JP2000134969A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low price motor control device which can control the operation from a low speed operation to a high speed operation by reducing the number of slits of a disc for determining rotor position used in the SR motor controller. SOLUTION: An SR motor comprises a rotor 11 having four projections 13 and a stator 12 including six coils 14u to 14w and rotates when an exciting voltage is sequentially applied to each coil 14u to 14w. Such SR motor controller includes a disc 31 and position signal detecting sensors 32u to 32w. The disc 3 is provided with four slits 33 which are allocated in relation to each projection explained above. Each sensor 32u to 32w is provided at three positions in relation to each coil 14u to 14w. The excitation voltage is controlled on the basis of the actual number of rotations of rotor 11. Namely, application of exciting voltage is started and stopped after lapse of time of the first and second predetermined times based on the actual number of rotations from detection of the position signal by each sensor 32u to 32w.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SR (switched type) used for an electric pump type power steering device and the like.
More particularly, the present invention relates to a technique for optimally driving a motor by voltage control according to a rotor position of the motor.

[0002]

2. Description of the Related Art In recent years, adoption of an SR motor or the like as a power means for driving an oil pump of a power steering apparatus for a vehicle has been studied. Such a motor control device is configured by combining a disk having a number of precise slits provided in a circumferential direction and one encoder for detecting a position signal from the slit in order to detect a rotor position. You. Then, the motor is controlled based on the detected rotor position.

[0003]

However, such a conventional motor control device has the advantage that the position of the rotor can be detected with high accuracy by the encoder. Since it is necessary to provide each time, processing is complicated, and there is a disadvantage in terms of cost.

In view of such circumstances, the present invention employs an SR motor as a pump driving motor, and eliminates the above-mentioned cost disadvantages by drastically reducing the number of slits provided in a disk. It is an object of the present invention to provide an inexpensive motor control device capable of controlling from a low speed to a high speed.

[0005]

For this reason, in the invention according to claim 1, as the above-mentioned SR motor, a rotor having four projections containing magnetic material arranged at equal intervals in the circumferential direction, And a stator having six coils arranged at equal intervals.

[0006] The rotation of the rotor is induced by sequentially applying the same phase excitation voltage to each of the coils arranged at the axially symmetric position.
Such an SR motor control device includes a disk and three position signal detection sensors.

The disk is arranged so as to rotate in synchronization with the rotor, and is provided with four slits arranged at predetermined positions in consideration of the position of each projection. on the other hand,
The position signal detection sensor indicates the position of each slit,
The coils are arranged so as to be detected at predetermined positions corresponding to the coils to which the excitation voltages of the respective phases are applied.

Further, as shown in FIG. 1, after a lapse of a first predetermined time from the detection of the position signal by each of the sensors, an excitation voltage of a corresponding phase is applied to a corresponding coil. Voltage control means for stopping the application of the excitation voltage after a second predetermined time which is longer than the first predetermined time, and actual rotation speed measurement means for measuring an actual rotation speed of the rotor; Application timing setting means for variably setting the first predetermined time in accordance with the actual rotation speed; and stop timing setting means for variably setting the second predetermined time in accordance with the actual rotation speed.

The invention according to claim 2 is characterized in that the application timing setting means sets the first predetermined time short when the actual rotation speed is high. In other words, there is a certain time difference between the start of the application of the excitation voltage to the coil and the generation of the effective electromagnetic force. Therefore, taking this into consideration, the timing of starting the application of the excitation voltage during high-speed rotation ( Application timing).

According to a third aspect of the present invention, the stop timing setting means extends the application time corresponding to the difference between the second predetermined time and the first predetermined time when the actual rotation speed is high. The second predetermined time is set to be short.

That is, in consideration of the necessity of supplying a larger amount of energy during high-speed rotation than during low-speed rotation, the time for applying the excitation voltage is extended, and the application of the excitation voltage is stopped. The stop timing (stop timing) is also advanced in consideration of the time difference from when the electromagnetic force disappears until the electromagnetic force disappears.

The invention according to claim 4 is characterized in that the voltage control means is executed with reference to a fall at the end of the position signal. That is, the application timing is set after the first predetermined time from the detection of the fall, and similarly, the stop timing is set after the second predetermined time from the detection of the fall.

The invention according to claim 5 is characterized in that the voltage control means is executed with reference to a rise at the head of the position signal. The invention according to claim 6 is
The width of each slit is set so that another position signal detection sensor detects the rise of the position signal before one position signal detection sensor detects the fall of the position signal.

That is, the width of each slit is set to be wider so that at least one of the three position signal detection sensors always detects a position signal.

