JP5168057B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an electric power steering apparatus, and more particularly to an electric power steering apparatus that can continue steering assist control even if a motor rotation angle detection system such as a resolver fails.

As this type of electric power steering apparatus, for example, a technique described in Patent Document 1 is known. In Patent Document 1, even if a motor rotation angle detection system such as a resolver fails, a relative angle amount of an electric motor and its rotation direction (relative angle integration direction) necessary for continuing steering assist control are described. Is disclosed as a technique for determining the relative angle information.
In the technique described in this document, the relative angular amount of the electric motor is calculated based on each line induced voltage by calculating each line induced voltage from each terminal voltage value and each phase current value of the electric motor. The angular amount is determined. Further, the rotation direction of the electric motor is determined based on the steering torque. As a result, the determined relative angle amount of the electric motor and the rotation direction thereof are used as relative angle information, and this is integrated with the estimated electric angle estimated last time, so that the electric motor can be continuously controlled. Therefore, according to the technique described in the document, even if the motor rotation angle detection system is out of order, the steering assist control can be continued.
JP 2008-87756 A

  However, in the technique described in Patent Document 1, since the steering torque direction is the relative angle integration direction, when the rotation direction of the electric motor is reversed with respect to the steering torque direction (that is, when the steering wheel is turned back). Thus, the actual angle of the electric motor and the estimated electrical angle will deviate. As a result, there is still a problem to be solved in that there is a possibility of causing a handle vibration when the handle is turned back.

  Accordingly, the present invention has been made paying attention to such problems, and in the event that a motor rotation angle detection system such as a resolver fails, the steering assist control can be continued and the steering torque direction An object of the present invention is to provide an electric power steering device that prevents or suppresses the possibility of causing steering vibration even when the rotation direction of the electric motor is reversed, and can further suppress discomfort to the driver. It is said.

The inventors of the present invention determined the relative angle integration direction necessary for detecting the position of the electric motor based on the information on the sign relationship of the back electromotive voltage between the lines of the electric motor, thereby solving the above problem.
First, the calculation principle of the rotation direction (relative angle integration direction) in the present invention will be described.
The relationship between the back electromotive force between lines and the electrical angle of the electric motor is as shown in Table 1 below and FIGS. FIG. 1 is a diagram for explaining the calculation principle of the rotation direction in the present invention. FIG. 1A is a waveform example of each line back electromotive voltage during forward rotation, and FIG. It is an example of a waveform of each line back electromotive voltage at the time of reverse direction rotation. Table 1 shows the sign relationship of the back electromotive force between the lines shown in FIG. 1 when the electric angle of the electric motor is divided into 60 (deg el) angle regions. Further, FIG. 2 is an arrangement diagram of the respective symbol relationships when the contents of Table 1 are expressed in a polar coordinate system, in which the inner circle represents forward rotation and the outer circle in FIG. Represents. The shaded display in the figure corresponds to the same shaded display in Table 1, respectively.

  As can be seen from Table 1 and FIGS. 1 and 2, the sign relationship of the back electromotive force between the lines differs between when the electric motor rotates in the forward direction and when it rotates in the reverse direction. For example, as shown in FIG. 2, the electric angle of the actual electric motor is now located in an angle region of 0 to 60 (deg el), and the rotation direction is reversed (reverse rotation from forward rotation). Assuming that, the positive / negative sign relationship of the back electromotive force between the lines of the electric motor changes from the state α in FIG. 2 to the state β. Therefore, if the rotation direction of the electric motor is found, the region where the actual electric angle of the electric motor is located (absolute angle region) can be estimated.

Here, when attention is paid with reference to the sign relationship of the back electromotive force between the lines when the predetermined direction is the forward rotation, the sign relationship of the state β described above is 180 to 180 in the forward rotation direction as shown in FIG. It is the same as β ′ in the sign relation at 240 (deg el) (see Table 1). This looks like the absolute angle region is inverted 180 degrees (see FIG. 2).
That is, as shown in FIG. 3, the relationship between the absolute angle region Z (hereinafter also referred to as “estimated absolute angle region”) based on the rotation of the electric motor in a predetermined direction and the actual electrical angle (black circle symbol in the figure). If the electric motor rotates in the forward direction when the predetermined direction is the forward direction (see (a) in the figure), the actual electrical angle is within the estimated absolute angle region Z and the reverse direction If it is rotation (see FIG. 5B), it is out of the range of the region Z. FIG. 3 is a diagram for explaining an absolute angle region calculated with reference to a positive direction rotation (counterclockwise direction in the figure) as a predetermined direction. FIG. 3A shows a state in which the electric motor rotates in the positive direction. Moreover, the same figure (b) has shown the time of reverse direction rotation. In the figure, the shaded area represents the estimated absolute angle area Z based on the rotation of the electric motor in a predetermined direction, and the black circle symbol represents the actual electric angle of the electric motor. The indication by the mark symbol represents the estimated electrical angle, and the arrow indicated by symbol R represents the actual rotation direction of the electric motor (the same applies to FIGS. 4 to 7 shown below).

That is, suppose that the estimated electrical angle is a substantially actual electrical angle of the electric motor. When the electric motor actually rotates in the reverse direction from the predetermined direction, the estimated electrical angle is also in the estimated absolute angle region Z. You can see that it is out of range.
Therefore, in the calculation of the rotation direction (relative angle integration direction) in the present invention, in view of the above knowledge, the positional relationship between the estimated absolute angle region and the estimated electrical angle is compared, and the estimated electrical angle is within the estimated absolute angle region. Therefore, the rotation direction of the electric motor is basically estimated by rotating in the forward direction and rotating in the reverse direction if outside the same region.

However, in the above knowledge, if the actual motor electrical angle is located near the switching boundary of the estimated absolute angle region and there is a delay error in the estimated absolute angle, the relative angle integration direction to rotate the electric motor is estimated in reverse. There is a possibility that.
Therefore, in the present invention, a determination angle region in which the determination range of the relative angle integration direction is expanded is set, and thereby, the estimated electrical angle information is compared with the case where only the estimated absolute angle region is compared. Even when there is a delay error, the rotation direction can be determined stably.

  That is, the present invention relates to an electric motor that generates a steering assist force for a steering system, torque detection means that detects a steering torque transmitted to the steering system, and the electric motor according to a steering amount for the steering system. Motor relative angle determination means for determining the relative angle information of the steering torque detected by the torque detection means, the rotational electrical angle detected by the position detector of the electric motor, and the relative determination by the motor relative angle determination means An electric power steering apparatus comprising: a control unit that drives and controls the electric motor in accordance with angle information, wherein the motor relative angle determination unit includes relative angle information of the electric motor in accordance with a steering amount with respect to the steering system. Motor relative angle information calculation unit for calculating the relative angle information and electrical rotation angle information cannot be obtained from the motor relative angle information calculation unit. However, based on the information on the back electromotive force between each line of the electric motor and its sign relationship, the relative angular amount necessary for detecting the position of the electric motor and the relative angle integration direction to be rotated can be substituted. An alternative relative angle information calculation unit that generates as angle information and obtains a relative estimated electrical angle from the alternative relative angle information, wherein the alternative relative angle information calculation unit has a sign relationship of each line back electromotive voltage of the electric motor The absolute angle region is calculated based on the estimated absolute angle region obtained by dividing the electrical angle every 60 ° with reference to the time when the electric motor rotates in a predetermined direction, and the intermediate angle of the calculated estimated absolute angle region is output. Based on the region setting means, the previously calculated estimated electrical angle and the previously calculated relative angle information, a temporary estimated electrical angle corresponding to the current estimated electrical angle is calculated as estimated electrical angle information, and the estimated Comparing the constant electrical angle information and the determination angle region that is a range of ± 90 ° of the intermediate angle of the estimated absolute angle region, if the estimated electrical angle information is within the range of the determination angle region, The predetermined direction is a relative angle integration direction, and if it is out of the range of the determination angle area, there is provided an area determination means for setting a direction opposite to the predetermined direction as a relative angle integration direction.

  According to the electric power steering apparatus of the present invention, the motor relative angle determination unit generates the relative angle amount necessary for detecting the position of the electric motor and the relative angle integration direction to be rotated as alternative relative angle information. The relative relative angle information calculation unit includes a relative angular amount necessary for detecting the position of the electric motor based on information on the back electromotive force between the lines of the electric motor and the sign relationship thereof. And the relative angle integration direction to be rotated is determined, so that even if the motor rotation angle detection system such as the resolver fails, the relative angle integration direction can be estimated and only based on the steering torque. Compared with the case where the relative angle integration direction is determined, the possibility of causing steering wheel vibration is prevented or suppressed even when the rotation direction of the electric motor is reversed with respect to the steering torque direction. Door can be. Therefore, it is possible to further suppress the driver from feeling uncomfortable.

  Further, in the electric power steering apparatus according to the present invention, the alternative relative angle information calculation unit includes an absolute angle region setting unit and a region determination unit, and the absolute angle region setting unit is configured to connect each line of the electric motor. Based on the sign relationship of the counter electromotive voltage, an estimated absolute angle region in which the electrical angle is divided every 60 ° with reference to the time when the electric motor rotates in a predetermined direction is calculated, and an intermediate between the calculated estimated absolute angle regions The angle is output, and the region determination unit calculates a temporary estimated electrical angle corresponding to the current estimated electrical angle based on the previously calculated estimated electrical angle and the previously calculated relative angle information as estimated electrical angle information, and performs the estimation. The electrical angle information is compared with a determination angle region that is a range of ± 90 ° of an intermediate angle of the estimated absolute angle region, and the estimated electrical angle information is a range of the determination angle region. If so, the predetermined direction is set as the relative angle integration direction, and if it is outside the range of the determination angle area, the reverse direction of the predetermined direction is set as the relative angle integration direction. Compared to the case where the estimated electrical angle information has a delay error, the rotational direction can be determined stably.

