JP2008087756A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a driver from feeling uncomfortable by employing a motor rotating angle detecting means by a simple constitution to suppress an increase in the number of parts and cost. <P>SOLUTION: An electric power steering device comprises a motor relative angle detecting means 48. The motor relative-angle detecting means 48 further comprises: motor relative angle information calculating parts 48a-48c for calculating the relative angle information of an electric motor according to a steering stroke of a driver with respect to a steering system; and a relative angle information compensating part 48e for preventing the motor relative angle information calculating parts from being brought into a state that the relative angle information calculating part cannot acquire the relative angle information, and thereby allowing the generation of the relative angle information at all times. A motor control means controls the drive of the electric motor of the electric power steering device from an optional actual angle without setting an initial angle in the start of the drive on the basis of the relative angle information detected by the motor relative angle detecting means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus that generates a steering assist force according to a steering torque input to a steering system.

  In this type of electric power steering device, for example, the position of the motor is detected by a position detection procedure, and the amplitude value of the position signal output from the position detection procedure by the abnormality detection procedure is changed to the rotation angle position of the motor. The position detection procedure is detected based on the presence or absence of a fluctuation depending on whether the position detection procedure is less than a predetermined value, and the abnormality detection procedure detects an abnormality in the position detection procedure. A torque control procedure is executed at a rotational angle position where the amplitude value of the position signal is greater than or equal to a predetermined level according to a change, and torque for assisting steering force is output, and the amplitude value of the position signal is less than or equal to a predetermined level. At the rotational angle position of the motor, the torque zero control procedure is executed and the output torque is set to zero. Even tearing state, the steering wheel has been known an electric power steering device for preventing be rapidly returned by the reaction force due to the vehicle state (e.g., see Patent Document 1).

  Also, when an abnormality occurs in the rotor position detection function and the brushless motor is rotating, control is performed to switch the current direction of the electromagnetic coil in order with a preset fixed pattern, and the brushless motor stops. A control device for a brushless motor for a vehicle has been proposed in which a drive signal is gradually switched from a low frequency to a high frequency to activate a brushless motor (see, for example, Patent Document 2).

Furthermore, the output of the reference wave generator that generates a sine wave with a peak value corresponding to the steering torque and the output of the error amplifier that amplifies the deviation between this and the motor current are input to the phase comparator and the phase comparison output. There is also proposed a vehicle steering apparatus that drives a brushless motor without using a rotation angle sensor by configuring a PLL circuit with a voltage controlled oscillator that outputs a voltage controlled output to a reference wave generator. (For example, see Patent Document 3).
Japanese Patent No. 36000805 (first page, FIG. 7) Japanese Patent Laying-Open No. 2005-253226 (first page, FIG. 2) Japanese Patent Laying-Open No. 2003-40119 (first page, FIG. 2)

However, in the conventional example described in Patent Document 1 described above, for example, when the vehicle is in a turning state and the steering wheel is turned up and the correction rudder in the direction is applied, the steering wheel reaction force is assisted by the electric power steering. There is an unsolved problem that the size is the same as that of the unobtainable state and the driver is uncomfortable.
Further, in the conventional example described in the above-mentioned Patent Document 2, when the motor is driven with a predetermined pattern when the position detection sensor becomes abnormal as the electric power steering device, the driver's intention is On the other hand, there is a possibility that the steering wheel rotates, and there is an unsolved problem that the motor drive according to the will of the driver cannot be performed.

Furthermore, in the conventional example described in Patent Document 3, it is assumed that the motor used for the electric power steering is particularly easy to rotate the steering wheel when the power is off, and the vehicle is stopped. Since the position of the steering wheel at the time cannot be specified, the initial angle of the motor cannot be assumed, and it is impossible to completely prevent the driver from feeling uncomfortable. Although it is conceivable to use the conventional example as an alternative control device when the motor rotation angle detection is abnormal, in this case, an analog circuit configuration based on sensorless drive is provided by providing a PLL circuit in addition to the normal control circuit configuration. This requires a high-performance processing unit that can perform the same or equivalent calculations, increasing the number of parts and cost. There is an unsolved problem in that increase.

  In addition to the above, various sensorless brushless motor driving methods using a counter electromotive force proportional to the angular velocity have been proposed. However, it is difficult to control near zero speed, and very high-speed calculation is required for realization. There is a known example that requires a CPU capable of performing the above and requires a very complicated and difficult algorithm. Moreover, since many of the known examples are based on the premise that the brushless motor continues to rotate in a certain direction (reversal of the rotation direction is premised on a method such as switching the rotation direction with a switch), the electric power steering device As such, it is not suitable for master / slave control, or if it is to be applied, a CPU that can perform very high-speed computation is required, which causes a cost increase.

For this reason, an electric power steering device that is controlled using an angle detector under normal conditions, such as when the angle detector becomes abnormal, such as when angle information cannot be obtained correctly, the sensorless motor There is an unsolved problem that driving cannot be performed and there is no other way but to activate the fail safe and stop the steering assist control.
Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the conventional example, and it is possible for the driver to use a motor relative angle detection means having a simple configuration that suppresses an increase in the number of parts and an increase in cost. An object of the present invention is to provide an electric power steering device that can suppress discomfort.

  In order to achieve the above object, an electric power steering apparatus according to a first aspect of the present invention includes an electric motor that generates a steering assist force for a steering system, and steering torque detection means that detects a steering torque transmitted to the steering system. And a motor control means for calculating a steering assist command value based on the steering torque detected by the steering torque detecting means and drivingly controlling the electric motor based on the calculated steering assist command value. A motor relative angle information calculation unit that calculates relative angle information of the electric motor according to a steering amount of the driver with respect to the steering system, and a state in which the motor relative angle information calculation unit cannot obtain relative angle information. A motor relative angle detecting means having a relative angle information complementing unit that can always generate relative angle information by preventing Is configured to drive and control the electric motor from an arbitrary actual angle without setting an initial angle at the start of driving based on relative angle information detected by the motor relative angle detecting means. .

  The electric power steering apparatus according to claim 2 is transmitted to the steering system, an electric motor that generates a steering assist force for the steering system, motor rotation angle detection means that detects a rotation angle of the electric motor, and the like. Steering torque detecting means for detecting steering torque, and a steering assist command value is calculated based on the steering torque detected by the steering torque detecting means, and the calculated steering assist command value and motor rotation detected by the motor rotation angle detecting means An electric power steering apparatus comprising: a motor control unit that drives and controls the electric motor based on an angle; a motor rotation angle abnormality detection unit that detects an abnormality of the motor rotation angle detection unit; A motor relative angle information calculation unit that calculates relative angle information of the electric motor according to a steering amount with respect to a steering system, and the motor relative angle information calculation unit includes a relative angle A motor relative angle detection unit having a relative angle information complementing unit that prevents generation of information and always generates relative angle information, and the motor control unit includes the motor rotation angle. When the abnormality detection means does not detect the abnormality of the motor rotation angle abnormality detection means, the motor rotation angle information detected by the rotation angle detection means is selected, and the motor rotation angle abnormality detection means selects the motor rotation angle. When detecting abnormality of the detecting means, the relative angle information detected by the motor relative angle detecting means is selected, and the electric motor is driven and controlled based on the selected motor rotation angle information or relative angle information. It is characterized by being.

Further, according to a third aspect of the present invention, there is provided the electric power steering apparatus according to the second aspect of the present invention, wherein the motor control means arbitrarily sets an initial angle when driving the electric motor based on the relative angle information. It is characterized by being configured to drive from the actual angle.
Furthermore, the electric power steering device according to claim 4 is the invention according to any one of claims 1 to 3, wherein the motor relative angle information complementing unit is calculated by the relative angle calculated by the motor relative angle information calculating unit. The information is configured to prevent the relative angle information from being obtained by adding an offset value that changes the sign for each predetermined period when necessary.

  Still further, the electric power steering apparatus according to claim 5 is the invention according to claim 4, wherein the motor relative angle information complementing unit detects a relative angular velocity, and the detected relative angular velocity is at least near zero. The offset amount and the period are determined so as to surely exceed the dead zone until the relative angle information is obtained by the motor relative angle calculation unit.

  An electric power steering apparatus according to a sixth aspect is the invention according to any one of the first to fifth aspects, wherein the motor relative angle calculation unit calculates the calculated relative angle information and an input for calculating the relative angle information. Relative angle calculation abnormality detecting means for detecting a relative angle calculation abnormality state for detecting at least one abnormality of the value, and when the relative angle calculation abnormality detection state is detected by the relative angle calculation abnormality detection means, an abnormality is detected. Relative angle information is calculated based on other input values that are not present.

The electric power steering apparatus according to a seventh aspect is the invention according to any one of the first to sixth aspects, wherein the motor relative angle calculation unit detects the rotation direction of the electric motor by the steering torque detecting means. It is characterized in that it is determined based on the steering torque.
Furthermore, in the electric power steering apparatus according to claim 8, in the invention according to any one of claims 1 to 7, the motor relative angle calculation unit increases an error of the calculated motor relative angle with respect to the actual angle. A correction state detection unit that detects that the correction state is required and a relative angle information correction unit that corrects the relative angle information when the correction state is detected by the correction state detection unit. It is said.

  Still further, according to a ninth aspect of the present invention, there is provided the electric power steering apparatus according to the second or third aspect, wherein the motor rotation angle detection means includes two sine wave and cosine wave rotation systems or other two or more different rotation angles. The motor rotation angle abnormality detecting means is configured to output a detection signal, and detects the motor rotation angle abnormality when the amplitude of one of the sine wave and the cosine wave is out of a predetermined range. The angle calculation unit includes a correction required state detection unit that detects that a correction required state in which an error with respect to the actual angle of the calculated motor relative angle is increased, and when the correction required state is detected by the correction required state detection unit, Relative angle information correcting means for correcting relative angle information, and the required correction state detecting means needs to be corrected when the amplitude of one of the normal sine wave and cosine wave reaches the maximum value and the minimum value. It detects that is, the relative angle correcting unit, when a main correction state, in actual angle at that time, is characterized in that it is configured to correct the relative angle information.

