Permanent magnet coupling for controlling flow

Abstract

This invention relates to a permanent magnet coupler for flow control, comprising: a conductor rotor, a permanent magnet rotor; a spacing adjustment mechanism configured to drive one of the conductor rotor and the permanent magnet rotor to move along the axial direction; and a control system electrically connected to the spacing adjustment mechanism. The control system includes: a main control unit; a drive circuit whose input terminal communicates with the signal output terminal of the main control unit, and whose output terminal is connected to a drive motor in the spacing adjustment mechanism; and a power conversion module configured to convert an external input power supply and provide multiple stable DC operating voltages required by various functional units within the control system. This invention, by employing a power conversion module with a three-phase rectifier bridge, can directly connect to commonly used industrial three-phase AC power and convert it into a stable DC operating voltage, providing strong power protection for the control system and exhibiting high adaptability.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic flowmeter technology, and more specifically to a permanent magnet coupler and system for controlling flow. Background Technology

[0002] Permanent magnet couplers, as devices that utilize permanent magnetic fields for non-contact torque transmission, are widely used in industrial transmission. They effectively isolate vibration, reduce noise, and provide overload protection. In applications requiring flow regulation, such as pumps and fans, the output torque of the permanent magnet coupler can be adjusted to achieve stepless speed regulation of the output shaft, thereby regulating the fluid flow rate. Traditional permanent magnet couplers typically adjust the output torque by adjusting the air gap distance between the conductor rotor and the permanent magnet rotor.

[0003] Patent CN101986104A discloses a quantitative control device for an electromagnetic flowmeter, relating to the field of electromagnetic flowmeter technology, and solving the technical problem of quantitatively controlling the flow rate of media in a pipeline. The device includes a solenoid valve, a relay, a first optocoupler, and a second optocoupler. The control signal input terminal of the microcontroller built into the electromagnetic flowmeter is connected to the positive output terminal of the first optocoupler and then connected to a positive power supply via a pull-up resistor. Its control signal output terminal is connected to the positive input terminal of the second optocoupler. The positive input terminal of the first optocoupler is connected in series with a certain number of control switches and a voltage divider resistor to the positive power supply, its negative input terminal is connected to a negative power supply, and its negative output terminal is grounded. The negative input terminal of the second optocoupler is grounded, its positive output terminal is connected to a positive power supply via another voltage divider resistor, and its negative output terminal is connected in series with the coil of the relay to ground. The solenoid valve is installed on the controlled pipeline, and its control terminal is connected in series with the relay contacts to the solenoid valve's operating power supply.

[0004] Although the above solution achieves quantitative flow control by using solenoid valves and relays, it is still based on simple switching control, and the control accuracy is greatly affected by external factors. At the same time, it cannot be directly adapted to industrial three-phase AC power supply, and lacks effective handling of power fluctuations and electromagnetic interference. Summary of the Invention

[0005] The purpose of this invention is to provide a permanent magnet coupler for controlling flow rate, aiming to solve the technical problems of poor power supply adaptability and low reliability of existing permanent magnet couplers.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention proposes a permanent magnet coupler for controlling flow rate, comprising: A conductor rotor is fixedly connected to an input shaft and is provided with an induction conductor section; A permanent magnet rotor is fixedly connected to an output shaft, is arranged axially opposite to the conductor rotor, and has multiple permanent magnets arranged circumferentially. The gap adjustment mechanism is configured to drive one of the conductor rotor and the permanent magnet rotor to move axially to steplessly adjust the air gap distance between them. And a control system, which is electrically connected to the spacing adjustment mechanism; The control system includes: The main control unit is used to pre-store the correspondence data between air gap distance and transmitted torque; The driving circuit has its input terminal communicating with the signal output terminal of the main control unit, and its output terminal connected to the drive motor in the spacing adjustment mechanism, for driving the drive motor according to the instructions of the main control unit; A power conversion module is configured to convert an external input power supply and provide multiple stable DC operating voltages required by the functional units within the control system; the power conversion module includes at least a power conversion circuit based on three-phase rectification.