  For example, as shown in FIG. 4, the determination angle range W that is expanded to a range of ± 90 ° of the intermediate angle is compared with the estimated electrical angle, and if it is within the range of the determination angle range W It is determined that the rotation is in a predetermined direction (for example, normal direction rotation). As a result, the relative angular integration direction determination range is expanded, so that the rotational direction can be stabilized even when there is a delay error in the estimated electrical angle information, compared to the case where only the estimated absolute angle region is compared. Can be determined. In FIG. 4, a broken-line arrow with a symbol H indicates a relative angular direction obtained by region determination according to the present invention.

  In the electric power steering apparatus according to the present invention, for example, when the calculation speed of a microcomputer or the like is sufficiently high, the area determination unit estimates the estimated electric angle calculated last time instead of the temporary estimated electric angle. It can be used as electrical angle information. With such a configuration, there is no need to perform the temporary estimated electrical angle calculation, and thus there is an effect of reducing the calculation load accordingly.

Here, if noise is mixed in the calculated value of the back electromotive force voltage between lines, the sign relationship of the back electromotive force voltage between the lines is easily switched near the switching boundary line of the absolute angle region, so that the region determination to the adjacent region is performed. There is a concern that hunting is likely to occur.
Therefore, in the electric power steering apparatus according to the present invention, for example, when the intermediate angle calculated by the absolute angle region setting unit is changed, the alternative relative angle information calculation unit is based on the change amount and the transition direction. And an intermediate angle shift calculation means for outputting a new post-shift intermediate angle obtained by shifting the intermediate angle, wherein the region determination means is ± 90 ° of the post-shift intermediate angle output from the intermediate angle shift calculation means. Is determined as an angle region for determination, the angle region for determination is compared with the estimated electrical angle information, and if the estimated electrical angle information is within the range of the angle region for determination, the predetermined direction is relative. If the angle integration direction is outside the range of the angle region for determination, it is more preferable that the reverse direction of the predetermined direction is the relative angle integration direction.

  With such a configuration, the transition direction when the intermediate angle shifts is determined, a new post-shift intermediate angle obtained by shifting the intermediate angle according to the determined transition direction is calculated, and the intermediate angle after the shift is calculated. Since the determination angle region is generated by using, as shown in FIGS. 5 to 7, for example, the determination angle region does not move even if there is hunting when determining the region to the adjacent region. It is more suitable for enhancing resistance.

  Here, as an example of determining the transition direction when the intermediate angle shifts, and calculating a new post-shift intermediate angle obtained by shifting the intermediate angle according to the determined transition direction, for example, to an adjacent region in the positive direction 5, for example, a value obtained by shifting the intermediate angle θc by −30 (deg el), for example, to −30 (deg el) is set as the post-shift intermediate angle θc sht, and the ± The range of 90 ° is set as the determination angle region W. Further, for example, in the case of a transition to a region adjacent in the reverse direction, as illustrated in FIG. 6, a value obtained by, for example, +30 (deg el) is set to the intermediate angle θc sht after the shift. A range of ± 90 ° with respect to the angle θc sht is set as a determination angle region W. Furthermore, in the case of a transition other than those shown in FIGS. 5 to 6, as shown in FIG. 7, for example, the range of ± 90 ° of the previous intermediate angle θc is determined without shifting the intermediate angle θc. An angle region W is used. Further, when there is no transition of the intermediate angle θc, for example, a configuration in which the range of ± 90 ° of the intermediate angle θc sht after the previous shift is set as the determination angle region W without performing a shift can be exemplified.

Further, as another concern, when the electric motor is at a low speed, the back electromotive force between the lines is small, and therefore there is a possibility that the determination of the absolute angle region is erroneously determined due to the influence of noise.
Therefore, in the electric power steering apparatus according to the present invention, for example, the alternative relative angle information calculation unit is configured so that the region determination unit determines whether the maximum value of each line back electromotive voltage value of the electric motor does not exceed a predetermined threshold. When the determination dead zone has a maximum value of each line back electromotive voltage value, the steering torque direction is determined based on the steering torque detected by the steering torque detection means. It is preferable to further include a final rotation direction determination unit that sets the relative angle integration direction and uses the determination result by the region determination unit as a relative angle integration direction when there is no maximum value of each line back electromotive voltage value in the determination dead zone. .

  That is, with such a configuration, when the electric motor is running at a low speed, the steering torque detected by the steering torque detecting means is low when the back electromotive force between the lines is small and the reliability of the acquired value of the sign relationship is low. Therefore, the steering torque direction can be set to the relative angle integration direction, which is more preferable in preventing or suppressing the possibility of making an erroneous determination in the determination of the absolute angle region due to the influence of noise.

  Furthermore, in the electric power steering apparatus according to the present invention, for example, the alternative relative angle information calculation unit determines the region unless the second largest value of the back electromotive voltage value between the lines of the electric motor exceeds a predetermined threshold value. If the determination dead zone has a second largest value of each line back electromotive voltage value, the steering torque detected by the steering torque detection means is included. Based on the steering torque direction as the relative angle integration direction, and when there is no second largest value of each line back electromotive voltage value in the determination dead zone, the final rotation with the determination result by the region determination means as the relative angle integration direction It is also preferable to further include a direction determination means.

  Even in such a configuration, when the electric motor is running at a low speed, the steering torque detected by the steering torque detecting means when the back electromotive force between the lines is small and the reliability of the acquired value of the sign relationship is low. Therefore, the steering torque direction can be set to the relative angle integration direction, which is more preferable in preventing or suppressing the possibility of making an erroneous determination in the determination of the absolute angle region due to the influence of noise.

Furthermore, as another concern, when noise or the like is mixed in the back electromotive voltage value, the error may be accumulated and the estimated electrical angle error may increase. Here, when the estimated absolute angle region divided every 60 ° shifts to the adjacent region, the electrical angle of the electric motor to be estimated exists on the region boundary angle.
Therefore, in the electric power steering apparatus according to the present invention, for example, the alternative relative angle information calculation unit, when the estimated absolute angle region shifts to an adjacent region, the estimated absolute angle region before the transition and the estimated absolute angle after the transition. It is preferable that the boundary angle with the angle region is a corrected estimated electrical angle, and the estimated electrical angle is corrected to the corrected estimated electrical angle. With such a configuration, it is possible to prevent an increase in the estimated electrical angle error by correcting the estimated electrical angle.

However, since the estimated absolute angle region is defined by the angle region with the predetermined rotation direction as a reference, when the region is moved in the direction opposite to the predetermined rotation direction, the boundary angle is relative to the motor electrical angle to be estimated. 180 ° opposite position.
Therefore, for example, the alternative relative angle information calculation unit is configured so that the transition direction when the estimated absolute angle region transitions to an adjacent region is the same as the predetermined rotation direction used as a reference when calculating the estimated absolute angle region. In some cases, it is more preferable that the boundary angle is a corrected estimated electrical angle, and if the boundary angle is a different direction, the boundary angle + 180 ° is a corrected estimated electrical angle. Such a configuration is suitable for more accurately calculating the corrected estimated electrical angle.

Furthermore, in the vicinity of the switching angle of the absolute angle region, the sign relationship of the back electromotive force between the lines is easily switched, and there is a possibility that absolute angle region determination causes hunting between adjacent regions. In this case, since the region transition direction is also hunted, the corrected estimated electrical angle may be wrong.
Therefore, for example, the alternative relative angle information calculation unit may further set the timing for correcting the estimated electrical angle when the post-shift intermediate angle changes and the estimated absolute angle region shifts to an adjacent region. preferable. With such a configuration, the post-shift intermediate angle does not move during the hunting, so that the estimated electrical angle can be corrected more accurately by adding it as a correction timing condition.

  As described above, according to the electric power steering apparatus of the present invention, even if the motor rotation angle detection system such as the resolver fails, the steering assist control can be continued and the steering torque direction can be controlled. Thus, even when the rotation direction of the electric motor is reversed, the possibility of causing handle vibration can be prevented or suppressed. Therefore, it is possible to further suppress the driver from feeling uncomfortable.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate.
FIG. 8 is an overall configuration diagram showing an embodiment of the present invention. In the figure, reference numeral 1 denotes a battery mounted on a normal vehicle, and a battery voltage Vb output from the battery 1 is a fuse. 2 to the control device 3. This control device 3 is a motor drive that drives an electric motor 5 that generates a steering assist force for a steering system in which a battery voltage Vb input via a fuse 2 is input via a relay 4 shown in FIG. A motor drive circuit 6 is provided as means.

  The electric motor 5 is composed of, for example, a star (Y) -connected brushless motor driven by three-phase alternating current, and operates as a steering assist force generation motor that generates a steering assist force of the electric power steering apparatus. The electric motor 5 is coupled to a steering shaft 12 to which a steering wheel 11 is connected via a speed reduction mechanism 13, the steering shaft 12 is coupled to a rack and pinion mechanism 14, and the rack and pinion mechanism 14 is coupled to a coupling mechanism such as a tie rod. 15 is connected to the left and right steered wheels 16.

The steering shaft 12 is provided with a steering torque sensor 17 for detecting the steering torque input to the steering wheel 11, and the electric motor 5 is provided with a resolver 18 for detecting a motor rotation angle. The steering torque detection signal detected at 17 and the motor rotation angle detection signal detected by the resolver 18 are input to the control device 3.
The steering torque sensor 17 is a torque detection means for detecting a steering torque applied to the steering wheel 11 and transmitted to the steering shaft 12, and for example, a torsion in which the steering torque is interposed between an input shaft and an output shaft (not shown). The bar is converted into a torsional angular displacement, and this torsional angular displacement is detected by a magnetic signal and converted into an electrical signal.

