Speed regulation circuit and speed regulation system of alternating current motor

Abstract

The utility model provides a speed regulation circuit and a speed regulation system of an AC motor. The speed regulation circuit comprises a voltage regulation circuit, a voltage stabilizing circuit and a speed regulation device. One end of the voltage regulating circuit is connected with the alternating current motor; one end of the voltage stabilizing circuit is connected with the other end of the voltage regulating circuit, and the other end of the voltage stabilizing circuit is connected with a power supply; one end of the speed regulating device is respectively connected with the other end of the voltage stabilizing circuit and the power supply, the other end of the speed regulating device is connected with the alternating current motor, and the voltage regulating value of the voltage stabilizing circuit is regulated by regulating the voltage regulating value of the voltage regulating circuit so as to control the speed regulating device to regulate the rotating speed of the alternating current motor. According to the utility model, smooth speed regulation can be carried out on the AC motor, and the cost is low.

Description

Technical Field

[0001] The utility model relates to the technical field of AC motors, in particular to a speed regulating circuit and a speed regulating system of an AC motor. Background Art

[0002] When AC motors are used in practice, they need to be regulated due to functional limitations of the products they are adapted to or restrictions on energy consumption standards. The main speed regulation methods currently used either require the use of a frequency converter, which results in high costs, or use stepped speed regulation, which has a large span between levels and cannot be smoothly regulated. Utility Model Content

[0003] The utility model provides a speed regulation circuit and a speed regulation system for an AC motor, aiming to solve the problem that the current speed regulation method for the AC motor has high cost and cannot smoothly regulate the speed.

[0004] In a first aspect, the utility model provides a speed regulation circuit for an AC motor, comprising a voltage regulating circuit, a voltage stabilizing circuit and a speed regulating device; one end of the voltage regulating circuit is connected to the AC motor; one end of the voltage stabilizing circuit is connected to the other end of the voltage regulating circuit, and the other end of the voltage stabilizing circuit is connected to a power supply; one end of the speed regulating device is respectively connected to the other end of the voltage stabilizing circuit and the power supply, and the other end of the speed regulating device is connected to the AC motor; wherein, the voltage stabilizing value of the voltage stabilizing circuit is adjusted by adjusting the voltage regulating value of the voltage regulating circuit to control the speed regulating device to adjust the speed of the AC motor.

[0005] Furthermore, the speed regulating device is a bidirectional thyristor, a controlled end of the bidirectional thyristor is connected to the voltage stabilizing circuit, an input end of the bidirectional thyristor is connected to the power supply, and an output end of the bidirectional thyristor is connected to the AC motor.

[0006] Furthermore, the voltage regulating circuit includes a first adjustable resistor, one end of the first adjustable resistor is connected to the AC motor, and the other end of the first adjustable resistor is connected to the voltage stabilizing circuit.

[0007] Furthermore, the voltage regulating circuit also includes a first resistor, one end of the first resistor is connected to the AC motor, and the other end of the first resistor is connected to the first adjustable resistor.

[0008] Furthermore, the voltage stabilizing circuit includes a bidirectional diode, one end of the bidirectional diode is connected to the power supply, and the other end of the bidirectional diode is connected to the speed regulating device.

[0009] Furthermore, the voltage stabilizing circuit also includes a first capacitor, one end of which is connected to the power supply, and the other end of which is respectively connected to the speed regulating circuit and the bidirectional diode.

[0010] Furthermore, it also includes a protection circuit, one end of which is connected to the power supply, and the other end of which is connected to the voltage stabilizing circuit and the speed regulating device respectively.

[0011] Furthermore, the protection circuit includes a second resistor, one end of the second resistor is connected to the power supply, and the other end of the second resistor is connected to the voltage stabilizing circuit and the speed regulating device respectively.

[0012] Furthermore, it also includes a second capacitor, which is connected between the main phase winding and the auxiliary phase winding of the AC motor.

[0013] In a second aspect, the utility model provides a speed regulation system for an AC motor, the speed regulation system for the AC motor comprising a power supply and a speed regulation circuit for the AC motor as described above; the power supply is respectively connected to a voltage stabilizing circuit and a speed regulation device of the speed regulation circuit of the AC motor.

