JP2002262541A - Method for detection of position of three-phase reluctance motor and method for control of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a starting torque characteristic in a method for controlling detection of a position of a rotor utilizing a three-phase reluctance-motor position detecting means. SOLUTION: Three position-detection Hall elements Hu1, Hv1, and Hw1 of the three-phase reluctance motor are allocated to provide the interval of 60 deg. or 120 deg. from a desired reference position, a position-detection Hall element Hu2 is allocated to provide a phase difference of 30 deg.×(2n-1) (n is natural number) in terms of an electrical angle for the position-detection Hall element Hu1, position-detection Hall elements Hv2, Hw2 are allocated to provide the interval of 60 deg. or 120 deg. in terms of the electrical angle for a position-detection Hall element Hu2, and a power feeding control is conducted in the electrical angle of 150 deg. based on a position detection signal obtained from the position- detection Hall elements Hu1, Hv1 and Hw1 and Hu2, Hv2 and Hw2 in order to improve the starting torque characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase reluctance motor having a rotor position detecting means for detecting the position of a rotor using the position detecting means and energizing based on a position detection signal. Method and control method.

[0002]

2. Description of the Related Art Conventionally, a simple control method of a three-phase brushless DC motor will be described with reference to FIGS. In FIG. 4, a position detecting magnet is arranged on a rotor or a shaft that rotates in synchronization with the rotor. Position detecting Hall elements Hu3, Hv3, and Hw3 are disposed at positions opposed to the position detecting magnet Mg at a predetermined electrical angle from an arbitrary reference position.

For example, in FIG. 4, three position detecting Hall elements Hu3, Hv3 and Hw3 are arranged at an interval of 120 ° from an arbitrary reference position.

FIG. 5 shows six switching elements U +, three-phase bridges according to the pattern of position detection signals obtained by the three position detection Hall elements Hu3, Hv3, Hw3 of FIG. U-, V +, V-, W +, W
1 shows a basic circuit configuration of a power conversion unit that controls a motor by appropriately energizing “−”.

In FIG. 6, three Hall elements Hu3, Hv3 and Hw3 for position detection are arranged at an electrical angle of 120 °, and 1
FIG. 4 shows a time chart when 20 ° is energized. In the upper part of FIG. 6, the position detecting Hall elements Hu3, Hv
3, the position detection signal of Hw3. In the lower part, the position detecting Hall elements Hu3, Hv shown in the upper part are shown.
3, each switching element U +, U−, V +, of the power converter obtained based on the position detection signal detected from Hw3
Output signals to V−, W +, W− are shown. The motor is driven by the switching elements U +, U-, V +, V-, W +, W- of the power conversion unit shown in FIG. 5 according to the pattern of the position detection signals sent from the position detection Hall elements Hu3, Hv3, Hw3. I have.

For example, in the section (A), the switching elements U + and V- are energized, and two phases are energized from the U-phase to the V-phase among the three-phase windings wound on the stator of the motor. In the case of the section (B), the switching element U
+ And W- are energized, so that two phases are energized from the U phase to the W phase of the three-phase winding. Similarly, in the section (C) and thereafter, power is supplied to two of the three-phase windings. As described above, the motor is controlled and operated by repeating the two-phase energization with the electric angle of 60 ° as the energization width of one pattern.

That is, an electrical angle of 6 is obtained by a combination of three position detections.
Detects six patterns of position detection signals per one cycle of every 0 ° and appropriately energizes the switching elements U +, U−, V +, V−, W−, W +, W− of the power conversion unit in FIG. 5 based on the position detection signals. Control operation of the motor. This control method uses the switching elements U +, U-, V +, V-, W
Since the width of the + and W- currents is 120 ° in electrical angle, it is usually called 120 ° current (hereinafter referred to as 120 ° current).

[0008]

It is possible to operate a three-phase reluctance motor using the aforementioned 120 ° energization. However, for a three-phase brushless DC motor that has a permanent magnet in the rotor and generates magnet torque,
A three-phase reluctance motor that operates only with reluctance torque without having a permanent magnet in the rotor is different in the generated torque and energization region.

