JPS6360637B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control circuit for the rotation direction of a small synchronous motor, and in particular to a control circuit for the rotation direction of a single-phase coil synchronous motor, in which the rotation direction at startup can be freely controlled in forward and reverse directions. It is related to circuits.

Conventionally, means for determining the rotational direction of a synchronous motor include mechanical means, shading poles, magnetic pole arrangement, and capacitors. However, the above-mentioned mechanical means has the drawbacks of a complicated structure, noise, and reduced reliability due to wear. Furthermore, the method using shedding poles has the disadvantage that rotational direction control is incomplete and rotation becomes extremely unstable. The magnetic pole arrangement has the disadvantage that the rotation direction is fixed in one direction. Furthermore, the method using a capacitor requires a two-phase coil, which has the disadvantage of increasing the size and cost.

The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks,
An object of the present invention is to provide a rotational direction control circuit for a single-phase small synchronous motor that can freely and reliably control the rotational direction in the forward and reverse directions at the time of startup.

The present invention is characterized by determining the position of the rotor at startup by detecting its N and S polarities, and supplying AC power from its positive or negative cycle depending on the determined polarity. Regardless of when the AC power source is turned on, the AC power source is supplied from around the zero point at the beginning of the positive half cycle or negative half cycle of the AC voltage in accordance with the starting direction.

below. The invention will be explained by means of illustrated embodiments.

In FIGS. 1 and 2, a first case 1 that also serves as a yoke and has a cylindrical outer circumference;
A stator of the motor is constituted by a second case 2 that is fixed so as to cover this case, and a single-phase coil 3 that is fitted into the annular space formed by these cases 1 and 2. ing. The inner peripheral edges of the cases 1 and 2 are cut out at predetermined intervals, and the remaining parts are bent upward and downward, respectively, to form stator poles 1a and 2a, and these stator molds 1a and 2a are arranged alternately. They are arranged to mesh with each other with a predetermined gap, forming a cylindrical space 4 on the inner periphery of the stator. In this space 4, a cylindrical rotor 5, which is magnetized alternately with N poles and S poles in the circumferential direction of rotation, is disposed facing the stator poles 1a and 2a with a predetermined gap therebetween. ing. The rotating shaft 6 of the rotor 5 is supported by a bearing (not shown), and when an alternating current power is applied to the coil 3, the rotor 5 can rotate in synchronization with the alternating current. . A position detection plate 7 is fixed to the upper surface of the rotor 5, and has a light reflecting surface 7a and a non-reflecting surface 7b alternately formed in correspondence with the magnetic poles of the rotor 5. A reflective surface 7a corresponds to the north pole of the child 5, and a non-reflective surface 7b corresponds to the south pole. A detector 8 consisting of a light emitting diode and a phototransistor that receives light reflected from the diode and reflected by the detection plate 7 is provided above the position detection plate 7 . This detector 8
and the position detection plate 7 constitute a detection means for detecting the magnetic pole position. As shown in FIG. 3, when the single-phase coil 3 is supplied with a positive half-cycle current i+ of the AC power supply, the upper stator pole 2a becomes the N pole and the lower stator magnetic pole 1a is magnetized to the S pole, and vice versa when a negative half-cycle current i- is supplied. Further, the detector 8 is arranged at a position G such that the upper stator pole 2a is located on the left side and the lower stator pole 1a is located on the right side in the figure. However,
The detector 8 may be provided at a position H such that the lower stator pole 1a is located on the left side and the upper fixed pole 2a is located on the right side.

