Motor speed regulation circuit and motor speed regulator

Abstract

The utility model relates to the field of motor speed regulation circuits, and discloses a motor speed regulation circuit and a motor speed regulator. The motor speed regulation circuit comprises a conduction circuit, a speed regulation circuit, a restart protection circuit, a switch and a motor, and an external alternating current power supply is connected with the conduction circuit and the motor through the switch and used for supplying power to the motor; the conduction circuit is connected with the motor and is used for supplying power to the motor in a conduction state; the speed regulation circuit is connected with the motor for changing the rotating speed of the motor; and the restart protection circuit is connected with the conduction circuit and is used for enabling the motor speed regulation circuit to be in a restart protection state when conditions are met. The motor speed regulation circuit is provided with the restart protection circuit, so that the problem that restart protection cannot be effectively triggered or the speed regulation function is affected due to mutual interference between the restart protection circuit and the motor speed regulation circuit is effectively solved.

Description

Technical Field

[0001] The utility model relates to the field of motor speed regulation circuits, in particular to a motor speed regulation circuit and a motor speed regulator. Background Art

[0002] Motor speed regulation is a speed regulation method widely used in production machinery without changing the synchronous speed. The methods of motor speed regulation include rotor series resistance speed regulation of wound-rotor motors, chopper speed regulation, cascade speed regulation, and the use of electromagnetic slip clutches, hydraulic couplings, oil film clutches, etc.

[0003] The phase-shifted motor speed regulator has the characteristics of simple structure and low cost, so it has been widely used in motor speed regulation. Due to the simple structure of the motor speed regulation circuit, the expansion of other functions based on the motor speed regulation circuit is subject to many restrictions. Adding a restart protection function to the motor speed regulation circuit, the restart protection circuit with the restart protection function and the motor speed regulation circuit will interfere with each other due to compatibility issues. The mutual interference will seriously affect the speed regulation performance, and the restart protection function will affect the realization of the function due to the mutual interference between the motor speed regulation circuit and the restart protection circuit. In summary, the motor speed regulation circuit has the problem that the restart protection circuit and the motor speed regulation circuit cannot effectively trigger the restart protection function due to the mutual interference problem. Utility Model Content

[0004] In view of this, the utility model provides a motor speed regulation circuit and a motor speed regulator to solve the problem that the restart protection circuit and the motor speed regulation circuit cannot effectively trigger the restart protection function due to mutual interference.

[0005] In a first aspect, the utility model provides a motor speed control circuit, including a conduction circuit, a speed control circuit, a restart protection circuit, a switch SW and a motor M, wherein:

[0006] The restart protection circuit and the conduction circuit are both connected to the switch SW, the restart protection circuit is connected to the conduction circuit through the speed regulation circuit, and the conduction circuit is connected to the motor M;

[0007] The restart protection circuit includes: a first switch tube Q1, a second switch tube Q2, a first resistor R1 and a second resistor R2, wherein:

[0008] The gate of the first switch tube Q1 is connected to the collector of the second switch tube Q2, the drain of the first switch tube Q1 is connected to one end of the first resistor R1, and the drain of the first switch tube Q1 is also connected to the second terminal of the conduction circuit;

[0009] The source of the first switch tube Q1 is connected to the emitter of the second switch tube Q2, a first resistor R1 and a second resistor R2 are connected in series between the drain of the first switch tube Q1 and the emitter of the second switch tube Q2, a base of the second switch tube Q2 is connected to a common end of the first resistor R1 and the second resistor R2, and one end of the second resistor R2 is connected to a second power supply terminal N of an external AC power supply.

[0010] The motor speed regulation circuit provided by the utility model comprises a conduction circuit, a speed regulation circuit, a restart protection circuit, a switch SW and a motor M. The motor speed regulation circuit is connected to an external AC power supply, and the external AC power supply is used to power the motor speed regulation circuit, and further to power the motor M; the switch SW is used to control closing or closing, and further to turn on or off the motor M; the conduction circuit is connected to the motor M, and is used to conduct the motor M under the conduction condition; the speed regulation circuit is connected to the motor M, and is used to change the voltage of the motor M, and further to change the speed of the motor M;

[0011] Compared with conventional motor speed control circuits, the utility model is further provided with a restart protection circuit, which is used when the motor speed control circuit is connected to an external AC power supply and the switch SW is closed, or when the power supply suddenly fails during the operation of the motor and then powers on again, the restart protection circuit causes the motor speed control circuit to enter a restart protection state, thereby further stopping the operation of the motor M.

