JP3062638B2 - Single phase induction motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-phase induction motor.

[0002]

2. Description of the Related Art As shown in FIG.
0 is an auxiliary winding 1 to provide a phase difference between the current flowing through the main winding 112 and the current flowing through the auxiliary winding 114.
14, a phase advance capacitor 116 is connected in series. Then, the main winding 112 is connected in parallel to the phase-advancing capacitor 116 and the auxiliary winding 114 connected in series, and an AC power supply is connected to the main winding 112 and the auxiliary winding 114. The main winding 112 and the auxiliary winding 11
In order to control the current flowing through the AC power supply 4, an AC switch 122 composed of a bidirectional thyristor is connected in series with the AC power supply.

Then, the ON / OF of the AC switch 122 is turned on.
By controlling F, the main winding 112 and the auxiliary winding 1 are controlled.
14 and the phase control of the current flowing through the circuit.

[0004]

In the single-phase induction motor 100 having the phase-advancing capacitor 116 as described above,
For example, when the single-phase induction motor has two poles, the main winding 11
2 and the auxiliary winding 114 have the same magnetic flux density, ideally 90 degrees in both electrical angle and mechanical angle, and ideally also have a phase difference of 90 degrees.

When the rotation speed of the single-phase induction motor is changed, the voltage applied to the main winding 112 and the auxiliary winding 114 is changed by the AC switch 122. That is, when it is desired to increase the rotation speed, the AC switch 12
2 to increase the voltage applied to the main winding 112 and the auxiliary winding 114 and reduce the rotation speed, the AC switch 1
22 reduces the voltage applied to the main winding 112 and the auxiliary winding 114. In adjusting the rotation speed, the phase difference between the main winding 112 and the auxiliary winding 114 needs to be maintained at 90 °.

However, under the control of one AC switch 122, the current and the phase relationship between the main winding 112 and the auxiliary winding 114 are not well controlled, resulting in reduced efficiency and noise and vibration. Was.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a single-phase induction motor capable of controlling the currents flowing through the main winding and the auxiliary winding and the phase difference between these currents.

[0008]

A single-phase induction motor according to the present invention is a single-phase induction motor in which a main winding is connected in parallel to an auxiliary winding and a phase advance capacitor connected in series. ON / OFF the current flowing through the winding and auxiliary winding
A first switch, which is a bidirectional thyristor, and ON / O only a current connected in series with the main winding and flowing through the main winding.
A second switch including a bidirectional thyristor that performs FF, a first control unit that controls ON / OFF of the first switch,
And second control means for controlling ON / OFF of a second switch, wherein the first control means includes an input voltage of the AC power supply.
At a predetermined time during the half cycle of
And the second control means outputs the input command.
At a predetermined time during a half cycle of the force voltage, the second switch
Command to turn ON, and the ON
The command to be turned on is the same as the command to turn on the first control means.
Or later .

[0009]

According to the single-phase induction motor having the above structure, the current flowing through the main winding and the auxiliary winding is controlled by the first control means for controlling the first AC switch. Is controlled solely by the main winding by the second control means for controlling the second AC switch.

Thus, the second switch is connected to the first switch.
Because the main winding current does not turn on earlier than
Since the phase does not advance beyond the auxiliary winding current, the efficiency of the single-phase induction motor can be increased.

[0011]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a control circuit of a single-phase induction motor showing one embodiment of the present invention.

Reference numeral 10 denotes a single-phase induction motor, which has a main winding 12 and an auxiliary winding 14.
The phase advance capacitors 16 are connected in series. Main winding 1
2 is a second AC switch 1 comprising a bidirectional thyristor
8 are connected in series. The auxiliary winding 14 and the phase-advancing capacitor 12 connected in series, and the main winding 12 and the second AC switch 18 are connected in parallel.

Reference numeral 20 denotes an AC power supply for supplying a single-phase AC to the single-phase induction motor 10.

Reference numeral 22 denotes a circuit in which the AC power supply 20 and the main winding 12 and the auxiliary winding 14 are connected in parallel.
A first AC switch connected in series. This 1A
The C switch 22 also includes a bidirectional thyristor.

Reference numeral 24 denotes a first gate trigger circuit for sending a trigger to the gate of the first AC switch 22.

Reference numeral 26 denotes a first timer circuit for controlling the first gate trigger circuit 24.

Reference numeral 28 denotes a first setting circuit for controlling the timer setting of the first timer circuit 26.

Reference numeral 30 denotes a second gate trigger circuit for sending a trigger to the gate of the second AC switch 18.

Reference numeral 32 denotes a second timer circuit for controlling the second gate trigger circuit 30.

Reference numeral 34 denotes a second setting circuit for controlling the timer setting of the second timer circuit 32.