Next, a motor rotation direction control circuit configured as described above will be explained. In FIG. 4, the AC power supply 10 is applied to the DC power supply circuit 12, the positive trigger mode circuit 13, and the drive circuit 15 via the power switch 11, and the DC output of the DC power supply circuit 12 is in the positive trigger mode. circuit 13
and negative trigger mode circuit 14 and detection circuit 16. Regardless of when the switch 11 is turned on, the positive trigger mode circuit 13 rises at the beginning of the first positive half cycle of the AC power that arrives after the switch is turned on, and maintains this until the switch 11 is turned off. Also, the negative trigger mode circuit 1
4 receives a signal from the positive trigger mode circuit 13, rises at the beginning of the negative half cycle following the positive half cycle, and remains there until the switch 11 is turned off. The detection circuit 16 receives a signal of "1" or "0" from the detector 8 and outputs a signal of "1" or "0" to the output terminal Q. The output signal is applied to input terminals R and S of the trigger mode switching circuit 17 via a set of rotation direction switching switches 18. Here, the detection circuit 16 and the changeover switch 18 constitute a selection means for setting the supply start cycle of the power supplied to the single-phase coil 3 to either positive or negative. The trigger mode switching circuit 17 receives signals from the positive trigger mode circuit 13 and the negative trigger mode circuit 14, and supplies AC power 10 to the single-phase coil 3 from around the beginning of the cycle selected by the selection means. The operation start timing of the drive circuit 15 is controlled in this way. First, the drive circuit 15 supplies a positive half cycle or a negative half cycle of the AC power source to the single-phase coil 3 based on the selection result of the selection means.
Thereafter, the drive circuit 15 is operated alternately every positive and negative half cycle based on the signals from the two positive and negative trigger mode circuits 13 and 14, so that the drive circuit 15 is rotated in the direction corresponding to the switching mode of the switch 18. It's getting old. Therefore, the switching circuit 17 is
Either the trigger mode signal output from the trigger mode circuit 13 or the trigger mode signal output from the trigger mode circuit 14 is selected depending on the output signal of the detection means and the signal selected by the rotation direction changeover switch 18. Then, the start point of supplying AC power to the single-phase coil of the motor is the start point of the positive half cycle or the start point of the negative half cycle, and the rotor is turned in the direction selected by the rotation direction switch. It starts and rotates.

Specifically, the rotational direction control circuit is constructed as shown in FIG. In FIG. 5, the positive trigger mode circuit 13 includes resistors R ₁ and R ₂ that divide the voltage of the AC power supply 10, and a transistor Tr ₁ that operates on and off using the divided voltage as a base input.
, a delay circuit consisting of a resistor R ₃ and a capacitor C ₁ for slightly delaying the signal when the transistor Tr ₁ is on, and a delay signal from this delay circuit as a gate input to output an AC signal from the AC power supply 10. It has a thyristor SCR ₁ which is turned on by the first positive companion cycle, and a thyristor SCR 2 which is turned on by the turn-on of this thyristor SCR ₁ and outputs a signal of "1" from that point on based on the DC power supply ₁₂ . ing. Further, the negative trigger mode circuit 14 turns on and off the AC output signal of cycle SCR ₁ in the positive trigger mode circuit 13 as a base input, and turns on the DC output signal of the thyristor SCR ₂ in the positive trigger mode circuit 13. - It has a transistor Tr ₂ that turns off, and a thyristor SCR ₃ that uses the output signal of this transistor as a gate input to turn on and outputs a "1" signal based on the DC power supply 12 from that point on. Furthermore, when the detector 8 consisting of the light emitting diode LD and the phototransistor FT faces the reflective part 7a of the detection plate 7 as shown in FIG. Also, when the detector 8 faces the non-reflective portion 7b of the detection plate 7, the phototransistor
FT is turned off and a "1" signal is output. The detection circuit 16 includes a transistor Tr 3 which is turned on and outputs a signal of "0" when the output of the phototransistor FT in the detector 8 is "1", and a transistor Tr ₃ whose output is "0".
It has a transistor Tr ₄ that turns off and outputs a signal of "1" when . The output signal of the transistor Tr ₃ in the detection circuit 16 is connected to the common contact of one switching contact 18b of the rotation direction changeover switch 18, and the output signal of the transistor Tr ₄ is connected to the common contact of the other switching contact 18a. . The trigger mode switching circuit 17 includes a transistor Tr ₅ and a transistor Tr _6. When the switching contacts 18a and 18b are switched to the fixed contact X, the output signal of the transistor Tr ₃ is switched to the transistor Tr 6. ₆ and the output signal of transistor Tr ₄ is applied to the base of transistor Tr ₅ , respectively, and the switching contacts 18a, 18
Conversely, when b is switched to the fixed contact Y, the output of the transistor Tr ₃ is applied to the base of the transistor Tr ₅ , and the output of the transistor Tr ₄ is applied to the base of the transistor Tr ₆ . When the transistor Tr ₅ in the trigger mode switching circuit 17 is turned on, it passes the DC output signal from the thyristor SCR ₂ and converts it into the triac 1 constituting the drive circuit 15.
It is designed to be added to the gate of 5a, and
When the transistor Tr ₆ is turned on, it passes the DC output signal from the thyristor SCR ₃ and applies it to the gate of the triac 15a. Triack 15a
When turned on, AC power is supplied to the single-phase coil 3 of the motor.