Referring to FIG. 7, the torque generated by both motors will be described. FIG. 7A shows a surface-attached three-phase brushless DC in which a permanent magnet is attached to the surface of a rotor.
It is a torque characteristic of a motor. The reluctance torque in this case does not need to be considered because it is extremely small as compared with the ratio of the magnet torque. (B) shows the torque characteristics of the three-phase reluctance motor, in which only the reluctance torque is generated. In FIGS. 7A and 7B, the horizontal axis represents an electrical angle for indicating a current phase, and the vertical axis represents generated torque.

FIG. 8 is a graph showing the relationship between the magnet torque of the three-phase brushless DC motor described with reference to FIG. 7 and the reluctance torque of the three-phase reluctance motor. It shows a conceptual diagram for comparison.

FIG. 8A shows the generated torque of the three-phase brushless DC motor, and FIG. 8B shows the generated torque of the three-phase reluctance motor. FIG. 8C compares the generated torques of both motors at the same time.

As shown in FIG. 8, the three-phase reluctance motor has a three-phase brushless DC when the width of the torque generated when the two-phase current is supplied.
There is only 90 electrical angle to 180 electrical angle of the motor.

In the conventional 120 ° energization, two-phase energization is performed so as to be in a region where the torque is the largest in an energization section with an electrical angle of 60 ° which is the minimum unit of the energization pattern.
In (a) and (b) of FIG. 8, the conduction width at an electrical angle of 60 ° is indicated by hatched portions. When comparing the torque generated at both ends of the conduction width of 60 ° in the conduction section, the both ends of the conduction width of 60 ° in the conduction section of the three-phase brushless DC motor are represented by T.
When expressed as Tmin2, the two ends of the conduction width of the conduction section 60 ° of the three-phase reluctance motor are represented as Tmin2.
In the three-phase reluctance motor Tmin2, the torque generated at both ends of the energized section 60 ° is considerably lower than Tmin1 of the phase brushless DC motor.

Assuming that the generated torque of both motors is a sine wave and the maximum value of the generated torque is 1, Tmin1 is about 0.87
And Tmin2 is about 0.50 times, 3 times when two-phase current is applied.
The minimum value of the generated torque of the phase reluctance motor is considerably lower than that of the three-phase brushless DC motor.

Therefore, in a device requiring a large starting torque in a three-phase reluctance motor, FIG.
When the 120 ° energization shown in (1) is performed, the torque may be insufficient near the switching of the two-phase energization pattern, that is, at both ends of the energization width, and the start may not be performed. To solve such a problem, a larger torque is required. In order to obtain such a large torque, the size of the motor must be increased,
It is necessary to take measures such as increasing the power capacity of the switching element and the like of the power conversion unit, which is a very large cost increase factor.

[0016]

According to the present invention, a rotor of a three-phase reluctance motor or a position detecting magnet provided on a shaft rotating in synchronization with the rotor is disposed at a position opposed to a position detecting magnet by a rotation angle of the rotor. Are arranged at an electrical angle of 60 ° or 120 ° from the reference position, and three Hall elements Hu1, Hv1 and Hw1 are arranged at an electrical angle of 30 ° with respect to the Hall element Hu1. The position detecting Hall element Hu2 is disposed so as to have a phase difference of ° × (2n−1) (n is a natural number), and the position detecting Hall elements Hv2 and Hw2 are electrically angled with respect to the position detecting Hall element Hu2. In this method, the position of the three-phase reluctance motor arranged so as to be spaced at an angle of 60 ° or 120 ° is used to eliminate the torque valley at both ends of the conduction width. It is possible to increase the position detection accuracy and to manufacture it at low cost.

In addition, a control method in which the energization width of the switching element of the power conversion unit is energized by 150 ° in electrical angle based on the signals detected by the six position detection Hall elements is used. The torque valleys at both ends of the current-carrying width are eliminated, and even in a device that requires a large starting torque as described above, the lack of torque can be compensated and good starting characteristics can be obtained, and the device can be manufactured at low cost.

