A constant-pressure water pump control system driven by a high-voltage brushless motor

Abstract

The present invention discloses a constant pressure water pump control system driven by a high-voltage brushless motor. The constant pressure water pump control system includes an EMI filtering module, a rectifying and filtering module, a voltage conversion module, a main processor module, a motor driving module, a fault detection and protection module, a pressure detection module, and a brushless motor interface module. The main processor module is respectively connected to the voltage conversion module, the motor driving module, the fault detection and protection module, and the pressure detection module. The present invention uses the mains power as the power supply input, and after passing through the protection, rectifying, and filtering circuits, it is converted into high-voltage direct current of about 310V and output to the brushless motor, so that the power range of the system is greatly improved. At the same time, by using a processing chip integrated with high-voltage and sensorless motor drive, and designing relevant overcurrent protection and overtemperature protection circuits, the self-protection ability of the system is greatly enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of constant pressure water pump control systems, and particularly relates to a constant pressure water pump control system driven by a high-voltage brushless motor. Background Art

[0002] With the proposal of the tasks of "carbon peak" and "carbon neutrality", the water supply system, as one of the main energy-consuming systems in cities, has gradually developed towards energy conservation and intelligence. Water pumps, as energy-consuming equipment in the water supply system, improving their operating efficiency is the key to achieving energy conservation and emission reduction in the water supply system. No matter what type of water pump, it needs to be driven by an electric motor to drive the impeller to rotate at high speed to generate power. Traditional water pumps use induction motors or brushed motors as the power source. Induction motors are large in size and difficult to adjust the operating speed, resulting in serious energy waste; brushed motors have significant disadvantages when used in harsh environments due to the limitations of the brushes. Compared with traditional power solutions, brushless motors have great advantages in many aspects. Since brushless motors do not have brushes, energy loss is reduced during operation, which means that brushless motors have less noise and less heat generation, greatly increasing the conversion efficiency of electrical energy; at the same time, brushless motors are neither restricted by the size caused by brushes nor have large-sized stators and rotors like induction motors, so the occupied space can be greatly saved; more importantly, brushless motors have a wide speed range and strong speed regulation ability, and the use of variable frequency speed regulation technology can effectively reduce the unnecessary waste of energy in the traditional water supply process, thus solving the problem of electrical energy waste in the traditional water supply mode.

[0003] At present, relatively few water pump systems in China use brushless motors as the power source, and most of the water pumps driven by brushless motors on the market are only used within a small voltage range (below 48V), and there are also some deficiencies in their functions, including low power, low intelligence level, poor self-protection ability, etc. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a constant pressure water pump control system driven by a high-voltage brushless motor, which has the advantages of a large power range, high integration, strong self-protection ability, etc.

[0005] Adopt the following technical solutions:

[0006] A constant pressure water pump control system driven by a high-voltage brushless motor includes: an EMI (electromagnetic interference) filtering module, a rectifier filtering module, a voltage conversion module, a main processor module, a motor drive module, a pressure detection module, and a brushless motor interface module.

[0007] The EMI filtering module is used to filter out electromagnetic interference at the AC input end and play a role in protecting the power supply.

[0008] The rectification and filtering module, connected to the EMI filtering module, is used to convert the AC input voltage into a DC bus voltage. The AC input voltage is the commercial power supply of 220V, and the converted DC bus voltage is 310V;

[0009] The main processor module, including the processing chip power supply module U1A, the processing chip drive pulse generation module U1B, and the processing chip status detection module U1C, is used to realize the status monitoring and overall control of the constant pressure water pump control system;

[0010] The voltage conversion module is connected to the rectification and filtering module at one end and the main processor module at the other end; after converting and outputting the DC bus voltage into direct current VCC, it supplies power to the main processor module and the pressure detection module. This voltage conversion module takes the 310V DC bus voltage as the input, and this direct current is converted from the commercial power supply through the EMI filtering module and the rectification and filtering module. In the form of external feedback resistor voltage division, it realizes DC-DC conversion and provides a relatively large current at the same time. The converted direct current VCC is 24V, which supplies power to the constant pressure water pump control system;

