A speed-regulated motor and centrifugal pump

Abstract

The utility model relates to a kind of speed-regulating motor and centrifugal pump, and centrifugal pump includes pump shell, speed-regulating motor and impeller, impeller is connected with speed-regulating motor, and speed-regulating motor includes speed-regulating circuit, and speed-regulating circuit includes first branch and second branch in parallel, first branch includes first main winding and second main winding, first connecting end and third connecting end selectively communicate, second connecting end is selectively communicated with third connecting end and fourth connecting end respectively, to make first main winding and second main winding parallel or series connection, second branch includes auxiliary winding, first capacitor and second capacitor, one end of auxiliary winding is connected with first connecting end, the other end of auxiliary winding is connected with fifth connecting end, fourth connecting end is connected with sixth connecting end and eighth connecting end respectively, when first main winding and second main winding are in series, seventh connecting end and fifth connecting end selectively communicate.The speed-regulating mode makes the centrifugal pump above 700W produce obvious flow head difference under different rotating speeds, to meet user demand.

Description

Technical Field

[0001] This utility model relates to the field of pump technology, and in particular to a speed-regulating motor and a centrifugal pump. Background Technology

[0002] Single-phase asynchronous motors are widely used in centrifugal pumps due to their low cost and high reliability. To meet users' requirements for flow rate and head under different operating conditions, single-phase asynchronous motors need to have good speed regulation capabilities.

[0003] In existing technology, single-phase asynchronous motors include two parallel branches. One parallel branch includes a main winding, and the other parallel branch includes a capacitor and an auxiliary winding. The auxiliary winding and the capacitor are connected in series. Speed ​​regulation is achieved by adjusting the number of series-connected auxiliary windings in the parallel branch to change the total number of turns of each auxiliary winding. For example, see patent publication number CN204003546U. This speed regulation method has a good speed regulation effect in centrifugal pumps below 700W, and different speeds can produce obvious differences in flow rate and head. However, this speed regulation method is not ideal in centrifugal pumps above 700W, and different speeds cannot produce obvious differences in flow rate and head, which cannot meet the needs of users.

[0004] Therefore, there is an urgent need for a speed-regulating motor and a centrifugal pump to solve the above-mentioned technical problems. Utility Model Content

[0005] One objective of this invention is to provide a speed-regulating motor to at least solve one of the aforementioned problems.

[0006] To achieve the above objectives, this utility model provides a speed-regulating motor, including a speed-regulating circuit, wherein the speed-regulating circuit includes:

[0007] The first branch includes a first main winding and a second main winding. The first main winding has a first connecting end and a second connecting end. The second main winding has a third connecting end and a fourth connecting end. The first connecting end is selectively connected to the third connecting end. The second connecting end is selectively connected to the third connecting end and the fourth connecting end, respectively, so that the first main winding and the second main winding are connected in parallel or in series.

[0008] The second branch includes a secondary winding, a first capacitor, and a second capacitor. The first capacitor has a fifth connection terminal and a sixth connection terminal, and the second capacitor has a seventh connection terminal and an eighth connection terminal. One end of the secondary winding is connected to the first connection terminal, and the other end of the secondary winding is connected to the fifth connection terminal. The fourth connection terminal is connected to the sixth connection terminal and the eighth connection terminal respectively, so that the first branch and the second branch are connected in parallel. When the first main winding and the second main winding are connected in series, the seventh connection terminal is selectively connected to the fifth connection terminal.

[0009] Furthermore, when the speed-regulating motor is in high speed mode, the first connection terminal is connected to the third connection terminal, the second connection terminal is connected to the fourth connection terminal, the second connection terminal is disconnected from the third connection terminal, and the fifth connection terminal is disconnected from the seventh connection terminal.

[0010] Furthermore, when the speed-regulating motor is in the medium speed range, the first connection terminal is disconnected from the third connection terminal, the second connection terminal is disconnected from the fourth connection terminal, the second connection terminal is connected to the third connection terminal, and the fifth connection terminal is connected to the seventh connection terminal.

