JPH08251975A - Motor power steering system - Google Patents

Abstract

PURPOSE: To obtain a motor power steering system in which the steering wheel can be operated even when the sensor signal from a position sensor is abnormal by a constitution wherein an excitation control means suppresses driving of a five-phase brushless motor when a combination, corresponding to the state of a position detection signal is not present on a table. CONSTITUTION: Exciting coils 26a-26e to be excited are designated based on the position detection signals from a phase detection element 31 (31a-31e) with reference to a table representative of the correspondence between the preset combination of position detection states for normal position detection signals and the exciting coils 26a-26e of a five-phase brushless motor to be excited. For example, when an abnormal detection signal, is generated due to abnormal wiring of the phase detection element 31 (31a-31e) and a combination corresponding to the combination of the states of position detection signal is not present on the table, driving of the five-phase brushless motor is suppressed to reduce the auxiliary steering power for the steering system or stop driving of the five-phase brushless motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus in which a steering assist force is applied to a steering system of a vehicle by an electric motor.

[0002]

2. Description of the Related Art Conventionally, as an electric power steering apparatus, a steering torque detector such as a torque sensor for detecting steering torque is attached to an input shaft to which a steering wheel is fixed, and steering torque detected by the steering torque detector is used. It is known that a corresponding auxiliary torque is generated by an electric motor to assist the steering torque.

This electric motor is controlled by a controller. The controller controls an assist current based on a steering torque detection signal detected by a torque sensor and a vehicle speed detected by a vehicle speed sensor, and the assist current is electrically driven. By supplying the electric power to the motor, the steering force of the steering wheel is assisted, and this electric motor assists the steering operation, for example, during low-speed cornering or when entering the garage. It is designed to give a feeling of response and ensure running stability.

Conventionally, as an electric motor, it is known that a DC motor with a brush is used as an assist drive source, and when abnormality of the DC motor with a brush or a controller is detected, power transmission is performed by an electromagnetic wave. The clutch disengages to prevent the steering wheel from being disabled.

[0005]

However, in the above-mentioned conventional electric power steering apparatus, since the brush DC motor is used, the brush DC motor is reliable because the brush is damaged or worn. It has the drawback of being slightly lacking in sex. Therefore, in recent years, it has been considered to use a highly reliable brushless motor used for various rotation controls as an assist drive source. The use of this brushless motor is also advantageous in terms of durability and reduction of inertia.

In the brushless motor, it is necessary to detect the position of the rotor instead of having no brush, and the position of the rotor is detected by a position sensor such as a Hall element or a magnetic resistance element. Since there is no brush in this brushless motor, an abnormality rarely occurs in the brushless motor itself, but an abnormality may occur in the position sensor such as a hall element or the wiring of the position sensor.

If the sensor signal of the position sensor becomes abnormal due to these abnormalities, the correct position of the rotor cannot be detected. Therefore, since the controller cannot perform normal control, the output torque of the brushless motor fluctuates, and in the worst case, a steering assist force that works in a direction different from the steering direction is generated.
The steering wheel may be locked so that it cannot be rotated in the desired steering direction, and the steering wheel may not be operated. Therefore, it is necessary to detect abnormality in the sensor signal of the position sensor.

A commonly used brushless motor is a three-phase brushless motor, and in the case of this three-phase brushless motor, the position sensor requires three as many as the number of excitation phases. Then, the three position sensors output sensor signals of "H" for the N pole and "L" for the S pole, depending on the polarities of the permanent magnets for position detection arranged on the rotor. However, the rotational position of the rotor is detected according to the detection states of the sensor signals of the three position sensors.

In the case of a three-phase brushless motor, since three position sensors are required, there are eight combinations of detection states of the sensor signals of each position sensor, as shown in FIG. The rotational position of the rotor is detected by the combination of (1) to (6), and the exciting coil to be excited and the energizing direction of the exciting coil are set from this combination.

Then, as shown by "7" and "8" in FIG. 15, when the sensor signals are all "H" or "L", it is determined that the sensor signal of the position sensor is abnormal, and the abnormality notification is issued. Is supposed to do. However, for example,
Short circuit, contact failure, etc. of the wiring connector portion for the sensor signal are overlapped, and the sensor signals of the two position sensors are fixed to “H” or “L”. For example, as shown in FIG. 16, the sensor signals Sa and Sb are When fixed to "H" and "L" respectively, the sensor signal Sc outputs either "H" or "L", so that the sensor signals Sa and S are output.
When the combination of b and Sc is represented as (Sa, Sb, Sc), (Sa, Sb, Sc) becomes (H, L, L) or (H, L, H), which is shown in FIG. (2) or (3)
In this state, the controller cannot detect that there is an abnormality in the sensor signal.Therefore, if you continue to drive the motor, the torque in the direction opposite to the direction you want the motor to rotate Therefore, there is an unsolved problem that it is unsuitable for application to the electric power steering device because of the occurrence.

Therefore, the present invention has been made by paying attention to the unsolved problem of the above conventional example, and when a brushless motor is used as an assist drive source, the sensor signal of the position sensor becomes abnormal due to some abnormality. It is an object of the present invention to provide a highly reliable electric power steering device capable of ensuring safety without the operation of the steering wheel being disabled even in the case of an emergency.

[0012]

In order to achieve the above object, an electric power steering apparatus according to a first aspect of the present invention is provided.
A five-phase brushless motor that generates a steering assist force for the steering system, five phase detection elements that detect the rotational position of the rotor of the five-phase brushless motor, and a normal position detection signal of the phase detection element The combination of position detection status and the above 5
Excitation control means for designating an excitation coil corresponding to the position detection state of the position detection signal by referring to the table having a table showing the correspondence with the excitation coil of the phase-phase brushless motor, and the 5-phase brushless motor A motor control means for outputting a control signal for generating a steering assist force to the steering system, and an energizing direction and an energizing amount to an exciting coil designated by the exciting control means based on the control signal from the motor controlling means. And a drive circuit that controls the drive circuit, and the excitation control unit includes a motor suppressing unit that suppresses the drive of the five-phase brushless motor when there is no combination corresponding to the position detection state of the position detection signal in the table. Is characterized by.

The electric power steering apparatus according to the second aspect of the invention produces a steering assist force for the steering system.
Phase brushless motor, five phase detection elements for detecting the rotational position of the rotor of the five-phase brushless motor, a combination of the position detection state of the position detection signal of the phase detection element at the normal time, and the five-phase brushless motor Excitation control means for holding an excitation coil to be excited and designating an excitation coil corresponding to the position detection state of the position detection signal by referring to the table, and the steering system from the 5-phase brushless motor A motor control means for outputting a control signal for generating a steering assist force, and a drive for controlling the energizing direction and the energizing amount to the exciting coil designated by the exciting control means based on the control signal from the motor controlling means. A circuit, the excitation control means is configured to control all the excitation coils when there is no combination corresponding to the position detection state of the position detection signal in the table. And abnormality processing means for canceling the designation of Le, the combination of the position detection state of the position detection signal,
It is characterized by comprising a motor stop means for stopping the drive of the 5-phase brushless motor when the combination is such that the 5-phase brushless motor generates a steering assist force in a direction opposite to the steering direction of the steering wheel.