[0007] Furthermore, the power conversion module includes: The rectifier unit includes a fuse F1 connected in series and a three-phase rectifier bridge. The three-phase rectifier bridge has three input terminals L1, L2, and L3 for connecting to an external three-phase AC power supply. A filter capacitor C1 is connected in parallel to the output terminal of the three-phase rectifier bridge. The inverter circuit includes MOSFETs M1, M2, M3, and M4; MOSFETs M1 and M2 are connected in series to form a first bridge arm, with their connection node being the midpoint of the first bridge arm; MOSFETs M3 and M4 are connected in series to form a second bridge arm, with their connection node being the midpoint of the second bridge arm; the first and second bridge arms are connected in parallel between the positive and negative output terminals of the rectifier unit to convert direct current into high-frequency alternating current; The resonant converter module includes an inductor L4, a capacitor C2, a transformer T1, and a diode D2. One end of the inductor L4 is connected to the midpoint of the second bridge arm, and the other end of the inductor L4 is connected to the first end of the primary winding of the transformer T1. The two ends of the inductor L4 are also connected to the diode D2. The capacitor C2 is connected to the midpoint of the second bridge arm, and the other end of the capacitor C2 is connected to the second end of the primary winding of the transformer T1. The secondary winding of the transformer T1 converts high-frequency AC power into stable DC power through diodes D4 and D5 and an output filter circuit. The control unit is connected to the inverter circuit and the resonant converter module respectively, and is used to control the operation of the inverter circuit and sample the output voltage or current of the resonant converter module for adjustment.

[0008] Furthermore, the output filter circuit includes a filter inductor L5 and a capacitor C3. The secondary winding of the transformer T1 has a center-tapped structure, with its first end connected to the cathode of diode D4. The anode of diode D4 is connected to the filter inductor L5, and the output terminal of the filter inductor L5 serves as the positive output terminal of the resonant converter module. The second end of the secondary winding is connected to the cathode of diode D5, and the anode of diode D5 is connected to the negative output terminal of the resonant converter module. The negative output terminal is grounded, and the capacitor C3 is connected between the negative output terminal and the positive output terminal.

[0009] Furthermore, diodes D1 and D3 are connected in parallel between the source and drain of MOSFETs M1, M2, M3 and M4, respectively.

[0010] Furthermore, the control unit includes a microcontroller (MCU), one end of which is connected to the gate of each MOSFET in the inverter circuit, and the other end of which is connected to the gate of a MOSFET M5. The source of the MOSFET M5 is connected to the drive circuit, and the drain of the MOSFET M5 is connected to the resonant converter module. A resistor R1 is also connected between the negative output terminal and the positive output terminal of the resonant converter module for sampling the output voltage or current.

[0011] Furthermore, the driving circuit includes a signal adjustment circuit, a PMI circuit, an operational amplifier unit U2, an operational amplifier unit U1, and a transistor Q2; the signal adjustment circuit, the PMI circuit, the operational amplifier unit U2, and the operational amplifier unit U1 are connected in sequence. In this configuration, the collector of transistor Q2 is connected to the non-inverting input of operational amplifier unit U1 via resistor R10, the emitter of transistor Q2 is grounded, and its base is connected to the anode of diode D7 via resistor R9. The cathode of diode D7 is connected to the midpoint of the first voltage divider network. The first voltage divider network consists of resistors R7 and R8 connected in series. Resistor R7 is also connected to MOSFET M5 via resistor R2. A capacitor C4 is connected in parallel across resistor R8 and then grounded. The inverting input of operational amplifier unit U1 is grounded via capacitor C6, and its output is connected to the non-inverting input of operational amplifier unit U2. The inverting input of operational amplifier unit U2 is grounded via capacitor C9, and its output is connected to the PMI circuit via capacitor C7 and diode D8 in sequence. The connection point between capacitor C7 and diode D8 is grounded via diode D9 connected in parallel. The PMI circuit is electrically connected to the signal conditioning circuit.

[0012] Furthermore, a capacitor C8 is connected in parallel between the PMI circuit and the diode D8.

[0013] Furthermore, the control system also includes a communication module, which is connected to the communication interface of the main control MCU. The communication module is an interface circuit based on RS-485 protocol or CAN bus protocol, used to receive flow setting commands from the outside.

[0014] Furthermore, the control system also includes a flow sensing unit for detecting the real-time fluid flow rate of the driven load.

[0015] Furthermore, the input shaft is connected to the drive motor, and the output shaft is connected to the impeller shaft of the pump or fan.

