A dual-switch mode motor starter control circuit

Abstract

This utility model relates to a dual-switch mode motor starter control circuit, belonging to the field of single-phase asynchronous motor starting. The utility model includes a current transformer, a first bidirectional thyristor, and a second bidirectional thyristor. The current transformer is designed with a primary coil, a first secondary coil, and a second secondary coil. The primary coil is connected in series with the main winding of the motor to form a motor operating circuit. The first and second bidirectional thyristors are connected in series with the auxiliary winding of the motor to form a motor starting circuit. Its structural feature is that it also includes a high-resistance resistor connected to the motor starting circuit. The trigger terminals (G) of the first and second bidirectional thyristors are connected in series with the first and second secondary coils, respectively. By sensing the current change in the motor operating circuit, the first and second bidirectional thyristors are controlled to turn on and off, respectively.

Description

Technical Field

[0001] This utility model relates to a dual-switch mode motor starter control circuit, belonging to the field of single-phase asynchronous motor starting. It is mainly used for starting the motors of refrigerator, freezer, and air conditioner compressors, and can also be used for starting other single-phase asynchronous motors. Background Technology

[0002] Currently, the fixed-frequency refrigeration compressors used in refrigerators, freezers, and air conditioners generally employ single-phase asynchronous motors. A single-phase asynchronous motor typically consists of a rotor and a stator, with the stator composed of a main winding and an auxiliary winding. The auxiliary winding, besides its function as a starter, also assists in the motor's operation during normal operation, improving its efficiency. Therefore, a complete auxiliary winding circuit can usually be represented by a parallel auxiliary winding operating circuit and an auxiliary winding starting circuit. When the motor is powered on, both the main and auxiliary windings are energized simultaneously. The current flowing through the windings generates an alternating rotating magnetic field on the stator, causing the rotor to begin rotating. As the rotor torque increases, the speed gradually increases. Generally, when the speed reaches 75%-80% or more of the rated speed, the auxiliary winding circuit should be disconnected. At this point, the motor can continue to accelerate until it reaches the rated speed and enters normal operation. The connection and disconnection of the auxiliary winding are accomplished by the starter.

[0003] Currently used starters include PTC starters, electronic starters, and voltage or current starters.

[0004] PTC starters utilize the R / T characteristics of PTC thermistors to achieve starting. When the motor starts, because the resistance of the PTC is low at room temperature, the current flowing through the secondary winding is large, causing the PTC to heat up and its resistance to rise rapidly. When the temperature reaches the Curie point, the resistance can reach several thousand ohms or more, reducing the current in the secondary winding circuit to about ten milliamps, thus essentially cutting off the secondary winding. After starting, in order to maintain the high resistance state of the PTC element, a holding current of about ten milliamps still flows through the PTC element. This holding current will generate about 3W of power consumption, resulting in a large waste of electrical energy. To reduce this power consumption, the current approach is to add a bidirectional thyristor and a trigger PTC that controls the on / off state of the bidirectional thyristor to the PTC starter. The working principle is to use the trigger current of the series circuit of the trigger PTC and the trigger junction of the bidirectional thyristor to control the main switch of the bidirectional thyristor to delay the shutdown of the starting circuit, thus eliminating the power consumption of about 3W generated by the starting PTC. However, in order to maintain the heat of the trigger PTC and keep it in a high-resistance state, a small current still flows through the trigger circuit, which will generate a power consumption of about 0.5W.

[0005] Electronic starters work by using electronic circuits to control the on / off state of the starting circuit switch. Currently used electronic starters generally have complex circuit designs and numerous electronic components, resulting in higher manufacturing costs, increased reliability risks, and a certain amount of power consumption. Therefore, their application in the market is not widespread.

[0006] The working principle of a current-type starter is to control the on / off state of the auxiliary winding circuit by utilizing the change in the main winding circuit current during the motor's starting / running state. When the motor starts, the main winding circuit current is relatively large, and the auxiliary winding circuit is connected through current sensing, thus starting the motor. After the motor starts, the main winding circuit current decreases, controlling the auxiliary winding circuit to disconnect. The working principle of a voltage-type starter is to control the on / off state of the starting circuit by sampling the voltage change across the auxiliary winding. When the motor starts, the voltage across the auxiliary winding is relatively low, and the starting circuit is in a closed state. After the motor starts, the voltage across the auxiliary winding gradually increases, controlling the starting circuit to disconnect. When a mechanical contact switch is used in the starting circuit, the current-type starter uses a weighted current relay; the voltage-type starter uses a voltage relay. When an electronic contactless switch is used in the starting circuit, the electronic switch is generally controlled electronically or electromagnetically.

[0007] Electronic switches commonly use triacs (SCRs). In current market applications, most starters connect a positive temperature coefficient (PTC) thermistor in series with the starter circuit. This is a configuration where the PTC is connected between the anodes of the triac. Besides improving the stability of the triac's delayed turn-off, this also prevents the secondary winding from remaining continuously connected when the triac short-circuits, which could lead to abnormal motor operation or even motor burnout. With the PTC in series, the starter can still start the motor after a triac short-circuit, although this will result in some power consumption as it is a conventional PTC starter.

[0008] However, the introduction of a positive temperature coefficient (PTC) thermistor limits the range of applications for the starter. Due to the power limitation of the PTC element itself, this type of starter can only be used on small to medium power motors. Currently, most high-power motors such as commercial compressors still use weighted current relays and voltage relays for starting. The mechanical contacts used in these relays pose significant risks. Firstly, the short lifespan and poor explosion-proof performance of these mechanical contacts urgently need to be addressed. Secondly, the motor damage caused by contact adhesion is also a serious concern. The aforementioned electronic switch starter with a series connection of a bidirectional thyristor anode and a positive temperature coefficient thermistor (PTC), while capable of starting high-power motors by eliminating the PTC and using a high-current bidirectional thyristor, still carries the risk of short circuit in the starter due to anode breakdown of the bidirectional thyristor. This could prevent the motor's auxiliary winding circuit from shutting off, leading to abnormal motor operation or damage. Although the probability of anode breakdown of the bidirectional thyristor is extremely low, the resulting damage is significant, and improvements are needed to minimize this risk. Utility Model Content

[0009] The purpose of this invention is to overcome the above-mentioned shortcomings in the existing technology. Through circuit optimization design, a motor starter control circuit with a reasonable dual-switch mode is provided. That is, two bidirectional thyristors are connected in series in the anode circuit. This type of starting control circuit will only cause a short circuit in the starter when both bidirectional thyristors break down between their anodes at the same time. Compared with the starting circuit using a single bidirectional thyristor, the probability of short circuit can be reduced, making the starter safer and more reliable.

[0010] The technical solution adopted by this utility model to solve the above problems is as follows: the dual-switch mode motor starter control circuit includes a current transformer, a first bidirectional thyristor, and a second bidirectional thyristor. The current transformer is designed with a primary coil, a first secondary coil, and a second secondary coil. The primary coil is connected in series with the main winding of the motor to form a motor running circuit. The first and second bidirectional thyristors are connected in series with the auxiliary winding of the motor to form a motor starting circuit. Its structural feature is that it also includes a high-resistance resistor, which is connected to the motor starting circuit. The trigger terminals G of the first and second bidirectional thyristors are connected in series with the first and second secondary coils, respectively. The first and second bidirectional thyristors are turned on and off by sensing the current change in the motor running circuit.

[0011] Furthermore, terminal 1 of the primary coil is connected to terminal M of the main winding of the motor; terminal 3 of the first secondary coil is connected to terminal A1 of the first bidirectional thyristor and terminal S of the auxiliary winding of the motor; terminal 4 of the first secondary coil is connected to terminal G of the trigger electrode of the first bidirectional thyristor; terminal 5 of the second secondary coil is connected to terminal A2 of the second bidirectional thyristor, terminal A1 of the first bidirectional thyristor, and one end of the high-resistivity resistor; terminal 6 of the second secondary coil is connected to terminal G of the trigger electrode of the second bidirectional thyristor; terminal A2 of the second bidirectional thyristor is connected to terminal 2 of the primary coil, the other end of the high-resistivity resistor, and terminal N of the AC power supply; and terminal C of the motor is connected to terminal L of the AC power supply.

