JP5092553B2 - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance temperature estimating accuracy when the temperature of an object to be detected in temperature is estimated from an ambient temperature and a motor current. <P>SOLUTION: A maximum current value i of three-phase motor currents is square-multiplied to calculate an average value Wm. When an electric motor 8 is not rotated in a steering-held state, a temperature rise correction value &epsi;1 equivalent to a difference in temperature rise rate caused by electrification between a normal steering state and a steering-held state is added to the average value Wm. The value added for correction is processed by a filter 55, and a temperature rise amount &Delta;TPup caused by electrification is calculated. When a temperature sensor 17 is normal, the sum of a measured temperature TPr and the temperature rise amount &Delta;TPup caused by electrification is determined as an estimated temperature TPc. When the temperature sensor 17 is abnormal, an ambient temperature TPrr for estimation set to the maximum value adoptable as the ambient temperature of a motor relay 20 is added to the temperature rise amount &Delta;TPup caused by electrification, and the value obtained is determined as an estimated temperature TPc. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

The present invention relates to an electric power steering apparatus that applies a steering assist force to a steering mechanism of a vehicle .

Conventionally, as a method of estimating the temperature of the motor coil of an electric motor, the value of the current flowing in the motor coil is detected, and estimated from the sum of the temperature rise accompanying energization calculated from the detected value and the ambient temperature detected by the temperature sensor. (For example, refer to Patent Document 1), temperature estimation calculation is performed using the temperature detection value detected by the temperature sensor as an initial value for temperature estimation, and when a temperature sensor abnormality is detected, the temperature sensor is periodically stored in advance. A method in which temperature estimation is performed using the detection value of the temperature sensor before the occurrence of a malfunction that has occurred (see, for example, Patent Document 2), and the temperature of the motor coil increases during steering and during non-steering Considering this because the degree is different, a method is proposed in which the low-pass filter used for estimating the motor coil is switched (for example, see Patent Document 3).
JP 2005-204358 A JP 2006-44437 A JP 2003-284375 A

As described above, by adding the ambient temperature detected by the temperature sensor and the temperature increase due to energization calculated considering whether the electric motor is rotating or stopped, the motor coil The temperature can be estimated with high accuracy.
However, when an abnormality occurs in the temperature sensor, the detected value of the temperature sensor before that does not necessarily indicate a value corresponding to the actual ambient temperature, and may indicate a minimum value or a maximum value, for example. Also, when restarting by the user, depending on the stop time, the difference between the temperature before the abnormality occurred in the temperature sensor and the actual temperature may become large, and the detection value before the abnormality occurred in the temperature sensor is used. If the temperature is estimated, accurate temperature estimation may not be possible.

In addition, as described above, when the electric motor is in the rotating state or in the stopped state, in the calculation of the temperature rise, by changing the low-pass filter used for the calculation, various parameters are set. When this low pass filter is specified by setting, adjustment is difficult when there are a lot of parameters to be set, and other components of the motor system such as a motor relay are used instead of the motor coil. When performing temperature detection, it is necessary to set the parameters for both when the electric motor is rotating and when it is stopped. There has been a demand for a temperature detection device for a motor system capable of this.
Therefore, the present invention has been made paying attention to the above-mentioned conventional unsolved problems, and it is easy to estimate the temperature of not only the motor coil but also the components of the motor system inserted in the drive current conduction path to the electric motor. and its object is to provide a possible electric dynamic power steering GuSo location of doing and accurately.

In order to achieve the above object, an electric power steering apparatus according to claim 1 of the present invention includes an electric motor for generating a steering assist force, and a temperature at which the temperature of the component is detected in the motor system of the electric motor. the electric power steering apparatus equipped with a detection device, said temperature sensing device includes a phase current detecting means for detecting a phase current of the electric motor, the configuration of the electric motor and motor system that is arranged in the drive current supply paths Using the ambient temperature measuring means for measuring the ambient temperature of the temperature detection target component and the phase current detection value detected by the phase current detection means, the temperature associated with energization of the temperature detection target component A temperature that estimates an increase and estimates the temperature of the temperature detection target component from the sum of the temperature increase and the temperature measured by the ambient temperature measurement means Has a constant section, the said ambient temperature measuring means comprises a monitoring means for performing the abnormality monitoring, the temperature estimating means, when detecting an abnormality of the ambient temperature measuring means by said monitoring means, said ambient temperature In place of the temperature measurement value of the measuring means, the temperature of the component subject to temperature detection is estimated using the estimation ambient temperature preset for each component corresponding to the component subject to temperature detection. It is characterized by.

According to a second aspect of the present invention, there is provided an electric power steering apparatus comprising: a motor operating state detecting unit that detects whether the electric motor is in a rotating state or a stopped state; and a temperature increase estimated by the temperature estimating unit. The temperature increase is corrected by adding or subtracting a correction value for correcting the temperature increase rate caused by the operating state of the electric motor set in advance for each temperature detection target component to the calculated value in the calculation process of And a correcting means .

According to a third aspect of the present invention, there is provided the electric power steering apparatus according to the third aspect , wherein the temperature estimating unit calculates a mean of squared integrated values of the phase current detection values detected by the phase current detecting unit, and the square integrated unit. A filter unit for filtering the average value calculated by the average unit to estimate the temperature rise, and the correction unit is configured to calculate the average value calculated by the square integration average unit input to the filter unit. It is characterized by performing correction .

The electric power steering apparatus according to a fourth aspect is characterized in that the estimation ambient temperature is set to a value corresponding to a maximum value that the ambient temperature of the temperature detection target component can take.
Further, the electric power steering apparatus according to claim 5 includes a correction value calculation means for calculating a correction value for correcting the temperature increase rate difference of the temperature detection target component using the phase current detection value. It is characterized by.

An electric power steering device according to claim 1 of the present invention is a temperature detection device that detects the temperature of components in a motor system of an electric motor for generating a steering assist force . A temperature rise due to energization of the component is estimated, and the temperature of the temperature detection target component is estimated from this and the ambient temperature of the temperature detection target component.
At this time, when an abnormality is detected in the ambient temperature measuring means, the estimated ambient temperature set in advance for each component corresponding to the component whose temperature is to be detected is used instead of the temperature measurement value. Since the temperature of the component to be detected is estimated, the temperature can be estimated with high accuracy according to the temperature detection target.