[0016] Compared with the prior art, the present invention 1, by adopting a power conversion module with a three-phase rectifier bridge, can directly connect to the commonly used three-phase AC power supply in industry and convert it into a stable DC working voltage, providing a strong power guarantee for the control system and having strong adaptability.

[0017] 2. The control unit is used as an independent auxiliary control circuit. The microcontroller (MCU) monitors the output status of the power conversion module and adjusts the conduction of the MOSFET M5. In conjunction with the voltage divider resistor network, it can achieve fine adjustment of the power output or shut down or limit the current under specific conditions, thereby realizing overvoltage and overcurrent protection of the power output, or realizing feedback control of specific voltage.

[0018] 3. The voltage divider resistor network provides a precise reference voltage or enables proportional scaling of the sensor signal, and effectively compensates for the voltage division ratio changes caused by resistor temperature drift through resistor R8, thereby ensuring the long-term stability and accuracy of the sampled values ​​of key parameters such as air gap distance and current.

[0019] 4. The PMI circuit in the drive circuit, combined with a filter network consisting of diodes D8 and D9 and capacitors C7 and C8, can effectively shape and suppress noise in the control signal, thereby effectively filtering out high-frequency interference from the power supply and signal lines. This ensures the purity of the signals input to the operational amplifier units U1 and U2, significantly improving electromagnetic compatibility (EMC) performance and avoiding malfunctions caused by signal noise. Furthermore, the entire drive circuit, through a feedback network connected to the emitter of the final stage transistor Q2, feeds back the output status to the front end in real time, forming a local closed-loop control. This automatically compensates for changes in drive capability caused by load variations or power fluctuations, ensuring stable output torque. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a permanent magnet coupler; Figure 2 This is the circuit structure diagram of the power conversion module excluding the control unit (i.e., the rectifier unit, inverter circuit, and resonant converter module); Figure 3This is a circuit diagram of the power conversion module and the drive circuit. Figure 4 This is the circuit structure diagram of the main control unit. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0022] See Figure 1 In one embodiment of the present invention, a permanent magnet coupler for controlling flow rate includes: A conductor rotor is fixedly connected to an input shaft and is provided with an induction conductor section; A permanent magnet rotor is fixedly connected to an output shaft and is arranged axially opposite to the conductor rotor, and has multiple permanent magnets arranged circumferentially. When the input shaft of the permanent magnet rotor drives the conductor rotor to rotate, a magnetic field is generated between the permanent magnets on the permanent magnet rotor and the induction conductor, thereby generating eddy currents on the conductor rotor. The eddy currents interact with the magnetic field of the permanent magnets to generate electromagnetic torque, which drives the permanent magnet rotor and the output shaft to rotate, realizing non-contact torque transmission. The gap adjustment mechanism is configured to drive one of the conductor rotor and the permanent magnet rotor to move axially, so as to steplessly adjust the air gap distance between them; by adjusting the air gap distance, the magnitude of the torque transmitted by the permanent magnet coupler can be linearly changed: when the air gap decreases, the transmitted torque increases; when the air gap increases, the transmitted torque decreases; wherein, the gap adjustment mechanism is usually composed of a drive motor and a corresponding mechanical transmission device, such as a lead screw, gears, etc., to achieve high-precision axial displacement; The system is electrically connected to the spacing adjustment mechanism and is used to control the flow rate of the entire permanent magnet coupler. The control system includes: The main control unit is used to pre-store the correspondence data between air gap distance and transmission torque; after the required flow rate value is determined, the main control unit calculates the required air gap distance value based on the characteristic curve of the pump or fan and in combination with the data on air gap distance and transmission torque. The drive circuit has its input end communicating with the signal output end of the main control unit, and its output end connected to the drive motor in the spacing adjustment mechanism. It is used to drive the drive motor according to the instructions of the main control unit. The drive circuit drives the drive motor to precisely adjust the air gap distance between the conductor rotor and the permanent magnet rotor according to the control instructions issued by the main control unit, thereby controlling the transmitted torque and achieving the purpose of regulating the flow rate. The power conversion module is configured to convert an external input power supply and provide multiple stable DC operating voltages required by the functional units within the control system; the power conversion module includes at least a power conversion circuit based on three-phase rectification; it is used to ensure that the permanent magnet coupler can be directly connected to the three-phase AC power supply commonly found in industrial environments, and convert it into a stable DC power supply to provide a reliable power supply for the main control unit, drive circuit and other control system components.

