KR100817575B1 - Electronic circuit for starting a single phase induction motor - Google Patents

Abstract

An electronic circuit for operating a single-phase induction motor of a type operating in association with an AC power source F, having at least one driving coil B1 and one starting coil B2, comprising a rotor and a stator, A trigger electronic switch, a trigger circuit TR of the trigger electronic switch, and a blocking circuit BL for controlling a trigger pulse of the trigger electronic switch, wherein the blocking circuit BL is driven by a rotation of the rotor. An electronic circuit for starting a single-phase induction motor that maintains its blocking state while there is an induced voltage in the coils of (M) to maintain the blocking state for a predetermined time after the induced voltage is reduced.

Single phase induction motor, AC current power supply, driving coil, starting coil, trigger electronic switch, trigger circuit, blocking circuit

Description

Electronic circuit for starting a single phase induction motor

The present invention relates to an electronic circuit for starting a single phase induction motor, and more particularly, to an electronic circuit for starting an induction motor having electronic circuits with a starting electronic switch.

Single phase induction motors are widely used for their simplicity, strength and high performance. Such motors are used in some industrial applications, as well as in home electrical appliances such as refrigerators, freezers, air conditioners, hermetic compressors, washing machines, pumps, and fans.

Typically, such single-phase induction motors are provided with a cage-type rotor and a coil stator having two windings, a running coil and a starting coil.

During normal operation, when an alternating voltage is supplied to the driving coil and temporarily supplied to the starting coil at the start of operation, a rotating magnetic field is generated in the air gap of the stator, accelerating the rotor and starting the engine. The conditions necessary to promote it are provided.

Such a rotating magnetic field can be obtained by supplying the starting coil with a current displaced in time with respect to the current flowing in the driving coil, preferably at an angle close to 90 degrees.

This temporal displacement between the currents flowing in both coils is achieved by installing an external impedance by the structural feature of the coils, or in series with one of these coils, typically in series with the starting coil. Typically, the value of the current flowing in the starting coil during the starting operation of the motor is high, and it is necessary to use a switch to cut off this current after a time required to promote the acceleration of the motor.

In a motor requiring high efficiency, the starting coil is not completely disconnected at the completion of the starting period. A capacitor, i.e. a running capacitor, is maintained in series with the starting coil, providing sufficient current to increase the maximum torque of the motor and its efficiency.

For motors of such a configuration, in which permanent impedance is provided in series with the starting coil during normal operation of the motor, several starting devices of PTC or electronic type are known, as described in US Pat. No. 5,051,681. As described in Brazilian patent PI201210, a known prior art starting circuit using PTC as the starting device has some drawbacks such as high energy consumption.

As described in US Pat. No. 5,051,681, a starter circuit having an electronic starter generally employing a triac does not have the same energy consumption problem as a circuit using PTC, but has a drawback that is susceptible to voltage fluctuations. In addition, when a voltage transient occurs or a predetermined state in which the power supply to the motor is cut off, the circuit is energized so as to restart the motor regardless of the power supply state of the motor at that time. The drawback is that current overload occurs and overheating of certain components occurs.

It is a general object of the present invention to avoid damage to motor components due to excessive voltage overload due to transients, disturbances and interruptions of power supply caused by the power source of the motor, without changing the energy consumption conditions of the motor. To provide a simple structure and low-cost single-phase induction motor starting electronic circuit.

Another object of the present invention is to provide a starting circuit as described above, which can be used with an operating (or permanent) capacitor or other impedance installed in series in the starting coil of the motor.

It is still another object of the present invention to provide a circuit as described above having a structure which enables the use of two connection terminals.

The objectives are: an electronic circuit for starting a single phase induction motor of a type, operating in association with an alternating current power source, having at least one driving coil and one starting coil, comprising a rotor and a stator, comprising: a trigger electronic switch; The trigger circuit of this trigger electronic switch; And a blocking circuit for controlling a trigger pulse of the trigger electronic switch, wherein the blocking circuit maintains its blocking state while there is a voltage induced in the coils of the motor by the rotation of the rotor, so that the induced voltage This is achieved by means of a single phase induction motor starting electronic circuit which remains in the interrupted state for some constant time after this substantially decreases.
EMBODIMENT OF THE INVENTION Hereinafter, the invention of division is demonstrated with reference to an accompanying drawing.

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1 is a diagram schematically showing a complete electronic circuit of a first embodiment of the present invention.

2 is a diagram schematically showing a second embodiment of the electronic circuit of the invention.

3 is a schematic representation of the observed electrical response over time at different points of the electronic circuit of the invention.