[0012] In combination with the first aspect, in an optional implementation, the conduction circuit includes a first capacitor C1, a first diode D1 and a third switch tube Q3;

[0013] One end of the first capacitor C1 is connected to the drain of the first switch tube Q1 , the other end of the first capacitor is connected to one end of the third switch tube Q3 through the first diode D1 , and the other end of the third switch tube is connected to the motor M.

[0014] When the motor speed control circuit is connected to an external AC power supply, if the switch SW is turned off, the current charges the second capacitor C2 through the first power supply terminal L, the second diode D2, the fourth resistor R4, and the fifth resistor R5. When the second capacitor C2 is fully charged and becomes a high level, the level is also added to the gate of the first switch tube Q1, so that the first switch tube Q1 is turned on. At this time, the first switch tube Q1 and the speed control circuit are in a standby state, and the base of the second switch tube Q2 cannot be turned on because there is no bias voltage.

[0015] At this time, if the switch SW is closed, the motor speed control circuit enters the working state; in the positive half cycle of the power supply, the current forms a path through the switch SW, the motor M, the third resistor R3, the adjustment potentiometer VR1, and the first switch tube Q1 to charge the first capacitor C1. When the first capacitor C1 is fully charged, it discharges the first diode D1, the first diode D1 avalanche breakdown, and the current is added to the trigger pole G of the third switch tube Q3, the third switch tube Q3 is triggered to turn on, and the current is transmitted to the motor M, and the motor M starts to run; in the negative half cycle of the power supply, the current forms a path through the first switch tube Q1, the first capacitor C1, the adjustment potentiometer VR1, the third resistor R3, the motor M and the switch SW to charge the first capacitor C1. When the first capacitor C1 is fully charged, it discharges the first diode D1, the first diode D1 avalanche breakdown, and the current is added to the trigger pole G of the third switch tube Q3, the third switch tube Q3 is triggered to turn on, and the current is transmitted to the motor M, and the motor M starts to run.

[0016] In combination with the first aspect, in another optional implementation, the speed control circuit includes a third resistor R3 and a speed control dial;

[0017] One end of the third resistor R3 is connected to the other end of the third switch tube Q3 , and the other end of the third resistor R3 is connected to the other end of the first capacitor C1 through the speed adjustment dial.

[0018] The third resistor R3 and the speed dial in the speed control circuit both have resistance values. By rotating the speed dial, the resistance value in the speed control circuit changes, the voltage of the motor M connected to the speed control circuit 3 changes, and further the speed of the motor M changes according to the speed dial.

[0019] In combination with the first aspect, in another optional implementation, the speed dial includes a first fixed end, a second fixed end, and a sliding end; the first fixed end is connected to the other end of the third resistor R3, and the second fixed end and the sliding end are both connected to the other end of the first capacitor C1. The rotation of the speed dial corresponds to the change of the sliding end. When the sliding end slides toward the first fixed end, the resistance of the speed dial decreases, and when the sliding end slides toward the second fixed end, the resistance of the speed dial increases.

[0020] In combination with the first aspect, in another optional implementation, the speed adjustment dial is an adjustment potentiometer VR1.

[0021] In combination with the first aspect, in another optional implementation, the restart protection circuit further includes a second diode D2 and a fourth resistor R4; the second diode D2 includes an input end and an output end; the input end of the second diode D2 is connected to the first power terminal L of the external AC power supply, and the output end of the second diode D2 is connected to the gate of the first switch tube Q1 through the fourth resistor R4. The input end of the second diode D2 is connected to the first power terminal L of the external AC power supply, and the output end outputs the power supply of the first power terminal L of the external AC power supply. According to the device characteristics of the second diode D2, the second diode D2 isolates the power supply of the second power terminal N of the external AC power supply.

