A water pump motor constant power control method and system

Abstract

The application relates to the field of water pump motor control, in particular to a water pump motor constant power control method and system, which comprises the following steps: controlling motor rotation, keeping the motor rotation direction constant, obtaining the absolute value of the average current of the motor during operation, judging whether the absolute value of the average current is greater than a preset current value, if yes, controlling the operation current of the motor to decrease so as to reduce the power of the motor, and if no, controlling the operation current of the motor to increase so as to increase the power of the motor. The application controls the rotation direction of the water pump to be the required direction and can keep the output power of the water pump constant, thus being convenient for people to use.

Description

Technical Field

[0001] This application relates to the field of water pump motor control, and in particular to a method and system for constant power control of a water pump motor. Background Technology

[0002] In areas with higher elevations or lower water pressure, water pumps are often used to pressurize the water so that it can reach higher areas for people's convenience.

[0003] In related technologies, water pumps are used to pressurize water by controlling the rotation direction of an AC motor.

[0004] Regarding the aforementioned technologies, the inventors believe that when a water pump is pressurizing, external magnetic field interference or load can cause changes in the pump's power, resulting in unstable pressure on the water and causing inconvenience during use. Summary of the Invention

[0005] To ensure constant pump power and water pressure for ease of use, this application provides a constant power control method and system for a pump motor.

[0006] The constant power control method for a water pump motor provided in this application adopts the following technical solution:

[0007] A constant power control method for a water pump motor includes S100, controlling the motor rotation to keep the motor rotation direction constant;

[0008] S110. Obtain the absolute value of the average current of the motor during operation;

[0009] S120. Determine whether the absolute value of the average current is greater than a preset current value.

[0010] S130. If it is greater than the specified value, then control the operating current of the motor to decrease so that the power of the motor is reduced.

[0011] S140. If it is less than, then control the operating current of the motor to increase so that the power of the motor increases.

[0012] By adopting the above technical solution, the motor is controlled to start. After the AC motor starts, the direction of rotation is uncertain. The direction of rotation of the motor is controlled to be the required direction. After the motor starts normally, the absolute value of the average value of the operating current during normal operation is detected. The average current is compared with the preset value. If the average current is greater than the preset value, since the motor voltage remains unchanged, the motor current increases, which means that the motor power increases. The operating current of the motor is then reduced to decrease the motor power. If the average current is less than the preset value, it means that the current power of the motor is less than the preset value. The operating current of the motor is then increased to increase the motor power, so that the motor power remains constant, which is convenient for people to use.

[0013] Optionally, controlling the rotation of the motor includes:

[0014] S200, Obtain the starting current signal potential;

[0015] S210, Obtain the motor starting current potential;

[0016] S220. Determine whether the starting current signal voltage and the motor starting current potential are both at a low level.

[0017] S230, if so, control the thyristor to close and start the motor;

[0018] S240. If not, no action is taken.

[0019] By adopting the above technical solution, the starting current potential alternates between high and low levels. Since the motor has not yet started rotating, the motor starting current signal is at a low level. When the starting current signal becomes low, the motor starting current signal is also at a low level. At this time, the thyristor closes to control the motor to start. If the starting current signal is high and the motor starting current signal is low, the motor will not start. The potential of the starting current and the motor starting current is used to control the thyristor to control the start or stop of the motor, realizing automatic start-up without manual operation.

[0020] Optionally, keeping the motor rotation direction constant includes:

[0021] S300, Determine whether the motor's rotation direction is the desired direction;

[0022] S310. If not, it means that the current signal potential and the motor starting current signal potential are not the same. Stop the motor rotation, restart the motor and repeat step S310.

[0023] S320. If so, it means that the starting current signal potential and the motor starting current signal potential are the same, and the motor is controlled to rotate and the rotation direction is the desired direction.

[0024] By adopting the above technical solution, when the motor starts, the direction of rotation of the motor may not be the same as the required direction of rotation. Therefore, after the motor starts rotating, it is first determined whether the direction of rotation of the motor is the same as the required direction of rotation. If the direction of rotation is the same, the potential of the starting current signal and the motor starting current signal are the same. If the direction of rotation is not the same as the required direction, the starting current signal and the motor starting current signal are different. Then, the control thyristor is turned off to stop the motor from rotating. When the starting current signal becomes low, the motor is restarted and the direction of rotation of the motor is determined again. This process is repeated until the direction of rotation of the motor is the required direction of rotation, thus preventing the direction of rotation of the motor after starting from being different from the required direction.

