JP2002370660A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering device capable of maintaining a superior steering feeling by properly limiting an indicator current according to ambient temperature when limiting the indicator current to a steering assisting force generating motor for preventing an overload. SOLUTION: The upper limit value of the indicator current to the steering assisting force generating motor is limited according to a limiting condition preset by a control device. When a detecting temperature by a temperature sensor of the ambient temperature of the motor exceeds a preset value, and a vehicle travels by exceeding predetermined preset time, a virtual ambient temperature set lower than the detecting temperature is set as the ambient temperature. When the detecting temperature by the temperature sensor exceeds the preset value, and the vehicle does not travel by exceeding the predetermined preset value, and when the detecting temperature by the temperature sensor is the preset value or less, the detecting temperature is set as the ambient temperature. The limiting condition is relieved as the preset ambient temperature becomes low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus for generating a steering assist force by an electric motor.

[0002]

2. Description of the Related Art In an electric power steering apparatus,
In order to prevent the electric motor for generating the steering assist force from being overheated due to overload, the upper limit value of the command current to the motor is limited according to a preset restriction condition.

For example, as a limiting condition, a set value of a variable corresponding to a motor load, such as a continuous driving time of the motor at the start of the limit and an integrated value of a supplied current, is determined in advance, and when the variable reaches the set value, By reducing the upper limit of the command current, overheating of the motor and the control device is prevented. When determining the limiting condition, the amount of increase in the ambient temperature when the motor is loaded is estimated, and the continuous driving time during which the motor does not overheat and the integrated value of the energizing current are determined in advance.

[0004]

Heretofore, when determining the limiting conditions, it has been assumed that the ambient temperature is the highest temperature in the specifications of the motor. Then, when the actual ambient temperature is lower than the assumed ambient temperature used for determining the limiting condition, the current value indicated to the motor is excessively limited. Therefore, the steering assist force is insufficient and the steering feeling is reduced.

Accordingly, it has been proposed by the present inventors that a temperature sensor capable of detecting the ambient temperature of the motor is provided, and the limiting condition is relaxed as the ambient temperature becomes lower. However, when the temperature sensor is arranged in a closed space such as in the housing of the motor control device, heat is accumulated in the space where the temperature sensor is arranged due to heat generated by the control device. Then, the temperature detected by the temperature sensor becomes
In a normal running state of the vehicle, the ambient temperature exceeds a value that can be taken, the ambient temperature cannot be accurately detected, and the meaning of providing the temperature sensor is lost.

[0006]

SUMMARY OF THE INVENTION An electric power steering apparatus according to the present invention includes a control device for limiting an upper limit value of a command current to an electric motor for generating a steering assist force of a vehicle in accordance with a preset limit condition. A temperature sensor for detecting an ambient temperature of the electric motor, and means for determining whether a temperature detected by the temperature sensor exceeds a predetermined set value,
Means for determining whether or not the vehicle has traveled beyond a predetermined set time, the temperature detected by the temperature sensor exceeds the set value, and the vehicle has traveled beyond the set time. If there is, a virtual atmosphere temperature set lower than the detected temperature is set as the atmosphere temperature,
If the temperature detected by the temperature sensor exceeds the set value, and the vehicle has not traveled for more than a predetermined set time, and if the temperature detected by the temperature sensor is equal to or less than a predetermined set value, The detected temperature is set as the ambient temperature, and the limiting condition is set such that the lower the set ambient temperature is, the more the temperature is relaxed. According to the configuration of the present invention, when limiting the upper limit value of the command current to the electric motor for preventing overload, the limitation can be performed according to the set ambient temperature. As a result, the command current is prevented from being excessively limited, and a decrease in steering feeling can be suppressed. If the temperature detected by the temperature sensor exceeds a predetermined value even though the vehicle is running for a predetermined time, the virtual atmosphere temperature lower than the detected temperature is changed to the ambient temperature. And the restriction condition is set.
Thereby, even when the temperature detected by the temperature sensor exceeds the ambient temperature that can be taken in the normal running state of the vehicle, the limiting condition can be appropriately relaxed.

It is preferable that the virtual atmosphere temperature is set to the above-mentioned set value. As a result, the limiting condition can be reliably alleviated based on the ambient temperature that can be taken in the normal running state of the vehicle.