[0018]

FIG. 1 shows an embodiment of the present invention. In FIG. 1, a position detecting magnet Mg magnetized to four poles is arranged so that the rotor adjacent to the rotor rotating in synchronization with the rotor or the rotor of the three-phase four-pole reluctance motor becomes a different pole. I have. In the present embodiment, three position detecting Hall elements Hu1, Hv1, Hw1 are arranged at positions opposed to the position detecting magnet Mg so as to be separated from the arbitrary reference position by an electric angle of 120 ° with respect to the rotor rotational electric angle. Has been arranged. In this case, the electrical angle of the rotor rotation may be set to be 60 ° from an arbitrary reference position.

For example, when the electrical elements are arranged at intervals of 60 °, the Hall elements for position detection Hu1, Hw1, Hv1 are arranged in this order, and the Hall element for position detection located at the center is Hw.
If it is set to 1, Hall elements Hu1 and Hv for position detection at both ends are provided.
1 is an electrical angle of 120 °, and the position detection signal of the position detecting Hall element Hw1 located at the center is 180 °.
By inverting, it can be virtually the same as arranging the position detection Hall elements Hu1, Hv1, and Hw1 at an electrical angle of 120 °.

Further, a position detecting Hall element Hu2 is arranged on the same circumference so as to have a phase difference of, for example, 90 ° in electrical angle with respect to the position detecting Hall element Hu1. Hall element Hv for position detection
2 and Hw2 are arranged at an interval of 120 electrical degrees.

In this embodiment, the case where the position detecting Hall elements Hu1, Hv1, Hw1 are arranged at an electrical angle of 120 ° and the phase difference between the position detecting Hall elements Hu1 and Hu2 is set to an electrical angle of 90 ° is shown. However, the same effect can be obtained even when the phase difference is 30 °, 150 °, 210 °, 270 °, 330 °, etc., and the electrical angle is 30 ° × (2n−1) (n is a natural number). it can.

In this embodiment, the phase difference between the position detecting Hall elements Hu1 and Hu2 has been described. However, the phase difference between the position detecting Hall elements Hv1 and Hv2 is 3 electrical degrees.
0 ° × (2n−1) (n is a natural number), and the position detecting Hall elements Hu2 and H2 are different from the position detecting Hall element Hv2.
w2 may be an electrical angle of 60 ° or 120 °. The phase difference between the position detecting Hall elements Hw1 and Hw2 is an electrical angle of 30 ° × (2n−1) (n is a natural number), and the position detecting Hall elements Hu2 and Hv2 are electrically connected to the position detecting Hall element Hw2. 60 ° or 120 in angle
° intervals may be used. Therefore, the phase difference between the reference position detection Hall element and the reference position detection Hall element is 30 ° in all cases.
X (2n-1) (n is a natural number) may be satisfied, and the gist of the present invention can be achieved.

FIG. 2 is a time chart in the case where a current of 150 ° is applied using the configuration of the embodiment of FIG. In the upper part of FIG. 2, the position detection Hall elements Hu1, Hv1, Hw are shown.
1 and the position detection signals of Hu2, Hv2, and Hw2. In the lower part, the respective Hall elements Hu1, Hv1, Hw1 and Hu2, Hv2, Hw1 for position detection shown in the upper part are shown.
2, the switching elements U +, U−, V +, V−, W of the power converter obtained based on the position detection signal detected from
+, W- represents an output signal.

In FIG. 2, the position detecting Hall element Hu1,
Hv1 and Hw1 are arranged at a phase difference of 120 ° in electrical angle, and Hv1 and Hw1 are set to H with respect to the position detection Hall element Hu1.
The phase difference from u2 is 90 ° in electrical angle, and the position detecting Hall element Hv is different from the position detecting Hall element Hu2.
2 and Hw2 are out of phase by 120 ° in electrical angle.