[0011] The motor drive module includes a three-phase field effect transistor drive circuit and a sampling resistor R32. The composition structure of each phase of the three-phase field effect transistor drive circuit is the same. One phase of the field effect transistor drive circuit includes an upper bridge arm field effect transistor Q1, a lower bridge arm field effect transistor Q2, gate resistors R20 and R21, resistors R22, R23, R24 and R25, an upper bridge arm filter capacitor C17, an inter-phase filter electrolytic capacitor C16, fast recovery diodes D3 and D4. The DC bus voltage output by the voltage conversion module is input to the drain of the upper bridge arm field effect transistor Q1, and the source of the upper bridge arm field effect transistor Q1 is connected to the drain of the lower bridge arm field effect transistor Q2. The sources of the lower bridge arm field effect transistors of the three-phase field effect transistor drive circuit are all connected to one end of the sampling resistor R32, and the other end of the sampling resistor is connected to the power ground. The sampling resistor R32 converts the current signal flowing through the motor into a voltage signal and inputs it to the COM terminal of the processing chip status detection module U1C, playing a role in overcurrent protection. One end of the gate resistor R20 is connected to the upper bridge arm field effect transistor Q1, and the other end is connected to the high-side gate drive pulse input terminal of the processing chip drive pulse generation module U1B. One end of the gate resistor R21 is connected to the lower bridge arm field effect transistor Q2, and the other end is connected to the low-side gate drive pulse input terminal of the processing chip drive pulse generation module U1B. The cathode of the fast recovery diode D3 is connected to the high-side gate drive pulse input terminal of the processing chip drive pulse generation module U1B, the anode of the fast recovery diode D3 is connected to one end of the resistor R22, the other end of the resistor R22 is connected to the gate resistor R20, the cathode of the fast recovery diode D4 is connected to the low-side gate drive pulse input terminal of the processing chip drive pulse generation module U1B, the anode of the fast recovery diode D4 is connected to one end of the resistor R23, and the other end of the resistor R23 is connected to the gate resistor R21. The upper bridge arm filter capacitor C17 is an electrolytic capacitor, the positive electrode is connected to the drain of the upper bridge arm field effect transistor Q1, and the negative electrode is connected to the power ground, used to filter the ripple of the voltage input at the drain end of the upper bridge arm field effect transistor Q1. The positive electrode of the inter-phase filter electrolytic capacitor C16 is connected to the drain of the upper bridge arm field effect transistor Q1, and the negative electrode is connected to the source of the lower bridge arm field effect transistor Q2, used to filter the voltage ripple at the intersection of the three lower bridge arms. The resistor R24 is connected between the gate and the source of the upper bridge arm field effect transistor Q1. The resistor R25 is connected between the gate and the source of the lower bridge arm field effect transistor Q2. The three-phase connection lines of the motor are led out between the source of the upper bridge arm field effect transistor and the drain of the lower bridge arm field effect transistor in the three-phase field effect transistor drive circuit. This module is used to realize the starting, commutation and speed regulation of the brushless motor;

[0012] The pressure detection module is connected to the main processor module and is used to realize the analog-to-digital conversion and impedance matching of the pressure signal;

[0013] The brushless motor interface module is connected to the motor drive module.

[0014] Further, the EMI filtering module includes Y capacitor groups C22, C23 and C29, C30, fuse F1, thermistor TH2, varistors RV1 and RV2, X capacitor C25, common mode inductor L2, current limiting resistor R39, and capacitor C31; the fuse F1 is connected to the mains live wire, the thermistor TH2 is connected to the mains neutral wire, the varistor RV1 is connected between the mains input live wire and the mains neutral wire, the varistor RV2 is connected between the two ends of the AC output, the C22 is connected between the mains live wire and the ground wire, the C23 is connected between the neutral wire and the ground wire, the C29 is connected between one end of the AC output and the ground wire, the C30 is connected between the other end of the AC output and the ground wire, the fourth end and the first end of the common mode inductor L2 are respectively connected to both ends of the C25, the third end and the second end are respectively connected to both ends of the current limiting resistor R39, the C31 is connected in parallel with the varistor RV2, and the positive and negative ends of the AC output are led out from both ends of the capacitor C31.

[0015] Further, the rectification and filtering module includes a rectifier bridge D9, an inductor L1, electrolytic capacitors C24 and C27, and capacitors C26 and C28. The B terminal and the C terminal of the rectifier bridge D9 are respectively connected to the positive and negative ends of the AC output of the EMI filtering module. The A terminal of the rectifier bridge D9 is connected to one end of the inductor L1, and the D terminal is connected to the power ground. The other end of the inductor L1 is connected to the positive electrodes of the electrolytic capacitors C24 and C27; the negative electrodes of the electrolytic capacitors C24 and C27 are connected to the power ground; the capacitors C26 and C28 are respectively connected in parallel after the electrolytic capacitors C24 and C27, and VM is led out from the positive electrode of the electrolytic capacitor C27 as the output DC bus voltage output.

[0016] Further, the voltage conversion module includes a voltage conversion chip U3, a bypass capacitor C32, feedback resistors R40 and R41, capacitors C33, C34 and C36, diodes D10 and D11, an inductor L3, and an electrolytic capacitor C35. One end of the capacitor C32 is connected between the bypass terminal and the source terminal of the voltage conversion chip U3. The feedback resistor R40 is connected between the feedback terminal and the source terminal of the voltage conversion chip U3. One end of the feedback resistor R41 is connected to the feedback terminal of the voltage conversion chip U3, and the other end is connected to the DC voltage output terminal VCC through the diode D11. The capacitor C33 is in parallel with the feedback resistor R41, the capacitor C34 is in parallel with the feedback resistor R40, and the capacitor C36 is connected between the DC voltage output terminal VCC and the logic ground. The cathode of the diode D10 is connected to the source terminal of the voltage conversion chip U3, and the anode is connected to the logic ground. One end of the inductor L3 is connected to the source terminal of the voltage conversion chip, and the other end is connected to the anode of the diode D11. The DC bus voltage is output to the positive electrode of the electrolytic capacitor C36, and the negative electrode is connected to the logic ground.