Next, the operation of the rotation control circuit will be explained. By turning on the switch 11, a predetermined DC power is supplied from the power supply 12, and thereby the detector 8
When the light emitting diode LD inside lights up, the phototransistor FT starts detecting the light reflected from the detection plate 7. The voltage of the AC power supply 10 is divided by resistors R ₁ and R ₂ , and this divided voltage signal a is applied to the transistor
It is input to the base of Tr ₁ (see a in Figure 6).
Transistor Tr ₁ turns on only during the positive half cycle of the AC signal and outputs a "0" signal only while it is on, but since the voltage V _BE is actually required, it is shown in Figure 6b. As shown in the figure, it rises slightly before the end of the positive half cycle and falls slightly after the beginning of the positive half cycle, resulting in a narrower signal width for "0" and a wider signal width for "1". . The signal b of the transistor Tr ₁ is input to a delay circuit consisting of a resistor R ₃ and a capacitor C ₁ , and the timing of the rise of the signal is △t as shown in c of Figure 6.
is input to the gate of thyristor _SCR1 . The timing of the gate input of this thyristor SCR ₁ and the AC power supply applied between the anode and cathode is as shown in c and a of Figure 6. Since the cycle begins, thyristor SCR ₁ turns on every positive half cycle and its output signal d is at the sixth
As shown in d of the figure, among the positive and negative half cycles of the AC power input when the switch 11 is turned on, it always starts from the zero point at the beginning of the positive half cycle, and at the end of the positive half cycle. It is designed to end at the zero point of . Note that resistor R ₃ and capacitor C ₁
The reason for providing the delay circuit is that, as mentioned above, V _BE is required for transistor Tr ₁ to operate, and the sixth
As shown in figure b, transistor Tr ₁ rises quickly and falls slowly, so this signal b
If it is added to thyristor SCR ₁ as it is, the thyristor
This is to avoid the situation where the SCR ₁ turns on near the end of the positive half cycle of the AC power supply, making the rotation control unstable. The output d of thyristor SCR ₁ is applied to the gate of thyristor SCR ₂ . Since the DC power supply 12 is applied between the anode and cathode of thyristor SCR ₂ ,
The thyristor SCR ₂ is turned on and maintained at the same time as the start of the first positive half cycle of the signal d, and its output signal becomes ``1'' as shown in e of FIG. 6 and remains this way.

Since the output signal d of the thyristor SCR ₁ is applied to the base of the transistor Tr ₂ in the negative trigger mode circuit 14, the transistor Tr ₂ is turned on at the same time as the beginning of the positive half cycle of the signal d;
When the signal d reaches zero level, it is turned off, and its output signal f becomes "11" while the transistor Tr ₂ is off, as shown at f in FIG. However, in this case, the operation of transistor Tr ₂ requires V _BE
As a result, the on timing of the transistor Tr ₂ is delayed and the off timing is early. Therefore, the output signal f due to the on/off operation of the transistor Tr ₂ becomes a "0" signal as shown in f in Fig. 6. The signal width of "1" is wider than the width. This signal f is applied to the gate of thyristor _SCR3 . DC power supply 1 is connected between the anode and cathode of thyristor SCR ₃ .
2, the thyristor SCR ₃ turns on with the first rising edge of the signal f and remains there, so that the output signal g of the thyristor SCR ₃ becomes an alternating current, as shown in g of FIG. “1” approximately in synchronization with the start of the negative half cycle of the power supply.
And this will continue. Therefore, if the output signal e of the positive trigger mode circuit 13 and the output signal g of the negative trigger mode circuit 14 are compared, the signal g lags the signal e by approximately half a cycle of the AC power supply. ing. However, if it is synchronized with the cycle of the AC power supply, the signal g can be changed to the signal e.
It may be possible to advance the time by half a cycle.

