KR860001240B1 - Induction motor - Google Patents

Abstract

The induction motor includes a field winding(4) connected to a voltage source(1) through a conduction control circuit(20) and a switch(3). A tertiary winding or a control winding(9) is electromagnetically coupled to the main winding(41). The control winding (9) and a capacitor(10) serve as an impedance for a closed loop. The conduction control circuit(20) is formed as a phase control circuit and comprises a triac(201). A series connection of a resistor(202) and a capacitor(203) is connected in parallel with the triac(201) for the purpose of preventing erroneous ignition or triggering of the triac (201).

Description

Induction motor

1 is a circuit diagram showing an example of an induction motor circuit including a conventional energization control circuit which is the background of the present invention.

2 is a voltage-current waveform diagram showing that harmonic distortion occurs in the conventional example of FIG.

3 is a voltage-current waveform diagram showing that the phase of current is delayed with respect to voltage in the conventional circuit of FIG.

4 is a circuit diagram showing another example of a conventional induction motor circuit.

5 is a circuit diagram showing an embodiment of the present invention.

6 is a voltage-current waveform diagram showing that harmonic distortion is eliminated and phase delay with respect to the voltage of the current is eliminated according to the fifth embodiment.

7 and 8 are vector diagrams for explaining the operation of the fifth embodiment.

7 is a conventional example of FIG.

8 is a fifth embodiment.

9 is a graph for explaining the effect of the embodiment of FIG. 5 (horizontal axis = frequency, vertical axis = integration of organic voltage).

FIG. 10 is a graph for explaining the effect of the embodiment of FIG. 5 (horizontal axis = rotational speed, vertical axis = noise level).

11 is a perspective view showing an example of the stator of the induction motor according to the fifth embodiment.

12 is a circuit diagram showing another embodiment of the present invention.

Fig. 13 is a circuit diagram showing another embodiment of the present invention.

14 is a circuit diagram showing another embodiment of the present invention.

FIG. 15 is a voltage-current waveform diagram for explaining the effect of the FIG. 14 embodiment.

* Explanation of symbols for main parts of the drawings

(1): AC power source (3): Switch

(4): field winding (5), (10): capacitor

(9): control winding (20): energization control circuit

(41): Sovereignty (42): Secondary winding

201: triac

The present invention relates generally to induction motors. More specifically, the present invention relates to an induction motor in which an effective voltage whose voltage is controlled through a phase control circuit or a chopper circuit in an AC power source is applied to the field winding.

FIG. 1 shows a circuit diagram which is a conventional example of such an induction motor. The AC power supply 1 is applied to the field winding 4 of the induction motor via the energization control circuit 2 and the switch 3. The winding winding 4 includes a main winding 41 and an auxiliary winding 42, and the capacitor 5 is connected in series to the auxiliary winding 42 again. Although not shown in the field winding 4, the rotor is installed in relation. In this way, the circuit shown in FIG. 1 constitutes a so-called condenser operation motor in which a starting torque is generated by the forward current flowing through the condenser 5, and the condenser is not disconnected even after starting. It is. The energization control circuit 2 includes a two-way conducting element (triac) with a control electrode as the switching element 21, and a trigger circuit (not shown) is connected to the gate of the triac 21. In addition, the triac 21 is connected in parallel with a series circuit of the resistor 22 and the condenser 23, and this series circuit is used to prevent a false arc or trigger miss of the triac 21. It is for. By turning on the switch 3, the relay winding 4 is applied with an alternating current voltage (indicated by the solid line V in FIG. 2) whose conduction phase is controlled by the energization control circuit 2. By changing the phase of the trigger pulse provided by the trigger circuit (not shown), the magnitude of the field flux and the rotational speed can be changed steplessly.

In the conventional induction motor circuit shown in FIG. 1, since the AC voltage is rapidly conducted by the energization control circuit 2, as shown by the solid line V in FIG. Wave distortion was occurring. The harmonic components included in this distorted waveform have a problem that vibration occurs in the motor or noise is generated from the motor. In addition, since the field winding 4 has an inductance component, the surge voltage at the time of inversion of the triac 21 is high, and therefore, a protective circuit is required, and as shown in FIG. The current I flowing through 4) caused a phase delay with respect to the applied voltage V, resulting in poor efficiency and power factor. That is, as shown in FIG. 3, the field current I is delayed with respect to the voltage V (= wt: w represents the angular frequency of the AC power source 1), which delays the power factor. It was causing.

