Motor speed regulating device and extractor hood

Abstract

The application discloses a motor speed regulating device and an extractor hood, wherein the motor speed regulating device comprises a tap speed regulating circuit and a stepless speed regulating circuit, the motor is connected to a power supply through the tap speed regulating circuit and the stepless speed regulating circuit respectively, and the operation of the motor is controlled through the tap speed regulating circuit or the stepless speed regulating circuit. The motor speed is controlled by the tap speed regulating circuit and the stepless speed regulating circuit, the motor is controlled to operate at super high speed by the tap speed regulating circuit, the motor is controlled to operate at high speed, medium speed and low speed by the stepless speed regulating circuit, and the motor can maintain high operation efficiency when operating at low speed or super high speed.

Description

Technical Field

[0001] This invention belongs to the field of range hood technology, specifically, it relates to a motor speed control device and a range hood. Background Technology

[0002] A range hood is a kitchen appliance that purifies the kitchen environment. Installed above the stove, it quickly removes waste from combustion and harmful fumes produced during cooking, expelling them outdoors, reducing pollution, purifying the air, and providing safety features such as protection against toxic substances and explosions.

[0003] Because range hood motors have low power, the industry generally uses single-phase AC motors with starting and running capacitors. Speed ​​regulation is achieved through tap-based adjustment, where a switch changes the wiring of the intermediate winding, starting winding, and working winding, thereby altering the magnitude of the air gap magnetic field inside the motor and adjusting its speed. However, this method has a narrow speed range, preventing the motor from reaching very low speeds, and the motor's efficiency decreases as the speed decreases.

[0004] Another speed control method is to use stepless speed regulation. First, the AC input voltage is rectified into a pulsating DC voltage. Then, an inverter bridge circuit is used to convert the pulsating DC voltage into a controllable AC output voltage, thereby regulating the speed of the single-phase AC motor. However, with this method, once the motor speed increases to a certain value, the system efficiency decreases as the motor speed increases.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a motor speed control device to solve the problems in the prior art where the speed cannot be very low when the winding tap controls the motor, the efficiency of the motor decreases as the speed decreases, and the efficiency of the continuously variable speed control motor is low at ultra-high speeds.

[0007] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0008] A motor speed control device includes a tapped speed control circuit and a stepless speed control circuit. The motor is connected to a power supply through the tapped speed control circuit and the stepless speed control circuit, respectively, and the operation of the motor is controlled by the tapped speed control circuit or the stepless speed control circuit.

[0009] Furthermore, the motor includes a first main winding, an auxiliary winding connected in parallel with the first main winding, and a capacitor connected in series with the auxiliary winding. The first end of the first main winding is connected to a tap position lead wire, and the second end of the first main winding is electrically connected to the first end of the power supply.

[0010] The tap speed control circuit includes a relay, and the tap speed lead is electrically connected / disconnected to the second terminal of the power supply through the relay.

[0011] Furthermore, the normally closed terminal of the relay is electrically connected to the second terminal of the power supply, the normally open terminal of the relay is electrically connected to the tap position lead, and the control terminal of the relay is connected to a control unit for controlling the operation of the relay.

[0012] Furthermore, the tap speed control circuit also includes a thermal protector, the first end of which is connected to the first end of the first main winding, and the second end of which is connected to the power supply lead; preferably, the thermal protector is a fuse.

[0013] Furthermore, the stepless speed regulation circuit includes a motor drive module, which is connected in parallel between the motor and the power supply to control the effective value of the AC voltage supplied to the motor; preferably, a control unit for controlling the operation of the motor drive module is connected to the motor drive module.

[0014] Furthermore, the motor drive module includes a rectifier circuit and a switching circuit electrically connected to the rectifier circuit. The rectifier circuit is used to rectify the AC input voltage generated by the power supply into a pulsating DC voltage, and the switching circuit is used to convert the pulsating DC voltage into an AC output voltage.

[0015] Furthermore, it also includes a signal generating circuit electrically connected to the switching circuit, the signal generating circuit controlling the on / off state of the transistor in the switching circuit and chopping the AC output voltage;

[0016] Preferably, it also includes a low-voltage power supply circuit, which is electrically connected to both the power supply and the signal generation circuit, and is used to provide the required DC regulated power supply to the signal generation circuit.