An electric power steering apparatus according to a tenth aspect is the invention according to the second or third aspect, wherein the motor rotation angle detecting means outputs two rotation angle detection signals of a sine wave and a cosine wave. The motor rotation angle abnormality detecting means detects a short of both waves by detecting whether or not the sum of the square value of the sine wave and the square value of the cosine wave is “1”, and the motor relative The angle calculation unit includes a correction required state detection unit that detects that a correction required state in which an error with respect to the actual angle of the calculated motor relative angle is increased, and when the correction required state is detected by the correction required state detection unit, Relative angle information correction means for correcting relative angle information is provided, and the required correction state detection means detects that the correction is required when the amplitudes of the shorted sine wave and cosine wave reach the minimum and maximum values. The relative angle information correcting unit, when a main correction state, in actual angle at that time, is characterized in that it is configured to correct the relative angle information.

  Furthermore, an electric power steering apparatus according to an eleventh aspect is the invention according to the second or third aspect, wherein the motor rotation angle detecting means includes a pole position sensor that outputs a multi-phase pole position signal, and the motor rotation The angle abnormality detection means detects an abnormality of one pole position sensor based on the pole position signal output from the pole position sensor, and the motor relative angle calculation unit has an error relative to the actual angle of the calculated motor relative angle. A required correction state detecting means for detecting an increase in the required correction state; and a relative angle information correcting means for correcting the relative angle information when the required correction state is detected by the required correction state detection means. The correction state detection means detects the correction required state when the pole position signal array uniquely determined out of 360 degrees according to the abnormal state of the pole position sensor, and detects the relative state. Degree information correcting unit, when a main correction state, the real angle of the corresponding pole position signal sequence is characterized in that it is configured to correct the relative angle information.

  According to the present invention, the relative angle information of the electric motor according to the steering amount of the driver calculates relative angle information such as the relative angular velocity and relative angle of the motor, and the relative angle information complementing unit calculates the driver's steering. Relative angle information is prevented from being obtained from the amount, and relative angle information can be output at all times, so the relative angle of the motor can be reliably detected with a simple configuration even when the initial actual motor angle is not fixed. The driving control of the electric motor by the motor control means can be continued to generate the steering assisting force according to the driver's intention, which does not increase the number of parts and increase the system cost. In addition, there is an effect that the steering assist control can be continued without giving the driver a sense of incongruity.

  At this time, when the relative angle of the motor enters a correction state in which the amount of error with respect to the actual angle may continue to increase, by correcting the relative angle information of the motor according to the state at that time, It is possible to reliably prevent the error from being enlarged.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram showing an embodiment of the present invention. In the figure, 1 is a battery mounted on a normal vehicle, and a battery voltage Vb output from the battery 1 is a fuse 2. Is input to the control device 3. The 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.

Here, 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 generating 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. A steering torque detection signal detected by the steering torque sensor 17 and a motor rotation angle detection signal detected by the resolver 18 are input to the control device 3.

Here, the steering torque sensor 17 detects the steering torque applied to the steering wheel 11 and transmitted to the steering shaft 12, and for example, a torsion bar in which the steering torque is inserted between an input shaft and an output shaft (not shown). The torsional angular displacement is converted into an electrical signal, and the torsional angular displacement is detected with a magnetic signal and converted into an electrical signal. As shown in FIG. 2, 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. 3, 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 to 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 also includes an FET gate drive circuit 22 that controls the field effect transistors FET1 to FET6 of the inverter circuit 21. The FET gate drive circuit 22 is configured to cause the field effect transistors FET1 to FET6 of the inverter circuit 21 to have duty ratios Da, Db, and Dc determined based on current command values Iat, Ibt, and Ict output from a microcomputer 30 described later. Are turned on / off by a PWM (pulse width modulation) signal, and the magnitudes of the currents Ia, Ib and Ic actually flowing in the electric motor 5 are controlled. Here, the FET1, FET3, and DFET5 that constitute the upper arm and the FET2, FET4, and FET6 that constitute the lower arm each have a dead time for avoiding an arm short according to the duty ratios Da, Db, and Dc. PWM drive.

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 includes phase current detection values Ia to Ic input from the current detection circuit 7 that detects each phase current of the electric motor 5 and terminal voltage detection that detects a terminal voltage of each phase of the electric motor 5. The phase terminal voltages Va to Vc inputted from the circuit 8 are inputted, the steering torque signal detected by the steering torque sensor 17 is inputted via the A / D conversion circuit 31, and the output signal of the resolver 18 is inputted. Motor rotation angle signals sin θ and cos θ from the motor rotation angle detection circuit 32 that outputs the motor rotation angle signal thus output. Is input to the input terminal, and the vehicle speed detection value Vs output from the vehicle speed sensor 33 that detects the vehicle speed Vs is input.

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.
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 time 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. 4, and a sudden change in the steering torque T input from the steering torque sensor 17 by a fail-safe signal SF from a fail-safe processing unit 49 to be described later. A gradual change control unit 41 that suppresses the gradual change, a steering torque Ts whose rapid change is restricted by the gradual change control unit 41, and a vehicle speed Vs detected by the vehicle speed sensor 33 are input, and an angular velocity to be described later A current command value calculation unit 42 that performs vector control based on the angular velocity ωe and the angular acceleration α input from the angular acceleration detection unit to calculate three-phase current command values Ia ^{* to} Ic ^* , and this current command value calculation current output be limited by the fail-safe signal SF from the fail-safe processing unit 49 to be described later current command value Ia ^* ~Ic ^* output from the section 42 A limited section 43 calculates a deviation ΔIa~ΔIc the phase current detection value Ia~Ic inputted from the current command value Ia ^* ~Ic ^* and current detection circuit 7 output from the current output limiting section 43 subtracts The subtractor 44 and the currents that output the command voltages Va ^{* to} Vc ^* to the FET gate drive circuit 22 of the motor drive circuit 6 by controlling the deviations ΔIa to ΔIc output from the subtractor 44 by, for example, proportional / integral (PI) control. The control unit 45, current detection values Ia to Ic input from the current detection circuit 7, and terminal voltages Va to Vc input from the terminal voltage detection circuit 8 are input. , The back electromotive force calculation unit 46 for calculating the line back electromotive voltages EMFab, EMFbc, and EMFCa generated by the motor, the sine wave signal (sinωt · sinθ) and the cosine input from the motor rotation angle detection circuit 32. A motor rotation angle calculation unit 47 that calculates a motor rotation angle θe represented by an electrical angle based on the signal (sin ωt · cos θ) and the peak detection pulse Pp, and a line back electromotive force calculated by the counter electromotive voltage calculation unit 46 Rotational angular velocity / angular acceleration calculation unit 48 as a relative angle and actual angle information detection unit that calculates angular velocity and angular acceleration based on the voltages EMFab, EMFbc, EMFCa and the motor rotation angle θe calculated by the motor rotation angle calculation unit 47. Then, the steering torque Ts detected by the steering torque sensor 17, the vehicle speed detection value Vs detected by the vehicle speed sensor 6, and the motor rotation angle θe calculated by the motor rotation angle calculation unit 47 are input, and the steering torque sensor 17 is based on these. , The vehicle speed sensor 33 and the resolver 18, the motor rotation angle detection circuit 32, and the motor rotation angle calculation unit 47 are detected to detect a failure and perform fail-safe processing. And a fail safe processing unit 49 as a motor rotation angle abnormality detecting means for performing.

Here, as shown in FIG. 5, the current command value calculation unit 42 is based on the steering torque Ts input from the steering torque sensor 17 and the vehicle speed detection value Vs, and the steering assist current command value I _M ^* shown in FIG. The steering assist torque command value calculation unit 42A that calculates the steering assist current command value I _M ^* with reference to the steering assist current command value calculation map for calculating the steering assist current command value I _M ^* , and the steering assist current calculated by the steering assist torque command value calculation unit 42A A command value compensation unit 42B for compensating the 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 later, and the command value compensation unit 42B compensated the command value I _M ^* . The dq-axis current command value calculating unit 42C calculates a dq-axis current command value based on the post-compensation torque command value I _M ^* 'and converts it to a three-phase current command value.

The steering assist torque command value calculation unit 42A calculates a steering assist torque command value I _M ^* that is a current command value with reference to the steering assist torque command value calculation map shown in FIG. 6 based on the steering torque Ts and the vehicle speed Vs. To do.
As shown in FIG. 6, the steering assist torque command value calculation map has a parabolic shape in which the horizontal axis represents the steering torque Ts, the vertical axis represents the steering assist torque command value I _M ^* , and the vehicle speed Vs is a parameter. 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 at least a SAT estimation feedback unit 53.

  Here, the convergence compensation unit 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 calculation unit 48, and the steering wheel in order 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 motion of 1 swinging.

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. 7 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. , An induced voltage model calculation for calculating a d-axis EMF component ed (θ) and a q-axis EMF component eq (θ) of a dq-axis induced voltage model EMF (Electro Magnetic Force) based on the motor rotation angle θ and the motor angular velocity ω. Unit 62, d-axis EMF component ed (θ) and q-axis EMF component eq (θ) output from this induced voltage model calculation unit 62, and d-axis target current Id ^* output from 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 q A two-phase / three-phase converter 64 that converts the q-axis target current Iq ^* output from the shaft target current calculator 63 into three-phase current command values Ia ^* , Ib ^*, and Ic ^* is provided.

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) where Ra, Rb, Rc are winding resistances of the motor, La, Lb, Lc are inductances of the motor, s is a Laplace operator, and here represents a differential operation (d / dt).

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.

  In the above formulas (6) to (8), the winding resistances Ra, Rb, Rc of the motor are fixed values. However, since the winding resistances Ra, Rb, Rc of the motor have temperature dependence, the motor temperature It is preferable to correct the motor winding resistances Ra, Rb, and Rc by detecting the motor, but when the motor winding resistances Ra, Rb, and Rc use fixed values as the motor winding resistances Ra, Rb, and Rc, and the motor resistance increases or decreases due to temperature fluctuations, etc. However, a fixed value may be adopted when back electromotive voltage / angle information of a level necessary for continuing the steering assist control is obtained. However, the winding resistances Ra, Rb, and Rc of the motor and the dead band setting value set in this case need to be set with a sufficient margin for temperature change in order to obtain angle information.