According to the electric power steering apparatus of the second aspect , the electric motor that is preset for each component corresponding to this component in the calculation process for the temperature rise is in a rotating state. Since the correction value for error correction caused by the difference in the rate of temperature rise due to whether it is in a non-rotating state is added or subtracted to correct the temperature rise, considering the operating state of the electric motor, A more accurate estimated temperature can be obtained. In addition, it is possible to suppress the occurrence of errors due to the operating state of the electric motor simply by adding or subtracting the temperature increase correction value corresponding to the temperature detection target component. The detection accuracy can be easily improved without significantly changing the method of estimating the temperature from the current value and the ambient temperature. Moreover, even if the temperature detection target is changed, it can be easily handled by changing the correction value for temperature rise correction in accordance with the temperature detection target component and adding the correction value.
Further, according to the electric power steering device of the third aspect, after adding or subtracting the correction value for temperature increase correction according to the temperature detection target component to the average value calculated by the square integration average unit, Since the temperature rise is estimated by filtering, the square summation averaging unit can be made common regardless of the type of the temperature detection target component.

Further, according to the electric power steering apparatus according to claim 4, since the maximum value that the ambient temperature can take is set as the estimation ambient temperature for each component as the estimation ambient temperature. It is possible to avoid the estimated temperature calculated using the temperature being lower than the actual temperature of the component.
Further, according to the electric power steering apparatus according to claim 5, the correction value of the temperature increase rate difference for correction due to the operating state of the electric dynamic motor, it is so arranged to calculate on the basis of the current flowing through the electric motor Thus, correction can be performed using a correction value that is more practical, and a more accurate estimated temperature can be obtained.

Embodiments of the present invention will be described below.
First, a first embodiment will be described.
FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.
In the figure, reference numeral 1 denotes a steering wheel. A steering shaft 2 is connected to the steering wheel 1, and the steering shaft 2 is connected to a tie rod 6 of a steering wheel via universal joints 4a and 4b and a pinion rack mechanism 5. Yes.
The steering shaft 2 is provided with a torque sensor 7 that detects the steering torque of the steering wheel 1, and an electric motor 8 that assists the steering force applied to the steering wheel 1 is coupled via the reduction gear 3. Yes.

In addition, power is supplied from a battery 11 via an ignition key 12 and a power supply relay 13 to a control unit 10 configured by, for example, an MCU (Micro Controller Unit) that controls the power steering device. The control unit 10 includes a torque sensor 7. The steering assist control process is performed based on the steering torque T detected by the vehicle speed V and the vehicle speed V detected by the vehicle speed sensor 14, and the electric motor 8 generates a steering assist force corresponding to the steering torque T and the vehicle speed V. A steering auxiliary current command value I _M is calculated, and this steering auxiliary current command value I _M is output to a motor drive circuit 15 constituted by a switching element such as a field effect transistor, for example, whereby a current supplied to the electric motor 8 To control. Then, the drive current from the motor drive circuit 15 is supplied to the electric motor 8 via the motor relay 20. The control unit 10 detects the temperature of the motor relay 20 based on input signals from a motor current detection circuit 16 that detects each phase current of the electric motor 8 and a temperature sensor 17 that measures the temperature around the motor relay 20. and, when the temperature of the motor relay 20 is abnormal with respect to the steering assist current command value I _M, performs limit processing for suppressing the temperature rise of the motor relay 20.

FIG. 2 is a block diagram illustrating a functional configuration of the control unit 10. In FIG. 2, for example, the phase compensator 31 does not represent a phase compensator as independent hardware, but represents a phase compensation function as arithmetic processing executed by the arithmetic processing device, that is, software. Yes.
The function and action of the control unit 10 will be described. The steering torque T detected by the torque sensor 7 is phase-compensated by the phase compensator 31 for improving the stability of the steering system, and the phase-compensated steering torque T is This is input to the steering assist command value calculator 32. Further, the vehicle speed V detected by the vehicle speed sensor 14 and the motor rotation angle θ from the motor rotation angle sensor 8 a that detects the rotation angle of the rotor of the electric motor 8 are also input to the steering assist command value calculator 32.

Steering assist command value calculator 32, the input steering torque T, the vehicle speed V, and calculates the steering assist current command value I _M is a control target value of the current supplied to the electric motor 8 based on the motor rotation angle θ . The steering auxiliary command value calculator 32 and memory (not shown) is attached, this memory, the vehicle speed V as a parameter, and stores a steering assist current command value I _M which corresponds to the steering torque T The steering assist current command value _IM is set based on the stored data.

The steering assist current command value I _M is input to the subtractor 33 and is also input to the feedforward differential compensator 34 for increasing the response speed, and the output (I _M −I _MD ) of the subtractor 33 is proportionally calculated. Is input to the device 35.
The proportional output of the proportional calculator 35 is input to the adder 36 and also input to the integral calculator 37 for improving the characteristics of the feedback system. The output of the differential compensator 34 and the output of the integral calculator 37 are also added. The current control value E, which is an output of the current control value 36, is limited by the limit circuit 41 in accordance with a limit command from the temperature monitoring unit 42, and then input to the motor drive circuit 9. The motor current detection value I _MD of the electric motor 8 is detected by the motor current detection circuit 16, and the motor current detection value I _MD is subtracted from the steering auxiliary current command value I _M by the subtractor 33, thereby obtaining the steering auxiliary current. feedback control is performed so as to achieve the command value I _M.

