JP4428939B2 - Single-phase AC synchronous motor drive device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a driving device for a single-phase AC synchronous motor.
[0002]
[Prior art]
In self-starting a single-phase AC synchronous motor (hereinafter simply referred to as a synchronous motor), various methods have been proposed such as using a starting capacitor and a starting auxiliary winding to obtain a sufficient starting torque for the starting. Yes.
[0003]
In addition, when a large starting torque is required, a method has been proposed in which the synchronous motor is disconnected from the load at the time of starting and connected to the load after the synchronous operation in order to ensure the starting.
[0004]
However, these methods not only increase the cost, but also have problems in terms of sound and reliability due to mechanical switches.
[0005]
As a starting device for starting this synchronous motor, the following is proposed (Patent Document 1).
[0006]
The starting device has a triac arranged in series between the stator winding of the synchronous motor and the AC power source, and the triac is configured to reduce the current flowing through the stator winding of the synchronous motor and the rotor. It is controlled by an electronic circuit that processes the position and polarity of the permanent magnet and the polarity of the AC voltage source.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-78583
[Problems to be solved by the invention]
In the starting device of Patent Document 1 as described above, when the rotor responds quickly to the excitation of the stator windings, the synchronous motor repeats the instantaneous locked state, causing vibration and noise. There is a problem.
[0009]
Therefore, in view of the above problems, the present invention provides a drive device that is low in cost and can suppress vibration and noise when starting a single-phase AC synchronous motor.
[0010]
The invention according to claim 1 is a permanent magnet type single-phase AC synchronous motor driving device comprising two rotor poles and two stator poles, wherein the AC power is applied to the stator winding wound around the stator. Power supply polarity detection means for determining the polarity of the applied voltage, magnetic pole detection means for detecting the position of the magnetic pole of the rotor composed of S and N poles, and the stator winding and the AC power supply are connected in series. The TRIAC is turned ON / OFF by outputting a gate trigger signal based on the triac, the polarity determination signal from the power supply polarity detection means, and the magnetic pole determination signal from the magnetic pole detection means, and the rotation direction of the rotor And a control means for exciting the stator winding so as to generate a torque to the direction from the zero cross point of the voltage of the AC power supply, θ1 (where 0 ° = <θ1 <90 ° There is a delay gate ON the trigger signal, the more the zero-crossing point .theta.2 (however, 90 ° <θ2 = <a 180 °) By OFF of the gate trigger signal is delayed, .theta.1 or .theta.2 less than the zero-crossing point the phase of the AC power source and A drive device for a single-phase AC synchronous motor, characterized by being controlled .
[0011]
According to a second aspect of the present invention, there is provided a single-phase AC synchronous motor driving apparatus according to the first aspect, wherein a gap between the stator and the rotor is not uniform.
[0012]
[Operation]
A drive device for a single-phase AC synchronous motor according to claim 1 will be described.
[0013]
At the time of starting the single-phase AC synchronous motor, the control means outputs a gate trigger signal based on the polarity judgment signal from the power source polarity detection means and the magnetic pole judgment signal from the magnetic pole detection means to turn the triac on / off. The stator winding is excited so that torque in the rotation direction of the rotor is generated. In this case, the control means turns on the gate trigger signal with a delay of θ1 from the zero cross point of the voltage of the AC power supply, and turns off the gate trigger signal with a delay of θ2 from the zero cross point.
[0014]
As described above, the gate trigger signal is turned on by delaying θ1 and turned off by delaying θ2 to thereby suppress vibration and effectively start the single-phase AC synchronous motor.
[0015]
In the drive device for the single-phase AC synchronous motor according to claim 2, by making the gap between the stator and the rotor non-uniform, the starting torque is increased in the portion where the gap is small, and the starting is easy.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a driving device for a single-phase AC synchronous motor (hereinafter simply referred to as a synchronous motor) of the present invention will be described.
[0017]
(1) Principle of Synchronous Motor First, before describing the contents of the present embodiment, regarding the principle of the synchronous motor (single-phase AC synchronous motor), the equivalent circuit of the synchronous motor of FIG. 6 and the instantaneous voltage in the equivalent circuit of FIG. The waveform of the instantaneous current will be described with reference to the vector diagram of FIG.
[0018]
FIG. 6 is an equivalent circuit of a synchronous motor, and the content of the equivalent circuit can be expressed by the voltage equation (1).