[0017] Further, the power supply module U1A of the processing chip includes capacitors C3, C5 and C7. The positive power input terminal of the power supply module of the processing chip is connected to the DC voltage output terminal VCC, the negative power input terminal is connected to the logic ground, and the power output terminal outputs a DC voltage VDD. One end of the capacitor C3 is connected to the logic ground, and the other end is connected to the first reference terminal of the processing chip drive pulse generation module U1B. The capacitor C5 is connected between the logic ground and the DC voltage input terminal VCC, and the capacitor C7 is connected between the logic ground and the power output terminal of the processing chip drive pulse generation module U1B. The processing chip drive pulse generation module U1B includes capacitors C1, C2, C8, C9 and C10. The capacitor C1 is connected between the logic ground and the second reference terminal of the processing chip drive pulse generation module U1B, the capacitor C2 is connected between the logic ground and the third reference terminal of the processing chip drive pulse generation module U1B, and the capacitors C8, C9 and C10 are respectively connected between the gate drive power terminal and the gate drive reset terminal of each phase. The processing chip status detection module U1C includes a DC bus overvoltage detection circuit, a brushless motor overcurrent circuit, and a processing chip overtemperature detection circuit. The DC bus overvoltage detection circuit inputs the sampled voltage to the voltage detection terminal of the processing chip. The brushless motor overcurrent detection circuit inputs the converted voltage value to the overcurrent detection terminal of the processing chip through the sampling resistor R32. The processing chip overtemperature detection circuit divides the voltage by the thermistor and an ordinary resistor, and then converts the temperature value into a voltage signal and inputs it to the overtemperature detection terminal.

[0018] Further, the values of the gate resistors R20 and R21 are 10 - 150 Ω. The appropriate gate resistor value must be obtained through experiments so that the field effect transistor has a relatively fast on-off speed and a small overshoot of the surge voltage.

[0019] Further, the pressure detection module is connected to the pressure sensor at the water outlet. The pressure sensor outputs a 4 - 20 mA current, and the current signal is converted into a voltage signal not exceeding 5V through the pressure detection circuit as an analog input. The main processor module controls the motor speed by processing this value.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. By adopting a brushless motor powered by a large voltage, while saving energy and reducing consumption, the power of the water pump system is increased, enabling the water pump to operate within a large power range, avoiding situations such as poor water outlet effect and mismatch between water outlet capacity and pressure due to insufficient power, and ensuring the stability of the water pump's water outlet.

[0022] 2. A highly integrated processing chip is adopted, and the motor commutation adopts a sensorless (without position sensor) control scheme, greatly reducing the volume of the overall control system. The main processing chip can not only act as a gate driver but also be connected to peripherals as an ordinary MCU (microprocessor) for data processing. At the same time, the main processor can be compatible with both sensor and sensorless control schemes. By adopting the sensorless control technology, the overall volume of the water pump system is effectively controlled.

[0023] 3. The adopted main processor has a dedicated over - temperature, over - current, and over - voltage fault detection circuit. The sampled signals can be effectively analyzed and processed inside the main processor, ensuring the reliability of the water pump system. At the same time, the operating conditions of the water pump system can be real - time feedback through external devices, with strong interactivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0025] Figure 1 is the structural block diagram of the embodiment of the present invention.

[0026] Figure 2 is the circuit diagram of the EMI filtering module.

[0027] Figure 3 is the circuit diagram of the rectification and filtering module.

[0028] Figure 4 is the circuit diagram of the voltage conversion module.

[0029] Figure 5It is the circuit diagram of the motor drive module.

[0030] Figure 6 It is the circuit diagram of the main controller module.

[0031] Figure 7 It is the circuit diagram of the pressure detection module.

[0032] Figure 8 It is the circuit diagram of the brushless motor interface module.

[0033] Specific implementation manners

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0035] As Figure 1 shown, the present invention includes an EMI (electromagnetic interference) filtering module a, a rectifying and filtering module b, a voltage conversion module c, a main processor module d, a motor drive module e, a pressure detection module f, and a brushless motor interface module g.

[0036] EMI filtering module a: includes an AC mains input 1, an overcurrent and overvoltage protection circuit 2, and an EMI filtering circuit 3.

[0037] Rectifying and filtering circuit b: includes a rectifier bridge module 4 and an LC filtering circuit 5. The rectifier bridge is a bridge rectifier module composed of four diodes, and its model is GBU8A.

[0038] Voltage conversion module c: includes a voltage conversion chip 6 and an output terminal auxiliary circuit 7. The voltage conversion chip model is LNK3204D.

[0039] Main processor module d: includes a processing chip 8, a DC bus overvoltage detection circuit 9, a processing chip overtemperature detection circuit 10, and a brushless motor overcurrent detection circuit 11. The processing chip 8 is a dedicated brushless motor control chip, and its model is IMD111T-6F040.

[0040] Motor drive module e: includes a gate drive circuit 12, a three-phase inverter bridge circuit 13, a capacitor filtering circuit 14, and a current sampling resistor 15. The three-phase inverter bridge circuit 13 is composed of 6 field effect transistors, and its model is IPB65R660CFD.

[0041] Pressure detection module f: includes a pressure sensor interface and its detection circuit 16.

[0042] Brushless motor interface module g: includes the interface circuit 17 of a brushless motor without a position sensor.

