KR100689201B1 - Electronic starter for single phase induction motor - Google Patents

Abstract

The present invention relates to an electronic starting device for a single-phase induction motor that provides a more stable and reliable starting method than a mechanical starting method. The present invention relates to a main winding for driving an induction motor by receiving a current from a single-phase power source and a phase difference between the main winding. The auxiliary winding for generating the starting torque of the induction motor by the triac (triac) connected in series with the auxiliary winding for switching the current passing start of the auxiliary winding, and connected in parallel with the main winding (starting) A voltage supply unit which receives a voltage applied to the main winding during output and outputs a constant DC voltage, third and fourth capacitors C3 and C4 that charge the DC voltage output from the voltage supply unit, and the third and fourth A timer circuit for generating a trigger signal according to the charging voltages of capacitors C3 and C4, and a pulse of a trigger signal output from the timer circuit. It is only a conductive section consists of a photo-coupler to control a switching operation of the triac.

Accordingly, the present invention implements an electronic starting method using a low-cost timer IC and provides a starter having more reliability than a mechanical starting method by using a triac and a photo coupler as a means for connecting a power supply to an auxiliary winding. Can be.

Induction Motor / Starter / Auxiliary Winding

Description

Electronic starter for single phase induction motor

1 and 2 are perspective views showing a conventional mechanical starting device using a centrifugal force switch

3 is a circuit diagram showing an electronic starting device according to the present invention when the auxiliary winding is connected to the intermediate tap;

4 is a circuit diagram showing an electronic starting device according to the present invention when the auxiliary winding is directly connected to a single-phase power source;

5 is a diagram illustrating a detailed configuration of a timer circuit.

6 shows a detailed configuration of a photo coupler;

<Description of Symbols for Main Parts of Drawings>

10: voltage supply

C1, C2, C3, C4: first, second, third and fourth capacitors

D1, D2: first and second diodes

R1, R2, R3, R4, R5, R6: first, second, third, fourth, fifth and sixth resistors

ZD1: Zener Diode

20: timer circuit 22: first comparator

21: second comparator 23: flip-flop

30: photocoupler 40: triac

The present invention relates to a starting device for a single-phase induction motor, and more particularly to an electronic starting device that provides a more stable and reliable starting method compared to a mechanical starting method.

In general, since the single-phase induction motor has a normal torque and a reverse phase torque, that is, an alternating magnetic field is formed, the starting torque eventually becomes zero.

Therefore, a device for starting the two-phase induction motor at the start using the auxiliary winding for the initial start of the single-phase induction motor, and separating the auxiliary winding from the main winding when the start is completed.

In the starter of the single-phase induction motor according to the prior art, an auxiliary winding is connected to an intermediate tap (between the winding-1 and the winding-2) of the winding as shown in FIG. 1, and the auxiliary winding-2 and the auxiliary winding. Between the windings, a mechanical starting device using a centrifugal force switch and a starting capacitor is connected.

As shown in Fig. 2, the auxiliary winding is directly connected to the entire main winding, i.e., the single-phase power source, and a mechanical starting device using a centrifugal force switch and a starting capacitor is connected between the main winding and the auxiliary winding.

For example, when the voltage of the single phase power supply 220V is connected to the main winding, a voltage of 110V is applied to the auxiliary winding in FIG. 1, and a voltage of 220V is applied to the auxiliary winding in FIG. 2.

In such a mechanical starting device, the auxiliary winding should be designed to have a phase difference from the main winding in order to operate the single phase induction motor as a two phase induction motor at startup.

According to the conventional mechanical starting device, when the centrifugal force switch is turned on at the initial start of the induction motor, current flows in the auxiliary winding, and the motor is started by the phase difference between the main winding and the auxiliary winding.

Thereafter, when the motor reaches the normal speed and the centrifugal force switch is opened, when the power supply applied to the auxiliary winding is cut off, current flows to the main winding as a whole so that the motor rotates normally in a single phase.

However, in the conventional mechanical starter configured as described above, since the centrifugal force switch is turned on / off at a high voltage during start-up, sparks are generated in the switch, and as the operation is repeated, the reliability of the electric motor is deteriorated due to wear.

The present invention is to solve the above problems, the object of the present invention is to provide a more stable and reliable starting device for the initial start of the single-phase induction motor.

Another object of the present invention is to provide a starting device applying a new concept of electronic starting method.

Another object of the present invention is to provide an electronic starter that is easier to use and has a longer life than conventional mechanical starters.