[0023] In this embodiment, by rigidly fixing the conductor rotor and the permanent magnet rotor to the input shaft and the output shaft respectively, and setting an axially sliding gap adjustment mechanism between them, the two rotors always maintain coaxiality when subjected to axial impact or radial vibration, thus avoiding the alignment error caused by fatigue deformation of traditional flexible couplings. On the other hand, by using a power conversion module with a three-phase rectifier circuit, it can be directly connected to the commonly used three-phase AC power supply in industry and converted into a stable DC working voltage, providing a strong power guarantee for the control system and making it highly adaptable. At the same time, the main control unit pre-stores the corresponding data of air gap distance and transmission torque. Combined with the drive circuit and the gap adjustment mechanism, it can realize precise stepless adjustment of the air gap of the permanent magnet coupler, thereby achieving precise control of torque and flow.

[0024] See Figure 2 In one embodiment of the present invention, the power conversion module includes: The rectifier unit includes a fuse F1 connected in series and a three-phase rectifier bridge. The three-phase rectifier bridge has three input terminals L1, L2, and L3 for connecting to an external three-phase AC power supply. A filter capacitor C1 is connected in parallel to the output terminal of the three-phase rectifier bridge. The inverter circuit includes MOSFETs M1, M2, M3, and M4. MOSFETs M1 and M2 are connected in series to form a first bridge arm, with their connection node being the midpoint of the first bridge arm. MOSFETs M3 and M4 are connected in series to form a second bridge arm, with their connection node being the midpoint of the second bridge arm. The first and second bridge arms are connected in parallel between the positive and negative output terminals of the rectifier unit to convert DC power into high-frequency AC power. The midpoints of the first and second bridge arms serve as output terminals, capable of outputting symmetrical high-frequency AC square wave voltages. This allows the power conversion module to efficiently and stably convert external three-phase AC power into multiple DC operating voltages required by the control system, ensuring the precise operation of core components such as the main control unit and drive circuit. This, in turn, improves the response speed and control accuracy of the permanent magnet coupler when adjusting the air gap distance and controlling the transmitted torque. The resonant converter module includes an inductor L4, a capacitor C2, a transformer T1, and a diode D2. One end of the inductor L4 is connected to the midpoint of the second bridge arm, and the other end of the inductor L4 is connected to the first end of the primary winding of the transformer T1. The two ends of the inductor L4 are also connected to the diode D2. The capacitor C2 is connected to the midpoint of the second bridge arm, and the other end of the capacitor C2 is connected to the second end of the primary winding of the transformer T1. The secondary winding of the transformer T1 converts high-frequency AC power into stable DC power through diodes D4 and D5 and an output filter circuit. Transformer T1 is used to achieve voltage step-up / step-down and isolation. The secondary winding is also connected to a reverse clamping diode D5. When transformer T1 disconnects the inductive load or a transient voltage occurs, reverse clamping diode D5 can effectively absorb the reverse electromotive force, protecting the transformer and subsequent circuits from high-voltage surges. Furthermore, through the series resonant network formed by inductor L4 and capacitor C2, the resonant current changes sinusoidally under the excitation of the square wave voltage output from the inverter circuit, achieving zero-voltage turn-on or zero-current turn-off of the switching transistor, greatly reducing switching losses and electromagnetic noise. Simultaneously, diode D2 connected in parallel across inductor L4 provides clamping protection during circuit startup or sudden load changes, preventing excessively high reverse induced electromotive force across inductor L4 and ensuring reliable operation of the resonant converter module. Transformer T1 achieves electrical isolation between input and output and voltage amplitude matching, further improving the safety and adaptability of the power conversion module.

[0025] The control unit is connected to the inverter circuit and the resonant converter module respectively, and is used to control the operation of the inverter circuit and sample the output voltage or current of the resonant converter module for adjustment.

[0026] In this embodiment, three-phase alternating current is converted into pulsating direct current, and further converted into multiple stable DC operating voltages required by the system's various functional units through an inverter circuit and a resonant converter module; the output terminal of the three-phase rectifier bridge is also connected to a transistor Q1, and the rectified output voltage can be adjusted by controlling the transistor Q1.