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.
Furthermore, as shown in FIG. 8, the angular velocity / angular acceleration calculation unit 48 includes a relative angular velocity calculation unit 48a that calculates the relative angular velocity ωee based on the counter electromotive voltage EMF input from the counter electromotive voltage calculation unit 46, and a steering wheel. A sign acquisition unit 48b that acquires a sign representing the rotation direction based on the steering torque Ts input from the torque sensor 17, and a multiplication that multiplies the relative angular velocity ωee calculated by the angular velocity calculation unit 48a by the code acquired by the code acquisition unit 48b. 48c, a rate limiter unit 48d for suppressing a rapid change in the relative angular velocity ωee output from the multiplication unit 48c, and an angular velocity region in which the relative angular velocity ωee for which the rapid change is suppressed by the rate limiter unit 48d is near zero. That is, it is determined whether or not it is within the dead zone of the neighborhood value ± Δω including ωe = 0, and ωee <−Δω or ωee> + Δω and is out of the dead zone. Sometimes the relative angular velocity ωee is output as it is, and when it is determined that ω−Δω ≦ ωee ≦ + Δω is in the dead zone, the relative angular velocity ωee is alternately set at predetermined intervals to a predetermined positive / negative relative angle information offset value ± Δωd. Is set so that the relative angular velocity ωee is a value other than “0”, and the relative angle information offset processing unit 48e as a relative angle information complementing unit, and the relative angular velocity ωee output from the relative angle information offset processing unit 48e. Is added to the previous motor rotation angle θe (n−1) to calculate the relative rotation angle θee, and the relative rotation angle θee output from the addition unit 48f and the motor rotation angle calculation unit 47 are input. An actual rotation angle θer to be selected based on the fail-safe signal SF, and a rotation angle selection unit 48g as a selection means for selecting the actual rotation angle θer and a motor rotation angle calculation unit 47. The angular velocity calculation unit 48h that differentiates the rotation angle θer to calculate the actual angular velocity ωer, the actual angular velocity ωer input from the angular velocity calculation unit 48h, and the relative angular velocity ωee output from the relative angle information offset processing unit 48e are fail-safe. An angular velocity selection unit 48i that is selected based on the signal SF and an angular acceleration calculation unit 48j that calculates the angular acceleration α by differentiating the angular velocity ωe selected by the angular velocity selection unit 48i. Here, the back electromotive force calculation unit 46, the angular velocity calculation unit 48a, the code acquisition unit 48b, and the multiplication unit 48c constitute a relative angle information calculation unit.

Here, the relative angular velocity calculation unit 48a calculates the relative angular velocity ωee by performing the calculation of the following equation (9) based on the counter electromotive voltage EMF input from the counter electromotive voltage calculation unit 46.
ωee = EMF / Ke (9)
Here, Ke is a back electromotive force constant [V / rpm] of the motor.
In addition, in the dead band setting unit (not shown) in the back electromotive voltage calculation unit 46, the winding resistances Ra to Rc of the motors of the equations (6) to (8) for calculating the line back electromotive voltages EMFab, EMFbc, and EMFCa described above. 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 ^* .

Furthermore, since it is also affected by the inductance due to the motor rotation speed change, it is preferable to remove the influence of the inductance fluctuation by feeding back the inductance fluctuation amount to the counter electromotive voltage calculation unit 46 according to the motor rotation speed.
Furthermore, the dead zone width ± Δω of the relative angle offset processing unit 48e is a set value that defines a region where the relative angle is 0 or in the vicinity thereof. Since the motor is driven at a relative angle, if the magnetic field restraint force between the stator and rotor of the motor is large within the range where the motor relative angular velocity is indicated by ± Δω, the driver next steers the steering wheel to obtain the relative angle information. (In this case, the back electromotive voltage) cannot be obtained, and so-called steering (handle) lock is obtained.

  Therefore, the relative angle offset value ± Δω is such that when the relative angular velocity is within the range indicated by ± Δω, the driver can steer the steering wheel, such as the binding force of the magnetic field and the torsion of the torsion bar, and rotate the motor. Therefore, it is necessary to set the value so as to surely remove the dead zone that occurs before the steering amount can be obtained. The relative angle offset value ± Δω for removing the dead zone is added to the relative angular velocity while inverting the sign at a predetermined period. Furthermore, it is necessary to keep the set value of ± Δω within an amount and a period in which steering assistance not intended by the driver is not performed. Here, the angle amount to be positively and negatively offset must be the same value in order to prevent the angle from continuing to shift in an unintended direction.

  Furthermore, 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 adder 48f 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”. Is selected, the relative angular velocity ωee input from the relative angle information offset processing unit 48e is selected.

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. 10, 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.

The process of FIG. 9 corresponds to the motor rotation angle abnormality detection means.
Then, the microcomputer 30 executes a steering assist control process shown in FIG. 11 corresponding to the command value calculation unit 42 based on each input signal.
As shown in FIG. 11, in the steering assist control process, first, in step S1, detection values of various sensors such as the steering torque sensor 17 and the vehicle speed sensor 33, the rotation angle θe calculated by the angular velocity / angular acceleration calculation unit 48, and the angular velocity are calculated. Then, ωe and angular acceleration α are read, and then the process proceeds to step S2, and the steering assist torque command value I _M ^* is calculated based on the steering torque T with reference to the steering assist torque command value calculation map shown in FIG. Then, the process proceeds to step S3.

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

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 voltage, and the process proceeds to step S11 to output the calculated voltage command values Vu ^{* to} Vw ^* 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.

The microcomputer 30 corresponds to the relative angular velocity calculation unit 48a, the sign acquisition unit 48b, the multiplication unit 48c, the rate limiter unit 48d, and the relative angle information offset processing unit 48e of the angular velocity / angular acceleration calculation unit 48 shown in FIG. Execute angular velocity calculation processing.
This relative angular velocity calculation process is executed as a timer interrupt process at predetermined time intervals (for example, 1 msec). First, in step S31, the counter electromotive voltage EMF calculated by the counter electromotive voltage calculation unit 46 is read, and then the process proceeds to step S32. Then, based on the back electromotive force EMF, the calculation of the above-described equation (9) is performed to calculate the relative angular velocity ωee, and then the process proceeds to step S33 where the sign of the steering torque Ts is acquired and added to the relative angular velocity ωee. Then, the process proceeds to step S34.

  In this step S34, the change amount Δωee is calculated by subtracting the previously calculated relative angular velocity ωee (n-1) from the calculated current relative angular velocity ωee (n), and then the process proceeds to step S35, where the calculated change amount is calculated. It is determined whether or not the absolute value of Δωee exceeds a preset change amount upper limit value Δωs. If | Δωee | ≦ Δωs, it is determined that the change amount Δωee is small, and the process proceeds to step S39 described later. When ωee |> Δωs, it is determined that the change amount Δωee is too large, and the process proceeds to step S36.

  In this step S36, it is determined whether or not the change amount Δωee is a positive value or zero. If Δωee ≧ 0, the process proceeds to step S37, where the change amount upper limit value Δωs is added to the previous relative angular velocity ωee (n−1). Is added to calculate the current relative angular velocity ωee (n), and then the process proceeds to step S39. If Δωee <0, the process proceeds to step S38, and the upper limit of change from the previous relative angular speed ωee (n-1). After subtracting the value Δωs to calculate the current relative angular velocity ωee (n), the process proceeds to step S39.

In step S39, it is determined whether or not the relative angular velocity ωee calculated in step S33 and the current relative angular velocity ωee (n) calculated in step S37 or S38 are within the dead zone defined by ± Δω. When −Δω ≦ ωee ≦ + Δω and within the dead zone, the process proceeds to step S40.
In this step S40, the relative angle information offset value Δωd set to a value at which the angle change with respect to the motor relative rotation angle θee becomes, for example, ± 2 deg per addition cycle is set as the current relative angular velocity ωee, and then the process proceeds to step S41. Then, "1" is added to the current time coefficient value t to calculate a new time coefficient value t, and then the process proceeds to step S42, where the time coefficient value t exceeds a predetermined value ts (e.g., equivalent to 20 msec) If t> ts, the process proceeds to step S43, the current relative angle information offset value Δωd is multiplied by − to invert the sign, and then the process proceeds to step S44.

In step S44, the time coefficient value t is cleared to "0", the timer interrupt process is terminated, and the process returns to the predetermined main program.
Further, when the determination result of step S39 is ωee <−Δω or ωee> + Δω, it is determined that it is outside the dead zone, and the timer interruption is ended as it is, and the determination result of step S42 is t ≦ ts. Sometimes, the timer interrupt process is terminated as it is, and the process returns to a predetermined main program.

In the processing of FIG. 12, the processing of steps S31 to S38 corresponds to the motor relative angle information calculation unit, and the processing of steps S39 to S44 corresponds to the relative angle information complementing unit.
Next, the operation of the first embodiment will be described.
Now, by turning on the ignition switch 37 shown in FIG. 3, 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 motor rotation angle abnormality shown in FIG. The process, the steering assist control process shown in FIG. 11, the relative angular velocity calculation process shown in FIG.

In this state, in the steering assist control process of FIG. 11 executed by the microcomputer 30, the steering torque detection value T detected by the steering torque sensor 17 is read (step S1), and then neutralized from the read steering torque detection value T. by subtracting the torque T ₀ to calculate the steering torque Ts shown in (step S2), and then reads the vehicle speed detection value Vs from the vehicle speed sensor 33 (step S3), and 6 based on the steering torque Ts and the vehicle speed detection value Vs The steering assist command value I _M ^* is calculated with reference to the steering assist command value calculation map (step S4).

  At this time, assuming that the resolver 18, the motor rotation angle detection circuit 32, and the A / D converters 35 and 36 are normal, when the motor rotation angle abnormality detection process of FIG. 9 is executed, the motor rotation shown in FIG. The angle calculation unit 47 reads sin θ and cos θ calculated based on 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 and the peak detection pulse Pp (step S21). By referring to the abnormality determination map shown in FIG. 10 based on the read sin θ and cos θ, the points represented by sin θ and cos θ are within the normal region shown by the oblique lines, so that it is determined to be normal and the logical value A fail safe signal SF of “0” is output to the angular velocity / angular acceleration calculator 48. (Step S23).

  For this reason, in the angular velocity / angular acceleration calculation unit 48 shown in FIG. 8, 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 actual angular velocity ωer obtained by differentiating the actual rotation angle θer is selected by the angular velocity calculating unit 48h in the selection unit 48i, and this is set as the angular velocity ωe. Further, the angular acceleration calculating unit 48j differentiates the angular velocity ωe to calculate the angular acceleration α, The rotation angle θe, the angular velocity ωe, and the angular acceleration α are output to the current command value calculation unit 42.