[0025] Optionally, the absolute value of the average current of the AC current detected during motor operation includes:

[0026] S400, Obtain periodic data;

[0027] S410. Based on the periodic data, obtain the average current of the positive half-cycle current and the average current of the negative half-cycle current when the motor is running.

[0028] By adopting the above technical solution, after the motor is running normally, the periodic data of the AC current during motor operation is obtained. Then, within one cycle, the average current of the positive half-cycle current and the average current of the negative half-cycle current are obtained respectively. The change of the average current reflects the change of the power during motor operation.

[0029] Optionally, the process of controlling the motor to rotate, and making the direction of motor rotation constant, includes:

[0030] S500: Obtain the input AC voltage value;

[0031] S510: Adjust the required DC voltage output according to the input AC voltage value to power the driver chip.

[0032] By adopting the above technical solution, the chip commonly uses a 5V DC voltage, while the input voltage is an AC voltage of uncertain magnitude. First, the magnitude of the input current and voltage is obtained, then the AC voltage is converted into a DC voltage, and then the magnitude of the DC voltage is changed to the voltage used by the chip and input into the chip to power the chip. The chip can be adapted to various types of input voltages, without the need to use a special voltage to power the chip.

[0033] A constant power control system for a water pump motor includes a starting module for controlling the rotation of the motor to keep the direction of motor rotation constant.

[0034] The detection module is used to detect the absolute value of the average current of the alternating current during the operation of the motor.

[0035] The comparison module is used to determine whether the absolute value of the average current is greater than a preset current value. If it is greater, the module controls the operating current of the motor to decrease so that the power of the motor is reduced. If it is less than the preset current value, the module controls the operating current of the motor to increase so that the power of the motor is increased.

[0036] By adopting the above technical solution, the starting module controls the motor to start and rotate in the desired direction. After the motor starts, the monitoring module obtains the average current during motor operation to measure the power change. Then, the comparison module compares the average current with the preset current value. When the average current is greater than the preset current value, the motor's operating power is greater than the set value, so the input current to the motor is reduced to decrease the motor's power. When the average current is less than the preset current value, the motor's operating power is less than the set value, so the input current to the motor is reduced to increase the motor's power, keeping the motor's output power constant for convenient use.

[0037] Optionally, the startup module includes: a power conversion unit, which includes a rectifier circuit and a step-down circuit;

[0038] A rectifier circuit is used to rectify the AC voltage of the power supply into the DC voltage used by the chip.

[0039] A step-down circuit is used to adjust the DC voltage used by the chip to the required voltage and input it to the MCU chip.

[0040] Zero-crossing detection circuit unit, used to detect the potential of the starting current signal;

[0041] The Hall effect drive circuit unit is used to acquire the rotation direction when the motor starts and generate the motor starting current potential.

[0042] The thyristor drive circuit unit controls the thyristor to turn on and off to control whether the motor rotates.

[0043] By adopting the above technical solution, after the power supply is connected to the rectifier circuit unit, the AC voltage of the power supply is rectified into DC voltage. Then, the input terminal of the DC voltage is connected to the step-down circuit unit to step down the DC voltage so that the DC voltage is the voltage required for chip power supply. After the chip is powered, the zero-crossing detection circuit unit detects the potential of the starting current signal and inputs it into the chip. The Hall drive circuit unit detects the rotation direction of the motor and outputs the motor starting current signal and inputs it into the chip. When the potential of the starting current signal and the motor starting current signal are both low level, the chip controls the thyristor drive circuit unit to control the thyristor to close, thereby starting the motor.

[0044] Optionally, the detection module includes an AC current sampling circuit unit, which is used to collect the absolute value of the average current when the motor is running.

[0045] By adopting the above technical solution, after the motor is running normally, the AC current sampling circuit unit collects the average current of the motor during operation, and reflects the power change of the motor through the average current.

[0046] Optionally, the comparison module includes an MCU chip, wherein pin 5 of the MCU chip is connected to an AC current sampling circuit unit.