[0019]
V = (r + PL) Im + E0 (1)
However, P is a differential operator.
[0020]
That is, the voltage difference between the voltage V and the induced voltage E0 applied to the synchronous motor is added to the winding resistance r and the synchronous inductance L, and the motor current Im flows. FIG. 7 shows waveforms of the instantaneous voltage and instantaneous current.
[0021]
When the phase relationship of the waveforms in FIG. 7 is expressed in an orthogonal coordinate system, the vector diagram in FIG. That is, since the induced voltage E0 has a leading phase of 90 ° with respect to the rotating magnetic flux, when the rotor magnetic flux axis (d axis) and the induced voltage axis (q axis) are selected with the counterclockwise direction being positive, this d In the -q coordinate system, the voltage and current sine wave peak values are lengths, and the phase difference is expressed as an angle difference. The motor voltage V is expressed by the sum VS of voltages applied to the induced voltage E0, the winding resistance r, and the synchronous inductance L from the equation (1). Further, this VS is decomposed into a voltage drop VR due to the winding resistance r, which has the same phase as the motor current Im, and a voltage drop VL due to the synchronous inductance L having a lead phase of 90 ° from that.
[0022]
(2) Start Control Method Next, as shown in FIG. 1, a rotor 14 is rotatably arranged between U-shaped stators 12, and is composed of two rotor poles and two stator poles. A starting control method for the magnet-type single-phase AC synchronous motor will be described.
[0023]
In order to rotate the synchronous motor 10, it is necessary to excite the stator winding 16 so as to generate a magnetic flux that generates a torque in the rotational direction. For example, in the case of the state shown in FIG. 1, the torque in the rotational direction (counterclockwise) in the figure is obtained by exciting the stator winding 16 so that the magnetic flux φ is generated in the direction of the arrow in the figure. The synchronous motor 10 generates a rotational force. In addition, when the rotor pole is in the opposite position, excitation may be performed so as to generate a magnetic flux in the direction opposite to the arrow in the figure.
[0024]
Specifically, in FIG. 1, if the AC1 terminal of the AC power supply 18 has a higher potential than the AC2 terminal, and the direction of the magnetic flux generated when the stator winding 16 is energized in this state is the left direction of the figure, the rotor If the pole is at a position where it repels the magnetic flux generated by the stator and is tilted in the rotational direction, the synchronous motor 10 generates a rotational force in the direction shown in FIG.
[0025]
In order to realize this, whether the polarity of the AC power supply 18 is detected, the polarity of the rotor pole is detected using a magnetic pole sensor such as a Hall IC, and the stator winding 16 can be excited from these mutual relationships. Decide whether or not. These interrelationships differ depending on the winding direction and rotation direction of the stator winding 16, and are conventionally summarized in the following two patterns.
[0026]
The conventional first excitation pattern is a case where the polarity of the AC power supply 18 is positive and the rotor magnetic pole is N, or the polarity is negative and the rotor magnetic pole is S, as shown in FIG.
[0027]
The conventional second excitation pattern is a case where the polarity of the AC power supply 18 is positive and the rotor magnetic pole is S, or the polarity is negative and the rotor magnetic pole is N, as shown in FIG.
[0028]
An appropriate pattern is selected from these two conventional excitation patterns in accordance with the structure of the synchronous motor 10.
[0029]
However, even with these two conventional excitation patterns, vibration may occur.
[0030]
The reason for this is that, as shown in the conventional example of FIG. 9A, when the response of the rotor 14 is fast with respect to the excitation to the stator winding 16, the synchronous motor repeats the instantaneous lock state. . That is, as shown in the graph of FIG. 9A, the rotation starts when the AC power source 18 passes through the zero cross point, and the point when the rotation of the rotor 14 is terminated by the torque is the F point. This is because a voltage is applied between the point F and the next zero-cross point, but the rotor 14 does not rotate, and thus a lock vibration period occurs.
[0031]
In the case of the conventional example of FIG. 10A, since the AC power supply 18 is in the ON state between the zero cross point and the F point after the zero cross point, the interval between the F point and the zero cross point is described above. Is in a state where a useless voltage is consumed. The “zero cross point” is a point at which the value of the AC voltage becomes zero.
[0032]
(3) Start Control Method of the Present Embodiment As described above, in the conventional start control method, there is a lock vibration period, and there is a useless voltage loss. A start control method that solves this problem is proposed.