[0014] The speed regulation system of an AC motor disclosed in the utility model comprises a speed regulation circuit of the AC motor, wherein the speed regulation circuit comprises a voltage regulation circuit, a voltage stabilizing circuit and a speed regulation device, wherein the voltage stabilizing circuit is respectively connected to a power supply, the voltage regulation circuit and the speed regulation device, and the speed regulation device and the voltage regulation circuit are also connected to the AC motor, wherein the voltage regulation circuit can adjust a voltage stabilizing value of the voltage stabilizing circuit, and the speed regulation device can adjust the rotational speed of the AC motor, and the speed regulation of the speed regulation device is related to the voltage stabilizing value of the voltage stabilizing circuit, and the voltage stabilizing value can be changed by changing the voltage regulation value of the voltage regulation circuit, thereby changing the rotational speed of the motor, thereby achieving smooth speed regulation and having a low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a block diagram of a speed control circuit of an AC motor provided by an embodiment of the utility model;

[0017] Figure 2 It is a circuit diagram of a speed regulating circuit of an AC motor provided by an embodiment of the utility model;

[0018] Figure 3It is a block diagram of a speed regulating circuit of an AC motor provided by another embodiment of the utility model;

[0019] Figure 4 is a circuit diagram of a speed regulating circuit of an AC motor provided by another embodiment of the utility model;

[0020] Figure 5 It is a voltage waveform diagram of the AC motor winding provided by an embodiment of the utility model;

[0021] Figure 6 This is an internal structure diagram of a unidirectional thyristor provided in one embodiment of the utility model;

[0022] Figure 7 It is an internal structure diagram of a bidirectional thyristor provided in one embodiment of the utility model. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0024] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, operations, elements, components and / or groups thereof.

[0025] It should also be understood that the terms used in this utility model specification are only for the purpose of describing specific embodiments and are not intended to limit the utility model. As used in the utility model specification and the appended claims, the singular forms of "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" used in the utility model specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0026] In addition, the directional terms mentioned in the present invention, such as "upper", "lower", "front", "back", "left", "right", "inner", "outer", "side", etc., are only for reference to the directions of the attached drawings and the use status of the product. Therefore, the directional terms used are used to illustrate and understand the present invention, but not to limit the present invention. In addition, in the drawings, structures with similar or identical structures are represented by the same reference numerals.

[0027] See also Figures 1 to 7 , Figure 1 1 is a block diagram of a speed control circuit 100 for an AC motor provided by an embodiment of the present utility model; Figure 2 1 is a circuit diagram of a speed control circuit 100 for an AC motor provided in one embodiment of the utility model; Figure 3 1 is a block diagram of a speed control circuit 100 for an AC motor provided by another embodiment of the present utility model; Figure 4 is a circuit diagram of a speed control circuit 100 for an AC motor provided by another embodiment of the utility model; Figure 5 It is a voltage waveform diagram of the AC motor winding provided by an embodiment of the utility model; Figure 6 This is an internal structure diagram of a unidirectional thyristor provided in one embodiment of the utility model; Figure 7 It is an internal structure diagram of a bidirectional thyristor VS provided in one embodiment of the utility model.

[0028] like Figure 1 As shown, the speed regulation circuit 100 of the AC motor includes a voltage regulating circuit 10, a voltage stabilizing circuit 20 and a speed regulating device 30; one end of the voltage regulating circuit 10 is connected to the AC motor 300; one end of the voltage stabilizing circuit 20 is connected to the other end of the voltage regulating circuit 10, and the other end of the voltage stabilizing circuit 20 is connected to the power supply 200; one end of the speed regulating device 30 is respectively connected to the other end of the voltage stabilizing circuit 20 and the power supply 200, and the other end of the speed regulating device 30 is connected to the AC motor 300, wherein the voltage stabilizing value of the voltage stabilizing circuit 20 is adjusted by adjusting the voltage regulating value of the voltage regulating circuit 10 to control the speed regulating device 30 to adjust the speed of the AC motor 300.