[0012] Furthermore, terminal 1 of the primary coil is connected to terminal M of the main winding of the motor; terminal 3 of the first secondary coil is connected to terminal A1 of the first bidirectional thyristor, one end of the high-resistivity resistor, and terminal S of the auxiliary winding of the motor; terminal 4 of the first secondary coil is connected to terminal G of the trigger electrode of the first bidirectional thyristor; terminal 5 of the second secondary coil is connected to terminal A2 of the second bidirectional thyristor, terminal A1 of the first bidirectional thyristor, and the other end of the high-resistivity resistor; terminal 6 of the second secondary coil is connected to terminal G of the trigger electrode of the second bidirectional thyristor; terminal A2 of the second bidirectional thyristor is connected to terminal 2 of the primary coil and terminal N of the AC power supply; and terminal C of the motor is connected to terminal L of the AC power supply.

[0013] Furthermore, terminal 1 of the primary coil is connected to terminal M of the main winding of the motor; terminal 3 of the second secondary coil is connected to terminal A1 of the first bidirectional thyristor and terminal S of the auxiliary winding of the motor; terminal 4 of the second secondary coil is connected to terminal G of the trigger electrode of the first bidirectional thyristor; terminal 5 of the second secondary coil is connected to terminal A2 of the first bidirectional thyristor, terminal A1 of the second bidirectional thyristor, and one end of the high-resistivity resistor; terminal 6 of the second secondary coil is connected to terminal G of the trigger electrode of the second bidirectional thyristor; terminal A2 of the second bidirectional thyristor is connected to terminal 2 of the primary coil and terminal N of the AC power supply; and the other end of the high-resistivity resistor is connected to terminal C of the motor and terminal L of the AC power supply.

[0014] Furthermore, terminal 1 of the primary coil is connected to terminal M of the main winding of the motor; terminal 3 of the first secondary coil is connected to terminal G of the trigger electrode of the first bidirectional thyristor; terminal 4 of the first secondary coil is connected to terminal A1 of the first bidirectional thyristor, terminal A2 of the second bidirectional thyristor, and one end of the high-resistivity resistor; terminal 5 of the second secondary coil is connected to terminal G of the trigger electrode of the second bidirectional thyristor; terminal 6 of the second secondary coil is connected to terminal A1 of the second bidirectional thyristor, terminal 2 of the primary coil, the other end of the high-resistivity resistor, and terminal N of the AC power supply; terminal A2 of the first bidirectional thyristor is connected to terminal S of the auxiliary winding of the motor; and terminal C of the motor is connected to terminal L of the AC power supply.

[0015] Furthermore, terminal 1 of the primary coil is connected to terminal M of the main winding of the motor; terminal 3 of the first secondary coil is connected to terminal G of the trigger electrode of the first bidirectional thyristor; terminal 4 of the first secondary coil is connected to terminal A1 of the first bidirectional thyristor, terminal A2 of the second bidirectional thyristor, and one end of the high-resistivity resistor; terminal 5 of the second secondary coil is connected to terminal G of the trigger electrode of the second bidirectional thyristor; terminal 6 of the second secondary coil is connected to terminal A1 of the second bidirectional thyristor, terminal 2 of the primary coil, and terminal N of the AC power supply; terminal A2 of the first bidirectional thyristor is connected to the other end of the high-resistivity resistor and terminal S of the secondary winding of the motor; and terminal C of the motor is connected to terminal L of the AC power supply.

[0016] Furthermore, terminal 1 of the primary coil is connected to terminal M of the main winding of the motor; terminal 3 of the first secondary coil is connected to terminal G of the trigger electrode of the first bidirectional thyristor; terminal 4 of the first secondary coil is connected to terminal A1 of the first bidirectional thyristor, terminal A2 of the second bidirectional thyristor, and one end of the high-resistivity resistor; terminal 5 of the second secondary coil is connected to terminal G of the trigger electrode of the second bidirectional thyristor; terminal 6 of the second secondary coil is connected to terminal A1 of the second bidirectional thyristor, terminal 2 of the primary coil, and terminal N of the AC power supply; terminal A2 of the first bidirectional thyristor is connected to terminal S of the auxiliary winding of the motor; and the other end of the high-resistivity resistor is connected to terminal C of the motor and terminal L of the AC power supply.

[0017] Furthermore, a dual-switch mode motor starter control circuit includes a current transformer, a first bidirectional thyristor, a second bidirectional thyristor, and a first positive temperature coefficient thermistor. The current transformer is designed with a primary coil and a secondary coil. The primary coil is connected in series with the main winding of the motor to form a motor operating circuit. The first and second bidirectional thyristors are connected in series with the secondary winding of the motor to form a motor starting circuit. Its structural feature is that it also includes a high-resistance resistor, which is connected to the motor starting circuit. The trigger terminal (G) of the first bidirectional thyristor is connected in series with the secondary coil, and the switching on and off of the first bidirectional thyristor is controlled by sensing the current change in the motor operating circuit. The trigger terminal (G) of the second bidirectional thyristor is connected in series with the first positive temperature coefficient thermistor, and the switching on and off of the second bidirectional thyristor is controlled by utilizing the R / T characteristics of the first positive temperature coefficient thermistor.

[0018] Furthermore, terminal 1 of the primary coil is connected to terminal M of the main winding of the motor; terminal 3 of the secondary coil is connected to terminal A1 of the first anode of the first bidirectional thyristor and terminal S of the auxiliary winding of the motor; terminal 4 of the secondary coil is connected to terminal G of the trigger electrode of the first bidirectional thyristor; terminal A2 of the first bidirectional thyristor is connected to terminal A2 of the second anode of the second bidirectional thyristor and one end of the high-resistivity resistor; terminal G of the second bidirectional thyristor is connected to one end of the first positive temperature coefficient thermistor; the other end of the first positive temperature coefficient thermistor is connected to terminal C of the motor and terminal L of the AC power supply; and terminal A1 of the second bidirectional thyristor is connected to terminal 2 of the primary coil, the other end of the high-resistivity resistor, and terminal N of the AC power supply.

[0019] Furthermore, terminal 1 of the primary coil is connected to terminal M of the main winding of the motor; terminal 3 of the secondary coil is connected to one end of the high-resistivity resistor, terminal A1 of the first anode of the first bidirectional thyristor, and terminal S of the auxiliary winding of the motor; terminal 4 of the secondary coil is connected to terminal G of the trigger electrode of the first bidirectional thyristor; terminal A2 of the first bidirectional thyristor is connected to terminal A2 of the second bidirectional thyristor and the other end of the high-resistivity resistor; terminal G of the second bidirectional thyristor is connected to one end of the first positive temperature coefficient thermistor; the other end of the first positive temperature coefficient thermistor is connected to terminal C of the motor and terminal L of the AC power supply; and terminal A1 of the second bidirectional thyristor is connected to terminal 2 of the primary coil and terminal N of the AC power supply.

[0020] Furthermore, terminal 1 of the primary coil is connected to terminal M of the main winding of the motor; terminal 3 of the secondary coil is connected to terminal A1 of the first anode of the first bidirectional thyristor and terminal S of the auxiliary winding of the motor; terminal 4 of the secondary coil is connected to terminal G of the trigger electrode of the first bidirectional thyristor; terminal A2 of the first bidirectional thyristor is connected to terminal A2 of the second anode of the second bidirectional thyristor and one end of the high-resistivity resistor; terminal G of the second bidirectional thyristor is connected to one end of the first positive temperature coefficient thermistor; the other end of the first positive temperature coefficient thermistor is connected to the other end of the high-resistivity resistor, terminal C of the motor, and terminal L of the AC power supply; and terminal A1 of the second bidirectional thyristor is connected to terminal 2 of the primary coil and terminal N of the AC power supply.

[0021] Furthermore, terminal 1 of the primary coil is connected to terminal M of the main winding of the motor; terminal 3 of the secondary coil is connected to terminal G of the trigger electrode of the first bidirectional thyristor; terminal 4 of the secondary coil is connected to terminal A1 of the first bidirectional thyristor, terminal A2 of the second bidirectional thyristor, and one end of the high-resistivity resistor; terminal A2 of the first bidirectional thyristor is connected to terminal S of the auxiliary winding of the motor; terminal G of the second bidirectional thyristor is connected to one end of the first positive temperature coefficient thermistor; the other end of the first positive temperature coefficient thermistor is connected to terminal C of the motor and terminal L of the AC power supply; and terminal A1 of the second bidirectional thyristor is connected to terminal 2 of the primary coil, the other end of the high-resistivity resistor, and terminal N of the AC power supply.