As shown in FIG. 9, the steering torque sensor 17 has a predetermined neutral steering torque detection value T ₀ when the input steering torque is zero. The steering torque detection value T is a value that increases from the neutral steering torque detection value T ₀ , and when the steering torque is turned to the left from the zero state, the steering torque detection value T that decreases from the neutral steering torque T ₀ according to the increase of the steering torque is output. ing.

  As shown in FIG. 10, the motor driving circuit 6 includes a series circuit in which two field effect transistors Qaa and Qab are connected in series, and two field effect transistors Qba and Qbb connected in parallel with the series circuit. And an inverter circuit 21 including a series circuit of field effect transistors Qca and Qcb. In the inverter circuit 21, the connection points of the field effect transistors Qaa and Qab, the connection points of the field effect transistors Qba and Qbb, and the connection points of the field effect transistors Qca and Qcb are connected to the respective excitation coils La, Lb connected to the electric motor 5 in a star connection. Motor drive currents Ia and Ib connected to Lc and output from the inverter circuit 21 to the electric motor 5 are detected by the motor current detection circuit 7.

  The motor drive circuit 6 also has an FET gate drive circuit 22 that controls each field effect transistor of the inverter circuit 21. This FET gate drive circuit 22 controls the field effect transistor of the inverter circuit 21 by PWM (with a duty ratio Da, Db and Dc determined based on current command values Iat, Ibt and Ict outputted from a microcomputer 30 which will be described later. It is turned on / off by a (pulse width modulation) signal, and the magnitudes of currents Ia, Ib and Ic that actually flow through the electric motor 5 are controlled.

  Further, the control device 3 includes a microcomputer 30 that supplies a pulse width modulation signal having a duty ratio for generating a steering assist force by the electric motor 5 to the gate drive circuit 22. The microcomputer 30 is supplied with a stabilized power supply as a control power supply that is output from a stabilized power supply circuit 34 that is connected to the fuse 2 and forms, for example, a 5 V microcomputer power supply.

  The microcomputer 30 has terminals for detecting the phase current detection values Ia to Ic input from the current detection circuit 7 for detecting the phase currents of the electric motor 5 and the terminal voltages of the phases of the electric motor 5. The phase terminal voltages Va to Vc input from the voltage detection circuit 8 are input, and the steering torque signal Ts detected by the steering torque sensor 17 is input via the A / D conversion circuit 31, and the output of the resolver 18. The motor rotation angle signals sin θ and cos θ from the motor rotation angle detection circuit 32 that outputs the motor rotation angle signal to which the signal is input are input to the input terminal, and further the vehicle speed detection value output from the vehicle speed sensor 33 that detects the vehicle speed Vs. Vs is input.

  Here, the motor rotation angle detection circuit 32 supplies a carrier wave signal sin ωt having a predetermined frequency to the resolver 18, and a sine wave signal (sin ωt · sin θ) having a waveform obtained by amplitude-modulating the carrier wave signal sin ωt with a sine wave sin θ. And a cosine wave signal (sin ωt · cos θ) having a waveform obtained by amplitude-modulating the carrier signal sin ωt with a cosine wave cos θ, and A / D conversion of the sine wave signal (sin ωt · sin θ) and the cosine wave signal (sin ωt · cos θ). For example, a positive peak timing of the carrier wave sin ωt is detected and a peak detection pulse Pp is input to the microcomputer 30 through the devices 35 and 36.

The configuration of the microcomputer 30 is represented by a functional block diagram as shown in FIG. 11, and the steering torque T input from the steering torque sensor 17 by a fail-safe signal SF from a fail-safe processing unit 49 described later is abrupt. The gradual change control unit 41 that suppresses the change and gradually changes, the steering torque Ts whose rapid change is limited by the gradual change control unit 41, and the vehicle speed Vs detected by the vehicle speed sensor 33 are input and will be described later. A current command value calculation unit 42 that calculates the three-phase current command values Ia ^{* to} Ic ^* by performing vector control based on the motor rotation angle θe, the angular velocity ωe, and the angular acceleration α input from the angular velocity / angular acceleration calculation unit 48. And current command values Ia ^{* to} Ic ^* output from the current command value calculation unit 42 as fail-safe signals from a fail-safe processing unit 49 described later. Current output limiting unit 43 limited by SF, current command values Ia ^{* to} Ic ^* output from current output limiting unit 43 and phase current detection values Ia to Ic input from current detection circuit 7 are subtracted to obtain a deviation. Subtraction unit 44 for calculating ΔIa to ΔIc, and deviations ΔIa to ΔIc output from this subtraction unit 44 are, for example, proportionally / integrated (PI) controlled so that command voltages Va ^{* to} Vc ^* are driven by the FET gate of motor drive circuit 6. Based on these, current control unit 45 output to circuit 22, current detection values Ia to Ic input from current detection circuit 7, and terminal voltages Va to Vc input from terminal voltage detection circuit 8 are input. A counter electromotive voltage calculation unit 46 that calculates line counter electromotive voltages EMFab, EMFbc, and EMFCa generated between the lines of each motor coil, and a sine wave signal (from the motor rotation angle detection circuit 32) inωt · sin θ), a cosine wave signal (sin ωt · cos θ), and a peak detection pulse Pp, a motor rotation angle calculation unit 47 for calculating a motor rotation angle θer expressed in electrical angle, and a counter electromotive voltage calculation unit 46 An angular velocity / angular acceleration calculation unit 48 that calculates an angular velocity and an angular acceleration based on the calculated line back electromotive voltages EMFab, EMFbc, EMFCa and the motor rotation angle θer calculated by the motor rotation angle calculation unit 47, and a steering torque The steering torque Ts detected by the sensor 17, the vehicle speed detection value Vs detected by the vehicle speed sensor 6, and the motor rotation angle θer calculated by the motor rotation angle calculation unit 47 are input. Based on these, the steering torque sensor 17 and the vehicle speed sensor 33 are input. In addition, failure of the resolver 18, the motor rotation angle detection circuit 32, and the motor rotation angle calculation unit 47 is detected, and fail-safe processing is performed. And a fail-safe processing unit 49 as a motor rotation angle abnormality detecting means.

As shown in FIG. 12, the current command value calculation unit 42 includes a steering assist torque command value calculation unit 42A that calculates a steering assist current command value I _M ^*, and a steering assist calculated by the steering assist torque command value calculation unit 42A. A command value compensation unit 42B that compensates the current command value I _M ^* based on an angular velocity ωe and an angular acceleration α input from an angular velocity / angular acceleration calculation unit 48 described in detail later, and the command value compensation unit 42B A dq-axis current command value calculation unit 42C that calculates a dq-axis current command value based on the compensated post-compensation torque command value I _M ^* 'and converts it into a three-phase current command value.

The steering assist torque command value calculation unit 42A calculates a steering assist torque command value I _M ^* which is a current command value with reference to the steering assist torque command value calculation map shown in FIG. 13 based on the steering torque Ts and the vehicle speed Vs. To do. This steering assist torque command value calculation map has a parabolic shape with the steering torque Ts on the horizontal axis, the steering assist torque command value I _M ^* on the vertical axis, and the vehicle speed Vs as a parameter, as shown in FIG. It is composed of a characteristic diagram represented by a curve, and the steering assist torque command value I _M ^* is maintained at “0” while the steering torque Ts is between “0” and a set value Ts1 in the vicinity thereof, and the steering torque T is When the set value Ts1 is exceeded, initially, the steering assist command value I _M ^* increases relatively gently with respect to the increase in the steering torque T, but when the steering torque T further increases, the steering assist torque command value with respect to the increase. I _M ^* is set so as to increase steeply, and this characteristic curve is set so that the inclination becomes smaller as the vehicle speed increases.

  The command value compensator 42B is calculated by the convergence compensator 51 for compensating the convergence of the yaw rate based on the motor angular velocity ωe calculated by the angular velocity / angular acceleration calculator 48 described later, and the angular velocity / angular acceleration calculator 48. Based on the motor angular acceleration α, the inertia compensator 52 that compensates for the torque equivalent generated by the inertia of the electric motor 5 to prevent deterioration of the feeling of inertia or control responsiveness, and the self-aligning torque (SAT) are estimated. And a SAT estimation feedback unit 53.

  The convergence compensator 51 receives the vehicle speed Vs detected by the vehicle speed sensor 33 and the motor angular velocity ωe calculated by the angular velocity / angular acceleration calculator 48, and the steering wheel 1 shakes to improve the yaw convergence of the vehicle. The convergence compensation value Ic is calculated by multiplying the motor angular velocity ωe by the convergence control gain Kv that is changed according to the vehicle speed V so that the brake is applied to the turning operation.

The SAT estimation feedback unit 53 receives the steering torque T, the angular velocity ω, the angular acceleration α, and the steering assist current command value I _M ^* calculated by the steering assist torque command value calculation unit 42A. The torque SAT is estimated and calculated. The principle of calculating the self-aligning torque SAT will be described with reference to FIG. 14 showing the state of torque generated between the road surface and the steering.

That is, when the driver steers the steering wheel 1, a steering torque T is generated, and the electric motor 5 generates an assist torque Tm according to the steering torque T. As a result, the wheel W is steered and a self-aligning torque SAT is generated as a reaction force.
Further, at that time, torque serving as a steering resistance of the steering wheel 1 is generated by the inertia J and friction (static friction) Fr of the electric motor 5. Considering the balance of these forces, the following equation of motion can be obtained:
J · α + Fr · sign (ω) + SAT = Tm + T (1)

Here, when the above equation (1) is Laplace transformed with the initial value zero and the self-aligning torque SAT is solved, the following equation (2) is obtained.
SAT (s) = Tm (s) + T (s)-J · α (s) + Fr · sign (ω (s)) (2)
As can be seen from the above equation (2), the inertia J and static friction Fr of the electric motor 5 are obtained in advance as constants, so that the self-aligning torque is obtained from the motor angular velocity ω, rotational angular acceleration α, assist torque Tm, and steering torque T. The SAT can be estimated. Here, the assist torque Tm is proportional to the steering assist current command value I _M ^*, to apply a steering assist current command value I _M ^* in place of the assist torque Tm.

