JP2000270583A - Motor-driven power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a motor-driven power steering device which can drive a brushless motor with a timing corresponding to a leading angle which copes with a load and can reduce torque ripples of the brushless motor to improve sensation of steering. SOLUTION: A motor-driven power steering device is attached as the steering device of operation wheels, such as front wheels of a motor vehicle. The operation wheels are steered by an auxiliary steering force given by a brushless motor and a manual steering force given by a steering wheel. The control circuit unit 4 of the brushless motor is connected to the brushless motor 1, a torque sensor 6, load sensors which detect with timings corresponding to different leading angles respectively, i.e., a CW low load sensor 8, a CW high- load sensor 9, a CCW low-load sensor 10 and a CCW high load sensor 11, etc. According to when a load is low or high, one of the signals of the low load sensor 8 (10) or of the high load sensor 9 (11) is selected and controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensing technique for an electric power steering apparatus for a vehicle, and more particularly to a technique for driving a brushless motor for an electric power steering at a timing corresponding to an optimum advance angle according to a load. The present invention relates to a technology that is effective when applied to a possible electric power steering device.

[0002]

2. Description of the Related Art For example, as a technique studied by the present inventor, an electric power steering apparatus is mounted as a steering apparatus for a steering wheel such as a front wheel of an automobile, and its performance is changed by changing how a brush hits a commutator. A brushless motor has come to be used in consideration of no change, a long life, and the like. As an electric power steering apparatus using this brushless motor, a so-called rack assist type in which a brushless motor is provided coaxially with a rack shaft and a steering assist force is obtained by a brushless motor provided on the rack shaft. Are known.

In this rack assist type electric power steering apparatus, a brushless motor, a rack shaft provided coaxially with the brushless motor, and a rack-and-pinion connection via a coupling mechanism with the rack shaft. It consists of a steering wheel, a steering wheel and the like, and transmits a steering assist force generated by a brushless motor to a rack shaft via a ball screw mechanism. The steering wheel is steered by the steering assist force of the brushless motor and the manual steering force by operating the steering handle, so that the driver's steering load can be reduced (for example, Japanese Patent Laid-Open No. 8-11).
No. 9132).

[0004]

In the electric power steering apparatus using the brushless motor, commutation control of the brushless motor is performed according to position detection information of a rotor. The torque ripple increases, and the torque ripple is transmitted to the driver via the handle shaft as backlash of the steering wheel, which may adversely affect the steering feeling of the driver.

Accordingly, an object of the present invention is to focus on an electrical advance related to the torque ripple of a brushless motor,
It is an object of the present invention to provide an electric power steering apparatus that drives a brushless motor at a timing corresponding to an advance angle corresponding to a load, reduces torque ripple of the brushless motor, and improves steering feeling.

[0006]

SUMMARY OF THE INVENTION An electric power steering apparatus according to the present invention includes a brushless motor for generating a steering assist force, and a coil for each phase of the brushless motor.
A drive unit that rotates the brushless motor in a predetermined direction by de-energizing, a load detection unit that detects a load applied to the brushless motor, and a plurality of units that detect the position of the rotor of the brushless motor at timings corresponding to different advance angles. Of the plurality of position detecting means and the plurality of position detecting means
A detection signal of one position detection means of the brushless motor is selected according to the load detected by the load detection means, and a driving means is controlled based on the detection signal of the selected position detection means, and each phase of the brushless motor is controlled. And control means for controlling the energization / non-energization time of the coil at a timing corresponding to a predetermined advance angle.

Therefore, according to the electric power steering apparatus, the brushless motor can be controlled by selecting and controlling the detection signals of the position detecting means for detecting the timings corresponding to different advance angles according to the load. Since the brushless motor can be driven at a timing corresponding to an optimum advance angle according to the load, the torque ripple rate during rotation of the brushless motor can be reduced to prevent backlash occurring in the steering wheel, and according to the load. By selecting the advance angle, the output efficiency at the time of a high load can be improved, a sufficient steering assist force can be obtained, and the steering feeling can be improved over the entire range from a low load to a high load.

Further, another electric power steering apparatus according to the present invention is characterized in that the brushless motor, the driving means, and the load detecting means, and a position detecting means for detecting a position of a rotor of the brushless motor at a predetermined timing. A timing signal corresponding to a predetermined advance angle is generated based on a detection signal of the position detection means of the brushless motor in accordance with the load detected by the load detection means, and the driving means is controlled by the timing signal to control each phase of the brushless motor. And control means for controlling the energization / non-energization time of the coil at a timing corresponding to a predetermined advance angle.

