AC motor dust collector control circuit

Abstract

The invention relates to a control circuit of an alternating current motor dust collector. The control circuit comprises an MCU used for outputting a control signal; the main motor control circuit is used for starting, stopping and controlling the power of the main motor; the floor brush motor control circuit is used for controlling start and stop of a floor brush motor; the electrical isolation circuit is used for realizing isolation between an MCU control signal and a ground brush motor driving loop; the current sampling circuit is used for detecting current of the main motor and the ground brush motor; the voltage sampling circuit is used for detecting power supply voltage; the zero-crossing detection circuit is used for detecting a zero-crossing point of the power supply voltage; the rectification step-down circuit is used for converting alternating current into direct current and converting high-voltage direct current into low-voltage direct current; the rectification step-down circuit provides stable working voltage for the MUC through the voltage stabilization chip IC2. High voltage is processed in a non-isolation mode, the problems of high cost and size caused by using a transformer are avoided, the reliability equivalent to that of the transformer is maintained, current and voltage sampling is carried out, and accurate control over the output power of the main motor is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum cleaners, and in particular to an AC motor vacuum cleaner control circuit. Background Art

[0002] With the advancement of technology and the improvement of living standards, the types and functions of household appliances are becoming increasingly rich, among which vacuum cleaners have become one of the indispensable tools for household cleaning. Modern vacuum cleaners usually use AC motors as power sources to provide stable and powerful suction. However, traditional AC motor control circuits have some limitations and challenges.

[0003] Traditional vacuum cleaner control circuits often use transformers for electrical isolation and voltage conversion, which not only increases costs, but also makes the equipment bulky, which is not conducive to the miniaturization and portability of the product. Secondly, the use of transformers also increases the complexity and energy consumption of the circuit. In addition, traditional control circuits have safety hazards when handling high voltage electricity, and it is also difficult to achieve precise control of the motor, affecting the performance of the vacuum cleaner and user experience. Summary of the invention

[0004] To this end, the technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an AC motor vacuum cleaner control circuit that uses a non-isolated method to process high voltage electricity, avoiding the high cost and volume problems caused by the use of a transformer, while maintaining reliability comparable to that of a transformer, and performing current and voltage sampling to achieve precise control of the output power of the main motor.

[0005] In order to solve the above technical problems, the present invention provides an AC motor vacuum cleaner control circuit, comprising: MCU, used to output control signals; Main motor control circuit, used for starting and stopping the main motor and controlling its power; The floor brush motor control circuit is used to control the start and stop of the floor brush motor; The electrical isolation circuit is mainly used to isolate the MCU control signal from the ground brush motor drive circuit; A current sampling circuit is used to detect the current of the main motor; A voltage sampling circuit is used to detect the power supply voltage; A zero-crossing detection circuit is used to detect the zero-crossing point of the power supply voltage; The rectifier and step-down circuit is used to convert AC power into DC power, and at the same time convert high-voltage DC power into low-voltage DC power; the rectifier and step-down circuit provides a stable operating voltage for the MUC through the voltage regulator chip IC2.

[0006] In one embodiment of the present invention, the main motor control circuit includes a main motor, a bidirectional thyristor TR1, a current detection resistor R3, and an operational amplifier IC3B. The main motor is connected to the live wire L and the ground wire of the power supply; the bidirectional thyristor TR1 is used to receive the control signal of the MCU, adjust the power of the main motor, and control the power output of the main motor; the current detection resistor R3 is connected in series in the main motor circuit to convert the current signal into a voltage signal; the operational amplifier IC3B is connected to the current detection resistor R3 to amplify the voltage signal, and the amplified voltage signal is converted by the analog-to-digital conversion of the MCU to calculate the current value on R3.

[0007] In one embodiment of the present invention, a ground brush motor, a PNP transistor Q1, an optocoupler IC4 and a bidirectional thyristor TR2 are included. The ground brush motor is connected to the neutral line N and the ground line of the power supply. The PNP transistor Q1 is connected to the pin BR_MOTOR_DRIVER of the MCU and is used to receive a low-level signal from the MCU to turn on. The optocoupler IC4 emits light after receiving the turn-on signal of the PNP transistor Q1. The bidirectional thyristor TR2 receives the optocoupler IC4 signal to control the ground brush motor.