[0014]

The electric power steering apparatus according to the first aspect of the present invention is based on the position detection signal from the phase detection element, and is based on the position detection signal set by the phase detection element. The excitation coil to be excited by the excitation control means is designated by referring to the table showing the correspondence with the excitation coil, and the energization direction and the energization amount to the designated excitation coil are driven based on the control signal from the motor control means. A predetermined steering assist force is generated from the five-phase brushless motor by controlling by, and an abnormality occurs in the position detection signal due to, for example, a wiring abnormality of the phase detection element, and a combination corresponding to the combination of the position detection states of the position detection signal is generated. When it is not on the table, the motor restraining means restrains the drive of the five-phase brushless motor to assist the steering system. Or smaller, or to stop the drive of the five-phase brushless motor.

The electric power steering apparatus according to a second aspect of the invention is based on the position detection signal from the phase detection element, and is a five-phase brushless to be excited and a combination of a preset position detection state of the position detection signal in a normal state. The excitation control unit specifies the excitation coil to be excited by referring to the table showing the correspondence with the excitation coil of the motor, and based on the control signal from the motor control unit, the energization direction and the energization amount to the specified excitation coil are specified. A predetermined steering assist force is generated from the five-phase brushless motor by controlling the drive circuit, and an abnormality occurs in the position detection signal due to, for example, a wiring abnormality of the phase detection element, which corresponds to a combination of the position detection states of the position detection signal. When the combination is not in the table, the abnormality processing means cancels the designation of all the excitation coils and switches to the 5-phase brushless motor. When the current supply is stopped to stop the generation of steering assist force, and then the combination corresponding to the combination of the position detection states of the position detection signal again occurs, the predetermined exciting coil obtained from the table is designated and the 5-phase The motor is stopped when a predetermined steering assist force is generated from the brushless motor, and the combination of the position detection states of the position detection signals is a combination in which the 5-phase brushless motor generates a steering assist force in the direction opposite to the steering direction of the steering wheel. The driving of the 5-phase brushless motor is stopped by the means, and no steering assist force is generated thereafter.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing the configuration of the first embodiment of the present invention. In the figure, 1 is a steering wheel,
The steering force applied to the steering wheel 1 is transmitted to the steering shaft 2 including the input shaft 2a and the output shaft 2b. One end of the input shaft 2a is connected to the steering wheel 1, and the other end is connected to one end of the output shaft 2b via the torque sensor 3. Then, the steering force transmitted to the output shaft 2b is transmitted to the lower shaft 5 via the universal joint 4 and further transmitted to the pinion shaft 7 via the universal joint 6. The steering force is further transmitted to the tie rod 9 via the steering gear 8 to steer the steered wheels. The steering gear 8 is of a rack-and-pinion type having a pinion 8a and a rack 8b, and the rotary motion transmitted to the pinion 8a is converted into a linear motion by the rack 8b.

A reduction gear 10 for transmitting an auxiliary steering force (assist force) to the output shaft 2b is connected to the output shaft 2b of the steering shaft 2, and the reduction gear 10 and the five-phase generating auxiliary steering force. The output shaft of the motor 12, which is a brushless motor, is connected. The torque sensor 3 is disposed on the steering wheel 1 and detects the steering torque transmitted to the input shaft 2a. For example, the torsion bar is twisted between the input shaft 2a and the output shaft 2b. It is configured to be converted into an angular displacement, and the torsional angular displacement is detected by a potentiometer. The occupant steers the steering wheel 1 to form an analog voltage according to the magnitude and direction of the torsion generated in the steering shaft 2. The detected torque value T _V is output. Then, for example, when the steering wheel 1 is in the neutral state, the torque sensor 3 outputs a predetermined neutral voltage V ₀ as the torque detection signal T _V , and when the steering wheel 1 is turned right from this, the torque sensor 3 When the voltage that increases from the neutral voltage V ₀ according to the steering torque is turned to the left, a voltage that decreases from the neutral voltage V ₀ according to the steering torque at that time is output.

Reference numeral 13 is a controller for controlling the drive of the motor 12 and for controlling the steering assist force to the steering system, which is operated by being supplied with power from the battery 16 mounted on the vehicle. The negative electrode of the battery 16 is grounded, and the positive electrode of the battery 16 is connected to the controller 13 via the ignition switch 14 and the fuse 15a for starting the engine and directly connected to the controller 13 via the fuse 15b. The power supplied via 15b is used, for example, for memory backup. Then, the controller 13 drives and controls the motor 12 based on the detected torque value T _V from the torque sensor 3 and, for example, the detected vehicle speed value V _P from the vehicle speed sensor 17 arranged on the output shaft of the transmission (not shown). .

FIG. 2 is a sectional view showing the structure of the motor 12. The motor 12 includes a cylindrical housing 22 and
The bearing 23 is arranged along the axis of the housing 22.
A permanent magnet 25 for driving a motor, which is fixed to a rotatable shaft 24 by a and 23b, and a five-phase exciting coil 26a, which is fixed to an inner peripheral surface of the housing 22 so as to surround the permanent magnet 25, 26b, 26c, 26d
And 26e are wound around the stator 26, and the rotatable shaft 24 and the permanent magnet 25 form a rotatable rotor 27.

A ring-shaped permanent magnet 28 for phase detection is fixed to the rotor 27 in the vicinity of the end of the rotary shaft 24 on the side where the bearing 23b is arranged (lower side in FIG. 2). The magnet 28 has the same number of poles as the number of poles magnetized by the permanent magnet 25, which are alternately magnetized in the circumferential direction at equal intervals.
A total of 6 poles are magnetized, each having 3 poles and 3 poles.

On the other hand, the bearing 2 of the housing 22
On the inner end surface on the side where 3b is arranged (lower side in FIG. 2), a support substrate 30 made of a ring-shaped thin plate is arranged via a stay 29 so that its inner insulating portion faces the permanent magnet 28. On the surface of the supporting substrate 30 facing the permanent magnet 28 side, a phase detecting element 31 such as a Hall element is fixed so as to face the permanent magnet 28.

Actually, five phase detecting elements 31 are provided at equal intervals in the circumferential direction in correspondence with the driving timing of the exciting coils 26a to 26e, but FIG. Only one of these is shown. When the magnetic pole of the permanent magnet 28 facing the phase detection elements 31a to 31e is the N pole, the sensor signal as the position detection signal of "H" is output, and when it is the S pole, the sensor signal of "L" is output. Output the sensor signal.

The rotational position of the rotor 27 is recognized by utilizing the fact that the output of each phase detection element 31 changes due to the magnetic pole of the permanent magnet 28 facing it, and the motor drive circuit 64, which will be described later, responds accordingly. With respect to the five-phase exciting coils 26a to 26e forming the coil circuit 35, the coils to be excited are sequentially switched one by one by a four-phase excitation method in which four phases are simultaneously excited, and the rotor 27 is appropriately rotated. ing.

On the other hand, the permanent magnet 25 constituting the rotor 27
For example, the S pole and the N pole are each 3 poles, and a total of 6 poles are magnetized at equal intervals in the circumferential direction. Here, in this case, the S-pole and the N-pole are applied to the permanent magnets 25 having three poles in total, six poles in total, but the S-pole and the N-pole are alternately arranged at equal intervals in the circumferential direction. If it is magnetized, it may have two poles of S pole and N pole, or may have a plurality of poles.