Therefore, in the steering assist control process of FIG. 11 executed by the current command value calculation unit 42, the process proceeds from step S2 to step S3, the convergence compensation value Ic is calculated based on the angular velocity ωe, and then the motor angular acceleration α is calculated. Based on this, the inertia compensation value I _i for inertia compensation control is calculated (step S4), and further, the self-aligning torque SAT is calculated based on the angular velocity ωe, the angular acceleration α, the steering torque Ts, and the steering assist torque command value I _M ^*. (Step S5).

Then, the steering assist torque command value I _M ^* to convergence compensating value Ic, by adding the inertia compensation value Ii and the self aligning torque SAT is calculated compensated steering assist torque command value I _M ^* '(step S6), and Based on the calculated post-compensation steering assist torque command value I _M ^* ′, the rotation angle θe and the angular velocity ωe, the dq axis command value calculation process is executed, and the target d axis current Id ^* and the target q axis current Iq ^* are obtained. The target d-axis current Id ^* and the target q-axis current Iq ^* are subjected to a two-phase / three-phase conversion process to calculate three-phase motor current command values Ia ^* , Ib ^* and Ic ^* (step S7). Step S8).

Then, current feedback processing is performed based on the calculated target phase current values Ia ^* , Ib ^* and Ic ^* and the detected motor phase currents Ia, Ib and Ic, and the voltage command values Va ^* , Vb ^* and Vc ^* are calculated (step S10), and these phase voltage command values Va ^* , Vb ^* and Vc ^* are output to the FET gate drive circuit 22 of the motor drive circuit 6 (step S11).

  For this reason, the FET gate drive circuit 22 supplies the three-phase drive current from the motor drive circuit 6 to the electric motor 5 by controlling the pulse width modulation of the field effect transistors Qua to Qwb of the motor drive circuit 6, and this electric drive The motor 5 generates a steering assist force in a direction corresponding to the steering torque applied to the steering wheel 11, and transmits this 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. 6 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.
In the normal steering state in which the vehicle is started from the stopped state to the traveling state and the steering wheel 11 is steered in this state, the steering assist torque that is required decreases as the vehicle speed increases. The steering torque transmitted to is also a small value, which is detected by the steering torque sensor 17 and input to the microcomputer 30. For this reason, the steering assist command value I _M ^* is also a small value, and the steering assist torque generated by the electric motor 5 is smaller than the steering assist torque at the time of stationary.

  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 in the processing becomes abnormal and the motor abnormality detection processing in FIG. 9 refers to the abnormality determination map shown in FIG. 10 based on sin θ and cos θ, it is expressed as sin θ and cos θ. The point that is out of the normal area shown by the hatched lines is immediately, and the fail-safe signal SF having the logical value “1” immediately becomes the angular velocity. It is output to the angular acceleration calculating unit 48.

  Therefore, in the angular velocity / angular acceleration calculation unit 48, the rotation angle selection unit 48g selects the relative rotation angle θee calculated by the addition unit 48f, and the angular velocity selection unit 48i calculates the relative angle information offset processing unit 48e. Relative angular velocity ωee is selected. At this time, as the initial value of the relative rotation angle θee, the previous rotation angle θer (n−1) in which the resolver 18 and the like were normal is supplied to the adding unit 48f.

In this way, when the rotation angle selection unit 48g and the angular velocity selection unit 48i are switched, the relative (rotation) angle calculation process based on the back electromotive force EMF is performed by the relative rotation angle calculation process of FIG. A rotation angle θe, an angular velocity ωe, and an angular acceleration α are determined.
At this time, the back electromotive force calculation unit 46 calculates the line voltages Vab, Vbc, and Vca by performing the calculations of the above-described formulas (3) to (5), and then the formulas (6) to (8). By performing the calculation, the line back electromotive voltages EMFab, EMFbc, and EMFCa are calculated, and these are added to calculate the back electromotive voltage EMF.

Then, in the relative rotation angle calculation process, the calculated back electromotive voltage EMF is read (step S31), and then the calculation of the equation (9) is performed based on the back electromotive voltage EMF to calculate the relative angular velocity ωee (step). S32).
Next, the current relative angular velocity ωee (n) having a sign corresponding to the rotation direction of the electric motor 5 is calculated by adding the sign of the steering torque Ts detected by the steering torque sensor 17 to the calculated relative angular speed ωee. .

  Then, the change amount Δωee is calculated by subtracting the previous relative angular velocity ωee (n−1) from the calculated current relative angular velocity ωee (n) (step S34), and the absolute value of the change amount Δωee is the upper limit of the change amount. When the value is equal to or smaller than the value Δωs, the relative angular velocity ωee (n) is set as the current value as it is. However, when the absolute value of the change amount Δωee exceeds the change amount upper limit value Δωs, it is determined that the change amount is too large. The change amount upper limit value Δωs is added to or subtracted from the angular velocity ωee (n−1) to limit the change amount of the relative angular velocity ωee.

When the calculated relative angular velocity ωee (n) is outside the dead zone, the relative angular velocity ωee (n) is determined and supplied to the adding unit 48f and the angular velocity selecting unit 48i.
For this reason, the adding unit 48f calculates the relative rotation angle θee by adding the relative angular velocity ωee to the previous rotation angle θer (n−1).
The calculated relative rotation angle θee is selected by the rotation angle selection unit 48g and output to the current command value calculation unit 42 as the rotation angle θe, and the relative angular velocity ωee (n) is selected by the angular velocity selection unit 48i and the angular velocity. The angular velocity α is calculated by differentiating the angular velocity ωe by the angular acceleration calculating unit 48j, and the angular acceleration α is also output to the current command value calculating unit 42.

  For this reason, the current command value calculation unit 42 replaces the actual rotation angle θer, the actual angular velocity ωer based on the actual rotation angle θer, and the angular acceleration α based on the abnormal steering rotation control process of FIG. The relative angular velocity ωee and the relative angular acceleration α are applied, the command value compensation processing and the dq axis command value calculation processing based on the relative angular velocity information are executed, and the steering assist control processing is continued.

As described above, when the relative rotation angle θee and the relative angular velocity ωee are selected by the angular velocity / angular acceleration calculation unit 48, the relative angular velocity ωee calculated by the angular velocity calculation unit 48a is in the vicinity of zero −Δω ≦ ωee ≦ + Δω. Thus, when the dead zone is reached, the process proceeds from step S39 to step S40 in FIG. 12, and the relative angular velocity ωee is subjected to the relative angle offset process.
That is, within the dead zone, every time a predetermined time (for example, 20 msec) is reached, the relative angular information offset value ± is set such that the angular change with respect to the motor relative rotational angle θee becomes ± 2 deg per addition cycle as the relative angular velocity ωee. By repeatedly setting Δωd, the relative angular velocity ωee is repeatedly set to a value other than “0”.

  Thus, when the relative angular velocity ωee is within the dead zone, ± Δωd is set as the relative angular velocity ωee, and it is possible to reliably prevent the relative angular velocity ωee from becoming “0”. Then, the relative angular velocity ωee set to the relative angle information offset value ± Δωd is added to the previous rotation angle θee (n−1) by the adding unit 48f, so that the relative rotation angle θee becomes the previous rotation angle θee (n -1), the angle changes by ± 2 deg corresponding to the relative angle information offset value ± Δωd of the relative angular velocity ωee.

  That is, when the relative angular velocity ωee is in an angular velocity region near “0” in a state where the angle information cannot be used and, for example, a high steering assist force is generated by the electric motor 5, the driver steers the steering wheel 11. In some cases, the limit of rotating the electric motor 5 may be exceeded, leading to a so-called steering (steering) lock, so the dead zone until the driver steers the steering wheel to obtain a back electromotive voltage next time. By alternately setting the relative angle information offset value ± Δωd that changes the angle information so that the angle information exceeds ±, the relative angular velocity ωee is surely prevented from being “0” and the occurrence of steering lock is reliably prevented. However, the steering assist control process based on the relative angular velocity ωee can be continued.

  Moreover, when the relative angular velocity ωee is calculated based on the back electromotive force EMF of the electric motor 5, it is difficult to grasp the rotation direction of the electric motor 5, and for example, phase commutation or reverse of the current supplied to the electric motor 5 is performed. Although the motor rotation direction may be determined according to the appearance of the electromotive voltage, there is still a possibility of generating a steering assist force against the driver's will, so the driver's intention as in the first embodiment described above remains. By determining with the direction of the steering torque Ts representing the direct will, the rotation direction according to the driver's will can be set.

The principle that the electric motor 5 can be rotationally driven based on the relative rotation angle θee is as follows.
That is, the relationship between the magnetic field vector relative angle error between the rotor and stator of the brushless motor and the absolute value of the energy generated in the rotor is as shown in FIG.
Here, if a fixed current is passed through the stator without considering the rotor position, the motor rotates by generating torque until the magnetic field vectors of the rotor and the stator coincide as shown in “State 1” in FIG. To do.

  As shown in “state 2”, when the magnetic field vectors of the rotor and the stator coincide with each other, the rotor is restrained by the magnetic field of the stator and does not move (motor torque = 0 Nm). That is, a complete energization state for the d-axis is obtained. In this “state 2”, when the phase current is changed in accordance with the direction in which the motor is to be rotated and the rotational speed, the rotor rotates while being constrained by the magnetic field of the stator. The binding force at this time is proportional to the phase current.

  As described above, in the first embodiment, when an abnormality occurs in the rotation angle detection system that detects the rotation angle of the electric motor 5, the relative angular velocity ωee is calculated based on the counter electromotive voltage EMF. The steering assist control can be continued by calculating the relative rotation angle θee and the relative angular acceleration α according to the steering amount with respect to the steering system of the person, but considering the safety, the rotation angle detection system When an abnormality occurs, it is preferable to continue the steering assist control by reducing the sensitivity of the steering assist control.

In this case, in the functional block diagram of FIG. 4 described above, the gradual change control unit 41 and the current output limiting unit 43 are provided before and after the current command value calculating unit 42, and the gradual change control unit 41 and the current output limiting unit 43 are provided. When the fail safe signal SF input from the fail safe processing unit 49 is a logical value “0”, the gradual change function and the limiting function are stopped, and when the logical value is “1”, the gradual change function and the limiting function are exhibited. Thus, it is preferable to limit the current command values Ia ^{* to} Ic ^* to reduce the steering assist force generated by the electric motor 5.

