A variable frequency constant speed control circuit for an air purifier

Abstract

This utility model discloses a variable frequency constant speed control circuit for an air purifier, comprising: a rectifier and filter circuit, which rectifies and filters the input power supply voltage after suppressing common-mode interference; a flyback power supply circuit, which steps down the voltage output by the rectifier and filter circuit to a constant 12V output; a first step-down circuit, which steps down the 12V DC voltage output by the flyback power supply circuit to a constant 5V DC output; an IGBT module circuit, which receives control signals from a motor control chip and outputs current to drive the motor to rotate at a constant speed; a motor control chip, which inputs signals and outputs control signals to the IGBT module to drive the motor to rotate; and a main control chip, which is signal-connected to the motor control chip.

Description

Technical Field

[0001] This utility model relates to the field of motor control circuit technology, and in particular to a variable frequency constant speed control circuit for an air purifier. Background Technology

[0002] Air purifiers, also known as air cleaners or air purifiers, use a motor to circulate indoor air. The air that flows through the purifier is filtered and sterilized to make it fresh before it flows out; thus removing indoor air pollution and freshening the indoor air.

[0003] There are many types of air purifiers, and the functions they perform are generally similar, but their specific implementation and control methods are quite diverse. Different manufacturers have their own different control methods, and different control methods are implemented by different combinations of electronic components. Utility Model Content

[0004] The purpose of this invention is to provide a variable frequency constant speed control circuit for an air purifier. Using this control circuit, the motor rotation can be controlled, and the speed can be adjusted by a knob or signal input. At the same time, the motor can run at a constant speed after the speed is adjusted.

[0005] The above-mentioned technical objective of this utility model is achieved through the following technical solution: a variable frequency constant speed control circuit for a purifier, comprising a rectifier and filter circuit, wherein the rectifier and filter circuit rectifies and filters the input power supply voltage after suppressing common-mode interference; A flyback power supply circuit, wherein the flyback power supply circuit reduces the voltage output by the rectifier and filter circuit to a constant voltage output of 12V; The first step-down circuit reduces the 12V DC voltage output by the flyback power supply circuit to a 5V DC voltage output. The IGBT module circuit receives the control signal output by the motor control chip and outputs the current to drive the motor to rotate at a constant speed. A motor control chip, which takes input signals and outputs control signals to the IGBT module to drive the motor to rotate; The main control chip is connected to the motor control chip via signal transmission.

[0006] By adopting the above technical solution, the rectifier filter circuit, flyback power supply circuit and the first step-down circuit convert the power supply voltage into DC power to power the electronic devices. The motor control chip and IGBT module circuit drive the motor to rotate at a constant speed by frequency conversion. The main control chip communicates with the motor control chip and sends communication signals to control the operation of the frequency conversion motor. At the same time, the main control chip receives signals for real-time monitoring and alarm.

[0007] A further feature of this invention is that the rectifier and filter circuit includes a common-mode inductor L1, a rectifier bridge D2, and a transformer T1. The input terminals of the common-mode inductor L1 are respectively the live wire input terminal and the neutral wire input terminal. One end of the input terminal of the rectifier bridge D2 is connected to the output terminal of the common-mode inductor L1, and the other end of the input terminal of the rectifier bridge D2 is connected to the transformer T1.

[0008] A further feature of this invention is that the flyback power supply circuit includes a high-frequency transformer T2, a power chip U5, an optocoupler U4, and a Zener diode D9. The DRAIN pin of the power chip U5 is connected to the primary winding of the high-frequency transformer T2. The optocoupler U4 and the Zener diode D9 sample the voltage exceeding 12V output by the high-frequency transformer T2 and feed it back to the power chip U5.

[0009] A further feature of this invention is that the first step-down circuit is connected to the flyback power supply circuit to step down the 12V voltage output by the flyback power supply circuit to 5V output, and the first step-down circuit includes a step-down chip U6.

[0010] A further feature of this invention is that it includes a second step-down circuit, which is connected to the rectifier and filter circuit to step down the voltage output by the rectifier and filter circuit to a 15V output voltage.