[0022] In combination with the first aspect, in another optional implementation, the restart protection circuit further includes a fifth resistor R5 and a second capacitor C2; one end of the fifth resistor R5 is connected to the gate of the first switch tube Q1, and the other end of the fifth resistor R5 is connected to the second power terminal N of the external AC power supply; the second capacitor C2 is connected in parallel with the fifth resistor R5. The second capacitor C2 receives power from the first power terminal L of the external AC power supply and the second power terminal N of the external AC power supply, and when the second capacitor C2 is fully charged, it supplies power to the gate of the first switch tube Q1.

[0023] In combination with the first aspect, in another optional implementation, the third switch tube Q3 is a bidirectional thyristor. The bidirectional thyristor has bidirectional conductivity.

[0024] In combination with the first aspect, in another optional implementation, the first diode D1 is a bidirectional trigger diode. The bidirectional trigger diode has bidirectional conductivity.

[0025] In a second aspect, the utility model further provides a motor speed regulator, which includes the motor speed regulation circuit in the aforementioned first aspect or any one of the embodiments of the first aspect.

[0026] During normal use, the first power terminal L of the external AC power source and the second power terminal N of the external AC power source are connected to the motor speed regulator, the switch SW is closed, the motor M starts to run, and the speed of the motor M can be adjusted by rotating the speed dial.

[0027] However, if the first power terminal L of the external AC power supply and the second power terminal N of the external AC power supply start to supply power, if the switch SW is in the closed state first, the motor M needs to stop running at this time, in order to prevent the motor M from suddenly running and injuring the user when the first power terminal L of the external AC power supply and the second power terminal N of the external AC power supply are supplying power. This requires the motor speed regulator to detect the state of the switch SW at the moment of power-on. The switch SW is turned off at power-on, and the motor speed regulation circuit enters the standby state. When the switch SW is closed, the motor speed regulation circuit enters the working state, and the motor M operates normally. If the switch SW is already closed at power-on, the restart protection circuit acts on the motor speed regulation circuit and the conduction circuit, so that the conduction circuit is in a non-conducting state, and further the motor speed regulation circuit enters the restart protection state, and the motor M continues to stop running. When the switch SW is turned off and then closed again, the motor speed regulation circuit re-enters the working state, and the motor M operates normally. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a structural schematic diagram of a motor speed regulation circuit according to an embodiment of the utility model;

[0030] Figure 2 It is another structural schematic diagram of a motor speed control circuit according to an embodiment of the utility model;

[0031] Figure 3 It is a structural schematic diagram of a motor speed regulator according to an embodiment of the utility model. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the utility model clearer, the technical solutions in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments.

[0033] like Figure 1 As shown, the utility model provides a motor speed regulation circuit, including a conduction circuit 1, a speed regulation circuit 3, a restart protection circuit 2, a switch SW and a motor M, wherein:

[0034] The restart protection circuit 2 and the conduction circuit 1 are both connected to the switch SW. The restart protection circuit 2 is connected to the conduction circuit 1 through the speed regulation circuit 3. The conduction circuit 1 is connected to the motor M.

[0035] like Figure 2 As shown, the restart protection circuit 2 includes: a first switch tube Q1, a second switch tube Q2, a first resistor R1 and a second resistor R2, wherein:

[0036] The gate of the first switch tube Q1 is connected to the collector of the second switch tube Q2 , the drain of the first switch tube Q1 is connected to one end of the first resistor R1 , and the drain of the first switch tube Q1 is also connected to the second terminal of the conduction circuit 1 .

[0037] The source of the first switch tube Q1 is connected to the emitter of the second switch tube Q2, a first resistor R1 and a second resistor R2 are connected in series between the drain of the first switch tube Q1 and the emitter of the second switch tube Q2, a base of the second switch tube Q2 is connected to a common end of the first resistor R1 and the second resistor R2, and one end of the second resistor R2 is connected to a second power supply terminal N of an external AC power supply.