[0022] Furthermore, terminal 1 of the primary coil is connected to terminal M of the main winding of the motor; terminal 3 of the secondary coil is connected to terminal G of the trigger electrode of the first bidirectional thyristor; terminal 4 of the secondary coil is connected to terminal A1 of the first bidirectional thyristor, terminal A2 of the second bidirectional thyristor, and one end of the high-resistivity resistor; terminal A2 of the first bidirectional thyristor is connected to the other end of the high-resistivity resistor and terminal S of the auxiliary winding of the motor; terminal G of the second bidirectional thyristor is connected to one end of the first positive temperature coefficient thermistor; the other end of the first positive temperature coefficient thermistor is connected to terminal C of the motor and terminal L of the AC power supply; and terminal A1 of the second bidirectional thyristor is connected to terminal 2 of the primary coil and terminal N of the AC power supply.

[0023] Furthermore, terminal 1 of the primary coil is connected to terminal M of the main winding of the motor; terminal 3 of the secondary coil is connected to terminal G of the trigger electrode of the first bidirectional thyristor; terminal 4 of the secondary coil is connected to terminal A1 of the first bidirectional thyristor, terminal A2 of the second bidirectional thyristor, and one end of the high-resistivity resistor; terminal A2 of the first bidirectional thyristor is connected to terminal S of the auxiliary winding of the motor; terminal G of the second bidirectional thyristor is connected to one end of the first positive temperature coefficient thermistor; the other end of the first positive temperature coefficient thermistor is connected to the other end of the high-resistivity resistor, terminal C of the motor, and terminal L of the AC power supply; and terminal A1 of the second bidirectional thyristor is connected to terminal 2 of the primary coil and terminal N of the AC power supply.

[0024] Furthermore, a dual-switch mode motor starter control circuit includes a first bidirectional thyristor, a second bidirectional thyristor, a first positive temperature coefficient (PTC) thermistor, and a second PTC thermistor. Its structural features are as follows: the second anode A2 terminal of the first bidirectional thyristor is connected to the auxiliary winding S terminal of the motor; the first anode A1 terminal of the first bidirectional thyristor is connected to the second anode A2 terminal of the second bidirectional thyristor; the trigger terminal G terminal of the first bidirectional thyristor is connected to one end of the first PTC thermistor; the first anode A1 terminal of the second bidirectional thyristor is connected to the main winding M terminal and the AC power supply N terminal of the motor; the trigger terminal G terminal of the second bidirectional thyristor is connected to one end of the second PTC thermistor; and the other end of the first PTC thermistor is connected to the other end of the second PTC thermistor, both of which are connected to the motor C terminal and the AC power supply L terminal.

[0025] Compared with existing technologies, this utility model has the following advantages: First, because it uses two bidirectional thyristor anodes connected in series, even if one of the bidirectional thyristors short-circuits, it will not cause the starter to short-circuit and can be used normally, thus greatly reducing the risk caused by starter short circuits; Second, because it uses an electronic switch, it can solve various problems existing in mechanical contacts; Third, when a positive temperature coefficient thermistor is connected in series in the secondary winding circuit, the PTC resistance will cause the starting current to decrease, which will have a certain impact on the motor starting performance. The power limitation of the PTC element also affects the range of motor power usage. Therefore, eliminating the positive temperature coefficient thermistor can effectively improve the motor starting performance and usage range.

[0026] It can effectively improve starting performance and has a wider range of applications. By adjusting the current parameters of the bidirectional thyristor, it can start motors of various power. The dual-switch series mode can effectively reduce the probability of short circuit in the starter. At the same time, compared with existing high-power motor starters, it can solve various problems caused by mechanical contacts. Attached Figure Description

[0027] Figure 1 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 1 of this utility model.

[0028] Figure 2 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 2 of this utility model.

[0029] Figure 3 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 3 of this utility model.

[0030] Figure 4 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 4 of this utility model.

[0031] Figure 5 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 5 of this utility model.

[0032] Figure 6 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 6 of this utility model.

[0033] Figure 7 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 7 of this utility model.

[0034] Figure 8 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 8 of this utility model.

[0035] Figure 9 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 9 of this utility model.

[0036] Figure 10 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 10 of this utility model.

[0037] Figure 11 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 11 of this utility model.

[0038] Figure 12 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 12 of this utility model.

[0039] Figure 13 This is a circuit diagram of the dual-switch mode motor starter control circuit of Embodiment 13 of this utility model.

[0040] In the diagram: current transformer CT, first bidirectional thyristor T1, second bidirectional thyristor T2, high-resistivity resistor R, primary coil P, secondary coil one K1, secondary coil two K2, first positive temperature coefficient thermistor PTC1, second positive temperature coefficient thermistor PTC2, motor MY. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and through embodiments. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.

[0042] Example

[0043] See Figures 1 to 13 As shown in the accompanying drawings, the structures, proportions, sizes, etc., depicted in this specification are merely for illustrative purposes to aid those skilled in the art and to provide a clear understanding. They are not intended to limit the scope of this invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or purpose of this invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the use of terms such as "upper," "lower," "left," "right," "middle," and "one" in this specification is solely for clarity and not intended to limit the scope of this invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this invention.

[0044] Examples 1-6, such as Figure 1-6 As shown: The dual-switch mode motor starter control circuit in this embodiment includes a high-resistance resistor R, a current transformer CT, a first bidirectional thyristor T1, and a second bidirectional thyristor T2. The current transformer CT is designed with a primary coil P, a second secondary coil K1, and a second secondary coil K2. The primary coil P is connected in series with the main winding of the motor MY to form a motor running circuit. The first anode A1-second anode A2 terminal of the first bidirectional thyristor T1 and the first anode A1-second anode A2 terminal of the second bidirectional thyristor T2 are connected in series with the secondary winding of the motor MY to form a motor starting circuit. The high-resistance resistor R is connected to the motor starting circuit. The trigger terminals G of the first bidirectional thyristor T1 and the second bidirectional thyristor T2 are connected in series with the second secondary coil K1 and the second secondary coil K2, respectively. By sensing the current change in the motor running circuit, the first bidirectional thyristor T1 and the second bidirectional thyristor T2 are controlled to turn on and off, respectively.

[0045] In Example 1, terminal 1 of the primary coil P is connected to terminal M of the main winding of motor MY. Terminal 3 of secondary coil K1 is connected to terminal A1 of the first anode of the first bidirectional thyristor T1 and terminal S of the secondary winding of motor MY. Terminal 4 of secondary coil K1 is connected to terminal G of the trigger electrode of the first bidirectional thyristor T1. Terminal 5 of secondary coil K2 is connected to terminal A2 of the second anode of the first bidirectional thyristor T1, terminal A1 of the first anode of the second bidirectional thyristor T2, and one end of the high-resistivity resistor R. Terminal 6 of secondary coil K2 is connected to terminal G of the trigger electrode of the second bidirectional thyristor T2. Terminal A2 of the second bidirectional thyristor T2 is connected to terminal 2 of the primary coil P, the other end of the high-resistivity resistor R, and terminal N of the AC power supply. Terminal C of motor MY is connected to terminal L of the AC power supply. Figure 1 As shown.

[0046] In Example 2, terminal 1 of the primary coil P is connected to terminal M of the main winding of motor MY. Terminal 3 of secondary coil K1 is connected to terminal A1 of the first anode of the first bidirectional thyristor T1, one end of the high-resistivity resistor R, and terminal S of the secondary winding of motor MY. Terminal 4 of secondary coil K1 is connected to terminal G of the trigger electrode of the first bidirectional thyristor T1. Terminal 5 of secondary coil K2 is connected to terminal A2 of the second anode of the first bidirectional thyristor T1, terminal A1 of the first anode of the second bidirectional thyristor T2, and the other end of the high-resistivity resistor R. Terminal 6 of secondary coil K2 is connected to terminal G of the trigger electrode of the second bidirectional thyristor T2. Terminal A2 of the second bidirectional thyristor T2 is connected to terminal 2 of the primary coil P and terminal N of the AC power supply. Terminal C of motor MY is connected to terminal L of the AC power supply. Figure 2 As shown.