[0043] As Figure 2 shown, this figure is the EMI filter circuit diagram. It includes the mains AC input, Y capacitor bank (C22 and C23, C29 and C30), fuse (F1), thermistor (TH2), varistors (RV1, RV2), X capacitor (C25), common mode inductor (L2), current limiting resistor (R39), and capacitor (C31). The fuse F1 is connected to the mains live wire; the thermistor TH2 is connected to the mains neutral wire; the varistor RV1 is connected between the mains live wire and neutral wire inputs, and the varistor RV2 is connected between the two ends of the AC output; the Y capacitor bank (C22 and C23) is respectively connected between the mains live wire and the ground wire, and the neutral wire and the ground wire, and the Y capacitor bank (C29 and C30) is connected between one end of the AC output and the ground wire, and the other end of the AC output and the ground wire; the fourth end and the first end of the common mode inductor L2 are connected to both ends of the X capacitor C25, and the third end and the second end are connected to the current limiting resistor R39; the capacitor C31 is connected in parallel with the varistor RV2, and the positive and negative ends of the AC output are led out from both ends of the capacitor.

[0044] As Figure 3 shown, this figure is the rectifier and filter circuit diagram. It includes a rectifier bridge (D9), inductor (L1), electrolytic capacitors (C24, C27), and capacitors (C26, C28). The B terminal and the C terminal of the rectifier bridge D9 are respectively connected to Figure 1 the positive and negative ends of the AC output shown, the A terminal of the rectifier bridge D9 is connected to one end of the inductor L1, and the D terminal is connected to the power ground; one end of the inductor L1 is connected to the A terminal of the rectifier bridge D9, and the other end is connected to the positive electrode of the electrolytic capacitor C24; the positive electrodes of the electrolytic capacitors C24 and C27 are connected to one end of the inductor L1, and the negative electrodes are connected to the power ground; the capacitors C26 and C28 are respectively connected in parallel after the electrolytic capacitors C24 and C27, and VM is led out from the positive electrode of the electrolytic capacitor C27 as the DC bus voltage output.

[0045] As Figure 4As shown in the figure, this is the circuit diagram of the voltage conversion module, which includes a voltage conversion chip (U3), bypass capacitors (C32), feedback resistors (R40, R41), capacitors (C33, C34, C36), diodes (D10, D11), an inductor (L3), and an electrolytic capacitor (C35). It is characterized in that one end of the capacitor C32 is connected between the bypass terminal and the source terminal of the voltage conversion chip; one end of the feedback resistor R40 is connected between the feedback terminal and the source terminal of the voltage conversion chip, and one end of the feedback resistor R41 is connected to the feedback terminal of the voltage conversion chip, and the other end passes through the diode D11 to the DC voltage output terminal VCC; the capacitor C33 is connected in parallel with the feedback resistor R42, the capacitor C34 is connected in parallel with the feedback resistor R41, and the capacitor C36 is connected between the DC voltage output terminal VCC and the logic ground; the cathode of the diode D10 is connected to the source terminal of the voltage conversion chip, and the anode is connected to the logic ground. One end of the inductor L3 is connected to the source terminal of the voltage conversion chip, and the other end is connected to the anode of the diode D11; the positive electrode of the electrolytic capacitor C36 is connected to the DC voltage output terminal VCC, and the negative electrode is connected to the logic ground.

[0046] Compared with common voltage conversion circuits, the entire voltage conversion module achieves higher voltage conversion efficiency with fewer components and lower cost. The voltage conversion chip converts the high voltage VM into the low voltage VCC by controlling the on and off of the internal field effect transistor. The capacitor C32 provides the functions of sampling and holding. The resistors R40 and R41 are used to achieve different output voltages. The resistor R40 determines the change rate of the output voltage, and the resistor R41 provides a DC bias for the output voltage. The calculation formula of its output voltage is shown in Equation 1 below.

[0047]

[0048] Among them, V FB is the reference voltage output inside the chip, which is fixed at 2V, and I FB is the feedback current output inside the chip, which is fixed at 49 μA, and V CC is the output DC voltage value.

[0049] Since the brushless motor requires a certain time to start, a capacitor C33 is connected in parallel with the resistor R41 to achieve the soft start function. The inductor L3 is used to prevent sudden changes in current and continues to flow through the L3, C35, D10 loop. At the same time, L3, C35, and C36 are used to filter out the ripples on the output DC voltage.

[0050] As Figure 5 shown in the figure, this is the schematic diagram of the main controller circuit. The processing chip 8 is divided into three modules. Figure (a) is the power supply module of the processing chip, Figure (b) is the driving pulse generation module of the processing chip, and Figure (c) is the state detection module of the processing chip.

[0051] AsFigure 5 (As shown in (a), the power supply module of the processing chip includes the power supply part U1A of the processing chip and capacitors (C3, C5, C7). It is characterized in that the positive power input terminal of the processing chip is connected to Figure 4 the DC voltage output terminal VCC shown, the negative power input terminal of the processing chip is connected to the logic ground, and the power output terminal of the processing chip outputs the DC voltage VDD; one end of the capacitor C3 is connected to the logic ground, and the other end is connected to the first reference terminal of the processing chip U1B; the capacitor C5 is connected between the logic ground and the DC voltage input terminal VCC, and the capacitor C7 is connected between the logic ground and the power output terminal of the processing chip.)

