Variable frequency drive circuit of pump motor

Abstract

The utility model relates to a variable frequency drive circuit of a pump motor. The variable frequency drive circuit comprises a rectifier transformer, a direct current conversion module, a power management module, an OR gate, an MCU, a gate drive module, a motor drive module, a voltage sensor, a Schmitt trigger and a phase inverter, a pump motor is selected as a three-phase direct-current motor, high-low level pulses output by an MCU are used for controlling a grid driving module to output grid control pulses so as to drive a motor driving module to output phase driving voltage, and three phases of the pump motor are controlled by the phase driving voltage output by the driving module to adjust the rotating speed of the pump motor; meanwhile, an OR gate control circuit is additionally arranged in front of a pre-driven enable signal, the circuit is controlled by output signals of the MCU and the voltage sensor, and the MCU or the Schmitt trigger outputs a low-level control signal so that the pre-driven pump motor can be closed to enter a safe state.

Description

Technical Field

[0001] This utility model relates to the field of water pump control technology, specifically to a pump motor frequency conversion drive circuit. Background Technology

[0002] When driving a water pump, an AC motor is usually used. When it is necessary to change the speed of the pump motor, the driving voltage of the AC motor is changed to change the motor speed. However, when more precise control of the motor speed is required, the control accuracy of the AC motor is not as good as that of the DC motor.

[0003] However, more precise control of the pump motor speed is required, necessitating the use of a DC motor to replace the traditional pump motor. However, the traditional pump motor control method, which changes the supply voltage by altering the resistance value, also cannot meet the demands of high-precision pump motor speed control. Utility Model Content

[0004] To address the technical problem that the traditional pump motor control method, which uses the resistance value to change the power supply voltage, cannot meet the requirements for high-precision pump motor speed control, this utility model provides a pump motor frequency conversion drive circuit.

[0005] The technical solution of this utility model to solve the above-mentioned technical problems is as follows:

[0006] A pump motor frequency conversion drive circuit includes a rectifier transformer, a DC-DC conversion module, a power management module, an OR gate, an MCU, a gate drive module, a motor drive module, a voltage sensor, and a Schmitt trigger.

[0007] The input terminal of the rectifier transformer is connected to the mains power, and the output terminal of the rectifier transformer is electrically connected to the input terminal of the DC-DC converter module, the input terminal of the voltage sensor, the power input terminal of the gate drive module, and the power input terminal of the motor drive module, respectively; the output terminal of the DC-DC converter module is electrically connected to the input terminal of the power management module, and the voltage regulation output terminal of the power management module is electrically connected to the power input terminal of the MCU.

[0008] The voltage sensor's ground terminal is grounded; the voltage sensor's output terminal is electrically connected to the Schmitt trigger's input terminal; the Schmitt trigger's output terminal is electrically connected to one input terminal of the OR gate; the MCU's control output terminal is electrically connected to the other input terminal of the OR gate; the OR gate's output terminal is electrically connected to the gate drive module's enable control terminal; the MCU's serial communication terminal is electrically connected to the gate drive module's control input terminal; the gate drive module's drive output terminal is electrically connected to the motor drive module's control terminal; and the motor drive module's phase drive output terminal is electrically connected to the pump motor's power input terminal; wherein, the pump motor is a three-phase DC motor.

[0009] The beneficial effects of this invention are as follows: By selecting a three-phase DC motor as the pump motor, the high and low level pulses output by the MCU control the gate drive module to output gate control pulses, which in turn drive the motor drive module to output phase drive voltage. The three phases of the pump motor are controlled by the phase drive voltage output by the drive module to achieve speed regulation. Therefore, by changing the frequency of the high and low level pulses output by the MCU, the speed of the pump motor can be regulated. Compared with the traditional method of adjusting the pump motor speed by adjusting the resistor, this invention provides more precise speed control. By adding an OR gate control circuit before the enable signal of the pre-drive, which is controlled by the output signals of the MCU and the voltage sensor respectively, a low-level control signal output by the MCU or Schmitt trigger can disable the pre-drive, allowing the pump motor to enter a safe state.

[0010] Based on the above technical solution, the present invention can be further improved as follows.

[0011] Furthermore, it also includes a CAN communication module, the transceiver of which is electrically connected to the transceiver of the MCU.

[0012] The beneficial effect of adopting the above-mentioned further solution is that by setting up a CAN communication module, it is possible to communicate with the outside world through the CAN communication protocol, so as to realize the sending and receiving of information.