The coil circuit 35 is formed of five-phase exciting coils 26a to 26e, star-connected in a Y shape as shown in FIG. 3, and surrounds the outer peripheral surface of the rotor 27 at an electrical angle of 72 degrees. It is arranged as follows. Here, in the four-phase excitation method, the motor current flows in four phases, but the current is inversely proportional to the coil resistance. Therefore, in order to flow the current in good balance in each phase, the excitation coils 26a to 26e
The coil resistances of are all formed to be equal.

The stator 26 is the stator core 2
Thirty slots are formed on the inner peripheral surface of the 6'at equal intervals, and the same number of protrusions are formed between the slots.
Each of the exciting coils 26a-2
6e is wound around. Therefore, the winding development view of one set of the above-mentioned protrusions is as shown in FIG. 4, and the electrical angle between the protrusions 41 to 50 is 360 degrees.

The exciting coil 26a is wound around the convex portions 41 and 45 around the convex portions 42 to 44, and the exciting coil 26b is wound around the convex portions 43 and 47 around the convex portions 44 to 46. The exciting coil 26c has a convex portion 45.
, 49, and the like, each of which is wound around five convex portions, one end of which is collectively connected, and the other end is connected to the motor drive circuit 64.

FIG. 3 is a block diagram showing the configuration of the controller 13. The controller 13 is composed of, for example, a control circuit 60, an FET gate drive circuit 62, a motor drive circuit 64, a current detection circuit 66, a rotor position detection circuit 68, and a relay drive circuit 70. here,
The control circuit 60 corresponds to the motor control means, the FET gate drive circuit 62 and the motor drive circuit 64 correspond to the drive circuits, and the rotor position detection circuit 68 corresponds to the excitation control means and the motor suppression means.

The above-mentioned control circuit 60 is composed of, for example, a microcomputer, and has at least an interface section for performing input / output processing with externally connected equipment, ROM, RA.
And a storage unit such as M. And the torque sensor 3
The detected torque direction T is determined by determining whether the torque detection value T _V , which is an analog voltage from the above, is higher than a predetermined neutral voltage V _0, and a predetermined process is performed to determine the torque detection value T. the vehicle speed detection value V _P of a pulse signal corresponding to the rotation of the output shaft from the sensor 17 by integrating the number of pulses based on per unit time to calculate the vehicle speed detection value V. Then, based on these input signals, for example, a motor drive signal S _M to be supplied to the motor 12 is calculated by PID control (proportional / integral / derivative), and PWM (Pulse Width Modulation) is performed based on this motor drive signal S _M. Signal, and based on this PWM signal, pulse width modulation signal PWM
Are formed and output to the FET gate drive circuit 62.

Further, the control circuit 60 executes a predetermined failure detection process at the time of start-up, and when it is normal, the relay control signal S _R to the relay drive circuit 70 is set to "HIG".
Output as "H", and the rotor position detection circuit 68 outputs "1".
If an abnormality occurs when the abnormal signal of is input,
Relay control signal S for opening the fail relay 70a
_R is formed and output to the relay drive circuit 70, and predetermined processing is performed when an abnormality occurs, such as turning on an abnormality lamp.

The relay drive circuit 70 operates based on the relay control signal S _R from the control circuit 60. When the relay control signal S _R is "HIGH", the coil 70L is energized to close the fail relay 70a. When the relay control signal S _R is "LOW", the energization of the coil 70L is stopped and the fail relay 70a is opened. As a result, the power supply to the motor drive circuit 64 is turned on / off.

The FET gate drive circuit 62 is composed of, for example, a multiplexer, and the pulse width modulation signal PWM and the direction signal from the control circuit 60 and the upper side gate signals Ga1 to Ge1 and the lower side from the rotor position detection circuit 68. When the gate signals Ga2 to Ge2 are input and the direction signal is forward rotation, the pulse width modulation signal PWM is "HIGH" at the gate terminal of the corresponding transistor of the motor drive circuit 64 specified by the gate signals Ga1 to Ge2. When a predetermined voltage is supplied for a certain period of time and the direction signal is reversely rotated, the upper gate signals Ga1 to Ge1 are processed as lower gate signals and the lower gate signals Ga2 to Ge2 are processed as upper gate signals. While the pulse width modulation signal PWM is "HIGH" at the gate terminal of the transistor
A predetermined voltage is supplied.

The current detection circuit 66 has, for example, a current detection resistor, amplifies and removes the voltage generated across the resistor and outputs it as a motor current detection signal I to the control circuit 60. In the current detection circuit 66, the motor current detection signal I
Sufficient filtering is applied to each signal so that the effective value of is obtained. The motor drive circuit 64 includes transistors Ta1, Tb1, Tc1, Td1, Te1, Ta which are composed of ten field effect transistors.
2, Tb2, Tc2, Td2, Te2. These transistors Ta1 and Te2 are Ta1 and T2.
a2, Tb1 and Tb2, corresponding transistors are connected in series, and each of the series circuits connected in series is arranged in parallel between both terminals of the power supply and the transistors in series are connected. The portion is electrically connected to the outer ends of the exciting coils 26a to 26e (the side opposite to the center side of the star connection).

The gate voltage of each of the transistors Ta1 to Te2 is controlled by the FET gate drive circuit 62 based on the output of the phase detecting element 31 described above. In the motor drive circuit 64, the directions and magnitudes of the exciting currents to the exciting coils 26a to 26e are
Specifically, as shown in FIG. 5, each transistor T
The ON / OFF timings of a1 to Te2 are as shown by the gate signals (upper row) and (lower row) in FIG. Here, in FIG. 5, the phase a corresponds to the exciting coil 26a, and the phase b
The phase corresponds to the exciting coil 26b, each phase corresponds to each exciting coil, and the e phase corresponds to the exciting coil 26e.

In FIG. 5, assuming that the rotor 27 is in the state of d ₁ , for example, this corresponds to the section (1). Therefore, as shown in FIG.
a1, Tb1 and the lower transistors Tc2, Td2
Is on, and the other transistors are off, so that current flows from the outer ends of the exciting coils 26a and 26b, and current flows from the wire connecting side of the exciting coils 26c and 26d. As a result, in the winding development view of FIG. 4, a current flowing upward in FIG. 4 flows on both sides of the convex portions 41, 42, 50, and a current flowing downward in FIG. 4 flows on both sides of the convex portions 45 to 47. From the convex portions 43 and 4
An N pole is generated at 4 and an S pole is generated at the convex portions 48 and 49. Therefore, the rotor 27 is rotated by the magnetic attractive force and the repulsive force between the N or S pole of the rotor 27 and the N or S pole generated in the convex portion.

