AC motor dust collector control circuit

Abstract

The utility model 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. According to the utility model, a non-isolation mode is adopted to process high voltage, the problems of high cost and volume 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 of the output power of the main motor is realized.

Description

Technical Field

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

[0002] With technological advancements and rising living standards, household appliances are becoming increasingly diverse and versatile. Vacuum cleaners have become an indispensable tool for household cleaning. Modern vacuum cleaners typically use AC motors as their power source, providing stable and powerful suction. However, traditional AC motor control circuits present several 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 device bulky, hindering product miniaturization and portability. Furthermore, the use of transformers increases circuit complexity and energy consumption. Furthermore, traditional control circuits pose safety risks when handling high voltages and struggle to achieve precise motor control, impacting vacuum cleaner performance 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 existing technology 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 brought by the use of transformers, while maintaining reliability comparable to that of transformers, and performing current and voltage sampling to achieve precise control of the output power of the main motor.

[0005] To solve the above technical problems, the present invention provides an AC motor vacuum cleaner control circuit, comprising:

[0006] MCU, used to output control signals;

[0007] Main motor control circuit, used to start and stop the main motor and control its power;

[0008] The floor brush motor control circuit is used to control the start and stop of the floor brush motor;

[0009] The electrical isolation circuit is mainly used to isolate the MCU control signal from the ground brush motor drive circuit;

[0010] Current sampling circuit, used to detect the current of the main motor;

[0011] A voltage sampling circuit is used to detect the power supply voltage;

[0012] A zero-crossing detection circuit is used to detect the zero-crossing point of the power supply voltage;

[0013] 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.

[0014] 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. The amplified voltage signal is converted by the MCU to a digital signal, and the current value on R3 can be calculated.

[0015] 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.

[0016] 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.

[0017] One embodiment of the present invention further includes an overvoltage protection circuit comprising varistors ZD1, ZD2, and ZD3. Varistor ZD1 has one end connected to the neutral line N and the other end connected to the live line L. Varistor ZD2 has one end connected to the neutral line N and the other end connected to pin 4 of keypad CN1. Varistor ZD3 has one end connected to the neutral line N and the other end connected to pin 7 of keypad CN1. When an external surge voltage exceeds the protection level of the varistor, the varistor conducts, clamping the voltage within a safe range and protecting the internal circuitry.

[0018] 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 photosensor; 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 photosensor 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.

[0019] 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 fourth pin of the keypad CN1 through the fuse F2 and the inductor L3. The current sampling circuit R2 is used to detect current, the inductor L3 is used for filtering, and the fuse F2 is used to protect the circuit in the event of overcurrent. 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 by a diode D11 and a resistor R33 to convert the fluctuating voltage value into a constant DC voltage.

[0020] In one embodiment of the present invention, the zero-crossing detection circuit includes a diode D7, a diode D8, and resistors R18 and R19. The resistors R18 and R19 act as voltage dividers connected to the Zero_Cross_TDO pin of the MCU, dividing 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 work in conjunction with the resistors R18 and R19 to implement zero-crossing detection. The voltage division by resistors R18 and R19 and the clamping by diodes D7 and D8 ensure that the voltage received by the Zero_Cross_TDO pin of the MCU is within a safe range, preventing damage to the MCU due to excessive voltage. Through accurate zero-crossing detection, the MCU can control the motor power switch near the zero point of the voltage waveform, achieving precise motor control.

[0021] In one embodiment of the present invention, the voltage sampling circuit includes resistors R9, R10, a resistor R11, and a diode D5. The resistors R9 and R11 are connected in parallel, and the resistor R10 divides the voltage by the parallel connection of R9 and R11. The diode D5 cooperates with R11 to act as a voltage clamp. When a negative voltage flows through the circuit, if the voltage at one end connecting the resistor R11 and the diode D5 is higher than the voltage at the other end, the diode D5 is turned on, clamping the voltage to a safe level.