In order to achieve the above object, the present invention provides a main winding for driving an induction motor by receiving a current from a single-phase power supply, an auxiliary winding for generating a starting torque of the induction motor by the phase difference with the main winding, the winding A voltage supply unit connected in parallel with the wire and receiving a voltage applied to the main winding at start-up to output a constant DC voltage (Vcc), and third and fourth capacitors (C3) charging the DC voltage (Vcc) output from the voltage supply unit. (C4), a timer circuit for generating a trigger signal according to the charging voltages of the third and fourth capacitors (C3) and (C4), and connecting the power to the auxiliary winding only at start-up, Single-phase transmission consisting of switching means for connecting the power of the auxiliary winding during the pulse period of the trigger signal output from the timer circuit to automatically disconnect the power of the winding. It provides an electronic starting device of the motor.

In addition, the present invention is connected to the main winding in parallel, the electronic starting device of the single-phase induction motor further comprises a voltage supply for receiving the voltage applied to the main winding and outputting the DC voltage (Vcc) required by the control circuit portion To provide.

Here, the voltage supply unit is connected to one end of the main winding, one end of the first capacitor (C1) to act as a resistance to the voltage applied to the main winding, one end is connected to the other end of the first capacitor (C1) and the other end is A first diode D1 connected to the other end of the main winding to provide a current path of the first capacitor C1, and configured at the other end of the first capacitor C1 to provide a predetermined level of AC power to the first capacitor C1. It is preferably composed of a second diode (D2) and a second capacitor (C2) for rectifying.

The control circuit unit charges the third and fourth capacitors C3 and C4 and the third and fourth capacitors C3 and C4 that charge the DC voltage Vcc output from the voltage supply unit. And a switching means for connecting the power supply to the auxiliary winding during the pulse period of the trigger signal output from the timer circuit.

The timer circuit compares the first comparator for comparing the charging voltage of the three capacitors C3 with the preset first reference voltage, and compares the charging voltage of the fourth capacitor C4 with the preset second reference voltage. A second comparator and an output of the first comparator as a set signal, and an output of the second comparator as a reset signal, and according to the input set signal and the reset signal. And a flip-flop for outputting a trigger signal having a pulse width of.

The switching means is connected in series with the auxiliary winding to triac for switching the start of current passing through the auxiliary winding, and is connected to an output terminal of the timer circuit, the triac according to the trigger signal output from the timer circuit. It is characterized by consisting of a photo coupler for controlling the on / off of the liquid.

Therefore, according to the present invention, it is possible to provide an electronic starting method capable of more stably performing the initial starting of the single-phase induction motor.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention that can specifically realize the above object will be described.

In the electronic starting device of the induction motor according to the present invention, Figure 3 shows a case of connecting the auxiliary winding to the middle tap, Figure 4 shows a case of connecting the auxiliary winding directly to the single-phase power source.

Here, the winding method (Fig. 3 or 4) of the winding can be selectively designed so that the maximum magnetic force is generated in the auxiliary winding according to the use of the induction motor.

In addition, by designing an appropriate auxiliary winding in consideration of the number of turns and the thickness of the winding, it is possible to adjust the starting torque of an appropriate size necessary for starting the motor.

3 and 4, the electronic starting device of the single-phase induction motor according to the present invention will be described.

In general, a starting device of a single phase induction motor is a main winding for driving an induction motor through a current applied from a single phase power source, and is connected in parallel with the main winding to generate starting torque of the induction motor by a phase difference from the main winding. It consists of auxiliary windings for

The present invention provides a control circuit unit for connecting a power supply to an auxiliary winding only at start-up to generate a starting torque of a single-phase induction motor, and automatically disconnecting the auxiliary winding from a power supply after a predetermined time; And a voltage supply unit 10 connected in parallel with the main winding to receive a voltage applied to the main winding when starting, and output a DC voltage (Vcc) required by the control circuit unit. There is this.

Here, the voltage supply unit 10 includes a circuit to which diodes D1 and D2, resistors R1, capacitors C1 and C2, and zener diodes ZD1 are applied.

In detail, the first capacitor C1 acts as a resistor for an input voltage as an AC capacitor, and the first diode D1 conducts only a forward current so that the AC power source of the first capacitor C1 can operate. Provide the path.

In addition, the second diode D2 and the second capacitor C2 rectify the input voltage, and are used to make a DC power supply having a predetermined level (for example, 5V to 10V) with respect to the single-phase power supply 220V.

Here, the second capacitor C2 is charged with a lower voltage because the first capacitor C1 limits the current flowing to the output terminal.

