KR200409268Y1 - Electronic starter for single phase induction motor - Google Patents

Abstract

The present invention is 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, and is connected in series with the auxiliary winding Triac for switching the start of current passing through the winding, a voltage supply unit connected in parallel with the main winding to receive a voltage applied to the main winding and outputting a constant DC voltage, using a DC voltage output from the voltage supply A starter circuit unit generating a trigger signal having a predetermined pulse width, a photo coupler conducting only during a pulse period of the trigger signal output from the starter circuit unit to control the switching operation of the triac, and being connected in parallel with the auxiliary winding Detects the voltage applied to both ends of the auxiliary winding due to the generation of counter electromotive force during the rotation of the motor It provides a voltage detector, the electromagnetic actuators of the single-phase induction motor constructed in accordance with the voltage across the secondary winding detected by the voltage detection section to output control signals for controlling the output of said start-up circuit for group.

Therefore, the present invention can provide a starting device having more reliability than a mechanical starting method by implementing an electronic starting method using a timer circuit, and induction motor by forcibly changing the power-on time of the auxiliary winding according to the rotational speed of the motor. There is an advantage that can shorten the startup time.

Induction motor / starter / auxiliary winding / start time

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 of a single-phase induction motor according to the present invention

4 shows a detailed configuration of a timer circuit;

<Description of the symbols for the main parts of the drawings>

10: voltage supply

C1, C2, C3, C4, C5, C6, C11: Capacitor

D1, D2, D11: Diode

R1, R2, R3, R4, R5, R6, R7, R8, R9, R23: Resistor

R11, R12, R21, R22: voltage divider

ZD1, ZD2: Zener Diode

20: starting circuit 21: second comparator

22: first comparator 23: flip-flop

30: photocoupler 40: triac

50: voltage detector

60: output control unit 61: voltage comparator

The present invention relates to a starting device of a single-phase induction motor, and more particularly to an electronic starting device that provides a more stable and reliable starting method than 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 using a new concept of electronic starting.

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.

Another object of the present invention is to provide an electronic starting device that can further shorten the starting time of a single-phase induction motor.

In order to achieve the above object, the present invention is 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 auxiliary Triac (Triac) for switching the start of the current passing through the auxiliary winding is connected in series with the winding, the voltage supply unit is connected in parallel with the main winding to receive a voltage applied to the main winding to output a constant DC voltage, the voltage supply A starter circuit part generating a trigger signal having a predetermined pulse width by using the output DC voltage, a photo coupler conducting only during a pulse period of the trigger signal output from the start circuit part, and controlling a switching operation of the triac, the auxiliary The auxiliary winding is connected in parallel with the windings due to the generation of counter electromotive force during the rotation of the induction motor. Provides an electronic starting device of the single-phase induction motor that is configured to output control signals for controlling the output of said start-up circuit according to the both-end voltage of the voltage detector, the secondary winding detected by the voltage detection section for detecting the voltage across the.

Here, the voltage supply unit; One end is connected to the power terminal of the main winding and the first capacitor (C1) that acts 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 connected to the ground terminal A first diode D1 providing a current path of the first capacitor C1, and a second diode configured at the other end of the first capacitor C1 to rectify the AC power of the first capacitor C1 to a predetermined level. It is preferable to consist of (D2) and the 2nd capacitor C2.

And, the starting circuit unit; Trigger having a predetermined pulse width according to the charging voltage of the third and fourth capacitors C3 and C4 and the third and fourth capacitors C3 and C4 outputting the DC voltage output from the voltage supply unit. And a timer circuit for outputting a signal and initializing the output of the trigger signal under the control of the output controller.

At this time, the timer circuit; A first comparator for comparing the charging voltage of the third capacitor 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; And a trigger having a predetermined pulse width according to the set signal and the reset signal by receiving the output of the first comparator as a set signal and the output of the second comparator as a reset signal. It is preferably configured as a flip-flop for outputting a signal.

