 30c having a heat source.

[0148] On the other hand, when the frequency of the current flowing through the motor 3x is less than the switching threshold frequency 46 and the current value of the current through the motor 3x rises from less than the hysteresis threshold current 49 to the switching threshold current 45, i.e., when transitioning from the above-mentioned second case to the first case as shown by arrow 42, the control unit 10a continues to control the driving of the motor 3 by the power conversion unit 30 based on the actual thermistor temperature (actual temperature) 50 (see Figure 8).

[0149] In addition, the above statement "the frequency of the current flowing through motor 3x is less than the switching threshold frequency 46, and the current value of the current of motor 3x rises from less than the hysteresis threshold current 49 to the switching threshold current 45" may be replaced with "the rotation speed of motor 3x is less than the switching threshold rotation speed, and the phase current value of the phase current of motor 3x rises from less than the hysteresis threshold current to the switching threshold current."

[0150] When the transition occurs from the second case to the first case as indicated by the arrow 42, the temperature rise is rapid, so the temperature detected by the thermistor S can adequately follow the temperature of the heat source Z. In this case, the power conversion unit 30c controls the driving of the motor 3x while executing the temperature protection function based on the actual thermistor temperature. This makes it possible to prevent damage to the power conversion unit 30c having a heat source.

[0151] In addition, when the current value of the current of the motor 3x is equal to or greater than the switching threshold current 45 and the frequency of the current flowing through the motor 3x rises from below the switching threshold frequency 46 to a predetermined hysteresis threshold frequency 48 that is higher than the switching threshold frequency 46, i.e., when transitioning from the first case to the second case as shown by arrow 43, the control unit 10a continues to control the driving of the motor 3 by the power conversion unit 30 based on the control estimated temperature (see Figure 8).

[0152] In addition, the above statement "the current value of the current of motor 3x is equal to or greater than the switching threshold current 45, and the frequency of the current flowing through motor 3x rises from below the switching threshold frequency 46 to a preset hysteresis threshold frequency 48 that is higher than the switching threshold frequency 46" may be replaced with "the phase current value of the phase current of motor 3x is equal to or greater than the switching threshold current, and the rotation speed of motor 3x rises from below the switching threshold rotation speed to a preset hysteresis threshold rotation speed that is higher than the switching threshold rotation speed."

[0153] When transitioning from the first case to the second case as indicated by arrow 43, it takes time for the temperature to converge, so the detected temperature of the thermistor S may not be able to adequately track the temperature of the heat source Z. In this case, the power conversion unit 30c controls the driving of the motor 3x while executing the temperature protection function based on the above-mentioned estimated control temperature. This makes it possible to prevent damage to the power conversion unit 30c having a heat source.

[0154] On the other hand, when the current value of the current of motor 3x is equal to or greater than the switching threshold current 45 and the frequency of the current flowing through motor 3 decreases from equal to or greater than the hysteresis threshold frequency 48 to the switching threshold frequency 46, i.e., when transitioning from the above-mentioned second case to the first case as shown by arrow 44, the control unit 10a continues to control the driving of motor 3 by the power conversion unit 30 based on the actual thermistor temperature (actual temperature) 50 (see Figure 8). In addition, the above statement "the current value of the current of motor 3x is equal to or greater than the switching threshold current 45, and the frequency of the current flowing through motor 3 decreases from equal to or greater than the hysteresis threshold frequency 48 to the switching threshold frequency 46" may be replaced with "the phase current value of the phase current of motor 3x is equal to or greater than the switching threshold current, and the rotation speed of motor 3x decreases from equal to or greater than the hysteresis threshold rotation speed to the switching threshold rotation speed."

[0155] When the transition occurs from the second case to the first case as indicated by arrow 44, the temperature rise is rapid, so the temperature detected by the thermistor S can adequately track the temperature of the heat source Z. In this case, the power conversion unit 30c controls the driving of the motor 3x while executing the temperature protection function based on the actual thermistor temperature. This makes it possible to prevent damage to the power conversion unit 30c having a heat source.