Noise as described above is very problematic when such a motor is used as a driving source for a fan or similar fan. In other words, when the effective voltage applied to the field winding 4 is reduced by the energization control circuit 2 to decrease the rotational speed, the wind noise caused by the fan is naturally reduced, so that the noise caused by harmonic distortion is further disturbed. Will be.

4 is a circuit diagram showing another conventional induction motor circuit. The prior art example of FIG. 4 is described in, for example, Japanese Patent Laid-Open No. 44-18415, supplied on August 12, 1969, and is a tertiary winding or control winding electrically coupled to the field winding 4. (6) is installed and a tank circuit is comprised by this control winding 6 and the condenser 7. As shown in FIG. The variable resistor 8 is connected to the tank circuit in series or in parallel with the capacitor 7. By adjusting the resistance value of the variable resistor 8, the input current to the tank circuit can be controlled, whereby the speed control can be performed. Since the energizing control is not used in the conventional example shown in FIG. 4, no noise is generated due to harmonic distortion as in the prior art of FIG. 1. However, the crest value of the magnetic field flux is changed by controlling the input current to the tank circuit. As a result, the efficiency of the electric motor is deteriorated, and other problems occur such that a desired starting torque is not obtained in some cases. In addition, since the conventional example of FIG. 4 is not the speed control by the energization control, it is a matter of course that no consideration is given to the noise generated in the conventional example of FIG. 1, and the circuit shown in FIG. It is not applicable to the circuit shown in the figure. This is because in FIG. 4, the speed control is performed by the energization control circuit 2 in the circuit of FIG. 1 while the speed control is performed by the variable resistor 8.

It is therefore a main object of the present invention to provide an improved induction motor which can reduce noise generated as much as possible as an induction motor whose applied voltage is controlled by an energization control circuit.

The induction motor according to the present invention includes a field winding connected to an AC power source via an energization control circuit, a control winding electronically coupled to the field winding, and closed loop means for flowing an induction current through the control winding. .

According to the present invention, since the harmonic component generated due to the rapid conduction of the AC voltage by the energization control circuit can be greatly reduced, the noise generated in the motor can be effectively reduced.

In principle, the present invention can be applied to all induction motors. Therefore, the present invention can be used not only for a condenser operation motor but also for a condenser start type induction motor, an induction motor having a shading coil, or a split phase start type induction motor. The present invention can also be used not only for single-phase induction motors, but also for three-phase induction motors.

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

5 is a circuit diagram showing an embodiment of the present invention. The field winding 4 of the induction motor is connected to the AC power source 1 via the energization control circuit 20 and the switch 3. The field winding 4 includes a main winding 41 and an auxiliary winding 42, and a capacitor 5 is connected in series to the auxiliary winding 42. The tertiary winding 41 is electronically coupled to the tertiary winding to the control winding 9. The control winding 9 forms a closed loop together with the condenser 10 as an example of the impedance means.

The energization control circuit 20 is configured as a phase control circuit in this embodiment and includes a triac 201. In parallel with the triac 201, a series circuit of a resistor 202 and a condenser 203 for preventing erroneous arcing and trigger miss of the triac 201 is connected. In parallel with the AC power supply 1, the series circuits of the variable resistor 204, the resistor 205, and the capacitor 206 are connected, and the series connection contact between the resistor 205 and the capacitor 206 is two-terminal bidirectional. It is connected to the gate of the triac 201 via the negative resistance element (diac) 207.

The semi-fixed resistor 208 is connected to the variable resistor 204 in parallel. By changing the resistance of the variable resistor 204, the time to reach the minimum limit voltage of the diaak 207 changes. Therefore, the phase in which the firing pulse is applied to the gate of the triac 201 can be changed. In this manner, the conduction control circuit 20 controls the conduction phase of the AC voltage from the AC power supply 1, changes the effective value of the voltage applied to the field winding 4, and performs speed control of the induction motor. . The slide of the variable resistor 204 is interlocked with the switch 209, and when the slide of the variable resistor 204 is brought to a position where the resistance value is minimum, the switch 209 is turned on, and consequently the energization control circuit. (20) is substantially invalidated so that the induction motor runs at full speed.