[0011] Furthermore, when the speed-regulating motor is in low speed mode, the first connection terminal is disconnected from the third connection terminal, the second connection terminal is disconnected from the fourth connection terminal, the second connection terminal is connected to the third connection terminal, and the fifth connection terminal is disconnected from the seventh connection terminal.

[0012] Furthermore, the speed control circuit also includes a thermal protector configured to be located between the live wire of the single-phase power supply and the connection point between the first connection terminal and the auxiliary winding.

[0013] Another objective of this invention is to provide a centrifugal pump to at least solve one of the aforementioned problems.

[0014] To achieve the above objectives, this utility model provides a centrifugal pump, comprising:

[0015] Pump casing;

[0016] The speed-regulating motor described in any of the above embodiments is located inside the pump casing;

[0017] The impeller is connected to the speed-regulating motor.

[0018] Furthermore, the speed control circuit also includes a first switch, a second switch, a third switch, and a fourth switch. The first connection terminal and the third connection terminal are selectively connected through the first switch, the second connection terminal and the third connection terminal are selectively connected through the second switch, the second connection terminal and the fourth connection terminal are selectively connected through the third switch, and the seventh connection terminal and the fifth connection terminal are selectively connected through the fourth switch.

[0019] Furthermore, the centrifugal pump also includes a flow detection element, which is disposed inside the pump casing.

[0020] Furthermore, the centrifugal pump also includes a processor, which is connected to the flow detection element and is connected to the first switch, the second switch, the third switch, and the fourth switch, respectively.

[0021] Furthermore, the first switch, the second switch, the third switch, and the fourth switch are all relays.

[0022] The beneficial effects of this utility model are as follows:

[0023] The centrifugal pump provided by this utility model includes a pump casing, a speed-regulating motor, and an impeller. The speed-regulating motor is located inside the pump casing, and the impeller is connected to the speed-regulating motor. The speed-regulating motor includes a speed-regulating circuit, which can adjust the speed of the speed-regulating motor, thereby adjusting the speed of the impeller, and thus changing the flow rate of the centrifugal pump to meet the user's different flow rate requirements. The speed control circuit includes a first branch and a second branch. The first branch includes a first main winding and a second main winding. The first main winding has a first connection terminal and a second connection terminal. The second main winding has a third connection terminal and a fourth connection terminal. The first connection terminal and the third connection terminal are selectively connected. The second connection terminal is selectively connected to both the third and fourth connection terminals, so that the first and second main windings are connected in parallel or in series. The second branch includes a secondary winding, a first capacitor, and a second capacitor. The first capacitor has a fifth connection terminal and a sixth connection terminal. The second capacitor has a seventh connection terminal and an eighth connection terminal. One end of the secondary winding is connected to the first connection terminal, and the other end of the secondary winding is connected to the fifth connection terminal. The fourth connection terminal is connected to both the sixth and eighth connection terminals, so that the first and second branches are connected in parallel. When the first and second main windings are connected in series, the seventh connection terminal is selectively connected to the fifth connection terminal. The speed of the speed-regulating motor is adjusted by switching the connection between the first and third connection terminals, the second and third connection terminals, the second and fourth connection terminals, and the seventh and fifth connection terminals. The speed regulation method of the speed-regulating motor provided by this utility model enables centrifugal pumps of 700W and above to have good speed regulation effect, and can produce obvious differences in flow rate and head at different speeds, so as to meet the user's requirements for flow rate and head of centrifugal pumps under different operating conditions. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the speed control circuit connection of the speed control motor provided in this embodiment of the utility model;

[0025] Figure 2 This is a control diagram of the speed regulating motor provided in this embodiment of the utility model;

[0026] Figure 3 This is a circuit diagram of the speed-regulating motor in high-speed mode provided in this embodiment of the utility model;

[0027] Figure 4 This is a circuit diagram of the speed-regulating motor in the medium speed range provided in this embodiment of the utility model;

[0028] Figure 5 This is a circuit diagram of the speed-regulating motor in low speed mode provided in this embodiment of the utility model;

[0029] Figure 6 This is a comparison chart of the flow-head curves obtained under the speed regulation mode of the centrifugal pump provided in this embodiment of the present invention and under the speed regulation mode of the centrifugal pump in the prior art.