[0029] Specifically, the speed regulating circuit 100 of the AC motor includes a voltage regulating circuit 10, a voltage stabilizing circuit 20, and a speed regulating device 30. One end of the voltage regulating circuit 10 is connected to the AC motor 300, and the effective value of the terminal voltage loaded on the AC motor winding can be adjusted. The other end of the voltage regulating circuit 10 is connected to the voltage stabilizing circuit 20. The voltage regulating circuit 10 may include multiple resistors and at least one adjustable resistor. The multiple resistors and the adjustable resistor are connected in series with each other. The voltage of the voltage regulating circuit 10 can be adjusted by changing the resistance value of the adjustable resistor to change the voltage regulation value.

[0030] One end of the voltage stabilizing circuit 20 is connected to the power supply 200, and the other end of the voltage stabilizing circuit 20 is connected to the speed regulating device 30. At the same time, the voltage stabilizing circuit 20 is also connected to the voltage regulating circuit 10. The voltage stabilizing circuit 20 may include a diode, which has a voltage stabilizing value, and the voltage stabilizing value is adjusted by the voltage regulating value of the voltage regulating circuit 10. Preferably, the voltage stabilizing circuit 20 may include a bidirectional diode VD. In addition, the power supply 200 may be an AC power supply for powering the AC motor 300.

[0031] One end of the speed regulating device 30 is connected to the voltage stabilizing circuit 20, and the other end of the speed regulating device 30 is connected to the AC motor 300, for adjusting the speed of the AC motor 300. The speed regulating device 30 may be a bidirectional thyristor VS, and the bidirectional thyristor VS has a conduction angle α, and the angle of the conduction angle α is related to the voltage stabilizing value of the voltage stabilizing circuit 20. At the same time, the conduction angle α is related to the voltage waveform of the AC motor 300, and can change the effective value of the terminal voltage of the AC motor 300, thereby smoothly adjusting the speed of the AC motor 300.

[0032] When in use, the voltage regulation value of the voltage regulating circuit 10 can be adjusted to adjust the voltage regulation value of the voltage stabilizing circuit 20 , and then the conduction angle α of the speed regulating device 30 can be adjusted, thereby achieving speed regulation of the AC motor 300 .

[0033] When the voltage regulation value changes, the voltage stabilization value also changes, causing the conduction angle α of the bidirectional thyristor VS to change. The conduction angle α is related to the actual voltage applied to the AC motor winding, thereby affecting the speed of the AC motor 300. Figure 5 As shown, when the conduction angle α is larger, the actual voltage applied to the AC motor winding is larger. Since the bidirectional thyristor VS includes two unidirectional thyristors, smooth speed regulation can be achieved.

[0034] See also Figure 2 As a further embodiment, the speed regulating device 30 is a bidirectional thyristor VS, the controlled end of the bidirectional thyristor VS is connected to the voltage stabilizing circuit 20, the input end of the bidirectional thyristor VS is connected to the power supply 200, and the output end of the bidirectional thyristor VS is connected to the AC motor 300.

[0035] Among them, Figure 2 As shown, the speed regulating device 30 can be a bidirectional thyristor VS, the controlled end of the bidirectional thyristor VS is connected to the voltage stabilizing circuit 20, the input end of the bidirectional thyristor VS is connected to the power supply 200, and the output end of the bidirectional thyristor VS is connected to the AC motor 300.

[0036] When the voltage regulation value of the voltage regulating circuit 10 changes, the voltage regulation value of the voltage stabilizing circuit 20 changes accordingly. At the same time, the conduction angle α of the bidirectional thyristor VS also changes accordingly, thereby changing the effective value of the terminal voltage of the AC motor 300, thereby adjusting the speed of the AC motor 300.

[0037] The interior of a bidirectional thyristor (VS) may include two unidirectional thyristors. The unidirectional thyristor is a semiconductor device composed of four layers of P-type and N-type semiconductor materials. When the unidirectional thyristor is working, its controlled end needs a trigger signal to activate. When the trigger signal is applied to the controlled end of the unidirectional thyristor, the unidirectional thyristor forms a forward voltage, causing the unidirectional thyristor to enter the on state. When the unidirectional thyristor is in the on state, the current in its circuit begins to flow. When the current reaches the specified limit value, that is, when the AC sinusoidal voltage waveform passes through the zero point, the unidirectional thyristor will be closed.