[0008] In one embodiment of the present invention, a key control circuit is further included for identifying different key operations; the key control circuit includes a key board CN1, and the key board CN1 is connected to AD_V_KEY of the MCU for detecting the voltage value on the key board to identify the key operation.

[0009] In one embodiment of the present invention, an overvoltage protection circuit is also included, and the overvoltage protection circuit includes a varistor ZD1, a varistor ZD2, and a varistor ZD3. One end of the varistor ZD1 is connected to the neutral line N, and the other end is connected to the live line L. One end of the varistor ZD2 is connected to the neutral line N, and the other end is connected to the 4th pin of the key board CN1; one end of the varistor ZD3 is connected to the neutral line N, and the other end is connected to the 7th pin of the key board CN1. When the external surge voltage exceeds the protection value of the varistor, the varistor will be turned on, clamping the voltage within a safe range, and protecting the internal circuit.

[0010] In one embodiment of the present invention, the electrical isolation circuit includes an optocoupler IC4 and a thyristor TR2, and the optocoupler IC4 includes a light-emitting diode LED and a photosensitive receiver; when the BR_MOTOR_DRIVER pin of the MCU outputs a low level, the light-emitting diode LED on the optocoupler IC4 emits light, and the photosensitive receiver is turned on after receiving the light signal, thereby controlling the bidirectional thyristor TR2 connected thereto. Optocoupler isolation is the main way to achieve electrical isolation. This design avoids the use of a transformer, thereby reducing cost and volume, while maintaining the safety and reliability of the circuit. Through optocoupler isolation, there is no direct electrical connection between the control signal of the MCU and the ground brush motor control circuit, so that the MCU at different potentials can control the ground brush motor.

[0011] In one embodiment of the present invention, the current sampling circuit includes a current detection resistor R2, a fuse F2, an inductor L3, and an operational amplifier IC3A. One end of the current detection resistor R2 is connected to the live wire L, and the other end is connected to the 4th pin of the key board CN1 through the fuse F2 and the inductor L3; the current sampling circuit R2 is used to detect current, the filter inductor L3 is used for filtering, the fuse F2 is used to protect the circuit in the event of overcurrent, and the operational amplifier IC3A is connected to the current detection resistor R2 to amplify the voltage signal across the current detection resistor R2; the output signal of the operational amplifier IC3A is filtered through a diode D11 and a resistor R33 to convert the fluctuating voltage value into a constant DC voltage.

[0012] In one embodiment of the present invention, the zero-crossing detection circuit includes a diode D7, a diode D8, a resistor R18 and a resistor R19, wherein the resistor R18 and the resistor R19 are connected to the Zero_Cross_TDO pin of the MCU as a voltage-dividing resistor, and the power supply voltage is divided into a lower voltage level for sampling by the Zero_Cross_TDO pin of the MCU; the diode D7 and the diode D8 cooperate with the resistor R18 and the resistor R19 to realize zero-crossing detection. Through the voltage division of the resistors R18 and R19 and the clamping of the diodes D7 and D8, it can be ensured that the voltage received by the Zero_Cross_TDO pin of the MCU is within a safe range, avoiding damage to the MCU due to excessive voltage. Through accurate zero-crossing detection, the MCU can control the power switch of the motor near the zero point of the voltage waveform to achieve accurate motor control.

[0013] In one embodiment of the present invention, the voltage sampling circuit includes resistors R9, R10, a resistor R11 and a diode D5, wherein the resistor R9 and the resistor R11 are connected in parallel, and the resistor R10 divides the voltage with the parallel R9 and R11; the diode D5 cooperates with R11 to clamp the voltage. When a negative voltage flows through the circuit, when the voltage at one end of the resistor R11 connected to the diode D5 is higher than the voltage at the other end, the diode D5 is turned on to clamp the voltage at a safe level.

[0014] In one embodiment of the present invention, the rectifier and step-down circuit includes an AC / DC conversion chip IC1, a diode D1, a diode D2, an inductor L1, a capacitor E1 and a capacitor E2. When the AC / DC conversion chip IC1 inherits pulse width modulation control, it and the power MOS tube are used to convert high-voltage DC power into low-voltage DC power; the diode D1 and the diode D2 are used to rectify and convert AC power into DC power, and the inductor L1, the capacitor E1 and the capacitor E2 are used for filtering and energy storage; when the power MOS tube of the AC / DC conversion chip IC1 is turned on, the current passes through the inductor L2, and the capacitors E3 and E4 are not charged. When the power MOS tube is turned off, the current in the inductor L2 forms a loop through the diode D3, the capacitors E3 and E4 to provide a working voltage for the AC / DC conversion chip IC1.