[0022] In one embodiment of the present invention, the rectifier and step-down circuit includes an AC / DC converter chip IC1, a diode D1, a diode D2, an inductor L1, a capacitor E1, and a capacitor E2. When the AC / DC converter chip IC1 inherits pulse width modulation control, it and the power MOS transistor are used to convert high-voltage DC power into low-voltage DC power. The diodes D1 and D2 are used to rectify the AC power and convert it into DC power. The inductor L1, capacitor E1, and capacitor E2 are used for filtering and energy storage. When the power MOS transistor of the AC / DC converter chip IC1 is turned on, current flows through the inductor L2, and capacitors E3 and E4 are not charged. When the power MOS transistor is turned off, the current in the inductor L2 forms a loop through the diode D3, capacitors E3, and E4, providing an operating voltage for the AC / DC converter chip IC1.

[0023] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0024] The AC motor vacuum cleaner control circuit described in the present invention processes high voltage electricity in a non-isolated manner. Through a rectifier and step-down circuit, the voltage regulator chip outputs a -5V voltage to power the MCU chip, 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 main motor output power, thereby improving the efficiency and performance of the motor. In addition, the energy efficiency of the motor is improved by performing zero-crossing detection, thereby reducing energy waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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.

[0026] Figure 1 is a circuit diagram of an AC motor vacuum cleaner control circuit in a preferred embodiment of the present invention;

[0027] Figure 2 is a circuit diagram of the operational amplifier IC3A and peripheral circuits in the present invention;

[0028] Figure 3is a circuit diagram of the operational amplifier IC3B and peripheral circuits in the present invention; DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0030] Reference Figure 1 As shown, an AC motor vacuum cleaner control circuit of the present invention includes:

[0031] MCU, used to output control signals;

[0032] Main motor control circuit, used to start and stop the main motor and control its power;

[0033] The floor brush motor control circuit is used to control the start and stop of the floor brush motor;

[0034] The electrical isolation circuit is mainly used to isolate the MCU control signal from the ground brush motor drive circuit;

[0035] Current sampling circuit, used to detect the current of the main motor;

[0036] A voltage sampling circuit is used to detect the power supply voltage;

[0037] A zero-crossing detection circuit is used to detect the zero-crossing point of the power supply voltage;

[0038] 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.

[0039] 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. The amplified voltage signal is converted by the analog-to-digital conversion of the MCU to calculate the current value on R3.

[0040] 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, respectively. A resistor R3 is also connected between the two power lines. Therefore, the voltage difference across the resistor R3 is calculated and passed through the operational amplifier IC3B. At this time, it is a fluctuating voltage. The MCU samples it through the pin I_MOTO_N_AD_TMS. The detected voltage value changes in real time, and therefore the main motor current value calculated by the software also changes in real time. The actual current multiplied by the actual voltage can be used to obtain 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 through the pin Zero_Cross_TDO, it can calculate the delay time. If the voltage waveform frequency is 50Hz, then the entire half-wave is 10ms. If the conduction is delayed for 5ms before conduction, only half of the work is done. Different conduction angles will also cause different currents. The main motor current is detected to calculate the power and to use it to observe the change in the conduction angle.

[0041] 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.

[0042] 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 the AD_V_KEY of the MCU for detecting the voltage value on the key board to identify the key operation.

[0043] One embodiment of the present invention further includes an overvoltage protection circuit comprising varistors ZD1, ZD2, and ZD3. Varistor ZD1 has one end connected to the neutral line N and the other end connected to the live line L. Varistor ZD2 has one end connected to the neutral line N and the other end connected to pin 4 of keypad CN1. Varistor ZD3 has one end connected to the neutral line N and the other end connected to pin 7 of keypad CN1. When an external surge voltage exceeds the protection level of the varistor, the varistor conducts, clamping the voltage within a safe range and protecting the internal circuitry.

[0044] Varistor ZD1 is primarily used to protect the circuit from damage during extreme weather conditions such as thunderstorms. The other end of varistor ZD3 is connected to pin 7 (KEY) of CN2. KEY is a key. If an anti-static gun were to strike the key directly, varistor ZD3 would absorb the static electricity. Only when the KEY key is pressed does the MCU detect a key press and control the BR_MOTOR_DRIVER terminal to complete the circuit. The MCU's AD_V_KEY pin samples the voltage at this point; different keys correspond to different voltage values.