[0015]

According to the first aspect of the present invention, the number of slits provided in the disk is reduced to four, thereby simplifying the processing and eliminating the conventional cost disadvantage.

Further, since each of the slits is arranged in relation to each projection of the rotor and each position signal detecting sensor is arranged in relation to the position of each coil, each slit is detected from each position signal detected. The positional relationship between the protrusion and each coil can be grasped, and the application and stop timing of the excitation voltage of each phase can be easily determined.

Further, by setting the application and stop timings according to the actual number of revolutions, highly reliable control according to the driving state can be performed. According to the second aspect of the present invention, by setting the application timing earlier during high-speed rotation, the generation timing of the electromagnetic force can be optimized, and the operating range of the SR motor can be expanded.

According to the third aspect of the present invention, the required energy can be supplied without increasing the excitation voltage by setting the stop timing earlier during high-speed rotation so as to extend the application time. In addition, since the timing for extinguishing the electromagnetic force can be optimized and unnecessary voltage supply can be eliminated, power consumption can be reduced.

According to the fourth and fifth aspects of the present invention, by setting the application and stop timings based on the fall or rise of the position signal, each timing can be easily determined.

According to the sixth aspect of the present invention, it is possible to avoid a state in which none of the sensors detects a position signal, and the processing accuracy is reduced, so that the cost can be further reduced.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a system schematic diagram of a control device for an SR motor according to an embodiment of the present invention. The SR motor is a three-phase type and is used as power means for driving an oil pump of an automobile power steering device. .

FIG. 3 is a schematic diagram showing the internal structure of the present SR motor. FIG. 4 is a schematic view showing the internal structure of the control device main body of the SR motor, wherein the right side of the figure shows a front view and the left side shows a side view.

The basic configuration of the present SR motor and its control device will be described with reference to FIGS. Reference numeral 1 shown in FIG.
To pressurize a cylinder (not shown) to generate a steering assist force.

The SR motor 1 includes a rotor 11 and a stator 12, as shown in FIG.
The rotor 11 has four protrusions 13 arranged at equal intervals on the outer periphery thereof. On the other hand, the stator 12 has six coils 14u, 14v arranged at equal intervals on the inner circumference thereof.
And 14w.

The above-mentioned coils are arranged at axially symmetric positions with the same reference numerals. The present SR motor performs a rotation operation by sequentially applying an excitation voltage called a U-phase voltage, a V-phase voltage, and a W-phase voltage to each of the coils 14u to 14w. In the following, each of the coils 1
4u to 14w correspond to the phase of the excitation voltage to be applied.
Phase coil 14u, V-phase coil 14v, W-phase coil 14w
Called.

The control device for an SR motor configured as described above includes a control device main body 3 and a control unit 4 connected thereto. As shown in FIG. 4, the control device main body 3 includes a disk 31 and three position signal detection sensors 32 (only one is shown in a side view for convenience) inside.

The shaft of the disk 31 is connected to the rotor 11 and rotates in synchronization with the rotor. Also,
Four slits 33 are provided, and each slit 33
Is set to have a width such that the central angle is 30 degrees,
As described later, they are arranged at predetermined positions corresponding to the projections 13.

As will be described later, each of the sensors 32 is disposed at an interval of 120 ° at three positions corresponding to the coils of each phase, and generally includes a light projecting unit 32a and a light receiving unit 3a.
2b.

The control unit 4 executes control for starting application of the excitation voltage of each phase to the corresponding coil based on the position signal detected by each sensor 32, and further stopping the application.

Next, the basic operation of the present SR motor will be described with reference to FIG. 5 together with the position signal detected at that time.
2A and 2B show, for convenience, the rotor 11, the stator 12, and the disk 3 which are the components of the SR motor.
1 and the position signal detection sensor 32 are displayed in an overlapping manner.

(A) shows the positional relationship between the components at time ta, and (b) shows the same positional relationship at time tb. FIG. 4C shows the output signals of the sensors 32 during this time period.

In the present embodiment, each slit 33 is formed
As shown in (a) and (b), each is shifted in the advance direction by 15 degrees with respect to the projection 13. Also,
Each sensor 32 is connected to each coil 14 as indicated by the points in the figure.
It is arranged on a straight line connecting u to 14w so as to pass over the center of the slit.

In the following, among the sensors 32,
The U-phase sensor 32u is located on the straight line connecting the U-phase coil 14u, the V-phase sensor 32v is located on the straight line connecting the V-phase coil 14v, and the V-phase sensor 32v is located on the straight line connecting the W-phase coil 14w. Is referred to as a W-phase sensor 32w.

Referring to FIG. 5A, the U-phase coil 14
The protrusion 13 is located at a position opposing the position u, and as shown in FIG. 3C, the U-phase sensor 32u detects the trailing edge of the position signal and the V-phase sensor 3u.
2v detects the leading edge of the position signal.