[0008] Preferably, the predetermined set time is set to zero, and the virtual atmosphere temperature is set so as to decrease over time. As a result, if the vehicle is running for a short period of time, the restriction condition can be relaxed, and the set ambient temperature is reduced with the passage of time.
The restriction condition is not excessively relaxed.

[0009] Preferably, the temperature sensor is disposed in a housing of the control device. Thereby, even if the control device generates heat, the restriction condition can be appropriately relaxed.

The limiting conditions include a reference current corresponding to the integrated value of the current supplied to the motor at the start of the limit, a minimum value of the upper limit of the indicated current, and a maximum value after the upper limit of the indicated current is reduced. When the integrated value of the supplied current exceeds the square value of the reference current, a decrease from the maximum value of the upper limit value of the indicated current is started, and the supplied current is increased. When the integrated value exceeds the square of the minimum value of the upper limit value of the indicated current, the upper limit value of the indicated current is set to the minimum value, and thereafter, is increased to the maximum value at the increasing speed, and the reference current is set. The minimum value of the upper limit of the indicated current is increased as the set ambient temperature is lowered, and the increasing speed is increased as the set ambient temperature is lowered. Be killed It is preferred. This limits the upper limit of the command current to the motor to prevent overload.
The temperature can be properly set according to the set ambient temperature.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an electric power steering apparatus 1 shown in FIG. 1, a steering shaft 2 connected to a steering wheel H of a vehicle is connected to wheels 4 via a steering gear 3. The steering gear 3 is a rack and pinion type in this embodiment,
The steering shaft 2 is connected to a pinion 6 via a universal joint 5, and wheels 4 are connected to a rack 7 meshing with the pinion 6 via a link mechanism. Thereby, the rotation of the steering wheel H is transmitted to the rack 7 via the steering shaft 2 and the pinion 6.
The steering is performed by changing the toe angle of the wheel 4 due to the movement of the rack 7. The steering gear 3 only needs to be able to transmit the movement of a member operated by the driver's steering to the wheels such that the steering angle changes, and may be, for example, a ball screw type.

The output of the electric motor 10 for generating a steering assist force is transmitted to the wheels 4 via an output transmission mechanism. The output transmission mechanism has a driven gear 11 provided on the steering shaft 2 and a drive gear 12 meshed with the driven gear 11, and the drive gear 12 is driven by the motor 10 to generate a steering assist force. I do. The output transmission mechanism controls the output of the motor 10 so that the steering angle changes.
For example, a screw integrated with a rack of a rack and pinion type steering gear and a nut screwed to the screw may be used, and the nut may be driven by the motor 10.

As a steering assist reference value for determining the steering assist force, a torque sensor 21 for detecting a steering torque transmitted by the steering shaft 2 and a vehicle speed sensor 22 for detecting a vehicle speed are connected to an on-vehicle control device 23. Have been. Note that the steering assist reference value is not particularly limited as long as it is a reference for determining the steering assist force. For example, a steering angle may be employed.

A current detection sensor 25 for detecting a current value of the motor 10 and a temperature sensor 26 for detecting an ambient temperature of the motor 10 are connected to the control device 23.
In the present embodiment, the temperature sensor 26 is disposed in the housing 23a of the control device 23.
What is necessary is just to arrange | position at the position which can detect 0 atmosphere temperature.

The control device 23 includes the torque sensor 2
An instruction current value is calculated in accordance with the steering torque detected by step 1 and the vehicle speed detected by the vehicle speed sensor 22. That is, the control device 23 stores a preset relationship between the steering torque, the vehicle speed, and the command current value, and calculates the command current value from the stored relationship, the detected steering torque, and the vehicle speed. The stored relationship is determined, for example, such that the steering assist force increases as the steering torque increases and the vehicle speed decreases. The control device 23 has a built-in switching element that opens and closes a power supply path from the battery to the motor 10, calculates a deviation between the current value detected by the current detection sensor 25 and the calculated instruction current value, and calculates the deviation. The command voltage is determined to eliminate the deviation, and the switching element is set to P
An instruction voltage corresponding to the instruction current obtained by performing the WM control is output to the motor 10.

The control device 23 stores limiting conditions for limiting the upper limit value of the command current to the motor 10,
The upper limit value of the command current to motor 10 is limited according to the limiting condition. The limiting condition is set in advance so that overheating of the motor 10 due to overload can be prevented.