[0030] In the picture:

[0031] 100. Speed ​​control circuit; 200. Flow detection device; 300. Processor; 400. Analog signal group; N1. First analog signal; N2. Second analog signal; N3. Third analog signal; N4. Fourth analog signal;

[0032] 10. First branch; L1. First main winding; 1. First connecting terminal; 2. Second connecting terminal; L2. Second main winding; 3. Third connecting terminal; 4. Fourth connecting terminal;

[0033] 20. Second branch; Lm. Secondary winding; C1. First capacitor; 5. Fifth connection terminal; 6. Sixth connection terminal; C2. Second capacitor; 7. Seventh connection terminal; 8. Eighth connection terminal;

[0034] 30. Single-phase power supply; L, live wire; N, neutral wire;

[0035] KH, thermal protector;

[0036] K1, first switch; K2, second switch; K3, third switch; K4, fourth switch. Detailed Implementation

[0037] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining this utility model and not for limiting it. Furthermore, it should be noted that, for ease of description, only the parts related to this utility model are shown in the accompanying drawings, not all of them.

[0038] This utility model defines certain directional terms. Unless otherwise stated, the directional terms used, such as "up", "down", "left", "right", "inner", and "outer", are used for ease of understanding and therefore do not constitute a limitation on the scope of protection of this utility model.

[0039] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0041] like Figures 1-5 As shown, this embodiment provides a centrifugal pump, which includes a pump casing, a speed-regulating motor, and an impeller. The speed-regulating motor is located inside the pump casing, and the impeller is connected to the speed-regulating motor. The speed-regulating motor is externally connected to a single-phase power supply 30. The speed-regulating motor includes a speed-regulating circuit 100, which can adjust the speed of the speed-regulating motor, thereby adjusting the speed of the impeller, and thus changing the flow rate of the centrifugal pump to meet the user's different flow rate requirements.

[0042] The speed control circuit 100 includes a first branch 10 and a second branch 20. The first branch 10 includes a first main winding L1 and a second main winding L2. The first main winding L1 has a first connecting terminal 1 and a second connecting terminal 2. The second main winding L2 has a third connecting terminal 3 and a fourth connecting terminal 4. The first connecting terminal 1 and the third connecting terminal 3 are selectively connected. The second connecting terminal 2 is selectively connected to the third connecting terminal 3 and the fourth connecting terminal 4, respectively, so that the first main winding L1 and the second main winding L2 are connected in parallel or in series. The second branch 20 includes a secondary winding L1. The system comprises a first capacitor C1 and a second capacitor C2. The first capacitor C1 has a fifth connection terminal 5 and a sixth connection terminal 6, and the second capacitor C2 has a seventh connection terminal 7 and an eighth connection terminal 8. One end of the auxiliary winding Lm is connected to the first connection terminal 1, and the other end of the auxiliary winding Lm is connected to the fifth connection terminal 5. The fourth connection terminal 4 is connected to both the sixth connection terminal 6 and the eighth connection terminal 8, so that the first branch 10 and the second branch 20 are connected in parallel. When the first main winding L1 and the second main winding L2 are connected in series, the seventh connection terminal 7 and the fifth connection terminal 5 are selectively connected. The speed of the speed-regulating motor is adjusted by switching the connection between the first connection terminal 1 and the third connection terminal 3, the second connection terminal 2 and the third connection terminal 3, the second connection terminal 2 and the fourth connection terminal 4, and the seventh connection terminal 7 and the fifth connection terminal 5. This invention provides a speed-regulating motor that enables centrifugal pumps of 700W and above to have good speed regulation effects, producing significant differences in flow rate and head at different speeds to meet users' requirements for flow rate and head under different operating conditions.

[0043] Furthermore, the single-phase power supply 30 connected to the speed-regulating motor has a live wire L and a neutral wire N. The first branch 10 and the second branch 20 are connected in parallel and then connected between the live wire L and the neutral wire N. Specifically, one end of the auxiliary winding Lm is also connected to the live wire L, and the fourth connection terminal 4 is also connected to the neutral wire N.