In this state, if an exciting voltage is applied only to the V-phase coil 14v, a rotational force is generated in the direction indicated by the arrow in the figure. Thereafter, until time tb, V-phase sensor 3
Only 2v detects the position signal.

When the rotor 11 rotates 30 degrees from the state shown in FIG. 4A and reaches the time tb, the state shown in FIG. 4B is reached, and the projection 13 faces the V-phase coil 14v. The V-phase sensor 32v detects a fall, and the W-phase sensor 32w detects a rise.

In this state, if the application of the excitation voltage to the V-phase coil 14v is stopped and only the W-phase coil 14w is applied, the rotor rotates in the same manner as described above, and further rotates by 30 degrees from the state of (b). As a result, the projection 13 faces the W-phase coil 14w, and the W-phase sensor 32w detects the fall and the U-phase sensor 32u detects the rise (t
c).

Here, by repeating the same procedure as described above,
The rotor 11 further rotates by 30 degrees and returns to the same state as (a). As described above, the time required for the rotor 11 to rotate 90 degrees is considered as one cycle.

During one period, each of the sensors 32u to 32w detects a position signal one by one in order. Therefore, based on these position signals, the excitation voltage can be sequentially applied to each of the coils 14u to 14w.

Next, the voltage control executed according to the present embodiment will be described with reference to FIGS. This control routine controls the next voltage supply based on the detected position signal. Therefore, it is noted that the excitation voltage supplied this time is controlled based on the position signal detected last time.

Also, from the above description, it is assumed that the rotor 11 is 30
It is clear that the same voltage control is sequentially performed on the coils 14u to 14w of each phase every time the motor rotates by one degree, so here, only the voltage control on the V-phase coil 14v will be considered.

When the SR motor 1 rotates at a relatively low speed, the excitation voltage is controlled as shown by a waveform (a) in FIG. In S1 shown in FIG. 6, an output signal from the V-phase sensor 32v is read. When confirming the position of the slit 33, the V-phase sensor 32v detects a position signal (ta).

Here, the application of the V-phase voltage is started based on the position signal detected last time (at the same time, the application of the U-phase voltage is stopped based on the position signal detected last time by the U-phase sensor 32u). ).

In S2, it is determined whether or not the fall of the position signal has been detected. When the falling is not detected, the process is returned, the output signal of the V-phase sensor 32v is read again, and the same determination is repeated.

On the other hand, if it is detected (tb), the process proceeds to S3, and the timer starts counting the elapsed time T. At the same time as the detection of the fall, the W-phase sensor 32w detects the rise, and the application of the V-phase voltage is stopped and the application of the W-phase voltage is started in the same manner as described above. Therefore, the rotor 11 further rotates to reach the time tc, and the same control is executed.

At S4, the actual number of revolutions of the rotor 11 is measured. The actual number of revolutions can be calculated, for example, from the elapsed time from the previous fall, which is the position signal detection cycle, to the current fall. The cycle is such that the rotor 11 is 90
This is because it is equal to the time required for rotating by degrees.

This part corresponds to the actual rotation speed measuring means.
In S5, the next application timing is set based on the actual rotational speed measured in S4. In the present embodiment, this is set as the elapsed time t1 from the currently detected fall, as shown in FIG.

This part corresponds to the application timing setting means. In S6, the next stop timing is set based on the actual rotation speed. This is set longer than the elapsed time t1, and similarly set as the elapsed time t2 from the fall.

This part corresponds to the stop timing setting means. In S7, if the application of the excitation voltage is not stopped at time tb, this is forcibly stopped. While the detection of the position signal depends on the rotation of the disk 31, the stop timing is controlled by time, so that the excitation voltage is continuously applied even after the fall is detected (a reverse driving force is generated). In order to avoid this, such processing is provided.

At S8, the control shown in FIG. 7 is started. In FIG. 7, in S10, it is determined whether or not the elapsed time T has reached t1. If not reached, the same determination is repeated until this is reached, while if reached (td)
Starts the application of the V-phase voltage in S11.

In S12, it is determined whether or not the elapsed time T has reached t2. If not reached, the same determination is repeated until this is reached, while if reached (te)
Stops the application of the V-phase voltage in S13.

Steps S10 to S13 correspond to voltage control means. On the other hand, when the SR motor 1 rotates at a high speed, the excitation voltage is controlled as shown by the waveform (b) in FIG.

This can be executed by the same process as the control shown in FIGS. 6 and 7, but the elapsed time from the falling edge to the application timing and the stop timing is calculated as follows.
The difference is that they are set as shown by t1 'and t2' in FIG.