The measured value TPr of the ambient temperature of the motor relay 20 measured by the temperature sensor 17 is input to the temperature estimation unit 43, and the temperature estimation unit 43 measures the measured temperature TPR and the motor current around the motor relay 20 from the temperature sensor 17. The temperature of the motor relay 20 is estimated using the detected three-phase motor current value detected by the detection circuit 16, and the estimated temperature TPc is output to the temperature monitoring unit 42.
Further, the temperature estimation unit 43 monitors abnormality of the temperature sensor 17 based on the measured temperature TPr of the temperature sensor 17, and when an abnormality of the temperature sensor 17 is detected, it is replaced with the motor relay in advance instead of the measured temperature TPr of the temperature sensor 17. The estimation ambient temperature TPrr set as the ambient temperature of 20 is used, and the temperature of the motor relay 20 is estimated using the estimation ambient temperature TPrr and the detected motor current value of each phase detected by the motor current detection circuit 16. This is output to the temperature monitoring unit 42 as the estimated temperature TPc.

  The temperature monitoring unit 42 monitors the estimated temperature TPc of the motor relay 20 estimated by the temperature estimating unit 43, and the estimated temperature TPc becomes equal to or higher than the overheat protection temperature for protecting the motor relay 20 set in advance from overheating. At this time, a restriction command is issued to the restriction circuit 41. The limiting circuit 41 performs a limiting process for avoiding overheating of the motor relay 20 by a known procedure, limits the current control value E, and reduces the energization amount of the motor relay 20 to avoid overheating of the motor relay 20. .

FIG. 3 is a functional block diagram of the temperature estimation unit 43.
The three-phase motor current detection values ia, ib, ic detected by the motor current detection circuit 16 are input to the maximum value detection unit 51, and the maximum value is selected from the three-phase phase currents. The detected maximum current value i is input to the square integration average unit 52, the average value Wm of the square integration value of the maximum current value i is calculated and then input to the adder 53, and the temperature rise correction value setting unit 54 is calculated. After the temperature increase correction value ΔTPε corresponding to the steering state of the electric motor 8 set in (5) is added, the temperature is corrected by the filter 55 and the energization temperature increase ΔTPup associated with energization is estimated. This energization temperature rise ΔTPup and the ambient temperature setting unit 56 add the ambient temperature TPa set according to whether or not the temperature sensor 17 is normal by an adder 57 and output this as the estimated temperature TPc.
Maximum current value i detected by the maximum value detector 51 is input to the square integrating unit 52a square integration average unit 52, as shown in the following equation (1), and energizing the maximum current value i ² which is square Integration (integration) is performed over time (t1 to t2).

Here, t1 and t2 indicate that the maximum current value i is energized from time t1 to time t2.
The integration amount W, which is the output of the square integration unit 52a, is input to the averaging unit 52b and averaged in the section (t2-t1). Then, the average value Wm that is the output of the averaging unit 52 a is output to the adder 53.

  The temperature rise correction value setting unit 54 sets the temperature rise correction value ΔTPε depending on whether the normal steering is being performed or the steering is being maintained. The determination of the steering state as to whether or not the normal steering is performed is determined based on whether or not the electric motor 8 is rotating. When the electric motor 8 is rotating, it is determined as the normal steering state, and the temperature rise correction value ΔTPε is Set to zero. On the other hand, when the electric motor 8 is in the non-rotating state, that is, when the electric motor 8 is in the non-rotating state even though the current is energized, it is determined that the steering is maintained, and the temperature increase correction value ΔTPε is the temperature increase of the motor relay 20. The motor relay correction value ε1 set as the correction value is set. Whether or not the electric motor 8 is rotating is determined based on the motor rotation angular velocity obtained by differentiating the motor rotation angle θ from the motor rotation angle sensor 8a.

The correction value ε1 for the motor relay is calculated when the temperature increase during steering is calculated using the filter 55 for calculating the temperature increase due to energization during normal steering. In other words, the error included in the temperature rise during the steering calculated by the filter process in the filter 55 caused by the difference in the temperature rise rate between when the electric motor 8 rotates and when it does not rotate is calculated. It is set to a value that can be offset.
The average value Wm corrected by the adder 53 is input to the first-order lag function portion (function = (1 / (1 + T1 · s)) 55a of the filter 55, and the output is input to the gain portion (gain K1) 55b. The intermediate value y is output.

Next, the intermediate value y is input to the adder 55c and the first-order lag function section (function = (1 / (1 + T2 · s)) 55d. Further, the output of the first-order lag function section 55d is the gain section (gain K2) is input to 55e, and the intermediate value z becomes the output of the gain section 55e.
The intermediate value z is input to the adder 55c, and the output y of the gain unit 55b and the intermediate value z are added by the adder 55c, and the energization temperature rise ΔTPup (= y + z) is output from the adder 55c. Is calculated as

  The ambient temperature setting unit 56 sets the ambient temperature TPa according to whether the temperature sensor 17 is in a normal state or a failure state. Specifically, based on the measured temperature TPr of the temperature sensor 17, for example, the abnormality of the temperature sensor 17 is detected based on whether or not the measured temperature TPr is a value within a normal range. If the temperature sensor 17 is normal, the measured temperature TPr of the temperature sensor 17 is set as the ambient temperature TPa. If the temperature sensor 17 is abnormal, the preset ambient temperature TPrr for the motor relay 20 is set as the ambient temperature TPa. The estimated ambient temperature TPrr for the motor relay 20 is set to a value corresponding to the maximum value of the temperature that can be taken as the ambient temperature of the motor relay 20 detected in advance through experiments or the like.

Next, the operation of the first embodiment will be described with reference to the flowchart of FIG. 4 showing an example of the processing procedure of the temperature estimation process executed by the control unit 10.
As shown in the functional block diagram of FIG. 2, the control unit 10 executes steering assist control processing based on the steering torque T detected by the torque sensor 7 and the vehicle speed V detected by the vehicle speed sensor 14, thereby steering assist current. The command value I _M is calculated, and the motor drive circuit 9 is operated so that a drive current corresponding to the steering assist current command value I _M is supplied to the electric motor 8, so that an optimum steering assist force is generated by the electric motor 8. This is transmitted to, for example, the steering shaft 2 to which the steering wheel 1 is connected or the pinion shaft 5 of the steering gear via the reduction gear 3, so that the steering wheel 1 can be steered with a light steering torque.