[0013] Furthermore, the DC-DC conversion module is a 48V to 12V power supply chip; the power management module uses a power management chip of model A4412; and the gate drive module uses a MOSFET driver of model AMT49101.

[0014] Furthermore, the motor drive module includes a first MOSFET, a second MOSFET, a third MOSFET, a fourth MOSFET, a fifth MOSFET, a sixth MOSFET, a first resistor, a second resistor, and a third resistor;

[0015] The drive output terminal of the gate drive module is electrically connected to the gate of the first MOS transistor, the gate of the second MOS transistor, the gate of the third MOS transistor, the gate of the fourth MOS transistor, the gate of the fifth MOS transistor, and the gate of the sixth MOS transistor, respectively.

[0016] The output terminal of the rectifier transformer is electrically connected to the drain of the first MOSFET, the drain of the third MOSFET, and the drain of the fifth MOSFET, respectively. The source of the first MOSFET is electrically connected to the drain of the fourth MOSFET. The source of the fourth MOSFET is electrically connected to one end of the first resistor, and the other end of the first resistor is grounded. The source of the sixth MOSFET is electrically connected to one end of the second resistor, and the other end of the second resistor is grounded. The source of the second MOSFET is electrically connected to one end of the third resistor, and the other end of the third resistor is grounded.

[0017] The three-phase power supply terminals of the pump motor are electrically connected to the source of the first MOS transistor, the source of the third MOS transistor, and the source of the fifth MOS transistor, respectively.

[0018] Furthermore, the motor drive module also includes a seventh MOS transistor, the gate of which is electrically connected to the drive output terminal of the gate drive module, the drain of which is electrically connected to the output terminal of the rectifier transformer, and the source of which is electrically connected to the drain of the first MOS transistor, the drain of the third MOS transistor, and the drain of the fifth MOS transistor.

[0019] Furthermore, it also includes an emergency stop switch, one end of which is electrically connected to the output terminal of the rectifier transformer, and the other end of which is electrically connected to the drain of the seventh MOSFET.

[0020] The beneficial effect of adopting the above-mentioned further solution is that by setting an emergency stop switch, the power supply to the motor drive module can be cut off after pressing the emergency stop switch in an emergency, thereby improving the safe working performance of the pump motor.

[0021] Furthermore, it also includes a manual switch, one end of which is electrically connected to the other end of the emergency stop switch, and the other end of which is electrically connected to the drain of the seventh MOS transistor.

[0022] The advantage of adopting the above-mentioned further solution is that, by providing a manual switch, the power supply to the motor drive module can be cut off when needed.

[0023] Furthermore, the voltage sensor includes a fourth resistor and a fifth resistor. One end of the fourth resistor is electrically connected to the output terminal of the rectifier transformer, the other end of the fourth resistor is electrically connected to one end of the fifth resistor, the other end of the fifth resistor is grounded, and one end of the fifth resistor is electrically connected to the input terminal of the Schmitt trigger.

[0024] Furthermore, it also includes a filtering module, wherein the output terminal of the rectifier transformer is electrically connected to one end of the filtering module, and the other end of the filtering module is grounded.

[0025] Furthermore, the filtering module includes a first capacitor and a second capacitor, and the output terminal of the rectifier transformer is grounded to the other end of the first capacitor and the other end of the second capacitor, respectively.

[0026] The beneficial effect of adopting the above-mentioned further solution is that, by setting up a capacitor filter module, AC noise at the output of the rectifier transformer can be filtered out. Attached Figure Description

[0027] Figure 1 This is the circuit schematic diagram of this utility model;

[0028] Figure 2 This is the circuit diagram of the motor drive module;

[0029] Figure 3 This is a circuit diagram of a voltage sensor.

[0030] The attached diagram lists the components represented by each number as follows:

[0031] 1. Rectifier transformer; 2. DC-DC converter module; 3. Power management module; 4. OR gate; 5. MCU; 6. Gate driver module; 7. Motor driver module; 8. CAN communication module; 9. Voltage sensor; 10. Schmitt trigger; 11. Filtering module. Detailed Implementation

[0032] The principles and features of this utility model are described below with reference to the accompanying drawings. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0033] like Figure 1As shown, this embodiment provides a pump motor frequency conversion drive circuit, including a rectifier transformer 1, a DC-DC conversion module 2, a power management module 3, an OR gate 4, an MCU 5, a gate drive module 6, a motor drive module 7, a voltage sensor 9, and a Schmitt trigger 10; the rectifier transformer 1 is preferably a 220V AC to 48V DC transformer, the DC-DC conversion module 2 is a 48V to 12V power chip; the power management module 3 is a power management chip of model A4412; and the gate drive module 6 is a MOSFET driver of model AMT49101.