  Further, the command value compensator 42B reacts unnecessarily when the relative rotational angle θee based on the relative angular velocity ωee based on the back electromotive force is used, even if necessary when the rotational angle detection system is normal. For the compensation unit, the output is set to “0” or multiplied by a gain of “1” or less, so that the effect of the compensation unit is reduced by making the value smaller than that in the normal state. It is preferable that a necessary compensation unit is configured to employ a compensation value larger than usual.

  Specifically, compensation control based on angle information (compensation based on the position of the motor) should be stopped, but has the effect of reducing the error of the actual angle relative to the relative angle, Compensation control that has the effect of reducing the error between the relative angle and the actual angle by making the gain smaller or larger than normal should be performed. In other words, compensation control that can be an element that increases the error between the relative angle and the actual angle should be stopped.

  Furthermore, in the first embodiment, the line back electromotive voltages EMFab to EMFCa are calculated based on the line voltages Vab to Vca, and these are added to calculate the motor back electromotive voltage EMF. The relative angular velocity ωee can be calculated from the back electromotive voltage without depending on the connection of the electric motor 5, that is, the Y connection or the Δ connection, and the back electromotive voltage can be detected without providing a separate detection circuit or the like. There is.

  In the first embodiment, the back electromotive voltage EMF is calculated from the line voltages Vac to Vca according to the equations (6) to (8), and the line back electromotive voltages EMFab to EMFCa are added. However, the present invention is not limited to this. When a Y-connection motor is applied as the electric motor 5, the midpoint voltage of the electric motor is detected, and this midpoint voltage is set for each motor. The phase voltage Vih (i = a to c) is calculated by subtracting from the terminal voltages Va to Vc, and the back electromotive force ei of each phase is calculated by performing the following equation (10) based on the phase voltage Vih. The relative angular velocity ωee may be calculated by performing the following calculation (11) based on the calculated back electromotive voltages ea to ec. In this case, the amount of error between the relative angular velocity ωee and the actual angle can be reduced without increasing the calculation load, the rotation angle detection system is omitted, and an accurate steering assist control process is performed based on the relative angular velocity ωee. Can be executed.

ei = Vih− (Ri + s · Li) · Ii (10)
ωee = 2 × {max (| ea |, | eb |, | ec |)} / Ke (11)
In this case, instead of detecting the midpoint voltage, the midpoint voltage is ½ of the motor drive circuit applied voltage. Therefore, the value of the motor drive circuit applied voltage ½ is the midpoint voltage Vn and the phase voltage. Vah to Vch may be calculated.

Further, the sum of the motor terminal voltages of the electric motor 5 is obtained as in the following equation (12), and each phase voltage is calculated with the value obtained by dividing the sum by the number of phases of the motor as the motor midpoint voltage Vn. May be.
Vn = (Va + Vb + Vc +... + Vx) / number of motor phases) (12)
When calculating the back electromotive force ei, instead of the above equation (10), as shown in the following equation (13), the voltage command value Vi ^* (i = a to c) output from the current control unit 45. ) Based on the duty ratio Di, the battery voltage Vbat, and the motor current Ii calculated by the FET gate drive circuit 22, the counter electromotive voltage ei may be calculated.

ei = Di · Vbat− (Ri + s · Li) · Ii (13)
In this case, since the counter electromotive voltage ei can be calculated without using the motor terminal voltages Va to Vc, the counter electromotive voltage calculation unit that calculates the counter electromotive voltage ei based on the above equation (13) is described above. By providing in place of the counter electromotive voltage calculation unit 46, the motor terminal voltage detection unit 8 can be omitted, and the configuration of the control device 3 can be simplified accordingly.

Further, by providing a counter electromotive voltage calculation unit for calculating the counter electromotive voltage ei based on the above equation (13) in parallel with the counter electromotive voltage calculation unit 46, the counter electromotive voltage calculation unit 46 calculates the counter electromotive voltage ei. When an abnormal state that cannot be performed occurs, it is possible to perform an alternative calculation of the back electromotive voltage ei.
In the first embodiment, the case where the relative angle information offset processing is performed when the relative angular velocity ωee calculated by the relative angular velocity calculating unit 48a is within the dead zone has been described. However, the present invention is not limited to this. The relative angle information offset process may always be performed regardless of whether or not the relative angular velocity ωee is within the dead zone. Further, in this case, the relative angle information offset value may be reduced when outside the dead zone, and the relative angle information offset value may be increased when inside the dead zone.

  Furthermore, the relative angle information offset value is not limited to a value corresponding to ± 2 deg, and may be set so as to exceed the dead zone from the time when the speed becomes 0 until the next steering. However, since the electric motor 5 can generate vibrations by increasing the relative angle information offset value, increasing the addition period, or both, the driver can operate when the rotation angle detection system is abnormal. In order to notify the abnormality and notify the repair required state, a large relative angle information offset value may be set and / or the addition period may be increased to give vibration to the steering wheel 11. .

  In this case, the vibration may be increased stepwise within the range of the maximum value as time elapses from the occurrence of the abnormality. Furthermore, since it is possible to generate a control sound from the electric motor by always performing the relative angle information offset process, it is necessary to change the relative angle information offset value and the addition cycle to a level that can be used as an abnormality occurrence notification. It can also be employed as a means for notifying the repair status.

In the first embodiment, the case where the relative angle information offset value ± Δωd is set to the relative angular velocity ωee has been described. However, the present invention is not limited to this, and the motor is calculated based on the relative angular velocity ωee. A relative angle information offset value corresponding to the relative angle information offset value ± Δωd may be added to or subtracted from the rotation angle θee.
Furthermore, in the first embodiment, the case where the relative angular velocity ωee is set to the relative angle information offset value ± Δωd in the dead zone from the zero velocity region has been described, but the present invention is not limited to this. For example, by adopting resistance model values instead of actual resistance values as winding resistances Ra to Rc set by a dead zone setting unit (not shown) in the back electromotive force calculation unit 46, errors in the relative angular velocity ωee are eliminated. It is also possible to set a value corresponding to the relative angle information offset value ± Δωd by intentionally making the dead band width to be small intentionally and intentionally using information that is ignored as angle information in the control.

  Furthermore, in the first embodiment, the case where the rotation direction is given based on the steering torque has been described. However, the present invention is not limited to this. If it can be maintained, for example, it is desirable to give the direction by judging the rotation direction from two or more different information sources such as the steering rotation direction information from the rudder angle sensor and the phase commutation status and the appearance of the back electromotive force. .

Still further, in the first embodiment, the relative angular velocity ωee is calculated based on the back electromotive force EMF, and this relative angular velocity ωee is added to the previous motor rotational angle θee (n−1) to thereby calculate the motor rotational angle. Although the case where θee is calculated has been described, the line back electromotive voltages EMFab, EMFbc, and EMFCa are sinusoidal waves. Therefore, the zero cross point of the line back electromotive voltages EMFab, EMFbc, and EMFCa is detected, and the zero cross point is determined. By correcting the motor rotation angle θee with the motor rotation angle (electrical angle) uniquely determined at the time of detection as shown in Table 1 below, a more accurate motor rotation angle θee can be calculated.

  In the first embodiment, the case has been described in which the previous relative rotation angle θer (n−1) in which the resolver 18 or the like is normal is supplied to the adding unit 48f as the initial value of the relative rotation angle θee. However, the present invention is not limited to this, and the motor can be reliably driven based on the relative angle as described above. Therefore, an arbitrary rotation angle θer can be set as the initial value. For this reason, the relative angle is not calculated until the motor rotation angle is determined to be abnormal, and the calculation of the relative angle starts when the motor rotation angle is determined to be abnormal or when a sign of abnormality is detected. The motor may be driven based on the relative angle. In this case, the processing load of the arithmetic processing device can be reduced.

  Furthermore, in the first embodiment, the case where the relative speed ωee as the relative angle information is calculated based on the back electromotive force EMF has been described. However, the present invention is not limited to this and is obtained from the steering angle sensor. The relative speed ωee may be calculated based on the amount of change in the steering angle, and in the case of a double failure state in which the back electromotive voltage cannot be obtained, the steering amount obtained from the steering angle sensor is calculated. The relative angle θee may be directly calculated by switching.

Next, a second embodiment of the present invention will be described with reference to FIGS.
In this second embodiment, when the relative angular velocity ωee is in the “0” angular velocity region, the relative angle information offset process is performed, and the relative angle is complemented based on the steering torque Ts. A complementary relative angle information calculation unit for calculating the angular velocity ωee ′ is provided.

  That is, in the second embodiment, as shown in FIG. 14, a complementary relative angle information calculation unit 70 that calculates the complementary relative rotation angle θee ′ based on the steering torque Ts detected by the steering torque sensor 17 is provided. The same configuration as that of the first embodiment described above except that the complementary relative rotation angle θee ′ calculated by the complementary relative angle information calculating unit 70 is supplied to the angular velocity / angular acceleration calculating unit 48. Have

Here, the complementary relative angle information calculation unit 70 executes the complementary relative angle calculation process shown in FIG. This complementary relative angle calculation process is executed as a timer interrupt process at predetermined time intervals (for example, 1 msec). First, in step S51, the steering torque Ts calculated in the steering assist control process is read, and then the process proceeds to step S52. To do.
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 step S52 is a dead zone in the preset steering assist control, that is, a mechanical dead zone such as a reduction gear efficiency, a rack and pinion efficiency, etc. of the electric power steering mechanism. It is determined whether or not it is within the dead zone in the electric power steering mechanism obtained by the setting including, and if within the dead zone, the process proceeds to step S54, the steering torque average value Ts _M is changed to “0”, and then step S55. If it is outside the dead zone, the process proceeds to step S55 as it is.

In step S55, the steering torque average at the calculated steering torque average value Ts _M or steering torque average value Ts _M in becomes the current steering torque average value Ts _M (n) and the previous sampling changed in step S54 in step S52 It is determined whether or not the change amount ΔT with respect to the value Ts _M (n−1) exceeds a preset upper limit value ΔTu. If ΔT> ΔTu, it is determined that the change amount ΔT is too large, and the process proceeds to step S56. The 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 it is, it is determined that the change amount ΔT is within the allowable range, and the process directly proceeds to step S57.