In the embodiment shown in FIG. 1, for example, in the section (a) of FIG. 2, the switching elements U +, W + and V-
Are energized, and the motor windings U-phase and W-phase
Power is supplied to the three phases. Next, in the section (b), the switching elements U + and V- are energized, and energize in two phases from the motor winding U phase to the V phase. Further, in the section (c), the switching elements U +, V- and W- are energized, and energize three phases from the motor winding U phase to the V and W phases. In this way, from three-phase current to two-phase current,
Further, the motor is operated by alternately energizing two phases and three phases in which the electric angle of 30 ° is one pattern of the energizing width to three-phase energization.

That is, an electrical angle of 3 is obtained by a combination of six position detections.
FIG. 5 shows a conventional example based on the detected position detection signals based on the detected position detection signals of 12 patterns per one cycle of every 0 °.
Switching elements U +, U-, V +, V
The motor can be operated by appropriately energizing-, W + and W-. In this case, each switching element U
+, U-, V +, V-, W +, and W- are 150 ° in electrical angle. (Hereafter, this energization method is referred to as 150 ° energization.)

Therefore, in a device that requires a large starting torque with a three-phase reluctance motor, three position detecting Hall elements Hu1 that are spaced 60 ° or 120 ° from an arbitrary reference position in electrical angle. , Hv1,
Hw1 is arranged, and the Hall element for position detection Hu2 is electrically connected to the Hall element for position detection Hu1 by an electrical angle of 30 ° ×
(2n-1) (n is a natural number), and the position detection Hall elements Hv2 and Hw2 are arranged at an electrical angle of 60 ° or 12 with respect to the position detection Hall element Hu2.
By arranging them at 0 ° intervals, it is possible to solve problems such as poor starting due to insufficient torque near pattern switching in two-phase conduction, that is, at both ends of the conduction width. As a result, it is not necessary to take measures such as increasing the size of the motor in order to obtain a large torque or increasing the power capacity of the switching element and the like of the power conversion unit, and the cost is not significantly increased.

FIG. 3 is a conceptual diagram of a torque waveform according to each energizing method. FIG. 3A shows the generated torque when the two-phase energization is repeated, and FIG. 3B shows the generated torque when the three-phase energization is repeated. FIG.
In (c), two-phase energization and three-phase energization are alternately repeated.
The generated torque at the time of 50 ° conduction is shown. Comparing the torque characteristics of (a) and (b), the peak of the three-phase energization torque is at a position corresponding to the torque valley during the two-phase energization.

That is, the width of the torque generated during the two-phase energization of the three-phase reluctance motor shown in FIG. The abrupt torque change occurring at both ends of ° degrades the starting torque characteristics of the motor. Also,
The width of the torque generated at the time of the three-phase energization shown in FIG.
At 0 °, the energization width is the region where the torque is the largest, and the sudden change in torque occurring at both ends of the energization section 60 ° as described above deteriorates the starting torque characteristics of the motor.

However, as shown in FIG.
As the energization, two-phase energization and three-phase energization are alternately and repeatedly energized, so that the position at which the torque generated during three-phase energization is maximized is matched with the position at the valley of the torque generated during two-phase energization. Thereby, a stable maximum torque can be obtained. That is, an energizing section 60 generated during two-phase energization and three-phase energization of the three-phase reluctance motor.
The two-phase energization and the three-phase energization are alternately repeated to control the steep valley of the torque generated at both ends of the angle so that the width of one energization becomes 30 °. can do.

Therefore, it is possible to solve problems such as poor starting due to insufficient torque near the switching of the three-phase reluctance motor during the two-phase energization. As a result, a large torque can be obtained, and it is not necessary to take measures such as enlarging the size of the motor or increasing the power capacity of the switching elements of the power conversion unit. It is possible to do. In addition, since there is no sharp valley of torque generated at both end portions of the energized section at 60 °, a stable torque characteristic is obtained, and noise caused by control is obtained.
Vibration and the like can be reduced.