[0027] In the above embodiment, the output filter circuit includes a filter inductor L5 and a capacitor C3. The secondary winding of the transformer T1 has a center-tapped structure, with its first end connected to the cathode of diode D4. The anode of diode D4 is connected to the filter inductor L5, and the output terminal of the filter inductor L5 serves as the positive output terminal of the resonant converter module. The second end of the secondary winding is connected to the cathode of diode D5, and the anode of diode D5 is connected to the negative output terminal of the resonant converter module. The negative output terminal is grounded, and the capacitor C3 is connected between the negative output terminal and the positive output terminal. The rectifier-filter structure formed by the secondary winding and L3, D4, and D5 optimizes the efficiency and output stability of the output filter circuit, providing a more stable DC output.

[0028] Specifically, when an alternating voltage is induced in the secondary winding of transformer T1, during the positive half-cycle, the current flows through the first terminal of the secondary winding, diode D4, and filter inductor L5 to the positive output terminal, then through the load and back to the center tap of the secondary winding from the negative output terminal. During the negative half-cycle, the current flows through the second terminal of the secondary winding, diode D5, the negative output terminal, the load, then through the positive output terminal and filter inductor L5 back to the center tap of the secondary winding. This full-wave rectification structure fully utilizes both half-cycles of the transformer's secondary winding, resulting in high rectification efficiency and an output voltage ripple frequency twice the operating frequency, which is beneficial for subsequent filtering. The LC low-pass filter formed by filter inductor L5 and capacitor C3 effectively suppresses high-frequency switching noise and harmonic components, smoothing the pulsating DC voltage into a pure and stable DC current.

[0029] See Figure 2 In one embodiment of the present invention, diodes D1 and D3 are connected in parallel between the source and drain of MOSFETs M1, M2, M3 and M4, respectively. The inverter circuit uses four MOSFETs (M1-M4) to form a full-bridge topology and, in conjunction with the parallel-connected diodes D1 and D3, achieves efficient and stable DC to high-frequency AC conversion. Diodes D1 and D3 are connected in anti-parallel to the two ends of the corresponding bridge arm MOSFETs, providing a freewheeling path for the switching transistors, effectively suppressing voltage spikes during turn-off, reducing switching losses, and thus improving the efficiency and reliability of the entire power conversion circuit. Specifically, the inverter circuit includes diodes D1 and D3 connected in series. The cathode of diode D1 is connected to the junction of the source of MOSFET M1 and the drain of MOSFET M2. The cathode of diode D3 is connected to the junction of the source of MOSFET M3 and the drain of MOSFET M4. The source of MOSFET M1 is also connected to the drain of MOSFET M2. The drain of MOSFET M1 is connected to the positive output of the rectifier unit, and the source of MOSFET M2 is connected to the negative output of the rectifier unit. The source of MOSFET M3 is connected to the drain of MOSFET M4. The drain of M3 is connected to the positive output of the rectifier unit, and the source of MOSFET M4 is connected to the negative output of the rectifier unit. The midpoint of the first bridge arm is taken out as the first output terminal, and the midpoint of the second bridge arm is taken out as the second output terminal. This allows the load current of each MOSFET to continue flowing through the corresponding freewheeling diode during the turn-off period, avoiding the breakdown damage to the switching transistor caused by the induced electromotive force generated by the current change. At the same time, it realizes lossless energy feedback, further reduces electromagnetic interference, and improves the working stability and conversion efficiency of the inverter circuit in the high-frequency switching state.

[0030] See Figure 3 In one embodiment of the present invention, the control unit includes a microcontroller (MCU). One end of the MCU is connected to the gate of each MOSFET in the inverter circuit and is used to output PWM control signals to adjust the operating frequency and duty cycle of the inverter circuit. The other end of the MCU is connected to the gate of a MOSFET M5 and is used to control the output adjustment of the resonant converter module. The source of the MOSFET M5 is connected to the drive circuit to provide it with a controlled operating voltage. The drain of the MOSFET M5 is connected to the sampling circuit of the resonant converter module, and a resistor R1 is also connected between the negative output terminal and the positive output terminal of the resonant converter module to collect the output voltage or current signal in real time and feed it back to the analog input port of the MCU to form a closed-loop control.