In addition, 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, When the reset signal is applied from the output control unit in the pulse period of the trigger signal, the output of the trigger signal is forcibly reset.

And, the voltage detector; The first and second voltage divider resistors R11 and R12 connected to the auxiliary windings in parallel to divide and output the voltages of both ends of the auxiliary windings, and a diode D11 and a capacitor C11 are formed. The rectifier circuit may be configured to receive a voltage divided by the second voltage dividing resistors R11 and R12 to rectify the voltage to a predetermined level.

And, the output control unit; Third and fourth voltage divider resistors R21 and R22 connected in parallel with the power supply unit to divide and output a DC voltage output from a voltage supply unit, and from the third and fourth voltage divider resistors R21 and R22. It is preferable that the voltage divider output is a reference voltage, and the voltage across the auxiliary winding output from the voltage detector is an input voltage. The voltage comparator outputs a reset signal to the starting circuit unit when the voltage between the auxiliary winding is greater than the reference voltage. Do.

Therefore, according to the present invention, it is possible to provide an electronic starting method which can stably start the start-up of the single-phase induction motor and shorten the starting time by the rotational speed of the induction motor.

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

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 of the main winding.

In connecting auxiliary windings, the winding method can be selectively designed to produce the maximum magnetic force in the auxiliary windings depending on the intended 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.

Referring to Figure 3, when described the electronic starting device of a single-phase induction motor according to the present invention.

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 an electronic starting device using a triac to automatically control the supply and interruption of power for auxiliary windings.

To this end, the present invention is connected in series with the auxiliary winding and the triac 40 for switching the current passing start of the auxiliary winding, and one end is connected to the power terminal of the main winding and the other end is connected to the ground terminal to the main winding Start-up torque of the single-phase induction motor is generated by connecting the power supply to the voltage supply unit 10 that receives the applied voltage and outputs the DC voltage (Vcc) required by the starter circuit unit 20, and the auxiliary winding only at start-up. And a photocoupler for conducting switching of the triac by conducting only during a pulse period of the trigger signal output from the starter circuit unit 20 and the starter circuit unit 20 for automatically disconnecting the auxiliary winding from the power supply after a predetermined time. 30 and a voltage connected to the auxiliary winding in parallel to detect a voltage applied to both ends of the auxiliary winding due to generation of counter electromotive force during rotation of the induction motor. It is characterized by providing an electronic starting device comprising an output unit 50 and an output control unit 60 for controlling the signal output of the starting circuit unit 20 in accordance with the voltage across the auxiliary winding detected by the voltage detecting unit 50. .

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, the resistance between the photocoupler 30 and the triac 40 as shown in order to prevent the malfunction of the triac 40 and to ensure a more stable circuit from the inductive load. It is preferable to connect R6) and R8.

The voltage supply unit 10 includes a circuit in 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 an AC power source of the first capacitor C1 can be used. 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 110V.

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 starting circuit unit 20 through the first resistor R1 and the zener diode ZD1.

On the other hand, the starter circuit unit 20 includes third and fourth capacitors C3 and C4 that charge the DC voltage Vcc output from the voltage supply unit 10, and the third and fourth capacitors C3. And a timer circuit for generating a trigger signal in accordance with the charging voltage of (C4).

By such a configuration, the starting circuit unit 20 controls the start of the triac 40 to pass the current for a predetermined time (for example, 2 mA to 5 mA) at the time of initial startup, and connects the power supply to the auxiliary winding. It is done.

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

As shown in FIG. 4, the timer circuit 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 C4. The second comparator 21 for comparing the charging voltage with the preset second reference voltage and the output of the first comparator 22 are input as a set signal, and the output of the second comparator 21 is returned. And a flip-flop for receiving 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, the timer circuit has a first reference voltage is set to 1/3 of the DC voltage (Vcc) output from the voltage supply unit 10 (1/3 * Vcc), the second reference voltage is a DC voltage (Vcc) It is designed to be set to the size of 2/3 of (2/3 * Vcc).