Then, the inertia compensation value Ii calculated by the inertia compensation unit 52 and the self-aligning torque SAT calculated by the SAT estimation feedback unit 53 are added by the adder 54, and the addition output of the adder 54 and the convergence compensation unit 51 are added. Is added by the adder 55 to calculate a command compensation value Icom, and this command compensation value Icom is output from the steering assist torque command value calculator 42A. _The compensated torque command value I _M ^* ′ is calculated by adding to _M ^* by the adder 56, and this compensated torque command value I _M ^* ′ is output to the dq-axis current command value calculation unit 42C.

The dq-axis current command value calculation unit 42C includes a d-axis target current calculation unit 61 that calculates a d-axis target current Id ^* based on the post-compensation steering assist torque command value I _M ^* ′ and the motor angular velocity ω. Induced voltage model calculation for calculating the d-axis EMF component ed (θ) and the q-axis EMF component eq (θ) of the dq-axis induced voltage model EMF (Electro Magnetic Force) based on the motor rotation angle θ and the motor angular velocity ω. Unit 62, the d-axis EMF component ed (θ) and the q-axis EMF component eq (θ) output from the induced voltage model calculation unit 62, and the d-axis target current Id ^* output from the d-axis target current calculation unit 61 ^. A q-axis target current calculation unit 63 that calculates a q-axis target current Iq ^* based on the post-compensation steering assist torque command value I _M ^* ′ and the motor angular velocity ω, and d output from the d-axis target current calculation unit 61 axis target current Id ^* and the q-axis target current calculation Q-axis target current output from Part 63 Iq ^* and a 3-phase current command value Ia ^*, and a 2-phase / 3-phase conversion unit 64 for converting the Ib ^* and Ic ^*.

The counter electromotive voltage calculation unit 46 first calculates the following expressions (3) to (5) based on the phase terminal voltages Va to Vc input from the terminal voltage detection circuit 8 to perform the line voltage Vab. , Vbc, Vca are calculated.
Vab = Va−Vb (3)
Vbc = Vb−Vc (4)
Vca = Vc−Va (5)

  Next, based on the calculated line voltages Vab, Vbc, Vca and the respective phase current detection values Ia to Ic inputted from the current detection circuit 7, the following expressions (6) to (8) are calculated, and each line is calculated. The back electromotive force voltages EMFab, EMFbc, and EMFCa are calculated.

EMFab = Vab − {(Ra + s · La) · Ia− (Rb + s · Lb) · Ib} (6)
EMFbc = Vbc − {(Rb + s · Lb) · Ib− (Rc + s · Lc) · Ic} (7)
EMFCa = Vca − {(Rc + s · Lc) · Ic− (Ra + s · La) · Ia} (8)
Here, Ra, Rb, and Rc are winding resistances of the motor, La, Lb, and Lc are inductances of the motor, and s is a Laplace operator, which represents a differential operation (d / dt) here.

Then, the back electromotive force EMF (= | EMFab | + | EMFbc | + | EMFca |) is calculated by adding the absolute values of the calculated line back electromotive voltages EMFab, EMFbc, and EMFCa. Here, the reason why the back electromotive voltage EMF is obtained by adding the absolute values of the line back electromotive voltages EMFab, EMFbc, and EMFCa is to simplify the calculation, and to improve the relative angle calculation accuracy, To obtain EMF, the square root of the sum of squares of the back electromotive force voltages EMFab, EMFbc and EMFCa, that is, EMF = √ (EMFab ² + EMFbc ² + EMFca ² ) is calculated. The required line back electromotive voltages EMFab, EMFbc, and EMFCa may be accurate enough to obtain a relative angle of the motor.

Further, the motor rotation angle calculation unit 47 executes a motor rotation angle calculation process (not shown) every time the peak detection pulse Pp is input from the motor rotation angle detection circuit 32, calculates sin θ and cos θ, and calculates the calculated sin θ and A motor rotation angle θe, which is an electrical angle, is calculated from cos θ.
Further, as shown in FIG. 15, the angular velocity / angular acceleration calculating unit 48 includes a relative angular velocity calculating unit 48a that calculates a relative angular velocity ωee based on the counter electromotive voltage EMF input from the counter electromotive voltage calculating unit 46, and the relative angular velocity calculating unit 48a. A rate limiter unit 48d that suppresses a rapid change in the relative angular velocity ωee output from the angular velocity calculation unit 48a, and a code acquisition unit 48b that acquires a code representing the rotational direction based on the steering torque Ts input from the steering torque sensor 17. And a rotation direction determination unit 48e that enables generation of alternative relative angle information, which will be described later, and further, a code (relative angle integration direction) acquired by the rotation direction determination unit 48e is used as a rate limiter unit. A multiplying unit 48c that multiplies the absolute value of the relative angular velocity ωee, whose sudden change is suppressed by 48d, and the relative angular velocity ωee output from the multiplying unit 48c. And an addition unit 48f for calculating a relative rotation angle θee is added to the motor rotation angle θe (n-1).

  Further, the angular velocity / acceleration calculation unit 48 includes a complementary relative angle information calculation unit 70 that calculates a complementary relative rotation angle θee ′ based on the steering torque Ts detected by the steering torque sensor 17. The relative angle information calculation unit 70 supplies the complementary relative rotation angle θee ′ directly to one input side of the second rotation angle selection unit 48n and also supplies it to the angular velocity calculation unit 48o. The relative rotation angle θee output from the adder 48f is input to the other input side of the second rotation angle selector 48n. The output of the second rotation angle selector 48n is switched by the detection signal of the dead zone detector 48m, and the relative rotation angle θee selected by the second rotation angle selector 48n is one input side of the rotation angle selector 48g. To be supplied.

  The angular velocity calculation unit 48o differentiates the complementary relative rotation angle θee ′ calculated by the complementary relative angle information calculation unit 70 to calculate the complementary angular velocity ωee ′, and one input of the second angular velocity selection unit 48p. Supply to the side. Further, the relative angular velocity ωee output from the multiplying unit 48c is supplied to the other input side of the second angular velocity selecting unit 48p, and the second angular velocity selecting unit 48p is detected by the dead zone detecting unit 48m. The output is switched by the signal, and the relative angular velocity ωee selected by the second angular velocity selecting unit 48p is supplied to one input side of the angular velocity selecting unit 48i.

  That is, the dead zone detector 48m outputs a detection signal SD having a logical value “0” when the relative angular velocity ωee is outside the dead zone, and outputs a detection signal SD having a logical value “1” when the relative angular velocity ωee is outside the dead zone. Are output to the rotation angle selector 48n and the second angular velocity selector 48o. The second rotation angle selection unit 48n selects the relative rotation angle θee output from the addition unit 48f when the detection signal SD is the logical value “0”, and complements the relative rotation angle when the detection signal SD is the logical value “1”. The complementary relative rotation angle θee ′ calculated by the angle information calculation unit 70 is selected. The second angular velocity selection unit 48p selects the relative angular velocity ωee output from the multiplication unit 48c when the detection signal SD is a logical value “0”, and the angular velocity calculation unit 48o when the detection signal SD is a logical value “1”. The calculated complementary relative angular velocity ωee ′ is selected.

  Further, the angular velocity / angular acceleration calculation unit 48 uses the relative rotation angle θee selected by the second rotation angle selection unit 48n and the actual rotation angle θer input from the motor rotation angle calculation unit 47 as a fail-safe processing unit 49. A rotation angle selection unit 48g as selection means for selection based on the fail safe signal SF, an angular velocity calculation unit 48h for differentiating the actual rotation angle θer input from the motor rotation angle calculation unit 47 and calculating the actual angular velocity ωer; The angular velocity selection unit 48i that selects the actual angular velocity ωer input from the angular velocity calculation unit 48h and the complementary relative angular velocity selected by the second angular velocity selection unit 48p based on the fail-safe signal SF, and the angular velocity selection And an angular acceleration calculation unit 48j that calculates the angular acceleration α by differentiating the angular velocity ωe selected by the unit 48i.

  Here, the rotation angle selector 48g selects the actual rotation angle θer input from the motor rotation angle calculator 47 when the fail safe signal SF input from the fail safe processor 49 is a logical value “0”. When the logical value is “1”, the relative rotation angle θee input from the second rotation angle selection unit 48n is selected. Similarly, the angular velocity selection unit 48i selects the actual angular velocity ωer input from the angular velocity calculation unit 48h when the fail safe signal SF input from the fail safe processing unit 49 is the logical value “0”, and the logical value “1”. If "," the relative angular velocity ωee input from the second angular velocity selecting unit 48p is selected.

Here, the complementary relative angle information calculation unit 70 performs the complementary relative angle calculation process shown in FIG. This complementary relative angle calculation process is executed as a timer interrupt process for every predetermined time (for example, 1 msec). First, the process proceeds to step S51, and after reading the steering torque Ts, the process proceeds to step S52. In step S52, the transition from performing an averaging process to calculate an average value Ts _M of the steering torque Ts of I read including a steering torque Ts previous predetermined number (e.g. 32) minutes to step S53.

In step S53, the steering torque average value Ts _M calculated in the step S52 is, dead zone preset steering assist control, i.e., electric power e.g. reducer efficiency of the steering mechanism, a rack and pinion efficiency and the like mechanical dead zone It is determined whether or not it is within the dead band in the electric power steering mechanism determined by the setting including the step. If it is within the dead band, the process proceeds to step S54, and the steering torque average value Ts _M is changed to “0” and then the step is performed. The process proceeds to S55, and if it is outside the dead zone, the process proceeds to Step S55 as it is.