The present invention operates in conjunction with an alternating current (F), as shown in FIGS. 1 and 2, and has at least one driving coil (B1) and a starting coil (B2), a rotor and a stator (these are shown A single phase induction motor of the type, i.e., an electronic circuit for starting the motor M will be described.

According to the invention, the present invention provides a trigger electronic switch; A trigger circuit TR of this trigger electronic switch; And a blocking circuit BL for controlling the trigger pulses of the trigger electronic switch, described below.

According to the invention, the blocking circuit BL provides a power off state of the trigger pulses of the trigger electronic switch, which will be described below, which power off state is induced in the winding of the motor M by the rotation of the rotor. The voltage persists for the duration of its existence and remains constant for some time after the induced voltage is substantially reduced.

According to the invention, the blocking circuit BL comprises electronic switch elements which are kept in a state of blocking the trigger pulses of the trigger electronic switch by the timer of the blocking circuit BL, described below. In this solution, the electronic switch elements are kept blocked by their voltage saturation.

In the structure shown, the trigger electronic switch is, for example, a triac S, the timer is a charging element, which is fed by the start-up circuit DP (FIG. 1), and also in FIG. As shown, it may be connected to a common point CO connecting the coils of the motor M.

1 and 2, the power source F is connected to the driving coil B1 of the motor M, and to the common point CO of each of the driving coil B1 and the starting coil B2, respectively. It has terminals 1 and 2.

The starting coil B2 is also connected to the terminal A of the starting circuit DP, the terminal B of the starting circuit DP is connected to the terminal 2 of the power supply F, and the starting coil B2. The driving capacitor Cp is connected between the terminal and the terminal 2 of the power supply F.

The triac S is connected between the terminal A of the starting circuit DP and the terminal B, so that the first anode A1 of the triac S is connected to the terminal of the starting circuit DP. Is connected to the terminal 2 of the power source F through B), and the second anode A2 is connected to the starting coil B2 and the driving capacitor of the motor M through the terminal A of the starting circuit DP. It is connected to Cp, and the trigger terminal G is connected to the trigger circuit TR.

Immediately after the motor M is energized by the power source F, the voltage between the terminal A2 and the terminal A1 of the triac S starts to rise.

As the voltage between the triac S terminal A1 and the terminal A2 rises in this manner, current flows in the trigger circuit TR.

According to the illustration of FIGS. 1 and 2, the trigger circuit TR comprises a first capacitor C1, one of the terminals of which is connected to the second anode A2 of the triac S. ), The other terminal is connected to one terminal of the first resistor R1, the other terminal of the first resistor R1 is connected to the anode of the first zener diode Z1, and the first zener diode The cathode of is connected to the cathode of the second zener diode Z2, the anode of the second zener diode Z2 is connected to the trigger terminal G of the triac S, and its trigger terminal G Is connected to the first terminal of the second capacitor C2 of the trigger circuit TR, and the second terminal of the second capacitor C2 is connected to the first anode A1 of the triac S.

The current flowing through the first resistor R1 and the first capacitor C1 is essentially limited by the value of the first capacitor.

The second capacitor C2 is provided between the trigger terminal G and the terminal A1 of the triac S, and has a low impedance to the high frequency current component, thereby preventing an accidental trigger of the triac.

The trigger current of the triac S flows through the first resistor R1 and the first capacitor C1, through the first and second zener diodes Z1 and Z2 and the trigger terminal of the triac S. Finding a path that flows through G) causes firing of the triac and consequent current conduction between terminals A1 and A2.

According to the present invention, the first and second Zener Ions Z1 and Z2 have a Zener voltage high enough to prevent current conduction through the Zener diodes when the blocking circuit BL is in the blocking state. In this solution, the zener voltages of the first and second zener diodes may be higher than 5 volts (V).

By conduction of the triac S, a current flows from the terminal 2 of the power supply F to the terminal A of the starting circuit DP, so that the starting coil B2 of the motor M is energized.

At the start of each half cycle of the alternating voltage supplied by the power source F, voltage fluctuations between the terminal A1 and the terminal A2 of the triac S are started, and the triac is carried out through the trigger circuit TR. This firing causes the triac S to conduct an alternating current and characterize the conduction state between the terminal A and the terminal B of the starting circuit DP.