Therefore, according to the electric power steering apparatus, the brushless motor is controlled by generating and controlling a timing signal corresponding to a predetermined advance angle based on the detection signal of the position detecting means according to the load. Since the brushless motor can be driven at a timing corresponding to an optimum advance angle according to the load, the torque ripple rate during rotation of the brushless motor can be reduced to prevent backlash occurring in the steering wheel, and according to the load. By selecting the advance angle, the output efficiency at the time of a high load can be improved, a sufficient steering assist force can be obtained, and the steering feeling can be improved over the entire range from a low load to a high load.

For example, the present inventor simulates the relationship between the lead angle and the torque ripple corresponding to each load. FIG. 8 shows a torque ripple waveform diagram at a low load (sensor position: lead angle 0 degree). , FIG. 9 shows a torque ripple waveform diagram at low load (sensor position: advance angle 7 degrees), FIG.
Description will be made based on a characteristic diagram showing the relationship between the advance angle and the torque ripple shown in FIG.

As shown in FIG. 8, when the load is low, the rise of the torque ripple waveform at the sensor position of 0 degree is steeper than the ideal torque ripple waveform, and the switching is slow. On the other hand, as shown in FIG. 9, since the falling of the torque ripple waveform with the sensor position of the advanced angle of 7 degrees becomes steep, it can be understood that the switching is too early. FIG. 10 shows the relationship between the lead angle and the torque ripple rate corresponding to each load (motor current) in consideration of the result of the simulation at a low load and the load at a high load.

Generally, the steering feeling is determined to be good when the torque ripple rate is equal to or less than a certain value (the reference line in FIG. 10). In FIG. 10, for example, when the motor current is small and the load is low, the advance angle at which the torque ripple ratio becomes the smallest below the reference line is a degree. The advance angle at which the ratio becomes the smallest is b degrees, and therefore, it is considered ideal to increase the advance angle as the load shifts from the low load side to the high load side. Therefore, the present invention applies this characteristic to the control of a brushless motor for electric power steering.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. In all the drawings for describing the embodiments, the same members will be denoted by the same reference numerals, and members having similar functions will be denoted by the same reference numerals with lowercase alphabetic characters. Omitted.

(Embodiment 1) FIG. 1 is a schematic configuration diagram showing a main part of an electric power steering apparatus according to Embodiment 1 of the present invention, and FIG. FIG. 3 is a functional block diagram illustrating a control circuit unit of the brushless motor.
FIG. 4 is a timing chart showing the operation of the control circuit of the brushless motor.

First, a schematic configuration of an example of the electric power steering apparatus according to the first embodiment will be described with reference to FIG.

The electric power steering apparatus according to the first embodiment is mounted as a steering apparatus for a steering wheel such as a front wheel of an automobile, and includes a brushless motor 1 and a rack shaft provided coaxially with the brushless motor 1. 2
A steering wheel (not shown) connected to both ends of the rack shaft 2 via a connecting mechanism such as a rod and an arm; and a steering wheel connected to the rack shaft 2 via a connecting mechanism such as a steering shaft. The steering system includes a handle 3, a control circuit unit 4 for controlling the driving of the brushless motor 1, a ball screw driving unit 5 for transmitting a steering assist force generated by the brushless motor 1 to the rack shaft 2, and the like. The steered wheels are steered by the force and the manual steering force by operating the steering handle 3.

The brushless motor 1 of the electric power steering apparatus includes a torque sensor 6 provided between the steering handle 3 and the rack shaft 2 and a sensor unit 7 for detecting the position of the rotor of the brushless motor 1. It is controlled via the control circuit unit 4 based on the detection result. The brushless motor 1 is, for example, an inner rotor type, in which a stator is disposed on an outer peripheral portion and a rotor is provided on an inner peripheral portion. A three-phase coil is held on the inner periphery of the stator, and a magnet is arranged on the outer periphery of the rotor.

In particular, the sensor section 7 of the brushless motor 1 is provided with four sensors 8 to 11 shifted from each other in the rotation direction of the rotor of the brushless motor 1 as shown in an example in FIG. The four sensors in each set are a CW (clockwise) low load sensor 8, a CW high load sensor 9, and a CCW (counterclockwise) low load sensor 1, respectively.
0, assigned as CCW high load sensor 11. That is, in the relationship between the lead angle corresponding to the load and the torque ripple rate shown in FIG. 10, for example, the low load sensors 8 and 10 have a lead angle of about 3.5 degrees and the high load sensor 9 as an example. , 11 are arranged at positions corresponding to a lead angle of about 7 degrees.

