KR0127193Y1 - Improved starting circuit of single phase induction motor - Google Patents

Abstract

The present invention relates to a maneuverability improvement circuit of a single-phase induction motor.

The present invention, in the electric circuit of the single-phase induction motor comprising a main winding forming a main magnetic field and a starting winding forming a rotating magnetic field with respect to the magnetic field generated by the main winding, the winding in the direction opposite to the winding direction of the main winding A distinctive feature is that a separate circuit section in which the activated starting winding and the auxiliary PTC relay are connected in series is connected in parallel with a part of the main winding.

Therefore, since the magnetic field by the starting auxiliary winding is added at the time of initial motor starting, the starting torque larger than the starting torque by the conventional main winding and the starting winding can be obtained.

Description

Maneuverability Improvement Circuit for Single-Phase Induction Motors

1 is a schematic electrical circuit diagram of an example of a conventional single-phase induction motor.

2 is a characteristic curve showing the temperature-resistance characteristics of the PTC relay.

3 is a characteristic curve diagram showing RPM-torque characteristics of a conventional single-phase induction motor.

Figure 4 is a schematic diagram of the electrical circuit of the maneuverability improvement circuit of the single-phase induction motor according to the present invention.

5 is an equivalent circuit diagram of a main winding of a conventional single-phase induction motor equivalently displayed according to a circuit analysis.

6 is an equivalent circuit diagram of the main winding in the maneuverability improvement circuit of the single-phase induction motor according to the present invention equivalently displayed according to the circuit analysis.

7 is an equivalent circuit diagram equivalently displayed according to the operating characteristics of a conventional single-phase induction motor.

8 is an RPM-torque characteristic curve diagram of a motor employing a driving force improvement circuit of a single-phase induction motor according to the present invention.

* Explanation of symbols for main parts of the drawings

10,20: Squirrel rotor 11,21: Sovereign

12,22: MW winding 13,23: PTC relay

24: starting auxiliary winding 25: starting auxiliary PTC relay

The present invention relates to a circuit for improving the maneuverability of a single phase induction motor. In particular, the maneuvering power of a single phase induction motor provides a large output at start-up and a relatively small output at start-up to enable efficient operation as a whole. Relates to an improvement circuit.

In general, home refrigerators, commercial show window cases, various vending machines and the like are equipped with a predetermined refrigeration / refrigeration system for the purpose of refrigeration / refrigeration. A mechanism for compressing and circulating refrigerant gas as one of such refrigeration / refrigeration systems is commonly employed. For this purpose, a pipe facility and a compressor for refrigerant gas circulation are used. And, an electric motor is usually installed to drive such a compressor. In particular, single-phase induction motors are usually used for home refrigerators.

1 of the accompanying drawings is a schematic electrical circuit diagram of an example of such a conventional single-phase induction motor.

Referring to this, the conventional single-phase induction motor is a main winding 11, which is a driving winding that provides a driving force for rotating the squirrel rotor 10 by forming a main magnetic field, and generates a predetermined auxiliary magnetic field sovereignty A starting winding 12, which is an auxiliary winding that enables initial starting of the cage rotor 10 by forming a rotating magnetic field with respect to the magnetic field generated by the line 11, is connected in parallel, and the starting winding 12 As shown, a PTC relay (Positive Thermal Coefficient relay) 13 is connected in series.

On the other hand, as shown in FIG. 2, the PTC relay 13 has a low resistance value when no current flows, and at the time of initial energization, a large current as indicated by the dotted line 15 is generated in the starting winding 12 and The PTC relay 13 may flow to a circuit portion formed by serial connection. However, when electricity is supplied for a predetermined time, as the temperature of the PTC relay 13 increases, the resistance of the PTC relay 13 is increased to indicate the solid line 16. As can be seen, the resistance reaches a high resistance level of 10 ⁵ -10 ⁶ [kV], and as a result, almost no current flows to the circuit portion formed by series connection of the starting winding 12 and the PTC relay 13.

The conventional single-phase induction motor employing the PTC relay 13 having such characteristics has a main winding 11 and a parallel lightning rod section (starting winding 12 + PTC relay 13) at the initial stage of starting as shown in FIG. )], So it is rotated by the characteristic that torque is output at 'zero' RPM as indicated by dotted line 17. Then, after a predetermined time has elapsed, the resistance of the PTC relay 13 is increased to a high value, thereby driving along the torque characteristic curve of only the main winding 11, which is the driving winding, as indicated by the solid line 18. In connection with these characteristic curves, it can be seen that the torque of the motor must be greater than the force of the load indicated by the dashed line 19 in order for the motor to be started and operated.