[0015] The above technical solution of the present invention has the following beneficial effects compared with the prior art: The AC motor vacuum cleaner control circuit described in the present invention processes high voltage electricity in a non-isolated manner, and uses a rectifier and step-down circuit to enable a voltage regulator chip to output a -5V voltage to power an MCU chip, thereby avoiding the high cost and volume problems caused by the use of a transformer, helping to reduce the volume of the vacuum cleaner control circuit and making the device more portable; at the same time, it maintains reliability comparable to that of a transformer, and through precise current and voltage sampling, it achieves precise control of the output power of the main motor, thereby improving the efficiency and performance of the motor, and further improves the energy efficiency of the motor by performing zero-crossing detection, thereby reducing the waste of electric energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0017] Figure 1 is a circuit diagram of an AC motor vacuum cleaner control circuit in a preferred embodiment of the present invention; Figure 2 It is a circuit diagram of the operational amplifier IC3A and peripheral circuits in the present invention; Figure 3 It is a circuit diagram of the operational amplifier IC3B and peripheral circuits in the present invention; DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0019] Reference Figure 1 As shown, an AC motor vacuum cleaner control circuit of the present invention comprises: MCU, used to output control signals; Main motor control circuit, used for starting and stopping the main motor and controlling its power; The floor brush motor control circuit is used to control the start and stop of the floor brush motor; The electrical isolation circuit is mainly used to isolate the MCU control signal from the ground brush motor drive circuit; A current sampling circuit is used to detect the current of the main motor; A voltage sampling circuit is used to detect the power supply voltage; A zero-crossing detection circuit is used to detect the zero-crossing point of the power supply voltage; The rectifier and step-down circuit is used to convert AC power into DC power, and at the same time convert high-voltage DC power into low-voltage DC power; the rectifier and step-down circuit provides a stable operating voltage for the MUC through the voltage regulator chip IC2.

[0020] Furthermore, the main motor control circuit includes a main motor, a bidirectional thyristor TR1, a current detection resistor R3, and an operational amplifier IC3B. The main motor is connected to the live wire L and the ground wire N of the power supply; the bidirectional thyristor TR1 is used to receive the control signal of the MCU, adjust the power of the main motor, and control the power output of the main motor; the current detection resistor R3 is connected in series in the main motor circuit to convert the current signal into a voltage signal; the operational amplifier IC3B is connected to the current detection resistor R3 to amplify the voltage signal, and the amplified voltage signal is converted by the analog-to-digital conversion of the MCU to calculate the current value on R3.

[0021] The positive and negative poles of the main motor are connected to the live wire L and the ground wire M+ through the three pins of the thyristor TR1. A resistor R3 is also connected between the two power lines. Therefore, the voltage difference flowing through the two ends of the resistor R3 is calculated and passed through the operational amplifier IC3B. At this time, it is a fluctuating voltage. The MCU samples through the pin I_MOTO_N_AD_TMS. The detected voltage value changes in real time, so the current value of the main motor calculated by the software also changes in real time. The actual current multiplied by the actual voltage can get the actual power. After the power is calculated, it can be compared with the set power. The actual power can be adjusted to the required power value by adjusting the conduction angle. The conduction angle can be controlled by the thyristor TR1. When the MCU detects the zero crossing point through the pin Zero_Cross_TDO, the delay time can be calculated. If the voltage waveform frequency is 50hz, then the entire half wave is 10ms. If it is delayed for 5ms before conduction, then only half of the work is done. The conduction angle is different, and the current generated will also be different. The main motor current is detected to calculate the power and to see the change in the conduction angle.

[0022] Furthermore, the main motor control circuit includes a ground brush motor, a PNP transistor Q1, an optocoupler IC4 and a bidirectional thyristor TR2. The ground brush motor is connected to the neutral line N and the ground line of the power supply. The PNP transistor Q1 is connected to the pin BR_MOTOR_DRIVER of the MCU and is used to receive a low-level signal from the MCU to turn on. The optocoupler IC4 emits light after receiving the turn-on signal of the PNP transistor Q1. The bidirectional thyristor TR2 receives the optocoupler IC4 signal to control the ground brush motor.