Then, when the rotor 27 rotates and shifts to the state of d ₂ in FIG. 5, this corresponds to the section (2), so that as shown in FIG.
Since Tb1 and the transistors Td2 and Te2 on the lower side are in the on state, and the other transistors are in the off state,
Therefore, a current flows through the exciting coils 26a and 26b from the outer end side, and a current flows through the exciting coils 26d and 26e from the connection side. As a result, in the winding development view of FIG. 4, a current flowing upward in FIG. 4 flows on both sides of the convex portions 41 to 43, and a current flowing downward in FIG. 4 flows on both sides of the convex portions 46 to 48. N on the convex portions 44 and 45
A pole is generated, and an S pole is generated on the convex portions 49 and 50. Then, similarly to the above, the rotor 27 is further rotated by the magnetic attraction force and the repulsive force between the N or S pole of the rotor 27 and the N or S pole generated in the convex portion. Repeat this operation to activate each transistor at the timing shown in FIG.
As shown in FIG. 5, the exciting coil that sequentially excites one phase at an electrical angle of 36 degrees is switched, and one phase is switched at an electrical angle of 14 degrees.
By exciting for 4 degrees, the N pole or the S pole generated in each convex portion of the stator 26 sequentially moves, whereby the rotor 27 is continuously rotated.

Returning to FIG. 3, the rotor position detection circuit 68
Is formed of, for example, a microcomputer, and includes at least an interface unit that performs input / output processing with an externally connected device and a storage unit such as a ROM or a RAM. Then, the phase detection elements 31a to 31a shown in FIG.
The storage unit includes a gate setting table T1 indicating the correspondence between the combinations of the detection states of the sensor signals Sa to Se that are the outputs of 31e, the set values of the abnormal signal, and the upper side gate signal and the lower side gate signal.

Then, the rotor position detection circuit 68 inputs the sensor signals Sa to Se from the respective phase detection elements 31a to 31e, obtains a combination of detection states of the corresponding sensor signals based on the gate setting table T1, The corresponding gate signals Ga1 to Ge2 are obtained and output to the FET gate drive circuit 62, and the designated abnormality signal is output to the control circuit 60.

Here, the gate setting table T1 is set so that the rotational position of the rotor 27 can be detected from the combination of the detection states of the respective sensor signals. There is a combination of the detection states of the sensor signals corresponding to each of the sections (1) to (10) for each 36 degrees in the electrical angle of FIG. 5 and the upper stage for specifying the coil to be excited set in each section. The correspondence with the gate signals on the lower side and the lower side is set. Then, in the case of the combination corresponding to each section (1) to (10), the abnormal signal is set to “0”, that is, as normal, and when the combination does not correspond to each section (1) to (10) The abnormal signal is set to "1", that is, abnormal. Further, when the combination does not correspond to each section (1) to (10), all the gate signals Ga1 to Ge2 are set to "0". The current is not supplied to the coil circuit 35. Then, the sensor signals Sa to S
"H" of e indicates that it is excited to the N pole and "L" to that of the S pole. "1" of the gate signals Ga1 to Ge2 sets the corresponding transistor to the ON state, and "0" to the OFF state. Indicates that it is set to.

Next, the processing procedure of the motor drive control processing for forming the pulse width modulation signal PWM of the control circuit 60 is shown in FIG.
It will be described based on the flowchart shown in FIG. The motor drive control process is performed by a timer interrupt at preset predetermined time intervals. The control circuit 60 executes a predetermined failure detection process when the ignition switch 14 is turned on, and outputs a relay control signal S _R as “HIGH” when no abnormality is detected,
Further, it is assumed that the command signal is output as "LOW" to the FET gate drive circuit 62 as an initial value. As a result, the relay drive circuit 70 energizes the coil 70L to close the fail relay 70a,
The motor drive circuit 64 is energized.

When the ignition switch 14 is turned on and the predetermined failure detection process is completed, the control circuit 60 executes the motor drive control process of FIG. 7, and first, in step S1, the torque detection from the torque sensor 3 is performed. The value T _V is read and a predetermined process is performed to obtain a torque detection value T that represents the direction of torque generation with positive and negative signs. When the detected torque value T is positive, the steering wheel 1 is turned to the right, and when the detected torque value T is negative, the steering wheel 1 is turned to the left.

Next, in step S2, the vehicle speed detection value V calculated based on the vehicle speed detection value V _P, which is a pulse signal from the vehicle speed sensor 17, is read in advance. Then, the process proceeds to step S3, and for example, referring to a characteristic diagram showing the correspondence between the steering torque, the vehicle speed, and the motor current shown in FIG. 8, the motor current corresponding to the torque detection value T and the vehicle speed detection value V is calculated. It is searched and set as the motor current command value S _I.

Here, this characteristic diagram shows that the motor current required to drive the motor 12 to generate an auxiliary steering force corresponding to the steering torque input to the steering shaft 2 and the steering It shows the correspondence between torque and vehicle speed.The motor current command value increases as the vehicle speed decreases, the motor current command value increases as the steering torque increases, and it does not increase beyond a certain value. Is set.

Then, in step S4, the motor current detection value I from the current detection circuit 66 is read and converted into a digital signal to obtain the motor current detection value i. Next, in step S5, the detected motor current value i
As a feedback signal, and based on the motor current command value Si and the motor current detection value i set in step S4,
The motor drive signal S _M is calculated by PID control.

Then, the process proceeds to step S6, where the motor drive signal S _M is S _M ≧ 0, a direction signal for setting the rotation direction of the motor to positive rotation is formed, and when S _M <0. A pulse width modulation signal PWM for forming a direction signal for setting the rotation direction of the motor to reverse rotation and further supplying a drive current according to the motor drive signal S _M to the motor 12
Form the FE signal and the direction signal and the pulse width modulation signal PWM.
Output to the T gate drive circuit 62. Then, the process ends and the process returns to the main program.

Next, the operation of the first embodiment will be described.
Now, if the ignition switch 14 is turned on while the vehicle is stopped, the power supply from the battery 16 is supplied to the controller 13 and the controller 13 starts operating. Then, the control circuit 60 performs a predetermined failure monitoring process, and outputs the relay control signal S _R as “HIGH” to the relay drive circuit 70 if there is no abnormality, and also outputs the pulse width modulation signal PWM as “LOW” as an initial value. ”
Output as As a result, the fail relay 70a is closed, so that the motor 9th circuit 64 is energized. At this time, however, each transistor of the motor drive circuit 64 is in an off state, so the motor 12 does not rotate.

From the characteristic diagram of FIG. 8, the torque detection value T is substantially zero and the motor current command value S _I is in the non-steering state while the controller 13 is stopped and the vehicle is in the running state. Since it becomes substantially zero, the control circuit 60 outputs the pulse width modulation signal PWM as “LOW”, and thus the motor drive circuit 64 does not supply the current to the coil circuit 35.

Then, for example, when the driver steers to the right while driving, the control circuit 60 refers to the characteristic diagram shown in FIG. 8 based on the detected torque value T and the detected vehicle speed V. Then, the corresponding motor current command value is searched for. At this time, for example, when the vehicle is traveling at a low speed and the steering torque is large, a large auxiliary steering force is required. Therefore, the motor current command value S _I is large. When the vehicle is traveling at a high speed, the motor current command value S _I is set to a small value in order to generate a small auxiliary steering force so that the steering wheel 1 feels responsive. Similarly, when the steering torque is small, sets the higher the vehicle speed is less large motor current command value S _I, to a small motor current instruction value S _I to be a responsive feeling of the steering wheel 1 as the vehicle speed increases Is set. In this case, since the right steering is performed, the detected torque value T becomes a positive value, and therefore
The motor current command value S _I set from is also a positive value.