On the other hand, the hermetic reciprocating compressor, which is frequently used in refrigerators and the like, has a very large starting load, and therefore, the motor used therein requires a particularly large torque. In order to meet such demands, there is a method of increasing the output of the motor, but in this case, it is pointed out that the increase in power consumption and the winding temperature of the motor are increased due to the increase in no-load loss during operation.

The present invention has been devised in view of the above problems, and it is possible to obtain a good starting characteristic even under low voltage by increasing the output at start-up, and to reduce the output when the start-up is completed and become a normal operation state. It is an object of the present invention to provide a circuit for improving the maneuverability of a single-phase induction motor.

In order to achieve the above object, the driving force improvement circuit of the single-phase induction motor according to the present invention includes a main winding for forming a main magnetic field and a starting winding for forming a rotating magnetic field with respect to the magnetic field generated by the main winding. In the electric circuit of the single-phase induction motor, a distinctive circuit is characterized in that a separate circuit portion in which the starting auxiliary winding wound in the direction opposite to the winding direction of the main winding and the auxiliary PTC relay are connected in parallel with a part of the main winding. have.

In this way, a separate circuit portion consisting of the serial connection of the starting auxiliary winding and the auxiliary PTC relay is connected in parallel with a part of the main winding which is the driving winding, and is added to the magnetic field by the starting auxiliary winding at the initial startup. Starting torque can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a schematic diagram of the electric circuit of the driving force improvement circuit of the single-phase induction motor according to the present invention.

Referring to this, the maneuverability improvement circuit of the single-phase induction motor according to the present invention is provided with a main winding 21, which is a driving winding that provides a driving force for rotating the cage rotor 20 by forming a main magnetic field, The starting winding 22, which is an auxiliary winding that enables the initial starting of the cage rotor 20 by generating a magnetic field to form a rotating magnetic field with respect to the magnetic field generated by the main winding 21, is the main winding 21. It is wound in a direction opposite to the winding direction of and is connected in parallel with the main winding (21). Then, the PTC relay 23 is connected in series to the start winding 22. In addition, one end portion of one branch circuit portion including a separate starting auxiliary winding 24 and an auxiliary PTC relay 25 connected in series is connected to a predetermined point P of the main winding 21. Therefore, the branch circuit portion which consists of the lower half (on drawing) of the main winding 21 and the starting auxiliary winding 24 and the auxiliary PTC relay 25 connected in series with respect to the said predetermined point P is mutually parallel connection circuit. Will be configured.

Then, the torque characteristics related to the operation of the motor when the driving force improvement circuit of the single-phase induction motor according to the present invention as described above is employed in the motor will be described.

When the circuits of the main windings 11 and 22 which are the driving windings are analyzed in FIGS. 1 and 4, it can be interpreted as a combination of the resistance R and the inductive reactance (X) component.

That is, the circuit of the main winding 11 in FIG. 1 may be represented by a series connection circuit of the resistor R _B and the inductive reactance X _B as shown in FIG. 5. If the inductive reactance X _B is assumed to be X _B1 + X _B2 , then the impedance at that time is Z _B ,

It is represented by

On the other hand, in Fig. 4, the circuits of the starting auxiliary winding 24 and the auxiliary PTC relay 25 of the branch circuit portion constituting the parallel winding with the main winding 21 and a part of the main winding 21 are shown in Fig. 6. Can be represented as This is the result of the parallel insertion of a maneuverability improvement auxiliary winding consisting of another resistance R _P and an inductive reactance X _B2 into a main winding composed of the resistance R _B and the inductive reactance X _B of FIG. 1. Here, in particular, the winding direction of the auxiliary winding 24 for improving maneuverability is opposite to the winding direction of the main winding 21 so that the reactance component is -jX _B2 . This is for the magnetic force line generated by the main winding 21 and the magnetic force line generated by the starting auxiliary winding 24 not to be canceled but summed together so that the magnetic force lines are augmented as a whole. At this time, R _P is obtained by adding the resistance R _PTC of the auxiliary PTC relay 25 for improving mobility to the pure resistance component R _B2 of the auxiliary winding 24 for improving mobility. Here, assuming that R _P = R _n for ease of calculation, and the composite impedance in the dotted line display of FIG. 6 is Z _B '',

It is represented by Therefore, if the total impedance in the circuit shown in Fig. 6 is Z _B ',

It is represented by

On the other hand, since the resistance R _B in FIG. 5 can be seen as R _B = R _m + R _n , Equation (2) is as follows.