[0017] Furthermore, the motor also includes a second main winding, which is connected in series with the first main winding and in parallel with the auxiliary winding.

[0018] Furthermore, it also includes an input unit, the control unit being used to receive control commands from the input unit and control the tap speed regulation circuit or the stepless speed regulation circuit to operate according to the control commands.

[0019] The present invention also provides a range hood, including the motor speed control device described above.

[0020] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0021] This invention employs both tapped speed control circuit and stepless speed control circuit to control the motor speed. The tapped speed control circuit controls the motor to operate at ultra-high speed with high efficiency; the stepless speed control circuit controls the motor to operate at high, medium, and low speeds, providing a wide speed range, including low-speed operation with high efficiency. The tapped speed control circuit and the stepless speed control circuit control the motor speed according to actual needs, enabling the motor to maintain high operating efficiency at both low and ultra-high speeds.

[0022] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0023] The accompanying drawings, as part of this invention, are provided to further illustrate the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation thereof. Clearly, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0024] In the attached diagram:

[0025] Figure 1 This is a circuit diagram of the motor speed control device of the present invention;

[0026] Figure 2 This is the circuit of the motor drive module of the present invention. Figure 1 ;

[0027] Figure 3 This is the circuit of the motor drive module of the present invention. Figure 2 .

[0028] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0030] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] like Figure 1 As shown, the present invention discloses a motor speed control device, including a tap speed control circuit 200 and a stepless speed control circuit 300. The motor M is connected to the power supply 100 through the tap speed control circuit 200 and the stepless speed control circuit 300 respectively, and the operation of the motor M is controlled by the tap speed control circuit 200 or the stepless speed control circuit 300.

[0033] This invention uses a tapped speed control circuit 200 and a stepless speed control circuit 300 to control the speed of motor M as needed. When motor M needs to run at ultra-high speed, the tapped speed control circuit 200 is used for control, resulting in high operating efficiency. When motor M needs to run at high, medium, and low speeds, the stepless speed control circuit 300 is used for control, resulting in a wide speed range and the ability to achieve low-speed operation with high efficiency. The complementary advantages of the two circuits form the optimal speed control scheme for small-power AC motors.

[0034] The ultra-high speed range is 900-1100 rpm; the high speed range is 800-900 rpm; the medium speed range is 600-800 rpm; and the low speed range is 500-600 rpm.

[0035] Furthermore, the motor M includes a first main winding L1, an auxiliary winding L3 connected in parallel with the first main winding L1, and a capacitor C connected in series with the auxiliary winding L3. The first end of the first main winding L1 is connected to a tap position lead H, wherein the tap position lead H is an ultra-high speed tap position lead H. The second end of the first main winding L1 is electrically connected to the first end of the power supply 100.

[0036] Furthermore, the tap speed control circuit 200 includes a relay K, and the tap position lead H is electrically connected / disconnected to the second terminal of the power supply 100 through the relay K.

[0037] The number of relays K is equal to the number of tap position leads H. The relays K are used to connect the power supply 100 to the circuit where the corresponding tap position lead H is located, so as to control the motor M to run at ultra-high speed. For example, the power supply 100 is a 220V AC power supply.

[0038] Furthermore, the normally closed terminal of the relay K is electrically connected to the second terminal of the power supply 100, and the normally open terminal is electrically connected to the tap position lead H. The control terminal of the relay K is connected to a control unit for controlling the opening and closing of the relay K.

[0039] In the above embodiments of the present invention, the motor M is a single-phase AC motor. The motor M includes a first main winding L1 and an auxiliary winding L3 connected in parallel, and a capacitor C connected in series with the auxiliary winding L3. Two wires are led out from the first end of the first main winding L1. The first wire is connected to the thermal protector for connecting to the power supply 100, and the second wire is used as the capacitor wire. The second end of the first main winding L1 is connected to the first end of the second main winding L2 to lead out a tap position lead wire H, which is used to control the motor M to run at ultra-high speed.

[0040] Motor M has such Figure 1 When the ultra-high speed tap position lead-out line H is shown, it is selected by relay K. When the control unit issues a command to control the motor M to run at ultra-high speed, the relay K is energized and closed, connecting the power supply 100 to the circuit where the ultra-high speed tap position lead-out line H of the motor M is located, thereby controlling the motor M to achieve ultra-high speed operation.