[0038] In this embodiment, the first switch tube Q1 is a MOS tube, and the second switch tube Q2 is a triode; there is a clamping relationship between the first switch tube Q1 and the second switch tube Q2. When the motor speed control circuit is connected to the external AC power supply, the switch SW is turned off, the first switch tube Q1 is turned on and the second switch tube Q2 remains off. At this time, the power supply of the external AC power supply is transmitted to the conduction circuit through the first switch tube Q1; when the motor speed control circuit is connected to the external AC power supply, the switch SW is closed, the first switch tube Q1 remains off and the second switch tube Q2 is turned on. At this time, the motor speed control circuit enters the restart protection state, and the motor M stops running.

[0039] The motor speed regulation circuit provided by the utility model includes a conduction circuit 1, a speed regulation circuit 3, a restart protection circuit 2, a switch SW and a motor M. The motor speed regulation circuit is connected to an external AC power supply, and the external AC power supply is used to power the motor speed regulation circuit, and further used to power the motor M; the switch SW is used to manually control closing or closing, and further turn on or off the motor M; the conduction circuit 1 is connected to the motor M, and is used to conduct the motor M under the conduction condition; the speed regulation circuit 3 is connected to the motor M, and is used to change the voltage of the motor M, and further change the speed of the motor M.

[0040] Compared with conventional motor speed control circuits, the utility model is further provided with a restart protection circuit 2, which is used to restart the motor speed control circuit when the motor speed control circuit is connected to an external AC power supply and the switch SW is closed. At this time, the restart protection circuit 2 makes the motor speed control circuit enter a restart protection state, further stopping the motor M from running.

[0041] In this embodiment, the conduction circuit 1 further includes a first capacitor C1, a first diode D1 and a third switch tube Q3.

[0042] One end of the first capacitor C1 is connected to the drain of the first switch tube Q1 , the other end of the first capacitor is connected to one end of the third switch tube Q3 through the first diode D1 , and the other end of the third switch tube is connected to the motor M.

[0043] The motor speed control circuit is connected to an external AC power supply, and the external AC power supply has positive and negative half cycles for the motor speed control circuit to work: in the positive half cycle, the power supply current of the first power terminal L flows to the second power terminal N; in the negative half cycle, the power supply current of the second power terminal N flows to the first power terminal L.

[0044] When the motor speed control circuit is connected to an external AC power supply, if the switch SW is turned off, the current charges the second capacitor C2 through the first power supply terminal L, the second diode D2, the fourth resistor R4, and the fifth resistor R5. When the second capacitor C2 is fully charged and becomes a high level, the level is also added to the gate of the first switch tube Q1 at the same time, so that the first switch tube Q1 is turned on. At this time, the first switch tube Q1 and the speed control circuit are in a standby state, and the base of the second switch tube Q2 cannot be turned on because there is no bias voltage surface. At this time, the motor speed control circuit enters a standby state.

[0045] At this time, if the switch SW is closed, the motor speed control circuit enters the working state; in the positive half cycle of the power supply, the current forms a path through the switch SW, the motor M, the third resistor R3, the adjustment potentiometer VR1, and the first switch tube Q1 to charge the first capacitor C1. When the first capacitor C1 is fully charged, it discharges the first diode D1, the first diode D1 avalanche breakdown, and the current is added to the trigger pole G of the third switch tube Q3, the third switch tube Q3 is triggered to turn on, and the current is transmitted to the motor M, and the motor M starts to run; in the negative half cycle of the power supply, the current forms a path through the first switch tube Q1, the first capacitor C1, the adjustment potentiometer VR1, the third resistor R3, the motor M and the switch SW to charge the first capacitor C1. When the first capacitor C1 is fully charged, it discharges the first diode D1, the first diode D1 avalanche breakdown, and the current is added to the trigger pole G of the third switch tube Q3, the third switch tube Q3 is triggered to turn on, and the current is transmitted to the motor M, and the motor M starts to run.