[0033]
As described in the principle of the synchronous motor (1), the instantaneous waveforms of the AC applied voltage V, the induced voltage E0, and the motor current Im during synchronization are shown in FIG. 7, and the vector diagram thereof is as shown in FIG. Here, paying attention to the phase difference between the AC applied voltage V and the motor current Im, in the synchronous motor 10, the phase difference does not exceed 0 ° and does not exceed 90 ° due to the inductive load. Therefore, if a triac is used as an energization switch for the synchronous motor 10, energization in both directions is possible, and a signal at the energization ON timing may be given without turning off until the current becomes lower than the holding current.
[0034]
Therefore, in this embodiment, instead of the conventional first and second excitation patterns, as shown in FIGS. 5C and 5D, the energization start phase is set to θ1 (where, 0 ° = <θ1 <90 °), and the timing of turning off the gate trigger signal is set to a position delayed by θ2 (however, 90 ° <θ2 = <180 °) from the zero cross point. The synchronous motor 10 which suppresses vibration and also has a small electric power is started.
[0035]
In the first excitation pattern of the present embodiment, as shown in FIG. 5C, the polarity of the AC power supply 18 is positive and the phase thereof is not less than θ1 and not more than θ2 from the zero cross point, and the rotor magnetic pole has N or polarity. Is negative and the rotor magnetic pole is S.
[0036]
In the second excitation pattern of the present embodiment, as shown in FIG. 5D, the polarity of the AC power supply 18 is positive and the phase is θ1 or more and θ2 or less from the zero cross point, and the rotor magnetic pole is S or polarity. Is negative and the rotor magnetic pole is N.
[0037]
By delaying θ1 in this way, as shown in FIG. 9B, the rotation of the rotor 14 starts at the point G, and the rotation of the rotor 14 stops at the position of the zero cross point. There is no vibration period, and vibration can be suppressed.
[0038]
Further, by delaying θ2, unnecessary gate loss can be suppressed as shown in FIG.
[0039]
Θ1 and θ2 described above are determined by the mechanical time constant TM of the synchronous motor. The mechanical time constant TM (seconds) is the time required for the synchronous motor alone to apply a constant voltage and accelerate the motor speed to 63% of its saturation value by disconnecting the load.
[0040]
However, if it is difficult to determine θ1 and θ2 from the mechanical time constant of the synchronous motor, θ1 and θ2 with the least vibration may be obtained based on experiments.
[0041]
(4) Structure of Stator 12 and Rotor 14 The structure of the stator 12 and the rotor 14 for realizing the start control method will be described.
[0042]
As described above, the stator 12 is U-shaped, and more specifically, the stator windings 16 and 16 are wound around the opposing portions of the U-shaped stator core 20, respectively. A rotor 14 composed of an S pole and an N pole of a permanent magnet is rotatably disposed inside an arc-shaped cutout provided in the vicinity.
[0043]
In order to obtain the rotational force in the direction intended by the rotor 14, as shown in FIG. 2, the shape of the arc-shaped notch near the tip of the stator core 20 is an ellipse instead of a perfect circle. That is, the gap between the rotor 14 having a perfect circle and the elliptical notch is a non-uniform gap, and a difference is provided between the minimum gap a and the maximum gap b. For example, when the diameter R of the rotor 14 is 21 mm, the minimum gap is 1.9 mm and the maximum gap is 2.4 mm.
[0044]
If tilted by an arbitrary angle in advance, the synchronous motor 10 can be easily rotated in an intended direction (for example, counterclockwise direction) due to the torque difference in the non-uniform gap.
[0045]
In the above description, the arc-shaped notch of the stator core 20 is an ellipse, not a perfect circle. Instead, the arc-shaped notch shape near the tip of the stator core 20 is a perfect circle. However, as shown in FIG. 3, the rotor 14 may have a non-uniform gap as a cross section that is not a perfect circle but an ellipse in which the opposing portions bulge.
[0046]
(5) Driving device 22 for synchronous motor 10
A drive device 22 of the synchronous motor 10 for realizing the start control method will be described with reference to FIG. FIG. 4 is a block diagram of the driving device 22.
[0047]
A triac 24 is connected in series to the pair of stator windings 16, 16 of the synchronous motor 10, and an AC power supply 18 is connected to the triac 24 and one stator winding 16.