[0041] When the control unit does not issue a command to control the motor M to run at ultra-high speed, the relay K is disconnected, the ultra-high speed tap position lead H of the motor M is disconnected from the power supply 100, and the ultra-high speed tap position lead H of the motor M is not connected to the power supply 100. At this time, the control motor M stops running, or the stepless speed regulation circuit 300 can be used to control the motor M to run at high speed, medium speed, and low speed. The user can choose according to actual needs.

[0042] Furthermore, the increase in operating temperature of motor M directly affects the lifespan and operational reliability of both the control unit and motor M. Different insulation classes of motor M windings correspond to different winding temperatures. Exceeding these temperatures will affect the lifespan of motor M, and may even cause motor M to burn out.

[0043] Therefore, the tap speed control circuit 200 also includes a thermal protector F, the first end of which is connected to the first end of the first main winding L1, and the second end of which is connected to the lead of the power supply 100.

[0044] Preferably, the thermal protector F is a fuse, which effectively protects the motor M during operation and prevents damage to the motor M caused by overheating.

[0045] The motor M of this invention requires ultra-high speed operation and is controlled by a tap speed control circuit 200, resulting in high operating efficiency.

[0046] In addition, the stepless speed regulation circuit 300 includes a motor drive module, which is connected in parallel between the motor M and the power supply 100 to control the effective value of the AC voltage supplied to the motor M; preferably, a control unit for controlling the operation of the motor drive module is connected to the motor drive module, and the motor drive module controls the speed of the motor M according to the control instructions of the control unit.

[0047] Furthermore, the motor drive module includes a rectifier circuit 400 and a switching circuit 500 connected to the rectifier circuit 400. The rectifier circuit 400 is used to rectify the AC input voltage generated by the power supply 100 into a pulsating DC voltage, and the switching circuit 500 is used to convert the pulsating DC voltage into an AC output voltage.

[0048] Specifically, such as Figure 2 As shown, the rectifier circuit 400 receives the AC input voltage Vac from the AC power supply and provides the DC bus voltage Vdc after rectification. The switching circuit 500 further converts the DC bus voltage Vdc into an AC drive voltage Vout, thereby driving the motor M to run.

[0049] This motor drive module eliminates the need for a bus capacitor. The AC output voltage Vac provided by the power grid is typically a sine wave, and the rectified DC bus voltage Vdc is a pulsating DC voltage, which serves as the input voltage for the switching circuit 500. This AC motor M drive device does not require filtering with a bus capacitor to obtain a flat DC voltage; it directly supplies power to the motor M with the pulsating DC voltage.

[0050] Furthermore, the switching circuit 500 uses the AC input voltage Vac to control the switching of the current flow path, thereby synchronously generating the AC drive voltage Vout. When the AC power supply is the power grid, both the AC input voltage Vac and the AC drive voltage Vout have power frequency cycles. Within each power frequency cycle, the switching circuit 500 performs high-frequency chopping, thereby changing the effective value of the AC output voltage Vout. Stepless speed regulation of the motor M is achieved through high-frequency chopping.

[0051] The rectifier circuit 400 is a full-bridge rectifier circuit composed of diodes D3 to D4 (third to sixth). Diodes D5 and D6 (fifth and sixth) are connected in series between the first and second output terminals of the rectifier circuit 400. The first input terminal of the rectifier circuit 400 is the midpoint between diodes D3 and D2, and this first input terminal is connected to the live wire L. The second input terminal of the rectifier circuit 400 is the midpoint between diodes D5 and D6, and this second input terminal is connected to the neutral wire N.

[0052] During the operation of the rectifier circuit 400, the third diode D3 and the sixth diode D6 are turned on during the positive half-cycle of the AC input voltage Vin, and the second diode D2 and the fifth diode D5 are turned on during the negative half-cycle of the AC input voltage Vin, so that the current always flows from the first output terminal to the second output terminal of the rectifier circuit 400, thereby generating a pulsating DC voltage as the DC bus voltage Vdc.