As described above, when a voltage is applied to the field winding 4 through the energization control circuit 20, the rotor magnetic field is created by the current I _M flowing through the main winding 41 and the current I _A flowing through the auxiliary winding 42. An induced voltage is generated in the control winding 9. Since the control winding 9 forms a closed loop together with the condenser 10, the forward current flows through the control winding 9 by the induced voltage. Due to the induced induction current flowing through the control winding 9, the voltage-current characteristic at the time of conducting the triac 201 becomes as shown in FIG. 6, and the field winding 4 is connected to the AC power supply 1. As shown in FIG. It is a pure resistance load.

That is, the induction current flowing through the control winding 9 becomes a fast current by the capacitor 10 formed in the closed loop and the capacitive component formed by the winding 9, and the triac ( The voltage-current characteristic when 201) is conducted is as shown in FIG. 6, and the phase delay of the current is eliminated.

Thus, in the embodiment of FIG. 5, the phase delay with respect to the voltage of the current generated in the conventional circuit shown in FIG. 1 is eliminated, and as a result, the field winding 4 causes the forward resistance to the AC power supply 1 as a result. It becomes a load. This will be described in more detail with reference to the vector diagrams of FIGS. 7 and 8 below.

FIG. 7 is a vector diagram showing the relationship between voltage and current by the conventional circuit of FIG. 1, and FIG. 8 is a vector diagram showing the relationship between voltage and current according to FIG. When there is no closed loop (FIG. 5) including the conventional winding of FIG. 1, that is, the control winding 9, the current I _M flowing through the main winding 41 is delayed with respect to the voltage and the current flowing through the auxiliary winding 42. I _A becomes fast with respect to voltage. Therefore, the current I _T flowing through the entire field winding 4 is delayed with respect to the voltage as shown in FIG. As a result, the voltage-current characteristics are as shown in FIG. 3 as described above. On the other hand, according to the fifth embodiment, as a result of the interaction between the main winding 41 and the control winding 9, due to the capacitance component of the control winding 9 and the capacitance of the condenser 10, As the current I _M flowing through the main winding 41 proceeds as I _M shown in FIG. 8 by the forward current I _C flowing through the control winding 9, this current I _M and the auxiliary winding 52 As a result, the synthesized current I _T with the current I _A flowing through becomes the same as the voltage V as shown in FIG. As a result, the voltage V applied to the field winding 4 and the synthesized current I flowing therein become the same phase. As a result, the voltage-current characteristics are as shown in FIG.

In addition, the case in which the control winding 9 is electronically coupled to the main winding 41 has been described. However, the control winding 9 may be electronically coupled to the auxiliary winding 42 or throughout the main, beam and both windings. That is, the field winding and the control winding may be electronically combined.

In addition, the impedance means for forming the closed loop together with the control winding 9 may be a capacitor as shown in the fifth embodiment, but according to the experiments of the present inventors, the capacitance component is added to the control winding 9. It is pointed out in advance that as long as it exists, it is confirmed that both ends of the control winding 9 may be directly connected or may be connected via a resistance component.

On the other hand, the vibration of the field of the induction motor is caused by the distortion of the magnetic flux generated therein. Therefore, the present inventors confirmed that the closed loop of the present invention reduces the waveform distortion of the magnetic flux causing the noise by performing frequency analysis on the integral waveform of the induced voltage (magnetic flux waveform) by the field winding 4). The results are shown in FIG. In FIG. 9, the solid line A shows the case where there is no closed loop like the first circuit, and the dotted line B shows the case of the FIG. In addition, in FIG. 9, it is pointed out beforehand that the dashed-dotted line C shows the result of the following FIG. 12 Example. As can be seen from FIG. 9, according to the fifth embodiment, the harmonic distortion component of the magnetic flux waveform is reduced. This is inferred to be due to the following reasons, in addition to eliminating the phase delay of the current described above. That is, in general, when the phase control is performed by the energization control circuit 20, the excitation current to the field winding 4, i.e., the magnetomotive force is interrupted, so that a large harmonic component is included, but it flows through the closed loop of the present invention. It is considered that the current flows in a phase different from that of the main winding 41 (field winding 4), thereby supplementing the blank of the field magnetic force.