Next, an example of the configuration of the control circuit section 4 of the brushless motor 1 will be described with reference to FIG.

The control circuit 4 of the brushless motor 1
Represents three of the U phase, V phase and W phase, which have been schematically described above.
Brushless motor 1 having a phase coil and generating a steering assist force, and a torque sensor 6 serving as load detecting means for detecting a load (steering torque) applied to the brushless motor 1
And four CW low load sensors 8 and CW high load sensors 9 which are four position detecting means for detecting the position of the rotor of the brushless motor 1 at timings corresponding to different advance angles of each set of each coil. , CCW low load sensor 1
0, connected to the CCW high load sensor 11 and the like.

The control circuit section 4 includes a brushless motor 1
Energizing / de-energizing the coils of each phase of
Gate circuit 12 and three sets of FET1 to FET6 as driving means for rotating the sensor in a predetermined direction, and among the four sensors 8 to 11, among the four sensors 8 to 11 according to the load detected by the torque sensor 6. A detection signal of one of the sensors 8 (or any one of 9, 10, 11) is selected, and based on the selected detection signal, the FET gate circuit 12 is controlled, and energization / non-energization of coils of each phase is selected. The control circuit 13 (control means) for controlling the time so as to have a predetermined duty at a timing corresponding to a predetermined advance angle is provided. The detection signal is selected by a rotor position signal selection circuit 14, which outputs a signal for switching FET1 to FET6, and a control circuit 13 which outputs a drive duty signal.

Each of the three sets of FET1 to FET6 has its gate connected to the FET gate circuit 12, and turns ON / OF based on the drive duty and the FET switching signal.
F is controlled. The drain of the FET1 is connected to the power supply voltage, the source is connected to the drain of the FET4, the source is connected to the ground voltage via the current detection circuit 15, and the brushless motor is connected from the connection node between the source of the FET1 and the drain of the FET4. It is connected to the U phase of one coil. Similarly, FET2 and FET5, FET3 and FE
T6 is also connected between the power supply voltage and the ground voltage, and is connected from each connection node to the V-phase and W-phase of the coil of the brushless motor 1. These three sets of FET1 to FET6 are
The N / OFF control and the commutation control of the current flowing through each phase coil allow the brushless motor 1 to rotate clockwise and counterclockwise.

Next, regarding the operation of the first embodiment, the operation of the control circuit unit 4 of the brushless motor 1 will be described with reference to FIG.

Here, when one of the detection signals of the CW low load sensor 8 and the CW high load sensor 9 corresponding to each phase of the coil of the brushless motor 1 is selected, and the brushless motor 1 is rotated clockwise. Is shown. At this time, CW
The switching between the low-load sensor 8 and the CW high-load sensor 9 is performed by a driving current based on an input from the torque sensor 6. The actual current flowing through the brushless motor 1 is detected by a current detection circuit 15, and the detected actual current is detected. It is also possible to detect the load based on the current and switch between the CW low load sensor 8 and the CW high load sensor 9. Further, the rotation direction of the brushless motor 1 is determined by the input value from the torque sensor 6 depending on which force is applied.

For example, when the driving current by the input from the torque sensor 6 is small, that is, when the steering torque is small and the load is low, the rotor position signal selection circuit 14 corresponds to the U-phase, V-phase and W-phase of the coil of the brushless motor 1. C
The detection signal from the W low load sensor 8 is selected. At this time, the detection signals HU1, HU from each CW low load sensor 8 are used.
V1 and HW1 have waveforms whose ON / OFF timings are sequentially shifted from HU1 to HV1 to HW1 at a predetermined timing.

Then, each detection signal HU1, HV1, HW
1, the rotor position signal selection circuit 14
A switching signal is output to control the FET gate circuit 12 to switch between FET1 to FET6. At the same time, the control circuit 13 controls the energization / de-energization time of the U-phase, V-phase, and W-phase of the coil so as to have a predetermined duty at a timing corresponding to a predetermined advance angle. At this time, FETs 1 to F
In ET6, the ON / OFF timing is F in order.
ET1 → FET2 → FET3, FET4 → FET5 →
The waveform is shifted to the FET 6 at a predetermined timing.