According to the configuration of the timer circuit, the charging voltage of the third capacitor (C3) is the first reference voltage (1) in the state that the voltage is not charged to the third and fourth capacitor (C3) (C4) at the initial start-up Less than / 3 * Vcc) and the first comparator 22 outputs the high signal 1 because the charge voltage of the fourth capacitors C3 and C4 is less than the second reference voltage (2/3 * Vcc). Since the second comparator 21 outputs the low signal 0, 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). In this case, while the second comparator 21 keeps the low signal 0, the output of the first comparator 22 is changed to the low signal 0.

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).

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

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

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

Here, the photocoupler 30 is a triac driver, which conducts only during the pulse period of the trigger signal output from the timer circuit, thereby turning on the triac 40 connected to the auxiliary winding.

Accordingly, since the triac 40 is turned on only while the output is output from the timer circuit, the current flows in the auxiliary winding, and thus, the induction motor generates rotational force by a current having a phase difference between the main winding and the auxiliary winding.

On the other hand, the on period of the triac 40 is determined according to the trigger signal output from the timer circuit, the voltage detection unit 50 and the output controller 60 is the triac when the rotational speed of the induction motor rises to the normal range It is an object of the present invention to shorten the start time of the induction motor by forcibly changing the on-cycle of (40).

First, the voltage detectors 50 are connected in parallel with the auxiliary windings to divide the voltages of both ends of the auxiliary windings to divide and output the first and second voltage divider resistors R11 and R12, the diodes D11, and the capacitors C11. It is composed of a rectifier circuit for rectifying the voltage across the auxiliary winding output through the first and second voltage divider (R11) (R12) to a predetermined level of DC voltage.

In addition, the output controller 60 is connected to the voltage supply unit 10 in parallel to the third and fourth voltage divider (R21) (R22) for dividing and outputting the DC voltage output from the voltage supply unit, and the third And a voltage between both ends of the auxiliary winding and the reference voltage using the divided voltage output from the fourth voltage divider R21 and R22 as a reference voltage V_ref and the voltage between the auxiliary windings output from the voltage detector 50 as an input voltage. And a voltage comparator 61 for outputting the reset signal of the starting circuit unit 20 through the comparison of V_ref.

According to this configuration, since the first and second voltage divider resistors R11 and R12 of the voltage detector 50 are connected in series to each other and configured in parallel with respect to the auxiliary winding, the counter electromotive force is generated according to the speed of the induction motor after starting. The voltage between both ends of the variable auxiliary winding can be detected.

The voltage between both ends of the auxiliary winding output through the first and second voltage divider resistors R11 and R12 is output as a DC voltage through the diode D11 and the capacitor C11 and then as an input voltage of the output controller 60. Is approved.

Meanwhile, the third and fourth voltage divider resistors R21 and R22 of the output controller 60 are connected in series to each other so that the divided voltage for the DC voltage output from the voltage supply unit 10 is used as a reference for the voltage comparator 61. Provided by voltage V_ref.

At this time, the voltage comparator 61 receives the voltage across the auxiliary winding output from the voltage detector 50 through pin 3 (inverting terminal) and receives the third and third pins through pin 2 (non-inverting terminal). The reference voltage V_ref is input from the fourth voltage divider R21 and R22.

The voltage comparator 61 outputs a high level signal through pin 7 (i.e., output terminal) because the voltage across the auxiliary winding is lower than the reference voltage at the beginning of induction motor start, and then the rotation speed of the induction motor is If the voltage of both ends of the auxiliary winding becomes higher than the reference voltage as the speed increases, a low level signal is output.

In this case, when the high level signal is output from the voltage comparator 61, a high signal is applied to pin 4 (ie, a reset terminal) of the timer circuit to maintain the output of the trigger signal, and the low level signal is When output, a low signal is applied to the reset terminal of the timer circuit to initialize the output to force off the photocoupler 30 and the triac 40.