[0023] In addition, it also includes a key control circuit for identifying different key operations; the key control circuit includes a key board CN1, and the key board CN1 is connected to AD_V_KEY of the MCU for detecting the voltage value on the key board to identify the key operation.

[0024] In one embodiment of the present invention, an overvoltage protection circuit is also included, and the overvoltage protection circuit includes a varistor ZD1, a varistor ZD2, and a varistor ZD3. One end of the varistor ZD1 is connected to the neutral line N, and the other end is connected to the live line L. One end of the varistor ZD2 is connected to the neutral line N, and the other end is connected to the 4th pin of the key board CN1; one end of the varistor ZD3 is connected to the neutral line N, and the other end is connected to the 7th pin of the key board CN1. When the external surge voltage exceeds the protection value of the varistor, the varistor will be turned on, clamping the voltage within a safe range, and protecting the internal circuit.

[0025] The varistor ZD1 is mainly used to protect the circuit from damage in extreme weather such as thunderstorms; the other end of the varistor ZD3 is connected to the 7th pin of CN2, KEY; KEY is a key; if an electrostatic gun is used to hit the key directly, the varistor ZD3 can absorb static electricity. Only when the KEY key is pressed and the MCU detects that a key has been pressed, will it control the BR_MOTOR_DRIVER end to make the circuit conductive. The MCU's pin AD_V_KEY is the voltage value of the sampling point, and different keys have different corresponding voltage values.

[0026] The electrical isolation circuit in this embodiment includes an optocoupler IC4 and a thyristor TR2, wherein the optocoupler IC4 includes a light emitting diode LED and a photosensitive receiver; when the BR_MOTOR_DRIVER pin of the MCU outputs a low level, the light emitting diode LED on the optocoupler IC4 emits light, and the photosensitive receiver is turned on after receiving the light signal, thereby controlling the bidirectional thyristor TR2 connected thereto. Optocoupler isolation is the main way to achieve electrical isolation.

[0027] When the MCU's pin BR_MOTOR_DRIVER inputs a low level, the PNP transistor Q1 is turned on, and the collector (point c) outputs a high level of 5V, then the diode on the optocoupler IC4 lights up, and the phototransistor is turned on after receiving the light signal; the bidirectional thyristor TR2 will only be turned on when there is a voltage difference between its pins 1 and 3, and it can be turned on in both positive and negative directions. The voltage at one pin comes from the neutral line N, and the voltage at the 3rd pin comes from the 5V voltage that flows through after the optocoupler IC4 is turned on; through optocoupler isolation, there is no direct electrical connection between the control signal and the power supply, which reduces the risk of electric shock and electromagnetic interference and improves the stability of the circuit.

[0028] The current sampling circuit in this embodiment includes a current detection resistor R2, a fuse F2, an inductor L3, and an operational amplifier IC3A. One end of the current detection resistor R2 is connected to the live wire L, and the other end is connected to the 4th pin of the key board CN1 through the fuse F2 and the inductor L3; the current sampling circuit R2 is used to detect current, the filter inductor L3 is used for filtering, the fuse F2 is used to protect the circuit in the case of overcurrent, and the operational amplifier IC3A is connected to the current detection resistor R2 to amplify the voltage signal across the current detection resistor R2; the output signal of the operational amplifier IC3A is filtered through the diode D11 and the resistor R33 to convert the fluctuating voltage value into a constant DC voltage. The current flows through the ground brush motor, and then flows through the inductor L3 and the fuse F2, and then flows through the resistor R2. Therefore, the voltage signal across R2 is amplified by the operational amplifier IC3A, and then filtered by the diode D11 and the resistor R33, so that the fluctuating voltage value is converted into a constant DC voltage. The MCU can calculate the current of the ground brush motor by sampling the voltage at the I_BR_P_AD_TDI pin.