[0047] By adopting the above technical solution, the MCU chip's 5th pin receives the average current of the AC current sampling circuit unit and compares the average current with a preset current value. If the average current is less than the preset current value, it means that the current power of the motor is less than the preset value, so the motor's operating current is increased to increase the motor's power. If the average current is greater than the preset value, it means that the current power of the motor is greater than the preset value, so the motor's operating current is decreased to decrease the motor's power, thus keeping the motor's output power constant.

[0048] In summary, this application includes at least one of the following beneficial technical effects:

[0049] The system controls the motor's start-up. After the AC motor starts, its rotation direction is uncertain. The system controls the motor's rotation direction to the desired direction. After the motor starts normally, the system detects the absolute value of the average operating current during normal operation and compares the average current with a preset value. If the average current is greater than the preset value, since the motor voltage remains constant, the increased current indicates that the motor's power has increased. The system then reduces the operating current to lower the motor's power. If the average current is less than the preset value, it indicates that the current motor power is less than the preset value. The system then increases the operating current to increase the motor's power, thus maintaining a constant motor power for ease of use. Attached Figure Description

[0050] Figure 1 This is a schematic flowchart of a constant power control method for a water pump motor according to an embodiment of this application;

[0051] Figure 2 This is a schematic diagram of step S100 of a constant power control method for a water pump motor according to an embodiment of this application;

[0052] Figure 3 This is another flowchart of step S100 of a constant power control method for a water pump motor according to an embodiment of this application;

[0053] Figure 4 This is a schematic diagram of step S110 of a constant power control method for a water pump motor according to an embodiment of this application;

[0054] Figure 5 This is a flowchart illustrating the process before step S110 in a constant power control method for a water pump motor according to an embodiment of this application.

[0055] Figure 6 This is a system block diagram of a constant power control system for a water pump motor according to an embodiment of this application;

[0056] Figure 7 This is a circuit diagram of a constant power control system for a water pump motor according to an embodiment of this application.

[0057] Explanation of reference numerals in the attached diagram: 1. Start-up module; 2. Detection module; 3. Comparison module; 4. Power conversion unit; 5. Zero-crossing detection circuit unit; 6. Hall effect drive circuit unit. Detailed Implementation

[0058] The following is in conjunction with the appendix Figure 1-7 This application will be described in further detail.

[0059] This application discloses a constant power control method for a water pump motor, referring to... Figure 1 This includes S100, which controls the rotation of the motor to keep the direction of rotation constant.

[0060] In this embodiment, the motor is an AC motor, and its start is controlled by an MCU chip. The motor is controlled to rotate in one direction, so that after the motor rotates to pressurize the water, the water pressure only increases while the water flow direction remains unchanged.

[0061] S110: Obtain the absolute value of the average current during motor operation.

[0062] The average current is the average value of the motor's operating current over one cycle.

[0063] S120. Determine whether the absolute value of the average current is greater than the preset current value.

[0064] The preset current value within the MCU chip is the current value when the motor is running normally. The motor voltage is constant. By comparing the average current with the preset current, the actual power of the motor during operation and the preset power can be determined.

[0065] If S130 is greater than this, the operating current of the motor will be reduced, thus lowering the motor's power.

[0066] S140, if less than, then the operating current of the motor is increased to increase the power of the motor.

[0067] The implementation principle of a constant power control method for a water pump motor in this application embodiment is as follows: the MCU chip controls the motor to start and rotate the motor in the required direction. After the motor rotates, the average current during motor operation is obtained. The average current is compared with the preset current to determine whether the power of the motor is greater than the preset power. If the average current is greater than the preset current, the operating current of the motor is reduced to reduce the power of the motor. If the average current is less than the preset current, the operating current of the motor is increased to increase the power of the motor.

[0068] Reference Figure 2 Controlling the motor rotation includes:

[0069] S200, Obtain the starting current signal potential.

[0070] The starting current is supplied by an external power source to start the motor. The starting current signal potential is the potential of the external current at a certain moment. When the current is positive, it is a high potential; when the current is negative or zero, it is a low potential.

[0071] S210, Obtain the motor starting current potential.

[0072] Among them, the motor starting current potential is the potential of the current when the motor starts or runs. When the current is positive, it is a high potential, and when the current is negative, it is a low potential.

[0073] S220. Determine whether the starting current signal voltage and the motor starting current potential are both at a low level.