At this time, the temperature estimation unit 43 estimates the temperature of the motor relay 20, and the temperature monitoring unit 42 uses the estimated temperature TPc of the motor relay 20 estimated by the temperature estimation unit 43. We are monitoring.
As shown in FIG. 4, the temperature estimation unit 43 reads the three-phase motor current detection values ia to ic detected by the motor current detection circuit 16 (step S1), and selects the maximum value as the maximum current value i. (Step S2).

Then, according to the equation (1), the integrated value obtained by integrating (integral) over a squared maximum current value i ² of the energized time (t1 from t2) is calculated, which is averaged (step S3).
Subsequently, it is determined whether or not the electric motor 8 is rotating based on the motor rotation angular velocity obtained by differentiating the motor rotation angle θ from the motor rotation angle sensor 8a. If the electric motor 8 is rotating, the normal steering state is established. The process proceeds from step S4 to step S5, and the temperature rise correction value ΔTPε is set to zero. For this reason, zero is added as the temperature rise correction value ΔTPε (= 0) to the average value Wm of the square integration value, so that the correction of the average value Wm of the square integration value is not performed (step S6), and the average value of the square integration value A filtering process is performed on Wm, and an energization temperature increase ΔTPup associated with energization is calculated from an average value Wm of squared integrated values (step S7).

Next, it is determined whether or not the temperature sensor 17 is normal. If the temperature sensor 17 is normal, the process proceeds from step S8 to step S9, and the measured temperature TPr of the temperature sensor 17 is set as the ambient temperature TPa. The measured temperature TPr and the energization temperature increase ΔTPup calculated in step S7 are added and output to the temperature monitoring unit 42 as the estimated temperature TPc (step S10).
The temperature monitoring unit 42 monitors the estimated temperature TPc, limits the estimated temperature TPc is relative to the steering assist current command value I _M if overheating does not exceed the protection temperature for overheat protection of the motor relay 20 is not performed. Therefore, the electric motor 8, the steering assist current command value I _M corresponding steering assist force is supposed to be generated, so that the steering load on the driver is reduced.

On the other hand, when the estimated temperature TPc of the motor relay 20 exceeds the overheat protection temperature of the motor relay 20, the temperature monitoring unit 42 issues a restriction command to the restriction circuit 41. Therefore, the limiting circuit 41, is the steering assist current command value I _M which is calculated according to the steering torque T and the vehicle speed V is restricted, since the energization amount flowing in the motor relay 20 is reduced, the energization of the motor relay 20 Therefore, the overheat protection of the motor relay 20 is achieved.

  When the steering is maintained from this steering state, the electric motor 8 does not rotate in the energized state. Therefore, this is detected in the process of step S4, the process proceeds from step S4 to step S11, and the electric motor 8 rotates. When the state of not being continued for a predetermined time or longer, it is determined that the steering is maintained, the process proceeds from step S11 to step S12, and a correction value preset as a temperature increase correction value of the motor relay 20 is set as the temperature increase correction value ΔTPε. ε1 is set (step S12), and this is added to the average value Wm of the square integrated value (step S6), and a filtering process is performed on this to calculate the energization temperature rise ΔTPup (step S7).

  Here, the temperature increase rate of the motor relay 20 due to energization differs between when the electric motor 8 is rotating and when it is not rotating, and the temperature increase rate is larger in the steered state. For this reason, when the energized temperature increase in the steered state is calculated using the filter 55 that is set as the parameter for calculating the energized temperature increase during normal steering, an error corresponding to the difference in temperature increase rate is included. become. However, since the temperature rise correction value ΔTPε is added to the mean value Wm of the square integrated value and then the temperature rise ΔTPup is calculated by filtering this in the case of the steering holding state, the temperature rise rate An error corresponding to the difference can be canceled out, and an energization temperature increase ΔTPup corresponding to an actual temperature increase during steering can be calculated.

Then, by adding the energization temperature increase ΔTPup calculated in this way and the measured temperature TPr of the temperature sensor 17 to obtain the estimated temperature TPc, the temperature increase due to energization during normal steering and during steering is maintained. It is possible to obtain the estimated temperature TPc of the motor relay 20 that does not include an error due to the difference in rate.
Further, at this time, when the state where the electric motor 8 does not rotate continues for a predetermined time or longer, it is determined that the steering state is maintained. Thus, it is possible to avoid the control that cancels out the error in a state where no error occurs, and the temperature can be estimated with higher accuracy.

From this state, when an abnormality such as disconnection or short-circuit occurs in the temperature sensor 17, the process proceeds from step S8 to step S15, and the estimated ambient temperature for the motor relay set in advance as the ambient temperature of the motor relay 20 TPrr is set as the ambient temperature TPa, and the sum of the ambient temperature TPa and the energization temperature increase ΔTPup is calculated as the estimated temperature TPc.
Here, the estimated ambient temperature TPrr for the motor relay is set to a value corresponding to the maximum value that can be taken as the ambient temperature of the motor relay 20. Therefore, the estimated ambient temperature TPrr for the motor relay always takes a value equal to or higher than the actual ambient temperature of the motor relay 20, and the motor relay calculated using the estimated ambient temperature TPrr for the motor relay. The estimated temperature TPc of 20 always represents a value equal to or higher than the actual temperature of the motor relay 20.

  When a value lower than the actual temperature of the motor relay 20 is calculated as the estimated temperature TPc, the estimated temperature TPc that is lower than the actual temperature is used to determine whether this is equal to or higher than the overheat protection temperature. When the protection judgment is made, there is a possibility that it may be erroneously determined that the restriction is not necessary because the estimated temperature TPc is lower than the actual value even though the restriction for the overheat protection is necessary. . However, as described above, by setting a value equal to or higher than the actual ambient temperature of the motor relay 20 as the estimated ambient temperature TPrr for the motor relay, the estimated temperature TPc of the motor relay 20 becomes the actual temperature of the motor relay 20. Since the value is equal to or higher than the temperature, the overheat protection can be surely performed by performing the overheat protection determination using the estimated temperature calculated in this way.