That is, ON / OFF of the FET1 is controlled by a waveform which rises at the falling edge of the detection signal HU1 and falls at the falling edge of the detection signal HV1. Similarly, ON / OFF of FET2 (FET3)
Is controlled by a waveform that rises at the falling edge of the detection signal HV1 (HW1) and falls at the falling edge of the detection signal HW1 (HU1). In addition, O of FET4
N / OFF is controlled by a waveform that rises at the rising edge of the detection signal HU1 and falls at the rising edge of the detection signal HV1. Similarly, FET5 (FET6)
Is controlled by a waveform that rises at the rising edge of the detection signal HV1 (HW1) and falls at the rising edge of the detection signal HW1 (HU1).

As a result, in the U-phase, V-phase and W-phase of the coil of the brushless motor 1, the U-phase coil is
Is turned on, a positive current is supplied when the FET 4 is ON, and a negative current is supplied when the FET 4 is ON. Similarly, the V-phase (W-phase) coil has a positive current when the FET2 (FET3) is ON,
When ET5 (FET6) is ON, it is supplied with a negative current and is excited. By controlling the commutation of the current flowing through the U-phase, V-phase, and W-phase coils, the brushless motor 1
Can be rotated clockwise at a timing corresponding to an optimum advance angle (for example, about 3.5 degrees) corresponding to a low load.

On the other hand, when the driving current due to the input from the torque sensor 6 is large, that is, when the steering torque is large and the load is high, the rotor position signal selection circuit 14 corresponds to the U phase, V phase and W phase of the coil of the brushless motor 1. The detection signal from the CW high load sensor 9 is selected. At this time,
Detection signals HU2, HV from each CW high load sensor 9
2 and HW2, the ON / OFF timings are sequentially shifted from HU2 → HV2 → HW2 at a predetermined timing, respectively.
In addition, the waveform is advanced by α degrees (for example, 7−3.5 = about 3.5 degrees) compared to the detection signals HU1, HV1, and HW1.

Then, each detection signal H advanced by α degrees
Based on U2, HV2, and HW2, the rotor position signal selection circuit 14 outputs an FET switching signal to control the FET gate circuit 12, and controls the FET 1
To switch FET6. At the same time, the control circuit 13 sets the energization / de-energization time of the U, V, and W phases of the coil to α.
Control is performed so that a predetermined duty is obtained at a timing corresponding to a predetermined advance angle advanced by the degree.

As a result, the U phase, V
The phase and W-phase coils are energized and energized at a timing corresponding to a predetermined advance angle advanced by α degrees. Thus, the current flowing through the U-phase, V-phase, and W-phase coils is advanced by α degrees as compared with the low load state to perform commutation control, so that the brushless motor 1 has an optimum advance angle corresponding to a high load. (For example, about 7 degrees), it can be rotated clockwise at a timing corresponding to the timing.

In FIG. 3, the CW low load sensors 8, C corresponding to the respective phases of the coil of the brushless motor 1 are shown.
The case where one detection signal of the W high load sensor 9 is selected and the brushless motor 1 is rotated in the clockwise direction has been described, but one detection signal of the CCW low load sensor 10 and the CCW high load sensor 11 is The same applies to the case where the brushless motor 1 is selectively rotated in the counterclockwise direction.

Therefore, according to the first embodiment, the CW low-load sensor 8 (CCW low-load sensor 10) provided at a position corresponding to a small advance angle at low load and high load. One of the detection signals of the CW high-load sensor 9 (CCW high-load sensor 11) provided at a position corresponding to a large advance angle is selected, and the brushless motor 1 is driven at a timing corresponding to an optimum advance angle. As a result, the torque ripple during the rotation of the brushless motor 1 can be reduced, so that the steering feeling is improved. In particular, when the load is low, the steering feeling is remarkable. Can be.

(Embodiment 2) FIG. 5 is a functional block diagram showing a control circuit of a brushless motor in an electric power steering apparatus according to Embodiment 2 of the present invention. FIG. 6 is a block diagram of a control circuit of the brushless motor. FIG. 7 is a flowchart showing the processing, and FIG. 7 is a timing chart showing the operation of the control circuit section of the brushless motor.

The electric power steering apparatus according to the second embodiment is mounted as a steering apparatus for a steering wheel such as a front wheel of an automobile, similarly to the first embodiment, and includes a brushless motor 1, a rack shaft 2, a steering mechanism, and the like. Wheels, steering handle 3,
This embodiment includes a control circuit section 4a and the like. The difference from the first embodiment is that the first embodiment switches a sensor corresponding to a different advance angle in accordance with a load. The second embodiment is different from the first embodiment in that the commutation timing corresponding to the advance angle is calculated by a sensor signal.