Now, as shown in FIG.
However, if it faces the non-reflection part 7b provided corresponding to the S pole of the rotor 5, the phototransistor of the detector 8 is turned off, and its output signal h becomes "1". It's summery. This "1" signal is applied to the base of the transistor Tr ₃ in the detection circuit 16, turning on the transistor Tr ₃ and making its output "0". This "0" signal is added to the base of transistor Tr ₄ and
Turn off Tr ₄ and set its output to "1". Further, assuming that _each contact of the rotation direction changeover switch ₁₈ selects the added to the base and also the detection circuit 1
The output signal of the transistor Tr ₄ , which is the output Q of the transistor 6, is applied as the input signal R of the trigger mode switching circuit 17 to the base of the transistor Tr ₅ . Further, the output signal g of the negative trigger mode circuit 14 is applied to the collector of the transistor Tr ₆ , and the output signal e of the positive trigger mode circuit 13 is applied to the collector of the transistor Tr ₅ . The transistor Tr ₅ is turned on by applying a rising signal Q synchronized with the rising edge of the signal e to its base, and the output signal of the transistor Tr ₅ is the output signal of the thyristor SCR ₂ , that is, the output signal of the positive trigger mode circuit 13. It becomes the same as e. The triax 15a in the drive circuit ₁₅ is turned on by the output of the transistor Tr5, and AC power is supplied to the single-phase coil 3 of the motor via the triax 15a. Since the supply of this AC power is started in synchronization with the rising edge of the signal e, as shown in Fig. 6,
The supply will begin at the beginning of the positive half-cycle of the alternating current, as indicated by E ₁ .
Then, in the positive half cycle, as shown in FIG. 7, one stator pole 2a becomes the N pole,
Since the other stator pole 1a is magnetized to the S pole, a torque acting toward the left in FIG. 7 acts on the rotor 5, causing the rotor 5 to rotate in the forward rotation direction CCW.
Then, due to the positive half cycle, the rotor 5 rotates in the forward direction.
Rotate 45° CCW as shown in Figure 8.
The detector 8 is located at a position corresponding to the N pole of the rotor 5, and thus faces the reflecting portion 7a of the position detection plate 7, and the phototransistor FT receives the reflected light and turns on, and its output becomes " 0”. As a result, the output of the detection circuit 16 is "1", the Q is "0", the input S of the trigger mode switching circuit 17 is "1", and the input R is "0", so that the transistor Tr ₅ is turned off and the transistor Tr ₆ is turned off. The output of the negative trigger mode circuit 14 is applied to the triax 15a through the transistor Tr ₆ to continue turning on the triax 15a and supplying the negative half cycle of the AC power to the single-phase coil 3. As a result, as shown in Fig. 8, one stator pole 2a is magnetized to the S pole and the other stator pole 1a is magnetized to the N pole, which is the opposite of the case in Fig. 7, and the rotation continues. A torque toward the left in FIG. 8 acts on the child 5, causing it to rotate in the normal rotation direction CCW. From now on, repeat the above operation every time the rotor 5 rotates 45 degrees,
The single-phase coil 3 is supplied with an alternating current power such as _E1 in FIG. 6, and continues to rotate in the forward direction CCW in synchronization with this alternating current.

Next, a case will be described in which the rotation direction changeover switch 18 is switched to the contact point Y. Now, as shown in FIG.
If the detector 8 is opposed to the pole, the detector 8 is opposed to the non-reflective portion 7b of the detection plate 7, so the phototransistor FT is turned off and the output of the detection circuit 16 is "0", Q becomes "1",
The input S of the trigger mode switching circuit 17 is "1",
R becomes "0", transistor Tr ₆ is turned on, and transistor Tr ₅ is turned off. Transistor Tr ₆
The timing at which Tr is turned on is synchronized with the rise of the output signal g of the negative trigger mode circuit ₁₄ , and is approximately synchronized with the start of the negative half cycle of the AC power supply. The timing at which 15a is turned on is also substantially synchronized with the start of the negative half cycle of the AC power supply, and the single-phase coil 3 is turned on at the same time as the start of the negative half cycle of the AC power supply, as shown by _E2 in FIG. This negative half cycle is provided. As a result, as shown in FIG. 9, the stator pole 2a is magnetized to the S pole and the stator pole 1a is magnetized to the N pole, and the rotor 5 is driven to rotate in the reverse direction CW. When the rotor 5 reverses by 45 degrees in this way, the output signal of the detection circuit 16 is reversed based on the position detection operation of the detector 8, and the transistor Tr ₅ in the trigger mode switching circuit 17 is turned on, so that the drive circuit 15 Triack 15 inside
Continue to turn on a, try 15
The positive half-cycle of the alternating current supplied through a reverses the magnetization of the stator poles, as shown in FIG. 10, and the rotor 5 continues to rotate in the reverse direction CW. In this way, the above operation is repeated every time the rotor rotates by 45 degrees, and an alternating current as indicated by _E2 in FIG. 6 is applied to the single-phase coil 3 to maintain the reverse rotation.