[0047] In Example 3, terminal 1 of the primary coil P is connected to terminal M of the main winding of motor MY. Terminal 3 of secondary coil K1 is connected to terminal A1 of the first anode of the first bidirectional thyristor T1 and terminal S of the secondary winding of motor MY. Terminal 4 of secondary coil K1 is connected to terminal G of the trigger electrode of the first bidirectional thyristor T1. Terminal 5 of secondary coil K2 is connected to terminal A2 of the second anode of the first bidirectional thyristor T1, terminal A1 of the first anode of the second bidirectional thyristor T2, and one end of the high-resistivity resistor R. Terminal 6 of secondary coil K2 is connected to terminal G of the trigger electrode of the second bidirectional thyristor T2. Terminal A2 of the second bidirectional thyristor T2 is connected to terminal 2 of the primary coil P and terminal N of the AC power supply. The other end of the high-resistivity resistor R is connected to terminal C of motor MY and terminal L of the AC power supply. Figure 3 As shown.

[0048] In Example 4, terminal 1 of the primary coil P is connected to terminal M of the main winding of motor MY; terminal 3 of secondary coil K1 is connected to terminal G of the trigger electrode of the first bidirectional thyristor T1; terminal 4 of secondary coil K1 is connected to terminal A1 of the first anode of the first bidirectional thyristor T1, terminal A2 of the second anode of the second bidirectional thyristor T2, and one end of the high-resistivity resistor R; terminal 5 of secondary coil K2 is connected to terminal G of the trigger electrode of the second bidirectional thyristor T2; terminal 6 of secondary coil K2 is connected to terminal A1 of the first anode of the second bidirectional thyristor T2, terminal 2 of the primary coil P, the other end of the high-resistivity resistor R, and terminal N of the AC power supply; terminal A2 of the first bidirectional thyristor T1 is connected to terminal S of the secondary winding of motor MY; and terminal C of motor MY is connected to terminal L of the AC power supply. Figure 4 As shown.

[0049] In Example 5, terminal 1 of the primary coil P is connected to terminal M of the main winding of motor MY; terminal 3 of secondary coil K1 is connected to terminal G of the trigger electrode of the first bidirectional thyristor T1; terminal 4 of secondary coil K1 is connected to terminal A1 of the first anode of the first bidirectional thyristor T1, terminal A2 of the second anode of the second bidirectional thyristor T2, and one end of the high-resistivity resistor R; terminal 5 of secondary coil K2 is connected to terminal G of the trigger electrode of the second bidirectional thyristor T2; terminal 6 of secondary coil K2 is connected to terminal A1 of the first anode of the second bidirectional thyristor T2, terminal 2 of the primary coil P, and terminal N of the AC power supply; terminal A2 of the first bidirectional thyristor T1 is connected to the other end of the high-resistivity resistor R and terminal S of the secondary winding of motor MY; and terminal C of motor MY is connected to terminal L of the AC power supply. Figure 5 As shown.

[0050] In Example 6, terminal 1 of the primary coil P is connected to terminal M of the main winding of motor MY; terminal 3 of secondary coil K1 is connected to terminal G of the trigger electrode of the first bidirectional thyristor T1; terminal 4 of secondary coil K1 is connected to terminal A1 of the first anode of the first bidirectional thyristor T1, terminal A2 of the second anode of the second bidirectional thyristor T2, and one end of the high-resistivity resistor R; terminal 5 of secondary coil K2 is connected to terminal G of the trigger electrode of the second bidirectional thyristor T2; terminal 6 of secondary coil K2 is connected to terminal A1 of the first anode of the second bidirectional thyristor T2, terminal 2 of the primary coil P, and terminal N of the AC power supply; terminal A2 of the first bidirectional thyristor T1 is connected to terminal S of the secondary winding of motor MY; and the other end of the high-resistivity resistor R is connected to terminal C of motor MY and terminal L of the AC power supply. Figure 6 As shown.

[0051] Specifically, in embodiments 1-6: when the motor starts, the primary coil P connected in series with the main winding of the motor MY has a large current. By reasonably designing the turns ratio, magnetic flux and other parameters of the current transformer CT, the induced current of the secondary coil K1 and the secondary coil K2 can meet the turn-on triggering conditions of the first bidirectional thyristor T1 and the second bidirectional thyristor T2.

[0052] When the high-resistivity resistor R is connected to the N terminal of the AC power supply, a voltage exists between the first anode A1 and the second anode A2 of the first bidirectional thyristor T1, causing it to turn on first. Following the turn-on of the first bidirectional thyristor T1, a voltage also exists between the first anode A1 and the second anode A2 of the second bidirectional thyristor T2, causing it to turn on subsequently. Similarly, when the high-resistivity resistor R is connected to the S or C terminal of the secondary winding of the motor MY, a voltage exists between the first anode A1 and the second anode A2 of the second bidirectional thyristor T2, causing it to turn on first. Following the turn-on of the second bidirectional thyristor T2, the voltage also exists between the first anode A1 and the second anode A2 of the first bidirectional thyristor T1. After a voltage exists between the first anode A1 and the second anode A2, the circuit is turned on. With the simultaneous turn-on of the first bidirectional thyristor T1 and the second bidirectional thyristor T2, the motor starting circuit is connected, and the motor starts normally. After the motor starts, the current in the primary coil P connected in series in the motor running circuit decreases. Through electromagnetic induction, the induced currents in the secondary coils K1 and K2 also decrease. When the induced current cannot meet the triggering conditions of the first bidirectional thyristor T1 and the second bidirectional thyristor T2, they will both be turned off when the AC crosses zero. With the turn-off of the first bidirectional thyristor T1 and the second bidirectional thyristor T2, the motor starting process ends.

[0053] Examples 7-12, such as Figure 7-12 As shown: The dual-switch mode motor starter control circuit in this embodiment includes a high-resistance resistor R, a current transformer CT, a first bidirectional thyristor T1, a second bidirectional thyristor T2, and a first positive temperature coefficient thermistor PTC1. The current transformer CT is designed with a primary coil P and a secondary coil K1. The primary coil P is connected in series with the main winding of the motor MY to form the motor running circuit. The first anode A1 terminal of the first bidirectional thyristor T1 is connected to the second anode A2 terminal, and the first anode A1 terminal of the second bidirectional thyristor T2 is connected to the second anode A2 terminal. Terminal A2 is connected in series with the secondary winding of motor MY to form a motor starting circuit. The high-resistance resistor R is connected to the motor starting circuit. The trigger terminal G of the first bidirectional thyristor T1 is connected in series with the secondary coil K1. The switching on and off of the first bidirectional thyristor T1 is controlled by sensing the current change in the motor running circuit. The trigger terminal G of the second bidirectional thyristor T2 is connected in series with the first positive temperature coefficient thermistor PTC1. The switching on and off of the second bidirectional thyristor T2 is controlled by the R / T characteristic of the first positive temperature coefficient thermistor PTC1.

[0054] In Example 7, terminal 1 of the primary coil P is connected to terminal M of the main winding of motor MY. Terminal 3 of the secondary coil K1 is connected to terminal A1 of the first anode of the first bidirectional thyristor T1 and terminal S of the secondary winding of motor MY, respectively. Terminal 4 of the secondary coil K1 is connected to terminal G of the trigger electrode of the first bidirectional thyristor T1. Terminal A2 of the first bidirectional thyristor T1 is connected to terminal A2 of the second anode of the second bidirectional thyristor T2 and one end of the high-resistivity resistor R, respectively. Terminal G of the second bidirectional thyristor T2 is connected to one end of the first positive temperature coefficient thermistor PTC1. The other end of the first positive temperature coefficient thermistor PTC1 is connected to terminal C of motor MY and terminal L of AC power supply, respectively. Terminal A1 of the second bidirectional thyristor T2 is connected to terminal 2 of the primary coil P, the other end of the high-resistivity resistor R, and terminal N of AC power supply, respectively. Figure 7 As shown.

[0055] In Example 8, terminal 1 of the primary coil P is connected to terminal M of the main winding of the motor MY. Terminal 3 of the secondary coil K1 is connected to one end of the high-resistivity resistor R, the first anode A1 of the first bidirectional thyristor T1, and the secondary winding S of the motor MY. Terminal 4 of the secondary coil K1 is connected to the trigger terminal G of the first bidirectional thyristor T1. Terminal A2 of the first bidirectional thyristor T1 is connected to the second anode A2 of the second bidirectional thyristor T2 and the other end of the high-resistivity resistor R. Terminal G of the second bidirectional thyristor T2 is connected to one end of the first positive temperature coefficient thermistor PTC1. The other end of the first positive temperature coefficient thermistor PTC1 is connected to terminal C of the motor MY and terminal L of the AC power supply. Terminal A1 of the second bidirectional thyristor T2 is connected to terminal 2 of the primary coil P and terminal N of the AC power supply. Figure 8 As shown.