[0046] When the motor speed control circuit is connected to the external AC power supply, if the switch SW remains closed, the motor speed control circuit enters the restart protection state. When the first power supply terminal L of the external AC power supply supplies power in each positive half cycle, the power is supplied through the third resistor R3, the adjustment potentiometer VR1, the first capacitor C1, the first resistor R1, and the second resistor R2 to provide a bias current for the base of the second switch tube Q2. The second switch tube Q2 is turned on and periodically discharges the charge of the second capacitor C2, so that the second capacitor C2 cannot be charged to a high level to trigger the first switch tube Q1 to turn on.

[0047] Since the first switch tube Q1 cannot be turned on, the voltage across the first capacitor C1 cannot be charged to avalanche breakdown of the first diode D1 in each half cycle of the power supply, the third switch tube Q3 cannot be triggered to turn on, the conduction circuit 1 always remains in the closed state, the motor M cannot be powered on and remains in the restart protection state.

[0048] In this embodiment, the speed regulating circuit 3 includes a third resistor R3 and a speed regulating dial.

[0049] One end of the third resistor R3 is connected to the other end of the third switch tube Q3 , and the other end of the third resistor R3 is connected to the other end of the first capacitor C1 through the speed adjustment dial.

[0050] The third resistor R3 and the speed dial in the speed control circuit 3 both have resistance values. By rotating the speed dial, the resistance value in the speed control circuit 3 changes, the voltage of the motor M connected to the speed control circuit 3 changes, and further the speed of the motor M changes according to the speed dial.

[0051] In this embodiment, the speed regulating dial includes a first fixed end, a second fixed end and a sliding end.

[0052] The first fixed end is connected to the other end of the third resistor R3 , and the second fixed end and the sliding end are both connected to the other end of the first capacitor C1 .

[0053] The rotation of the speed dial corresponds to the change of the sliding end. When the sliding end slides toward the first fixed end, the resistance of the speed dial decreases. When the sliding end slides toward the second fixed end, the resistance of the speed dial increases.

[0054] In this embodiment, the speed adjustment dial is an adjustment potentiometer VR1.

[0055] In this embodiment, the speed dial is used for voltage regulation by phase shifting, which means that from the moment the current passes through zero, the trigger point is changed within the electrical angle range of 0° to 180°. The larger the angle, the lower the output voltage. The parameters of the third resistor R3, the adjustment potentiometer VR1 and the first capacitor C1 in this embodiment are set according to the voltage regulation range.

[0056] In this embodiment, the restart protection circuit 2 further includes a second diode D2 and a fourth resistor R4.

[0057] The second diode D2 includes an input terminal and an output terminal.

[0058] An input end of the second diode D2 is connected to a first power terminal L of an external AC power source, and an output end of the second diode D2 is connected to a gate of the first switch tube Q1 via a fourth resistor R4.

[0059] The input end of the second diode D2 is connected to the first power terminal L of the external AC power supply, and the output end outputs the power supply of the first power terminal L of the external AC power supply. According to the device characteristics of the second diode D2, the second diode D2 isolates the power supply of the second power terminal N of the external AC power supply.

[0060] In this embodiment, the restart protection circuit 2 further includes a fifth resistor R5 and a second capacitor C2.

[0061] One end of the fifth resistor R5 is connected to the gate of the first switch tube Q1 , and the other end of the fifth resistor R5 is connected to the second power terminal N of the external AC power supply; the second capacitor C2 is connected in parallel with the fifth resistor R5 .

[0062] The second capacitor C2 receives power from the first power terminal L of the external AC power source and the first power terminal L of the external AC power source, and supplies power to the gate of the first switch tube Q1 when the second capacitor C2 is fully charged.

[0063] In this embodiment, the third switch tube Q3 is a bidirectional thyristor.

[0064] The bidirectional thyristor has bidirectional conductivity according to the power supply direction; according to actual usage, the bidirectional thyristor in this embodiment can be replaced by a unidirectional thyristor.

[0065] In this embodiment, the first diode D1 is a bidirectional trigger diode.

[0066] The bidirectional trigger diode has bidirectional conductivity after avalanche breakdown depending on the power supply direction.

[0067] The motor speed control circuit in this embodiment has three working states, namely, a standby state, a working state and a restart protection state.