In setting the elapsed times t1 'and t2', a time difference between the start and stop of the application of the excitation voltage and the generation and disappearance of an effective electromagnetic force is taken into consideration. In addition, at the time of high-speed rotation, it is necessary to increase the amount of energy supply as compared with at the time of low-speed rotation, so that the application time is set to be extended (t2'-t1 ').

Although the above control is executed with reference to the fall of the position signal, it is apparent that the same effect can be obtained with reference to the rise of the position signal. In another embodiment of the present invention, the width of each slit 33 is adjusted such that another position signal detection sensor detects the rise of the position signal before one position signal detection sensor detects the fall of the position signal. Set.

This can be achieved, for example, by setting the width of each slit 33 so that the central angle is wider than 30 °, as shown in FIG. FIG. 10 shows the signal waveforms output by the position signal detection sensors 32u to 32w in this case, and as shown, the sensor output signals of each phase overlap.

In still another embodiment of the present invention, the control device main body 3 is disposed on the opposite side of the SR motor 1 with respect to the oil pump 2 as shown in FIG. By doing so, the heat generated by the SR motor 1 is prevented from being transmitted to the position signal detection sensors 32u to 32w, and each sensor can be made of a material having low heat resistance, so that the cost can be further reduced. Can be.

As described above, according to the present invention, the number of slits provided on the disk for determining the rotational position of the rotor can be reduced to four, so that the processing can be simplified and the disadvantage in cost can be eliminated.

Further, since the application and stop timings can be variably set based on the actual number of revolutions of the rotor, highly reliable control according to the driving state can be performed, and power consumption can be reduced.

In the above description, an example is shown in which the present invention is applied as a power means for rotating an oil pump of a power steering device for an automobile. However, various applications as a device for controlling an SR motor used for other purposes. It is clear that there is.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of the present invention.

FIG. 2 is a system schematic diagram of an SR motor control device according to an embodiment of the present invention.

FIG. 3 is a schematic diagram showing an internal structure of the SR motor according to the first embodiment;

FIG. 4 is a schematic diagram showing an internal structure of a control device main body of the SR motor.

FIG. 5 is a diagram showing a basic operation of the SR motor and a control device therefor;

FIG. 6 is a flowchart showing a processing routine of a sensor output signal.

FIG. 7 is a flowchart showing voltage control.

FIG. 8 is a diagram showing a voltage waveform controlled by a control device for an SR motor according to an embodiment of the present invention.

FIG. 9 is a diagram showing a disk of a control device for an SR motor according to another embodiment of the present invention.

FIG. 10 is a diagram showing a sensor output signal when the control device is used.

FIG. 11 is a system schematic diagram of a control device for an SR motor according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 SR motor main body 2 Oil pump 3 Control device main body 4 Control unit 11 Rotor 12 Stator 13 Projection 14 Coil 31 Disk 32 Position signal detection sensor 33 Slit

Claims (6)

[Claims] A rotor having four protrusions each including a magnetic material arranged at equal intervals in a circumferential direction; and a stator having six coils arranged at equal intervals in a circumferential direction. In a control device for a motor driven by sequentially applying an excitation voltage of the same phase to one of the coils arranged at an axially symmetric position, the motor rotates in synchronization with the rotor and is arranged at a predetermined position corresponding to each projection. A disc having four slits, and three position signal detection sensors for detecting the position of each slit at a predetermined position corresponding to a coil for applying the excitation voltage of each phase, After the sensor detects the position signal, an excitation voltage is applied to a corresponding coil after a first predetermined time has elapsed, and the excitation voltage is applied after a second predetermined time longer than the first predetermined time has elapsed. Voltage control means for stopping application; actual rotation number measuring means for measuring the actual rotation number of the rotor; application timing setting means for variably setting the first predetermined time according to the measured actual rotation number. And a stop timing setting means for variably setting the second predetermined time in accordance with the actual rotation speed. 2. The motor control device according to claim 1, wherein said application timing setting means sets said first predetermined time short when said actual rotation speed is high. 3. The method according to claim 1, wherein the stop timing setting means extends the application time corresponding to a difference between the second predetermined time and the first predetermined time when the actual rotation speed is high. 3. The motor control device according to claim 2, wherein the time is set short. 4. The motor control device according to claim 3, wherein said voltage control means uses a fall at the end of said position signal as a reference. 5. The motor control device according to claim 3, wherein said voltage control means uses a rise at the head of said position signal as a reference. 6. The width of each slit is set so that another position signal detection sensor detects the rise of the position signal before one position signal detection sensor detects the fall of the position signal. The motor control device according to claim 4 or 5, wherein