[0052] As Figure 5 (As shown in (b), the driving pulse generation module U1B of the processing chip includes the driving pulse generation part U1B of the processing chip and capacitors (C1, C2, C8, C9, C10). It is characterized in that the capacitor C1 is connected between the logic ground and the second reference terminal of the processing chip U1B, and the capacitor C2 is connected between the logic ground and the third reference terminal of the processing chip U1B; the driving pulse generation module is used to generate a PWM wave to drive the three-phase field effect transistor, and the high-side gate driving pulse input terminal of each phase is input to the gate of the upper-bridge arm field effect transistor through the upper-bridge arm gate resistor; the gate driving power supply terminal of each phase is respectively connected to the gate driving reset terminal of each phase through capacitors (C8, C9, C10), and a signal is led out from the reset terminal and input to the intersection of the upper and lower bridge arm field effect transistors of the gate driving circuit.)

[0053] As Figure 5 (As shown in (c), the processing chip status detection module includes the processing chip over-temperature detection circuit ①, the DC bus over-voltage detection circuit ②, and the brushless motor over-current detection circuit ③. It is characterized in that the processing chip over-temperature detection circuit converts the temperature value into a voltage signal and inputs it to the over-temperature detection terminal after dividing the voltage by the thermistor and the ordinary resistor, and the DC bus over-voltage detection circuit inputs the sampled voltage to the voltage detection terminal of the processing chip; the brushless motor over-current detection circuit inputs the converted voltage value to the over-current detection terminal of the processing chip after being processed by the voltage dividing circuit by the sampling resistor R32;)

[0054] The over-temperature detection circuit ① of the processing chip includes a light-emitting diode D1, a resistor R3, a thermistor TH1, and a capacitor C11. One end of the resistor R3 is connected to the DC voltage VDD, and the other end is connected to the thermistor TH1. The junction of the two is led out to the over-temperature monitoring terminal of the processing chip. The other end of the thermistor is connected to the logic ground; the light-emitting diode D1 is connected in parallel with the thermistor TH1, and the cathode is connected to the logic ground; the capacitor C11 is connected in parallel with the thermistor TH1. Since the increase in temperature will cause the resistance value of the thermistor to decrease, resulting in a decrease in the voltage input to the over-temperature detection terminal. When it is lower than the set threshold value, the processing chip performs over-temperature protection; the light-emitting diode D1 is used to indicate the working state of the chip at this time, and it changes from bright to dark as the temperature of the processing chip increases. This is the over-temperature detection circuit 10 of the processing chip;

[0055] The over-voltage detection circuit ② of the processing chip DC bus includes resistors R10, R11, R12, and a capacitor C12. One end of the resistor R10 is connected to the DC bus voltage VM, and the other end is connected to R11. The junction of the two is led out to the over-voltage detection terminal of the processing chip. The other end of the resistor R11 is connected to the logic ground; the capacitor C12 is connected in parallel with the resistor R11; the resistor R12 is a 0Ω resistor, one end of which is connected to the logic ground and the other end is connected to the power ground. By selecting appropriate resistance values of R10 and R11, the voltage detection terminal can accurately collect the voltage value of the DC bus. When the DC bus voltage value is too large, the processing chip can achieve self-protection. This is the over-voltage detection circuit 9;

[0056] As Figure 6 shown, this figure is the circuit diagram of the motor drive module. Six N-channel field effect transistors form a three-phase inverter bridge circuit 10. The field effect transistors on the upper and lower same bridge arms form one phase. The six field effect transistors are combined in pairs to form the U, V, and W phases of the brushless motor and conduct in the order of Q1Q4 - Q1Q6 - Q3Q6 - Q3Q2 - Q5Q2 - Q5Q4 to complete six-step commutation and realize the rotation of the motor. The gate drive circuit and the capacitor filter circuit on each phase are the same. The following takes the U phase as an example for illustration:

[0057] The U phase includes the upper-bridge MOSFET (Q1), the three-phase lower-bridge MOSFET (Q2), resistors (R20, R21, R22, R23, R24, R25), the upper-bridge filtering capacitor (C17), the inter-phase filtering electrolytic capacitor (C16), and diodes (D3, D4). It is characterized in that the DC bus voltage is input to the drain of the upper-bridge MOSFET, the source is connected to the drain of the lower-bridge MOSFET, and the source of the lower-bridge MOSFET is connected to the power ground through the sampling resistor R32; one ends of the gate resistors R20 and R21 are respectively connected to the gates of the upper and lower-bridge MOSFETs, and the other ends are respectively connected to the high-side and low-side gate drive pulse output terminals of the pulse generation module U1B; the cathodes of the diodes D3 and D4 are respectively connected to the high-side and low-side gate drive pulse output terminals of the pulse generation module U1B, and the anodes are respectively connected to one ends of the resistors R22 and R23; one ends of the resistors R22 and R23 are connected to the anodes of the diodes D3 and D4, and the other ends are respectively connected to the gates of the upper and lower-bridge MOSFETs; the positive electrode of the upper-bridge filtering capacitor is connected to the drain of the upper-bridge MOSFET, and the negative electrode is connected to the power ground; the positive electrode of the inter-phase filtering capacitor C16 is connected to the drain of the upper-bridge MOSFET, and the negative electrode is connected to the source of the lower-bridge MOSFET.