[0068] When the motor speed control circuit is connected to an external AC power supply, if the switch SW is turned off, the current charges the second capacitor C2 through the first power supply terminal L, the second diode D2, the fourth resistor R4, and the fifth resistor R5 in the positive half cycle. When the second capacitor C2 is fully charged and becomes a high level, the level is also added to the gate of the first switch tube Q1 at the same time, so that the first switch tube Q1 is turned on. And the base of the second switch tube Q2 cannot be turned on because there is no bias voltage surface. At this time, the motor speed control circuit enters the standby state.

[0069] At this time, if the switch SW is closed, the motor speed control circuit enters the working state; in the positive half cycle of the power supply, the current forms a path through the switch SW, the motor M, the third resistor R3, the adjustment potentiometer VR1, and the first switch tube Q1 to charge the first capacitor C1. When the first capacitor C1 is fully charged, it discharges the first diode D1, the first diode D1 avalanche breakdown, and the current is added to the trigger pole G of the third switch tube Q3, the third switch tube Q3 is triggered to turn on, and the current is transmitted to the motor M, and the motor M starts to run; in the negative half cycle of the power supply, the current forms a path through the first switch tube Q1, the first capacitor C1, the adjustment potentiometer VR1, the third resistor R3, the motor M and the switch SW to charge the first capacitor C1. When the first capacitor C1 is fully charged, it discharges the first diode D1, the first diode D1 avalanche breakdown, and the current is added to the trigger pole G of the third switch tube Q3, the third switch tube Q3 is triggered to turn on, and the current is transmitted to the motor M, and the motor M starts to run.

[0070] When the motor speed control circuit is connected to the external AC power supply and the switch SW is closed, in the positive half cycle of the power supply, the power supply of the first power supply terminal L of the external AC power supply is transmitted to the fifth resistor R5 and the second capacitor C2 through the second diode D2 and the fourth resistor R4 to charge the second capacitor C2; at the same time, the power supply is transmitted to the first capacitor C1 through the switch SW, the motor M, the third resistor R3 and the adjustment potentiometer VR1. Since the charging time constant of the second capacitor C2 in this embodiment is relatively large, the charging voltage at both ends rises relatively slowly in each positive half cycle of the power supply, and the voltage is very low. At the same time, in each positive half cycle of the power supply, the charging current of the first capacitor C1 will pass through the first resistor R1 and the second resistor R2 to provide a bias current for the base of the second switch tube Q2, so that the second switch tube Q2 is turned on, and the charge of the second capacitor C2 is discharged, so that the voltage at both ends of the second capacitor C2 is always maintained at a low value, and the first switch tube Q1 cannot be triggered to turn on. The first capacitor C1 cannot be normally charged to a higher voltage in each power half cycle, and further avalanche breaks down the first diode D1. The third switch tube Q3 cannot be triggered to conduct, and the motor speed control circuit enters the restart protection state, and the motor M stops running. If the switch SW is disconnected at this time, according to the above steps, the motor speed control circuit will enter the standby state. At this time, if the switch SW is closed again, the motor speed control circuit enters the normal working state.

[0071] like Figure 3 As shown, the utility model also provides a motor speed regulator, which includes the motor speed regulation circuit in any of the aforementioned embodiments.

[0072] During normal use, the first power terminal L of the external AC power source and the second power terminal N of the external AC power source are connected to the motor speed regulator, the switch SW is closed, the motor M starts to run, and the speed of the motor M can be adjusted by rotating the speed dial.

[0073] However, if the first power terminal L of the external AC power source and the second power terminal N of the external AC power source start to supply power, if the switch SW is in a closed state first, the motor M needs to stop running at this time, in order to prevent the motor M from suddenly running and injuring the user when the first power terminal L of the external AC power source and the second power terminal N of the external AC power source are supplying power. This requires the motor speed regulator to detect the state of the switch SW at the moment of power-on. The switch SW is turned off when power is on, and the motor speed regulation circuit enters the standby state. When the switch SW is closed, the motor M operates normally. If the switch SW is closed when power is on, the restart protection circuit acts on the motor speed regulation circuit, making the conduction circuit in a non-conducting state, and further making the motor speed regulation circuit enter the restart protection state, and the motor M continues to stop running. When the switch SW is turned off and then closed again, the motor speed regulation circuit re-enters the normal working state, and the motor M operates normally.