[0056] In Example 9, terminal 1 of the primary coil P is connected to terminal M of the main winding of the motor MY. Terminal 3 of the secondary coil K1 is connected to terminal A1 of the first anode of the first bidirectional thyristor T1 and terminal S of the secondary winding of the motor MY, respectively. Terminal 4 of the secondary coil K1 is connected to terminal G of the trigger electrode of the first bidirectional thyristor T1. Terminal A2 of the first bidirectional thyristor T1 is connected to terminal A2 of the second anode of the second bidirectional thyristor T2 and one end of the high-resistivity resistor R, respectively. Terminal G of the second bidirectional thyristor T2 is connected to one end of the first positive temperature coefficient thermistor PTC1. The other end of the first positive temperature coefficient thermistor PTC1 is connected to the other end of the high-resistivity resistor R, terminal C of the motor MY, and terminal L of the AC power supply, respectively. Terminal A1 of the second bidirectional thyristor T2 is connected to terminal 2 of the primary coil P and terminal N of the AC power supply, respectively. Figure 9 As shown.

[0057] In Example 10, terminal 1 of the primary coil P is connected to terminal M of the main winding of motor MY; terminal 3 of the secondary coil K1 is connected to terminal G of the trigger electrode of the first bidirectional thyristor T1; terminal 4 of the secondary coil K1 is connected to terminal A1 of the first anode of the first bidirectional thyristor T1, terminal A2 of the second anode of the second bidirectional thyristor T2, and one end of the high-resistivity resistor R; terminal A2 of the first bidirectional thyristor T1 is connected to terminal S of the secondary winding of motor MY; terminal G of the second bidirectional thyristor T2 is connected to one end of the first positive temperature coefficient thermistor PTC1; the other end of the first positive temperature coefficient thermistor PTC1 is connected to terminal C of motor MY and terminal L of AC power supply; terminal A1 of the second bidirectional thyristor T2 is connected to terminal 2 of the primary coil P, the other end of the high-resistivity resistor R, and terminal N of AC power supply. Figure 10 As shown.

[0058] In Example 11, terminal 1 of the primary coil P is connected to terminal M of the main winding of motor MY; terminal 3 of the secondary coil K1 is connected to terminal G of the trigger electrode of the first bidirectional thyristor T1; terminal 4 of the secondary coil K1 is connected to terminal A1 of the first anode of the first bidirectional thyristor T1, terminal A2 of the second anode of the second bidirectional thyristor T2, and one end of the high-resistivity resistor R; terminal A2 of the first bidirectional thyristor T1 is connected to the other end of the high-resistivity resistor R and terminal S of the secondary winding of motor MY; terminal G of the trigger electrode of the second bidirectional thyristor T2 is connected to one end of the first positive temperature coefficient thermistor PTC1; the other end of the first positive temperature coefficient thermistor PTC1 is connected to terminal C of motor MY and terminal L of AC power supply; terminal A1 of the second bidirectional thyristor T2 is connected to terminal 2 of the primary coil P and terminal N of AC power supply. Figure 11 As shown.

[0059] In Example 12, terminal 1 of the primary coil P is connected to terminal M of the main winding of motor MY; terminal 3 of the secondary coil K1 is connected to terminal G of the trigger electrode of the first bidirectional thyristor T1; terminal 4 of the secondary coil K1 is connected to terminal A1 of the first anode of the first bidirectional thyristor T1, terminal A2 of the second anode of the second bidirectional thyristor T2, and one end of the high-resistivity resistor R; terminal A2 of the first bidirectional thyristor T1 is connected to terminal S of the secondary winding of motor MY; terminal G of the second bidirectional thyristor T2 is connected to one end of the first positive temperature coefficient thermistor PTC1; the other end of the first positive temperature coefficient thermistor PTC1 is connected to the other end of the high-resistivity resistor R, terminal C of motor MY, and terminal L of AC power supply; terminal A1 of the second bidirectional thyristor T2 is connected to terminal 2 of the primary coil P and terminal N of AC power supply. Figure 12 As shown.

[0060] Specifically, in embodiments 7-12: when the motor starts, the primary coil P connected in series with the main winding of the motor MY has a large current. By reasonably designing the turns ratio, magnetic flux and other parameters of the current transformer CT, the induced current of the secondary coil K1 meets the turn-on triggering condition of the first bidirectional thyristor T1; while the first positive temperature coefficient thermistor PTC1 in the cold state has a low resistance value, and the circuit triggering current also meets the turn-on triggering condition of the second bidirectional thyristor T2.

[0061] When the high-resistivity resistor R is connected to the N terminal of the AC power supply, under the action of the high-resistivity resistor R, the first anode A1 terminal and the second anode A2 terminal of the first bidirectional thyristor T1 are turned on first due to the existence of a terminal voltage. As the first bidirectional thyristor T1 is turned on, the first anode A1 terminal and the second anode A2 terminal of the second bidirectional thyristor T2 are also turned on after the existence of a terminal voltage. When the high-resistivity resistor R is connected to the S or C terminal of the auxiliary winding of the motor MY, under the action of the high-resistivity resistor R, the first anode A1 terminal and the second anode A2 terminal of the second bidirectional thyristor T2 are turned on first due to the existence of a terminal voltage. As the second bidirectional thyristor T2 is turned on, the first anode A1 terminal and the second anode A2 terminal of the first bidirectional thyristor T1 are also turned on after the existence of a terminal voltage. When both bidirectional thyristor T1 and T2 are turned on simultaneously, the motor starting circuit is activated, and the motor starts normally. After the motor starts, the current in the primary coil P decreases. Through electromagnetic induction, the induced current in the secondary coil K1 also decreases. When the induced current cannot meet the triggering condition of the first bidirectional thyristor T1, T1 turns off when the AC zero crosses. At the same time, the resistance of the positive temperature coefficient thermistor PTC tends to its maximum value under the influence of its R / T characteristic, and the triggering current of the second bidirectional thyristor T2 decreases. When the triggering condition cannot be met, T2 also turns off when the AC zero crosses. With the turn-off of both T1 and T2, the motor starting process ends.

[0062] Example 13, as Figure 13As shown: The dual-switch mode motor starter control circuit in this embodiment includes a first bidirectional thyristor T1, a second bidirectional thyristor T2, a first positive temperature coefficient thermistor PTC1, and a second positive temperature coefficient thermistor PTC2. Its features are: the second anode A2 terminal of the first bidirectional thyristor T1 is connected to the secondary winding S terminal of the motor MY; the first anode A1 terminal of the first bidirectional thyristor T1 is connected to the second anode A2 terminal of the second bidirectional thyristor T2; the trigger terminal G terminal of the first bidirectional thyristor T1 is connected to one end of the first positive temperature coefficient thermistor PTC1; the first anode A1 terminal of the second bidirectional thyristor T2 is connected to the main winding M terminal and the AC power supply N terminal of the motor MY; the trigger terminal G terminal of the second bidirectional thyristor T2 is connected to one end of the second positive temperature coefficient thermistor PTC2; the other end of the first positive temperature coefficient thermistor PTC1 is connected to the other end of the second positive temperature coefficient thermistor PTC2, and both are connected to the C terminal and the AC power supply L terminal of the motor MY. Figure 13 As shown.

[0063] Specifically, when the motor starts, both the first positive temperature coefficient thermistor PTC1 and the second positive temperature coefficient thermistor PTC2 are in a cold, low-resistance state. The trigger circuit current of the second bidirectional thyristor T2, which is connected in series with the second positive temperature coefficient thermistor PTC2, is relatively large. At the same time, the AC power supply forms a terminal voltage through the first positive temperature coefficient thermistor PTC1, the trigger terminal G of the first bidirectional thyristor T1, and the first anode A1 terminal between the first anode A1 and the second anode A2 terminals of the second bidirectional thyristor T2, and the second bidirectional thyristor T2 is turned on. As the second bidirectional thyristor T2 is turned on, the trigger circuit of the first bidirectional thyristor T1, which is connected in series with the first positive temperature coefficient thermistor PTC1, is triggered. A large current is generated in the circuit, and a terminal voltage is also formed between the first anode A1 terminal and the second anode A2 terminal of the first bidirectional thyristor T1. The first bidirectional thyristor T1 is also turned on. With the simultaneous turn-on of the first bidirectional thyristor T1 and the second bidirectional thyristor T2, the motor starting circuit is connected, and the motor starts normally. During the starting process, the resistance values ​​of the first positive temperature coefficient thermistor PTC1 and the second positive temperature coefficient thermistor PTC2 tend to the maximum value under the action of R / T characteristics, and the corresponding trigger current decreases. When the triggering turn-on condition cannot be met, the first bidirectional thyristor T1 and the second bidirectional thyristor T2 are turned off at the AC zero crossing, and the motor starting process ends.