[0053] The first and second input terminals of the switching circuit 500 are connected to the first and second output terminals of the rectifier circuit 400, respectively, to receive the DC bus voltage Vdc. The third and fourth input terminals of the switching circuit 500 are connected to the second input terminal of the rectifier circuit 400, respectively. The first and second output terminals of the switching circuit 500 are connected to the AC motor M, thereby providing the latter with an AC drive voltage Vdc.

[0054] The switching circuit 500 includes first to fourth transistors Q1 to Q4, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and first and second diodes D1 and D2. The first transistor Q1 and the second transistor Q2 are connected in series between the first and second input terminals of the switching circuit 500, thus forming the first branch of the switching circuit 500. The third transistor Q3 and the fourth transistor Q4 are connected in series between the first and second input terminals of the switching circuit 500, thus forming the second branch of the switching circuit 500.

[0055] The first transistor Q1 is a PNP transistor, and the second transistor Q2 is an NPN transistor. The emitter of the first transistor Q1 is connected to the first input terminal of the switching circuit 500, and its base is connected to the second input terminal of the rectifier circuit 400 via the first resistor R1. The emitter of the second transistor Q2 is connected to the second input terminal of the switching circuit 500, and its base is connected to the second input terminal of the rectifier circuit 400 via the second resistor R2. The collectors of the first transistor Q1 and the second transistor Q2 are connected to a common first node, which serves as the first output terminal of the switching circuit 500.

[0056] The third transistor Q3 and the fourth transistor Q4 are arbitrary types of switching transistors. For example, the aforementioned switching transistors can be metal-oxide-semiconductor field-effect transistors (MOSFETs). The first terminal of the third transistor Q3 is connected to the first input terminal of the switching circuit 500, and its control terminal receives the PWM signal Vctrl1. The first terminal of the fourth transistor Q4 is connected to the second input terminal of the switching circuit 500, and its control terminal receives the PWM signal Vctrl2. The second terminals of the third transistor Q2 and the fourth transistor Q4 are connected to a common second node, serving as the second output terminal of the switching circuit 500.

[0057] The first diode D1 is connected in reverse parallel between the first and second terminals of the third transistor Q3, and the second diode D2 is connected in reverse parallel between the first and second terminals of the fourth transistor Q4. The first and second diodes D1 and D2 act as freewheeling diodes, providing a path for the reverse current to dissipate when the transistors are turned off, thereby protecting the transistors.

[0058] During the operation of the switching circuit 500, the switching circuit 500 uses the AC input voltage Vac to control the switching of the current flow path, thereby converting the DC bus voltage Vdc into the AC drive voltage Vout, and using PWM signals Vctrl1 and Vctrl2 for chopping. The third transistor Q3 is turned on only during the negative half-cycle of the AC input voltage Vin, and the fourth transistor Q4 is turned on only during the positive half-cycle of the AC input voltage Vin, so that the four transistors work together to control the current flow path.

[0059] During the positive half-cycle of the AC input voltage Vin, the third diode D3 and the fourth diode D4 in the rectifier circuit 400 are turned on. Due to the voltage drop between the third diode D3 and the sixth diode D6 in the on-state, the emitter and base of the first transistor Q1 are forward biased, thus automatically turning on. Simultaneously, the base and emitter of the second transistor Q2 are reverse biased, thus automatically turning off. Therefore, during the positive half-cycle of the AC input voltage Vin, the current in the AC motor M drive device flows sequentially through the third diode D3, the first transistor Q1, the external AC motor M, the fourth transistor Q4, and the sixth diode D6, thereby forming the waveform of the positive half-cycle of the AC drive voltage Vout.

[0060] During the negative half-cycle of the AC input voltage Vin, the fifth diode D5 and the second diode D2 in the rectifier circuit 400 are turned on. Due to the voltage drop of the fifth diode D5 and the second diode D2 in the on-state, the base and emitter of the second transistor Q2 are forward biased, thus automatically turning on. At the same time, the emitter and base of the second transistor Q1 are reverse biased, thus automatically turning off. Therefore, during the negative half-cycle of the AC input voltage Vin, the current in the AC motor M drive device flows sequentially through the fifth diode D5, the second transistor Q2, the external AC motor M, the third transistor Q3, and the second diode D2, thus forming the waveform of the negative half-cycle of the AC drive voltage Vout.