[0029] Inductor L3 is used for filtering when measuring EMC, and fuse F2 will blow after overcurrent to protect the circuit. Since pins 1 and 4 of keypad CN1 are externally connected to the brush motor, the current comes out through live wire L. When the voltage of live wire L is in the positive half axis, the voltage at the end of resistor R2 connected to live wire L is higher than the voltage at the other end. Conversely, the voltage at the end of resistor R2 connected to live wire L is lower than the voltage at the other end.

[0030] The voltage sampling circuit in this embodiment includes resistors R9, R10, a resistor R11 and a diode D5. The resistor R9 and the resistor R11 are connected in parallel, and the resistor R10 divides the voltage with the parallel R9 and R11; the diode D5 cooperates with R11 to clamp the voltage. When negative voltage flows through the circuit, when the voltage at one end of the resistor R11 connected to the diode D5 is higher than the voltage at the other end, the diode D5 is turned on to clamp the voltage at a safe level.

[0031] When the live wire L outputs a positive voltage, R10 divides the voltage with R9 and R11 connected in parallel, and the voltage AD_V obtains through the sampling resistor R10 can be used to calculate the total AC voltage between the neutral wire N and the live wire L.

[0032] Diode D5 is used when a negative voltage flows through it. The voltage at the end where resistor R11 and diode D5 are connected is higher than the voltage at the other end of resistor R11. If the voltage at the other end is 5V, the voltage at the end where resistor R11 and diode D5 are connected is (5-IR 11 ), the voltage sampled by MCU is lower than 5V; if the voltage at the other end is 5V, the voltage at the end where resistor R11 and diode D5 are connected is (5+IR 11 ), the voltage value sampled by MCU is higher than 5V, and the converted sampling value inside the chip will be inaccurate, and the voltage higher than 5V will also affect the chip; capacitor C7 and resistor R12 play a filtering role.

[0033] Further, the zero-crossing detection circuit includes a diode D7, a diode D8, a resistor R18 and a resistor R19, wherein the resistor R18 and the resistor R19 are connected to the Zero_Cross_TDO pin of the MCU as a voltage-dividing resistor, and the power supply voltage is divided into a lower voltage level for sampling by the Zero_Cross_TDO pin of the MCU; the diode D7 and the diode D8 cooperate with the resistor R18 and the resistor R19 to realize zero-crossing detection. Through the voltage division of the resistors R18 and R19 and the clamping of the diodes D7 and D8, it can be ensured that the voltage received by the Zero_Cross_TDO pin of the MCU is within a safe range, and the MCU is avoided from being damaged by excessive voltage. Through accurate zero-crossing detection, the MCU can control the power switch of the motor near the zero point of the voltage waveform to realize accurate motor control.

[0034] Furthermore, the rectifier and step-down circuit includes an AC / DC conversion chip IC1, a diode D1, a diode D2, an inductor L1, a capacitor E1 and a capacitor E2. When the AC / DC conversion chip IC1 inherits pulse width modulation control, it and the power MOS tube are used to convert high-voltage DC power into low-voltage DC power; the diode D1 and the diode D2 are used to rectify and convert AC power into DC power, and the inductor L1, the capacitor E1 and the capacitor E2 are used for filtering and energy storage; when the power MOS tube of the AC / DC conversion chip IC1 is turned on, the current passes through the inductor L2, and the capacitors E3 and E4 are not charged. When the power MOS tube is turned off, the current in the inductor L2 forms a loop through the diode D3, the capacitors E3 and E4 to provide a working voltage for the AC / DC conversion chip IC1.

[0035] When the live wire L output power supply is positive 220V and the neutral wire N output power supply voltage is negative 220V, according to the unidirectional conductivity of the diode, the power supply voltage output by the neutral wire N is cut off by the two diodes D1 and D2; when the live wire L output power supply voltage is negative 220V and the neutral wire N output power supply voltage is positive 220V, the voltage flows through the two diodes D1 and D2 to charge the capacitor E1, and at the same time, after flowing through the inductor L1, it will also charge the capacitor E2, so the two capacitors E1 and E2 always have voltage.

[0036] When the MOS tube inside IC1 is turned on, the current flows out through the inductor L2, and the capacitors E3 and E4 are not charged at this time; when the MOS tube is turned off instantly, because the current in the inductor cannot change suddenly, it will continue to flow. Therefore, when the MOS tube is turned off, the current will form a loop through the inductor L2, diode D3, and capacitor E3, and will also form a loop through the inductor L2, capacitor E4, and diode D4. Therefore, when the MOS tube is disconnected, capacitors E3 and E4 begin to charge, providing working voltage to the 4th pin VCC of the AC-DC conversion chip IC1, and the chip can work normally.