  In addition, when an abnormality occurs in the temperature sensor 17, it may be possible to continue the temperature estimation using a value immediately before the abnormality occurs. However, after the ignition switch is turned off in a situation where the abnormality continues, Thereafter, when the ignition switch is turned on, depending on the duration of the ignition switch being turned off, the value immediately before the occurrence of the abnormality stored in the memory or the like and the actual temperature of the measurement target of the temperature sensor 17 are calculated. The error becomes large and in some cases the estimated temperature falls below the actual temperature. In this case as well, as described above, although overheat protection is actually required, it is erroneously determined that overheat protection is unnecessary. There is a possibility that.

  Further, for example, when an abnormality that causes the temperature sensor 17 to output a value within a temperature range that can be originally taken as the measured value occurs, the abnormality cannot be detected from the measured temperature of the temperature sensor 17. Therefore, it is difficult to determine which time value is used as the value immediately before the failure, and there is a possibility that the measured temperature at the time when the abnormality occurs is used as the value immediately before the abnormality occurs. At this time, if a value lower than the actual temperature is used as the value immediately before the occurrence of an abnormality, the overheat protection judgment may not be accurately performed in this case as well.

  However, as described above, in the present embodiment, since the maximum value that can be taken as the ambient temperature is used as the estimated ambient temperature for the motor relay 20, the estimated temperature estimated using this estimated ambient temperature. It is possible to avoid that TPc is equal to or lower than the actual ambient temperature, and it is possible to reliably avoid erroneously determining that overheat protection is unnecessary in a situation where overheat protection is required. At this time, since a preset constant is used as the estimated ambient temperature, when an abnormality occurs in the temperature sensor 17, it is only necessary to use the estimated ambient temperature instead of the measured temperature. Since a process such as a new calculation is not required, an alternative ambient temperature can be set quickly, and an abnormality of the temperature sensor 17 can be quickly dealt with.

  Moreover, in the method of performing temperature estimation from the sum of the temperature rise estimated from the motor current detection value supplied to the electric motor 8 and the ambient temperature, which is normally used, the electric motor 8 is in a rotating state. It is possible to obtain an estimated temperature TPc that does not include an error caused by whether or not the electric motor 8 is rotating by simply adding the temperature rise correction value ΔTPε corresponding to whether or not the electric motor 8 is rotating. This can be easily realized without significant change in processing in the unit 10 and increase in load.

  Further, as the temperature increase correction value ΔTPε and the ambient temperature TPa, values set for each temperature estimation target component, that is, values set for the motor relay 20 in the above-described case, are used. When the temperature estimation is performed, various parameters of the filter unit 55 are changed to values corresponding to the temperature estimation target component, and the temperature rise correction value and the value used as the ambient temperature are set as the temperature estimation target component. This can be dealt with only by using the corresponding value. That is, for example, the energization temperature rise ΔTPup considering the operating state of the electric motor 8 can also be estimated by switching the parameter of the filter unit 55 for normal steering and for holding. However, when there are a large number of parameters of the filter unit 55 that should be adjusted according to the operating state of the electric motor 8, it takes time to adjust the parameters for normal steering and for holding and temperature estimation. When the target component is changed, it is necessary to set two parameters each time, which is troublesome.

  However, in the first embodiment, the error due to the difference in temperature increase rate due to the operating state of the electric motor 8 is handled by adding the temperature increase correction value ΔTPε. Therefore, the setting of the parameter of the filter unit 55 may be one-way, even when the temperature estimation target component is changed. It is only necessary to change the increase correction value ΔTPε and the estimation ambient temperature. Therefore, even when the temperature estimation target components are different, it is possible to easily cope with the processing without a significant change in the processing and an increase in load.

  In the first embodiment, a correction value for removing an error due to a difference in temperature increase rate due to the operating state of the electric motor 8 is added to the output of the square settlement average unit 52, and this correction is performed. Since the filter processing is performed by the filter 55 on the average value of the square integration, the square integration average unit 52 can be made common regardless of the temperature estimation target component. Therefore, even if the temperature estimation target component is changed, it is not necessary to change the parameter or the like for the square integration averaging unit 52. Therefore, when the temperature estimation target component is changed, the countermeasure is promptly performed. be able to.

In addition to the motor relay 20, the temperature estimation target components include a motor coil, a fitting portion of a connector terminal of the electric motor 8, and a field effect transistor that constitutes a motor drive circuit 9 for the electric motor 8. All components in the energization path of the motor drive current, such as a switching element such as an FET, can be applied.
In the first embodiment, various parameters of the filter 55 are set on the basis of normal steering, and the correction value ε1 of the motor relay 20 is added as a temperature rise correction value at the time of steering. However, conversely, various parameters of the filter 55 may be set on the basis of the time of steering, and the temperature increase correction value may be subtracted during normal steering.

A functional block diagram of the temperature estimation unit 43 in this case is as shown in FIG.
That is, the average value Wm of the square integrated value of the maximum current value i calculated by the square integrated average unit 52 is input to the subtractor 53 ′. In addition, the temperature rise correction value setting unit 54 ′ sets zero as the temperature rise correction value ΔTPε in the steered state, and in the normal steering state, the temperature rise due to energization during normal steering and in the steered state A correction value ε2 for the motor relay 20 corresponding to the difference in rate is set.

Then, the subtractor 53 ′ subtracts the temperature rise correction value ΔTPε from the average value Wm of the square integrated value of the maximum current value i, and the output of the subtractor 53 ′ is used for calculating the energization temperature rise ΔTPup in the steered state. The parameter 55 is input to the filter 55 ', and the energization temperature rise ΔTPup is calculated.
The output of the filter 55 'and the output of the peripheral temperature setting unit 56 are added by the adder 57, and this is output as the estimated temperature TPc.

  That is, the rate of temperature increase due to energization is higher in the steered state than in normal steering, so the energization during energization operation using the filter 55 'for energization temperature rise calculation in the steered state is performed. When the temperature rise is calculated, the value is calculated higher than the actual value. Therefore, by subtracting the temperature increase correction value ΔTPε by the subtractor 53 ′ by the amount calculated to be higher, an error due to the difference in temperature increase rate due to energization is removed. Therefore, in this case as well, the same effect as above can be obtained.