The processes in steps S55 and S56 are limiter processes that limit the change amount ΔT. In this case, the upper limit value ΔTu may be a predetermined value or an optimum value according to the vehicle speed Vs.
In step S57, the calculation of the following equation (13) 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 (13)
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 this step S59, the motor relative angle θ _MP (n) is converted into, for example, a 12-bit electrical angle 0 to 4096, stored in a predetermined storage area of the RAM built in the microcomputer 30, and the timer interrupt process is terminated. .
The processing of FIG. 15 and the selection unit 48n of the angular velocity / angular acceleration calculation unit 48 correspond to a relative angle information complementing unit.

Then, the complementary relative angle calculation process of FIG. 15 is configured as shown in FIG. 16 in a functional block diagram.
The motor relative angle information calculation gain Km may be a constant value, but may be changed according to the vehicle speed Vs. For this purpose, a motor advance angle such as a gain for calculating the motor relative angle information based on the vehicle speed Vs. It is also possible to provide parameter setting means for changing a parameter that can be adjusted.

  In addition, when the electric motor 5 or the control device 3 is overheated, it is fixed when the temperature increase beyond that is suppressed by reducing the energization amount to the electric motor 5 or when the vehicle speed sensor 33 becomes abnormal. In the case of continuing the steering assist control by setting the vehicle speed, for example, the inclination of the steering assist command value calculation map of FIG. 5 becomes smaller as the vehicle speed becomes faster, so that the vehicle speed range slower than the fixed vehicle speed. When the output of the steering assist force in the steering assist control process is limited, as in the case where the steering assist force is limited to a small value, the relative angle information calculation gain Km is also set in accordance with the output limit amount. It is desirable to change to adjust the advance angle. For this reason, a second parameter setting means for changing a parameter capable of adjusting a motor advance angle such as a gain for complementary relative angle information calculation according to the output limit amount in the output limit state of the steering assist force is provided. Also good.

  Then, the angular velocity / acceleration calculating unit 48 is changed as shown in FIG. That is, the relative angle information offset processing unit 48e of the angular velocity / angular acceleration calculation unit 48 is omitted, and instead, the relative angular velocity ωee limited by the rate limiter unit 48d is directly supplied to the addition unit 48f and the dead zone detection unit 48m is supplied. And the output of the adder 48f is supplied to one input side of the second rotation angle selector 48n switched by the detection signal of the dead zone detector 48m, and the other input side of the second rotation angle selector 48n Is supplied with the relative rotation angle θee ′ calculated by the complementary relative angle information calculation unit 70, and the relative rotation angle θee selected by the second rotation angle selection unit 48n is supplied to one input side of the rotation angle selection unit 48g. The relative angular velocity supplied and further limited by the rate limiter unit 48d is supplied to one input side of the second angular velocity selecting unit 48p, and the second angular velocity selecting unit 48 is supplied. Except that the output of the angular velocity calculation unit 48o for differentiating the relative rotation angle ωee ′ calculated by the complementary relative angle information calculation unit 70 to calculate the complementary angular velocity ωee ′ is supplied to the other input side. Has the same configuration as in FIG. Here, in the dead zone detection unit 48m, when the relative angular velocity ωee is outside the dead zone, the detection signal SD having the logical value “0” is output to the second rotation. Output to the angle selector 48n and the second angular velocity selector 48o. In the second rotation angle selector 48n, when the detection signal SD is a logical value “0”, the relative rotation angle θee output from the adder 48f. When the logical value is “1”, the complementary relative rotation angle θee ′ calculated by the complementary relative angle information calculating unit 70 is selected. In the second angular velocity selecting unit 48o, the detection signal SD is the logical value “ When the value is “0”, the relative angular velocity ωee limited by the rate limiter unit 48d is selected. When the value is “1”, the complementary relative angular velocity ωee ′ calculated by the angular velocity calculation unit 48o is selected. .

Next, the operation of the second embodiment will be described.
First, the complementary relative angle information calculation unit 70 executes the complementary relative angle calculation process of FIG. 15, reads the steering torque Ts every predetermined time by the timer interrupt process, and then reads the steering torque Ts read this time. The steering torque average value Ts _M (n) is calculated by averaging the past predetermined number of steering torques Ts (n) to Ts (n-31) including (step S52). By performing this averaging process, the number LSB flutter generated when the steering torque T output from the steering torque sensor 17 is converted into a digital signal by the A / D converter 31 is used as a noise component. It can be surely prevented.

Then, it is determined whether or not the calculated steering torque average value Ts _M (n) is within the dead zone (step S53). If it is within the dead zone, the steering torque average value Ts _M (n) is set to “0”. (Step S54), it is possible to reliably prevent the electric motor 5 from being inadvertently driven to rotate when the driver does not intend.
On the other hand, when the steering torque average value Ts _M (n) is outside the dead zone, the process directly proceeds to step S55.

Then, a change amount ΔT of the calculated steering torque average value Ts _M (n) with the steering torque average value Ts _M (n−1) at the previous sampling is calculated, and the calculated change amount ΔT is a preset upper limit value. It is determined whether or not ΔTu is exceeded. When ΔT> ΔTu, it is determined that the amount of change is too large, and a value obtained by adding the upper limit value ΔTu to the steering torque average value Ts _M (n−1) at the previous sampling. Is set as the current steering torque average value Ts _M (n) (step S56), and when ΔT ≦ ΔTu, the steering torque average value Ts _M (n) is used as it is. When the amount of change in the steering torque average value Ts _M (n) is large by the processing in steps S55 and S56, the amount of change is limited to the upper limit value ΔTu, so that the relative rotation angle for complementation when the steering torque T suddenly rises. A sudden change in θ _MP can be limited.

Then, by adding the set relative rotational angle change amount Δθ _M to the complementary relative rotational angle θ _MP (n−1) at the previous sampling, the current complementary relative rotational angle θ _MP is calculated, and this is calculated. Is converted into a 12-bit electrical angle (0 to 4096) and updated and stored in a predetermined storage area of a RAM built in the microcomputer 30.
For this reason, when the motor rotation angle detection system is normal in the angular velocity / acceleration calculation unit 48 of FIG. 17, the motor rotation angle calculation unit 48g uses the rotation angle selection unit 48g as in the first embodiment described above. 47, the actual rotational angle θer calculated by 47 is selected, the angular velocity selecting unit 48i selects the actual angular velocity ωer calculated by the angular velocity calculating unit 48h, and the selected actual angular velocity ωer is differentiated by the angular acceleration calculating unit 48j. By calculating the angular acceleration α, and supplying the actual rotation angle θer, the actual angular velocity ωer, and the angular acceleration α to the current command value calculation unit 42, accurate phase target currents Ia ^{* to} Ic ^* are calculated based on these, Deviations ΔIa to ΔIc between the phase target currents Ia ^{* to} Ic ^* and the detected current values Ia to Ic are calculated, and these deviations ΔIa to ΔIc are subjected to PI control processing to calculate voltage command values Va ^{* to} Vc ^*. Voltage finger By outputting the command values Va ^{* to} Vc ^* to the FET gate drive circuit 22 of the motor drive circuit 6, a three-phase drive current is supplied to the electric motor 5 to generate a steering assist force.

When the fail safe processor 49 detects that an abnormality has occurred in the rotation angle detection system including the resolver 18, the fail safe signal SF having a logical value “1” is output from the fail safe processor 49 to the rotation angle selector 48g and It is output to the angular velocity selection unit 48i. As a result, the relative angular velocity ωee based on the back electromotive force EMF is selected as in the first embodiment described above.
When the calculated relative angular velocity ωee is outside the dead zone, the dead zone detector 48m outputs a dead zone detection signal SD having a logical value of “0” to the second rotation angle selector 48m and the second angular velocity selector 48p. The second rotation angle selection unit 48n selects the relative rotation angle θee calculated by the addition unit 48f, and the second angular velocity selection unit 48p selects the relative angular velocity ωee output from the rate limiter unit 48d. The current command calculation unit 42 calculates the three-phase current command values Ia ^{* to} Ic ^* based on the relative rotation angle θee, the relative angular velocity ωee, and the relative angular acceleration α calculated based on the back electromotive voltage EMF, and the electric motor 5 Is controlled and the steering assist force is generated from the electric motor 5, whereby the steering assist control process is continued.

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 having the logical value “1” is output from the dead band detecting unit 48m to the second rotation angle selecting unit. 48m and output to the second angular velocity selection unit 48p, the second relative rotation angle selection unit 48m calculates the complementary relative angle information calculation unit 70 and stores it in the RAM of the microcomputer 30. The rotation angle θ _MP is selected, and 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 by the second angular velocity selection unit 48p.

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. The complementary relative rotation angle θ _MP and the relative angular velocity ωee ′ formed by the differential value thereof are selected, and the relative angular acceleration α obtained by differentiating the complementary relative angular velocity ωee ′ is output to the command value calculation unit 42, whereby As in the first embodiment, the steering assist control process is 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 steering (handle) lock. Can do.

  In the second embodiment, the case where the complementary relative angular velocity ωee ′ calculated based on the steering torque Ts is selected when the relative angular velocity ωee is in the dead zone has been described. However, the present invention is not limited to this. If the steering torque Ts when the relative angular velocity ωee is in the dead zone is large, the relative angle θee may change suddenly. Therefore, the steering torque Ts when the relative angular velocity ωee is in the dead zone is large. In this case, it is preferable to set so as to calculate the complementary relative rotation angle θee ′ based on the change amount of the steering torque Ts.

In the second embodiment, when the relative angular velocity ωee calculated based on the back electromotive force EMF is within the dead zone, the complementary relative rotation angle θee ′ calculated based on the steering torque Ts and the complementary relative Although the case where the angular velocity ωee ′ is applied has been described, the present invention is not limited to this, and the steering assist force generated by the electric motor 5 when the relative angular velocity ωee calculated based on the back electromotive force EMF is within the dead zone. Is determined based on, for example, the magnitude of the steering assist torque command value I _M ^* calculated by the command value calculation unit 42. When the steering assist force is small, the relative angular velocity ωee calculated based on the back electromotive force EMF, the relative rotation The steering assist control process is continued based on the angle θee and the relative angular acceleration α. When the steering assist force is large, the complementary relative rotation angle θee ′ based on the steering torque and the complementary relative It may continue the steering assist control processing based on the speed Omegaee 'and relative angular acceleration alpha.