[0058] The sources of the three-phase lower-bridge MOSFETs converge to one end of the sampling resistor R32 and are connected to the current detection port of the processing chip status detection module C, and the other end of the sampling resistor is connected to the power ground. The sampling resistor R32 converts the current signal flowing through the motor into a voltage signal, and the voltage signal is input to Figure 5 the current detection port of the processing chip status detection module shown; as Figure 5 shown in the overcurrent detection circuit ③, it includes the signal source of the COM terminal, resistors R17, R18, and R19, and capacitor C14. The signal of the COM terminal is introduced from the upper end of the sampling resistor R32. The signal of the COM terminal is divided by the resistors R17, R18, and R19 and input to the overcurrent detection terminal of the processing chip. One ends of the resistors R17, R18, and R19 are connected together. The other end of the resistor R17 is connected to the overcurrent detection terminal of the processing chip. The other end of the resistor R18 is connected to Figure 5 (a) the VDD shown, and the other end of the resistor R19 is connected to the sampling port of the processing chip. Its overcurrent detection principle is shown in Equation 2;

[0059]

[0060] Among them, V iss is the voltage obtained at the overcurrent detection terminal of the processing chip, I shunt is the sampled current, and V DD is the +5V input voltage. V iss can receive a maximum voltage of 5V. By matching the values of R17 and R18, the sampled current I shunt is converted into a voltage signal. When Viss When the obtained value is greater than 5V, overcurrent protection is completed inside the processing chip.

[0061] The entire motor drive circuit is powered by a high-voltage input. Since the brushless motor is an inductive component, when the current change rate is too fast, a large surge voltage will be generated. Therefore, some measures need to be taken to prevent the field-effect transistor from being broken down. The electrolytic capacitor C17 is used to filter the ripple of the input voltage at the drain terminal of the field-effect transistor Q1; the value of the gate resistor R20 will affect the switching time, switching loss, and surge voltage of the field-effect transistor. It is necessary to select an appropriate resistance value to make the field-effect transistor have good dynamic characteristics; to ensure that the parasitic capacitance between the gate and source of the field-effect transistor discharges quickly when it is turned off, fast-recovery diodes and current-limiting resistors (R22 and D3, R23 and D4) are anti-parallel connected on the gate resistor of the field-effect transistor. Among them, the fast-recovery diode can shorten the turn-off time of the MOSFET and reduce the turn-off loss, and the current-limiting resistor prevents the main processor current from being too large and burning out when it is turned off;; the resistor R24 plays a role in discharging static electricity. A small amount of static electricity can generate a very high voltage between the gate terminal and the source terminal of the field-effect transistor. If it is not discharged in time, it may break down the field-effect transistor. Therefore, the resistor R24 is needed to protect the field-effect transistor; the electrolytic capacitor C16 is used to filter the voltage ripple at the intersection of the three lower bridge arms to prevent its voltage from being too low and causing damage to the processing chip.

[0062] As Figure 7 shown, this figure is the circuit diagram of the pressure detection module. It includes an operational amplifier (U2), resistors (R4, R8), an electrolytic capacitor (C13), and a capacitor (C15). It is characterized in that the positive power input terminal of the operational amplifier (U2) is connected to the DC voltage output terminal VCC, the negative power input terminal is connected to the logic ground, its non-inverting input terminal is connected to its output terminal, its output terminal is connected to the voltage detection terminal of the processing chip detection module U1C, and its inverting input terminal is connected to the external pressure input terminal through the resistor R8; the resistor R4 is connected between the external pressure input and the logic ground; the positive electrode of the electrolytic capacitor C13 is connected to the output terminal of the operational amplifier, and the other end is connected to the logic ground; the capacitor C15 is connected in parallel with the capacitor C13.

[0063] The external pressure sensor inputs a current of 4-20mA through the J2 port to represent the magnitude of the pressure value. The current signal is converted into a voltage signal of 1-5V through the resistor R4, and then the impedance matching is completed through the voltage follower composed of the resistor R8 and the operational amplifier LM321. Finally, after passing through the electrolytic capacitor C13 and the capacitor C15, filtering is completed and input to Figure 6 (c) the pressure acquisition terminal of the processing chip. The pressure acquisition terminal of the processing chip can acquire the analog signal and make corresponding conversions to adjust the speed of the brushless motor to achieve pressure matching, and thus the constant pressure at the water outlet end of the water pump can be realized.

[0064] As Figure 8As shown, the figure is a three-phase interface circuit of a brushless motor. Three copper wires are respectively led out from the three phases of the brushless motor into the interface circuit, and each phase wire is connected between the upper and lower bridge arms of the corresponding phase shown, completing the electrical connection. Figure 5 between the upper and lower bridge arms of the corresponding phase shown, completing the electrical connection.