Therefore, the resistance of the equation (1) of the impedance Z _B and 3, the impedance Z _B 0, i.e., Z _B Z _B the auxiliary winding (24), improve maneuverability so as to be the "Z _B -Z in _B 'of If the over reactance is selected, the total impedance at the time of insertion of the auxiliary winding for improving maneuverability is reduced compared to the conventional method of FIG. As the impedance decreases, the current flowing in the winding is relatively increased, and the torque is approximately proportional to the square of the current, so that the torque can be increased by lowering the impedance.

On the other hand, the maximum torque Tmax of the residual motor can be expressed as follows when the motor is shown by an equivalent circuit composed of primary and secondary resistance and reactance components as shown in FIG.

In this equation (4), r ₂ and x ₂ are the resistance and reactance values of the rotor on the secondary side induced by the magnetic lines generated by the primary winding, so they are proportional to r ₁ and x ₁ of the primary winding. , R ₁ and x ₁ can be seen as R and X in FIGS. 5 and 6. Therefore, the above-mentioned (4) where r and x is the smaller, so increase the maximum torque (Tmax), the smaller the impedance Z _B 'in the designed than the impedance Z _B of the conventional method if the applied voltage V is constant. Accordingly, the starting characteristic is improved.

However, if the operation is continued in the Z _B 'state, the operation is continued with a torque larger than the torque required for operation, so the no-load loss is increased, thereby increasing the power consumption, and in some cases, the winding temperature is increased. There is a possibility that a situation such as a short circuit between lines due to the insulation layer breakdown, or even burnout of the coil may occur. In order to prevent this, in the present invention, the auxiliary PTC relay 25 is connected in series to the starting auxiliary winding 24 (see FIG. 4). As a result, during start-up, a current flows normally in the circuit section including the auxiliary winding 24 and the auxiliary PTC relay 25. After the startup is completed, the resistance of the auxiliary PTC relay 25 rises as described in FIG. As a result, almost no current flows through the circuit portion formed of the auxiliary winding 24 and the auxiliary PTC relay 25. Accordingly, the motor is operated with the required torque only by the sovereign winding, which leads to a reduction in power consumption.

On the other hand, Figure 8 is a torque characteristic curve showing the torque characteristics from starting to normal operation in the motor employing the driving force improvement circuit of the single-phase induction motor according to the present invention.

Referring to this, reference numerals 17 and 18 show torque characteristics in a conventional single-phase induction motor as described in FIG. 3, and 17 denotes a drive circuit in which a main winding, which is a driving winding, and a parallel circuit (starting winding + PTC relay) are operated. The torque characteristic of the city is shown, and 18 is the torque characteristic of the operation by the main winding only. Reference numerals 27 and 28 denote torque characteristics of the motor employing the driving force improvement circuit of the single-phase induction motor according to the present invention, and reference numeral 27 denotes the main winding 21, the starting winding 22, and the PTC in FIG. Torque characteristics during start-up and operation by the relay 23, the auxiliary winding 24, and the auxiliary PTC relay 25 are shown, and 28 is the torque characteristic during starting and operation by only the main winding 21 as the driving winding. It is to show off. Here, reference numeral 19 denotes a load.

As can be seen from the above torque characteristic curve, it can be seen that the starting torque of the motor when the starting force improvement circuit of the single-phase induction motor of the present invention is adopted is further increased than the starting torque of the conventional single-phase induction motor.

As described above, the driving force improvement circuit of the single-phase induction motor according to the present invention is connected to a part of the main winding, which is the driving winding, by a separate circuit part consisting of a serial connection of the starting auxiliary winding and the auxiliary PTC relay, Since the magnetic field by the starting auxiliary winding is added, it is possible to obtain a starting torque larger than the starting torques of the conventional main winding and the starting winding.

Claims (1)

In an electric circuit of a single-phase induction motor having a main winding forming a main magnetic field and a starting winding forming a rotating magnetic field with respect to the magnetic field generated by the main winding, the starting auxiliary winding wound in a direction opposite to the winding direction of the main winding. A separate circuit portion in which a winding and an auxiliary PTC relay are connected in series is connected in parallel with a part of the main winding.