[0156] (Third embodiment) In the second embodiment described above, the heat source Z is a transistor of the bridge circuit X of the power conversion unit 30c. However, it is also possible that the heat source Z is a coil of the motor 3x. Therefore, a third embodiment in which the heat source Z is a coil of the motor 3x will be described with reference to FIG. 9. The third embodiment is similar to the second embodiment except that the heat source Z is a coil of the motor 3x.

[0157] 9, the heat source Z is the coils L1, L2, and L3 of the motor 3x. In the example of FIG. 9, the transistors Q1 to Q6 of the driver circuit X are also described as the heat source Z, similarly to the second embodiment.

[0158] The thermistors S are arranged adjacent to the coils L1, L2, and L3. That is, the first thermistor S1a is arranged adjacent to the coil L1, which is a heat source. The second thermistor S2a is arranged adjacent to the coil L2, which is a heat source. The third thermistor S3a is arranged adjacent to the coil L3, which is a heat source.

[0159] In this embodiment, for example, the temperature value of the first phase coil of motor 3x may be substituted by the average value of the temperature detection value of a second thermistor Sa2 arranged in the vicinity of the second phase coil of motor 3x and the temperature detection value of a third thermistor Sa3 arranged in the vicinity of the third phase coil of motor 3x.

[0160] This makes it possible to omit the first thermistor Sa1.

[0161] In this embodiment, if necessary, the higher of the actual thermistor temperature detected by the thermistor S and the control estimated temperature may be selected for driving the motor.

[0162] According to this embodiment, taking into account the effects of thermal conduction and ambient temperature, the temperature of the heat source (the transistors of the power conversion unit (inverter circuit) or the coil of the motor) can be estimated based on the temperature detected by the thermistor, the motor current and frequency or rotation speed, and the temperature protection function can be performed. [Explanation of symbols]

[0163] 1 Control device 2 current source 3 Drive unit 5 Input section 8. Load 10 Control section 11 Temperature detection section 20 Memory section 30 Power conversion section

Claims

1. A drive unit that drives a load; a power conversion unit that converts power from a current source and supplies the power to the drive unit; a temperature detection unit that detects a temperature in the vicinity of a heat source generated by the power conversion unit or the drive unit; a control unit that controls the power conversion unit so as to output, from the drive unit, a torque determined based on a command signal input from a torque input unit and a temperature obtained based on a detection result of the temperature detection unit; Equipped with The vicinity of the heat source includes a distance from the heat source to a position where a temperature due to heat generated from the heat source can be detected, The control unit is When the temperature obtained based on the detection result is equal to or higher than a preset limit threshold and is lower than a preset abnormality threshold higher than the limit threshold, the power conversion unit is controlled so that a limit torque smaller than a command torque corresponding to the command signal is output from the drive unit. a storage unit configured to store a target limit torque table that associates a frequency of a current flowing through the drive unit with a target limit torque when the temperature obtained based on the detection result is equal to the limit threshold value, A target limit torque table stored in the storage unit is referenced to set the limit torque so that the limit torque is equal to or greater than the target limit torque corresponding to the frequency. A drive device characterized by:

2. The control unit is When the temperature obtained based on the detection result is equal to or higher than the abnormality threshold, the power conversion unit is controlled so that the torque output from the drive unit becomes zero.

2. The drive device according to claim 1 .

3. The control unit is When the temperature obtained based on the detection result is a normal state below the limit threshold, the power conversion unit is controlled so that a command torque corresponding to the command signal is output from the drive unit.

3. The drive device according to claim 1 or 2.

4. The control unit in the restricted state Acquire a frequency of a current flowing through the drive unit; The target limit torque table stored in the storage unit is referenced to set the limit torque so that the limit torque is equal to or greater than the target limit torque corresponding to the acquired frequency.