[0065] Working principle:

[0066] The constant pressure water supply control system mainly consists of a water supply pipeline, a pump group, a motor, a pressure stabilizing tank, and valves, etc. The constant pressure water pump control system, as a subsystem of the constant pressure water supply control system and also as its power source, can change the flow rate of the system by adjusting the speed of the brushless motor of the water pump to achieve a constant outlet pressure. The system uses the commercial power supply as the power input. After EMI filtering and rectifier filtering, 310V DC is obtained and output to the motor drive module. At high voltage, the power of the system is effectively improved; at the same time, 310V DC is converted into 24V DC through the voltage conversion module for power supply to the processing chip. The voltage conversion chip in the module can keep a large current at the output end to ensure the stable operation of the system.

[0067] When the constant pressure water pump control system is working, the pressure sensor inputs the pressure value measured at the outlet into the pressure receiving port of the control system in the form of a 4 - 20mA current signal. The control system converts the current signal into a voltage signal through a sampling resistor and performs impedance matching and filtering, and finally inputs it to the pressure acquisition end of the processing chip. After the processing chip obtains the voltage value representing the pressure, it calculates the corresponding pressure value through conversion, and adjusts the PWM signal output to the gate of the field effect transistor in the motor drive circuit according to the pressure error, thereby adjusting the on - off of the field effect transistor and controlling the voltage output to the brushless motor, so as to control the speed of the motor. When the brushless motor is running, the sampling resistor will detect the current flowing through the motor. If the current value obtained by the processing chip exceeds the rated current value, it will make a protection reaction to avoid causing harm; the thermistor will detect the temperature of the processing chip. If the temperature of the processing chip is too high, it will give a warning and perform self - protection to prevent damage to the water pump control system.

[0068] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above - mentioned exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non - restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0069] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A constant pressure water pump control system driven by a high voltage brushless motor, characterized in that, Including: An EMI filtering module for filtering electromagnetic interference at the AC input end and protecting the power supply; A rectifying and filtering module connected to the EMI filtering module for converting the AC input voltage into a DC bus voltage; A main processor module including a processing chip power supply module U1A, a processing chip drive pulse generation module U1B, and a processing chip status detection module U1C; A voltage conversion module, with one end connected to the rectifying and filtering module and the other end connected to the main processor module; after converting and outputting the DC bus voltage into a direct current VCC, it supplies power to the main processor module and the pressure detection module; The motor drive module includes a three-phase field-effect transistor drive circuit and a sampling resistor R32. The constituent structure of each phase of the three-phase field-effect transistor drive circuit is the same. One phase of the field-effect transistor drive circuit includes an upper-bridge-arm field-effect transistor Q1, a lower-bridge-arm field-effect transistor Q2, gate resistors R20 and R21, resistors R22, R23, R24, and R25, an upper-bridge-arm filter capacitor C17, an inter-phase filter electrolytic capacitor C16, fast-recovery diodes D3 and D4. The DC bus voltage output by the voltage conversion module is input to the drain of the upper-bridge-arm field-effect transistor Q1, and the source of the upper-bridge-arm field-effect transistor Q1 is connected to the drain of the lower-bridge-arm field-effect transistor Q2. The sources of the lower-bridge-arm field-effect transistors of the three-phase field-effect transistor drive circuit are all connected to one end of the sampling resistor R32, and the other end of the sampling resistor R32 is connected to the power ground. The sampling resistor R32 converts the current signal flowing through the motor into a voltage signal and inputs it to the COM terminal of the processing chip status detection module U1C, playing a role in overcurrent protection. One end of the gate resistor R20 is connected to the gate of the upper-bridge-arm field-effect transistor Q1, and the other end is connected to the high-side gate drive pulse input terminal of the processing chip drive pulse generation module U1B. One end of the gate resistor R21 is connected to the gate of the lower-bridge-arm field-effect transistor Q2, and the other end is connected to the low-side gate drive pulse input terminal of the processing chip drive pulse generation module U1B. The cathode of the fast-recovery diode D3 is connected to the high-side gate drive pulse input terminal of the processing chip drive pulse generation module U1B, the anode of the fast-recovery diode D3 is connected to one end of the resistor R22, and the other end of the resistor R22 is connected to one end of the gate resistor R20. The cathode of the fast-recovery diode D4 is connected to the low-side gate drive pulse input terminal of the processing chip drive pulse generation module U1B, the anode of the fast-recovery diode D4 is connected to one end of the resistor R23, and the other end of the resistor R23 is connected to one end of the gate resistor R21. The upper-bridge-arm filter capacitor C17 is an electrolytic capacitor, with the positive electrode connected to the drain of the upper-bridge-arm field-effect transistor Q1 and the negative electrode connected to the power ground, for filtering the ripple of the voltage input at the drain end of the upper-bridge-arm field-effect transistor Q1. The positive electrode of the inter-phase filter electrolytic capacitor C16 is connected to the drain of the upper-bridge-arm field-effect transistor Q1, and the negative electrode is connected to the source of the lower-bridge-arm field-effect transistor Q2, for filtering the voltage ripple at the junction of the three lower bridge arms. The resistor R24 is connected between the gate and the source of the upper-bridge-arm field-effect transistor Q1. The resistor R25 is connected between the gate and the source of the lower-bridge-arm field-effect transistor Q2. The three-phase connection lines of the motor are led out between the source of the upper-bridge-arm field-effect transistor and the drain of the lower-bridge-arm field-effect transistor in the three-phase field-effect transistor drive circuit; The pressure detection module is connected to the main processor module; The brushless motor interface module is connected to the motor drive module.