Then, based on the set motor current command value S _I and the motor current detection value i from the current detection circuit 66, predetermined processing is performed to calculate the motor drive signal S _M ,
The direction of rotation is determined based on the sign of the motor drive signal S _M ,
In this case, since S _M ≧ 0, the pulse width modulation signal PWM outputs a pulse signal corresponding to the motor drive signal S _M , and the direction signal as positive rotation.

On the other hand, the rotor position detection circuit 68 receives the sensor signals from the respective phase detection elements 31a to 31e, and FIG.
A combination of detection states of the corresponding sensor signals is obtained based on the gate setting table T1. At this time, for example, assuming that the rotor 27 is in the state of the section (1) in FIG. 5, the sensor signals Sa to Se of the respective phase detection elements 31a to 31e are (Sa, Sb, Sc, Sd, S) under normal conditions.
e) = (H, H, L, H, L), which corresponds to section (1) in the gate setting table T1,
The gate signals are (Ga1, Gb1, Gc1, G
d1, Ge1) = (1,1,0,0,0), and the lower side is (Ga2, Gb2, Gc2, Gd2, Ge2) = (0,
0,1,1,0), and this is the gate signal G
It is output to the FET gate drive circuit 62 as a1 to Ge2.

In the FET gate drive circuit 62, since the direction signal is a positive rotation, the transistors Ta1, Tb1, Tc2 and Td2 of the motor drive circuit 64 are kept at a predetermined level while the pulse width modulation signal PWM is "H". Supply voltage. As a result, in the coil circuit 35, a current flows from the outer end side to the exciting coils 26a and 26b, and a current flows from the connecting side to the exciting coils 26c and 26d. The S pole is generated, and therefore, the rotor 27 is rotated by the magnetic attraction force and the repulsive force between the N or S pole of the rotor 27 and the N or S pole generated in the convex portion.

Then, the rotor 27 rotates and the sensor signals Sa to Se of the phase detecting elements 31a to 31e change to (S
a, Sb, Sc, Sd, Se) = (H, L, L, H,
L), this corresponds to the section (2) in the gate setting table T1, so that the gate signal is (Ga1, Gb1, Gc1, Gd1, Ge1) = (1,
1,0,0,0), the lower side is (Ga2, Gb2, Gc
2, Gd2, Ge2) = (0,0,0,1,1) is output to the FET gate drive circuit 62. Therefore, a current flows through the exciting coils 26a and 26b from the outer end side, and a current flows through the exciting coils 26d and 26e from the connection side,
N poles and S poles are generated on a predetermined convex portion of the stator 26, and the rotor 27 further rotates. By repeating this operation, the rotor 27 continuously rotates, and the pulse width modulation signal P
The current supplied to the motor 12 is controlled according to WM,
The rotation of the motor 12 is controlled according to the magnitude of the detected torque value T, and the rotational driving force of the motor 12 is transmitted as the steering assist force of the wheel steering 2, so that the driver can easily perform the steering operation.

FIG. 9 shows that each exciting coil 26a is supplied with a constant current based on the exciting direction and exciting period of each phase shown in FIG.
Torque Ta generated in each phase when ~ 26e is excited ~
The solid line represents the total torque ZT, which is the sum of Te and the torque of the five phases, and the broken lines represent that the torques Ta to Te are not excited. And then, as mentioned above,
In (1), since the exciting coils 26a to 26d are excited,
The sum of these torques Ta to Td becomes the total torque ZT,
Similarly, in the section (2), the exciting coils 26a, 26b, 26
Since d and 26e are excited, the sum of these torques becomes the total torque ZT. Since the four exciting coils that are excited in the sections (1) and (2) have the same size, if the total torque ZT in the section (1) is ZT = Tα,
The total torque ZT in the section (2) is also Tα, and the total torque ZT in each section is constant at Tα.

Next, for example, if the rotor 27 is in the section of FIG.
In the state of (1), for example, assume that an abnormality occurs in the phase detection element 31a and the sensor signal thereof is fixed to "H" regardless of the rotational position of the rotor 27. In this case, as shown in the gate setting table T1 of FIG. 6, when the phase detection element 31a is normal, the phase detection element 31a
The sensor signal of “a” is “H” during the interval (1) to (5) in FIG.
Therefore, even if an abnormality has occurred, it is the same as that in the normal state, so the rotor position detection circuit 68 cannot detect that an abnormality has occurred, but it has no effect on the rotation of the motor 12. Then, when the rotor 27 rotates and enters the state of the section (6) of FIG. 5, each sensor signal Sa-
If Se is normal, (Sa, Sb, Sc, S
d, Se) = (L, L, H, L, H) should be set to (H, L, H, L, H). Therefore, in the control circuit 60, the rotational position of the rotor 27 is changed. Section (5) in Figure 5
Therefore, the same gate signal as the previous time is output to the FET gate drive circuit 62.

Therefore, the exciting coils 26a to 26 are originally provided.
d must be excited, but the excitation coil 26
Since a and 26c to 26e are excited, the torque generated by the exciting coil 26e becomes the negative side, that is, the torque acting in the direction opposite to the steering torque, as indicated by the alternate long and short dash line in FIG. , The total torque ZT becomes smaller, but the total torque ZT is the negative torque, that is,
There is no problem because the torque does not act in the opposite direction to the steering torque T.

Then, the rotor 27 rotates further and the
In the state of the section (7) of, the sensor signal is (Sa, S
b, Sc, Sd, Se) = (H, H, H, L, H), and this combination is the gate setting table T1 of FIG.
Since the states (1) to (10) are not present, the control circuit 60 is notified that the abnormal signal is "1", that is, the sensor signal is abnormal, and the gate signals Ga1 to Ge2 are all set to "0". Output. Therefore, the control circuit 60 outputs the relay control signal S _R as “LOW” to the relay drive circuit 70, which causes the relay drive circuit 70 to output the coil 70L.
Fail relay 70a by stopping excitation to
Is opened and the motor drive circuit 64 is de-energized,
In the FET gate drive circuit 62, all the transistors are turned off. Therefore, the driving of the motor 12 is stopped.

Therefore, when any one of the five sensor signals becomes abnormal, the section excited by an incorrect combination of exciting coils due to the abnormal sensor signal and the exciting coil The maximum deviation from the original section excited by the combination is 1 section, and when the exciting section (hereinafter referred to as the excitation section) is shifted by 1 section, the total torque ZT is the torque acting in the opposite direction. Therefore, there is no possibility that the steering operation cannot be locked and the abnormality can be detected during one rotation of the electrical angle even if the excitation section is deviated.
Anomaly detection can be performed before the lock state occurs.

Next, when the rotor 27 is in the state of the section (1) of FIG. 5, for example, the phase detection elements 31a and 31b are
Becomes abnormal, the sensor signal Sa is "H", the sensor signal S
It is assumed that b is fixed to "L". In this case, when it is normal, in the state of the section (1), as shown in the gate setting table T1 of FIG. 6, (Sa, Sb, S
c, Sd, Se) = (H, H, L, H, L) should be (H, H, L, H, L) as shown in section (1) ′ of FIG.
L, L, H, L), the rotor 27 in the control circuit 60 is a section in the gate setting table T1.
(2) That is, it recognizes that it is in the state of section (2) in FIG. 5, and outputs the gate signal in the state of section (2). Therefore, as shown by the alternate long and short dash line in FIG. 11, the excitation coils 26a, 26 are displaced by one section from the original excitation section.
Since b, 26d, and 26e are excited, the total torque ZT becomes smaller than the constant value Tα, but the torque is generated in the positive direction, so that the motor 12 can be rotated. Then, when the motor 12 rotates to the state of the section (2) of FIG. 5, the sensor signal has the normal section of the gate setting table T1 as shown in (2) ′ of FIG.
This is the same as the combination of the sensor signals of (2), so that a predetermined torque Tα can be generated.