1 and 2, the blocking circuit BL is composed of a complete rectifier bridge B1, which rectifies the anode of the first zener diode Z1 and the first capacitor C1. The connection permission includes a first input terminal connected to a common point; A second input terminal connected to the first anode A1 of the triac S; One terminal of the second resistor R2, one terminal of the third capacitor C3, for example, an emitter of the first transistor Q1 of the PNP type, one terminal of the fifth capacitor C5, and the third rectifier A positive output terminal connected to the anode of the diode D3; The other terminal of the second resistor R2, the anode of the first rectifier diode D1, one terminal of the fourth capacitor C4, one terminal of the third resistor R3, and a second, for example, NPN type. It has a negative output terminal connected to the emitter of transistor Q2.

The cathode of the first rectifier diode D1 is connected to the other terminal of the third capacitor C3 and the anode of the second rectifier diode D2, and the cathode of the second rectifier diode D2 is connected to the fourth capacitor C4. The other terminal of the third resistor R3, the other terminal of the fourth resistor R4, and the collector of the first transistor Q1, and the other terminal of the fourth resistor R4 Is connected to the base of the second transistor Q2, the base of the first transistor Q1 is connected to the other terminal of the fifth capacitor C5 and one terminal of the fifth resistor R5, and the fifth resistor R5. Is connected to the collector of the second transistor Q2 and the cathode of the fourth rectifier diode D4, and the anode of the fourth rectifier diode D4 is connected to the cathode of the third rectifier diode D3. .

In this solution, the transistors define the electronic switch element of the blocking circuit BL. When the first and second transistors Q1 and Q2 are not in a conductive state, the maximum voltage at point V1 is typically about 1.5 V with the voltages of the first and second zener diodes Z1 and Z2. It is essentially the same as the sum of the conducted voltages of the trigger terminals G of the liquids S. The voltages of the first and second zener diodes Z1 and Z2 are usually selected to be about 5 V, defining a point between the first resistor R1 and the rectifier bridge B1 at the intersection with the second zener diode Z2. Ensure that the maximum voltage observed at (V1) is approximately 6.5 V.

In the preferred structure of the present invention, as shown in Fig. 1, the wave rectifier bridge B1 has its positive output terminal connected to the point T1 of the blocking circuit BL, and the negative output terminal is the blocking circuit BL. Is connected to a point T2, and a resistor R2 is connected between the points T1 and T2 so that the voltage between these points is ringed when no current flows from the rectifier bridge B1. . During the initial operation period TX of the motor M immediately after energizing by the power source F, the voltage between the points V1 and A1 is in the form of a pulse wave, as shown in FIG. And the sum of the zener voltage values of the second zener diodes Z1 and Z2 and the conduction voltage of the trigger terminal G of the triac S.

During the same initial operation period TX of the motor M, the voltage between the points T1 and T2 of the blocking circuit BL is of the pulse shape with positive polarity as shown in FIG.

In the embodiment shown in FIG. 2, one terminal of the third capacitor C3 of the blocking circuit BL is connected to the starter coil B2 through the resistor R6 and blocked through the second rectifier diode D2. A current path to the fourth capacitor C4, which is a timer of the circuit BL, is formed.

During the initial period TX, current flows through the resistor R6 and the third capacitor C3, which causes a gradual voltage increment of the fourth capacitor C4, as shown in FIG.

The second rectifier diode D2 causes a current to flow only in order to increase the voltage of the fourth capacitor C4 during a time interval in which the voltage of the terminal 1 of the power source F is increasing, and the first rectifier diode ( When the voltage at the terminal 1 of the power source F is decreasing, D1 causes a current to flow through the third capacitor C3 to reestablish the initial voltage state of the third capacitor C3.

The voltage of the fourth capacitor C4 is reduced in small steps, the amplitude of which is essentially due to the ratio between the capacitor C3 and the capacitor C4 and the voltage induced at the terminal 1 of the power source F. It is prescribed.

In the embodiment of FIG. 1, current flows through the third capacitor C3 by the voltage pulse between the point T1 and the point T2 during the initial period TX, as shown in FIG. 3, Induces a gradual voltage increment of the fourth capacitor (C4). The second diode D2 causes current to flow only to increase the voltage of the fourth capacitor C4 during the time interval in which the pulse voltage is increasing, and the pulse voltage of the first rectifier diode D1 is decreasing. At this time, current flows through the third capacitor C3 to reestablish the initial voltage state of the third capacitor C3. The voltage of the fourth capacitor C4 increases in small steps, the amplitude of which is due to the ratio between the capacitances of the third capacitor C3 and the fourth capacitor C4 and the voltage characteristic at the point T1. It is essentially defined.