The above description is based on the position Hall elements Hu1, Hv
1, Hw1 are arranged at intervals of 120 electrical degrees, the phase difference between the position detecting Hall elements Hu1 and Hu2 is set to an electrical angle of 90 °, and Hv2 and Hv are set with respect to the position detecting Hall elements Hu2.
Although the case where w2 is 120 ° in electrical angle has been described, the position Hall elements Hu1, Hv1 and Hw1 are arranged at intervals of 60 ° or 120 ° in electrical angle, and the phase difference between the position Hall elements Hu1 and Hu2 is 30 electrical degrees. ° × (2n−1) (n is a natural number), and the position detection Hall element Hu2 is Hv
By setting the electrical angle of 2 and Hw2 to 60 ° or 120 °, 12 patterns of position detection signals can be obtained for each electrical angle of 30 °, so that the present invention can be implemented. The phase difference between the position detecting Hall elements Hu1 and Hu2 is determined by the position detecting Hall elements Hv1 and Hv1.
v2, the phase difference between Hw1 and Hw2 may be 3
If 0 ° × (2n−1) (n is a natural number), the same effect can be obtained.

[0033]

The present invention provides a three-phase reluctance motor having a rotation angle of a rotor at an electrical angle from an arbitrary reference position at a position opposed to a position detecting magnet mounted on a rotor or a shaft rotating in synchronization with the rotor. At 60 ° or 12
Three position detecting Hall elements Hu1, Hv1, Hw1 arranged at 0 ° intervals, and an electrical angle of 30 ° × (2n−1) with respect to the position detecting Hall elements Hu1.
(N is a natural number) with respect to the position detection Hall element Hu2 and the position detection Hall element Hv2, Hw so as to have a phase difference of
2 are arranged so as to have an electrical angle of 60 ° or 120 °, and the position detecting Hall elements Hu1, Hv1, H
By controlling the energization of the electrical angle of 150 ° based on the position detection signals obtained from w1, Hu2, Hv2, and Hw2, it is possible to raise the position at the valley of the torque as compared with the energization at 120 °. Characteristics can be obtained. Further, since the torque change width is reduced, vibration and noise during operation of the three-phase reluctance motor can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a position detecting magnet according to an embodiment of the present invention.

FIG. 2 is a time chart at the time of 150 ° conduction.

FIG. 3 is a conceptual diagram of a torque waveform according to each energization method.

FIG. 4 is a cross-sectional view of a position detecting magnet showing a conventional example.

FIG. 5 is a schematic diagram of a power converter.

FIG. 6 is a time chart at the time of 120 ° conduction.

FIG. 7 is a conceptual diagram of torque generated in a three-phase brushless DC motor and a three-phase reluctance motor.

FIG. 8 is a conceptual diagram in which torques generated around a torque peak are simply compared at the same time in order to simultaneously compare the motor torques shown in FIG. 7;

[Explanation of symbols]

Hu1, Hv1, Hw1, Hu2, Hv2, Hw2, H
u3, Hv3, Hw3 ... Hall element for position detection, Mg ...
Position detecting magnet, U +, V +, W +, U-, V
-, W-: switching element, Tmin1: minimum torque of two-phase energized three-phase brushless DC motor, Tmin2
... Minimum torque when a 3-phase reluctance motor is energized in 2 phases.

Claims (2)

[Claims] 1. A rotation angle of a rotor of a three-phase reluctance motor or an electrical angle from an arbitrary reference position at a position opposed to a position detection magnet mounted on a shaft rotating in synchronization with the rotor. 60 ° or 120
Three position detection Hall elements Hu so as to be spaced at an angle
1, Hv1 and Hw1 are arranged, and the electrical angle is 30 ° × (2n−) with respect to the position detecting Hall element Hu1.
1) The Hall element for position detection Hu2 is arranged so as to have a phase difference of (n is a natural number), and the Hall elements for position detection Hv2 and Hw2 are 60 ° or 120 electrical degrees with respect to the Hall element for position detection Hu2. A method for detecting the position of a three-phase reluctance motor, wherein the three-phase reluctance motor is disposed at an interval. 2. The control method for a three-phase reluctance motor according to claim 1, wherein energization is performed at an electrical angle of 150 ° based on a position detection signal obtained from the position detection Hall element.