[0031] Specifically, the secondary winding of transformer T1 is grounded via diode D4, parallel filter capacitor C3, and load resistor R1 to provide a stable DC output. For example, this output can be used to power the main control unit or other low-voltage control circuits.

[0032] Specifically, when the microcontroller (MCU) outputs a high-level signal, MOSFET M5 is turned on, enabling the drive circuit to operate normally and supply power to the drive motor in the air gap adjustment mechanism. When the MCU outputs a low-level signal, MOSFET M5 is turned off, cutting off the power supply to the drive circuit, thus achieving rapid protection under fault conditions. Based on the difference between the preset voltage reference value and the actual sampled value, the MCU dynamically adjusts the duty cycle or frequency of the PWM control signals output to each MOSFET in the inverter circuit, thereby accurately stabilizing the output voltage of the resonant converter module. This ensures that each functional unit of the control system can obtain a stable and reliable operating voltage under different load conditions, thereby improving the response speed and control accuracy of the permanent magnet coupler for air gap distance adjustment.

[0033] In this embodiment, the high-frequency AC voltage on the secondary side of the transformer can be efficiently rectified into a smooth, low-ripple DC voltage through the cooperation of the full-wave rectifier circuit and the LC filter network, providing a clean and stable power supply for the subsequent control system.

[0034] See Figure 3 In one embodiment of the present invention, the driving circuit includes a signal adjustment circuit, a PMI circuit, an operational amplifier unit U2, an operational amplifier unit U1, and a transistor Q2; the signal adjustment circuit, the PMI circuit, the operational amplifier unit U2, and the operational amplifier unit U1 are connected in sequence for precise amplification and compensation adjustment of the sampled signal; In this configuration, the collector of transistor Q2 is connected to the non-inverting input of operational amplifier unit U1 via resistor R10. The emitter of transistor Q2 is grounded, and its base is connected to the anode of diode D7 via resistor R9. The cathode of diode D7 is connected to the midpoint of the first voltage divider network. The first voltage divider network consists of resistors R7 and R8 connected in series. Resistor R7 is also connected to MOSFET M5 via resistor R2 to introduce a sampling component of the output voltage. A capacitor C4 is connected in parallel across resistor R8 and then grounded, forming a filter circuit to eliminate high-frequency noise interference. The inverting input of operational amplifier unit U1 is grounded via capacitor C6, and its output is connected to... The non-inverting input of operational amplifier unit U2 forms a two-stage amplifier circuit to provide sufficient gain and stability. The inverting input of operational amplifier unit U2 is grounded through capacitor C9, and its output is connected to the PMI circuit in sequence through capacitor C7 and diode D8. The connection node of capacitor C7 and diode D8 is grounded through diode D9 in parallel, forming a peak detection circuit to convert the AC error signal into a DC level. The PMI circuit (power management interface circuit) is electrically connected to the signal adjustment circuit and feeds back the processed error signal to the microcontroller MCU or directly participates in PWM modulation, thereby realizing high-precision closed-loop regulation of the output voltage or current.

[0035] This embodiment can monitor minute fluctuations in output voltage / current in real time and respond quickly to maintain output stability, effectively suppressing output disturbances caused by load changes or input voltage fluctuations, and further improving the purity and reliability of the power supply to the control system.

[0036] See Figure 3 In one embodiment of the present invention, a capacitor C8 is connected in parallel between the PMI circuit and the diode D8; this further effectively shapes and suppresses noise in the control signal, thereby effectively filtering out high-frequency interference from the power supply and signal lines.

[0037] In one embodiment of the present invention, the control system further includes a communication module, which is connected to the communication interface of the main control MCU. The communication module is an interface circuit based on RS-485 protocol or CAN bus protocol, used to receive flow setting instructions from the outside, so that the permanent magnet coupler can easily interact with the host computer, PLC programmable logic controller or other industrial control system to realize remote control and centralized management.

[0038] In one embodiment of the invention, the control system further includes a flow sensing unit configured to detect the real-time fluid flow rate of the driven load. The main control unit is further configured to: receive the real-time fluid flow rate through the communication module, compare it with a preset flow rate threshold, and generate control commands based on the comparison results through a closed-loop control algorithm, and operate the spacing adjustment mechanism by the drive circuit to perform closed-loop adjustment of the fluid flow rate.