4. The drive device according to claim 1, wherein the drive device is a drive unit.

5. The control unit in the restricted state calculating a temperature difference value by multiplying a value obtained by subtracting the limit threshold value from the temperature obtained based on the detection result by a positive adjustment coefficient; Acquire a frequency of a current flowing through the drive unit; calculating a target limit torque corresponding to the acquired frequency by referring to the target limit torque table stored in the storage unit; calculating a negative cut torque to be subtracted from the command torque by multiplying a value obtained by subtracting a current torque currently output by the drive unit from the calculated target limit torque by the temperature difference value; Calculating the limit torque by adding the negative cut torque to the command torque; The power conversion unit is controlled so that the limit torque is output from the drive unit.

4. The drive device according to claim 1, wherein the drive device is a drive unit.

6. The target limit torque table is set so that the target limit torque increases as the frequency of the current flowing through the drive unit increases, and the target limit torque decreases as the frequency of the current flowing through the drive unit decreases.

6. The drive device according to claim 1, wherein the drive device is a drive unit.

7. The temperature obtained based on the detection result is a control estimated temperature obtained by the control unit, the storage unit stores a saturation temperature information table in which a combination of a current value flowing in the drive unit and a frequency of the current flowing in the drive unit is associated with a saturation temperature that is a maximum temperature at which the heat of the heat source is saturated; The control unit is A current value flowing in the drive unit is obtained, and a frequency of the current flowing in the drive unit is obtained; a step a of calculating a current saturation temperature of the heat source corresponding to a combination of the current value and the frequency by referring to the saturation temperature information table stored in the storage unit; A step c of calculating a current estimated heat source temperature by estimating the temperature of the heat source by using the current saturation temperature and a first coefficient; A step e of calculating a current estimated detection unit temperature by estimating a temperature in the vicinity of the heat source by using the current estimated heat source temperature and a second coefficient; a step f of acquiring an actual temperature detected by the temperature detection unit; a step g of calculating a temperature difference by subtracting the actual temperature from the current estimated detection portion temperature; a step h of calculating a temperature correction value by multiplying the temperature difference by a preset temperature correction coefficient; a step i of calculating a control estimated temperature by adding the temperature correction value to the current estimated heat source temperature; The vicinity of the heat source includes a distance from the heat source to a position where a temperature due to heat generated from the heat source can be detected, The current estimated heat source temperature in the c step is When the current saturation temperature is equal to or higher than the past estimated heat source temperature, and when the temperature difference obtained by subtracting the past estimated heat source temperature from the current saturation temperature is equal to or higher than the first P threshold, the first coefficient is set as a first P coefficient and calculated by the following formula 31: When the current saturation temperature is equal to or higher than the past estimated heat source temperature, and when the temperature difference obtained by subtracting the past estimated heat source temperature from the current saturation temperature is less than the first P threshold, the first coefficient is set to a second P coefficient smaller than the first P coefficient, and is calculated by the following formula 32: When the current saturation temperature is lower than the past estimated heat source temperature, and when the temperature difference obtained by subtracting the past estimated heat source temperature from the current saturation temperature is equal to or less than the first N threshold, the first coefficient is set to a first N coefficient and calculated by the following formula 33: When the current saturation temperature is lower than the past estimated heat source temperature, and when the temperature difference obtained by subtracting the past estimated heat source temperature from the current saturation temperature is greater than the first N threshold, the first coefficient is set to a second N coefficient smaller than the first N coefficient, and is calculated by the following formula 34: The past estimated heat source temperature is a temperature calculated a first time ago by a calculation method similar to a calculation method of a current estimated heat source temperature, The current estimated detection portion temperature in the step e is When the current estimated heat source temperature is higher than the past estimated detection unit temperature, and when the temperature difference obtained by subtracting the past estimated detection unit temperature from the current estimated heat source temperature is equal to or greater than the second P threshold, the second coefficient is set as a third P coefficient and calculated by the following formula 41: When the current estimated heat source temperature is higher than the past estimated detection unit temperature, and when the temperature difference obtained by subtracting the past estimated detection unit temperature from the current estimated heat source temperature is less than the second P threshold, the second coefficient is set to a fourth P coefficient smaller than the third P coefficient, and is calculated by the following formula 42: When the current estimated heat source temperature is equal to or lower than the past estimated detection unit temperature, and when the temperature difference obtained by subtracting the past estimated detection unit temperature from the current estimated heat source temperature is equal to or lower than the second N threshold value, the second coefficient is set to a third N coefficient and calculated by the following formula 43: When the current estimated heat source temperature is equal to or lower than the past estimated detection unit temperature, and when the temperature difference obtained by subtracting the past estimated detection unit temperature from the current estimated heat source temperature is greater than a second N threshold value, the second coefficient is set to a fourth N coefficient smaller than the third N coefficient, and is calculated by the following formula 44: The past estimated detector temperature is a temperature calculated in the first time period before by a calculation method similar to that of the current estimated detector temperature.

