KR890004860Y1 - Starting-circuit of ac single-phase induction motor - Google Patents

Abstract

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Description

Starting circuit of AC single phase induction motor

The accompanying drawings are the starting circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

L1: Main coil L2: Starting coil

TC1: Triac TR1: Transistor

D1-D4: Diode VR1: Variable Resistor

R1-R4: Resistor C1-C5: Capacitor

The present invention relates to a starting circuit for starting an AC single-phase induction motor, and in particular, a simple circuit configuration, in which an AC single phase can be improved by applying power to the starting coil and driving the power supply to the starting coil to cut off the stability thereof. It relates to a starting circuit of an induction motor.

Conventionally, a contact type mechanical start switch operated by centrifugal force by rotation of an AC single-phase induction motor is used. However, this is often caused by contact wear of the switch and wear of the movable part, which frequently causes damage to the induction motor. Occurred.

Then, by installing a separate current transformer on a power line for applying AC power to the AC single-phase induction motor, detecting a starting current, conducting a triac with the detected starting current, and applying a power to the starting coil of the induction motor. There is also an automatic electronic relay for use, but this is because the secondary output voltage of the current transformer is weak and the capacity of the current transformer should be very large.In the normal operation, the starting automatic relay malfunctions due to abnormal current of the power supply, and power is supplied to the starting coil. And various defects.

The present invention, in view of such a conventional defect, by controlling the voltage charged to the capacitor to start the AC single-phase induction motor while applying power to the starter coil, and when the charge is completed to the capacitor by shutting off the power applied to the starter coil In addition to improving the stability of the circuit as well as to provide sufficient starting rotational power of the induction motor, it will be described in detail by the accompanying drawings as follows.

The accompanying drawings are starting circuit diagrams of the present invention, and as shown therein, one terminal a1 of the power plug PL is connected to one terminal terminal of the main coil L1 and one terminal terminal TC1 of the triac TC1. In addition, through the resistor (R1) and the capacitor (C1) connected in parallel to the connection point, the anode of the bridge diode (D1) and the diode (D3) of the gate of the triac (TC1) and diodes (D1-D4) Is connected to the cathode of the terminal, and is connected to the other terminal T2 of the triac TC1, the anode of the diode D2, and the cathode of the diode D4 through the capacitor C2 and the resistor R2 connected in series. In addition, the connection point is connected to the other terminal a2 of the power plug PL and the other terminal of the main coil L1 through the capacitor C3 and the starting coil L2, while the diode (D1) (D2) Is connected to the capacitor (C4), the variable resistor (VR1), the resistor (R3), and the capacitor (C5) connected in series, and the connection point is connected to the resistor (R4). The solution is connected to the emitter of the transistor TR1, the connection point of the resistor R3 and the variable resistor VR1 is connected to the base of the transistor TR1, and its collector is connected to the capacitors C4 and C5 and the diodes D3 and D4. Is connected to the anode.

Referring to the effect of the present invention configured in this way in detail as follows.

When AC power is applied to the power plug PL, the AC power passes through the resistor C1 and the capacitor C1, the starting coil L2 and the capacitor C3, and the rectified wave rectifies through the diodes D1-D4. After being smoothed by the capacitor C4, the capacitor C5 is charged through the variable resistor VR1 and the resistor R3. At this time, the low potential is applied to the base of the transistor TR1 at the initial charging time of the capacitor C5. It is on because it is applied.

Accordingly, in a state in which a positive AC power of one terminal al of the power plug PL is applied, the resistor R1 and the diode D1, the resistor R4, the transistor TR1, and the diode D4 are applied. When a constant current flows through the capacitor C3 and the starting coil L2, a constant voltage is applied to the gate of the triac TC1 so that it conducts. The cycle of the AC power is changed so that the other terminal a2 of the power plug PL is turned on. In the state where the positive AC power is applied to), the start coil L2, the capacitor C3, the diode D2, the resistor R4, the transistor TR1, the diode D3, and the resistor R1 are fixed. As the current flows, the triac TC1 is turned on by applying a constant voltage to the gate of the triac TC1. Thus, while the transistor TR1 is turned on, the triac TC1 continues to conduct so that the AC power applied to the power plug PL is turned on. Is applied to the starting coil L2 through the TC1 and the condenser C1, whereby the induction motor The.

In this case, when the charging time constant T of the capacitor C5 is T = (VR1 + R3) C5, the variable resistance VR1 is varied so that the time when the transistor TR1 is turned on is appropriately selected. AC power can be applied to the starting coil L2 for a period of time it can have.

When a predetermined time has elapsed and the induction motor has sufficient starting rotation power, and a constant voltage is charged in the capacitor C5 and a high potential is applied to the base of the transistor TR1, the transistor TR1 is turned off and the On the contrary, since there is no current flowing to the resistor R1, the voltage applied to one terminal T1 of the triac TC1 and its gate is the same, so that the triac TC1 is turned off, and thus the starting coil L2 of the induction motor. The AC power applied to the AC power is cut off, and the induction motor is continuously driven by the AC power applied to the main coil L1.

In addition, if the value of the magnetic term R1 is appropriately adjusted in the above, sufficient current can flow through the gate of the triac TC1, so that the starting rotational power of the induction motor can be increased, and the condenser C1 and C2 and the resistance ( R2) is for preventing malfunction due to surge voltage of AC power and voltage of triac TC1, and diode D5 is for protection according to on-off of transistor TR1.

As described above, the present invention can drive the induction motor by using the charging time constant of the condenser C5, and thus can cut off the AC power transferred to the starting winding L2 at an optimum time, thereby increasing the efficiency of the induction motor. As a result, the service life is long and, of course, high stability.

Claims (1)

In the starting circuit composed of the triac TC1 and the main coil L1, the starting coil L2, the capacitors C2 and C3, and the resistor R2, one terminal T1 of the triac TC1 is a resistor. (R1) and connected to its gate side via a capacitor (C1), and the connection point is formed together with the other terminal (T2) of the triac (TC1) to form an input terminal of the bridge diode (D1-D4), the bridge diode The output terminals of (D1-D4) are connected in parallel to the capacitor (C4), the variable resistor (VR1), the resistor (R3), and the capacitor (C5) connected in series, and the connection point of the capacitor (C4) and the variable resistor (VR1). The connection point of the variable resistor VR1 and the resistor R3 to the emitter side of the transistor TR1 is connected to the base side through the silver resistor R4, and the connection point of the capacitors C4 and C5 is connected to the collector side, respectively. Starting circuit of an AC single-phase induction motor, characterized in that configured.