[0061] Because the first transistor Q1 and the second transistor Q2 automatically turn on and off during the power frequency cycle of the AC input voltage Vin, the AC drive voltage Vout used to drive the AC motor M is basically synchronized with the AC input voltage Vin provided by the external AC power supply.

[0062] Furthermore, during the half-cycle of the AC input voltage Vin, the third transistor Q3 and the fourth transistor Q4 are periodically turned on and off under the control of the PWM signals Vctrl1 and Vctrl2, thereby chopping the AC drive voltage Vout.

[0063] PWM signals Vctrl1 and Vctrl2 are, for example, square wave signals with duty cycles. The AC drive voltage Vout after chopping is not a complete sine wave, but a corrected sine wave with zero amplitude during the low-level periods of PWM signals Vctrl1 and Vctrl2. By changing the duty cycles of PWM signals Vctrl1 and Vctrl2, the effective value of the AC output voltage Vout can be changed, thereby achieving stepless speed regulation of motor M.

[0064] Furthermore, it also includes a signal generating circuit 600 electrically connected to the switching circuit 500. The signal generating circuit 600 obtains a PWM signal from an external source to control the alternating conduction of the third transistor Q3 and the fourth transistor Q4 in the switching circuit 500, thereby chopping the AC output voltage. Preferably, the signal generating circuit 600 is a square wave signal generating circuit.

[0065] Preferably, it also includes a low-voltage power supply circuit 700, which is electrically connected to the power supply 100 and the signal generation circuit 600 respectively, and is used to provide the required DC regulated power supply to the signal generation circuit 600.

[0066] like Figure 3 As shown, in another embodiment of the present invention, an adjustable resistor RV is connected to the motor drive module. By changing the resistance value of the adjustable resistor RV, the output voltage of the motor drive module is changed, which ultimately changes the speed of the motor M, thus achieving stepless speed regulation of the motor M. Preferably, the motor drive module uses a KM868x chip or an HT46R01C chip.

[0067] Furthermore, it also includes a second main winding L2, which is connected in series with the first main winding L1 and in parallel with the auxiliary winding L3.

[0068] Specifically, two wires are led out from the first end of the capacitor C. The first wire is connected to the second wire of the first main winding L1, and the second wire is connected to the second output terminal of the motor drive module. The second end of the capacitor C is connected to the first end of the auxiliary winding L3. Two wires are led out from the second end of the auxiliary winding L3. The first wire is connected to the second end of the second main winding L2, and the second wire is connected to the first output terminal of the motor drive module.

[0069] For example, the resistance of the first main winding L1 is S1, and the resistance of the second main winding L2 is S2. When a 220V voltage is applied to the first main winding L1, the current is 220V / S1, which is large, so the motor M rotates quickly. When a 220V voltage is applied to both the first and second main windings L1, the current is 220V / (S1+S2), which is small, so the motor M rotates slowly.

[0070] It can be seen that, due to the existence of the second main winding L2, the high speed of the stepless speed regulation circuit 300 is limited, so that the high speed of the stepless speed regulation circuit 300 is lower than the ultra-high speed of the winding tap circuit 200.

[0071] Furthermore, it also includes an input unit, which can be an operation button. The control unit is used to receive instructions from the input unit and control the tap speed regulation circuit 200 or the stepless speed regulation circuit 300 to work according to the instructions, so as to adjust the speed of the motor M.

[0072] The present invention also discloses a range hood, which includes the motor speed control device described above.

[0073] Generally, the control panel of a range hood will have multiple buttons with different speed settings to control the motor speed.

[0074] The control unit is used to control the tap speed regulation circuit 200 or the stepless speed regulation circuit 300 to operate according to the control commands generated by manual operation on the control panel, so as to adjust the speed of the motor M.

[0075] For example, the control panel of a range hood has an ultra-high speed button that offers higher rotation speed, stronger suction, and better smoke extraction than the high speed setting. Of course, it also has buttons for high speed, medium speed, and low speed.

[0076] When cooking produces a lot of fumes, it's necessary to increase the efficiency of the high-speed setting (M) of the motor to ensure the range hood's performance. In this case, manually select the ultra-high-speed setting. This setting is the highest speed setting for the motor (M), and the tap speed control circuit 200 controls the motor (M) to run at ultra-high speed, resulting in high operating efficiency and meeting user needs.