In this embodiment, when the integrated value of the energizing current Im of the motor 10 exceeds the square value of the predetermined reference current Ia, the upper limit value of the indicated current is reduced from the maximum value Imax to the minimum value Imin. To start that. Further, when the integrated value becomes less than the square of the predetermined minimum value Imin of the upper limit value of the instruction current, the controller starts to increase the upper limit value of the instruction current from the minimum value Imin to the maximum value Imax. As the limiting conditions, the reference current Ia, the minimum value Imin of the upper limit of the indicated current, and the upper limit of the indicated current are set to the minimum value.
The increase speed when increasing from Imin to the maximum value Imax is set in advance. The maximum value Imax of the upper limit value of the command current is determined in advance from the specification of the motor 10 according to the maximum steering assist force required by the electric power steering device 1. The limiting condition and the maximum value Imax of the upper limit value of the command current are stored in the control device 23.

Here, the integrated value of the energizing current Im correlates with the heat generation amount of the motor 10, and the heat generation amount of the motor 10 correlates with the square of the energizing current Im. Therefore, M is determined by the conduction current I
integrated value of m, Laplace operator and s, as a transfer function of G (s), by M = G (s) · Im 2 can be obtained an integrated value of electric current Im to approximately. In the present embodiment, assuming that G (s) = 1 / {(1000 + s) · s}, the integrated value M of the conduction current Im = Im ² / {(1000 + s)}.
S}, and when the integrated value M exceeds the square value of the reference current Ia, that is, Im ² / ｛(1000 + s).
When s｝> Ia ² , the limitation of the upper limit value of the command current is started. Note that the transfer function G (s) is an example, and any transfer function G (s) may be used as long as the integrated value of the conduction current Im can be approximately obtained. The square value of the reference current Ia is determined as follows. The motor 10 is energized when the motor 10 is continuously driven for an allowed time ta while the maximum value Imax of the upper limit of the indicated current is energized at a predetermined ambient temperature. It is determined so as to correspond to the integrated value of the current. The minimum value Imin of the upper limit value of the command current is set such that continuous driving of the motor 10 is allowed at a predetermined atmospheric temperature while the minimum value Imin is energized. At the predetermined ambient temperature, the upper limit of the indicated current is the minimum value
In the state of Imin, the motor 10 can be driven continuously if the square value of the conduction current Im correlated to the heat generation amount of the motor 10 becomes smaller than the square value of the minimum value Imin of the upper limit of the command current. . Therefore, in the present embodiment, when the integrated value M of the conduction current Im correlated with the heat generation amount of the motor 10 becomes less than the square of the minimum value Imin of the upper limit value of the indicated current, the upper limit value of the indicated current is reduced. To release the limit, set the upper limit of the indicated current from the minimum value Imin to the maximum value.
Start increasing to Imax.

The limiting condition is set so that the lower the set ambient temperature of the motor 10, the more the temperature is reduced. That is, the reference current Ia corresponding to the allowable continuous driving time ta of the motor 10 and the minimum value Im of the upper limit value of the indicated current.
In is increased as the set ambient temperature is lower. Further, the increasing speed is increased as the set ambient temperature is lower.

FIG. 2 shows an example of the stored limiting condition. In this embodiment, the limiting condition is as follows.
The set atmosphere temperature is less than 25 ° C, 25 ° C to 30 ° C,
30 ° C to 35 ° C, 35 ° C to 40 ° C, 40 ° C to 45 ° C, 4
5 ° C to 50 ° C, 50 ° C to 55 ° C, 55 ° C to 60 ° C, 60
For each of the reference temperature ranges of ° C to 65 ° C, 65 ° C to 70 ° C, and 70 ° C or higher, the temperature is preset and stored in the control device 23.
That is, the maximum value Im of the upper limit value of the instruction current to the motor 10
The reference current Ia associated with the allowable continuous drive time ta of the motor 10 at ax (65 amps in the present embodiment), the minimum value Imin of the upper limit of the instruction current to the motor 10, and the upper limit of the instruction current are The increase speed Vi when increasing from the minimum value Imin to the maximum value Imax is stored for each reference temperature range of the set atmosphere temperature.

FIG. 3 shows an example of the relationship between the allowable continuous drive time ta of the motor 10 and the upper limit value of the command current to the motor 10. In the illustrated example, the set ambient temperature is less than 25 ° C. The maximum value Imax of the upper limit value of the indicated current is 6
5 amps.