That is, the control circuit section 4a of the brushless motor 1 of the second embodiment includes a brushless motor 1 and a torque sensor 6 (load) similar to those of the first embodiment, as shown in an example in FIG. Detection means) and two CW low load sensors 8 and CCW low load sensors 10 which are two position detection means for detecting the position of the rotor of the brushless motor 1 at a predetermined timing for each coil. . The low-load sensors 8 and 10 are arranged at positions corresponding to, for example, a lead angle of about 3.5 degrees, for example. The reason why the low-load sensors 8 and 10 are divided into those for CW and those for CCW is to advance the angle by a predetermined amount at the time of startup, and one low-load sensor 8 (or 1
0) alone is also possible.

The control circuit section 4a is provided in the first embodiment.
Gate circuit 12 and three sets of FET1
A predetermined advance angle based on a detection signal of the FET 8 and a sensor 8 (10) provided for each phase coil in accordance with the load (steering torque) detected by the torque sensor 6, which is different from that of the first embodiment. And the FET gate circuit 12 is controlled by the timing signal, and the energization / de-energization time of the coil of each phase is controlled to a predetermined duty at a timing corresponding to a predetermined advance angle. And a control circuit 13a (control means). The detection signal is input to the rotor position detection circuit 14a, and the drive duty and F
A signal for switching ET1 to FET6 is output.

Next, regarding the operation of the second embodiment, the processing of the control circuit unit 4a of the brushless motor 1 will be described with reference to FIG.
The operation of the control circuit unit 4a will be described with reference to FIG. This processing is performed in a software manner by a control circuit 13a including a CPU according to a predetermined algorithm.

First, as a main routine of FIG. 6A for controlling the drive of the brushless motor 1, an initial setting is performed (S1), a steering torque is detected (S2), and this detection signal is converted according to an algorithm. After processing, an output current corresponding to the detected steering torque is calculated (S3), and a time to be advanced is calculated based on the output current (S3).
4), start-up processing of the brushless motor 1 is performed (S5),
The processing from S2 is executed again. The advance time can be calculated by detecting the actual current flowing through the brushless motor 1 by the current detection circuit 15 and calculating based on the detected actual current.

In particular, in the calculation of the advance angle time in S4, assuming that the advance angle is α, the timing of the external interrupt processing to be described later is 60 degrees in electrical angle. By delaying the time and outputting a signal of a timer interrupt process described later, the advance angle = α degrees can be performed. The calculation of the time at that time is represented by the following equation with reference to FIG.

Tn = {Tn−2 × (60−α)} / 60 Further, by starting the brushless motor 1,
The external interrupt processing of (b) is executed, and this external interrupt processing is started by input of an interrupt signal (S
11) For the input interrupt signal, the count value of the interrupt signal input this time is subtracted from the count value of the interrupt signal input last time to calculate the cycle Tn of these interrupt signals (S12). , The drive output timer (timer interrupt period tn) is started (S1).
3) Execute the main routine again.

Next, the drive timer is turned off when the advance time calculated in S4 of the main routine has elapsed.
Then, a new timer interrupt process shown in FIG. 6C is started. In this timer interrupt process, a drive signal of the brushless motor 1 is output (S21), and the main routine is executed again.

A series of these processes will be described with reference to the timing chart of FIG. 7. By driving the brushless motor 1 by a start process, the U-phase and V-phase of the coil of the brushless motor 1 are passed through the rotor position detection circuit 14a. Phase, W
The detection signal from the low load sensor 8 (10) corresponding to the phase is taken into the control circuit 13a. Normally, commutation control can be performed by changing the state of the drive signal based on the detection signal.

When the drive output timer is turned off, the next commutation timing is determined. By subtracting the current interrupt signal from the previous interrupt signal shown in FIG. 7, the cycle tn of the drive signal is calculated, and the drive output timer is started. Then, when the drive output timer is turned off, the commutation control can be performed by advancing the angle by α degrees as compared with the normal time.

At this time, ON / O of FET1 to FET6
The timing waveform of the FF and the waveforms of energization and non-energization by the U-phase, V-phase, and W-phase positive / negative currents of the coil of the brushless motor 1 are the same as those in the first embodiment.