[0064] More specifically, such as Figure 1 , 4The working principle is as follows: According to the starting principle of the motor, when the power is applied, the starter first connects the auxiliary winding circuit (motor starting circuit), and then disconnects the auxiliary winding circuit after the start is completed. In the motor starter control circuit of this dual-switch mode, this process is realized by the opening and closing of two bidirectional thyristors. The two conditions for the bidirectional thyristor to conduct are: first, there is sufficient trigger current at the trigger electrode G terminal; second, there is a certain terminal voltage between the first anode A1 terminal and the second anode A2 terminal.

[0065] When the motor is powered on, both the first bidirectional thyristor T1 and the second bidirectional thyristor T2 are in the off state, the secondary winding circuit is not conducting, and the main winding circuit (motor running circuit) formed by the AC power supply L terminal → main winding → primary coil P → AC power supply N terminal is conducting. At this time, the motor is in a stalled state, the main winding circuit current is large, and the primary coil P current is also large. Through electromagnetic induction, the induced currents of secondary coil one K1 and secondary coil two K2 are also large, so that the triggering poles G terminals of the first bidirectional thyristor T1 and the second bidirectional thyristor T2 receive a sufficiently large triggering current, and the triggering condition for the two bidirectional thyristors to conduct is met; the first anode A1 terminal of the first bidirectional thyristor T1 - the second anode terminal... The A2 terminal is first turned on by obtaining the terminal voltage through the secondary winding and the high-resistivity resistor R. As the first bidirectional thyristor T1 turns on, the first anode A1 terminal and the second anode A2 terminal of the second bidirectional thyristor T2 also obtain the terminal voltage and then turn on. After the two bidirectional thyristors turn on simultaneously, the secondary winding circuit is connected, and the motor starts. After the motor starts and runs normally, the current of the primary coil P connected in series in the main winding circuit decreases, and the induced current of the secondary coil K1 and the secondary coil K2 also decreases accordingly. When the current decreases to the point where the conduction trigger condition cannot be met, the first bidirectional thyristor T1 and the second bidirectional thyristor T2 will turn off at the zero-crossing point of the AC voltage, and the entire starting process ends.

[0066] like Figure 2 , 5 As shown, its working principle is the same as Figure 1 , 4 In comparison, the turn-on sequence of the two bidirectional thyristors differs. Due to the different connection methods of the high-resistivity resistor R, when the motor starts, the first anode A1 terminal to the second anode A2 terminal of the second bidirectional thyristor T2 obtains the terminal voltage through the auxiliary winding and the high-resistivity resistor R and is turned on first. As the second bidirectional thyristor T2 is turned on, the first anode A1 terminal to the second anode A2 terminal of the first bidirectional thyristor T1 also obtains the terminal voltage and is then turned on, thus realizing the start-up of the motor.

[0067] like Figure 3 , 6 As shown, its working principle is the same as Figure 1 , 4In comparison, the turn-on sequence of the two bidirectional thyristors differs. Due to the different connection methods of the high-resistivity resistor R, when the motor starts, the first anode A1 terminal to the second anode A2 terminal of the second bidirectional thyristor T2 obtains the terminal voltage through the high-resistivity resistor R and is turned on first. As the second bidirectional thyristor T2 is turned on, the first anode A1 terminal to the second anode A2 terminal of the first bidirectional thyristor T1 also obtains the terminal voltage and is then turned on, thus realizing the start-up of the motor.

[0068] like Figure 7 , 10 The working principle is as follows: After the AC power supply is connected at terminals L and N, the secondary winding circuit is not conductive because both the first bidirectional thyristor T1 and the second bidirectional thyristor T2 are in the off state. The main winding circuit, formed by AC power supply L terminal → main winding → primary coil P → AC power supply N terminal, is conductive. Since the motor is in a stalled state at this time, the current in the primary coil P connected in series with the main winding is large. Through electromagnetic induction, the secondary coil K1 senses a sufficiently large trigger current, satisfying the triggering condition for the first bidirectional thyristor T1 to conduct. The triggering circuit for the second bidirectional thyristor T2 is formed by AC power supply L terminal → first positive temperature coefficient thermistor PTC1 → trigger electrode G terminal of the second bidirectional thyristor T2 → first anode A1 terminal → AC power supply N terminal. Because the resistance of the first positive temperature coefficient thermistor PTC1 is small in the cold state, the trigger current is large, thus the second bidirectional thyristor T2 conducts. The triggering conditions are also met; the first bidirectional thyristor T1 is turned on first by obtaining the terminal voltage at the first anode A1 terminal to the second anode A2 terminal through the secondary winding and the high-resistivity resistor R. The conduction of the first bidirectional thyristor T1 causes the first anode A1 terminal to the second anode A2 terminal of the second bidirectional thyristor T2 to also obtain the terminal voltage and then turn on. After the two bidirectional thyristors are turned on at the same time, the secondary winding circuit is connected, and the motor starts. After the motor starts and runs normally, the current of the primary coil P connected in series in the main winding circuit decreases, and the induced current of the secondary coil K1 also decreases accordingly. The triggering current of the second bidirectional thyristor T2 also decreases due to the R / T characteristic of the first positive temperature coefficient thermistor PTC1. When it decreases to the point where the triggering conditions cannot be met, the first bidirectional thyristor T1 and the second bidirectional thyristor T2 will be turned off at the zero-crossing point of the AC voltage, and the entire starting process ends.

[0069] like Figure 8 , 11 As shown, its working principle is the same as Figure 7 , 10In comparison, the turn-on sequence of the two bidirectional thyristors differs. Due to the different connection methods of the high-resistivity resistor R, when the motor starts, the first anode A1 terminal to the second anode A2 terminal of the second bidirectional thyristor T2 obtains the terminal voltage through the auxiliary winding and the high-resistivity resistor R and is turned on first. As the second bidirectional thyristor T2 is turned on, the first anode A1 terminal to the second anode A2 terminal of the first bidirectional thyristor T1 also obtains the terminal voltage and is then turned on, thus realizing the start-up of the motor.

[0070] like Figure 9 , 12 As shown, its working principle is the same as Figure 7 , 10 In comparison, the turn-on sequence of the two bidirectional thyristors differs. Due to the different connection methods of the high-resistivity resistor R, when the motor starts, the first anode A1 terminal to the second anode A2 terminal of the second bidirectional thyristor T2 obtains the terminal voltage through the high-resistivity resistor R and is turned on first. As the second bidirectional thyristor T2 is turned on, the first bidirectional thyristor T1 also obtains the terminal voltage and is then turned on, thus realizing the start-up of the motor.

[0071] like Figure 13 The working principle is as follows: After the AC power supply is connected at terminals L and N, since both the first bidirectional thyristor T1 and the second bidirectional thyristor T2 are in the off state, the secondary winding circuit is not conductive; the AC power supply L terminal → the second positive temperature coefficient thermistor PTC2 → the trigger terminal G of the second bidirectional thyristor T2 - the first anode A1 terminal → the AC power supply N terminal forms the trigger circuit for the second bidirectional thyristor T2. Since the resistance of the second positive temperature coefficient thermistor PTC2 is small when cold, the trigger current is large, so the triggering condition for the second bidirectional thyristor T2 to conduct is met; at the same time, the first anode A1 terminal of the second bidirectional thyristor T2... The first bidirectional thyristor (SCR) connects to the second anode (A2) via a voltage obtained from the first positive temperature coefficient thermistor (PTC1) and the trigger terminal (G) of the first bidirectional thyristor (T1) at the first anode (A1). The conduction of the second bidirectional thyristor (T2) then allows the first bidirectional thyristor (T1) to obtain a voltage across its terminals. Simultaneously, the cold-state PTC1 generates a large trigger current at its trigger terminal (G). Once the two conditions for T1's conduction are met, it also conducts. With both thyristors conducting simultaneously, the secondary winding circuit is connected, and the motor begins its starting process. After the motor has started and is running normally, the trigger currents of the first bidirectional thyristor (T1) and the second bidirectional thyristor (T2) decrease due to the R / T characteristics of their respective PTC thermistors. When the current decreases to the point where the trigger conditions are no longer met, both T1 and T2 will turn off at the zero-crossing point of the AC voltage, thus ending the entire starting process.