[0044] like Figure 1 As shown, since the single-phase power supply 30 cannot generate a rotating magnetic field, a second branch 20, an auxiliary winding Lm, and a capacitor need to be added to the stator based on the first branch 10 where the main winding is located. The first branch 10 generates a torque current, and the capacitor is connected in series with the auxiliary winding Lm in the second branch 20 to generate an excitation current. The capacitor creates a phase difference between the first branch 10 and the second branch 20, allowing the speed-regulating motor, which is a single-phase asynchronous motor, to obtain an elliptical rotating magnetic field, thereby driving the rotor to rotate. In other words, the first branch 10 is used as the main stator winding to generate a pulsating magnetic field, and the second branch 20 is used as the starting circuit. Specifically, when the phase difference between the first branch 10 and the second branch 20 is 90°, the elliptical rotating magnetic field obtained by the speed-regulating motor is more ideal.

[0045] Furthermore, the different connection methods between the different connection terminals in the first branch 10 result in different connection methods for the first main winding L1 and the second main winding L2. When the first connection terminal 1 is connected to the third connection terminal 3, the second connection terminal 2 is connected to the fourth connection terminal 4, and the second connection terminal 2 is disconnected from the third connection terminal 3, the first main winding L1 and the second main winding L2 are connected in parallel. When the first connection terminal 1 is disconnected from the third connection terminal 3, the second connection terminal 2 is disconnected from the fourth connection terminal 4, and the second connection terminal 2 is connected to the third connection terminal 3, the first main winding L1 and the second main winding L2 are connected in parallel. The parallel connection of the first main winding L1 and the second main winding L2 is equivalent to adjusting the total number of turns of the main windings in the first branch 10, which has a significant impact on the load capacity, optimal performance point, overload capacity, and starting capacity of the speed-regulating motor. Designing the main winding in the first branch 10 as multiple windings creates conditions for selective series and parallel connection between multiple windings, which can realize the change of the operating state of the speed-regulating motor and broaden the optimal performance range, output width, overload capacity and starting capacity of the speed-regulating motor.

[0046] When the first main winding L1 and the second main winding L2 are connected in parallel, it is equivalent to reducing the total number of turns of the main winding in the first branch 10. With other parameters remaining unchanged, the impedance decreases, the inductance decreases, the current increases, the magnetic flux increases, and the electromagnetic strength increases, thereby indirectly increasing the speed. When the first main winding L1 and the second main winding L2 are connected in series, it is equivalent to increasing the total number of turns of the main winding in the first branch 10. With other parameters remaining unchanged, the impedance increases, the inductance increases, the current decreases, the magnetic flux decreases, and the electromagnetic strength decreases, thereby tending to indirectly decrease the speed.

[0047] Furthermore, the connection or disconnection between the seventh connection terminal 7 and the fifth connection terminal 5 determines the number of capacitors introduced into the second branch 20. When the seventh connection terminal 7 and the fifth connection terminal 5 are connected, two capacitors are introduced into the second branch 20, namely the first capacitor C1 and the second capacitor C2. The first capacitor C1 and the second capacitor C2 are connected in parallel and then in series with the auxiliary winding Lm. When the seventh connection terminal 7 and the fifth connection terminal 5 are disconnected, only the first capacitor C1 is introduced into the second branch 20. The first capacitor C1 is directly connected in series with the auxiliary winding Lm. The parallel connection of the first capacitor C1 and the second capacitor C2 increases the total capacitance, decreases the capacitive reactance, increases the current, increases the magnetic flux of the rotating magnetic field, and increases the electromagnetic intensity, thus tending to indirectly increase the speed. The magnetic field strength of the speed-regulating motor is jointly determined by the main winding and the auxiliary winding Lm in the first branch 10 and the second branch 20. However, the main winding plays a dominant role, that is, the effect of the main winding is greater than the effect of the auxiliary winding Lm.

[0048] Furthermore, the speed control circuit 100 also includes a thermal protector KH, which is located between the live wire L and the connection point between the first connection terminal 1 and the auxiliary winding Lm. The thermal protector KH enables overload protection of the speed-regulating motor, improving the safety of its operation.