As shown in the sections (3) 'to (5)' in FIG. 10, the section (3) to (5) in FIG. 5 is similar to the combination of the sensor signals in the normal state. A predetermined total torque ZT is generated to rotate the motor 12, and then the section (6) in FIG.
When it is in the normal state, (Sa, S
b, Sc, Sd, Se) = (L, L, H, L, H), as shown in FIG. 10 (6) '.
Since (H, L, H, L, H) is the same as the section (5) of FIG. 6, the control circuit 60 recognizes that the state is the section (5) of FIG. I will end up. Therefore, the total torque ZT becomes smaller than the constant value Tα as described above, but since the torque generation directions are the same, the rotation can be continued.

Then, in the state of section (7) in FIG. 5,
Similarly in this case, the sensor signal is (7) ′ in FIG.
As shown in, the state is the same as that of the section (5) of the gate setting table T1, so that the control circuit 60 uses the rotor 27
Is in the state of the section (5) in FIG. 5, the same exciting coil is continuously excited, so that the total torque ZT is as shown in FIG.
Although the torque becomes smaller as indicated by the one-dot chain line in Fig. 1, the torque is not on the negative side, so that the lock state is not achieved. Then, the motor 12 continues to rotate, and as shown in FIG.
When the state of the section (8) is reached, as shown in (8) ′ of FIG. 10, the sensor signal combination does not correspond to the sections (1) to (10) of the gate setting table T1. Of the control circuit 60 can be detected at this point.
Is notified, and all the gate signals are output as "0" to stop the current supply to the coil circuit 35. Therefore, although the assisting force of the motor 12 is lost, the abnormality can be detected before the lock state is achieved.

As shown in FIG. 11, the total torque ZT becomes positive torque and the motor 12 is locked while the deviation between the original excitation section and the excitation section erroneously excited is up to two sections. However, if a section that is deviated from the original excitation section by 3 sections is excited, the total torque ZT becomes a negative value, so that a torque in the opposite direction to the steering torque acts on the steering shaft 2. It will be locked.

Therefore, when the two sensor signals become abnormal, the excitation sections are shifted by only two sections at the maximum, so that the locked state does not occur, and the electrical angle becomes abnormal after the abnormality occurs. Abnormality can be reliably detected during one rotation. Next, the rotor 27 becomes the section (1) in FIG.
When in the state of, for example, the phase detection elements 31b, 3
1c and 31d become abnormal, the sensor signal Sb is "H",
It is assumed that the sensor signal Sc is fixed at "L" and the sensor signal Sd is fixed at "H". In this case, the section of Figure 5
In the state of (1), as shown in the gate setting table T1, the combination of the detection states of the sensor signals in the normal state is the same, so that the rotor 27 operates in the same manner as in the normal state and rotates. Then, when the state of the section (2) in FIG. 5 is reached, in this case, when it is normal, (Sa, Sb, Sc, S
d, Se) = (H, L, L, H, L) should be (H, H, L, H, L), which is the same as the state in the section (1) in the control circuit 60. It is judged that it is a thing, and the same exciting coil as before is excited. Therefore, even if the total torque ZT smaller than the predetermined torque Tα is generated and the rotor 27 continues to rotate due to this, and the state of the sections (3) and (4) is reached, the combination of the sensor signals is the one of the section (1). Since it is the same as the state, the same exciting coil is excited in four sections.

As a result, as can be seen from FIG.
In the fourth section, the total torque ZT becomes a negative torque and a torque in the opposite direction to the steering torque is generated, but there is no problem because the rotor 27 can be rotated in about one section due to the inertia of the motor 12, When the rotor 27 rotates and enters the state of the section (5) in FIG. 5, an abnormality can be detected from the combination of the sensor signals at this point, and the current supply to the coil circuit 35 is stopped at this point. Then
Since the motor 12 is stopped, the steerability is not adversely affected. Further, when the three sensor signals become abnormal, the locked state is the sensor signals of three continuous phase detection elements, that is, (Sa, Sb, Sc),
Only when a combination of (Sb, Sc, Sd) and (Sc, Sd, Se) is abnormal in the detection state of (H, L, H) or (L, H, L). Since the possibility of occurrence of an abnormality is extremely low, there is no problem, and when an abnormality occurs in any other combination, it is possible to reliably detect the abnormality without being locked.

When there are four abnormal sensor signals, when there are four abnormalities in the order of Sa to Se, for example, (Sa, Sc, Sd, Se) or (Sa, S
b, Sd, Se) in that order, only when (H, L, H, L) or (L, H, L, H), the lock state is established and this cannot detect an abnormality, but at the same time 4 One of the detection signals becomes abnormal and the sensor signal is (H,
(L, H, L) or (L, H, L, H) is unlikely to be abnormal, so there is no problem.

Similarly, if all the sensor signals are abnormal and the same combination as the state of the sections (1) to (10) of the gate setting table T1 is abnormal, the state is locked and the abnormality can be detected. Although not, there is no problem because all sensor signals become abnormal and it is unlikely that an abnormality will occur in this combination. Therefore, according to the first embodiment, the 5-phase brushless motor is applied, and the phase detection element 31a is selected depending on whether the combination of the detection signals of the phase detection elements 31a to 31e is a preset combination pattern. It is possible to easily detect the abnormality of the detection signals of ~ 31e, and it is possible to reliably detect the abnormality without the 5-phase brushless motor being locked except that the abnormality occurs in a specific pattern. Further, since the probability that an abnormality occurs in the specific pattern is very small, there is no problem, and the reliability can be further improved as compared with the case of using a three-phase brushless motor.

Further, since there is no abnormality in the motor 12 itself, it suffices to stop the supply current to the motor when an abnormality is detected without providing an electromagnetic clutch, and to assist by stopping the supply current to the motor. There is no influence on the wheel steering operation only by the loss of force. In the first embodiment, the current supply to the motor 12 is stopped when an abnormality is detected. For example, when the abnormality is detected, the current supplied to the motor 12 is smaller than the actual motor drive current value. Is supplied to the motor 12 to reduce the assist force.
It is also possible to prevent the wheel steering operation from being disabled even when the assist force is generated in the direction opposite to the steering direction.

Next, a second embodiment of the present invention will be described. The second embodiment has the same device configuration as that of the first embodiment. The control circuit 60 corresponds to the motor control means,
The FET gate drive circuit 62 and the motor drive circuit 64 correspond to the drive circuit, and the rotor position detection circuit 68 corresponds to the excitation control means, the abnormality processing means, and the motor stop means.