Reference numeral 36 denotes an input voltage detection circuit for detecting an input voltage from the AC power supply 20. The input voltage value detected by the input voltage circuit 36 is output to the first timer circuit 26 and the second timer circuit 32.

The first setting circuit 28 instructs at what point in the half cycle of the input voltage to turn on the first AC switch 22. The second setting circuit 34 also instructs at what point in the half cycle of the input voltage the second AC switch 18 should be turned on. Then, the second setting circuit 34
Is set as a precondition to instruct the second AC switch 18 to be turned on at the same time as the ON command of the first setting circuit 28 or thereafter. As a result, the second AC switch 18 does not turn on earlier than the first AC switch 22, so that the phase of the main winding current does not lead to the phase of the auxiliary winding current.

Under the above preconditions, the setting of the first setting circuit 28 and the second setting circuit 34 is performed so that the phase relationship between the main winding current and the auxiliary winding current is appropriately maintained. .

That is, when the rotation speed of the induction motor 10 is reduced, the timing at which the first AC switch 22 is turned on is delayed. The second AC switch 18 is turned on to maintain an appropriate phase relationship between the main winding current and the auxiliary winding current.
Delay the timing of the action. As a result, the main winding 1
2, the energizing time is shortened, and the value of the input is also reduced.

Even after the first AC switch 22 is turned off and the input is cut off, the energy stored in the main winding 12, the auxiliary winding 14 and the phase advance capacitor 16 keeps the second AC switch 18 on. , Can be regenerated. Thereby, the second AC switch 22 is turned on next.
The time required for the current to flow to the main winding 12 is
The current of the leading phase can continue to flow through the auxiliary winding. Therefore, a single-phase induction motor more efficient than the conventional induction motor 100 can be realized.

FIG. 2 is a timing diagram of the circuit diagram in FIG. 1, wherein IC indicates a common current, IA indicates an auxiliary winding current, and IM indicates a main winding current. Also, VM
Indicates the voltage between the main winding 112, VA indicates the voltage between the auxiliary winding 114 and the phase-advancing capacitor 116 connected in series, and VC indicates the voltage between the phase-advancing capacitor 116.

In the timing chart of FIG. 2, the first gate trigger circuit 24 outputs a trigger signal,
The C switch 22 is turned on / off. The second gate trigger circuit 30 outputs a trigger signal to the second AC switch 1.
8 to turn on / off the second AC switch 18. The first AC switch 22 and the second AC switch
The timing of turning on / off the switch 18 is shown in FIG.
As shown in the timing chart, the phases of the main winding current and the auxiliary winding current can be individually controlled in a state close to an ideal state by shifting the time.

As described above, in the present embodiment, the main winding 1
By separately controlling the phase of the input of the auxiliary winding 14 and the input of the auxiliary winding 14, the speed of the single-phase induction motor 10 can be controlled and the input power can be reduced.

The rotation speed of the single-phase induction motor 10 is
It may be detected by a control element or the like and fed back to the first setting circuit 28 and the second setting circuit 34, whereby a stable rotation speed may be constantly maintained.

[0031]

As described above, the second switch is switched to the first switch.
Main winding current
However, the phase does not advance beyond the auxiliary winding current.
Thus, the speed of the single-phase induction motor can be controlled, and the reduction of the input power can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

FIG. 2 is a timing chart in the circuit diagram of FIG. 1;

FIG. 3 is a circuit diagram of a conventional single-phase induction motor.

[Explanation of symbols]

 Reference Signs List 10 single-phase induction motor 12 main winding 14 auxiliary winding 16 advance capacitor 18 second AC switch 20 AC power supply 22 first AC switch 24 first gate trigger circuit 26 first timer circuit 28 first setting circuit 30 second gate trigger circuit 32 second timer circuit 34 second setting circuit 36 input voltage detection circuit

Claims (1)

(57) [Claims] In a single-phase induction motor in which a main winding is connected in parallel to an auxiliary winding and a phase-advancing capacitor connected in series, a current flowing from an AC power supply to the main winding and the auxiliary winding is turned on / off.
A first switch consisting of a bidirectional thyristor that is turned off, and only a current that is connected in series with the main winding and flows through the main winding is
It includes a second switch composed of bidirectional thyristors N / OFF, a first control means for controlling ON / OFF of the first switch, and a second control means for controlling ON / OFF of the second switch, the first (1) The control means includes a half cycle of an input voltage of the AC power supply.
Command to turn on the first switch at a given point in time
Are those out, the second control means, where in a half cycle of the input voltage
At a certain point, a command to turn on the second switch is issued.
And the command to turn it on is the first control
Issued at the same time as or after the command to turn on the means.
Single-phase induction motor, characterized in that to.