In the first embodiment, the case has been described in which the maximum current value i is obtained from the three-phase phase currents, and the temperature of the motor relay 20 is estimated using the maximum current value i. The maximum value may be used as the estimated temperature of the final motor relay 20 after performing temperature estimation using each phase current.
In the first embodiment, the case where the energization temperature increase ΔTPup is calculated using a filter including two first-order lag elements has been described. However, the present invention is not limited to this, and the energization temperature increase ΔTPup is calculated. Any filter that can be used can be applied.

Na us, in the first embodiment, the motor current detecting circuit 16 corresponds to the phase current detection unit, a temperature sensor 17 corresponds to the ambient temperature measuring means, corresponding to the temperature estimating section temperature estimation process of FIG. 4 4 corresponds to the motor operating state detection means, the processing in steps S12 and S6 in FIG. 4 corresponds to the correction means, and the processing in step S8 in FIG. 4 corresponds to the monitoring means. Yes.
Further, the limiting circuit 41 and the temperature monitoring unit 42 in FIG. 2 correspond to the overheat protection means.

Next, a second embodiment of the present invention will be described.
Since the second embodiment is the same as the first embodiment except that the configuration of the temperature estimation unit 43 is different, the same parts are denoted by the same reference numerals, and detailed description thereof is omitted. .
FIG. 6 is a functional block diagram of the temperature estimation unit 43 in the second embodiment.
As shown in FIG. 6, the temperature estimation unit 43 in the second embodiment includes a normal steering temperature estimation unit 61 that estimates the temperature of the motor relay 20 when normal steering is performed, and normal steering is performed. Steering state detection unit 62 that determines whether the state is maintained or the state in which the steering is performed, the steering temperature estimation unit 63 that estimates the temperature of the motor relay 20 when the steering is performed, and the normal steering are performed. Sometimes the normal steering temperature Tn estimated by the normal steering temperature estimation unit 61 is the estimated temperature TPc, and when the steering is performed, the estimated temperature using the steering temperature Tk estimated by the steering temperature estimation unit 63 as the estimated temperature TPc. A setting unit 64.

  The normal steering temperature estimator 61 may have any configuration as long as it estimates the temperature of the motor relay 20 when normal steering is performed. For example, the normal steering temperature estimator 61 may be configured to estimate the temperature of the first embodiment. The configuration of the unit 43 has a configuration in which the temperature rise correction value ΔTPε set by the temperature rise correction value setting unit 54 is fixed to “0”. In addition, the normal steering temperature estimation unit 61 calculates the normal steering temperature Tn at a preset period independent of the calculation period of the steering keeping temperature Tk.

  The steering state detection unit 62 estimates the steering state from the operating state of the electric motor 8 and is in a normal steering state where the electric motor 8 rotates and a steering assist force is applied, or in the energized state, the electric motor 8 It is determined whether the steering state is a non-rotating state. For example, when the rotational speed of the electric motor 8 is equal to or lower than a preset threshold value and the electric motor 8 can be regarded as stopped, the holding state is maintained. Judged to be in the rudder state. Note that the rotational speed of the electric motor 8 may be determined based on the motor rotational angular speed obtained by differentiating the motor rotational angle θ from the motor rotational angle sensor 8a, as in the first embodiment.

  The maintained temperature estimation unit 63 detects a phase fixed current detection unit 63a that detects a phase fixed current if that is a phase current to the phase in which the energized phase is fixed in the state of steering, and a phase fixed current detection unit 63a. In accordance with the phase-fixed current if, the steering addition value setting unit that sets the steering addition value ΔTk and the update period H (if) of the steering addition value ΔTk, which is the temperature rise caused by the steering holding state. 63b and the update period H (if) set by the steering holding value setting unit 63b, the steering holding value ΔTk is added to the normal steering temperature Tn estimated by the normal steering temperature estimation unit 61 to calculate the steering temperature Tk. And an adding unit 63c.

The phase-fixed current detection unit 63a detects the maximum value of the three-phase motor current detection values ia, ib, ic as the phase-fixed current if. That is, when normal steering is performed, the energization patterns are sequentially switched in the order of the A-phase, B-phase, C-phase, A-phase, B-phase, C-phase, etc., for the three-phase AC motor. . However, since the motor is not rotated when the steering is maintained, for example, the current is fixed to an energization pattern in which current flows from the A phase to the B phase and the C phase, and a relatively large current flows to the A phase. become. Therefore, the current flowing through the fixed phase, that is, the current value having the largest flowing current value is detected as the phase fixed current if.
In addition, the steering addition value setting unit 63b sets the steering addition value ΔTk and the update period H corresponding to the phase fixed current if based on a preset table.

For example, as shown in FIGS. 7A and 7B, this table is set so that the steerable addition value ΔTk increases as the phase fixed current if increases. That is, since the temperature increase rate of the motor relay 20 increases as the phase fixed current if increases and the amount of flowing current increases, the steering addition value ΔTk is set to increase as the temperature increase rate increases. Further, since the temperature increase rate is small when the phase fixed current if is small, an error from the actual temperature is small even if the temperature increase due to the steering is not frequently reflected in the normal steering temperature Tn, but the phase fixed current if is When it is large, the temperature increase rate is large, and if the temperature increase rate due to the steering is not frequently reflected in the normal steering temperature Tn, the error increases. Therefore, the larger the phase fixed current if, the shorter the update cycle H is set. The higher the error between the normal steering temperature Tn and the actual temperature, the more frequently the temperature increase due to the steering is reflected in the normal steering temperature Tn, and the steering temperature Tk is updated in a shorter cycle. The error between Tk and the actual temperature is made small. Therefore, the steered temperature Tk is updated with a shorter period as the phase fixed current if is larger, and when the temperature change is larger, the updated period is shortened to accurately calculate the steered temperature Tk according to the temperature change, and When the temperature change is small, the update cycle is lengthened to avoid unnecessary calculations.
In FIG. 7A, the phase-fixed current if is I1 <I2 <... <Imax, the steering addition value ΔTk is A <B <... <MAX, and the update period H (if) is H (I1). > H (I2)>...> H (Imax). In FIG. 7B, the horizontal axis represents the phase fixed current if, and the vertical axis represents the steering addition value ΔTk.