[0039] Specifically, see Figure 4 The main control unit includes the main control MCU, which achieves high-precision flow conversion and monitoring by acquiring the C-phase, W-phase, and R-phase signals of the encoder EC. The C-phase signal provides a reference pulse count for flow measurement, the W-phase signal indicates the rotation direction of the flow meter to distinguish the medium flow direction, and the R-phase signal serves as a zero-point reference signal for periodic calibration of the accumulated flow. The main control MCU parses the real-time flow value from the received C / W / R signals and, based on the deviation between this flow value and a preset target value, controls the gap adjustment mechanism via the drive circuit to adjust the air gap between the conductor rotor and the permanent magnet rotor, thereby achieving stepless adjustment of the output speed and the flow rate of the driven load.

[0040] In this embodiment, the main control unit can not only receive external flow setting commands, but also obtain actual flow feedback data through the flow sensing unit, forming a closed-loop control loop. When there is a deviation between the actual flow and the set flow (preset flow threshold), the main control unit will calculate a new air gap distance adjustment command according to a closed-loop control algorithm (such as a PID control algorithm), and drive the gap adjustment mechanism to adjust until the actual flow reaches the set value, thereby greatly improving the accuracy of flow control and the anti-interference capability of the system, enabling it to better adapt to changes in external load.

[0041] In one embodiment of the invention, the input shaft is connected to a drive motor, and the output shaft is connected to the impeller shaft of a pump or fan. Since the permanent magnet coupler can steplessly adjust the transmitted torque, thereby achieving stepless adjustment of the output shaft speed, the speed of the pump or fan can be precisely controlled, thus achieving smooth and efficient control of the fluid flow rate. For example, when the drive motor runs at a constant speed, adjusting the air gap of the permanent magnet coupler can change the torque transmitted to the pump or fan, thereby changing the speed and output flow rate of the pump or fan. Combined with the closed-loop control function of the communication module, flow sensing unit, and main control unit, this fluid delivery system can achieve highly automated flow control: an externally set target flow rate, the flow sensing unit monitors the actual flow rate in real time, the main control unit compares and calculates, and then automatically adjusts the air gap of the permanent magnet coupler through the drive circuit and the gap adjustment mechanism, thereby precisely maintaining or changing the fluid flow rate.

[0042] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the invention. Modifications and variations made by those skilled in the art in accordance with the spirit of the invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A permanent magnet coupler for controlling flow rate, comprising: A conductor rotor is fixedly connected to an input shaft and is provided with an induction conductor section; A permanent magnet rotor is fixedly connected to an output shaft, is arranged axially opposite to the conductor rotor, and has multiple permanent magnets arranged circumferentially. The gap adjustment mechanism is configured to drive one of the conductor rotor and the permanent magnet rotor to move axially to steplessly adjust the air gap distance between them. And a control system, which is electrically connected to the spacing adjustment mechanism; The control system is characterized by comprising: The main control unit is used to pre-store the correspondence data between air gap distance and transmitted torque; The driving circuit has its input terminal communicating with the signal output terminal of the main control unit, and its output terminal connected to the drive motor in the spacing adjustment mechanism, for driving the drive motor according to the instructions of the main control unit; A power conversion module is configured to convert an external input power supply and provide multiple stable DC operating voltages required by the functional units within the control system; the power conversion module includes at least a power conversion circuit based on three-phase rectification.