[0034] The input terminal of the rectifier transformer 1 is connected to the mains power, and the output terminal of the rectifier transformer 1 is electrically connected to the input terminal of the DC-DC converter module 2, the input terminal of the voltage sensor 9, the power input terminal of the gate drive module 6, and the power input terminal of the motor drive module 7, respectively; the output terminal of the DC-DC converter module 2 is electrically connected to the input terminal of the power management module 3, and the voltage regulation output terminal of the power management module 3 is electrically connected to the power input terminal of the MCU 5.

[0035] The ground terminal of the voltage sensor 9 is grounded. The output terminal of the voltage sensor 9 is electrically connected to the input terminal of the Schmitt trigger 10. The output terminal of the Schmitt trigger 10 is electrically connected to one of the input terminals of the OR gate 4. The control output terminal of the MCU 5 is electrically connected to the other input terminal of the OR gate 4. The output terminal of the OR gate 4 is electrically connected to the enable control terminal of the gate drive module 6. The serial communication terminal of the MCU 5 is electrically connected to the control input terminal of the gate drive module 6. The drive output terminal of the gate drive module 6 is electrically connected to the control terminal of the motor drive module 7. The phase drive output terminal of the motor drive module 7 is electrically connected to the power input terminal of the pump motor. The pump motor is a three-phase DC motor.

[0036] By selecting a three-phase DC motor as the pump motor, the high and low level pulses output by the MCU control the gate drive module 6 to output gate control pulses, which in turn drive the motor drive module 7 to output phase drive voltage. The three phases of the pump motor are controlled by the phase drive voltage output by the drive module 7 to achieve speed regulation. Therefore, by changing the frequency of the high and low level pulses output by the MCU, the speed of the pump motor can be regulated. Compared with the traditional method of adjusting the pump motor speed by adjusting the resistor, this invention provides more precise speed control. An OR gate control circuit is added before the enable signal of the pre-drive. This circuit is controlled by the output signals of the MCU and the voltage sensor. A low-level control signal output by either the MCU or the Schmitt trigger 10 can disable the pre-drive, allowing the pump motor to enter a safe state. When the output voltage of the voltage sensor 9 is lower than a preset voltage threshold, it indicates that the output voltage of the rectifier transformer 1 is too low to meet the power supply requirements of the pump motor M. The Schmitt trigger 10 outputs a low-level control signal, enabling and disabling the gate drive module 6, stopping the power supply to the pump motor M, thus improving the safe operating performance of the pump motor.

[0037] In some embodiments, the frequency converter drive circuit further includes a CAN communication module 8, the transceiver terminals of which are electrically connected to the transceiver terminals of the MCU 5. By setting up the CAN communication module, communication with external systems can be achieved via the CAN communication protocol, enabling the transmission and reception of external information.

[0038] In some embodiments, the pump motor frequency converter drive circuit further includes a filter module 11. The output terminal of the rectifier transformer 1 is electrically connected to one end of the filter module 11, and the other end of the filter module 11 is grounded. The filter module 11 includes a first capacitor C1 and a second capacitor C2. The output terminal of the rectifier transformer 1 is grounded to the other ends of both the first capacitor C1 and the second capacitor C2. By providing a capacitor filter module, AC noise at the output terminal of the rectifier transformer 1 can be filtered out.

[0039] like Figure 2 As shown, the motor drive module 7 includes a first MOSFET Q1, a second MOSFET Q2, a third MOSFET Q3, a fourth MOSFET Q4, a fifth MOSFET Q5, a sixth MOSFET Q6, a first resistor R1, a second resistor R2, and a third resistor R3. The drive output terminal of the gate drive module 6 is electrically connected to the gates of the first MOSFET Q1, the second MOSFET Q2, the third MOSFET Q3, the fourth MOSFET Q4, the fifth MOSFET Q5, and the sixth MOSFET Q6, respectively.

[0040] The output terminal of the rectifier transformer 1 is electrically connected to the drain of the first MOSFET Q1, the drain of the third MOSFET Q3, and the drain of the fifth MOSFET Q5, respectively. The source of the first MOSFET Q1 is electrically connected to the drain of the fourth MOSFET Q4, and the source of the fourth MOSFET Q4 is electrically connected to one end of the first resistor R1, with the other end of the first resistor R1 grounded. The source of the sixth MOSFET Q6 is electrically connected to one end of the second resistor R2, with the other end of the second resistor R2 grounded. The source of the second MOSFET Q2 is electrically connected to one end of the third resistor R3, with the other end of the third resistor R3 grounded. The three-phase power supply terminals of the pump motor are electrically connected to the sources of the first MOSFET Q1, the third MOSFET Q3, and the fifth MOSFET Q5, respectively.