In step S55, the current steering torque average value Ts _M (n) and the steering torque average value during previous sampling made by the steering torque average value Ts _M was changed by the steering torque average value Ts _M or step S54 is calculated at step S52 It is determined whether or not the amount of change ΔT with respect to Ts _M (n−1) exceeds a preset upper limit value ΔTu. If ΔT> ΔTu, it is determined that the amount of change ΔT is too large, and the process proceeds to step S56. Then, a value obtained by adding the upper limit value ΔTu to the previous steering torque average value Ts _M (n−1) is set as the current steering torque average value Ts _M (n), and then the process proceeds to step S57, where ΔT ≦ ΔTu. If there is, it is determined that the change amount ΔT is within the allowable range, and the process directly proceeds to step S57. Note that the processing in steps S55 and S56 is a limiter processing for limiting the change amount ΔT. In this case, the upper limit value ΔTu is set to an optimum value according to the vehicle speed Vs even if it is a predetermined value. May be.

In step S57, the calculation of the following equation (9) is performed to calculate the motor relative angle change amount Δθ _M , and then the process proceeds to step S58.
Δθ _M = Ts _M (n) · Km / 2 ¹² (9)
Here, Km is a relative angle information calculation gain.
In step S58, the motor relative angle change amount Δθ _M calculated in step S57 and the motor relative angle θ _MP (n−1) calculated in the previous sampling are added to obtain the current motor relative angle θ _MP (n). After the calculation, the process proceeds to step S59. In step S59, the motor relative angle θ _MP (n) is converted into, for example, a 12-bit electrical angle 0 to 4096 and stored in a predetermined storage area of the RAM built in the microcomputer 30, and the timer interrupt process is terminated.

  Further, the fail-safe processing unit 49 executes a motor rotation angle abnormality detection process shown in FIG. This motor rotation angle abnormality detection process is executed as a timer interruption process every predetermined time (for example, 10 msec). First, in step S21, the sine wave sin θ and cosine wave cos θ calculated by the motor rotation angle calculation process (not shown) are used. Then, the process proceeds to step S22 to determine whether the combination of the sine wave sin θ and the cosine wave cos θ is normal or abnormal with reference to the abnormality determination map based on the sine wave sin θ and the cosine wave cos θ.

Here, as shown in FIG. 18, the abnormality determination map has a configuration in which sin θ is taken on the horizontal axis and cos θ is taken on the vertical axis, and three concentric circles around the origin G (0, 0) and 2 Two rectangles are displayed. First, three concentric circles will be described. The innermost side is (sin θ) ² + (cos θ) ² = Pmin, the middle is (sin θ) ² + (cos θ) ² = 1, and the outermost side is (sin θ) ² + (cos θ ) ² = Pmax circle is displayed. The large square α is a square with a side of 2 · Pmax, and the small square β is a square with a side of 2 (Pmin / √2). Here, the normal area indicates a hatched area surrounded by a large rectangle α and a small rectangle β, and the other areas indicate an abnormal range. Note that Pmin and Pmax of the determination criteria described above can adjust the abnormality detection accuracy by Pmax and Pmin in consideration of the influence of detection accuracy, the number of poles of the motor, and the like. By appropriately setting Pmax and Pmin, it is possible to detect a failure during driving of the motor and an abnormality of the resolver 18. (Sin θ) ² + (cos θ) ² = 1 is a normal normal criterion, and (sin θ) ² + (cos θ) ² = Pmin and (sin θ) ² + (cos θ) ² = Pmax are Pmin <( sin θ) ² + (cos θ) ² <Pmax, indicating a normal range, which is wider than the normal normal criterion.

Next, if the determination result of step S22 is that sin θ and cos θ are normal, the process proceeds to step S23, and the fail-safe signal SF having a logical value “0” indicating normal is sent to the angular velocity / acceleration calculation unit 48. The timer interrupt process is terminated, and if sin θ and cos θ are abnormal, the process proceeds to step S24, and the fail-safe signal FS having a logical value “1” indicating the abnormality is sent to the angular velocity / angle. After outputting to the acceleration calculation unit 48, the timer interruption process is terminated. In this manner, by using the abnormality determination map to determine whether sin θ and cos θ are normal or abnormal, (sin θ) ² + (cos θ) ² = 1 for determining (sin θ) ^It is not necessary to calculate ² + (cos θ) ² , the processing load on the microcomputer 30 can be greatly reduced, and the determination time can be greatly shortened.

Then, the microcomputer 30 executes a steering assist control process shown in FIG. 19 corresponding to the current command value calculation unit 42 based on each input signal.
As shown in FIG. 19, in this steering assist control process, first, in step S 1, the detected values of various sensors such as the steering torque sensor 17 and the vehicle speed sensor 33 and the rotation angle θe output by the angular velocity / angular acceleration calculation unit 48. Then, the angular velocity ωe and the angular acceleration α are read, and then the process proceeds to step S2, and the steering assist torque command value I _M ^* is referred to based on the steering torque T with reference to the steering assist torque command value calculation map shown in FIG. After calculating, the process proceeds to step S3.

  In step S3, the convergence angle compensation value Ic is calculated by multiplying the motor angular velocity ωe by the compensation coefficient Kv set in accordance with the vehicle speed V in the same manner as the convergence compensation unit 51, and then the process proceeds to step S4. In step S4, as in the inertia compensation unit 52, the inertia compensation value Ii is calculated based on the motor angular acceleration α, and then, in step S5, the motor angular velocity ωe and the motor angular acceleration α are shifted in the same manner as in the SAT estimation feedback unit 53. The self-aligning torque SAT is calculated by performing the calculation of the above-described equation (2) based on the above.

Next, the process proceeds to step S6, where the post-compensation steering assist torque is obtained by adding the convergence compensation value Ic, inertia compensation value Ii and self-aligning torque SAT calculated in steps S3 to S5 to the steering assist torque command value I _M ^*. The command value I _M ^* 'is calculated, and then the process proceeds to step S7, and the compensated steering assist torque command value I _M ^* ' calculated in step S6 is changed to dq similar to the dq axis current command value calculation unit 42B. The axis command value calculation process is executed to calculate the d-axis target current Id ^* and the q-axis target current Iq ^* , and then the process proceeds to step S8 to perform a two-phase / three-phase conversion process to obtain a motor current command value Ia ^* ˜ Ic ^* is calculated.

Next, the process proceeds to step S9, where the motor currents Ia to Ic are subtracted from the motor current command values Ia ^{* to} Ic ^* to calculate the current deviations ΔIa to ΔIc, and then the process proceeds to step S10 and the current deviations ΔIa to ΔIc. The voltage control values Va ^{* to} Vc ^* are calculated by performing the PI control process for the motor, and then the process proceeds to step S11 to output the calculated voltage command values Va ^{* to} Vc ^* to the FET gate drive circuit 22 of the motor drive circuit 6. Then, the steering assist control process is terminated and the process returns to a predetermined main program.

  Here, the electric power steering apparatus of the present embodiment is assumed to be disconnected, shorted, ground fault, power fault, etc. in the resolver 18, the motor rotation angle detection circuit 32, and the motor rotation angle detection system of the A / D converters 35 and 36. An alternative to execute alternative relative angle information calculation processing that enables generation of alternative relative angle information even when the motor relative angle information calculation unit cannot obtain relative angle information due to occurrence of an abnormality A relative angle information calculation unit is provided. The angular velocity / acceleration calculation unit 48 corresponds to a motor relative angle determination unit, of which a back electromotive force calculation unit 46, a relative angular velocity calculation unit 48a, a code acquisition unit 48b, a rate limiter unit 48d, a rotation direction determination unit 48e, and The multiplication unit 48c corresponds to the alternative relative angle information calculation unit. The motor rotation angle calculation unit 47 and the angular velocity calculation unit 48h correspond to a motor relative angle information calculation unit.

  Specifically, when the alternative relative angle information calculation process is executed as a timer interrupt process at predetermined time intervals (for example, 1 msec) in the microcomputer 30, first, the counter electromotive voltage EMF calculated by the counter electromotive voltage calculation unit 46 is read. Next, the relative angular velocity ωee is calculated based on the back electromotive force EMF, then the sign of the steering torque Ts is obtained, and the rotational direction is changed to the relative angular velocity ωee based on predetermined processing and determination in the rotation direction determination unit 48e. Is added.

That is, the relative angular velocity calculation unit 48a calculates the relative angular velocity ωee by performing the calculation of the following equation (10) based on the counter electromotive voltage EMF input from the counter electromotive voltage calculation unit 46.
ωee = EMF / Ke (10)
Here, Ke is a back electromotive force constant [V / rpm] of the motor.
A dead zone setting unit (not shown) in the back electromotive voltage calculation unit 46 calculates the line back electromotive voltages EMFab, EMFbc, and EMFCa described above, and the winding resistances Ra to Rc of the motors of the equations (6) to (8). Since the model value of the resistance is adopted instead of the actual resistance value, an error occurs in the relative angular velocity ωee, and the dead band setting proportional to the current is set based on the fact that the error becomes an offset error proportional to the motor current. To eliminate the estimation error. That is, the relative angular velocity ωee is proportional to the current (counterelectromotive voltage), and the error is also proportional to the current (counterelectromotive voltage). For this reason, the set value of the dead zone is set to a value corresponding to the current command value I _M ^* or the actual current value.

Next, the rotation direction determination unit 48e will be described in detail. FIG. 20 is a block diagram showing an internal calculation block of the rotation direction determination unit 48e.
The rotational direction determination unit 48e is a relative angular amount (relative velocity amount) calculated by the angular velocity calculation unit 48a, that is, rotation direction information (relative angle integration direction) added to the relative angular velocity ωee calculated by the relative angular velocity calculation unit 48a. Information).