[0037] After the capacitor E4 is charged, there is voltage at both ends. Since the voltage regulator chip IC2 outputs a negative voltage, the 1st pin of the voltage regulator chip IC2 is equivalent to GND, so the output pin 3 is -5V output, resulting in the voltage at this point being 5V lower than GND. Taking this point as the reference, the voltage at GND is 5V. Because the point at which GND is located is connected to the live wire L, the voltage regulator chip IC2 can control its output voltage at the output voltage of the neutral wire L (V L -5) V, so no matter how the AC voltage changes, the voltage difference between the two ends of capacitor C6 can always maintain 5V to power the chip.

[0038] The filter inductor L1 is also the inductor of EMC filtering. Generally, if EMC is not considered, only one capacitor E1 is needed. Because of the filter inductor L1, the AC-DC conversion chip IC1 will obtain current from the capacitor E2 when it is not turned off. The AC-DC conversion chip IC1 can also be supplemented with power through the inductor L2, the diode D3 and the capacitor E3 in this circuit. Because the power of the capacitor is continuous DC, no sudden changes will occur under normal circumstances.

[0039] The AC motor vacuum cleaner control circuit based on the above structure can achieve the following functions: First, it can achieve the output of -5V voltage of the voltage regulator chip through the rectifier and step-down circuit without using a transformer to isolate the high voltage, and use this output point as the reference point (GND), 0V (V L ) as VCC to power the chip and ensure the normal operation of the chip; second, the current of the main motor and the ground brush motor is processed by the operational amplifier in a non-isolated manner and accurately sampled, so as to achieve precise control of the output power of the main motor and protect the ground brush motor from overcurrent; third, the button information is identified by voltage signal sampling; fourth, the DC high voltage is converted into DC low voltage through the chip IC1 and the inductor L2, and then the low voltage is converted into 5V voltage through the voltage regulator chip 78L05; fifth, the real-time power can be calculated through zero-crossing detection, and the target power can be achieved by controlling the thyristor and changing the conduction angle.

[0040] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. An AC motor vacuum cleaner control circuit, characterized in that: include: MCU, used to output control signals; Main motor control circuit, used for starting and stopping the main motor and controlling its power; The floor brush motor control circuit is used to control the start and stop of the floor brush motor; The electrical isolation circuit is mainly used to isolate the MCU control signal from the ground brush motor drive circuit; A current sampling circuit is used to detect the current of the main motor; A voltage sampling circuit is used to detect the power supply voltage; A zero-crossing detection circuit is used to detect the zero-crossing point of the power supply voltage; The rectifier and step-down circuit is used to convert AC power into DC power, and at the same time convert high-voltage DC power into low-voltage DC power; the rectifier and step-down circuit provides a stable operating voltage for the MUC through the voltage regulator chip IC2.

2. The AC motor vacuum cleaner control circuit according to claim 1, characterized in that: The main motor control circuit includes a main motor, a bidirectional thyristor TR1, a current detection resistor R3, and an operational amplifier IC3B. The main motor is connected to the live wire L and the ground wire of the power supply; the bidirectional thyristor TR1 is used to receive the control signal of the MCU, adjust the power of the main motor, and control the power output of the main motor; the current detection resistor R3 is connected in series in the main motor circuit to convert the current signal into a voltage signal; the operational amplifier IC3B is connected to the current detection resistor R3 to amplify the voltage signal, and the amplified voltage signal is converted by the analog-to-digital conversion of the MCU to calculate the current value on R3.

3. The AC motor vacuum cleaner control circuit according to claim 1, characterized in that: It includes a ground brush motor, a PNP transistor Q1, an optocoupler IC4 and a bidirectional thyristor TR2. The ground brush motor is connected to the neutral line N and the ground line of the power supply. The PNP transistor Q1 is connected to the pin BR_MOTOR_DRIVER of the MCU and is used to receive a low-level signal from the MCU to turn on. The optocoupler IC4 emits light after receiving the turn-on signal of the PNP transistor Q1. The bidirectional thyristor TR2 receives the optocoupler IC4 signal to control the ground brush motor.