The forward/reverse rotation described above is performed by the positive trigger mode circuit 1 while the switch 11 is on.
Since the trigger mode output signal e of No. 3 and the trigger mode output signal g of the negative trigger mode circuit 14 are maintained, the rotation is continued during that time, and the rotation is stopped by turning off the switch 11.

According to the present invention, the following effects that could not be achieved with conventional small synchronous motor rotation direction control means are achieved.

(1) Regardless of the rotor position at startup, if a desired rotation direction is determined by switching the rotation direction changeover switch, etc., the startup rotation can be automatically performed in that rotation direction.

(2) Since the polarity of the current to be passed through the stator is controlled based on the position of the rotor and the desired rotation direction, the reliability of rotation direction control is extremely high. Furthermore, since the AC power is supplied to the stator from around the beginning of the positive or negative half cycle, there is no instability in the rotation start and complete rotation control can be performed.

(3) Since the motor coil is a single-phase coil and no mechanical mechanism is added, the structure of the motor itself is extremely simple and its shape is small, making it easy to incorporate into small electronic devices. Also, production costs can be significantly reduced.

(4) Since everything is controlled by electric circuits, stopping, restarting, forward rotation, and reverse rotation can be freely controlled according to a preset program by combining it with an appropriate programming device. It is also possible to repeat a predetermined program any number of times.

(5) The detector can also be used as an encoder to control other devices attached to the motor, such as precision movement devices.

Note that the AC power source used in the present invention is not limited to a sine wave AC power source, but may also be a square wave or any other AC power source. The detector may be an optical one, a magnetic one using a Hall element, a magnetoresistive element, etc., or any other means that can determine the polarity of the rotor. Also,
The input of the negative trigger mode circuit 14 may also be provided with a delay circuit as seen in the positive trigger mode circuit 13.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the mechanical components of the motor of the present invention, FIG. 2 is a plan view of the same, and FIG.
The figure is a developed diagram showing the relationship between the current supplied to the coil in the mechanical component and the magnetization effect of the stator poles; FIG. 4 is a block diagram showing an example of the electrical control circuit used in the present invention; Fig. 5 is a circuit diagram showing a specific example of the above control circuit, Fig. 6 is a timing chart for explaining the operation of the above control circuit, and Figs. 7 to 10 are rotor diagrams for explaining the operation of the above control circuit. FIG. 3 is a development diagram showing a simplified relationship between the detector and the stator poles. 1a, 2a...Stator pole, 3...Single phase coil,
5...Rotor, 7...Position detection plate, 7a...Reflection part, 7b...Non-reflection part, 8...Detector, 10...
AC power supply, 11... switch, 12... DC power supply, 13... positive trigger mode circuit, 14...
Negative trigger mode circuit, 15... Drive circuit, 1
6...Detection circuit, 17...Trigger mode switching circuit, 18...Rotation direction switching switch, 7, 8...
Detection means, 13, 14, 15, 17... Power supply means, 16, 18... Selection means.

Claims (1)

[Scope of Claims] 1. A rotor in which N and S poles are alternately magnetized in the circumferential direction of rotation, and a stator in which a single-phase coil is wound around the rotor, which is disposed facing the rotor with an air gap interposed therebetween. A first trigger mode circuit that outputs a first trigger mode signal that rises at the beginning of one half cycle that first arrives after turning on the AC power; a second trigger mode circuit that outputs a second trigger mode signal that rises at the beginning of the other half cycle that arrives at the second half cycle; a detection means that detects the magnetic pole position of the rotor; and a detection means that detects the magnetic pole position of the rotor according to the rotation direction of the motor. a rotational direction switching switch that switches and outputs the polarity of an output signal of the means; a drive circuit that supplies the alternating current power to a single-phase coil of the motor; an output signal of the rotational direction switching switch and the first trigger mode signal. and a trigger mode switching circuit that inputs the trigger mode signal and the second trigger mode signal to control the drive circuit.