  Specifically, as shown in FIG. 20, the rotation direction determination unit 48e includes an absolute angle region setting unit 50a, an intermediate angle shift calculation unit 50b, a region determination unit 50c, and a final rotation direction determination unit 50d. ing. In the rotation direction determination unit 48e, the four internal calculation blocks 50a, 50b, 50c, and 50d are executed by the microcomputer 30 as a series of rotation direction determination processes in this order.

  The absolute angle area setting unit 50a is an absolute angle area setting unit that executes the absolute angle area setting process shown in FIG. In other words, when the absolute angle region setting process is executed by the microcomputer 30, the absolute angle region setting unit 50a first proceeds to step S101 as shown in FIG. The line back electromotive force value EMF thus read is read, and the process proceeds to step S102. In step S102, the maximum absolute value of each line back electromotive voltage EMF is compared with a predetermined threshold. This predetermined threshold value is set in advance so that when the electric motor is running at a low speed, each line back electromotive voltage is small, and a value that is considered to be low in reliability of the acquired value of the sign relationship is set as a determination dead zone . When the maximum absolute value of each line back electromotive voltage EMF is equal to or greater than the predetermined threshold (NO), the process proceeds to step S103. In step S103, the state value “F = 0” of the determination dead zone is output, and the process proceeds to step S105. On the other hand, when the maximum absolute value of each line back electromotive voltage EMF is less than the predetermined threshold (YES), the process proceeds to step S104, and in step S104, the state value “F = 1” of the determination dead zone is obtained. "And return the process. Then, in step S105, when the rotation of the electric motor in the predetermined direction is the forward rotation, the sign of each line back electromotive voltage at the time of forward rotation is obtained from each line back electromotive voltage value EMF. Based on the relationship table (see Table 2 below), the process proceeds to step S106. In step S106, an estimated absolute angle region in which the electrical angle is divided every 60 ° with reference to the time of forward rotation is calculated. The calculated intermediate angle θc of the estimated absolute angle region is output and the process returns.

  The subsequent intermediate angle shift calculation unit 50b is intermediate angle shift calculation means for executing the intermediate angle shift calculation process shown in FIG. 22, and calculates the change in the intermediate angle θc output from the absolute angle region setting unit 50a. Determine the direction of transition. If the transition is to an adjacent region, a new post-shift intermediate angle θc sht obtained by shifting the intermediate angle θc according to the transition direction is output.

  Specifically, when the intermediate angle shift calculation process is executed in the microcomputer 30, the intermediate angle shift calculation unit 50b first proceeds to step S201 as shown in FIG. Is calculated as the area transition information. When there is no difference (YES), that is, when there is no transition of the intermediate angle θc, the process shifts to step S203 to output the past shifted intermediate angle θc sht as it is and return the process. On the other hand, in step S201, when there is a difference between the current intermediate angle θc and the previous intermediate angle θc (NO), if there is a shift to an adjacent region in the positive rotation direction, the process proceeds to step S204.

  In step S204, if the difference value is 60 (deg el) or -300 (deg el)) (YES), the process proceeds to step S205, and in step S205, the intermediate angle θc is set to -30 (deg el ) Is output as the shifted intermediate angle θc sht and the process is returned. On the other hand, if the difference value is not 60 (deg el) or -300 (deg el) in step S204 (NO), the process proceeds to step S206. In step S206, determination is made regarding the transition to the adjacent area in the reverse direction. That is, when the change in the intermediate angle θc is −60 (deg el) or 300 (deg el)), the process proceeds to step S207, and in step S207, the intermediate angle θc is increased to +30 (deg el). The shifted value is output as the intermediate angle θc sht after the shift, and the process is returned. Further, when the difference value is other than the above in step S206 (NO), the process proceeds to step S208, and in step S208, the value of the intermediate angle θc output from the absolute angle region setting unit 50a is directly shifted to the intermediate value. Output as angle θc sht and return processing.

The subsequent area determination unit 50c executes an area determination process shown in FIG. That is, when the area determination process is executed by the microcomputer 30, as shown in FIG. 23, first, the process proceeds to step S301 to calculate the temporary estimated electrical angle θee ″, and the process proceeds to step S302.
Here, the estimated electrical angle itself cannot be calculated because the current rotation direction is not determined. In view of this, the region determination unit 50c uses the estimated electrical angle calculated last time and the previously calculated relative angle information (rotation direction information and relative angular velocity information) to provide a temporary estimated electrical angle corresponding to the current estimated electrical angle. θee ″ is calculated. That is, the temporary estimated electrical angle θee ″ is calculated by the previous rotation angle θee (n−1) + the previous rotation direction × the absolute value of the relative angular velocity ωee. In step S302, the temporary estimated electrical angle θee ″ is converted into the post-shift intermediate angle θc sht ± using the post-shift intermediate angle θc sht and the temporary estimated electrical angle θee ″ output from the intermediate angle shift unit 50b. 90 (deg el)) is within the range of the determination angle region (YES), the process proceeds to step S304 to output a positive direction rotation signal (d = 1) and out of the determination angle region. If (NO), the process proceeds to step S303 to output a reverse rotation signal (d = -1) and return the process.

  The subsequent final rotation direction determination unit 50d executes a final rotation direction determination process shown in FIG. That is, when the final rotation direction determination process is executed by the microcomputer 30, the final rotation direction determination unit 50d first proceeds to step S401 as shown in FIG. In step S401, if the dead zone is F (F = 1) according to the determination dead zone state F (YES), the process proceeds to step S403, the sign of the steering torque is obtained from the sign obtaining unit 48b, and the process proceeds to step S404. In step S404, the steering torque direction is set as the relative angle integration direction, and this is output as the final rotation direction d last to return the processing to the main program. On the other hand, in the determination in step S401, if the dead zone (F = 0) (NO), the process proceeds to step S402, and in step S402, the rotational direction determination value d output from the region determination unit 50c is set as a relative value. The angle integration direction is set, this is output as the final rotation direction d last, and the process is returned to the main program.

Next, the operation of this electric power steering apparatus and its operation and effect will be described.
Now, by turning on the ignition switch 37 shown in FIG. 10, the power from the battery 1 is turned on to the control device 3, and the microcomputer 30 in the control device 3 detects the abnormality in the motor rotation angle shown in FIG. The processing, a steering assist control process shown in FIG. 19, a series of processes related to the calculation of relative angle information shown in FIG.

  At this time, assuming that the motor rotation angle detection system such as the resolver 18, the motor rotation angle detection circuit 32, and the A / D converters 35 and 36 is normal, when the motor rotation angle abnormality detection process of FIG. 11, sin θ calculated based on the sine wave signal (sin ωt + sin θ) and cosine wave signal (sin ωt + cos θ) input from the motor rotation angle detection circuit 32 and the peak detection pulse Pp in the motor rotation angle calculation unit 47 shown in FIG. Cos θ is read (step S21), and by referring to the abnormality determination map shown in FIG. 18 based on the read sin θ and cos θ, the points represented by sin θ and cos θ enter the normal region indicated by hatching. As a result, the motor rotation angle detection system is determined to be normal, and a fail safe signal SF having a logical value “0” is output to the angular velocity / angular acceleration calculation unit 48 (step S23).

For this reason, in the angular velocity / angular acceleration calculation unit 48 shown in FIG. 15, the rotation angle selection unit 48g selects the actual rotation angle θer calculated by the motor rotation angle calculation unit 47 and sets it as the rotation angle θe. The selection unit 48i selects the actual angular velocity ωer obtained by differentiating the actual rotation angle θer and sets it as the angular velocity ωe. Further, the angular acceleration calculation unit 48j differentiates the angular velocity ωe to calculate the angular acceleration α to rotate these rotations. The angle θe, the angular velocity ωe, and the angular acceleration α are output to the current command value calculation unit 42. The current command value calculation unit 42 outputs the calculated voltage command values Va ^{* to} Vc ^* to the FET gate drive circuit 22 of the motor drive circuit 6 by executing the steering assist control process of FIG.

For this reason, the FET gate drive circuit 22 supplies the three-phase drive current to the electric motor 5 from the motor drive circuit 6 by controlling the pulse width modulation of the field effect transistor of the motor drive circuit 6. A steering assist force in a direction corresponding to the steering torque applied to the steering wheel 11 is generated and transmitted to the output shaft 12 via the reduction gear 13. At this time, in a so-called stationary state in which the steering wheel 11 is steered while the vehicle is stopped, the vehicle speed Vs is zero, and the gradient of the characteristic line of the steering assist command value calculation map shown in FIG. 13 is large. Since a large steering assist command value I _M ^* is calculated with a small steering torque Ts, a light steering can be performed by generating a large steering assist force with the electric motor 5.

  However, for example, when the vehicle is running, the resolver 18, the motor rotation angle detection circuit 32, and the motor rotation angle detection system of the A / D converters 35 and 36 have an abnormality such as disconnection, short circuit, ground fault, or power fault. When this occurs, the sine wave signal (sin ωt + sin θ) and the cosine wave signal (sin ωt + cos θ) input from the motor rotation angle detection circuit 32 to the microcomputer 30 become abnormal, and a motor rotation angle calculation (not shown) is performed based on these and the peak detection pulse Pp. When the combination of sin θ and cos θ calculated by the processing becomes abnormal and the abnormality determination map shown in FIG. 18 is referred to based on sin θ and cos θ in the motor rotation angle abnormality detection processing of FIG. 17, sin θ and cos θ. The point represented by is outside the normal region shown by the hatching. As a result, a fail safe signal SF having a logical value “1” is immediately output from the fail safe processor 49 to the angular velocity / angular acceleration calculator 48.

  The fail safe processing unit 49 outputs the fail safe signal SF having the logical value “1” to the rotation angle selection unit 48g and the angular velocity selection unit 48i illustrated in FIG. Further, when the calculated value of the relative angular velocity ωee based on the back electromotive force EMF is outside the dead zone, the dead zone detection unit 48m generates a dead zone detection signal SD having a logical value “0” as the second rotation angle selection unit 48n and the second angular velocity. The data is output to the selection unit 48p.