7. A drive device according to claim 4, wherein the drive device is a drive unit. Current estimated heat source temperature = First P coefficient × (current saturation temperature - previous estimated heat source temperature) + previous estimated heat source temperature ... (Equation 31) Current estimated heat source temperature = Second P coefficient × (current saturation temperature - previous estimated heat source temperature) + previous estimated heat source temperature ... (Equation 32) Current estimated heat source temperature = 1st N coefficient × (current saturation temperature - past estimated heat source temperature) + past estimated heat source temperature ... (Equation 33) Current estimated heat source temperature = Second N coefficient × (current saturation temperature - past estimated heat source temperature) + past estimated heat source temperature ... (Equation 34) Current estimated detector temperature = third P coefficient × (current estimated heat source temperature - past estimated detector temperature) + past estimated detector temperature ... (Equation 41) Current estimated detector temperature = fourth P coefficient × (current estimated heat source temperature - past estimated detector temperature) + past estimated detector temperature ... (Equation 42) Current estimated detector temperature = 3rd N coefficient × (current estimated heat source temperature - past estimated detector temperature) + past estimated detector temperature ... (Equation 43) Current estimated detector temperature = 4th N coefficient × (current estimated heat source temperature - past estimated detector temperature) + past estimated detector temperature ... (Equation 44)

8. the step a, the step c, the step e, and the step i are repeated at each first time; The steps f, g, and h are repeated every second time period that is longer than the first time period. The control device according to claim 7 .

9. The first coefficient is a value greater than 0 and less than 1, and the second coefficient is a value greater than 0 and less than 1.

9. The control device according to claim 7 or 8.

10. The control unit is When the value of the current flowing through the drive unit is less than a preset switching threshold current, or when the frequency of the current flowing through the drive unit is equal to or greater than a preset switching threshold frequency, the temperature obtained based on the detection result is regarded as the actual temperature detected by the temperature detection unit, rather than the estimated temperature for control.

10. The drive arrangement according to claim 7, wherein the drive arrangement is a drive mechanism.

11. When the temperature obtained based on the detection result becomes equal to or higher than the abnormal threshold value, the control unit stops the drive unit and does not resume control of the drive unit until the operation of the control unit is reset.

11. The drive device according to claim 1 .

12. A control method for controlling a power conversion unit that converts power from a current source and supplies power to a drive unit, comprising: when a temperature obtained based on a detection result by a temperature detection unit arranged near a heat source generated by the power conversion unit or the drive unit is equal to or higher than a preset limit threshold and is in a limited state below a preset abnormality threshold that is higher than the limit threshold, the power conversion unit is controlled so that a limit torque smaller than a command torque corresponding to a command signal input from a torque input unit is output from the drive unit, When the limit state is reached, a frequency of a current flowing through the drive unit is acquired; With reference to a target limit torque table stored in a storage unit, the limit torque is set to be equal to or greater than the target limit torque corresponding to the acquired frequency; the target limit torque table associates a frequency of a current flowing through the drive unit with the target limit torque when the temperature obtained based on the detection result is equal to the limit threshold value, The vicinity of the heat source includes the distance from the heat source to a position where the temperature due to heat generated by the heat source can be detected. A control method comprising:

13. The control method includes: When the temperature obtained based on the detection result is equal to or higher than the abnormality threshold, the power conversion unit is controlled so that the torque output from the drive unit becomes zero.

13. The control method according to claim 12.

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