[0074] S230, if so, control the thyristor to close and start the motor;

[0075] S240. If not, no action is taken.

[0076] Before the motor starts, the motor is not rotating and the motor starting current is at a low potential. The starting current potential changes between a high potential and a low potential. When the starting current potential becomes a low potential, the motor starts. If the motor starting current is at a low potential while the starting current signal is at a high potential, the motor will not start. The motor will start when the starting current signal becomes a low potential.

[0077] The implementation principle of controlling motor rotation in this application embodiment is as follows: after the external power supply is connected, the starting current signal potential and the motor starting current signal potential are obtained. When both the motor starting current signal potential and the starting current signal potential are low, the motor is started. When the motor starting current signal potential and the starting current signal potential are different, the motor does not operate.

[0078] Reference Figure 3 To ensure the motor rotates in a constant direction, the following methods are included:

[0079] S300: Determine whether the motor's rotation direction is the desired direction.

[0080] The motor is an AC motor, and the direction of rotation when the motor starts is uncertain. The required direction is to pressurize the water without changing the direction of water flow.

[0081] S310. If not, it means that the current signal potential and the motor starting current signal potential are not the same. Stop the motor rotation, restart the motor and repeat step S310.

[0082] S320. If yes, it means that the starting current signal potential and the motor starting current signal potential are the same, and the motor is controlled to rotate and rotate in the desired direction.

[0083] In this process, after the motor starts, the potential of the motor starting current signal changes periodically, and the starting current signal also changes periodically. The motor only starts when both the potentials of the motor starting current signal and the starting current signal are high or low. Therefore, the frequencies of the motor starting current signal and the starting current signal are the same or multiples of each other. After the motor starts, if the motor rotates in the opposite direction to the desired direction, the motor starting current signal will be low; if the starting current signal is high, the motor will stop rotating. After the motor starts, if the potentials of the motor starting current signal and the starting current signal are not the same, the control thyristor will disconnect, causing the motor to stop rotating, and the motor starting current signal will become low. When the starting current signal becomes low, the motor restarts and continues to detect the direction of rotation. This process repeats until the direction of rotation is the desired direction. At this point, the change in the potential of the motor starting current signal and the starting current signal change synchronously, and the motor continues to run.

[0084] The implementation principle of this application embodiment to keep the motor rotation direction constant is as follows: After the motor starts, if the rotation direction is not the desired direction, the motor starting current signal is at a low level. The starting current signal changes from a low potential to a high potential. The motor starting current signal and the starting current signal potential are different, so the motor is controlled to stop rotating. The motor starting current signal becomes a low potential. When the potential of the starting current signal becomes a low potential, the motor restarts. Then the rotation direction of the motor is detected. If the rotation direction is the desired direction, the potential of the motor starting current signal and the starting current signal potential are the same and change synchronously.

[0085] Reference Figure 4 The absolute value of the average current during motor operation includes:

[0086] S400, Obtain periodic data.

[0087] The periodic data refers to the frequency of current change during motor operation, and the reciprocal of the frequency is the period.

[0088] S410. Based on the periodic data, obtain the average current of the positive half-cycle current and the average current of the negative half-cycle current when the motor is running.

[0089] The average current is the absolute value of the average current of the motor during the negative half-cycle and the average current of the motor during the positive half-cycle. The voltage of the motor remains constant, while the change in current means that the power of the motor is changing. The power of the motor in a single cycle is detected by the average current. If the average current is greater than the preset current, the operating current of the motor is reduced to reduce the power of the motor. If the average current is less than the preset current, the operating current of the motor is increased to increase the power of the motor.

[0090] The implementation principle of detecting the absolute value of the average current of the AC current during motor operation in this embodiment is as follows: obtain the frequency of the current during motor operation, obtain periodic data based on the frequency, obtain the average current of the motor during the positive half-cycle and the average current of the motor during the negative half-cycle, reflect the power change of the motor through the average current, and adjust the power of the motor. If the average current is greater than the preset current, control the motor operating current to decrease so as to reduce the power of the motor. If the average current is less than the preset current, control the motor operating current to increase so as to increase the power of the motor.

[0091] Reference Figure 5 Before controlling the motor rotation to keep the motor rotation direction constant, the following steps are included:

[0092] S500: Obtain the input AC voltage value.