  Further, in the second embodiment, the case has been described in which it is determined whether or not it is in the zero speed region based on whether or not the relative angular velocity ωee is within the dead zone. However, the present invention is not limited to this. The complementary relative angular velocity ωee ′ is selected even in a section where the angle information θee obtained from the electromotive voltage EMF is inaccurate (for example, when the zero cross point of the counter electromotive force EMF cannot be determined even if the relative angular velocity ωee is outside the dead zone). It may be.

Furthermore, in the second embodiment, the case where Δθ _M is set to “0” as the correction value has been described. However, the present invention is not limited to this, and the increase amount of the relative rotation angle θ _MP (n). May be set to such a value that can be suppressed to an extremely small value.
Furthermore, in the second embodiment, the case where the relative rotation angle change amount Δθ _M is calculated using the steering torque average value Ts _M obtained by averaging the steering torque Ts has been described, but the present invention is not limited to this. Instead, the relative rotation change amount Δθ _M may be calculated using the steering torque Ts itself as an input value. In short, any calculation value can be applied as long as the value is based on the steering torque Ts.

Next, a third embodiment of the present invention will be described with reference to FIG.
In the third embodiment, in the first and second embodiments described above, when calculating the relative angle information of the brushless motor according to the steering amount of the driver, the relative angle is calculated based on the back electromotive voltage of the brushless motor. Since the relative angular velocity constituting the angle information is calculated, when the back electromotive force voltage of the brushless motor cannot be normally detected, the relative angle information cannot be obtained, and the steering assist control is performed. I have to cancel. Therefore, in the third embodiment, the steering assist control can be continued even when the back electromotive voltage of the brushless motor cannot be normally detected.

That is, in the third embodiment, the microcomputer 30 executes the relative angle calculation process shown in FIG.
This relative angle calculation process is executed as a timer interrupt process at predetermined time intervals (for example, 10 msec). First, in step S81, the motor rotation angle θer detected by the resolver 18 and the motor rotation angle calculation unit 47 is normal. It is determined whether or not. This determination is performed by reading the fail-safe signal SF output in the motor rotation angle abnormality detection process of FIG. 9 and determining whether or not this is a logical value “0”.

If the determination result in step S81 is that the motor rotation angle θer is normal, the process proceeds to step S82, and the motor rotation angle θer is used to calculate the motor angular velocity ωe and the angular acceleration α before timer interruption processing. To return to a predetermined main program, and when the motor rotation angle θer is not normal, the process proceeds to step S83.
In this step S83, it is determined whether or not the relative angle information according to the driver's steering amount can be normally calculated. The determination of whether or not the calculation of the relative angle information is normal is performed, for example, by determining whether or not the motor terminal voltage detected by the motor terminal voltage detection unit 8 is normal. If normal, the process proceeds to step S84, the same relative angle information detection process as in the first embodiment described above is executed, and then the timer interrupt process is terminated to return to the predetermined main program, When the calculation of the relative angle information is abnormal, the process proceeds to step S85 and is the same as the complementary relative angle information calculation process of FIG. 15 executed by the complementary relative angle information calculation unit 70 in the second embodiment described above. After executing the relative angle information detection process for performing the process, the timer interrupt process is terminated and the process returns to the predetermined main program.

  According to the third embodiment, when the motor rotation angle detection unit composed of the resolver 18 and the motor rotation angle calculation unit 47 is normal, the process proceeds to step S82 and is detected by the motor rotation angle detection unit. The motor rotation angle θer is used to calculate the motor angular velocity ωe and the angular acceleration α. If the motor rotation angle detector becomes abnormal, it is determined whether the detection of the motor terminal voltage is normal. If the detection of the motor terminal voltage is normal, the process proceeds to step S84, where the relative angle information detection process according to the first embodiment described above is performed, the relative angular velocity ωee, the relative rotation angle θee, and the relative angular acceleration. α is calculated.

However, when the detection of the motor terminal voltage is abnormal, the relative angle information according to the first embodiment described above cannot be accurately calculated, so the process proceeds to step S85 and the second implementation described above. By performing the complementary angle information calculation process of FIG. 15 executed by the complementary angle information calculation unit 70 in the embodiment as the relative angle information detection process, the relative rotation based on the steering torque Ts without using the back electromotive force EMF is performed. The angle θ _MP is calculated, and the relative angular velocity ωee and the relative angular acceleration α are calculated using the calculated relative rotation angle θ _MP .

  As described above, according to the third embodiment, the calculation of the relative angle information can be performed in two stages. Therefore, the relative angular velocity ωee, the relative rotation angle based on the back electromotive force EMF according to the first embodiment described above. Even if relative angle information consisting of θee and relative angular acceleration α cannot be calculated, relative angle information consisting of relative rotational angle θee, relative angular velocity ωee, and relative angular acceleration α is calculated based on the steering torque Ts. Therefore, the range in which the steering assist control can be continued when an abnormality occurs can be widened, and more reliable steering assist control can be performed.

In the third embodiment, the case where the relative angle information detection process similar to that of the first embodiment described above is executed when the detection of the motor terminal voltage is normal has been described. The present invention is not limited, and the relative angle information detection process similar to that of the second embodiment described above may be executed.
In the third embodiment, the case where the relative angle calculation process based on the steering torque is performed when the relative angle calculation process based on the back electromotive voltage cannot be performed has been described. However, the present invention is not limited to this. When the relative angle calculation processing based on the back electromotive force cannot be performed, the relative angle is calculated based on the amount of change in the steering angle obtained from the steering angle sensor using the steering angle sensor used for other processing. Further, when the relative angle calculation process based on the steering angle cannot be performed, the relative angle calculation process based on the steering torque may be performed. The combination of these three steering angle calculation processes is based on a failure rate or the like. It may be determined.

In the first to third embodiments, the abnormality of the motor rotation angle detection system including the resolver 18 and the motor rotation angle detection circuit 32 is detected with reference to the abnormality determination map based on sin θ and cos θ. However, the present invention is not limited to this, and when the sin θ system and the cos θ system are short-circuited, a short circuit may be detected using the fact that sin ² θ + cos ² θ = 1. In this case, since sin θ and cos θ have the same value, the amplitude changes within a certain range, and the maximum is when the electrical angle is 45 degrees and the minimum when the electrical angle is 225 degrees. The relative rotation angle θee may be corrected to 45 degrees and 225 degrees by monitoring.

  In the first to third embodiments, the case where sin θ and cos θ are calculated by the motor rotation angle calculation process executed by the microcomputer 30 has been described. However, the present invention is not limited to this, and the motor rotation angle is not limited thereto. The sin θ and cos θ may be calculated in the detection circuit 32. Furthermore, instead of the resolver 18 as a motor rotation angle detection means, for example, as described in JP-A-2004-20548, the electric motor 5 Is magnetized so that the S pole and the N pole are equally divided into two by a virtual plane passing through the center of the permanent magnet constituting the encoder, and opposed to the S pole and the N pole of this encoder. Applying a rotation state detection device that provides magnetic sensors at positions that are 90 degrees out of phase and outputs sin θ and cos θ from these magnetic sensors. Good. Thus, when sin θ and cos θ are output as voltages from the motor rotation detecting means, for example, by determining whether the amplitudes of sin θ and cos θ are within a preset range by the microcomputer 30, sin θ When the amplitude of either one of cos θ and the cos θ is out of the set range, it may be determined that a ground fault abnormality or a power fault abnormality has occurred in the sin θ or cos θ system. In this case, assuming that the system of cos θ is normal, in the coordinate system of sin θ and cos θ, the angle at which cos θ is the maximum value is 0 degrees, and the angle at which the minimum value is 180 degrees is the center. Is 90 degrees or 270 degrees, and when cos θ reaches the maximum value, the relative rotation angle θee or the relative angular velocity ωee may be corrected to “0”. For detection of the maximum value in this case, a peak detection process or a peak detection circuit may be applied. If the peak value is known in advance, it is determined whether or not the peak value has been reached. When the maximum value can be detected and this peak value is affected by temperature or the like, for example, the peak values at 0 degrees and 180 degrees may be set as the peak values immediately before becoming abnormal. .

As described above, when one of sin θ and cos θ becomes abnormal, the peak value of the normal signal is monitored, and the angle at the time when the peak value is reached is adopted as a correction value for the relative rotation angle θee. You can also
Further, as shown in FIG. 19, three pole position sensors 101a such as a hall sensor that detects pole positions of a phase, b phase, and c phase provided in a normal three-phase brushless motor are used as the rotational position detection means of the motor. , 101b and 101c, the phase detection signals Sa, Sb and Sc output from these pole position sensors 101a, 101b and 101c have a phase difference of 120 degrees as shown in FIG. One pole position sensor 101i (i = a, b, c) that becomes abnormal can be detected based on the phase detection signals Sa, Sb, and Sc.

That is, the energization state represented by the on / off states of the phase detection signals Sa, Sb, and Sc repeats the energization states 1 to 6 as shown in the lowermost stage of FIG.
In this state, for example, when the a-phase pole position sensor 101a is fixed at a high level, as shown in FIG. 21, the energization states represented by the on / off states are “4”, “5”, and “6”. The energization state “7” in which the new a-phase detection signal Sa is at the high level, the b-phase detection signal Sb is at the high level, and the c-phase detection signal Sc is at the high level is repeated in a predetermined order. Although the abnormality can be detected at 7 ″, the pattern does not change from that in the normal state in the range of 0 to 180 degrees where the a-phase detection signal Sa originally becomes a high level. Here, the energization state “4” is a unique energization state that appears only once in the range of 0 ° to 360 °. This energization state “4” is the edge portion where the energization state is “5” or “6”. The angle can be read correctly. Similarly, when the b-phase detection signal Sb and the c-phase detection signal Sc are fixed at a high level, the energized states “2” and “1” exist as regions where the angle can be uniquely detected, respectively. There are points that can be recognized correctly.

  Similarly, when the a-phase detection signal Sa is fixed at a low level, as shown in FIG. 22, the angle is normally detected in a region (180 to 360 degrees) where the a-phase detection signal Sa is originally at a low level. The portion of the energized state “3” is unique in the range of 0 to 360 degrees, and the angle can be correctly read at the edge portions where the energized states are “2” and “1”. Further, when the b-phase detection signal Sb and the c-phase detection signal Sc are fixed at a high level, the energized states “5” and “6” exist as regions where the angle can be uniquely detected, and the angle is set correctly in the same manner. There is a point that can be recognized.