Accordingly, the second rotation angle selection unit 48n and the rotation angle selection unit 48g select the relative rotation angle θee calculated by the addition unit 48f, and the second angular velocity selection unit 48p and the angular velocity selection unit 48i. Thus, the relative angular velocity ωee output from the multiplying unit 48c is selected, and the current command value calculating unit 42 is based on the relative rotation angle θe, the relative angular velocity ωe, and the relative angular acceleration α that are calculated based on the back electromotive force EMF. Outputs each phase voltage command value Va ^* , Vb ^*, and Vc ^* to the FET gate drive circuit 22 of the motor drive circuit 6, and the electric motor 5 is driven and controlled in the same manner as described above, so that the steering assist force is supplied from the electric motor 5. Is generated, the steering assist control process is continued.

That is, even if the motor rotation angle detection system fails, when the rotation angle selection unit 48g and the angular velocity selection unit 48i are switched, the relative angle information calculation processing including FIG. By calculating the relative (rotation) angle based on the back electromotive force EMF, the rotation angle θe, the angular velocity ωe, and the angular acceleration α are determined in accordance with alternative relative angle information.
On the other hand, when the relative angular velocity ωee calculated by the relative angular velocity calculating unit 48a is within the dead band in the state where the steering assist control process is continued, the detection signal SD of the logical value “1” is output from the dead band detecting unit 48m to the second rotation angle. By outputting to the selection unit 48m and the second angular velocity selection unit 48p, the complementary relative rotation angle θ _MP calculated by the complementary relative angle information calculation unit 70 and stored in the RAM of the microcomputer 30 is selected. In addition, the relative angular velocity ωee ′ obtained by differentiating the complementary relative rotation angle θee ′ (= θ _MP ) calculated by the angular velocity calculation unit 48o is selected.

For this reason, when the relative angular velocity ωee calculated based on the back electromotive force EMF is within the dead zone in the vicinity of the “0” angular velocity, it is calculated based on the steering torque Ts calculated by the complementary relative angle information calculating unit 70. A complementary relative rotational angle θ _MP and a relative angular velocity ωee ′ that is a differential value thereof are selected, and a relative angular acceleration α that is obtained by differentiating the complementary relative angular velocity ωee ′ is output to the command value calculation unit 42, thereby steering. The steering assist control process can be continued based on the complementary relative rotation angle θ _MP , the complementary relative angular velocity ωee ′, and the relative angular acceleration α while preventing the occurrence of (handle) lock.

  Furthermore, in the present embodiment, the rotation direction determination unit 48e executes a series of rotation direction determination processes in the order of the four internal calculation blocks 50a, 50b, 50c, and 50d. By comparing the positional relationship with θee ″, the rotational direction of the electric motor is changed by rotating in the forward direction if these positional relationships are within the determination angle region, and by rotating in the reverse direction if they are outside the region. Since the estimation is made, it is possible to continue the steering assist control and to prevent or suppress the possibility of causing the steering wheel vibration even when the rotation direction of the electric motor is reversed with respect to the steering torque direction. Therefore, it is possible to further suppress the driver from feeling uncomfortable.

  In particular, the rotation direction determination unit 48e outputs the intermediate angle θc of the estimated absolute angle region described above, and the determination angle region and the temporary estimated electrical angle θee ′ within the range of ± 90 (deg el) from the intermediate angle θc. Since the temporary estimated electrical angle θee '' is determined to be in the forward rotation if it is within the range of the determination angle region, it is determined to be the reverse rotation if it is outside the range of the same region. Since the rotational direction determination range is expanded, stable rotational direction determination is possible even when there is a delay error in the estimated electrical angle (see FIG. 4).

  Further, when setting the angle region for determination, the transition direction when the intermediate angle θc shifts is determined, and a new post-shift intermediate angle θc sht obtained by shifting the intermediate angle θc according to the determined transition direction is calculated. Since the determination angle region is generated using the intermediate angle θc sht after the shift, the determination angle region does not move even if there is hunting when determining the region to the adjacent region. The rotation direction can be determined more stably (see FIGS. 5 to 7).

  Furthermore, there is provided a determination dead zone in which the region determination is not performed unless the maximum value of the back electromotive force value between the lines of the electric motor exceeds a predetermined threshold (see FIG. 21), and the final rotation direction determination is performed. When the maximum value of the back electromotive force value between the lines is present in this determination dead zone, the steering torque direction is adopted and this is set as the relative angle integration direction (see FIG. 24). In the case of rotation, even when the back electromotive force between the lines is small and the reliability of the acquired value of the sign relationship is low, it is possible to perform region determination with high reliability. The reason for setting the steering torque direction as the relative angle integration direction in the determination dead zone is that the direction at the time of initial steering of the steering wheel is substantially the steering torque direction.

  As described above, according to the electric power steering apparatus of the above-described embodiment, it is possible to calculate alternative relative angle information even when a motor rotation angle detection system such as a resolver breaks down, and to calculate steering torque. Even when the rotation direction of the electric motor is reversed with respect to the direction, the possibility of causing the handle vibration is prevented or suppressed, and it is possible to further suppress the driver from feeling uncomfortable.

The electric power steering apparatus according to the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, in the area determination, the range of the shifted intermediate angle ± 90 (deg el) is set as the determination angle area, and based on the previously calculated estimated electrical angle and the previously calculated relative angle information, An example is described in which a temporary estimated electrical angle corresponding to the current estimated electrical angle is calculated as estimated electrical angle information, and the region is determined by comparing the estimated electrical angle information that is the temporary estimated electrical angle with the determination angle region. However, it is not limited to this.

  For example, when the calculation speed of the microcomputer 30 or the like is sufficiently high, instead of the calculated value of the temporary estimated electrical angle, as shown in FIGS. 25 to 27 as a modified example (first modified example) of the above embodiment. In addition, the calculated value of the estimated electrical angle calculated last time may be used as the estimated electrical angle information. That is, as shown in FIG. 25, in this modification, the rotation direction determination unit 48e does not acquire the previous relative angular velocity ωee (n−1). Then, as shown in FIG. 26, the area determination unit 50c, which is an internal calculation block of the rotation direction determination unit 48e, executes the area determination process as shown in step S301 of FIG. 27 without using | ωee |. Then, the previous rotation angle θee (n−1) is used as the temporary estimated electrical angle θee ″. With such a configuration, it is not necessary to perform the temporary estimated electrical angle calculation as compared with the above-described embodiment, so that a reduction in calculation load can be expected.

  Further, for example, in the example of the above embodiment, since the estimated electrical angle is obtained by integration from the relative angle information from the back electromotive voltage value, if noise or the like is mixed in the back electromotive voltage value, the error is accumulated and estimated. The electrical angle error can increase. Here, as shown in the schematic diagram of FIG. 28, when the estimated absolute angle region divided every 60 ° shifts to the adjacent region, the electric angle of the electric motor to be estimated is on the region boundary angle. Exists.

  Therefore, in the second modified example described below, when the estimated absolute angle region obtained by dividing the electrical angle every 60 ° is shifted to an adjacent region using the above, after the transition to the estimated absolute angle region before the transition. In this example, the boundary angle of the estimated absolute angle region is a corrected estimated electrical angle (black triangle sign in FIG. 28), and the estimated electrical angle is corrected to the corrected estimated electrical angle to prevent an increase in the estimated electrical angle error. is there.

  More specifically, in the second modification, as shown in FIG. 29, the angular velocity / angular acceleration calculation unit 48 further includes a correction timing selection unit 48r, and the correction timing selection unit 48r has a rotational direction. It differs from the configuration of the above-described embodiment in that whether or not to correct to the corrected estimated electrical angle is selected according to the correction timing flag with reference to the correction timing flag from the determination unit 48e. .

The rotation direction determination unit 48e in the second modified example further includes an estimated electrical angle correction unit (not shown) as a block diagram in addition to the internal calculation block. A series of estimated electrical angle correction processes as shown in FIG.
This estimated electrical angle correction process is executed as a timer interrupt process for each predetermined time (for example, 1 msec). As shown in FIG. 30, first, in step S501, whether the absolute angle area has shifted to an adjacent area. If not, the process proceeds to step S502. If not (NO), the process proceeds to step S504. In step S502, it is determined whether or not the post-shift reference angle has changed. If so, the process proceeds to step S503. If not (NO), the process proceeds to step S504. In step S503, the correction timing flag is set to “1” (correction allowed), and the process proceeds to step S505. In step S504, the correction timing flag is set to “0” (correction not permitted) (that is, the estimated electrical angle that is not corrected by the correction timing selection unit 48r in FIG. 29 is selected), and the process is returned. .

  In step S505, it is determined whether or not the transition direction of the absolute angle region is the same direction as the predetermined rotation direction. If it is the same direction (YES), the process proceeds to step S506, and if not (NO), the process proceeds to step S507. Transition. In step S506, the process proceeds to step S508 using the boundary angle as the corrected estimated electrical angle. In step S507, the process proceeds to step S508 using the boundary angle + 180 ° as the corrected estimated electrical angle. In step S508, the estimated electrical angle correction is performed (that is, the corrected estimated electrical angle is selected by the correction timing selection unit 48r in FIG. 29), and the process returns.

In the case of the configuration of the second modification, when the estimated absolute angle region obtained by dividing the electrical angle every 60 ° shifts to the adjacent region, the estimated absolute angle region before the transition and the estimated absolute angle region after the transition Since the estimated electrical angle is corrected by using the boundary angle as the corrected estimated electrical angle, an increase in the estimated electrical angle error can be prevented even when noise or the like is mixed in the counter electromotive voltage value.
Further, with the configuration of the second modification, the transition direction when the estimated absolute angle region transitions to the adjacent region is the same direction as the predetermined rotation direction used as the reference when calculating the estimated absolute angle region. In some cases, the boundary angle is set as the corrected estimated electrical angle, and in the case of a different direction, the boundary angle + 180 ° is set as the corrected estimated electrical angle. Therefore, the corrected estimated electrical angle can be accurately calculated.