[0038] The bidirectional thyristor VS includes two unidirectional thyristors. When the AC sinusoidal voltage waveform passes through the zero point, the unidirectional thyristor on one side is closed, and the corresponding unidirectional thyristor on the other side that is reversely connected enters the on state, that is, the two unidirectional thyristors in the bidirectional thyristor VS operate alternately, thereby achieving smooth speed regulation of the AC motor 300.

[0039] like Figure 6 As shown, Figure 6 The internal structure diagram of the unidirectional thyristor. Figure 6 The G pole in the middle is the controlled end. When the G pole receives the trigger signal, the unidirectional thyristor is turned on. Figure 7 It is an internal structure diagram of a bidirectional thyristor VS, which includes two unidirectional thyristors. When the unidirectional thyristor on the left is turned off, the unidirectional thyristor on the right is turned on, thereby realizing alternate control of the rotation speed of the AC motor 300.

[0040] As a further embodiment, the voltage regulating circuit 10 includes a first adjustable resistor RP, one end of the first adjustable resistor RP is connected to the AC motor 300 , and the other end of the first adjustable resistor RP is connected to the voltage stabilizing circuit 20 .

[0041] Among them, Figure 2 As shown, the voltage regulating circuit 10 may include a first adjustable resistor RP and at least one series resistor. For example, the voltage regulating circuit 10 may include a first adjustable resistor RP and a series resistor. When there are multiple series resistors, the multiple series resistors are connected in series in sequence.

[0042] The first adjustable resistor RP can adjust its own resistance value to adjust the voltage regulation value of the voltage regulation circuit 10. The first adjustable resistor RP can be any device with adjustable resistance. Preferably, the first adjustable resistor RP is a sliding rheostat. One end of the sliding rheostat is connected to the series resistor, and the other end of the sliding rheostat is connected to the voltage stabilizing circuit 20. The voltage regulation value of the voltage regulation circuit 10 can be changed by changing the resistance value of the sliding rheostat, thereby changing the voltage stabilizing value of the voltage stabilizing circuit 20.

[0043] As a further embodiment, the voltage regulating circuit 10 further includes a first resistor R1 , one end of the first resistor R1 is connected to the AC motor 300 , and the other end of the first resistor R1 is connected to the first adjustable resistor RP.

[0044] The first resistor R1 is used as a series resistor of the first adjustable resistor RP, which is connected in series between the AC motor 300 and the first adjustable resistor RP, that is, one end of the first resistor R1 is connected to the AC motor 300, and the other end of the first resistor R1 is connected to the first adjustable resistor RP.

[0045] As a further embodiment, the voltage stabilizing circuit 20 includes a bidirectional diode VD, one end of the bidirectional diode VD is connected to the power supply 200 , and the other end of the bidirectional diode VD is connected to the speed regulating device 30 .

[0046] The voltage stabilizing circuit 20 may include a bidirectional diode VD, one end of the bidirectional diode VD is connected to the power supply 200, and the other end of the bidirectional diode VD is connected to the speed regulating device 30. The bidirectional diode VD has a voltage stabilizing value, which is related to the voltage regulating value of the voltage regulating circuit 10. When the voltage regulating value of the voltage regulating circuit 10 changes, the voltage stabilizing value of the voltage stabilizing circuit 20 also changes accordingly.

[0047] As a further embodiment, the voltage stabilizing circuit 20 further includes a first capacitor C1, one end of the first capacitor C1 is connected to the power supply 200, and the other end of the first capacitor C1 is respectively connected to the speed regulating circuit and the bidirectional diode VD.

[0048] The voltage stabilizing circuit 20 may further include a first capacitor C1, which is connected to the bidirectional diode VD, and a connection node between the first capacitor C1 and the bidirectional diode VD is also connected to the voltage regulating circuit 10, and the first capacitor C1 is also connected to the power supply 200.

[0049] See also Figure 3 As a further embodiment, it also includes a protection circuit 40, one end of the protection circuit 40 is connected to the power supply 200, and the other end of the protection circuit 40 is connected to the voltage stabilizing circuit 20 and the speed regulating device 30 respectively.

[0050] One end of the protection circuit 40 is connected to the power supply 200, and the other end of the protection circuit 40 is respectively connected to the voltage stabilizing circuit 20 and the speed regulating device 30. The protection circuit 40 is used to provide overcurrent protection for the entire circuit, and may include at least one current limiting resistor, which is connected in series with the power supply 200 to limit the size of the circuit current to avoid circuit damage.