As described above, the harmonic content of the field magnetic flux is reduced, so that the noise from the motor which has occurred conventionally can be greatly reduced as shown in FIG. In FIG. 10, the solid line D shows the right diameter of the conventional circuit of FIG. 1, and the dotted line E shows the case of the FIG. 5 embodiment. In addition, in FIG. 10, the dashed-dotted line D 'shows the result of measuring by changing the wire diameter etc. of the field winding in the conventional circuit of FIG. As is apparent from FIG. 10, especially when the rotation speed is low, the effect of improving the noise by the closed loop according to the present invention is remarkable. That is, the improvement of about 8dB in the minimum rotational area was seen. The noise reduction effect in such a low speed region is particularly effective when an induction motor is used in a fan or a ceiling fan.

11 is a perspective view showing an example of a stator having a control winding according to the present invention. The stator core 100 is formed by stacking a plurality of iron core plates 10. In the stator core 100, a predetermined number of first slots 102a and second slots 102b each having a radial distance from the peripheral end portion thereof are formed in a reel shape at a peripheral edge thereof. The stator core 100 has a central hole in which the metal pipe 103 is press-fitted and fixed, and a plurality of ventilation holes 104 therein. An insulating film is formed on each slot inner wall of the stator core 100, and an insulating film is formed on the end surface of the iron core 100 in the same manner. The main winding 41 and the auxiliary winding 42 are wound in the slots 102a and 102b, respectively. The control winding 9 is wound in the same slot 102a when the winding winding 41 is wound. Thus, when the main winding 41 and the control winding 9 are wound in the same slot, there is an advantage that the manufacturing process can be simplified.

In addition, although the closed loop according to the present invention can reduce the harmonic components of the magnetic flux waveform and thereby increase the noise reduction effect, the closed loop additionally brings about an improvement in efficiency and power factor. . This is because the phase delay with respect to the voltage V of the current I _T as shown in FIG. 6 and FIG. 8 is improved. The present inventors confirmed that the efficiency and power factor of the closed loop is improved according to the impedance of the constituting impedance means, that is, the capacity of the condenser 10 (FIG. 5), as shown in the following table.

In the experiment, a fan connected as a load to a 20-pole condenser operation motor having the following ratings was used.

Winding method: main winding 0.28ø; 145T × 20

Auxiliary winding 0.25 °; 185T × 20

Control winding 0.28 °; 145T × 20

Capacitor (5): 4.0 μF

Capacitor (10): 4.0, 8.0, 12μF

Voltage: 120V

Frequency: 60HZ

[table]

In the above table, when the closed loop including the control windings 9 is installed, the power factor and the efficiency are improved, and the power factor can be set to 1 while the capacity of the capacitor 10 is appropriately selected.

12 is a circuit diagram showing another embodiment of the present invention. This embodiment differs from the fifth embodiment in that the resistor 11 is used instead of the capacitor as an impedance means for cooperating with the control winding 9 to form a closed loop.

When the impedance means constituting the closed loop is approximately zero, that is, even when both ends of the control winding 9 are directly continuous, it is confirmed by the experiments of the present inventors that, as in the fifth embodiment, it has a noise reduction effect. It is becoming. This is because the harmonic components of the magnetic flux waveform can be effectively removed by the capacitive components accompanying the control winding 9.

In the twelfth embodiment, the resistance 11 is inserted as an impedance means, and heat generation by the control winding 9 is prevented. As described above, when the impedance of the impedance means is set to approximately 0, since the wire diameter of the control winding or the field winding cannot be too thick in relation to the drop of the slot, the winding resistance is increased, resulting in heat generation. There is a thing. On the other hand, in the twelfth embodiment of the present invention, the resistor 11 is inserted, the heat is generated by the resistor 11, and the heat generated by the control winding 9 is reduced. In this way, when the resistor 11 is used as the impedance means for forming the closed loop together with the control winding 9, the noise generated from the motor can be further reduced. By using the resistor 11, as indicated by the dashed-dotted line C in FIG. 9, harmonic distortion of the magnetic flux waveform can be further reduced, and noise is thus significantly reduced.

