JPS6253186A - Method of driving small-sized synchronous motor - Google Patents

Abstract

PURPOSE:To regulate the direction of rotation of a rotor in one direction at all times even when source frequency changes by making the phase of frequency in case of starting or stoppage different from that in case of driving by other frequency. CONSTITUTION:A synchronous motor 1 is connected to a power supply 3 at 50Hz or 60Hz through a Triac 2 for switching. A control circuit 5 generates a gate signal S at a 'H' level for a driving period (t). The starting time t1 of the generation of the gate signal has the same phase at both supply voltage E1 of 50Hz frequency and supply voltage E2 of 60Hz frequency, and is given on a voltage value of 0. The stopping time t2 thereof is set at the time of mutually inverted phase between supply voltage E1 and E2.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for driving a small synchronous motor, and particularly to means for always regulating the motor in a certain direction of rotation even when driven by power sources of different frequencies.

BACKGROUND OF THE INVENTION In principle, an inductor type small synchronous motor has the characteristic of being able to rotate in any direction.

Therefore, this inductor type small synchronous motor usually incorporates a mechanical reverse rotation prevention mechanism or a shading pole for regulating the rotation direction.

BACKGROUND OF THE INVENTION By the way, the above-mentioned small synchronous motor is usually connected to a commercial power supply, turned on at the zero point of the power supply voltage by a switching element such as a triac, and turned off after a cycle of a certain integral multiple of the power supply frequency. , during which the necessary rotational force is applied to the load.

In general, in this on/off control, there is no difference in the control method depending on the change in the power supply frequency. For this reason, even if this small synchronous motor is driven for the same integer multiple of the cycle or for the same time, the rotor's rotational speed, or inertia, will differ depending on the power supply frequency at the time of stopping, so the phase of the frequency at the time of stopping will be different. Even if they are exactly the same, different frequencies will cause a difference in the stopping phase of the rotor.

For example, at a low commercial frequency (50Hz), the rotor vibrates a little and then stops almost as soon as the power supply voltage is turned off, whereas at a high commercial frequency (60Hz), from the moment the power supply voltage is turned off, the rotor moves due to inertia to the magnetic pole group. 1, i.e. 180 in electrical angle of the power supply frequency.
' It rotates an extra half cycle and then stops. Therefore, in the case of a power supply voltage of 50Hz, rotation in the same direction is obtained at the next startup, whereas with a power supply voltage of 60Hz, the rotor rotates in the opposite direction due to the phase shift of the rotor at startup. It turns out. As a result, at startup, the actuating lever for preventing reverse rotation hits the stopper of the rotor, producing an impact sound. In applications where this impact noise is considered a problem, a solution to this problem is desired.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to make it possible to always regulate the rotational direction of the rotor in a certain direction even when the power frequency of a small synchronous motor is changed.

Solution to the Invention Therefore, the present invention focuses on the inertial rotation of the rotor with respect to the magnetic pole group using a high frequency power supply, and sets the phase of the power supply frequency at the time of stop to an electrical angle, and changes the phase by 180° (half period) to another lower The frequency is set to be different from the power supply phase. Such a phase setting relationship can be similarly set for the frequency phase at the start time as well as at the stop time. In other words, the driving period is an integer multiple of the period at low frequencies,
Furthermore, at low frequencies, the frequency is an integer + 0.5) times the period.

As a result, when stopped by a high frequency power supply, the rotor rotates by one pole, that is, an additional 180 degrees in electrical angle from the point of stop, and then stops at the same stop phase as when starting. It turns out. therefore,
Even at subsequent startups, it will always be regulated in the same direction regardless of changes in the power supply frequency.

Configuration and Function of Drive Circuit First, FIG. 1 shows the drive circuit. The small synchronous motor 1 to be controlled is a triac 2 for switching.
It is connected to a 50 Hz or 60 Hz power source 3 via. The power supply 3 is also connected to a control circuit 5 via a control power supply circuit 4. This control circuit 5 is
By applying a control signal to the control terminal of the triac in synchronization with the frequency of the power source 3, the tritic is turned on for a predetermined drive period, and the small synchronous motor 1 is driven during that period. do. Since this drive period is regulated by time or phase depending on each embodiment, the control circuit 5 has a timekeeping function or a phase identification function. However, these functions can also be shared by an external control system.