FIG. 4 shows an example of the relationship between the upper limit value of the command current to the motor 10 and the integrated value M of the energizing current. When the integrated value M is the square value of the reference current Ia, the upper limit value is the maximum value.
When the integrated value M is the square value of the minimum value Imin of the upper limit, the upper limit becomes the minimum value Imin. In the present embodiment, the upper limit value of the indicated current is obtained by linear interpolation until the integrated value M exceeds the square value of the reference current Ia and reaches the square value of the minimum value Imin of the upper limit value. It is assumed that the upper limit value of the command current gradually decreases. In the illustrated example, the set atmosphere temperature is less than 25 ° C., and its maximum value Imax
Is 65 amps. In the example of FIG. 2, when the ambient temperature is equal to or higher than 65 ° C., the minimum value Imin of the upper limit of the command current is smaller than the reference current Ia. In such a case, when the integrated value M exceeds the square value of the reference current Ia, the upper limit value of the indicated current does not gradually decrease from the maximum value Imax but immediately becomes the minimum value Imin.

FIG. 5 shows an example of the relationship between the upper limit value of the command current and the time when the upper limit value of the command current to the motor 10 is increased from the minimum value Imin to the maximum value Imax. Ambient temperature is less than 25 ° C, its maximum value Im
ax is set to 65 amps.

The control procedure of the motor 10 by the control device 23 will be described with reference to the flowchart of FIG. First, the ambient temperature of the motor 10 is set (the reference temperature range in FIG. 2 is set) (step 1), and the value of the energizing current Im of the motor 10 detected by the current detection sensor 25 is read (step 2). Next, the integrated value M of the supplied current Im is calculated as M = Im ² / {(1000 + s) · s} (Step 3), and it is determined whether or not the integrated value M is equal to or less than the square of the reference current Ia (Step 4). ). If the integrated value M is equal to or less than the square value of the reference current Ia, the process returns to step 1. When the integrated value M exceeds the square value of the reference current Ia, for example, as shown in FIG. 4, the current is supplied between the minimum value Imin and the maximum value Imax of the upper limit value of the command current corresponding to the set ambient temperature. The upper limit of the command current of the motor 10 is reduced according to the relationship between the integrated value M of the current Im and the upper limit of the command current (step 5). Next, it is determined whether or not the upper limit value of the command current has reached the minimum value Imin (step 6), and if not, the process returns to step 5. If the upper limit value of the command current reaches the minimum value Imin, the upper limit value of the command current to the motor 10 is increased from the minimum value Imin to the maximum value Imax at the increase speed Vi corresponding to the set ambient temperature ( Step 7). Next, the upper limit value of the indicated current is equal to the maximum value Imax.
Is determined (step 8), and the maximum value Imax
If not, the process returns to step 7. If the upper limit value of the indicated current reaches the maximum value Imax, it is determined whether or not to end the control (step 9), and if not, the process returns to step 1. The end of the control is determined based on, for example, whether or not an ignition key switch of the vehicle is off.

The procedure for setting the ambient temperature of the motor 10 in the control step 1 of the motor 10 will be described with reference to the flowchart of FIG. First, the detected temperature T of the temperature sensor 26 is read (step 101). Next, the temperature T detected by the temperature sensor 26 is determined in advance and the control device 2
It is determined whether the set value α exceeds the set value α stored in Step 3 (Step 102). The set value α is set to the upper limit of the value that the ambient temperature can take in the normal running state of the vehicle. For example, in the normal running state of the vehicle, the temperature of the passenger compartment is reduced to a temperature below which the occupant can endure by opening the window of the vehicle to take in the outside air or operate the air conditioner, so that the ambient temperature is also reduced. It will correspond to the temperature in the cabin. Therefore, the set value α is determined based on the upper limit of the temperature at which a human can operate, and is set to, for example, 55 ° C. If the detected temperature T exceeds the set value α in step 102, it is determined whether or not the vehicle has been running for longer than the set time t1 previously stored in the control device 23 (step 103). In the present embodiment, the set time t1 is determined by the heat generated by the control device 23 while the vehicle is stopped.
When the ambient temperature of 0 rises above the set value α, the ambient temperature is determined based on the time required for the ambient temperature to decrease to the set value α in the normal running state of the vehicle, and is set to, for example, 15 minutes. In this embodiment, whether or not the vehicle is running is determined based on whether or not the vehicle speed V detected by the vehicle speed sensor 22 exceeds zero. However, the present invention is not limited to this. Then, it may be determined whether the clutch for power transmission from the engine to the wheels is in the connected state, or whether the vehicle is traveling by detecting the wheel speed. In step 103, the vehicle is set for a set time t1.
When the vehicle travels beyond the predetermined temperature, the virtual ambient temperature set lower than the detected temperature T is set as the ambient temperature of the motor 10. In the present embodiment, the virtual atmosphere temperature is set to the set value α (step 104). If the detected temperature T is equal to or less than the set value α in step 102, and if the detected temperature T exceeds the set value α and the vehicle does not travel for more than the set time t1 in step 103, the detected temperature T Is set as the ambient temperature (step 105).