Subsequently, the constant voltage Vcc rectified through the second diode D2 and the second capacitor C2 is input to the control circuit through the first resistor R1 and the zener diode ZD1.

On the other hand, the control circuit unit is connected in series with the auxiliary winding triac (Triac) (40) for switching the start of the current passing through the auxiliary winding; Third and fourth capacitors C3 and C4 that charge the DC voltage Vcc output from the voltage supply unit 10; A timer circuit 20 generating a trigger signal according to the charging voltages of the third and fourth capacitors C3 and C4; And a photo coupler 30 that conducts only during the pulse period of the trigger signal output from the timer circuit 20 to control the switching operation of the triac 40.
In general, the triac 40 may malfunction due to an internal structure of the triac 40. However, the triac 40 may turn on by itself even when the current is suddenly increased or an external signal is not applied to the gate.
In order to prevent this, it is preferable to connect the resistor R7 for protecting the switching element and the capacitor C5 to the triac 40 in parallel.
In addition, in order to prevent the malfunction of the triac 40 and to ensure a more stable circuit from an inductive load, the resistance between the photocoupler 30 and the triac 40 may be reduced. It is preferable to connect R6 and R8).

The control circuit part of this structure aims at connecting a power supply to an auxiliary winding only for a predetermined time (for example, 2 kV-5 kV) at the time of initial starting.

First, the DC voltage Vcc output from the voltage supply unit 10 is charged through third and fourth capacitors C3 and C4 connected to the input terminal of the timer circuit 20.

In this case, it is preferable to set the capacitance of the fourth capacitor C4 to be 10 times or more larger than that of the third capacitor C3. As a result, the charging time of the fourth capacitor C4 is longer than that of the third capacitor C3.

In addition, as illustrated in FIG. 5, the timer circuit 20 includes a first comparator 22 for comparing the charging voltage of the three capacitors C3 with a preset first reference voltage, and the fourth capacitor ( The second comparator 21 for comparing the charging voltage of C4 and the preset second reference voltage and the output of the first comparator 22 are input as a set signal, and the second comparator 21 And a flip-flop for receiving an output as a reset signal and outputting a trigger signal having a predetermined pulse width according to the input set signal and the reset signal.

Here, the first reference voltage is connected to the non-inverting terminal (+) of the first comparator 22, and the second reference voltage is connected to the inverting terminal (-) of the second comparator 21.

At this time, in the timer circuit 20 itself, the first reference voltage is set to 1/3 of the DC voltage Vcc output from the voltage supply unit 10 (1/3 * Vcc), and the second reference voltage is DC It is configured by setting 2/3 of the voltage (Vcc) (2/3 * Vcc).

According to the configuration of the timer circuit 20, when the voltage is not charged to the third and fourth capacitors C3 and C4 at the initial startup, the charging voltage of the third capacitor C3 is the first reference. The first comparator 22 is a high signal (1) because it is less than the voltage (1/3 * Vcc) and the charging voltage of the fourth capacitor (C3) (C4) is less than the second reference voltage (2/3 * Vcc) And the second comparator 21 outputs the low signal 0, so that the output of the flip-flop 23 is set at a high level.

Subsequently, the third capacitor C3 is charged above the first reference voltage (1/3 * Vcc) and the fourth capacitor C4 is not yet charged to the second reference voltage (2/3 * Vcc). If not, the output of the first comparator 22 is changed to the low signal 0 while the second comparator 21 keeps the low signal 0 continuously.

That is, the low signal 0 is input to both the set terminal and the reset terminal of the flip-flop 23, so that the output of the flip-flop 23 is maintained in the previous state.

Meanwhile, while the charging voltage of the third capacitor C3 is continuously charged above the first reference voltage (1/3 * Vcc), the fourth capacitor C4 is the second reference voltage (2/3 * Vcc). When the above voltage is charged, the output of the second comparator 21 is changed to the high level (1) and the output of the first comparator 22 is kept at the low level (0), so the output of the flip-flop 23 is reset. (reset)

After the flip-flop 23 is reset, since the charging voltages of the third and fourth capacitors C3 and C4 are greater than the respective reference voltages, the output of the flip-flop 23 is continuously maintained.

Therefore, the condition for outputting the high level from the flip-flop 23 is that the charging voltage of the third capacitor C3 must be smaller than (1/3 * Vcc) and the charging voltage of the fourth capacitor C4 is increased. Should be less than (2/3 * Vcc).

By the operation of the timer circuit 20, a trigger signal having a predetermined pulse width is output to the output pin (3) of the timer circuit 20 at the initial startup, and the output does not come out after being charged.