4. The AC motor vacuum cleaner control circuit according to claim 1, characterized in that: It also includes a key detection circuit, which is used to identify different key operations; the key detection circuit includes a key board CN1, and the key board CN1 is connected to AD_V_KEY of the MCU to detect the voltage value on the key board to identify the key operation.

5. The AC motor vacuum cleaner control circuit according to claim 4, characterized in that: It also includes an overvoltage protection circuit, which includes a varistor ZD1, a varistor ZD2, and a varistor ZD3. One end of the varistor ZD1 is connected to the neutral line N, and the other end is connected to the live line L. One end of the varistor ZD2 is connected to the neutral line N, and the other end is connected to the 4th pin of the key board CN1; one end of the varistor ZD3 is connected to the neutral line N, and the other end is connected to the 7th pin of the key board CN1. When the external surge voltage exceeds the protection value of the varistor, the varistor will be turned on, clamping the voltage within a safe range, and protecting the internal circuit.

6. The AC motor vacuum cleaner control circuit according to claim 1, characterized in that: The electrical isolation circuit includes an optocoupler IC4 and a thyristor TR2, wherein the optocoupler IC4 includes a light-emitting diode LED and a photosensitive receiver; when the BR_MOTOR_DRIVER pin of the MCU outputs a low level, the light-emitting diode LED on the optocoupler IC4 emits light, and the photosensitive receiver is turned on after receiving the light signal, thereby controlling the bidirectional thyristor TR2 connected thereto.

7. The AC motor vacuum cleaner control circuit according to claim 1, characterized in that: The current sampling circuit includes a current detection resistor R2, a fuse F2, an inductor L3, and an operational amplifier IC3A. One end of the current detection resistor R2 is connected to the live wire L, and the other end is connected to the 4th pin of the keypad CN1 through the fuse F2 and the inductor L3; the current sampling circuit R2 is used to detect current, the filter inductor L3 is used for filtering, the fuse F2 is used to protect the circuit in the event of overcurrent, and the operational amplifier IC3A is connected to the current detection resistor R2 to amplify the voltage signal across the current detection resistor R2; the output signal of the operational amplifier IC3A is filtered through a diode D11 and a resistor R33 to convert the fluctuating voltage value into a constant DC voltage.

8. The AC motor vacuum cleaner control circuit according to claim 1, characterized in that: The voltage sampling circuit includes resistors R9, R10, a resistor R11 and a diode D5. The resistor R9 and the resistor R11 are connected in parallel, and the resistor R10 divides the voltage with the parallel R9 and R11; the diode D5 cooperates with R11 to clamp the voltage. When negative voltage flows through the circuit, when the voltage at one end of the resistor R11 connected to the diode D5 is higher than the voltage at the other end, the diode D5 is turned on to clamp the voltage at a safe level.

9. The AC motor vacuum cleaner control circuit according to claim 1, characterized in that: The zero-crossing detection circuit includes a diode D7, a diode D8, a resistor R18 and a resistor R19. The resistors R18 and R19 are connected to the Zero_Cross_TDO pin of the MCU as voltage-dividing resistors to divide the power supply voltage to a lower voltage level for sampling by the Zero_Cross_TDO pin of the MCU; the diodes D7 and D8 cooperate with the resistors R18 and R19 to realize zero-crossing detection.

10. The AC motor vacuum cleaner control circuit according to claim 1, characterized in that: The rectifier and step-down circuit includes an AC / DC conversion chip IC1, a diode D1, a diode D2, an inductor L1, a capacitor E1 and a capacitor E2. When the AC / DC conversion chip IC1 inherits pulse width modulation control, it and the power MOS tube are used to convert high-voltage DC power into low-voltage DC power; the diode D1 and the diode D2 are used to rectify and convert AC power into DC power, and the inductor L1, the capacitor E1 and the capacitor E2 are used for filtering and energy storage; when the power MOS tube of the AC / DC conversion chip IC1 is turned on, the current passes through the inductor L2, and the capacitors E3 and E4 are not charged. When the power MOS tube is turned off, the current in the inductor L2 forms a loop through the diode D3, the capacitors E3 and E4 to provide a working voltage for the AC / DC conversion chip IC1.

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