[0093] The input AC voltage is an external power supply.

[0094] S510: Adjust the required DC voltage output according to the input AC voltage value to power the driver chip.

[0095] The chip is typically powered by 5V DC, while the input is AC with an unknown voltage value. The AC is rectified and then the DC voltage is adjusted to the level required to power the chip.

[0096] The implementation principle of the chip power supply in this embodiment is as follows: the magnitude of the input AC power is obtained, the AC power is rectified into DC power, the magnitude of the DC power is adjusted to the magnitude required to power the chip, and then input to the chip.

[0097] The above embodiments detail a constant power control method for a water pump motor. The following describes a constant power control system for a water pump motor applied to this constant power control method.

[0098] Reference Figure 6 and Figure 7 A constant power control system for a water pump motor, comprising:

[0099] The starting module 1 is used to control the rotation of the motor and keep the direction of motor rotation constant. The starting module 1 includes a power conversion unit 4, which includes a rectifier circuit and a step-down circuit.

[0100] The rectifier circuit is used to rectify the AC voltage of the power supply into the DC voltage used by the chip. The DC circuit unit includes a rectifier diode D1. The positive terminal of the rectifier diode D1 is connected to one end of the external power supply. In this embodiment, the external power supply can be 220V AC. The other end of the external power supply is connected in series with a rectifier diode D2, and the positive terminal of the diode D2 is connected in series. The negative terminal of the diode D2 is connected in series with the positive terminal of the voltage stabilizing capacitor C2. The other end of the voltage stabilizing capacitor C2 is connected in series with the negative terminal of the external power supply. The diode D2 is connected to pin 4 of the chip. In this embodiment, the chip model can be BP8523D.

[0101] The step-down circuit adjusts the DC voltage used by the chip to the required voltage and inputs it to the MCU chip. Pin 1 of the BP8523D chip outputs the voltage. Pin 2 is connected in series with a capacitor C3, the other end of which is connected to the output voltage. C3 is connected in parallel with a protective resistor R2, one end of which is grounded and the other end is connected to the output voltage. Pins 5 and 6 of the chip are connected in parallel and in series with an inductor L2, the other end of which is connected to the output voltage. The chip integrates a MOSFET. The chip sends a PWM pulse signal to control the MOSFET's on / off state and transmits it to the inductor L2. After the external power supply is connected to the rectifier diode, the AC power is rectified into DC power and input to the chip. The output voltage is adjusted by the PWM pulse signal emitted by the chip. Adjusting the duty cycle of the pulse signal makes the MOSFET's on / off time different. During the MOSFET's closed time, the capacitor is charged. The output voltage can be different depending on the duty cycle.

[0102] Zero-crossing detection circuit unit 5 is used to detect the potential of the starting current signal. Zero-crossing detection circuit unit 5 includes voltage divider resistors R7 and R8, which are connected in series. An external power supply is connected to R7, and the other end of R8 is connected to pin 3 of the chip. In this embodiment, the chip can be SN8F5701. One end of R8 is connected in series with the positive terminal of diode D3, and the negative terminal of diode D3 is connected to power supply 5. After the external power supply is connected, the voltage is reduced by the voltage divider resistor, and the resulting current is collected by pin 2 of the chip.

[0103] Hall effect drive circuit unit 6 is used to acquire the rotation direction when the motor starts and generate the motor starting current potential. Hall effect drive circuit unit 6 includes protective resistors R1 and R17. One end of resistor R13 is connected in series with pin 3 of chip SN8F5701, and the other end is connected to pin 1 of Hall sensor. Pin 4 of chip SN8F5701 is connected in series with R17. The other end of R17 is connected in series with pin 3 of Hall sensor. Pin 2 of Hall sensor is grounded. Capacitor C12 is connected in series with R17 and is grounded. Hall sensor is installed in motor. Hall sensor converts magnetic field signal into potential signal. When motor rotates forward, the potential signal is high potential. When motor rotates in reverse or is zero potential, the potential signal is low potential.