2. A permanent magnet coupler for controlling flow rate according to claim 1, characterized in that: The power conversion module includes: The rectifier unit includes a fuse F1 connected in series and a three-phase rectifier bridge. The three-phase rectifier bridge has three input terminals L1, L2, and L3 for connecting to an external three-phase AC power supply. A filter capacitor C1 is connected in parallel to the output terminal of the three-phase rectifier bridge. The inverter circuit includes MOSFETs M1, M2, M3, and M4; MOSFETs M1 and M2 are connected in series to form a first bridge arm, with their connection node being the midpoint of the first bridge arm; MOSFETs M3 and M4 are connected in series to form a second bridge arm, with their connection node being the midpoint of the second bridge arm; the first and second bridge arms are connected in parallel between the positive and negative output terminals of the rectifier unit to convert direct current into high-frequency alternating current; The resonant converter module includes an inductor L4, a capacitor C2, a transformer T1, and a diode D2. One end of the inductor L4 is connected to the midpoint of the second bridge arm, and the other end of the inductor L4 is connected to the first end of the primary winding of the transformer T1. The two ends of the inductor L4 are also connected to the diode D2. The capacitor C2 is connected to the midpoint of the second bridge arm, and the other end of the capacitor C2 is connected to the second end of the primary winding of the transformer T1. The secondary winding of the transformer T1 converts high-frequency AC power into stable DC power through diodes D4 and D5 and an output filter circuit. The control unit is connected to the inverter circuit and the resonant converter module respectively, and is used to control the operation of the inverter circuit and sample the output voltage or current of the resonant converter module for adjustment.

3. A permanent magnet coupler for controlling flow rate according to claim 2, characterized in that: The output filtering circuit includes a filter inductor L5 and a capacitor C3. The secondary winding of the transformer T1 has a center-tapped structure. Its first end is connected to the cathode of diode D4, and the anode of diode D4 is connected to the filter inductor L5. The output end of the filter inductor L5 serves as the positive output end of the resonant converter module. The second end of the secondary winding is connected to the cathode of diode D5, and the anode of diode D5 is connected to the negative output end of the resonant converter module. The negative output end is grounded, and the capacitor C3 is connected between the negative output end and the positive output end.

4. A permanent magnet coupler for controlling flow rate according to claim 2, characterized in that: Diodes D1 and D3 are connected in parallel between the source and drain of MOSFETs M1, M2, M3 and M4, respectively.

5. A permanent magnet coupler for controlling flow rate according to claim 2, characterized in that: The control unit includes a microcontroller (MCU). One end of the MCU is connected to the gate of each MOSFET in the inverter circuit, and the other end of the MCU is connected to the gate of a MOSFET M5. The source of the MOSFET M5 is connected to the drive circuit, and the drain of the MOSFET M5 is connected to the resonant converter module. A resistor R1 is also connected between the negative output terminal and the positive output terminal of the resonant converter module for sampling the output voltage or current.

6. A permanent magnet coupler for controlling flow rate according to claim 1, characterized in that: The driving circuit includes a signal adjustment circuit, a PMI circuit, an operational amplifier unit U2, an operational amplifier unit U1, and a transistor Q2; the signal adjustment circuit, the PMI circuit, the operational amplifier unit U2, and the operational amplifier unit U1 are connected in sequence. In this configuration, the collector of transistor Q2 is connected to the non-inverting input of operational amplifier unit U1 via resistor R10, the emitter of transistor Q2 is grounded, and its base is connected to the anode of diode D7 via resistor R9. The cathode of diode D7 is connected to the midpoint of the first voltage divider network. The first voltage divider network consists of resistors R7 and R8 connected in series. Resistor R7 is also connected to MOSFET M5 via resistor R2. A capacitor C4 is connected in parallel across resistor R8 and then grounded. The inverting input of operational amplifier unit U1 is grounded via capacitor C6, and its output is connected to the non-inverting input of operational amplifier unit U2. The inverting input of operational amplifier unit U2 is grounded via capacitor C9, and its output is connected to the PMI circuit via capacitor C7 and diode D8 in sequence. The connection point between capacitor C7 and diode D8 is grounded via diode D9 connected in parallel. The PMI circuit is electrically connected to the signal conditioning circuit.

7. A permanent magnet coupler for controlling flow rate according to claim 6, characterized in that: The PMI circuit is connected in parallel with diode D8, and capacitor C8 is connected in parallel.

8. A permanent magnet coupler for controlling flow rate according to claim 1, characterized in that: The control system also includes a communication module, which is connected to the communication interface of the main control MCU. The communication module is an interface circuit based on RS-485 protocol or CAN bus protocol, used to receive flow setting commands from the outside.

9. A permanent magnet coupler for controlling flow rate according to claim 8, characterized in that: The control system also includes a flow sensing unit for detecting the real-time fluid flow rate of the driven load.

10. A permanent magnet coupler for controlling flow rate according to claim 1, characterized in that: The input shaft is connected to the drive motor, and the output shaft is connected to the impeller shaft of the pump or fan.

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