As a result, during normal operation, the low-load sensor 8
The commutation control is performed based on the detection signal from (10), and the brushless motor 1 can be rotated clockwise or counterclockwise at a timing corresponding to an optimum advance angle corresponding to a low load, while an external interrupt is generated. After the processing and the timer interrupt processing, commutation control is performed based on the cycle of the drive signal calculated from the interrupt signal, and the brushless motor 1 is rotated clockwise or counterclockwise at a timing corresponding to an optimum advance angle corresponding to a high load. Can be rotated.

Therefore, according to the second embodiment, only the CW low load sensor 8 (the CCW low load sensor 10) is provided, so that the low load and high load Accordingly, the brushless motor 1 can be driven at a timing corresponding to the optimum advance angle, so that the torque ripple during the rotation of the brushless motor 1 can be reduced, so that the steering feeling is improved, and it is particularly remarkable at a low load. And at the time of a high load, the output efficiency is improved and a large output can be obtained.

The present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the scope of the invention. For example, the advance angle is not limited to the two-stage setting corresponding to the low load and the high load, but may be set to three or more stages according to the load.

[0049]

According to the present invention, in an electric power steering apparatus using a brushless motor, the brushless motor is driven at a timing corresponding to an optimum advance angle corresponding to a load, so that the brushless motor is rotated. Torque can be reduced, the backlash of the steering wheel caused by the torque ripple can be eliminated, and the advance angle can be set to a position where the output efficiency under high load can be improved. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a main part of an electric power steering device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a sensor unit in the electric power steering device according to the first embodiment of the present invention.

FIG. 3 is a functional block diagram showing a control circuit of a brushless motor in the electric power steering device according to the first embodiment of the present invention.

FIG. 4 is a timing chart showing an operation of a control circuit unit of the brushless motor in the electric power steering device according to the first embodiment of the present invention.

FIG. 5 is a functional block diagram showing a control circuit of a brushless motor in the electric power steering device according to the second embodiment of the present invention.

FIGS. 6 (a), (b) and (c) are flowcharts showing processing of a control circuit of a brushless motor in an electric power steering apparatus according to Embodiment 2 of the present invention.

FIG. 7 is a timing chart showing an operation of a control circuit of a brushless motor in the electric power steering device according to the second embodiment of the present invention.

FIG. 8 is based on the assumption that torque ripple (sensor position: advance angle 0) under a low load simulated by the inventor of the present invention.
FIG.

FIG. 9 is based on the assumption that torque ripple (sensor position: advance angle 7) under a low load simulated by the inventor of the present invention.
FIG.

FIG. 10 is a characteristic diagram showing a relationship between a lead angle and a torque ripple simulated by the inventor on the premise of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brushless motor 2 Rack axis 3 Steering handle 4, 4a Control circuit part 5 Ball screw drive part 6 Torque sensor 7 Sensor part 8 CW low load sensor 9 CW high load sensor 10 CCW low load sensor 11 CCW high load Sensor 12 FET gate circuit 13, 13a Control circuit 14 Rotor position signal selection circuit 14a Rotor position detection circuit 15 Current detection circuit

Claims (2)

[Claims] 1. A brushless motor for generating a steering assist force, a driving unit for energizing / de-energizing coils of each phase of the brushless motor to rotate the brushless motor in a predetermined direction, and a load applied to the brushless motor Load detecting means for detecting the position of the rotor of the brushless motor at timings corresponding to different advance angles, and the load detecting means of the plurality of position detecting means Selects a detection signal of one position detection means of the brushless motor in accordance with the load detected by the control means, controls the driving means based on the detection signal of the selected position detection means, and controls each phase of the brushless motor. And control means for controlling the energization / de-energization time of the coil at a timing corresponding to a predetermined advance angle. An electric power steering apparatus, wherein the brushless motor is driven at a timing corresponding to an advance angle corresponding to a load. 2. A brushless motor for generating a steering assist force, driving means for energizing / de-energizing coils of each phase of the brushless motor to rotate the brushless motor in a predetermined direction, and a load applied to the brushless motor Load detecting means for detecting the position of the rotor of the brushless motor at a predetermined timing, based on a detection signal of the position detecting means of the brushless motor according to the load detected by the load detecting means. Generates a timing signal corresponding to a predetermined advance angle, and controls the drive means by this timing signal, and controls the energization / non-energization time of the coil of each phase of the brushless motor at a timing corresponding to the predetermined advance angle. Control means for controlling the brushless motor at a timing corresponding to an advance angle corresponding to a load applied to the brushless motor. An electric power steering device characterized by driving a less motor.