[0049] In this embodiment, the thermal protector KH is a thermal protection relay.

[0050] like Figure 2 As shown, the centrifugal pump also includes a flow detection element 200, which is located inside the pump casing and is used to detect the flow rate inside the centrifugal pump.

[0051] In this embodiment, the flow detection element 200 can be installed at the outlet or inlet of the pump casing to detect the flow rate at the outlet or inlet of the centrifugal pump.

[0052] Specifically, the flow detection element 200 can be a flow sensor, and the specific model of the flow sensor can be DJ-HS10TA.

[0053] Furthermore, the speed control circuit 100 also includes a first switch K1, a second switch K2, a third switch K3, and a fourth switch K4. The first connection terminal 1 and the third connection terminal 3 are selectively connected through the first switch K1, the second connection terminal 2 and the third connection terminal 3 are selectively connected through the second switch K2, the second connection terminal 2 and the fourth connection terminal 4 are selectively connected through the third switch K3, and the seventh connection terminal 7 and the fifth connection terminal 5 are selectively connected through the fourth switch K4.

[0054] In this embodiment, the first switch K1, the second switch K2, the third switch K3, and the fourth switch K4 can all be relays, and the relay model can be R-D1069 (5A 250VAC), used to control the on / off state between the two connection terminals.

[0055] Furthermore, the centrifugal pump also includes a processor 300, which is connected to the flow detection element 200. The processor 300 is also connected to a first switch K1, a second switch K2, a third switch K3, and a fourth switch K4. The processor 300 can automatically adjust the speed of the centrifugal pump according to the real-time flow rate inside the pump casing detected by the flow detection element 200. Specifically, the automatic switching of speed ranges can be achieved by issuing on / off commands to the first switch K1, the second switch K2, the third switch K3, and the fourth switch K4.

[0056] Specifically, the processor 300 automatically determines the speed setting of the centrifugal pump based on the real-time flow rate inside the pump casing detected by the flow detection device 200, and converts it into an analog signal group 400 as signal commands sent to the first switch K1, the second switch K2, the third switch K3, and the fourth switch K4. The analog signal group 400 includes a first analog signal N1, a second analog signal N2, a third analog signal N3, and a fourth analog signal N4. The first analog signal N1 controls the on / off state of the first switch K1, the second analog signal N2 controls the on / off state of the second switch K2, the third analog signal N3 controls the on / off state of the third switch K3, and the fourth analog signal N4 controls the on / off state of the fourth switch K4. In the analog signals, 0 represents disconnection and 1 represents connection.

[0057] The centrifugal pump provided in this embodiment has four operating states: high speed, medium speed, low speed, and automatic. The centrifugal pump can be set to high speed, medium speed, or low speed, or it can be set to automatic mode. When the centrifugal pump is in automatic mode, the processor 300 inside the centrifugal pump can automatically adjust the speed based on the real-time flow detected by the flow sensor 200.

[0058] like Figure 3 As shown, when the speed-regulating motor is in high-speed mode, the first connection terminal 1 is connected to the third connection terminal 3, the second connection terminal 2 is connected to the fourth connection terminal 4, the second connection terminal 2 is disconnected from the third connection terminal 3, and the fifth connection terminal 5 is disconnected from the seventh connection terminal 7. That is to say, in the first branch 10, the first main winding L1 and the second main winding L2 are connected in parallel, and only the first capacitor C1 is introduced in the second branch 20. Correspondingly, when the centrifugal pump is in automatic mode, if it automatically switches to high-speed mode according to the flow rate, the analog signal group 400 (N1, N2, N3, N4) is fixed at the value of (1, 0, 1, 0).