[0045] The electrical isolation circuit in this embodiment includes an optocoupler IC4 and a triac (TRIAC) TR2. The optocoupler IC4 includes a light-emitting diode (LED) and a photosensor. When the MCU's BR_MOTOR_DRIVER pin outputs a low level, the LED on the optocoupler IC4 illuminates. The photosensor receives the light signal and turns on, thereby controlling the connected triac TR2. Optocoupler isolation is the primary method for achieving electrical isolation.

[0046] When a low level is input to the MCU's pin BR_MOTOR_DRIVER, the PNP transistor Q1 is turned on and the collector (point c) outputs a high level of 5V. The diode on the optocoupler IC4 then emits light, 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. It can be turned on in both forward and reverse directions. The voltage at one pin comes from the neutral line N, and the voltage at pin 3 comes from the 5V voltage flowing 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, thereby reducing the risk of electric shock and electromagnetic interference and improving the stability of the circuit.

[0047] The current sampling circuit in this embodiment includes a current sensing resistor R2, a fuse F2, an inductor L3, and an operational amplifier IC3A. One end of the current sensing resistor R2 is connected to the live wire L, and the other end is connected to pin 4 of the keypad CN1 through the fuse F2 and inductor L3. The current sampling circuit R2 is used to detect current, the inductor L3 is used for filtering, and the fuse F2 is used to protect the circuit in the event of overcurrent. The operational amplifier IC3A is connected to the current sensing resistor R2 to amplify the voltage signal across the current sensing resistor R2. The output signal of the operational amplifier IC3A is filtered by a diode D11 and a resistor R33, converting the fluctuating voltage value into a constant DC voltage. The current flows through the brush motor, passes 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, converting the fluctuating voltage value into a constant DC voltage. The MCU can calculate the brush motor current by sampling the voltage at the I_BR_P_AD_TDI pin.

[0048] Inductor L3 is used for filtering during EMC testing, and fuse F2 will blow in the event of an overcurrent condition, protecting the circuit. Because pins 1 and 4 of keypad CN1 are externally connected to the grounded motor, current flows through live wire L. When the voltage on 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.

[0049] The voltage sampling circuit in this embodiment includes resistors R9, R10, a resistor R11, and a diode D5. The resistors R9 and R11 are connected in parallel, and the resistor R10 divides the voltage by the parallel connection of R9 and R11. The diode D5 and R11 cooperate to act as a voltage clamp. When negative voltage flows through the circuit, if the voltage at one end connecting the resistor R11 and the diode D5 is higher than the voltage at the other end, the diode D5 turns on, clamping the voltage to a safe level.

[0050] When the live wire L outputs a positive voltage, R10 and the parallel-connected R9 and R11 divide the voltage. The voltage AD_V obtains through the sampling resistor R10 and the total AC voltage between the neutral wire N and the live wire L can be calculated.

[0051] Diode D5 is used to make the voltage at the end of resistor R11 connected to diode D5 higher than the voltage at the other end of resistor R11 when negative voltage flows through it. If the voltage at the other end is 5V, the voltage at the end of resistor R11 connected to diode D5 is (5-IR 11 ), the voltage sampled by the MCU is lower than 5V; if the voltage at the other end is 5V, the voltage at the end where the resistor R11 and the diode D5 are connected is (5+IR 11 ), the voltage value sampled by the 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.

[0052] Furthermore, the zero-crossing detection circuit includes a diode D7, a diode D8, and resistors R18 and R19. The resistors R18 and R19 act as voltage dividers connected to the Zero_Cross_TDO pin of the MCU, dividing 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 work together with the resistors R18 and R19 to implement zero-crossing detection. The voltage division of resistors R18 and R19 and the clamping of diodes D7 and D8 ensure that the voltage received by the Zero_Cross_TDO pin of the MCU is within a safe range, preventing 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, achieving precise motor control.

[0053] Furthermore, the rectifier and step-down circuit includes an AC / DC converter chip IC1, a diode D1, a diode D2, an inductor L1, a capacitor E1, and a capacitor E2. When pulse width modulation is integrated within the AC / DC converter chip IC1, it and the power MOS transistor are used to convert high-voltage DC power into low-voltage DC power. The diodes D1 and D2 are used to rectify AC power and convert it into DC power. The inductor L1, capacitor E1, and capacitor E2 are used for filtering and energy storage. When the power MOS transistor of the AC / DC converter chip IC1 is turned on, current flows through the inductor L2, and capacitors E3 and E4 are not charged. When the power MOS transistor is turned off, the current in the inductor L2 forms a loop through the diode D3, capacitors E3, and E4, providing an operating voltage for the AC / DC converter chip IC1.