  As described above, the abnormality of the pole position sensors 101a to 101c for detecting the rotation of the rotating body including the motor pole position can be recognized by detecting the energized state “7” or “0”, and the energized state “7”. If an abnormal state is detected in step 1, if the energized states “1”, “2” and “4” are recognized, the normal angle can be corrected at the switching edge. If detected, if the energized states “3”, “5”, and “6” are recognized, the normal angle can be corrected at the switching edge.

  Therefore, when the rotational state detection device that outputs sin θ and cos θ described above is applied, or when the pole position sensors 101a to 101c are used, the fact that the actual angle can be accurately recognized exists. 23 can be executed. In this relative angle correction process, in step S91, the back electromotive force EMF is read, and then the process proceeds to step S92 to determine whether or not correction is necessary. This determination of whether or not the correction is required is made by determining whether or not the value of the back electromotive force EMF or the amount of change ΔEMF thereof is large. However, if the value of the back electromotive force EMF or its variable ΔEMF is large, it is determined that the correction is required, and the process proceeds to step S93 to detect the rotation state. It is determined whether or not the actual angle can be recognized from the detection signals from the apparatus or the pole position sensors 101a to 101c. When the actual angle cannot be recognized, the process waits until the actual angle can be recognized. The process proceeds to step S94, where the actual angle information is set as the relative angle θee, and the timer interrupt process is terminated. In this relative angle correction process, the process in step S92 corresponds to the correction required state detection means, and the processes in steps S93 and S94 correspond to the relative angle information correction means.

In the first to third embodiments, the case where the steering assist control is performed using the microcomputer 30 has been described. However, the present invention is not limited to this, and other arithmetic processing devices may be applied. In addition, it can be configured by hardware using an arithmetic circuit, an adder circuit, a comparison circuit, and the like.
Further, in the first to third embodiments, the case where the steering assist control process is executed by the microcomputer 30 and the pulse width control process is executed by the FET gate drive circuit 22 has been described, but the present invention is not limited to this. Instead, the microcomputer 30 may execute both the steering assist control process and the pulse width control process, and the microcomputer 30 may directly drive and control the inverter circuit 21.

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. It is a block which shows the specific structure of the electric current command value calculation part of FIG. 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 motor rotation angle abnormality detection process procedure performed with the microcomputer of a control apparatus. It is explanatory drawing which shows the abnormality determination map used in FIG. It is a flowchart which shows an example of the steering assistance control processing procedure performed with the microcomputer of a control apparatus. It is a flowchart which shows an example of a procedure of the relative angle information calculation process performed with the microcomputer of a control apparatus. It is a characteristic diagram which shows the relationship between the magnetic field vector relative angle error of the rotor and stator of an electric motor, and the absolute value of the energy which generate | occur | produces in a rotor. It is a functional block diagram which shows the 2nd Embodiment of this invention. It is a flowchart which shows an example of the relative angle calculation process procedure of 2nd Embodiment. It is a functional block diagram of a motor rotation angle estimation process. It is a block diagram which shows an angular velocity and an angular acceleration calculating part. It is a flowchart which shows an example of the relative angle detection processing procedure of the 3rd Embodiment of this invention. It is a block diagram which shows the specific example of the control apparatus in other embodiment of this invention. It is a signal waveform diagram which shows a three-phase detection signal. It is a signal waveform diagram when the a-phase detection signal is fixed at a high level. It is a signal waveform diagram when the a-phase detection signal is fixed at a low level. It is a flowchart which shows an example of the relative angle correction process sequence in other embodiment of this invention.

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 ... Reduction gear, 17 ... Torque sensor, 18 ... Resolver, 21 ... Inverter circuit, DESCRIPTION OF SYMBOLS 22 ... FET gate drive circuit, 30 ... Microcomputer, 32 ... Motor rotation angle detection circuit, 33 ... Vehicle speed sensor, 42 ... Current command value calculation part, 42A ... Steering assist torque command value calculation part, 42B ... Command value compensation part, 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 ... dither processing 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 ... dead zone 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, 101 a to 101 c .. pole position detection sensor

Claims (11)

An electric motor for generating a steering assist force for the steering system, a steering torque detecting means for detecting a steering torque transmitted to the steering system, and a steering assist command value based on the steering torque detected by the steering torque detecting means And an electric power steering device comprising motor control means for driving and controlling the electric motor based on the calculated steering assist command value,
A motor relative angle information calculation unit that calculates relative angle information of the electric motor in accordance with a steering amount of the driver with respect to the steering system, and the motor relative angle information calculation unit cannot obtain relative angle information. And a motor relative angle detection unit having a relative angle information complementing unit that prevents generation of relative angle information at all times, and the motor control unit is based on the relative angle information detected by the motor relative angle detection unit. An electric power steering apparatus configured to drive and control the electric motor from an arbitrary actual angle without setting an initial angle at the start of driving. An electric motor that generates a steering assist force for the steering system, a motor rotation angle detection unit that detects a rotation angle of the electric motor, a steering torque detection unit that detects a steering torque transmitted to the steering system, and the steering A motor that calculates a steering assist command value based on the steering torque detected by the torque detection means, and drives and controls the electric motor based on the calculated steering assist command value and the motor rotation angle detected by the motor rotation angle detection means. An electric power steering device comprising a control means,
Motor rotation angle abnormality detection means for detecting an abnormality of the motor rotation angle detection means, a motor relative angle information calculation unit for calculating relative angle information of the electric motor according to a steering amount of a driver with respect to the steering system, A motor relative angle detecting means having a relative angle information complementing unit that prevents the motor relative angle information calculating unit from being in a state in which the relative angle information cannot be obtained and always generates relative angle information; The motor control means selects the motor rotation angle information detected by the rotation angle detection means when the motor rotation angle abnormality detection means has not detected an abnormality of the motor rotation angle abnormality detection means, and the motor rotation angle When the abnormality detecting means detects an abnormality of the motor rotation angle detecting means, the relative angle information detected by the motor relative angle detecting means is selected, and the selected motor rotation is selected. An electric power steering apparatus characterized by being configured to drive control the electric motor based on the angular information or the relative angle information.   The said motor control means is comprised so that it may drive from arbitrary real angles, without setting an initial angle, when driving-controlling the said electric motor based on the said relative angle information. The electric power steering device described in 1.   The motor relative angle information complementing unit is a state in which relative angle information cannot be obtained by adding an offset value for changing the sign every predetermined cycle when necessary to the relative angle information calculated by the motor relative angle information calculating unit. The electric power steering device according to any one of claims 1 to 3, wherein the electric power steering device is configured to prevent the occurrence of the electric power steering.   The motor relative angle information complementing unit detects a relative angular velocity, and when the detected relative angular velocity is at least near zero, the motor relative angle calculating unit reliably exceeds the dead zone until the relative angle information is obtained. The electric power steering apparatus according to claim 4, wherein the offset amount and the period are determined.   The motor relative angle calculation unit includes a relative angle calculation abnormality detection unit that detects a relative angle calculation abnormality state that detects an abnormality of at least one of the calculated relative angle information and an input value for calculating the relative angle information. When the relative angle calculation abnormality detecting unit detects the relative angle calculation abnormality state, the relative angle information is calculated based on another input value in which no abnormality is detected. The electric power steering device according to any one of claims 1 to 5.   The said motor relative angle calculation part is comprised so that the rotation direction of the said electric motor may be determined based on the steering torque detected by the said steering torque detection means, The any one of Claim 1 thru | or 6 characterized by the above-mentioned. The electric power steering device according to the item.   The motor relative angle calculation unit detects a necessary correction state detecting unit that detects a correction necessary state in which an error with respect to the actual angle of the calculated motor relative angle increases, and the correction state detection unit detects the necessary correction state. 8. The electric power steering apparatus according to claim 1, further comprising a relative angle information correction unit that corrects the relative angle information.   The motor rotation angle detection means is configured to output two or more different rotation angle detection signals of a sine wave and a cosine wave, or the motor rotation angle abnormality detection means is configured to output a sine wave and a cosine wave. The motor relative angle calculation unit detects a motor rotation angle abnormality when the amplitude of any one of the motors is out of a predetermined range, and the motor relative angle calculation unit is in a correction state in which an error with respect to the actual angle of the calculated motor relative angle increases. And a relative angle information correction unit that corrects the relative angle information when the required correction state is detected by the required correction state detection unit. When the amplitude of the other one of the sine wave and cosine wave reaches the maximum value and the minimum value, it is detected that the correction is necessary, and the relative angle correction means At a real angle, Serial electric power steering apparatus according to claim 2 or 3, characterized in that it is configured to correct the relative angle information.   The motor rotation angle detection means is configured to output two types of rotation angle detection signals of a sine wave and a cosine wave, and the motor rotation angle abnormality detection means includes a square value of the sine wave and a square value of the cosine wave. By detecting whether or not the sum of the two is “1”, a short circuit between the two waves is detected, and the motor relative angle calculation unit is in a correction state requiring an increase in the error of the calculated motor relative angle with respect to the actual angle. A correction-necessity detection unit for detecting this, and a relative angle information correction unit that corrects the relative angle information when the correction-necessity detection state is detected by the correction-necessity detection unit. When the amplitude of the sine wave and cosine wave reaches the minimum value and the maximum value, it is detected that the correction is necessary, and the relative angle information correction means is the actual angle at that time when the correction is required. And the relative angle The electric power steering apparatus according to claim 2 or 3, characterized in that it is configured to correct the information.   The motor rotation angle detection means includes a pole position sensor that outputs a multi-phase pole position signal, and the motor rotation angle abnormality detection means has one pole based on the pole position signal output from the pole position sensor. An abnormality of the position sensor is detected, and the motor relative angle calculation unit detects a correction state that is required to detect that the error with respect to the actual angle of the calculated motor relative angle is increased, and the correction state detection is required. Relative angle information correction means for correcting the relative angle information when the required correction state is detected by the means, and the required correction state detection means is a pole that is uniquely determined from among 360 degrees according to the abnormal state of the pole position sensor. When the position signal arrangement is reached, it is detected that the correction is required, and the relative angle information correction unit is configured to detect the relative angle at the actual angle of the corresponding polar position signal arrangement when the correction is required. The electric power steering apparatus according to claim 2 or 3, characterized in that it is configured to correct the information.

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