[0104] The thyristor drive circuit unit 7 uses the SN8F5701 chip to control the thyristor's on / off state to control whether the motor rotates. The thyristor drive circuit unit 7 includes a current-limiting resistor R9. One end of the current-limiting resistor R9 is connected to a 5V power supply, and the other end of R9 is connected in series with a voltage divider resistor R12. R12 is connected in series with a resistor R14, which is connected to pin 5 of the SN8F5701 chip. The thyristor is connected in series with the other end of R9, and the zero-crossing detection circuit unit 5 is connected in series with R12. The current emitted from pin 5 flows through the base of the thyristor, turning on the thyristor and amplifying the emitter current. An adjustable resistor is connected in series with the emitter of the thyristor and is input to the motor. The current flowing through the adjustable resistor is transmitted to the motor to control the motor to start.

[0105] Detection module 2 is used to detect the absolute value of the average AC current during motor operation. Detection module 2 includes a current sampling circuit unit 8, which collects the absolute value of the average current during motor operation. The current sampling circuit unit 8 includes a filter capacitor C6. One end of C6 is connected in series with the collector of a thyristor, and the other end is connected in series with a protection resistor R6. R6 is connected to a chip; in this embodiment, the chip can be an LM321. R6 is connected to pin 3 of the LM321 chip. A pull-up resistor R5 is connected in series between the filter capacitor C6 and the protection resistor R6. The other end of R5 is connected in series with a power supply; in this embodiment, the power supply is 5V. R5 is connected in series with a protection resistor R10, and R5 is connected in parallel with R6. A parallel resistor R10 is connected, with the other end of R10 grounded. A 5V power supply is connected in series with a pull-up resistor R3. R3 is connected in series with a protective resistor R4, which is grounded. A filter capacitor C5 is connected in parallel with R4. A filter resistor R16 is connected in series between R3 and R4. A voltage regulator capacitor C9 is connected in parallel with the filter resistor R16. A filter capacitor C11 is connected in series with the filter capacitor C9. The other end of R16 is connected in series with pin 4 of the LM321 chip. Pin 1 of the LM321 chip is input between the filter capacitors C9 and C5. The AC current of the motor flows through the filter capacitor C6 and the protective resistor R6, and then flows into pin 3 of the chip. After being processed by the LM321 chip, the negative half-cycle value of the AC current of the motor is flipped to a positive value.

[0106] Comparison module 3 is used to determine whether the absolute value of the average current is greater than a preset current value. If it is greater, the operating current of the motor is reduced to decrease the power of the motor. If it is less than the preset current, the operating current of the motor is increased to increase the power of the motor. Comparison module 3 includes an MCU chip. Pin 5 of the MCU chip is connected to the AC current sampling circuit unit 8. In this embodiment, the MCU chip model is SN8F5701. The output terminal of the current sampling circuit unit 8 is connected between resistor R9 and the collector of the thyristor. The SN8F5701 chip has a preset current for the motor to run. The preset current flows through the protection resistors R14 and R12 and into the collector of the transistor. The output current of pin 5 of the chip is adjusted by the change of the collector current, and the magnitude of the emitter current of the thyristor is controlled to control the speed of the motor in turn.

[0107] The implementation principle of a constant power control system for a water pump motor according to an embodiment of this application is as follows: After being supplied by an external power source, the AC power is rectified into DC power by a rectifier circuit. The DC power is then input to a chip BP8523D. The chip emits a pulse signal to control the MOSFET integrated within the chip. The output stage of the MOSFET is connected to a step-down circuit unit. By adjusting the duty cycle of the pulse signal emitted by the chip, the output voltage of the step-down circuit is adjusted to match the chip's voltage. The external power supply is input to a zero-crossing detection circuit. The zero-crossing detection circuit unit 5 inputs to a chip SN8F5701. The chip detects the potential of the zero-crossing detection circuit unit 5. The Hall effect drive circuit unit 6 acquires the motor's direction of rotation and outputs a potential signal. A high potential is output when the motor rotates in the desired direction, and vice versa. When the potential of the zero-crossing detection circuit unit 5 and the potential signal of the Hall drive circuit unit 6 are both low, the SN8F5701 chip starts. The chip controls the on / off state of the thyristor to control the start of the motor. When the potential changes of the zero-crossing detection circuit unit 5 and the potential signal of the Hall drive circuit unit 6 are the same, the motor runs normally. When the potential changes of the zero-crossing detection circuit unit 5 and the potential signals of the Hall drive circuit unit 6 are opposite, the motor stops rotating and restarts. After the motor is running normally, the AC current sampling circuit unit 8 detects the AC current of the motor during operation. Based on the changes in the AC current of the motor during operation, the SN8F5701 chip controls the input to the motor and adjusts the power of the motor to keep the power of the motor constant.