[0041] The pump motor drive process is as follows: the first MOSFET Q1 and the second MOSFET Q2 are turned on, then the second MOSFET Q2 and the third MOSFET Q3 are turned on, then the third MOSFET Q3 and the fourth MOSFET Q4 are turned on, then the fifth MOSFET Q5 and the sixth MOSFET Q6 are turned on, and finally the sixth MOSFET Q6 and the first MOSFET Q1 are turned on; the above motor drive process is repeated to drive the pump motor.

[0042] A three-phase full-bridge pump is constructed using six N-channel power MOSFETs. These six MOSFETs are divided into two groups: three high-side MOSFETs are connected to the positive terminal VBus of the power supply, and three low-side MOSFETs are connected to the negative terminal. By controlling the on / off state of the MOSFETs, the current is distributed in the pump motor windings, driving the motor to operate. By controlling the on / off state of the seventh MOSFET Q7, the drains of the first MOSFET Q1, the drains of the third MOSFET Q3, and the fifth MOSFET Q5 are controlled to switch the 48V power supply, thereby achieving the overall on / off state of the U, V, and W phases of the pump motor's power supply.

[0043] In some embodiments, the motor drive module 7 further includes a seventh MOSFET Q7. The gate of the seventh MOSFET Q7 is electrically connected to the drive output terminal of the gate drive module 6, the drain of the seventh MOSFET Q7 is electrically connected to the output terminal of the rectifier transformer 1, and the source of the seventh MOSFET Q7 is electrically connected to the drains of the first MOSFET Q1, the third MOSFET Q3, and the fifth MOSFET Q5, respectively. By configuring the seventh MOSFET Q7, the MCU5 can control the switching on and off of the seventh MOSFET Q7 to control the power supply to the motor drive module 7.

[0044] In some embodiments, an emergency stop switch S1 is also included. One end of the emergency stop switch S1 is electrically connected to the output terminal of the rectifier transformer 1, and the other end of the emergency stop switch S1 is electrically connected to the drain of the seventh MOSFET Q7. By providing the emergency stop switch S1, the power supply to the motor drive module 7 can be cut off after pressing the emergency stop switch S1 in an emergency, thereby improving the safe operating performance of the pump motor.

[0045] In some embodiments, a manual switch S2 is further included. One end of the manual switch S2 is electrically connected to the other end of the emergency stop switch S1, and the other end of the manual switch S2 is electrically connected to the drain of the seventh MOSFET Q7. By providing the manual switch S2, it can be disconnected when needed to cut off the power supply to the motor drive module.

[0046] like Figure 3 As shown, the voltage sensor 9 includes a fourth resistor R4 and a fifth resistor R5. One end of the fourth resistor R4 is electrically connected to the output terminal of the rectifier transformer 1, and the other end of the fourth resistor R4 is electrically connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is grounded, and one end of the fifth resistor R5 is electrically connected to the input terminal of the Schmitt trigger 10. The output voltage of the voltage sensor 9 is the voltage divided across the fifth resistor R5.

[0047] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A variable frequency drive circuit for a pump motor, characterized in that: It includes a rectifier transformer (1), a DC-DC conversion module (2), a power management module (3), an OR gate (4), an MCU (5), a gate drive module (6), a motor drive module (7), a voltage sensor (9), and a Schmitt trigger (10); The input terminal of the rectifier transformer (1) is connected to the mains power, and the output terminal of the rectifier transformer (1) is electrically connected to the input terminal of the DC-DC converter module (2), the input terminal of the voltage sensor (9), the power input terminal of the gate drive module (6), and the power input terminal of the motor drive module (7), respectively; the output terminal of the DC-DC converter module (2) is electrically connected to the input terminal of the power management module (3), and the voltage regulation output terminal of the power management module (3) is electrically connected to the power input terminal of the MCU (5); The grounding terminal of the voltage sensor (9) is grounded, the output terminal of the voltage sensor (9) is electrically connected to the input terminal of the Schmitt trigger (10), the output terminal of the Schmitt trigger (10) is electrically connected to one of the input terminals of the OR gate (4), the control output terminal of the MCU (5) is electrically connected to the other input terminal of the OR gate (4), the output terminal of the OR gate (4) is electrically connected to the enable control terminal of the gate drive module (6); the serial communication terminal of the MCU (5) is electrically connected to the control input terminal of the gate drive module (6), the drive output terminal of the gate drive module (6) is electrically connected to the control terminal of the motor drive module (7), and the phase drive output terminal of the motor drive module (7) is electrically connected to the power input terminal of the pump motor; wherein, the pump motor is a three-phase DC motor.