Embodiment 1 Next, FIG. 2 shows a control method according to Embodiment 1 of the present invention. The control circuit 5 maintains “H” over the drive period t.
A level gate signal S is generated. The starting point t is the power supply voltage E1 with a frequency of 50Hz and 60H.
Both are in the same phase with respect to the power supply voltage E2 of z and are applied when the voltage value is 0.

Further, the stop time t2 is set at a time when the power supply voltages E, E, and E are in opposite phases to each other.

That is, at the power supply voltage E1 of 50 Hz, the relationship is set such that the period is an integral multiple of one period T. On the other hand,
At a power supply voltage E2 of 60 Hz, one period T of (integer + 0.
5) It is set to double. In this way, the power supply voltage El,
For each Et, the phase of the frequency at the time of stop is 1 in electrical angle.
It is set to be shifted by 80° (half cycle).

Next, FIG. 3 shows the relationship between the stop phase of the rotor and the starting direction. The rotor 6 of this specific example has 1 along the circumference.
/10, and each pole is magnetized alternately with the NS pole. As a result, the rotor 6 stops at two positions A and B in FIG. 3 with respect to the stator poles 7.

Note that this rotor 6 rotates synchronously at a center angle of 72 degrees per period T of the power supply voltages E1 and E2, so the phase difference at the stop position of 2p is 18 degrees in electrical angle (half cycle). .

Now, when a power supply voltage E1 of 50 Hz is applied to the stator pole 7 in the state shown in FIG. 3A at the start, the rotor 6 rotates clockwise. Or, since the magnetization of the stator pole 7 is set at time t2 at 71 in a reverse relationship to that at the start time t, the rotor 6 will definitely stop again in the state shown in FIG. 3A.

At this time, since the rotor 6 does not have inertial rotation that rotates by one pole, the rotor 6 stops at that position while vibrating a little without overrunning. Therefore, at the next start time t1, the power supply voltage E1 is also in the same phase.
is applied, the rotor 6 will rotate in the same clockwise direction.

On the other hand, with a power supply voltage E of 60Hz, the third
In the state shown in Figure A, the 50Hz power supply voltage E is applied with the same polarity, so the rotation direction is also set to the same clockwise direction.At the stop time t'2, the 50Hz power supply voltage E
The phase is different from I by half a cycle. In other words, the rotor 6 rotates more by one pole than at 50 Hz, and loses the power supply voltage E2. Moreover, at this time,
Due to the high frequency, the rotor 6 is rotating at a rotation speed higher than the rotation speed at 50Hz, so due to its inertial rotation, the rotor 6 is rotated by one pole of the rotor 6, that is, 180' (half period) in electrical angle. It stops in an overrun state and is set to the same rotational phase as when it started. As a result, the rotor 6 has a total of two poles (rotation angle of 72°), one pole due to the half cycle of the power supply voltage Et and one pole due to inertial rotation, compared to when the power supply voltage El is applied. It rotates a lot and ends up in the same phase as when it started. For this reason,
In this case as well, the rotor 6 does not stop in the state shown in FIG. 3B. Therefore, if the power supply voltage E with the same polarity is applied at the next startup, the rotor 6 will still rotate clockwise. Identification of the power supply frequency and setting of the driving time t are performed by the control circuit 5 or are set in advance by external operation. Note that the drive period t is approximately 400 msec, and the respective power supply voltages E, , E, and the number of rotations of the rotor 6 are within 4 rotations.

Embodiment 2 In the above embodiment 1, a common reversal time is selected for the phases of the power supply voltages E, , E, and the drive time t is set constant. However, in this embodiment 2, the power supply voltages E+, Ex A different driving time t is set for each. Again, starting point 1. Although the phases of the power supply voltages E+ and Ez are set to be the same, the phases of the power supply voltages E+ and Ez at the stop time t2 are set in a different relationship. In this example,
Driving time t is 3t for one cycle of each power supply voltage EI, E2
It can be set freely for each JIT, which is advantageous for adjusting the rotation speed.