[0051] See also Figure 4As a further embodiment, the protection circuit 40 includes a second resistor R2, one end of the second resistor R2 is connected to the power supply 200, and the other end of the second resistor R2 is connected to the voltage stabilizing circuit 20 and the speed regulating device 30 respectively.

[0052] Among them, Figure 4 As shown, the protection circuit 40 may include a second resistor R2, which is connected in series with the power supply 200, that is, one end of the second resistor R2 is connected to the power supply 200, and the other end of the second resistor R2 is connected to the voltage stabilizing circuit 20 and the speed regulating device 30, respectively, for protecting the voltage stabilizing circuit 20 and the speed regulating device 30.

[0053] As a further embodiment, a second capacitor C2 is further included, and the second capacitor C2 is connected between the main phase winding and the auxiliary phase winding of the AC motor 300.

[0054] Among them, Figure 4 As shown, a second capacitor C2 is connected between the main phase winding and the auxiliary phase winding of the AC motor 300, one end of the second capacitor C2 is connected to the auxiliary phase winding of the AC motor 300, and the other end of the second capacitor C2 is connected to the speed regulating device 30. The second capacitor C2 is used to form a voltage phase difference between the main phase winding and the auxiliary phase winding of the AC motor 300, so as to facilitate the smooth starting and rotation of the AC motor 300.

[0055] The utility model also provides a speed regulation system for an AC motor, the speed regulation system for the AC motor comprising a power supply 200 and a speed regulation circuit 100 for the AC motor described in any one of the above embodiments, the speed regulation circuit 100 for the AC motor comprising a voltage regulating circuit 10, a voltage stabilizing circuit 20 and a speed regulation device 30; one end of the voltage regulating circuit 10 is connected to the AC motor 300; one end of the voltage stabilizing circuit 20 is connected to the other end of the voltage regulating circuit 10, and the other end of the voltage stabilizing circuit 20 is connected to the power supply 200; one end of the speed regulation device 30 is respectively connected to the other end of the voltage stabilizing circuit 20 and the power supply 200, and the other end of the speed regulation device 30 is connected to the AC motor 300, wherein the voltage regulation value of the voltage stabilizing circuit 20 is adjusted by adjusting the voltage regulation value of the voltage regulating circuit 10 to control the speed regulation device 30 to adjust the rotation speed of the AC motor 300.

[0056] Specifically, the speed regulating circuit 100 of the AC motor includes a voltage regulating circuit 10, a voltage stabilizing circuit 20, and a speed regulating device 30. One end of the voltage regulating circuit 10 is connected to the AC motor 300, and the effective value of the terminal voltage loaded on the AC motor winding can be adjusted. The other end of the voltage regulating circuit 10 is connected to the voltage stabilizing circuit 20. The voltage regulating circuit 10 may include multiple resistors and at least one adjustable resistor. The multiple resistors and the adjustable resistor are connected in series with each other. The voltage of the voltage regulating circuit 10 can be adjusted by changing the resistance value of the adjustable resistor to change the voltage regulation value.

[0057] One end of the voltage stabilizing circuit 20 is connected to the power supply 200, and the other end of the voltage stabilizing circuit 20 is connected to the speed regulating device 30. At the same time, the voltage stabilizing circuit 20 is also connected to the voltage regulating circuit 10. The voltage stabilizing circuit 20 may include a diode, which has a voltage stabilizing value, and the voltage stabilizing value is adjusted by the voltage regulating value of the voltage regulating circuit 10. Preferably, the voltage stabilizing circuit 20 may include a bidirectional diode VD. In addition, the power supply 200 may be an AC power supply for powering the AC motor 300.

[0058] One end of the speed regulating device 30 is connected to the voltage stabilizing circuit 20, and the other end of the speed regulating device 30 is connected to the AC motor 300 for adjusting the speed of the AC motor 300. The speed regulating device 30 may be a bidirectional thyristor VS, and the bidirectional thyristor VS has a conduction angle α, and the angle of the conduction angle α is related to the voltage stabilizing value of the voltage stabilizing circuit 20. At the same time, the conduction angle α is related to the voltage waveform of the AC motor 300, and can change the effective value of the terminal voltage of the AC motor 300, thereby smoothly adjusting the speed of the AC motor 300.