[0108] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method of constant power control of a water pump motor, characterized by, The method comprises the following steps: S100, controlling the rotation of the motor to keep the rotation direction of the motor constant; S110, obtaining the absolute value of the average current of the motor during operation; S120, judging whether the absolute value of the average current is greater than a preset current value; S130, if yes, reducing the operating current of the motor to reduce the power of the motor; S140, if no, increasing the operating current of the motor to increase the power of the motor; The control of the rotation of the motor comprises the following steps: S200, obtaining a starting current signal potential; S210, obtaining a motor starting current potential; S220, judging whether the starting current signal potential and the motor starting current potential are both low potentials; S230, if yes, controlling the silicon controlled rectifier to be closed to start the operation of the motor; S240, if no, no action is taken; The keeping of the rotation direction of the motor constant comprises the following steps: S300, judging whether the rotation direction of the motor is the required direction; S310, if no, it is indicated that the current signal potential and the motor starting current signal potential are different, the rotation of the motor is stopped, the motor is restarted, and the step S300 is re-executed; S320, if yes, it is indicated that the starting current signal potential and the motor starting current signal potential are the same, the rotation of the motor is controlled, and the rotation direction is the required direction; The starting current is connected by an external power supply and is used to start the motor, the starting current signal potential is the potential of the external current at a certain moment, the current is a positive value, and the current signal potential is a high potential, the current is a negative value or zero, and the current signal potential is a low potential; The motor starting current potential is the potential of the current during the starting or operation of the motor, the current is positive, and the motor starting current potential is a high potential, the current is negative, and the motor starting current potential is a low potential; Before the starting of the motor, the motor does not rotate, the motor starting current is a low potential, the starting current potential changes between a high potential and a low potential, when the starting current potential becomes a low potential, the starting current potential and the motor starting current potential are both low potentials, the motor starts, if the motor starting current is a low potential and the starting current signal is a high potential, the motor does not start, and the motor is started until the starting current signal becomes a low potential.

2. The method of claim 1, wherein: The obtaining of the absolute value of the average current of the motor during operation comprises the following steps: S400, obtaining period data; S410, obtaining the average current of the positive half cycle current and the average current of the negative half cycle current of the motor during operation according to the period data.

3. The method of claim 1, wherein: Before the control of the rotation of the motor to keep the rotation direction of the motor constant, the following steps are included: S500, obtaining an input alternating current voltage value; S510, adjusting the size of the required direct current voltage to be output according to the input alternating current voltage value to supply power to the driving chip.

4. A water pump permanent magnet motor power control system, characterized by, The method comprises the following steps: A starting module (1) is used to control the rotation of the motor to keep the rotation direction of the motor constant; A detection module (2) is used to detect the absolute value of the average current of the alternating current of the motor during operation; A comparison module (3) is used to judge whether the absolute value of the average current is greater than a preset current value, if yes, the operating current of the motor is reduced to reduce the power of the motor, and if no, the operating current of the motor is increased to increase the power of the motor.

5. The system of claim 4, wherein, The starting module (1) comprises: a power supply conversion unit (4), the power supply conversion unit (4) comprising a rectifier circuit and a step-down circuit; The rectifier circuit is used for rectifying the alternating voltage of the power supply into the direct current voltage used by the chip; The step-down circuit is used for adjusting the size of the direct current voltage used by the chip into the size of the required voltage used by the chip and inputting the MCU chip; The zero-crossing detection circuit unit (5) is used for detecting the potential of the starting current signal; The Hall drive circuit unit (6) is used for collecting the rotating direction of the motor during starting and generating the motor starting current potential; The silicon controlled drive circuit unit (7) controls the opening and closing of the silicon controlled to control whether the motor rotates.

6. The system of claim 4, wherein, The detection module (2) comprises an alternating current sampling circuit unit (8) used for collecting the absolute value of the average current when the motor operates.

7. The system of claim 4, wherein, The comparison module (3) comprises an MCU chip, and the 5 pins of the MCU chip are connected with the alternating current sampling circuit unit.

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