[0054] When the power supply output of the live wire L is positive 220V and the power supply output voltage of the neutral wire N 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 power supply output voltage of the live wire L is negative 220V and the power supply output voltage of the neutral wire N 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. Therefore, the two capacitors E1 and E2 always have voltage.

[0055] When the MOS tube inside IC1 is turned on, current flows out through inductor L2, and 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 inductor L2, diode D3, and capacitor E3, and will also form a loop through inductor L2, capacitor E4, and diode D4. Therefore, when the MOS tube is disconnected, capacitors E3 and E4 begin to charge, providing operating voltage to the fourth pin VCC of the AC-DC conversion chip IC1, and the chip can work normally.

[0056] After capacitor E4 is charged, there is voltage at both ends. Since the voltage regulator chip IC2 outputs a negative voltage, pin 1 of the voltage regulator chip IC2 is equivalent to GND, so the output pin 3 is -5V, 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 where GND is located is connected to the live wire L, the voltage regulator chip IC2 can control its output voltage to 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.

[0057] The filter inductor L1 is also the inductor for EMC filtering. Generally, if EMC is not considered, only one capacitor E1 is needed. Because of the filter inductor L1, the AC-DC converter chip IC1 will obtain current from the capacitor E2 when it is not shut down. The AC-DC converter chip IC1 can also be replenished with power through the inductor L2, diode D3 and capacitor E3 in this circuit. Because the power of the capacitor is continuous DC, no sudden changes will occur under normal circumstances.

[0058] The AC motor vacuum cleaner control circuit based on the above structure can achieve the following functions: First, it can achieve the output of the voltage regulator chip -5V voltage 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 its normal operation; second, the current of the main motor and the ground brush motor are 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 sampling the voltage signal; 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.

[0059] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present 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 to start and stop the main motor and control 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; Current sampling circuit, 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. The amplified voltage signal is converted by the MCU to a digital signal, and the current value on R3 can be calculated.

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 control circuit, which is used to identify different key operations; the key control circuit includes a key board CN1, and the key board CN1 is connected to the 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 keypad 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 keypad CN1; when an external surge voltage exceeds the protection value of the varistor, the varistor will be turned on, clamping the voltage within a safe range, thereby 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. The optocoupler IC4 includes a light-emitting diode (LED) and a photosensor. 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 photosensor is turned on after receiving the light signal, thereby controlling the bidirectional thyristor TR2 connected to it.

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 fourth pin of the keypad CN1 through the fuse F2 and the inductor L3. The current sampling circuit R2 is used to detect current, the inductor L3 is used for filtering, and the fuse F2 is used to protect the circuit in the event of overcurrent. 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 by the diode D11 and the 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 resistors R9 and R11 are connected in parallel, and the resistor R10 divides the voltage by the parallel connection of R9 and R11. The diode D5 and R11 cooperate to act as a voltage clamp. When negative voltage flows through the circuit, if the voltage at one end connecting the resistor R11 and the diode D5 is higher than the voltage at the other end, the diode D5 turns on, clamping the voltage to 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, and 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 divider 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 implement 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 converter chip IC1, a diode D1, a diode D2, an inductor L1, capacitors E1, and E2. When pulse width modulation is integrated within the AC / DC converter chip IC1, it and the power MOS transistor are used to convert high-voltage DC power into low-voltage DC power. The diodes D1 and D2 are used to rectify AC power into DC power, and the inductor L1, capacitors E1, and capacitors E2 are used for filtering and energy storage. When the power MOS transistor of the AC / DC converter chip IC1 is turned on, current flows through the inductor L2, and capacitors E3 and E4 are not charged. When the power MOS transistor is turned off, the current in the inductor L2 forms a loop through the diode D3, capacitors E3, and E4, providing an operating voltage for the AC / DC converter chip IC1.

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