[0059] When in use, the voltage regulation value of the voltage regulating circuit 10 can be adjusted to adjust the voltage regulation value of the voltage stabilizing circuit 20 , and then the conduction angle α of the speed regulating device 30 can be adjusted, thereby achieving speed regulation of the AC motor 300 .

[0060] When the voltage regulation value changes, the voltage stabilization value also changes, causing the conduction angle α of the bidirectional thyristor VS to change. The conduction angle α is related to the actual voltage applied to the AC motor winding, thereby affecting the speed of the AC motor 300. Figure 5 As shown, when the conduction angle α is larger, the actual voltage applied to the AC motor winding is larger. Since the bidirectional thyristor VS includes two unidirectional thyristors, smooth speed regulation can be achieved.

[0061] The utility model discloses a speed regulation circuit and a speed regulation system for an AC motor. The voltage regulation value is adjusted by a voltage regulation circuit, and the voltage regulation value of a voltage stabilizing circuit is adjusted by the voltage regulation value. The speed regulation device can adjust the rotation speed of the AC motor, and the speed regulation of the speed regulation device is related to the voltage stabilizing value of the voltage stabilizing circuit. Thus, smooth speed regulation of the AC motor can be achieved, and the circuit cost is relatively low.

[0062] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the utility model, and these modifications or replacements should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A speed control circuit for an AC motor, characterized in that: include: A voltage regulating circuit, one end of which is connected to the AC motor; A voltage stabilizing circuit, one end of which is connected to the other end of the voltage regulating circuit, and the other end of which is connected to a power supply; A speed regulating device, one end of which is connected to the other end of the voltage stabilizing circuit and the power supply respectively, and the other end of which is connected to the AC motor; Wherein, the voltage regulating value of the voltage regulating circuit is adjusted to adjust the voltage stabilizing value of the voltage stabilizing circuit so as to control the speed regulating device to adjust the speed of the AC motor.

2. The speed regulating circuit of the AC motor according to claim 1, characterized in that: The speed regulating device is a bidirectional thyristor, a controlled end of the bidirectional thyristor is connected to the voltage stabilizing circuit, an input end of the bidirectional thyristor is connected to the power supply, and an output end of the bidirectional thyristor is connected to the AC motor.

3. The speed regulating circuit of the AC motor according to claim 2, characterized in that: The voltage regulating circuit includes a first adjustable resistor, one end of the first adjustable resistor is connected to the AC motor, and the other end of the first adjustable resistor is connected to the voltage stabilizing circuit.

4. The speed regulating circuit of the AC motor according to claim 3, characterized in that: The voltage regulating circuit further includes a first resistor, one end of which is connected to the AC motor, and the other end of which is connected to the first adjustable resistor.

5. The speed regulating circuit of the AC motor according to claim 2, characterized in that: The voltage stabilizing circuit comprises a bidirectional diode, one end of the bidirectional diode is connected to the power supply, and the other end of the bidirectional diode is connected to the speed regulating device.

6. The speed regulating circuit of the AC motor according to claim 5, characterized in that: The voltage stabilizing circuit further includes a first capacitor, one end of which is connected to the power supply, and the other end of which is connected to the speed regulating circuit and the bidirectional diode respectively.

7. The speed regulating circuit of the AC motor according to claim 1, characterized in that: It also includes a protection circuit, one end of which is connected to the power supply, and the other end of which is connected to the voltage stabilizing circuit and the speed regulating device respectively.

8. The speed regulating circuit of the AC motor according to claim 7, characterized in that: The protection circuit comprises a second resistor, one end of the second resistor is connected to the power supply, and the other end of the second resistor is respectively connected to the voltage stabilizing circuit and the speed regulating device.

9. The speed regulating circuit of the AC motor according to claim 1, characterized in that: It also includes a second capacitor, which is connected between the main phase winding and the auxiliary phase winding of the AC motor.

10. A speed control system for an AC motor, characterized in that: A speed regulating circuit comprising a power supply and an AC motor as claimed in any one of claims 1 to 9; The power supply is respectively connected to the voltage stabilizing circuit and the speed regulating device of the speed regulating circuit of the AC motor.

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