[0059] like Figure 4 As shown, when the speed-regulating motor is in the medium speed range, the first connection terminal 1 is disconnected from the third connection terminal 3, the second connection terminal 2 is disconnected from the fourth connection terminal 4, the second connection terminal 2 is connected to the third connection terminal 3, and the fifth connection terminal 5 is connected to the seventh connection terminal 7. That is, in the first branch 10, the first main winding L1 and the second main winding L2 are connected in series, and in the second branch 20, the first capacitor C1 and the second capacitor C2 are introduced, and the first capacitor C1 and the second capacitor C2 are connected in parallel. Correspondingly, when the centrifugal pump is in the automatic mode, if it switches to the medium speed range according to the flow rate, the analog signal group 400 (N1, N2, N3, N4) is fixed at the value (0, 1, 0, 1).

[0060] like Figure 5As shown, when the speed-regulating motor is in low speed mode, the first connection terminal 1 is disconnected from the third connection terminal 3, the second connection terminal 2 is disconnected from the fourth connection terminal 4, the second connection terminal 2 is connected to the third connection terminal 3, and the fifth connection terminal 5 is disconnected from the seventh connection terminal 7. That is, in the first branch 10, the first main winding L1 and the second main winding L2 are connected in series, and only the first capacitor C1 is introduced into the second branch 20. Correspondingly, when the centrifugal pump is in automatic mode, if it switches to low speed mode according to the flow rate, the analog signal group 400 (N1, N2, N3, N4) is fixed at the value (0, 1, 0, 0).

[0061] When the centrifugal pump is set to automatic mode, the maximum flow rate of the centrifugal pump is defined as Qmax. The maximum flow rate satisfied by the low-speed mode is Q1, and the maximum flow rate satisfied by the medium-speed mode is Q2. If the real-time flow rate Q detected by the flow sensor 200 satisfies 0≤Q≤Q1, the analog signal group 400 (N1, N2, N3, N4) is automatically fixed at the value of (0, 1, 0, 0), that is, the centrifugal pump automatically switches to low-speed mode. If the real-time flow rate Q detected by the flow sensor 200 satisfies Q1<Q≤Q2, the analog signal group 400 (N1, N2, N3, N4) is automatically fixed at the value of (0, 1, 0, 1), that is, the centrifugal pump automatically switches to medium-speed mode. If the real-time flow rate Q detected by the flow sensor 200 satisfies Q2<Q≤Qmax, the analog signal group 400 (N1, N2, N3, N4) is automatically fixed at the value of (1, 0, 1, 0), that is, the centrifugal pump automatically switches to high-speed mode.

[0062] In automatic mode, the centrifugal pump provided in this embodiment can automatically switch to the appropriate gear according to the real-time operating flow rate, ensuring that the centrifugal pump is always in a high-efficiency and energy-saving operating state.

[0063] Figure 6 This is a comparison chart of the flow-head curves obtained under the speed regulation mode of the centrifugal pump provided in this embodiment and under the speed regulation mode of a centrifugal pump in the prior art. The rated power of the centrifugal pump is 1000W under both speed regulation modes. The speed regulation mode in the prior art refers to the speed regulation mode mentioned in the background art. The centrifugal pump provided in this embodiment is set to automatic mode. Figure 6 As shown, compared with the speed regulation method of centrifugal pumps in the prior art, the speed regulation method of the centrifugal pump provided in this embodiment makes the difference in flow rate and head of the centrifugal pump more obvious in the high speed, medium speed and low speed ranges, so as to verify that the speed regulation performance of the centrifugal pump provided in this embodiment is superior.

[0064] It should be noted that the values ​​of Qmax, Q1, and Q2 for centrifugal pumps under different parameters vary in high-speed, medium-speed, and low-speed settings, and can be set according to actual conditions. In this embodiment, when the rated power of the centrifugal pump is 1000W, Q1 = 4000 l / h, Q2 = 8000 l / h, and Qmax = 12000 l / h. Of course, these values ​​are not limited to the above values; the values ​​provided in this embodiment are merely examples.

[0065] Compared to simply changing the number of turns in the secondary winding Lm, the speed regulation method of the speed-regulating motor provided in this embodiment, which changes the number of turns in the main windings of the first branch 10 by altering the connection method of the first main winding L1 and the second main winding L2, more easily changes the magnetic field strength to change the speed, and the speed difference between different gears is greater. Furthermore, in this embodiment, the first main winding L1 and the second main winding L2 in the first branch 10 are always in use, resulting in higher winding utilization and efficiency for the first main winding L1 and the second main winding L2.