Next, the operation of the second embodiment will be described with reference to the flowchart of FIG. 8, which shows an example of the processing procedure of the temperature estimation process in the second embodiment that is executed by the control unit 10.
The control unit 10 drives and controls the electric motor 8 to generate an optimum steering assist force, estimates the temperature of the motor relay 20, and drives and controls the electric motor 8 in consideration of the estimated temperature TPc estimated.

  Then, the normal steering temperature estimation unit 61 of the temperature estimation unit 43 estimates the normal steering temperature Tn at a preset period. Then, the temperature estimation process is executed in a cycle independent of the estimation cycle of the normal steering temperature Tn. First, it is determined whether the electric motor 8 is in the normal steering state or the steering holding state, and the electric motor 8 is energized. When the electric motor 8 is rotating as a result, it is determined that the steering state is normal, and the routine proceeds to step S22, where the normal steering temperature Tn estimated by the normal steering temperature estimation process and stored in the predetermined storage area is read. This is set as the estimated temperature TPc. Then, a preset Hn is set as the update period H of the estimated temperature TPc (step S23), and when the update period Hn has passed (step S24), the process returns to step S21 while normal steering is performed. The processes from step S21 to step S24 are repeated. For this reason, the normal steering temperature Tn is updated and set as the estimated temperature TPc every update cycle Hn, and the temperature change of the motor relay 20 accompanying the energization of the electric motor 8 at the time of normal steering is updated every update cycle Hn. Will be estimated.

  When the steering is carried out from the normal steering state, it is determined that the steering state is maintained because the electric motor 8 is not energized, but the electric motor 8 does not rotate. The current having the maximum current value is specified as the phase fixed current if, and the steering addition value ΔTk (if) and the update period H (if) corresponding to the phase fixed current if are specified from the table (step S32). ). Then, the normal steering temperature Tn estimated in the normal steering temperature estimation process and stored in the predetermined storage area is read, and the steering addition value ΔTk (if) is added to the normal steering temperature Tn, and this is calculated as the estimated temperature TPc. To do. Then, the update cycle H (if) corresponding to the phase fixed current if is set as the update cycle H (step S34), and when the update cycle H (if) has passed (step S24), the process returns to step S21 and is maintained. While the rudder is being performed, the processes of step S21, step S31 to step S34, and step S24 are repeated.

For this reason, the sum of the normal steering temperature Tn and the steering addition value ΔTk (if) is set as the estimated temperature TPc for each update period H (if).
Here, in the case of the steering holding state, the estimated temperature TPc can be calculated by simply adding the steering holding value ΔTk (if) corresponding to the phase fixed current if to the normal steering temperature Tn.
When the estimated temperature TPc is calculated based on, for example, the average value of the squared integrated values of the maximum current values in the case of the steering holding state, as in normal steering, the cycle takes into account the rate of temperature increase due to the steering. In the case of calculation, an increase in processing load accompanying temperature estimation is involved, and a certain calculation speed is required.

  However, as described above, in the steered state, the estimated temperature TPc is calculated by adding the steered addition value ΔTk corresponding to the phase-fixed current if to the normal steering temperature Tn calculated in a predetermined cycle. Therefore, it is possible to calculate an accurate estimated temperature TPc with a small error while suppressing an increase in processing load. Also, at this time, the estimated temperature TPc can be obtained simply by specifying the steering addition value ΔTk corresponding to the phase fixed current if and adding it to the normal steering temperature Tn. The processing procedure for calculating Tn can be easily realized without significant change.

  In particular, in the case of the steering-holding state, it is necessary to quickly estimate the temperature because the rate of temperature increase is large and the rate of change in temperature is large compared to during normal steering. Since the estimated temperature TPc is obtained by adding the steering addition value ΔTk that takes into account the temperature rise associated with the steering to the normal steering temperature Tn that does not significantly affect even if the target is long, the normal steering temperature Even if the update period of Tn is long, by shortening the update period of the steering addition value ΔTk, only by adding the steering addition value ΔTk, the estimated temperature TPc with less error in consideration of the temperature rise due to the steering can be obtained. Can be obtained.

  The update period H (if) is set according to the phase fixed current if and is set to be shorter as the phase fixed current if is larger. When the phase fixed current if is large, the temperature increase rate increases, so the temperature increase of the motor relay 20 also increases. However, the steering addition value ΔTk (if) increases as the phase fixed current if increases. Therefore, the steering addition value ΔTk (if) corresponding to the temperature rise corresponding to the phase fixed current if can be calculated in a shorter cycle, and by adding this to the normal steering temperature Tn Thus, a more accurate estimated temperature TPc can be obtained.

  Further, since the rate of temperature increase differs according to the phase fixed current if, the temperature change amount per predetermined time of the estimated temperature TPc increases as the phase fixed current if increases. For this reason, when the estimated temperature TPc is updated at regular intervals, the error between the estimated temperature TPc and the actual temperature increases as the phase fixed current if increases. However, the update period H of the estimated temperature TPc is set according to the phase fixed current if, and the update period H of the estimated temperature TPc becomes shorter as the phase fixed current if is larger. The update period H of the estimated temperature TPc is shortened as the temperature increases, so that the temperature error between the actual temperature and the estimated temperature TPc can be reduced, and the temperature estimation can be performed with higher accuracy.

Further, when the temperature change due to energization is small and the error between the actual temperature and the estimated temperature TPc is small, the update cycle of the estimated temperature TPc is lengthened, so that the processing load can be reduced accordingly.
In addition, since the temperature estimation of the motor relay 20 can be realized without a significant processing load in this way, not only the motor relay 20 but also a motor drive current energization path as a temperature estimation target component. Even when temperature estimation is performed for each of a plurality of components, as described above, the estimated temperature TPc in the steered state is simply obtained by adding the steered addition value ΔTk to the normal steering temperature Tn during normal steering. Since it can detect, it can implement | achieve, without significantly increasing the arithmetic processing load of a processing apparatus in connection with performing temperature estimation in consideration of a steering maintenance state.