13 is a circuit diagram showing another embodiment of the present invention. This embodiment is an embodiment in which the closed loop of the present invention is applied to a so-called seating coil induction motor. That is, the shading coil 12 is installed in relation to the field winding 4, and the shading coil 12 generates a starting torque. A control winding 9 is electronically coupled to the field winding 4, and the control winding 9 forms a closed loop in cooperation with an impedance method such as a condenser 10. Also in this FIG. 13 Example, the experiment confirmed that the noise reduction effect similar to FIG. 5 or 12 Example is improved.

14 is a circuit diagram showing another embodiment of the present invention. This embodiment differs from the energization control circuit 20 in which the energization control circuit 20 'is the foregoing embodiment. The energization control circuit 20 'includes a bridge rectifier circuit 211 and a transistor 212 connected to the rectifier circuit 211. Control pulses from a pulse circuit (not shown) are applied between the base emitters of the transistors 21. Then, this control pulse changes the execution voltage applied to the field winding 4 as shown in FIG. 15 by changing the time period t ₁ of the high level and the time period t ₂ -t ₁ of the low level. Thus, the rotational speed of the induction motor can be controlled thereby.

을 높게 설정할 수가 있고 통전제어회로(20')의 제어주파수에 수반하는 진동소음까지도 귀에 거술리는 주파수이상으로 할 수가 있다.Also in this FIG. 14 embodiment, by the action of the closed loop including the control winding 9, the delay of the current I with respect to the voltage V can be improved, and the generation of harmonics can be prevented, thereby reducing noise. Can be reduced. In addition, since the rise of the current becomes the same as the voltage waveform, vibration noise

Can be set high, and even the vibration noise accompanying the control frequency of the energization control circuit 20 'can be made higher than the frequency of the ear.

In the above embodiment, the so-called condenser operation motor and the shading coil induction motor have been described. However, the present invention can be applied to various induction motors, such as condenser starting type induction motors and divided phase starting type induction motors.

The present invention is applicable not only to single-phase induction motors, but also to multiphase (three-phase) induction motors.

Claims (13)

A closed loop that forms a closed loop in cooperation with the control winding so as to generate an induced current in the field winding connected to an AC power source through an energization control means, a control winding electronically coupled to the field winding, and the control winding. Induction motor, characterized in that consisting of means. The induction motor according to claim 1, wherein said energization control means includes means for changing the effective voltage applied to said field winding by repeating conduction / disconnection of said AC power supply. The induction motor according to claim 2, wherein the energization control means includes means for changing a conduction phase of the AC power supply. The induction motor according to claim 2, wherein the energization control means includes a chopper means for cutting the AC power and applying it to the field winding. The induction motor according to claim 1, wherein the closed loop means includes impedance means for interposing a predetermined impedance in the current path of the closed loop. 6. An induction motor as claimed in claim 5, wherein said impedance means comprises a condenser means. The induction motor as claimed in claim 5, wherein the impedance means includes resistance means. The induction motor according to claim 5, wherein the impedance means has an impedance of substantially zero. The induction motor according to any one of claims 1 to 8, wherein the field winding includes a main winding and an auxiliary winding connected in parallel to the main winding. The induction motor according to claim 9, further comprising a capacitor connected in series with said auxiliary winding. The induction motor according to any one of claims 1 to 8, wherein a shading coil is installed in relation to the field winding. 9. The stator of claim 1, comprising a stator, the stator including a plurality of slots for winding the field windings into each of which the control winding is any of the plurality of slots. Or each of the induction motors, which is accommodated together with the field windings. The field winding according to claim 12, wherein the field winding includes a main winding and an auxiliary winding connected in parallel to the main winding, and the control winding is accommodated with any one of the plurality of slots or with each of the main windings. Induction motor.

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