[0048]
In order to detect the rotational position of the rotor 16, a Hall IC 28 is disposed in the vicinity of the rotor 16 and outputs a magnetic pole determination signal. The control circuit 26 of the synchronous motor 10 receives a magnetic pole determination signal from the Hall IC 28.
[0049]
A power polarity detection circuit 30 for determining the polarity of the AC power supply 18 is provided, and a polarity determination signal from the power polarity detection circuit 30 is also input to the control circuit 26.
[0050]
Based on the first or second excitation pattern of the present embodiment described above, the control circuit 26 sends a gate trigger signal to the gate of the triac 24 via the gate trigger pulse generation circuit 32 to start rotation of the synchronous motor 10. Is output to the terminal.
[0051]
In the case of this driving device 22, the gate trigger signal is set so as to match the first or second excitation pattern of the present embodiment based on the magnetic pole determination signal from the Hall IC 28 and the polarity determination signal from the power supply polarity detection circuit 30. The synchronous motor 10 is started by outputting.
[0052]
(5) Due to the effects of the present embodiment, in the synchronous motor 10 of the present embodiment, the gate trigger signal is turned on by delaying θ1 from the zero cross point of the voltage of the AC power supply 18, and the gate trigger signal is delayed by θ2 from the zero cross point By turning OFF, it is possible to start the synchronous motor 10 that can suppress vibrations and suppress power loss.
[0053]
Further, by making the gap between the rotor 14 and the stator 12 non-uniform, the rotor 14 can be easily rotated in the intended direction.
[0054]
【The invention's effect】
As described above, the driving circuit for the single-phase AC synchronous motor of the present invention can be started with low vibration and low power loss.
[0055]
Further, the rotor can be easily rotated in the intended direction.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a structure of a synchronous motor according to an embodiment.
FIG. 2 is a diagram illustrating a structure of a stator and a rotor according to the present embodiment.
FIG. 3 is a longitudinal sectional view of a rotor having an elliptical cross section.
FIG. 4 is a block diagram of a synchronous motor driving apparatus according to the present embodiment.
FIGS. 5A and 5B are graphs showing a voltage waveform of an AC power source, a rotor magnetic pole and a triac gate trigger signal, wherein FIG. 5A is a conventional first excitation pattern, and FIG. 5B is a conventional second excitation pattern. (C) is a graph which shows the 1st excitation pattern of this embodiment, (d) is a graph which shows the 2nd excitation pattern of this embodiment.
FIG. 6 is an equivalent circuit of a synchronous motor.
FIG. 7 is a waveform diagram of instantaneous voltage and current in an equivalent circuit of a synchronous motor.
8 is a vector diagram in FIG. 7 as well.
FIGS. 9A and 9B are explanatory diagrams for explaining the contents of θ1, FIG. 9A is a conventional example, and FIG. 9B is a diagram of the present embodiment;
10A and 10B are diagrams for explaining θ2, in which FIG. 10A is a conventional example, and FIG. 10B is a diagram of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Synchronous motor 12 Stator 14 Rotor 16 Stator winding 18 AC power supply 20 Stator iron core 22 Drive device 24 Triac 26 Control circuit 28 Hall IC
30 Power supply polarity detection circuit 32 Gate trigger pulse generation circuit

Claims (2)

In the driving device of a permanent magnet type single-phase AC synchronous motor comprising two rotor poles and two stator poles,
Power supply polarity detection means for judging the polarity of the voltage applied to the stator winding wound around the stator from the AC power supply;
Magnetic pole detection means for detecting the position of the magnetic pole of the rotor composed of the S pole and the N pole;
A triac connected in series between the stator winding and the AC power source;
Based on the polarity determination signal from the power supply polarity detection means and the magnetic pole determination signal from the magnetic pole detection means, a gate trigger signal is output to turn the triac on / off, and torque in the rotation direction of the rotor is increased. Control means for exciting the stator windings to occur;
Have
The control means includes
The gate trigger signal is turned on with a delay of θ1 (where 0 ° = <θ1 <90 °) from the zero cross point of the voltage of the AC power supply, and θ2 (where 90 ° <θ2 = <180 ° from the zero cross point). A drive device for a single-phase AC synchronous motor characterized in that the phase of the AC power supply is controlled to be θ1 or more and θ2 or less from the zero cross point by delaying and turning off the gate trigger signal. The single-phase AC synchronous motor driving apparatus according to claim 1, wherein a gap between the stator and the rotor is not uniform.

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