According to the above configuration, when the upper limit value of the command current to the motor 10 is limited in order to prevent overload, the limitation can be performed according to the set ambient temperature.
As a result, the command current is prevented from being excessively limited, and a decrease in steering feeling can be suppressed. And, despite the fact that the vehicle is traveling beyond the set time t1,
When the temperature T detected by the temperature sensor 26 exceeds the set value α, the limiting condition is set by assuming that the virtual ambient temperature lower than the detected temperature T is the ambient temperature of the motor 10. Thereby, the temperature T detected by the temperature sensor 26 is obtained.
However, even when the ambient temperature exceeds the possible ambient temperature in the normal running state of the vehicle, the limiting condition can be appropriately relaxed. Further, by setting the virtual atmosphere temperature to the set value α, the limiting condition can be reliably alleviated based on the atmosphere temperature that can be taken in the normal running state of the vehicle. By arranging the temperature sensor 26 in the housing 23a of the control device 23, even if the control device 23 generates heat, the limiting condition can be appropriately relaxed.

The present invention is not limited to the above embodiment. A modified example of the procedure for setting the ambient temperature of the motor 10 in the control step 1 of the motor 10 in the above embodiment will be described with reference to the flowchart of FIG. The same parts as those in the above embodiment are denoted by the same reference numerals. First, the temperature sensor 2
The detected temperature T of Step 6 is read (Step 201). next,
It is determined whether the temperature T detected by the temperature sensor 26 exceeds a predetermined value α stored in the control device 23 in advance (step 202). The set value α is set in the same manner as in the above embodiment. If the detected temperature T exceeds the set value α, it is determined whether or not the vehicle has been running for longer than a predetermined set time (step 203). The set time is set to zero in this modification. Whether or not the vehicle is running is determined in the same manner as in the above embodiment. Step 203
If the vehicle is running in, it is determined whether the correction flag is on (step 204). Step 204
If the correction flag is not ON in step 20, the value obtained by subtracting the correction temperature δt previously set and stored in the control device 23 from the detected temperature T is replaced with the detected temperature T (step 20).
5). Thus, the first correction is performed after the detected temperature T first exceeds the set value α, and it is considered that the detected temperature T has decreased by the corrected temperature δt. The correction temperature δ
t is set so that the limiting condition does not suddenly change even if the ambient temperature of the motor 10 decreases by the correction temperature δt, and is set to 5 ° C. in this modification. Step 204
If the correction flag is ON, it is determined whether or not a predetermined time γ previously set and stored in the control device 23 has elapsed (step 206). The predetermined time γ is determined as follows: after the ambient temperature of the motor 10 rises due to the heat generated by the control device 23 when the vehicle is stopped, the vehicle travels, and the ambient temperature of the motor 10 decreases by the correction temperature δt in the normal traveling state of the vehicle. Is determined based on the time required for, for example, 5 minutes. If the predetermined time γ has elapsed,
A value obtained by subtracting the correction temperature δt from the currently set ambient temperature is replaced with the detected temperature T (step 20).
7). As a result, the second and subsequent corrections are performed after the detected temperature T first exceeds the set value α, and it is considered that the detected temperature T decreases by the correction temperature δt due to each correction. That is, when the detected temperature T exceeds the set value α, the detected temperature T is corrected so as to decrease as time passes. When the detected temperature T is corrected in Step 205 or Step 207, it is determined whether or not the corrected detected temperature T is equal to or lower than the set value α (Step 208). If the corrected detected temperature T is equal to or less than the set value α in step 208, the set value α is set as a virtual atmosphere temperature set lower than the detected temperature T.
Is set as the ambient temperature of the motor 10 (step 209), and then the correction flag is turned on (step 210). If the corrected detected temperature T exceeds the set value α in step 208, the corrected detected temperature T is set as the ambient temperature of the motor 10 as a virtual atmosphere temperature set lower than the detected temperature T (step 21).
1) Then, the correction flag is turned on (step 2)
10). As a result, the virtual atmosphere temperature is set so as to decrease with the passage of time.
Each time, the correction temperature δt is decreased. If the detected temperature T is equal to or lower than the set value α in step 202, and if the vehicle is not running in step 203, the correction flag is turned off (step 212), and the detected temperature T is set as the ambient temperature of the motor 10. (Step 21
3). Others are the same as the above embodiment.