According to the illustration of FIGS. 1 and 2, the fourth capacitor C4 is connected in parallel with a third resistor R3 which causes the discharge of the fourth capacitor C4 when the system is off and the motor is at a standstill. It is. This time constant for discharging the fourth capacitor C4 should be greater than the entire cycle of the alternating voltage from the power source F.

As shown in FIG. 3, the voltage of the fourth capacitor C4 increases until it reaches a value (approximately 0.6 V) sufficient to polarize the base-emitter junction of the second transistor Q2. In essence, currents coming from the base of the first transistor Q1 and the fourth diode D4 flow through the collector of the second transistor Q2. As such, current flows through the base of the first transistor Q1, and current flows through the collector-emitter junction of the first transistor Q1, thereby further increasing the voltage of the fourth capacitor C4. This process takes place in the form of avalanche, defining the end of the period TX shown in FIG. As a result, the first and second transistors Q1 and Q2 are saturated to establish a final equilibrium state in which the collector of the second transistor Q2 has a voltage value close to 0.2 V with respect to the point T2. The voltage at T1 is essentially limited to the voltage drop of the third and fourth rectifier diodes D3, D4 added to the 0.2 V value present in the collector of the second transistor Q2, typically about 1.4 It becomes V.

In this final equilibrium state, after the time period TX has elapsed, the voltage of the fourth capacitor C4 drops the voltage drop at the emitter-collector junction of the first transistor Q1 at the maximum voltage at point T. It is essentially the same as minus, typically 1.2 V, which is much greater than the minimum required to impart the polarity of the base-emitter junction of the second transistor Q2 to ensure saturation of the transistor.

The current value at the base of the second transistor Q2 is limited by the fourth capacitor C4, and the current at the base of the first transistor Q1 is limited by the fifth resistor R5. The circuit has a fifth capacitor C5 disposed between the point T1 and the base of the first transistor Q1 to avoid sudden voltage fluctuations at the base of the transistor, thereby avoiding external electrical noise. It is prevented that the polarity of the transistor is caused when the high frequency noise of X is inadequate.

After this time period TX has elapsed, the final equilibrium condition limits the voltage at point T1 to a value typically close to 1.2 V, thereby limiting the voltage between point V1 and point A1. Limiting to a peak value close to 2.4 V to prevent current from flowing through the first and second diodes Z1 and Z2, which typically exhibit a zener voltage of about 5 V, thereby triggering the trigger current to the triac S. It prevents the flow through the terminal (G) of the, prevents current from flowing across the terminal (A1) and the terminal (A2) of the triac (S), characterized by the blocking state of the start switch of the motor. That is, the current management operation period of the motor M is characterized.

In this state, after the period TX has elapsed, the saturation of the first and second transistors Q1, Q2 is ensured by the operating state itself due to the voltage amplitude observed between the points T1 and T2. do. The voltage amplitude is high enough to hold the fourth capacitor C4 charged to a voltage level that is much greater than the minimum required to initiate the avalanche saturation process of the first and second transistors Q1, Q2. Therefore, while there is a voltage between the terminal A and the terminal B of the starting device TR, the blocking circuit BL has its blocking state due to saturation of the first and second transistors Q1 and Q2. Lasts. Even when the power source F is off, due to the voltage induced in the coils B1 and B2 of the motor M by the rotation of the rotor, this voltage between the points A and B exists, Even in the absence of a voltage between the terminal T1 and the terminal T2, for a certain time due to the fact that the voltage present in the fourth capacitor C4 is higher than the saturation level of the junction of the second capacitor C2. The saturation state of transistors Q1 and Q2 continues. In the absence of voltage between terminal T1 and terminal T2, this additional conduction time of transistors Q1 and Q2 is defined by the time constant and R4. Even when there is no voltage supplied by the power source F, when the voltage between the points A and B is already at a very low level, an additional time conduction state after the motor movement is substantially or completely reduced By this feature of the blocking circuit BL, which maintains the voltage, the starting device DP is not affected by the voltage interruption at the power supply, and the triac S is operated when the driving capacitor Cp has a high voltage. There is no danger.

According to the present invention, a simple method of avoiding damage to motor components due to excessive voltage overload due to power supply transients, disturbances, and interruptions caused by the power supply of the motor, without changing the energy consumption conditions of the motor, is simple. A structure and low cost single phase induction motor starting electronic circuit are provided.