In the first embodiment, even if one sensor signal becomes abnormal, the control circuit 60 is notified that an abnormality has occurred, and the generation of the assisting force on the steering shaft 2 by the motor 12 is stopped. Is done,
In the case of the first embodiment described above, the motor 12 is immediately immediately after the occurrence of the abnormality
Is not locked and the torque fluctuation of the motor 12 becomes large and the steering operation is not smooth, but assisting is possible. This assist force makes it possible to make the steering operation lighter than when the motor 12 is not operated at all, and it is possible to prevent the assist force from suddenly disappearing during steering due to the occurrence of an abnormality. Even if an abnormality occurs in the sensor signal, the motor 12 is operated as much as possible unless the motor 12 is locked.

According to the first embodiment, three or more sensor signals adjacent to each other in the order of the sensor signals Sa to Se become abnormal, and two of these signals are fixed to "H" and "L". It is understood that the motor 12 is in the locked state when it is turned on. Therefore, in consideration of this, FIG. 12 shows that the combination of occurrence of abnormal signals is set. In the figure,
(A) is a combination of sensor signals in which the motor 12 is not locked, (B) is a combination of sensor signals that may be in a locked state but can detect an abnormality,
(C) is a combination of sensor signals that cannot detect an abnormality because it may be in a locked state, “x” notifies the abnormality and stops the assist by the motor 12, and “continue” does not notify the abnormality and assists Represents continuing.

In FIG. 12, when one sensor signal becomes abnormal, the assist is stopped when the sensor signal is fixed at "H", and the assist is continued when it is fixed at "L". , The sensor signal becomes more abnormal 2
When the second sensor signal is fixed to "H" and becomes abnormal, the assist is stopped, and when it is fixed to "L" and abnormal, the assist is continued, and so on. When it is fixed to "H", the assist is stopped at all times, and when it is fixed to "L" and there is an abnormality, the assist is continued and all five sensor signals are "L".
When it is fixed to and becomes abnormal, the assist is stopped.

Here, for example, when the sensor signal is fixed to "H" and becomes abnormal, the motor 12 does not enter the lock state, but the assist is stopped. Avoids that when three or more sensor signals are fixed to "H" and "L" and becomes abnormal, there is a possibility that it will be in a locked state and the occurrence of abnormality cannot be detected in some cases. In order to do so, when the abnormality is fixed to “H”, the abnormality is always notified and the assist is stopped. In the case of FIG. 12, the abnormality notification is made when the abnormality is fixed to “H”, but in FIG. 12, the combination of the sensor signals that generate the abnormality signal is “H”.
It is also possible to completely reverse "L" and "L", and when it is fixed to "L" and an abnormality occurs, an abnormality notification is given and the assist is stopped.

The gate setting table T2 in FIG. 13 shows the correspondence between the combination of sensor signals and the abnormal signal to be set based on FIG. Then, as in the first embodiment, the rotor position detection circuit 68 combines, for example, a combination of the detection states of the sensor signals in the normal state in advance with the gate signals of the upper stage side and the lower stage side to be excited in this combination. A normal table representing the correspondence is formed and stored, and the gate setting table T2 is referred to based on the combination of the detection states of the input sensor signals to find the corresponding combination, and the specified abnormal signal is output. In addition, when the obtained combination of sensor signals is the combination of the detection states of the sensor signals set in the normal table, the upper and lower gate signals set in the normal table are output to set the gate. The abnormal signal designated by the table T2 is output. Then, when the combination of the detection states of the input sensor signals is different from the preset combination of the detection states of the normal sensor signals, all the gate signals are output as zero.

For example, in the state where right steering is being performed,
It is assumed that when the rotor 27 is in the state of the section (1) of FIG. 5, an abnormality occurs in the phase detection elements 31a and 31b, and the sensor signals Sa and Sb are both fixed to “L” and become abnormal. Originally, the sensor signal at this time is (Sa, Sb, S) as shown in the gate setting table T1 of FIG.
c, Sd, Se) = (H, H, L, H, L), but since the sensor signals Sa and Sb are abnormal,
As shown in (1) ″ of FIG. 4, (L, L, L, H, L) is obtained, which corresponds to the gate setting table T2 in FIG.
Corresponds to "30". Therefore, the abnormal signal is output as "0", and the gate signals Ga1 to Ge2 are all "0".
Output as As a result, the current supply to the coil circuit 35 is stopped. Similarly, when the state of the section (2) of FIG. 5 is reached, the sensor signal becomes (2) ″ of FIG. 14 and similarly corresponds to “30” of FIG. 13, so that current supply to the coil circuit 35 is performed. No. Similarly, sections (3), (4), and
Between (8) to (10) are (3) ″, (4) ″, (8) ″ to (10) ″ in FIG.
As shown in, the abnormality is not notified, but the current is not supplied to the motor 12.

Then, the sections (5) to (7) in FIG.
As shown in (5) ″ to (7) ″ of FIG. 4, it corresponds to “27” of the gate setting table T2 of FIG. 13, and this corresponds to (6) of the gate setting table T1 of FIG. During this time, the exciting coils 26a to 26d are excited, and when in the state of the section (6) in FIG. 5, the predetermined exciting coil in the normal state is excited, so that the predetermined torque Tα can be generated,
In the sections (5) and (7) of (1), since the excitation section is only shifted by one section, it is possible to generate a torque in the plus direction, which is smaller than the torque Tα.

Therefore, torque can be generated and assist can be performed during the sections (5) to (7) in FIG. 5, so that the assist force is prevented from suddenly disappearing during the steering operation. In addition, the driver can easily perform the steering operation as compared with the case where no assist is performed. Further, according to the second embodiment described above, since the abnormality notification is made when the combination becomes the locked state, it is possible to reliably prevent the locked state. Therefore, it is possible to reliably prevent the steering operation from becoming impossible due to the locked state.

Further, according to the second embodiment, even if one sensor signal becomes abnormal, if the motor 12 is not in the lock state, the abnormality notification is not sent to the control device 60, so that the torque fluctuation is not generated. Although a little uncomfortable during steering operation, the assist force can be effectively generated and the motor 12 can be utilized to the maximum extent. At this time, although the abnormality notification is not issued, the driver can recognize that the assist force has decreased by performing the steering operation, and thus can recognize that an abnormality has occurred in the sensor signal.

Therefore, according to the first and second embodiments, since the brushless motor is used as the assist drive source, an abnormality occurs in the motor due to abrasion of the brush as in the conventional brushed motor. The probability is low, and the reliability can be further improved as compared with the conventional electric power steering apparatus using the brushed motor.

Further, in the first and second embodiments, since the 5-phase brushless motor is applied, the rotor can be made thinner as compared with the brushed motor which has been conventionally applied. Therefore, The inertia acting on the rotor can be made smaller. Further, since the brushless motor has no brush, it is possible to avoid energy loss due to the brush.

Further, in the first and second embodiments, since the reliability of the motor is high and the probability of occurrence of abnormality is very small, the electromagnetic clutch device for transmitting / disconnecting the assist force of the motor as in the prior art. Need not be provided. Therefore, the electromagnetic clutch device is expensive and has problems such as heavy weight and influence on inertia, but these problems can be avoided.

In the first and second embodiments, the case where the right steering is performed has been described. However, even when the left steering is performed, the gate signal Ga in the FET gate drive circuit 62 is changed.
It is possible to obtain the same effect as the above except that the processes for 1 to Ge2 are different. Further, in the first and second embodiments, the case where five phase detection elements 31 are arranged at equal intervals in the circumferential direction of the rotor 27 has been described, but for example, five phase detection elements 31 are provided at equal intervals in 120 degrees in the circumferential direction. It is also possible to arrange them individually.