Embodiment 3 This embodiment sets the phase of the stop time t2 to be the same for the supply voltages E, , E, as shown in FIG.
An example is shown in which different phases are set for + and Ez. With the power supply voltage E2 of this embodiment, the rotor 6 is at a stopped position as shown in FIG. Therefore, the rotor 6 will still rotate clockwise.

In this embodiment, if the power supply voltages E+ and Ex are changed continuously in the middle, reverse rotation will occur, so such operation is prohibited.

Embodiment 4 Next, in the embodiment shown in FIG. 6, when the power supply voltage E1 is applied, voltage is applied with the same phase as in Embodiment 1, whereas 60
In the case of the power supply voltage E2 of Hz, this is an example in which the power supply voltage E2m is applied at a certain start-up, and the power supply voltage Ezb having the opposite phase is applied at the next start-up. When a power supply voltage of 22 m is first applied, the stopping phase of the rotor 6 is shifted by one pole from the starting phase, which is 180 electrical degrees.
However, during subsequent startup, the stator poles 7 are excited with the same polarity as at the previous stop, so the rotor 6 ends up moving in the same direction. The drive time is set to a cycle that is an integral multiple of the frequency of the power supply voltages E+ and Ez in both cases.In this example, changing the frequency of the power supply 3 midway is also prohibited. Ru.

Modifications of the Invention For convenience of explanation, the above embodiment shows an example in which the rotor 6 is rotated clockwise, but the rotation direction may always be in one direction, and may also be set in a counterclockwise direction. .

Therefore, the polarity of the power supply voltage at the time of starting and stopping may have a reverse relationship with that of each embodiment.

Furthermore, even if the 50 Hz control and the 60 Hz control in each of the above embodiments are reversed, they can be regulated in the same direction depending on the polarity and inertial rotation characteristics of the rotor 6. and,
The inertial rotation is the same for odd numbered poles.

Furthermore, the frequency of the power supply is commercial frequency (5011z, 6
It is not limited to 0Hz), but can also be applied to 30Hz, 40Hz, etc. by converting the frequency using an inverter.

Furthermore, the triac 2 maintains its conductive state even if it loses the gate signal S at a point higher than a certain voltage value in a half cycle, so the OFF point of the gate signal S changes to some extent within the range of a half cycle of the power supply voltage. Also, since the triac 2 always turns off at the O level of the voltage of the power supply 3, the turning-on point of the gate signal S can be adjusted within that range. Of course, the power supply voltage is not limited to two different frequencies, but may be more than two different frequencies.

Effects of the Invention In the present invention, at least one of the phase of the frequency at the time of starting and the phase of the frequency at the time of stopping is made different from that when driving at other frequencies, depending on the frequency of the power supply voltage. Even if the power supply frequency changes, the rotation direction of the rotor can always be regulated to one direction, so there is no need for a reverse rotation prevention mechanism, and even if it is incorporated, collision noise etc. will not occur during reverse rotation. It can be prevented.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of the drive circuit of a small synchronous motor, Fig. 2 is a waveform diagram of the power supply voltage in Example 1, Fig. 3 is an explanatory diagram of the relationship between the stop phase of the rotor and the starting direction, and Fig. 4 6 through 6 are power supply voltage waveform diagrams in other embodiments, respectively. 1. Small synchronous motor, 2. Triac, 3. Power supply, 4. Power supply circuit, 5. Control circuit, E3, E2 ・
- Power supply voltage, S...gate signal, tl...start time, tt...stop time. Patent applicant Sankyo Seiki Seisakusho Co., Ltd.
Patent Attorney Kunio Nakagawa Figure 7 Figure 2

Claims (1)

[Claims] In a small synchronous motor driven by a power source with multiple frequencies, when driving at one frequency, at least one of the phase of the frequency at the start and the phase of the frequency at the time of stopping is changed to another frequency. A method for driving a small synchronous motor, characterized in that the driving method is different from that when the motor is being driven.