Here, since the trigger signal pulse width of the timer circuit 20 is controlled by the time constant of the fourth capacitor C4 and the resistor R4 connected thereto, the trigger signal pulse width may be varied by adjusting the resistance value of the resistor R4.

In addition, the resistor R5 connected to the output pin (3) of the timer circuit 20 is used to adjust the magnitude of the input current of the photocoupler 30.

Here, the photocoupler 30 uses a triac driver as shown in FIG. 6, which is conducted only during the pulse period of the trigger signal output from the timer circuit 20, and is connected to the triac 40. Turn on).
Therefore, the triac 40 is turned on only while the output is output from the timer circuit 20 so that a current can flow in the auxiliary winding, so that the induction motor generates rotational force by the current having a phase difference between the main winding and the auxiliary winding. Done.

delete

The present invention is not limited to the above-described embodiments, and as can be seen in the appended claims, modifications can be made by those skilled in the art to which the invention pertains, and such modifications are within the scope of the present invention.

Referring to the effect of the electronic starting device of a single-phase induction motor according to the present invention described above are as follows.

First, by providing an electronic starting device using a low-cost timer IC can be used semi-permanently because the reliability is superior to the conventional mechanical starting method.

Second, by implementing a switching means applying a triac and photocoupler as a means for connecting the power supply to the auxiliary winding can be more secure initial start-up can improve the reliability of the product.

Claims (9)

Main winding for driving induction motor by receiving current from single phase power supply, An auxiliary winding for generating starting torque of the induction motor by a phase difference from the main winding; A voltage supply unit connected in parallel with the main winding and receiving a voltage applied to the main winding at start-up to output a constant DC voltage (Vcc); Third and fourth capacitors C3 and C4 for charging the DC voltage Vcc output from the voltage supply unit; A timer circuit for generating a trigger signal according to the charging voltages of the third and fourth capacitors C3 and C4; Switching means for connecting the power of the auxiliary winding during the pulse period of the trigger signal output from the timer circuit to connect the power to the auxiliary winding only at start-up and to automatically disconnect the power of the auxiliary winding after a certain time. Electronic starting device of a single-phase induction motor, characterized in that. delete The method of claim 1, The voltage supply unit A first capacitor C1 having one end connected to one end of the main winding and serving as a resistance to a voltage applied to the main winding; A first diode D1 having one end connected to the other end of the first capacitor C1 and the other end connected to the other end of the main winding, providing a current path of the first capacitor C1, Single phase induction, characterized in that it is composed of the second diode (D2) and the second capacitor (C2) for rectifying the AC power of the first capacitor (C1) to a predetermined level is configured at the other end of the first capacitor (C1). Electronic starting device of electric motor. delete The method of claim 1, The timer circuit A first comparator for comparing the charging voltage of the three capacitors C3 with a preset first reference voltage; A second comparator for comparing the charging voltage of the fourth capacitor C4 with a preset second reference voltage; Flip-flop for receiving the output of the first comparator as a set signal and the output of the second comparator as a reset signal and outputting a trigger signal according to the input set signal and the reset signal. An electronic starting device for a single-phase induction motor, comprising: a flip-flop. The method of claim 5, wherein The timer circuit Outputting a trigger signal having a predetermined pulse width under the condition that the charging voltage of the third capacitor C3 is smaller than the first reference voltage and the charging voltage of the fourth capacitor C4 is smaller than the second reference voltage. An electronic starting device for a single phase induction motor. The method of claim 6, The pulse width of the trigger signal output from the timer circuit is an electronic starting device of the single-phase induction motor, characterized in that the variable by adjusting the resistance value for determining the time constant of the fourth capacitor (C4). The method of claim 1, The switching means Triacs connected in series with the auxiliary windings for switching the current passing through the auxiliary windings; And a photo coupler connected to an output terminal of the timer circuit and configured to control on / off of the triac according to a trigger signal output from the timer circuit. Main winding for driving induction motor by receiving current from single phase power supply, An auxiliary winding for generating starting torque of the induction motor by a phase difference from the main winding; Triac connected to the auxiliary winding in series to switch the start of current passing through the auxiliary winding, A voltage supply unit connected in parallel with the main winding and receiving a voltage applied to the main winding at start-up to output a constant DC voltage; Third and fourth capacitors C3 and C4 for charging a DC voltage output from the voltage supply unit, A timer circuit for generating a trigger signal according to the charging voltages of the third and fourth capacitors C3 and C4, And a photo coupler configured to conduct the switching operation of the triac by conducting only during a pulse period of the trigger signal output from the timer circuit.

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