In the first and second embodiments, the case where the permanent magnet 28 is magnetized with three S poles and three N poles alternately in the circumferential direction and at equal intervals, that is, a total of six poles is described. However, not limited to this, if the combination of the sensor signals in each section of FIG. 5 is the same as the combination of the sensor signals of the gate setting table T1 or T2, it is possible to magnetize an arbitrary number of poles.

Further, in the first and second embodiments, the case where the FET (field effect transistor) is used as the switching element of the motor drive circuit 64 has been described. However, the present invention is not limited to this, and other types such as a bipolar transistor may be used. It is also possible to apply a switching element. In addition, in the first and second embodiments, when the rotor position detection circuit 68 gives an abnormality notification, the control circuit 60 sets the fail relay 70a in the open state to stop the energization of the motor drive circuit 64 to turn on the motor 12. However, it is also possible to stop the output of the pulse width adjustment signal PWM from the control circuit 60, for example.
Further, it is also possible to forcibly fix all the transistors Ta1 to Te2 to the off state or to forcibly fix all the transistors Ta1 to Te1 to the off state to stop the driving of the motor 12.

In the first and second embodiments, the PI
Although the case where the drive control of the motor 12 is performed by the D control has been described, the control is not limited to this, and the control may be performed by the PI control, the P control, or the like. Further, in the first and second embodiments, the case where the motor current command value is set based on the steering torque and the vehicle speed has been described. However, for example, the motor current command value is set based only on the steering torque. It is also possible to set.

In the first and second embodiments described above, the case where the control circuit 60 and the rotor position detection circuit 68 are formed by a microcomputer has been described, but the present invention is not limited to this, and an arithmetic circuit, an addition circuit, a logic circuit, etc. It is also possible to configure by combining the electronic circuits of. Further, in the first and second embodiments, the motor drive control for detecting the steering state based only on the detected torque value and generating the auxiliary steering torque according to the detected torque value has been described.
In addition to this, for example, when changing the traveling lane during high-speed traveling, in addition to the steering torque, the steering state is detected according to the steering angular velocity and the steering angular acceleration of the steering wheel, and the steering state is detected according to these values. It is also possible to generate an auxiliary torque and perform motor drive control.

[0085]

According to the electric power steering apparatus of the first aspect, whether or not there is a combination corresponding to the position detection state of the five position detection signals from the phase detection element of the five-phase brushless motor on the table. Therefore, the abnormality of the position detection signal can be detected easily and surely, and when there is no combination corresponding to the position detection state of the position detection signal on the table, the motor restraining means reduces the steering assist force by the 5-phase brushless motor. Since the generation is stopped, even if an abnormality occurs in the position detection signal, it is possible to reliably prevent the steering operation from becoming impossible.

Further, according to the electric power steering apparatus of the second aspect, the position is easily and surely determined depending on whether or not the combination corresponding to the position detection state of the five position detection signals from the phase detection element is on the table. The abnormality of the detection signal can be detected, and when there is no combination corresponding to the position detection state of the position detection signal in the table, the abnormality processing means stops the current supply to the 5-phase brushless motor to stop the generation of the steering assist force. Then, the drive of the 5-phase brushless motor is stopped by the motor stopping means only when the combination of the position detection states of the position detection signals is a combination in which the steering assist force in the direction opposite to the steering direction of the steering wheel is generated from the 5-phase brushless motor. After that, the steering assist force is not generated, and even if an abnormality occurs in the position detection signal, As long as the steering assist force in the direction it is not generated can be effectively generated steering assist force to drive the 5-phase brushless motor steering system.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of a 5-phase brushless motor.

FIG. 3 is a block diagram showing an example of an electric power steering device according to the present invention.

FIG. 4 is a development view of windings of a stator.

FIG. 5 is a waveform diagram of an exciting current.

FIG. 6 is a configuration diagram of a gate setting table T1 in the first embodiment.

FIG. 7 is a flowchart showing an example of a processing procedure of motor drive control processing in a control circuit.

FIG. 8 is a characteristic diagram showing a relationship between a steering torque and a motor current value with a vehicle speed as a parameter.

FIG. 9 is a torque generation diagram provided for explaining the operation of the first embodiment.

FIG. 10 is a combination of sensor signals used for explaining the operation of the first embodiment.

FIG. 11 is a torque generation diagram provided for explaining the operation of the first embodiment.

FIG. 12 shows a combination of occurrences of abnormal signals in the second embodiment.

FIG. 13 is a gate setting table T2 in the second embodiment.
FIG.

FIG. 14 is a combination of sensor signals used for explaining the operation of the second embodiment.

FIG. 15 is an explanatory diagram showing a correspondence between a conventional sensor signal and a gate signal.

FIG. 16 is an explanatory diagram for explaining the conventional operation at the time of abnormality.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steering wheel 3 Torque sensor 12 Motor (5-phase brushless motor) 13 Controller 16 Battery 17 Vehicle speed sensor 24 Rotating shaft 25 Permanent magnet 26 Stator 26 'Stator core 26a to 26e Excitation coil 28 Permanent magnet 31 (31a to 31e) Phase detection element 35 coil circuit 60 control circuit 62 FET gate drive circuit 64 motor drive circuit 66 current detection circuit 68 rotor position detection circuit 70 relay drive circuit

Claims (2)

[Claims] 1. A steering assist force is generated for a steering system.
Phase brushless motor, five phase detection elements for detecting the rotational position of the rotor of the five-phase brushless motor, a combination of the position detection state of the position detection signal of the phase detection element at the normal time, and the five-phase brushless motor Excitation control means for holding an excitation coil to be excited and designating an excitation coil corresponding to the position detection state of the position detection signal by referring to the table, and the steering system from the 5-phase brushless motor A motor control means for outputting a control signal for generating a steering assist force, and a drive for controlling the energizing direction and the energizing amount to the exciting coil designated by the exciting control means based on the control signal from the motor controlling means. Circuit, the excitation control means, when there is no combination corresponding to the position detection state of the position detection signal in the table, the excitation control means, Electric power steering apparatus comprising: a motor inhibiting means inhibits driving of Resumota. 2. A steering assist force is generated for a steering system.
Phase brushless motor, five phase detection elements for detecting the rotational position of the rotor of the five-phase brushless motor, a combination of the position detection state of the position detection signal of the phase detection element at the normal time, and the five-phase brushless motor Excitation control means for holding an excitation coil to be excited and designating an excitation coil corresponding to the position detection state of the position detection signal by referring to the table, and the steering system from the 5-phase brushless motor A motor control means for outputting a control signal for generating a steering assist force, and a drive for controlling the energizing direction and the energizing amount to the exciting coil designated by the exciting control means based on the control signal from the motor controlling means. A circuit, the excitation control means is configured to control all the excitation coils when there is no combination corresponding to the position detection state of the position detection signal in the table. And abnormality processing means for canceling the designation of Le, the combination of the position detection state of the position detection signal,
Electric power comprising: a motor stop means for stopping the drive of the 5-phase brushless motor when the combination is such that the 5-phase brushless motor generates a steering assist force in a direction opposite to the steering direction of the steering wheel. Steering device.