Therefore, the present invention maintains the on period of the triac 40 during the pulse section of the trigger signal output from the timer circuit, but the rotational speed of the induction motor increases within the pulse section of the trigger signal, so that the voltage across the auxiliary winding exceeds the reference voltage. When it increases, the start time of the induction motor can be shortened by forcibly turning off the triac 40 by initializing the timer circuit.

Not shown SC is a starting condenser connected in series with the auxiliary winding, RC is a running condenser connected to one side of the power terminal of the main winding.

In addition, reference numeral R0, which is not described, is a discharge resistor for discharging the voltage charged in the starting capacitor SC when the power supply of the auxiliary winding is disconnected after the start of the motor is connected to one side of the starting capacitor SC.

Similarly, when the power supply of the auxiliary winding is disconnected, R14 is a discharge resistor for discharging the voltage charged in the capacitor C11 of the voltage detector 50, and R9 is charged in the third capacitor C3 of the starting circuit unit 20. The discharge resistance for discharging the voltage.

The present invention is not limited to the above-described embodiments, and can be modified by those skilled in the art to which the present invention pertains as can be seen in the appended claims, and such modifications fall 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 circuit it can be used semi-permanently because the reliability is superior to the conventional mechanical starting method.

Second, by implementing a switching means using a triac and photocoupler as a means for connecting the power supply to the auxiliary winding, it is possible to safely perform the initial start-up can improve the reliability of the product.

Third, it is possible to reduce the power consumption of the product by reducing the starting time of the induction motor by forcibly changing the power supply time of the auxiliary winding in accordance with the rotational speed of the motor.

Claims (7)

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 to output a constant DC voltage; A starting circuit unit generating a trigger signal having a predetermined pulse width by using the DC voltage output from the voltage supply unit; A photo coupler conducting only during the pulse period of the trigger signal output from the starting circuit unit to control the triac switching operation; A voltage detector connected in parallel with the auxiliary winding to detect a voltage applied to both ends of the auxiliary winding due to generation of counter electromotive force when the induction motor is rotated; And an output control unit for controlling the signal output of the starting circuit unit in accordance with the voltage across the auxiliary winding detected by the voltage detecting unit. The method of claim 1, The voltage supply unit A first capacitor C1 having one end connected to a power supply terminal 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 ground terminal to provide 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. The method of claim 1, The starting circuit section Third and fourth capacitors C3 and C4 for charging the DC voltage output from the voltage supply unit; And a timer circuit for outputting a trigger signal having a predetermined pulse width according to the charging voltages of the third and fourth capacitors C3 and C4 and initializing the output of the trigger signal under the control of the output controller. Electronic starting device of a single-phase induction motor, characterized in that. The method of claim 3, wherein 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; A trigger signal having a predetermined pulse width according to the set signal and the reset signal by receiving the output of the first comparator as a set signal and the output of the second comparator as a reset signal; Electronic starting device of a single-phase induction motor, characterized in that consisting of a flip-flop (Flip-Flop) for outputting. The method of claim 4, 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, The electronic starting device of the single-phase induction motor, characterized in that forcibly reset the output of the trigger signal when a reset signal is applied from the output control unit in the pulse period of the trigger signal. The method of claim 1, The voltage detector First and second voltage divider resistors R11 and R12 connected in parallel to the auxiliary windings to divide and output voltages of both ends of the auxiliary windings; Comprising a diode (D11) and a capacitor (C11) of the single-phase induction motor, characterized in that the rectifier circuit is rectified to a predetermined level by receiving a voltage divided from the first and second voltage divider (R11) (R12) Electronic starter. The method of claim 1, The output control unit Third and fourth voltage divider resistors R21 and R22 connected in parallel with the power supply unit to divide and output a DC voltage output from the voltage supply unit; If the voltage across the auxiliary winding is greater than the reference voltage, the divided voltage output from the third and fourth voltage divider resistors R21 and R22 is the reference voltage and the voltage across the auxiliary winding output from the voltage detector is an input voltage. An electronic starting device for a single-phase induction motor, characterized by comprising a voltage comparator for outputting a reset signal to the starting circuit section.

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