[0066] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A speed-regulating motor, characterized in that, Includes a speed control circuit (100), the speed control circuit (100) comprising: The first branch (10) includes a first main winding (L1) and a second main winding (L2). The first main winding (L1) has a first connecting end (1) and a second connecting end (2). The second main winding (L2) has a third connecting end (3) and a fourth connecting end (4). The first connecting end (1) is selectively connected to the third connecting end (3). The second connecting end (2) is selectively connected to the third connecting end (3) and the fourth connecting end (4) respectively, so that the first main winding (L1) and the second main winding (L2) are connected in parallel or in series. The second branch (20) includes a secondary winding (Lm), a first capacitor (C1), and a second capacitor (C2). The first capacitor (C1) has a fifth connection terminal (5) and a sixth connection terminal (6). The second capacitor (C2) has a seventh connection terminal (7) and an eighth connection terminal (8). One end of the secondary winding (Lm) is connected to the first connection terminal (1), and the other end of the secondary winding (Lm) is connected to the fifth connection terminal (5). The fourth connection terminal (4) is connected to the sixth connection terminal (6) and the eighth connection terminal (8) respectively, so that the first branch (10) and the second branch (20) are connected in parallel. When the first main winding (L1) and the second main winding (L2) are connected in series, the seventh connection terminal (7) is selectively connected to the fifth connection terminal (5).

2. The speed-regulating motor according to claim 1, characterized in that, When the speed-regulating motor is in high speed, the first connection end (1) is connected to the third connection end (3), the second connection end (2) is connected to the fourth connection end (4), the second connection end (2) is disconnected from the third connection end (3), and the fifth connection end (5) is disconnected from the seventh connection end (7).

3. The speed-regulating motor according to claim 1, characterized in that, When the speed-regulating motor is in the medium speed range, the first connection end (1) is disconnected from the third connection end (3), the second connection end (2) is disconnected from the fourth connection end (4), the second connection end (2) is connected to the third connection end (3), and the fifth connection end (5) is connected to the seventh connection end (7).

4. The speed-regulating motor according to claim 1, characterized in that, When the speed-regulating motor is in low speed, the first connection end (1) is disconnected from the third connection end (3), the second connection end (2) is disconnected from the fourth connection end (4), the second connection end (2) is connected to the third connection end (3), and the fifth connection end (5) is disconnected from the seventh connection end (7).

5. The speed-regulating motor according to claim 1, characterized in that, The speed control circuit (100) further includes a thermal protector (KH), which is configured to be located between the live wire (L) of the single-phase power supply (30) and the connection point between the first connection terminal (1) and the secondary winding (Lm).

6. A centrifugal pump, characterized in that, include: Pump casing; The speed-regulating motor as described in any one of claims 1-5 is disposed within the pump casing; The impeller is connected to the speed-regulating motor.

7. The centrifugal pump according to claim 6, characterized in that, The speed control circuit (100) further includes a first switch (K1), a second switch (K2), a third switch (K3), and a fourth switch (K4). The first connection terminal (1) and the third connection terminal (3) are selectively connected through the first switch (K1). The second connection terminal (2) and the third connection terminal (3) are selectively connected through the second switch (K2). The second connection terminal (2) and the fourth connection terminal (4) are selectively connected through the third switch (K3). The seventh connection terminal (7) and the fifth connection terminal (5) are selectively connected through the fourth switch (K4).

8. The centrifugal pump according to claim 7, characterized in that, The centrifugal pump also includes a flow detection element (200), which is disposed inside the pump casing.

9. The centrifugal pump according to claim 8, characterized in that, The centrifugal pump also includes a processor (300), which is connected to the flow detection element (200) and is connected to the first switch (K1), the second switch (K2), the third switch (K3) and the fourth switch (K4) respectively.

10. The centrifugal pump according to claim 7, characterized in that, The first switch (K1), the second switch (K2), the third switch (K3), and the fourth switch (K4) are all relays.

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