[0077] When simmering soup or cooking over low heat, and when there is less smoke, manually select the low speed setting button and use the stepless speed control circuit 300 to control the motor M to run at a low speed, so that the motor M is highly efficient when running at low speed.

[0078] The range hood of this invention employs both tap speed control and stepless speed regulation, allowing users to use a low speed setting when simmering soup or cooking, and a high or ultra-high speed setting when stir-frying, to quickly extract cooking fumes and meet the user's needs for fume extraction at different times.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. The implementation schemes in the above embodiments can also be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A motor speed regulating device, characterized in that: It includes a tapped speed control circuit and a stepless speed control circuit. The motor is connected to the power supply through the tapped speed control circuit and the stepless speed control circuit respectively. The operation of the motor is controlled by the tapped speed control circuit or the stepless speed control circuit. The tapped speed control circuit is used to control the motor to run at ultra-high speed, and the stepless speed control circuit is used to control the motor to run at high, medium and low speed. The motor includes a first main winding, an auxiliary winding connected in parallel with the first main winding, and a capacitor connected in series with the auxiliary winding. A tap position lead is connected to the first end of the first main winding, and the second end of the first main winding is electrically connected to the first end of the power supply. The tap speed control circuit includes a relay. The tap position lead is electrically connected / disconnected to the second terminal of the power supply through the relay. The normally closed terminal of the relay is electrically connected to the second terminal of the power supply, and the normally open terminal of the relay is electrically connected to the tap position lead. The control terminal of the relay is connected to a control unit that controls the operation of the relay. When the control unit issues a command to control the motor to operate at ultra-high speed, the relay is energized and closed, connecting the power supply to the circuit where the ultra-high speed tap position lead of the motor is located, and controlling the motor to operate at ultra-high speed. When the control unit does not issue a command to control the motor to operate at ultra-high speed, the relay is open, the ultra-high speed tap position lead of the motor is disconnected from the power supply, and the motor stops operating. Alternatively, the stepless speed control circuit can be used to control the motor to operate at high, medium, and low speeds. The stepless speed regulation circuit includes a motor drive module, which is connected in parallel between the motor and the power supply to control the effective value of the AC voltage supplied to the motor. A control unit is connected to the motor drive module to control the operation of the motor drive module. The motor drive module controls the speed of the motor according to the control command of the control unit. The motor also includes a second main winding, which is connected in series with the first main winding and in parallel with the auxiliary winding; the second main winding is used to limit the speed of the high-speed gear of the stepless speed regulation circuit, so that the speed of the high-speed gear of the stepless speed regulation circuit is lower than the speed of the ultra-high-speed gear of the tapped speed regulation circuit.

2. The motor speed regulating device according to claim 1, characterized in that: The tap speed control circuit also includes a thermal protector, the first end of which is connected to the second end of the first main winding, and the second end of which is connected to the power supply lead.

3. The motor speed regulating device according to claim 2, characterized in that: The thermal protector is a fuse.

4. The motor speed regulating device according to claim 1, characterized in that: The motor drive module includes a rectifier circuit and a switching circuit electrically connected to the rectifier circuit. The rectifier circuit is used to rectify the AC input voltage generated by the power supply into a pulsating DC voltage, and the switching circuit is used to convert the pulsating DC voltage into an AC output voltage.

5. The motor speed regulating device according to claim 4, characterized in that: It also includes a signal generating circuit electrically connected to the switching circuit, the signal generating circuit controlling the switching of transistors in the switching circuit to chop the AC output voltage.

6. The motor speed regulating device according to claim 5, characterized in that: It also includes a low-voltage power supply circuit, which is electrically connected to both the power supply and the signal generation circuit, and is used to provide the required DC regulated power supply to the signal generation circuit.

7. The motor speed regulating device according to any one of claims 1-6, characterized in that: It also includes an input unit, and the control unit is used to receive control commands from the input unit and control the tap speed regulation circuit or the stepless speed regulation circuit to work according to the control commands.

8. A range hood, characterized in that: Includes the motor speed control device as described in any one of claims 1-7.

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