[0074] The motor speed regulation circuit in this embodiment eliminates mutual interference between devices in different circuits by selecting parameters of each component in the circuit, so that the motor speed regulation circuit can work normally while the restart protection circuit can act on the motor speed regulation circuit to perform a normal restart protection function. Therefore, the motor speed regulation circuit and the motor speed regulator in this embodiment realize the restart protection function and the speed regulation function.

[0075] In the description of this specification, the description with reference to the terms "this embodiment", "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0076] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0077] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0078] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A motor speed control circuit, characterized in that: It includes a conduction circuit, a speed regulation circuit, a restart protection circuit, a switch SW and a motor M, wherein: The restart protection circuit and the conduction circuit are both connected to the switch SW, the restart protection circuit is connected to the conduction circuit through the speed regulation circuit, and the conduction circuit is connected to the motor M; The restart protection circuit includes: a first switch tube Q1, a second switch tube Q2, a first resistor R1 and a second resistor R2, wherein: The gate of the first switch tube Q1 is connected to the collector of the second switch tube Q2, the drain of the first switch tube Q1 is connected to one end of the first resistor R1, and the drain of the first switch tube Q1 is also connected to the second terminal of the conduction circuit; The source of the first switch tube Q1 is connected to the emitter of the second switch tube Q2, the first resistor R1 and the second resistor R2 are connected in series between the drain of the first switch tube Q1 and the emitter of the second switch tube Q2, the base of the second switch tube Q2 is connected to the common end of the first resistor R1 and the second resistor R2, and one end of the second resistor R2 is connected to the second power supply terminal N of the external AC power supply.

2. The motor speed control circuit according to claim 1, characterized in that: The conduction circuit includes a first capacitor C1, a first diode D1 and a third switch tube Q3; One end of the first capacitor C1 is connected to the drain of the first switch tube Q1 , the other end of the first capacitor is connected to one end of the third switch tube Q3 through the first diode D1 , and the other end of the third switch tube is connected to the motor M.

3. The motor speed control circuit according to claim 2, characterized in that: The speed regulating circuit includes a third resistor R3 and a speed regulating dial; One end of the third resistor R3 is connected to the other end of the third switch tube Q3 , and the other end of the third resistor R3 is connected to the other end of the first capacitor C1 through the speed adjustment dial.

4. The motor speed control circuit according to claim 3, characterized in that: The speed dial comprises a first fixed end, a second fixed end and a sliding end; The first fixed end is connected to the other end of the third resistor R3 , and the second fixed end and the sliding end are both connected to the other end of the first capacitor C1 .

5. The motor speed control circuit according to claim 4, characterized in that: The speed regulating dial is an adjusting potentiometer VR1.

6. The motor speed control circuit according to claim 1, characterized in that: The restart protection circuit also includes a second diode D2 and a fourth resistor R4; The second diode D2 includes an input end and an output end; An input end of the second diode D2 is connected to the first power terminal L of the external AC power source, and an output end of the second diode D2 is connected to the gate of the first switch tube Q1 through the fourth resistor R4.

7. The motor speed control circuit according to claim 1, characterized in that: The restart protection circuit also includes a fifth resistor R5 and a second capacitor C2; One end of the fifth resistor R5 is connected to the gate of the first switch tube Q1, and the other end of the fifth resistor R5 is connected to the second power terminal N of the external AC power supply; the second capacitor C2 is connected in parallel with the fifth resistor R5.

8. The motor speed control circuit according to claim 2, characterized in that: The third switch tube Q3 is a bidirectional thyristor.

9. The motor speed control circuit according to claim 2, characterized in that: The first diode D1 is a bidirectional trigger diode.

10. A motor speed regulator, characterized in that: The invention comprises the motor speed control circuit according to any one of claims 1 to 9.

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