2. The constant pressure water pump control system driven by a high voltage brushless motor according to claim 1, characterized in that, The EMI filtering module includes Y - capacitor groups C22, C23 and C29, C30, fuse F1, thermistor TH2, varistors RV1 and RV2, X - capacitor C25, common - mode inductor L2, current - limiting resistor R39, and capacitor C31. The fuse F1 is connected to the mains live wire, the thermistor TH2 is connected to the mains neutral wire, the varistor RV1 is connected between the mains input live wire and the mains neutral wire, the varistor RV2 is connected between the two ends of the AC output. The C22 is connected between the mains live wire and the ground wire, the C23 is connected between the mains neutral wire and the ground wire, the C29 is connected between one end of the AC output and the ground wire, the C30 is connected between the other end of the AC output and the ground wire. The fourth end and the first end of the common - mode inductor L2 are respectively connected to both ends of the C25, and the third end and the second end are respectively connected to both ends of the current - limiting resistor R39. The C31 is connected in parallel with the varistor RV2, and the positive and negative AC output terminals are led out from both ends of the capacitor C31.

3. The constant pressure water pump control system driven by a high voltage brushless motor according to claim 1, characterized in that, The rectification and filtering module includes a rectifier bridge D9, inductor L1, electrolytic capacitors C24 and C27, and capacitors C26 and C28. The B terminal and the C terminal of the rectifier bridge D9 are respectively connected to the positive and negative ends of the AC output of the EMI filtering module. The A terminal of the rectifier bridge D9 is connected to one end of the inductor L1, and the D terminal is connected to the power ground. The other end of the inductor L1 is connected to the positive electrodes of the electrolytic capacitors C24 and C27. The negative electrodes of the electrolytic capacitors C24 and C27 are connected to the power ground. The capacitors C26 and C28 are respectively connected in parallel after the electrolytic capacitors C24 and C27, and VM is led out from the positive electrode of the electrolytic capacitor C27 as the output DC bus voltage.

4. The constant pressure water pump control system driven by a high voltage brushless motor according to claim 1, characterized in that, The voltage conversion module includes a voltage conversion chip U3, bypass capacitor C32, feedback resistors R40 and R41, capacitors C33, C34 and C36, diodes D10 and D11, inductor L3, and electrolytic capacitor C35. One end of the capacitor C32 is connected between the bypass terminal and the source terminal of the voltage conversion chip U3. The feedback resistor R40 is connected between the feedback terminal and the source terminal of the voltage conversion chip U3. One end of the feedback resistor R41 is connected to the feedback terminal of the voltage conversion chip U3, and the other end passes through the diode D11 to the DC voltage output terminal VCC. The capacitor C33 is connected in parallel with the feedback resistor R41, the capacitor C34 is connected in parallel with the feedback resistor R40, the capacitor C36 is connected between the DC voltage output terminal VCC and the logic ground. The cathode of the diode D10 is connected to the source terminal of the voltage conversion chip U3, and the anode is connected to the logic ground. One end of the inductor L3 is connected to the source terminal of the voltage conversion chip, and the other end is connected to the anode of the diode D11. The DC bus voltage is output to the positive electrode of the electrolytic capacitor C36, and the negative electrode is connected to the logic ground.

5. The constant pressure water pump control system driven by a high voltage brushless motor according to claim 4, characterized in that, The power supply module U1A of the processing chip includes capacitors C3, C5, and C7. The positive power input terminal of the power supply module of the processing chip is connected to the DC voltage output terminal VCC, the negative power input terminal is connected to the logic ground, and the power output terminal outputs a DC voltage VDD. One end of the capacitor C3 is connected to the logic ground, and the other end is connected to the first reference terminal of the driving pulse generation module U1B of the processing chip; the capacitor C5 is connected between the logic ground and the DC voltage input terminal VCC, and the capacitor C7 is connected between the logic ground and the power output terminal of the driving pulse generation module U1B of the processing chip; the driving pulse generation module U1B of the processing chip includes capacitors C1, C2, C8, C9, and C10. The capacitor C1 is connected between the logic ground and the second reference terminal of the driving pulse generation module U1B of the processing chip, the capacitor C2 is connected between the logic ground and the third reference terminal of the driving pulse generation module U1B of the processing chip, and the capacitors C8, C9, and C10 are respectively connected between the gate driving power terminal and the gate driving reset terminal of each phase of the driving pulse generation module U1B; the state detection module U1C of the processing chip includes a DC bus overvoltage detection circuit, a brushless motor overcurrent circuit, and a processing chip overtemperature detection circuit. The DC bus overvoltage detection circuit inputs the sampled voltage to the voltage detection terminal of the processing chip; the brushless motor overcurrent detection circuit inputs the converted voltage value to the overcurrent detection terminal of the processing chip through the sampling resistor R32; the processing chip overtemperature detection circuit divides the voltage by the thermistor and the ordinary resistor, and then converts the temperature value into a voltage signal and inputs it to the overtemperature detection terminal.

6. The constant pressure water pump control system driven by a high voltage brushless motor according to any one of claims 1-5, characterized in that, The values of the gate resistors R20 and R21 are 10 - 150 Ω.

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