  In addition, if one heat protection control performs temperature estimation during normal steering and temperature estimation under phase-fixed conditions such as during steering, and heat protection processing is performed based on these, temperature estimation is In order to perform estimation suitable for the phase fixing condition, in the heat protection control, the heat protection with a margin of about three times that during normal steering is performed. That is, there is a problem that the degree of protection of the heat protection differs depending on the steering mode. However, as described above, highly accurate temperature estimation according to each steering mode can be performed, so that heating protection suitable for each can be performed without overprotection.

In addition, since the temperature of each part can be estimated with high accuracy in this way, the temperature condition of each part can be accurately determined according to the temperature protection conditions of each part. Limiting can be performed, and the steering assist by the electric power steering apparatus can be utilized to the maximum extent possible.
In the second embodiment, the case where the estimated temperature TPc is calculated using the steering addition value ΔTk and the normal steering temperature Tn in the steering holding state has been described. However, the present invention is not limited to this.

  Further, in the second embodiment, the case where the estimated temperature TPc is calculated by adding the steering addition value ΔTk corresponding to the phase fixed current if to the normal steering temperature Tn calculated at a predetermined period will be described. However, although the calculation processing load slightly increases, the normal steering temperature Tn and the steering addition value ΔTk are calculated at the timing of the update period H corresponding to the phase fixed current if, and the estimated temperature TPc is calculated based on these. You may make it do.

  In the second embodiment, the case where the motor relay 20 is used as a temperature estimation target component has been described. However, the present invention is not limited to this, as in the first embodiment. All parts in the current path of the motor drive current, such as the fitting portion of the motor coil and the connector element of the electric motor 8, and the switching element such as the field effect transistor FET constituting the motor drive circuit 9 for the electric motor 8 Can be applied.

  In each of the above embodiments, the case where it is determined that the steering state is maintained when the electric motor 8 is energized and the electric motor 8 is not rotating is described. However, the present invention is not limited to this. When the fluctuation amount of T is small and the fluctuation amount of the rotation speed of the electric motor 8 is small, it may be determined that the steering state is maintained. In short, any method can be used as long as it can be detected that the steering state is maintained. It may be.

In each of the above embodiments, the case where the present invention is applied to a three-phase motor has been described. However, the present invention is not limited to this. For example, a brush motor, a multiphase brushless motor, or the like can be applied.
In the second embodiment, the motor current detection circuit 16 corresponds to the phase current detection means, the normal steering temperature estimation section 61 corresponds to the temperature estimation means, and the steering state detection section 62 corresponds to the motor operation state detection means. The phase fixed current detection unit 63a and the steered addition value estimation unit 63b correspond to the correction value calculation unit, and the addition unit 63c corresponds to the correction unit.

Is a schematic diagram showing an embodiment of the applied electric power steering grayed apparatus of the present invention. It is a functional block diagram which shows the specific structure of the control unit of FIG. It is a functional block diagram which shows the specific structure of the temperature estimation part of 1st Embodiment. It is a flowchart which shows an example of the process sequence of the temperature estimation process in the temperature estimation part of 1st Embodiment. It is a functional block diagram which shows the other example of a temperature estimation part. It is a functional block diagram which shows the specific structure of the temperature estimation part of 2nd Embodiment. It is explanatory drawing showing a response | compatibility with a phase fixed electric current, a steering addition value, and an update period. It is a flowchart which shows an example of the process sequence of the temperature estimation process in the temperature estimation part of 2nd Embodiment.

Explanation of symbols

7 Steering torque sensor 8 Electric motor 10 Control unit 14 Vehicle speed sensor 16 Motor current detection circuit 17 Temperature sensor 41 Limit circuit 42 Temperature monitoring unit 43 Temperature estimation unit

Claims (5)

In an electric power steering apparatus having an electric motor for generating a steering assist force and having a temperature detecting device for detecting the temperature of its constituent parts in the motor system of the electric motor,
The temperature detector is
And the phase current detecting means for detecting a phase current of the electric motor,
Ambient temperature measuring means for measuring the ambient temperature of the temperature detection target component among the electric motor and the components of the motor system arranged in the drive current energization path;
Using the phase current detection value detected by the phase current detection unit, the temperature increase due to energization of the temperature detection target component is estimated, and the temperature measurement measured by the temperature increase and the ambient temperature measurement unit a temperature estimation means from the sum of the value for estimating the temperature of the components of the temperature detection target, and
The ambient temperature measuring means includes monitoring means for monitoring the abnormality,
The temperature estimating means detects, when the monitoring means detects an abnormality in the ambient temperature measuring means, instead of the temperature measurement value of the ambient temperature measuring means, for each of the component parts corresponding to the temperature detection target component parts. An electric power steering apparatus characterized in that the temperature of a component to be detected by temperature is estimated using a preset ambient temperature for estimation. Motor operating state detecting means for detecting whether the electric motor is in a rotating state or a stopped state;
  A correction value for correcting a temperature increase rate difference caused by the operating state of the electric motor preset for each temperature detection target component is added to the calculation value in the calculation process of the temperature increase estimated by the temperature estimation means. The electric power steering apparatus according to claim 1, further comprising a correction unit that corrects the temperature increase by addition or subtraction. The temperature estimating means filters the square integrated average part for calculating an average of square integrated values of the phase current detection values detected by the phase current detecting means, and filters the average value calculated by the square integrated average part A filter unit for estimating the temperature rise,
  3. The electric power steering apparatus according to claim 2, wherein the correction unit corrects the average value calculated by the square integration average unit input to the filter unit. The electric motor according to any one of claims 1 to 3, wherein the estimation ambient temperature is set to a value corresponding to a maximum value that can be taken by an ambient temperature of the temperature detection target component. Power steering device. The correction value calculation means for calculating a correction value for correcting the temperature increase rate difference of the temperature detection target component using the phase current detection value is provided. The electric power steering device according to claim 1.

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