[0072] In all the above schemes, when one of the two bidirectional thyristors is short-circuited, the motor starting function can still be achieved by controlling the on / off state of the other bidirectional thyristor. The specific analysis is as follows: When a short circuit occurs between the first anode A1 terminal and the second anode A2 terminal of either the first bidirectional thyristor T1 or the second bidirectional thyristor T2, the starter is not short-circuited because either the second bidirectional thyristor T2 or the first bidirectional thyristor T1 is in a normally off state. According to the previous analysis, at the start of motor starting, both bidirectional thyristors have sufficient trigger current at their trigger terminals G. The short circuit between the first anode A1 terminal and the second anode A2 terminal of the first bidirectional thyristor T1 will affect the motor starting function at the first anode A1 terminal of the second bidirectional thyristor T2. A certain terminal voltage is formed between the second anode A2 terminals, so the second bidirectional thyristor T2 is triggered to conduct; similarly, a short circuit between the first anode A1 terminal and the second anode A2 terminal of the second bidirectional thyristor T2 will form a certain terminal voltage between the first anode A1 terminal and the second anode A2 terminal of the first bidirectional thyristor T1, so the first bidirectional thyristor T1 is triggered to conduct; both situations can connect the secondary winding circuit and execute the starting process; after the start is completed, the trigger current decreases, and the secondary winding circuit can still be turned off through the non-short-circuited bidirectional thyristor.

[0073] Furthermore, it should be noted that the specific embodiments described in this specification may differ in the shape and name of their components. The above description is merely illustrative of the structure of this utility model. All equivalent or simple variations made based on the structure, features, and principles described in this utility model are included within the protection scope of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the structure of this utility model or exceed the scope defined by the claims, all of which should fall within the protection scope of this utility model.

Claims

1. A dual-switch mode motor starter control circuit, comprising a current transformer (CT), a first bidirectional thyristor (T1), and a second bidirectional thyristor (T2), wherein the current transformer (CT) is designed with a primary coil (P), a first secondary coil (K1), and a second secondary coil (K2), the primary coil (P) being connected in series with the main winding of a motor (MY) to form a motor operating circuit, and the first bidirectional thyristor (T1) and the second bidirectional thyristor (T2) being connected in series with the auxiliary winding of the motor (MY) to form a motor starting circuit, characterized in that: It also includes a high-resistivity resistor (R), which is connected to the motor starting circuit. The trigger terminals G of the first bidirectional thyristor (T1) and the second bidirectional thyristor (T2) are connected in series with the second secondary coil (K1) and the second secondary coil (K2), respectively. The first bidirectional thyristor (T1) and the second bidirectional thyristor (T2) are turned on and off by sensing the current change in the motor running circuit.

2. The motor starter control circuit with dual-switch mode according to claim 1, characterized in that: The primary coil (P) is connected to the main winding M of the motor (MY) at terminal 1. The secondary coil (K1) is connected to the first anode A1 of the first bidirectional thyristor (T1) and the auxiliary winding S of the motor (MY) at terminal 3. The secondary coil (K1) is connected to the trigger G of the first bidirectional thyristor (T1) at terminal 4. The secondary coil (K2) is connected to the second anode A2 of the first bidirectional thyristor (T1), the first anode A1 of the second bidirectional thyristor (T2), and one end of the high-resistivity resistor (R) at terminal 5. The secondary coil (K2) is connected to the trigger G of the second bidirectional thyristor (T2) at terminal 6. The second anode A2 of the second bidirectional thyristor (T2) is connected to the primary coil (P) at terminal 2, the other end of the high-resistivity resistor (R), and the AC power supply N at terminal 6. The motor (MY) is connected to the AC power supply L at terminal 7.

3. The motor starter control circuit with dual-switch mode according to claim 1, characterized in that: The primary coil (P) is connected to the main winding M of the motor (MY) at terminal 1. The secondary coil (K1) is connected to the first anode A1 of the first bidirectional thyristor (T1), one end of the high-resistivity resistor (R), and the secondary winding S of the motor (MY) at terminal 3. The secondary coil (K1) is connected to the trigger G of the first bidirectional thyristor (T1) at terminal 4. The secondary coil (K2) is connected to the second anode A2 of the first bidirectional thyristor (T1), the first anode A1 of the second bidirectional thyristor (T2), and the other end of the high-resistivity resistor (R) at terminal 5. The secondary coil (K2) is connected to the trigger G of the second bidirectional thyristor (T2) at terminal 6. The second anode A2 of the second bidirectional thyristor (T2) is connected to the primary coil (P) at terminal 2 and the AC power supply N at terminal 3. The motor (MY) is connected to the AC power supply L at terminal 4.

4. The motor starter control circuit with dual-switch mode according to claim 1, characterized in that: One end of the primary coil (P) is connected to the main winding M end of the motor (MY). The three ends of the secondary coil one (K1) are connected to the first anode A1 end of the first bidirectional thyristor (T1) and the auxiliary winding S end of the motor (MY). The four ends of the secondary coil one (K1) are connected to the trigger G end of the first bidirectional thyristor (T1). The five ends of the secondary coil two (K2) are connected to the second anode A2 end of the first bidirectional thyristor (T1), the first anode A1 end of the second bidirectional thyristor (T2), and one end of the high-resistivity resistor (R). The six ends of the secondary coil two (K2) are connected to the trigger G end of the second bidirectional thyristor (T2). The second anode A2 end of the second bidirectional thyristor (T2) is connected to the two ends of the primary coil (P) and the AC power supply N end. The other end of the high-resistivity resistor (R) is connected to the C end of the motor (MY) and the AC power supply L end.

5. The motor starter control circuit with dual-switch mode according to claim 1, characterized in that: The primary coil (P) is connected to the main winding (M) of the motor (MY) at terminal 1. The secondary coil (K1) is connected to the trigger electrode (G) of the first bidirectional thyristor (T1) at terminal 3. The secondary coil (K1) is connected to the first anode (A1) of the first bidirectional thyristor (T1), the second anode (A2) of the second bidirectional thyristor (T2), and one end of the high-resistivity resistor (R) at terminal 4. The secondary coil (K2) is connected to the trigger electrode (G) of the second bidirectional thyristor (T2) at terminal 5. The secondary coil (K2) is connected to the first anode (A1) of the second bidirectional thyristor (T2), terminal 2 of the primary coil (P), the other end of the high-resistivity resistor (R), and the AC power supply (N) at terminal 6. The first bidirectional thyristor (T1) is connected to the auxiliary winding (S) of the motor (MY). The motor (MY) is connected to the AC power supply (L) at terminal 7.

6. The motor starter control circuit with dual-switch mode according to claim 1, characterized in that: The primary coil (P) is connected to the main winding (M) of the motor (MY) at terminal 1. The secondary coil (K1) is connected to the trigger terminal (G) of the first bidirectional thyristor (T1) at terminal 3. The secondary coil (K1) is connected to the first anode (A1) of the first bidirectional thyristor (T1), the second anode (A2) of the second bidirectional thyristor (T2), and one end of the high-resistivity resistor (R) at terminal 4. The secondary coil (K2) is connected to the trigger terminal (G) of the second bidirectional thyristor (T2) at terminal 5. The secondary coil (K2) is connected to the first anode (A1) of the second bidirectional thyristor (T2), terminal 2 of the primary coil (P) at terminal 2, and the AC power supply (N) at terminal 6. The first bidirectional thyristor (T1) is connected to the other end of the high-resistivity resistor (R) and the secondary winding (S) of the motor (MY) at terminal 7. The motor (MY) is connected to the AC power supply (L) at terminal 8.

7. The motor starter control circuit with dual-switch mode according to claim 1, characterized in that: The primary coil (P) is connected to the main winding (M) of the motor (MY) at terminal 1. The secondary coil (K1) is connected to the trigger terminal (G) of the first bidirectional thyristor (T1) at terminal 3. The secondary coil (K1) is connected to the first anode (A1) of the first bidirectional thyristor (T1), the second anode (A2) of the second bidirectional thyristor (T2), and one end of the high-resistivity resistor (R) at terminal 4. The secondary coil (K2) is connected to the trigger terminal (G) of the second bidirectional thyristor (T2) at terminal 5. The secondary coil (K2) is connected to the first anode (A1) of the second bidirectional thyristor (T2), terminal 2 of the primary coil (P), and the AC power supply (N) at terminal 6. The first bidirectional thyristor (T1) is connected to the auxiliary winding (S) of the motor (MY) at terminal 5. The high-resistivity resistor (R) is connected to the motor (MY) at terminal C and the AC power supply (L) at terminal 6.