  Furthermore, the sign relationship of the back electromotive force between the lines is likely to switch near the switching angle of the absolute angle region, and the absolute angle region determination may cause hunting between adjacent regions. Although the direction of the estimated electrical angle may be incorrect because the direction is also hunted, if the configuration of this second modification is used, the timing for correcting the estimated electrical angle changes the intermediate angle after the shift and the estimated absolute angle. Since the region is shifted to an adjacent region, the post-shift intermediate angle is configured not to move during hunting. Therefore, the estimated electrical angle can be corrected more accurately by adding it as a correction timing condition. .

It is a figure explaining the calculation principle of the rotation direction in this invention, The figure (a) is a waveform example of each line back electromotive voltage at the time of forward rotation, The figure (b) is each line at the time of reverse rotation. It is an example of a waveform of a back electromotive force voltage. It is a figure explaining the calculation principle of the rotation direction in this invention, and the figure is an arrangement | positioning figure of each code | cord | chord relation when the content of Table 1 is represented by a polar coordinate system, and the inner circle of the figure is a positive direction. The rotation represents the rotation, and the outer circle in the figure represents the reverse rotation. The shaded display in the figure corresponds to the same shaded display in Table 1, respectively. It is a figure explaining the calculation principle of the rotation direction in this invention. It is a figure explaining the calculation principle of the rotation direction in 1 aspect of this invention. It is a figure explaining the calculation principle of the rotation direction in 1 aspect of this invention. It is a figure explaining the calculation principle of the rotation direction in 1 aspect of this invention. It is a figure explaining the calculation principle of the rotation direction in 1 aspect of this invention. It is a schematic structure figure showing one embodiment of the present invention. FIG. 6 is a characteristic diagram of a steering torque detection signal output from a steering torque sensor. It is a block diagram which shows the specific structure of the control apparatus of FIG. It is a functional block diagram of the microcomputer of a control apparatus. 12 is a block diagram illustrating a specific configuration of a current command value calculation unit in FIG. 11. It is explanatory drawing which shows the steering assistance command value calculation map which shows the relationship between the steering torque used by steering assistance control processing, and a steering assistance command value. It is a schematic diagram with which it uses for description of the self-aligning torque. It is a block diagram which shows the specific structure of the angular velocity and angular acceleration calculating part of FIG. It is a flowchart which shows an example of the complementary relative angle calculation process. It is a flowchart which shows an example of a motor rotation angle abnormality detection processing procedure. It is explanatory drawing which shows the abnormality determination map used in FIG. It is a flowchart which shows an example of a steering assistance control process. It is a block diagram which shows the internal calculation block of a rotation direction determination part. It is a flowchart which shows an example of an absolute angle area | region setting process. It is a flowchart which shows an example of an intermediate | middle angle shift calculation process. It is a flowchart which shows an example of an area | region determination process. It is a flowchart which shows an example of the last rotation direction determination process. It is a block diagram which shows the structure of one modification (1st modification) of an angular velocity and an angular acceleration calculating part. It is a block diagram which shows the example of 1 structure of the rotation direction determination part in a 1st modification. It is a flowchart which shows one structural example of the area | region determination part in a 1st modification. It is explanatory drawing of the principle which correct | amends the estimated electrical angle in a 2nd modification. It is a block diagram which shows one structural example of the angular velocity and angular acceleration calculating part in a 2nd modification. It is a flowchart which shows an example of the estimation electrical angle correction process in a 2nd modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle-mounted battery 3 Control apparatus 5 Electric motor 6 Motor drive circuit 11 Steering wheel 12 Steering shaft 13 Deceleration device 17 Torque sensor 18 Resolver 21 Inverter circuit 22 FET gate drive circuit 30 Microcomputer 32 Motor rotation angle detection circuit 33 Vehicle speed sensor 42 Current command Value calculation unit 42A Steering assist torque command value calculation unit 42B Command value compensation unit 42C dq-axis current command value calculation unit 44 Subtraction unit 45 Current control unit 46 Back electromotive voltage calculation unit 47 Motor rotation angle calculation unit 48 Angular velocity / angular acceleration Calculation unit 48a Relative angular velocity calculation unit 48b Sign acquisition unit 48c Multiplication unit 48d Rate limiter unit 48e Rotation direction determination unit 48f Addition unit 48g Rotation angle selection unit 48h Angular velocity calculation unit 48i Angular velocity selection unit 48j Angular acceleration calculation unit 48m Insensitive Band detection unit 48n Second rotation angle selection unit 48o Angular velocity calculation unit 48p Second angular velocity selection unit 49 Fail safe processing unit 70 Complementary relative angle information calculation unit

Claims (8)

An electric motor that generates a steering assist force for the steering system, a torque detection unit that detects a steering torque transmitted to the steering system, and relative angle information of the electric motor according to a steering amount with respect to the steering system is determined. According to the motor relative angle determination means, the steering torque detected by the torque detection means, the rotational electrical angle detected by the position detector of the electric motor, and the relative angle information determined by the motor relative angle determination means, An electric power steering device comprising a control means for driving and controlling the electric motor,
The motor relative angle determination means cannot obtain relative angle information from a motor relative angle information calculation unit that calculates relative angle information of the electric motor according to a steering amount with respect to the steering system, and the motor relative angle information calculation unit. Even if, on the basis of the information on the back electromotive force between each line of the electric motor and its sign relationship, the relative angular amount necessary for detecting the position of the electric motor and the relative angular integration direction to be rotated are substituted. An alternative relative angle information calculating unit that calculates an estimated electrical angle from the alternative relative angle information.
The alternative relative angle information calculation unit includes:
Based on the sign relationship of the back electromotive force voltage between each line of the electric motor, an estimated absolute angle region in which the electric angle is divided every 60 ° with reference to the time when the electric motor rotates in a predetermined direction is calculated. Absolute angle region setting means for outputting an intermediate angle of the estimated absolute angle region;
Based on the previously calculated estimated electrical angle and the previously calculated relative angle information, a temporary estimated electrical angle corresponding to the current estimated electrical angle is calculated as estimated electrical angle information, and the estimated electrical angle information and the estimated absolute angle region are calculated. Compared with the determination angle region that is a range of ± 90 ° of the intermediate angle, if the estimated electrical angle information is within the range of the determination angle region, the predetermined direction is a relative angle integration direction, An electric power steering apparatus comprising: an area determination unit that sets a direction opposite to the predetermined direction as a relative angle integration direction if outside the determination angle area.   The electric power steering apparatus according to claim 1, wherein the region determination unit uses a previously calculated estimated electrical angle as estimated electrical angle information instead of the temporary estimated electrical angle. When the intermediate angle calculated by the absolute angle region setting unit changes, the alternative relative angle information calculation unit calculates a new post-shift intermediate angle obtained by shifting the intermediate angle based on the change amount and the transition direction. It further has an intermediate angle shift calculation means for outputting,
The region determination means sets a range of ± 90 ° of the shifted intermediate angle output from the intermediate angle shift calculation means as a determination angle region, compares the determination angle region with the estimated electrical angle information, If the estimated electrical angle information is within the range of the determination angle region, the predetermined direction is the relative angle integration direction. If the estimated electrical angle information is outside the range of the determination angle region, the reverse direction of the predetermined direction is the relative angle. The electric power steering apparatus according to claim 1, wherein the electric power steering apparatus is set in an integration direction.   The alternative relative angle information calculation unit is provided with a determination dead zone in which the region determination unit does not perform the region determination unless the maximum value of each line back electromotive voltage value of the electric motor exceeds a predetermined threshold. When there is a maximum value of the back electromotive voltage value between the lines in the determination dead zone, the steering torque direction is set as the relative angle integration direction based on the steering torque detected by the steering torque detecting means, and 4. The electric power steering apparatus according to claim 3, further comprising a final rotation direction determination unit that sets a result of determination by the region determination unit as a relative angle integration direction when there is no maximum electromotive voltage value.   Determination that the alternative relative angle information calculation unit does not perform the region determination by the region determination unit unless the value of the second largest phase of each line back electromotive voltage value of the electric motor exceeds a predetermined threshold value When there is a dead zone and the judgment dead zone has the second largest phase back electromotive force value, the steering torque direction is calculated based on the steering torque detected by the steering torque detecting means. And a final rotation direction determination unit that uses the determination result by the region determination unit as a relative angle integration direction when there is no second largest value of each line back electromotive voltage value in the determination dead zone. The electric power steering apparatus according to claim 3.   The alternative relative angle information calculation unit, when the estimated absolute angle region has transitioned to an adjacent region, the boundary angle between the estimated absolute angle region before the transition and the estimated absolute angle region after the transition as a corrected estimated electrical angle, The electric power steering apparatus according to any one of claims 3 to 5, wherein the estimated electrical angle is corrected to the corrected estimated electrical angle.   The alternative relative angle information calculation unit, when the transition direction when the estimated absolute angle region has shifted to an adjacent region is the same direction as the predetermined rotation direction used as a reference when calculating the estimated absolute angle region, The electric power steering apparatus according to claim 6, wherein the boundary angle is set as a corrected estimated electrical angle, and if the boundary angle is a different direction, the boundary angle + 180 ° is set as a corrected estimated electrical angle.   The alternative relative angle information calculation unit is characterized in that the timing for correcting the estimated electrical angle is when the post-shift intermediate angle changes and the estimated absolute angle region shifts to an adjacent region. The electric power steering apparatus according to 6 or 7.

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