Claims (14)

An electronic circuit for operating a single-phase induction motor of a type operating in association with an AC power source F, having at least one driving coil B1 and one starting coil B2, comprising a rotor and a stator, An electronic circuit for starting a single-phase induction motor comprising a trigger electronic switch, a trigger circuit TR of the trigger electronic switch, and a blocking circuit BL for controlling a trigger pulse of the trigger electronic switch. The blocking circuit BL continues its blocking state while there is a voltage induced in the coils of the motor M by the rotation of the rotor, so that the blocking circuit for a predetermined time after the induced voltage is reduced. An electronic circuit for starting a single-phase induction motor, the state being maintained. The single phase as claimed in claim 1, wherein the blocking circuit BL includes electronic switch elements which are held in a state of blocking the trigger pulses of the trigger electronic switch by a timer of the blocking circuit BL. Electronic circuit for starting induction motors. 3. The electronic circuit for starting a single phase induction motor according to claim 2, wherein the electronic switch elements are kept in a blocked state by voltage saturation. 4. The electronic circuit for starting a single phase induction motor according to claim 3, wherein the electronic switch elements are transistors (Q1, Q2). 5. The electronic circuit for starting a single phase induction motor according to claim 4, wherein the timer is a charging element. 6. The electronic circuit for starting a single phase induction motor according to claim 5, wherein the timer is powered by the trigger circuit (TR). 7. The trigger electronic switch according to claim 6, wherein the trigger electronic switch is connected in series with a first anode A1 connected to one terminal of the AC current power source, a start coil B2 of the motor M, and the start coil B2. Single phase induction, characterized in that the triac (S) having a second anode (A2) connected to one terminal of the driving capacitor (Cp) connected to, and the trigger terminal (G) connected to the trigger circuit (TR) Electronic circuit for starting the motor. The method of claim 7, wherein the trigger circuit (TR) comprises a first capacitor (C1), one terminal of the first capacitor (C1) is connected to the second anode (A2) of the triac (S) The other terminal is connected to one terminal of the first resistor R1, the other terminal of the first resistor R1 is connected to the anode of the first zener diode Z1, and the first zener diode Z1. ) Is connected to the cathode of the second zener diode (Z2), the anode of the second zener diode (Z2) is connected to the trigger terminal (G) of the tracer (S) Starting electronic circuit. The method of claim 8, wherein the trigger terminal (G) of the triac (S) is connected to the first terminal of the second capacitor (C2) of the start circuit (TR), the second of the second capacitor (C2) An electronic circuit for starting a single-phase induction motor, characterized in that the terminal is connected to the first anode (A1) of the triac (S). The method of claim 9, wherein the first and second zener diodes Z1 and Z2 are configured to conduct current conduction in the first and second zener diodes Z1 and Z2 when the blocking circuit BL is in a blocking state. An electronic circuit for starting a single-phase induction motor, having a zener voltage high enough to prevent it. 11. The electronic circuit for starting a single phase induction motor according to claim 10, wherein the zener voltages of the first and second zener diodes (Z1, Z2) are higher than 5 volts. The method of claim 11, wherein the blocking circuit BL is formed by a complete rectifier bridge, and the rectifier bridge connects the anode of the first zener diode Z1 and the first capacitor C1. A first input terminal connected to a common point; A second input terminal connected to the first anode A1 of the triac S; One terminal of the second resistor R2, one terminal of the third capacitor C3, the emitter of the first transistor Q1, one terminal of the fifth capacitor C5, and the anode of the third rectifier diode D3. A positive output terminal connected to; The other terminal of the second resistor R2, the anode of the first rectifier diode D1, one terminal of the fourth capacitor C4, one terminal of the third resistor R3, and the second transistor Q2 A negative output terminal connected to the emitter, the cathode of the first rectifier diode D1 is connected to the other terminal of the third capacitor C3 and the anode of the second rectifier diode D2, The cathode of the second rectifier diode D2 is the other terminal of the fourth capacitor C4, the other terminal of the third resistor R3, one terminal of the fourth resistor R4, and the first transistor. Is connected to the collector of Q1, the other terminal of the fourth resistor R4 is connected to the base of the second transistor Q2, and the base of the first transistor Q1 is connected to the fifth capacitor C5. And the other terminal of the fifth resistor R5, and the other terminal of the fifth resistor R5 And the anode of the fourth rectifier diode D4 is connected to the cathode of the third rectifier diode D3 and the collector of the second transistor Q2 and the cathode of the fourth rectifier diode D4. Electronic circuit for starting single-phase induction motor. 13. The electronic circuit for starting a single phase induction motor according to claim 12, wherein the first transistor (Q1) is of PNP type and the second transistor (Q2) is of NPN type. 13. The electronic circuit for starting a single phase induction motor according to claim 12, wherein said timer is defined by said fourth capacitor (C4).

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