8. A dual-switch mode motor starter control circuit, comprising a current transformer (CT), a first bidirectional thyristor (T1), a second bidirectional thyristor (T2), and a first positive temperature coefficient thermistor (PTC1), wherein the current transformer (CT) is designed with a primary coil (P) and a secondary coil (K1), the primary coil (P) being connected in series with the main winding of a motor (MY) to form a motor operating circuit, and the first bidirectional thyristor (T1) and the second bidirectional thyristor (T2) being connected in series with the secondary winding of the motor (MY) to form a motor starting circuit, characterized in that: It also includes a high-resistivity resistor (R), which is connected to the motor starting circuit. The trigger terminal G of the first bidirectional thyristor (T1) is connected in series with the secondary coil (K1). The switching on and off of the first bidirectional thyristor (T1) is controlled by the current change in the motor running circuit. The trigger terminal G of the second bidirectional thyristor (T2) is connected in series with the first positive temperature coefficient thermistor (PTC1). The switching on and off of the second bidirectional thyristor (T2) is controlled by the R / T characteristic of the first positive temperature coefficient thermistor (PTC1).

9. The motor starter control circuit with dual-switch mode according to claim 8, characterized in that: One end of the primary coil (P) is connected to the main winding M end of the motor (MY). The three ends of the secondary coil (K1) are connected to the first anode A1 end of the first bidirectional thyristor (T1) and the auxiliary winding S end of the motor (MY). The four ends of the secondary coil (K1) are connected to the trigger G end of the first bidirectional thyristor (T1). The second anode A2 end of the first bidirectional thyristor (T1) is connected to the second anode A2 end of the second bidirectional thyristor (T2) and one end of the high-resistivity resistor (R). The trigger G end of the second bidirectional thyristor (T2) is connected to one end of the first positive temperature coefficient thermistor (PTC1). The other end of the first positive temperature coefficient thermistor (PTC1) is connected to the C end of the motor (MY) and the AC power supply L end. The first anode A1 end of the second bidirectional thyristor (T2) is connected to the two ends of the primary coil (P), the other end of the high-resistivity resistor (R), and the AC power supply N end.

10. The motor starter control circuit with dual-switch mode according to claim 8, characterized in that: One end of the primary coil (P) is connected to the main winding M end of the motor (MY). The three ends of the secondary coil (K1) are connected to one end of the high-resistivity resistor (R), the first anode A1 end of the first bidirectional thyristor (T1), and the auxiliary winding S end of the motor (MY). The four ends of the secondary coil (K1) are connected to the trigger G end of the first bidirectional thyristor (T1). The second anode A2 end of the first bidirectional thyristor (T1) is connected to the second anode A2 end of the second bidirectional thyristor (T2) and the other end of the high-resistivity resistor (R). The trigger G end of the second bidirectional thyristor (T2) is connected to one end of the first positive temperature coefficient thermistor (PTC1). The other end of the first positive temperature coefficient thermistor (PTC1) is connected to the C end of the motor (MY) and the AC power supply L end. The first anode A1 end of the second bidirectional thyristor (T2) is connected to the two ends of the primary coil (P) and the AC power supply N end.

11. The motor starter control circuit with dual-switch mode according to claim 8, characterized in that: One end of the primary coil (P) is connected to the main winding M end of the motor (MY). The three ends of the secondary coil (K1) are connected to the first anode A1 end of the first bidirectional thyristor (T1) and the auxiliary winding S end of the motor (MY). The four ends of the secondary coil (K1) are connected to the trigger G end of the first bidirectional thyristor (T1). The second anode A2 end of the first bidirectional thyristor (T1) is connected to the second anode A2 end of the second bidirectional thyristor (T2) and one end of the high-resistivity resistor (R). The trigger G end of the second bidirectional thyristor (T2) is connected to one end of the first positive temperature coefficient thermistor (PTC1). The other end of the first positive temperature coefficient thermistor (PTC1) is connected to the other end of the high-resistivity resistor (R), the C end of the motor (MY), and the L end of the AC power supply. The first anode A1 end of the second bidirectional thyristor (T2) is connected to the two ends of the primary coil (P) and the N end of the AC power supply.

12. The motor starter control circuit with dual-switch mode according to claim 8, characterized in that: One end of the primary coil (P) is connected to the M end of the main winding of the motor (MY). The 3rd end of the secondary coil (K1) is connected to the G end of the trigger electrode of the first bidirectional thyristor (T1). The 4th end of the secondary coil (K1) is connected to the first anode A1 end of the first bidirectional thyristor (T1), the second anode A2 end of the second bidirectional thyristor (T2), and one end of the high-resistivity resistor (R). The second anode A2 end of the first bidirectional thyristor (T1) is connected to the S end of the auxiliary winding of the motor (MY). The G end of the trigger electrode of the second bidirectional thyristor (T2) is connected to one end of the first positive temperature coefficient thermistor (PTC1). The other end of the first positive temperature coefficient thermistor (PTC1) is connected to the C end of the motor (MY) and the L end of the AC power supply. The first anode A1 end of the second bidirectional thyristor (T2) is connected to the 2nd end of the primary coil (P), the other end of the high-resistivity resistor (R), and the N end of the AC power supply.

13. The dual-switch mode motor starter control circuit according to claim 8, characterized in that: The primary coil (P) is connected to the main winding (M) of the motor (MY) at one end. The secondary coil (K1) is connected to the trigger terminal (G) of the first bidirectional thyristor (T1). The secondary coil (K1) is connected to the first anode (A1) of the first bidirectional thyristor (T1), the second anode (A2) of the second bidirectional thyristor (T2), and one end of the high-resistivity resistor (R). The second anode (A2) of the first bidirectional thyristor (T1) is connected to the other end of the high-resistivity resistor (R) and the auxiliary winding (S) of the motor (MY). The trigger terminal (G) of the second bidirectional thyristor (T2) is connected to one end of the first positive temperature coefficient thermistor (PTC1). The other end of the first positive temperature coefficient thermistor (PTC1) is connected to the motor (MY) at one end and the AC power supply at one end. The first anode (A1) of the second bidirectional thyristor (T2) is connected to the primary coil (P) at one end and the AC power supply at one end.

14. The dual-switch mode motor starter control circuit according to claim 8, characterized in that: One end of the primary coil (P) is connected to the main winding M end of the motor (MY). The third end of the secondary coil (K1) is connected to the trigger G end of the first bidirectional thyristor (T1). The fourth end of the secondary coil (K1) is connected to the first anode A1 end of the first bidirectional thyristor (T1), the second anode A2 end of the second bidirectional thyristor (T2), and one end of the high-resistivity resistor (R). The second anode A2 end of the first bidirectional thyristor (T1) is connected to the auxiliary winding S end of the motor (MY). The trigger G end of the second bidirectional thyristor (T2) is connected to one end of the first positive temperature coefficient thermistor (PTC1). The other end of the first positive temperature coefficient thermistor (PTC1) is connected to the other end of the high-resistivity resistor (R), the C end of the motor (MY), and the L end of the AC power supply. The first anode A1 end of the second bidirectional thyristor (T2) is connected to the second end of the primary coil (P) and the N end of the AC power supply.

15. A dual-switch mode motor starter control circuit, comprising a first bidirectional thyristor (T1), a second bidirectional thyristor (T2), a first positive temperature coefficient thermistor (PTC1), and a second positive temperature coefficient thermistor (PTC2), characterized in that: The second anode A2 terminal of the first bidirectional thyristor (T1) is connected to the auxiliary winding S terminal of the motor (MY). The first anode A1 terminal of the first bidirectional thyristor (T1) is connected to the second anode A2 terminal of the second bidirectional thyristor (T2). The trigger terminal G terminal of the first bidirectional thyristor (T1) is connected to one end of the first positive temperature coefficient thermistor (PTC1). The first anode A1 terminal of the second bidirectional thyristor (T2) is connected to the main winding M terminal and the AC power supply N terminal of the motor (MY). The trigger terminal G terminal of the second bidirectional thyristor (T2) is connected to one end of the second positive temperature coefficient thermistor (PTC2). The other end of the first positive temperature coefficient thermistor (PTC1) is connected to the other end of the second positive temperature coefficient thermistor (PTC2), and both are connected to the C terminal and the AC power supply L terminal of the motor (MY).

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