According to the above modification, the same operation and effect as those of the above embodiment can be obtained. Further, when the temperature detected by the temperature sensor exceeds the set value, the vehicle can run for a short time. If the limiting condition can be relaxed, and the set atmospheric temperature is reduced with the passage of time, the limiting condition is not excessively relaxed.

[0029]

According to the present invention, when the command current to the motor for generating a steering assist force is limited to prevent an overload, a good steering feeling can be obtained by appropriately limiting the current according to the ambient temperature. An electric power steering device that can be maintained can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory diagram of an electric power steering device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a limiting condition stored in a control device in the electric power steering device according to the embodiment of the present invention.

FIG. 3 is an example of a relationship between a set value of a continuous driving time of the motor and an upper limit value of the instruction current to the motor at the start of the limitation of the upper limit value of the instruction current to the motor in the electric power steering apparatus according to the embodiment of the present invention. Figure showing

FIG. 4 is a diagram illustrating an example of a relationship between an integrated value of a current supplied to a motor and an upper limit of a command current to the motor in the electric power steering device according to the embodiment of the present invention;

FIG. 5 is a diagram showing an example of the relationship between the upper limit value of the command current and the time when increasing the upper limit value of the command current to the motor in the electric power steering device according to the embodiment of the present invention.

FIG. 6 is a flowchart showing a control procedure of a motor in the electric power steering device according to the embodiment of the present invention.

FIG. 7 is a flowchart showing a procedure for setting an ambient temperature in the electric power steering device according to the embodiment of the present invention;

FIG. 8 is a flowchart showing a procedure for setting an ambient temperature in an electric power steering apparatus according to a modification of the present invention.

[Explanation of symbols]

 Reference Signs List 10 electric motor 23 control device 23a housing 26 temperature sensor

Claims (5)

[Claims] A control device for limiting an upper limit value of a command current to an electric motor for generating a steering assist force of a vehicle in accordance with a preset restriction condition; a temperature sensor for detecting an ambient temperature of the electric motor; Means for determining whether or not the temperature detected by the temperature sensor exceeds a predetermined set value, and means for determining whether or not the vehicle is running for more than a predetermined set time. If the detected temperature exceeds the set value and the vehicle is running for more than the set time, a virtual atmosphere temperature set lower than the detected temperature is set as the atmosphere temperature, and the detected temperature is detected by the temperature sensor. The temperature exceeds the set value, and
If the vehicle has not traveled for more than a predetermined set time, and if the temperature detected by the temperature sensor is equal to or less than a predetermined set value, the detected temperature is set as the ambient temperature, and the limiting condition is: An electric power steering device that is set so as to be relaxed as the set ambient temperature is lower. 2. The electric power steering apparatus according to claim 1, wherein the virtual atmosphere temperature is set to the set value. 3. The electric power steering apparatus according to claim 1, wherein the predetermined set time is set to zero, and the virtual atmosphere temperature is set so as to decrease as time elapses. 4. The electric power steering apparatus according to claim 1, wherein the temperature sensor is disposed in a housing of the control device. 5. As the limiting conditions, the reference current corresponding to the integrated value of the current supplied to the motor at the start of the limiting, the minimum value of the upper limit of the indicated current, and the upper limit of the indicated current are reduced. The increase speed at which the current is increased to the maximum value is set in advance, and when the integrated value of the supplied current exceeds the square value of the reference current, the reduction of the upper limit of the indicated current from the maximum value is started, and When the integrated value of the current exceeds the square value of the minimum value of the upper limit value of the instruction current, the upper limit value of the instruction current is set to the minimum value, and thereafter, the reference current is increased to the maximum value at the increasing speed. The lower the set ambient temperature, the higher the lower the set ambient temperature, the greater the minimum value of the upper limit of the indicated current, and the higher the speed, the lower the set ambient temperature. Be faster The electric power steering apparatus according to any one among Motomeko 1-4.