2. The pump motor frequency conversion drive circuit according to claim 1, characterized in that: It also includes a CAN communication module (8), the transceiver of which is electrically connected to the transceiver of the MCU (5).

3. The pump motor frequency conversion drive circuit according to claim 1, characterized in that: The rectifier transformer (1) is a 220V AC to 48V DC transformer, the DC conversion module (2) is a 48V to 12V power chip, the power management module (3) is a power management chip of model A4412, and the gate drive module (6) is a MOSFET driver of model AMT49101.

4. The pump motor frequency conversion drive circuit according to claim 1, characterized in that: The motor drive module (7) includes a first MOSFET (Q1), a second MOSFET (Q2), a third MOSFET (Q3), a fourth MOSFET (Q4), a fifth MOSFET (Q5), a sixth MOSFET (Q6), a first resistor (R1), a second resistor (R2), and a third resistor (R3); The drive output terminal of the gate drive module (6) is electrically connected to the gate of the first MOS transistor (Q1), the gate of the second MOS transistor (Q2), the gate of the third MOS transistor (Q3), the gate of the fourth MOS transistor (Q4), the gate of the fifth MOS transistor (Q5), and the gate of the sixth MOS transistor (Q6), respectively. The output terminal of the rectifier transformer (1) is electrically connected to the drain of the first MOSFET (Q1), the drain of the third MOSFET (Q3), and the drain of the fifth MOSFET (Q5), respectively. The source of the first MOSFET (Q1) is electrically connected to the drain of the fourth MOSFET (Q4). The source of the fourth MOSFET (Q4) is electrically connected to one end of the first resistor (R1), and the other end of the first resistor (R1) is grounded. The source of the sixth MOSFET (Q6) is electrically connected to one end of the second resistor (R2), and the other end of the second resistor (R2) is grounded. The source of the second MOSFET (Q2) is electrically connected to one end of the third resistor (R3), and the other end of the third resistor (R3) is grounded. The three-phase power supply terminals of the pump motor are electrically connected to the source of the first MOS transistor (Q1), the source of the third MOS transistor (Q3), and the source of the fifth MOS transistor (Q5), respectively.

5. The pump motor frequency conversion drive circuit according to claim 4, characterized in that: The motor drive module (7) further includes a seventh MOS transistor (Q7). The gate of the seventh MOS transistor (Q7) is electrically connected to the drive output terminal of the gate drive module (6). The drain of the seventh MOS transistor (Q7) is electrically connected to the output terminal of the rectifier transformer (1). The source of the seventh MOS transistor (Q7) is electrically connected to the drain of the first MOS transistor (Q1), the drain of the third MOS transistor (Q3), and the drain of the fifth MOS transistor (Q5), respectively.

6. The pump motor frequency conversion drive circuit according to claim 5, characterized in that: It also includes an emergency stop switch (S1), one end of which is electrically connected to the output terminal of the rectifier transformer (1), and the other end of which is electrically connected to the drain of the seventh MOS transistor (Q7).

7. The pump motor frequency conversion drive circuit according to claim 6, characterized in that: It also includes a manual switch (S2), one end of which is electrically connected to the other end of the emergency stop switch (S1), and the other end of which is electrically connected to the drain of the seventh MOSFET (Q7).

8. The pump motor frequency conversion drive circuit according to claim 1, characterized in that: The voltage sensor (9) includes a fourth resistor (R4) and a fifth resistor (R5). One end of the fourth resistor (R4) is electrically connected to the output terminal of the rectifier transformer (1), and the other end of the fourth resistor (R4) is electrically connected to one end of the fifth resistor (R5). The other end of the fifth resistor (R5) is grounded, and one end of the fifth resistor (R5) is electrically connected to the input terminal of the Schmitt trigger (10).

9. The pump motor frequency conversion drive circuit according to claim 1, characterized in that: It also includes a filter module (11), the output end of the rectifier transformer (1) is electrically connected to one end of the filter module (11), and the other end of the filter module (11) is grounded.

10. The pump motor frequency conversion drive circuit according to claim 9, characterized in that: The filter module (11) includes a first capacitor (C1) and a second capacitor (C2). The output terminal of the rectifier transformer (1) is grounded to the other end of the first capacitor (C1) and the other end of the second capacitor (C2).

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