[0011] A further feature of this invention is that the second step-down circuit is connected to a third step-down circuit, which steps down the 15V voltage to a 5V voltage output.

[0012] By adopting the above technical solution, a second step-down circuit and a third step-down circuit are used to generate 15V and 5V voltages, and multiple signal sources prevent interference from internal signal sources in the circuit.

[0013] A further feature of this invention is that it also includes an alarm circuit, which includes an alarm SC1 and a transistor Q1. The negative terminal of the alarm SC1 is connected to the collector of the transistor Q1, and the base of the transistor Q1 is connected to the main control chip U7.

[0014] A further feature of this invention is an asynchronous communication circuit, which includes chip U9 and chip U10. The 5V voltage output by the first step-down circuit and the 5V voltage output by the third step-down circuit are high-level signal sources. The asynchronous communication circuit transmits data signals between the main control chip and the motor control chip.

[0015] A further feature of this invention is that it includes a sterilization switch circuit, which includes a transistor Q3 and a relay. The collector of the transistor Q3 is connected to the negative terminal of the relay coil contact, the emitter of the transistor Q3 is connected to the ground point, and the base of the transistor Q3 is connected to a control chip. The control chip outputs a signal to control the transistor Q3 to conduct in order to control the relay to engage.

[0016] A further feature of this invention is that the sterilization switch circuit also includes an optocoupler U8, the input terminal of which is connected to a resistor R46, the output terminal of which is connected to a control chip, and the optocoupler U8 samples the current of the resistor R46 and outputs a signal to the control chip.

[0017] Compared with the prior art, the present invention has the following advantages: 1. The control circuit of the present invention can control the motor rotation by frequency conversion, and adjust the speed by frequency conversion through the knob or signal input, while maintaining a constant speed after the motor speed is adjusted; when the motor speed is affected by factors such as clogging of the air purifier filter, an alarm will be triggered; 2. Multiple signal sources are provided to prevent internal interference in the circuit, and a common mode inductor is provided in the rectifier and filter circuit to prevent external electromagnetic interference. Attached Figure Description

[0018] Figure 1 This is a block diagram of the variable frequency constant speed control circuit in the embodiment.

[0019] Figure 2 This is a schematic diagram of a PCB board printed with the frequency conversion constant speed control circuit in the embodiment.

[0020] Figure 3 This is a circuit diagram of the rectifier and filter circuit in the embodiment.

[0021] Figure 4 This is a circuit diagram of the flyback power supply circuit in the embodiment.

[0022] Figure 5 This is a circuit diagram of the first step-down circuit in the embodiment.

[0023] Figure 6 This is a circuit diagram of the IGBT module circuit in the embodiment.

[0024] Figure 7 This is a circuit diagram of the motor control chip in the embodiment.

[0025] Figure 8 This is the circuit schematic of the main control chip in the embodiment.

[0026] Figure 9 This is a circuit diagram of the second step-down circuit in the embodiment.

[0027] Figure 10 This is the circuit diagram of the third step-down circuit in the embodiment.

[0028] Figure 11 This is a circuit diagram of the alarm circuit in the embodiment.

[0029] Figure 12 This is a circuit diagram of the asynchronous communication circuit in the embodiment.

[0030] Figure 13 This is a circuit diagram of the sterilization switch circuit in the embodiment.

[0031] In the diagram: 1. Rectifier and filter circuit; 2. Flyback power supply circuit; 3. First step-down circuit; 4. IGBT module circuit; 5. Motor control chip; 6. Main control chip; 7. Second step-down circuit; 8. Third step-down circuit; 9. Alarm circuit; 10. Asynchronous communication circuit; 11. Sterilization switch circuit. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model. It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] This utility model discloses a variable frequency constant speed control circuit for an air purifier, such as... Figure 1 , Figure 2 As shown, this circuit is set on the printed circuit board as the main control circuit of the air purifier. The input end is connected to the power cord, and the output end is connected to the motor to provide constant speed drive for the motor inside the air purifier.

[0034] like Figure 1 As shown, a variable frequency constant speed control circuit for an air purifier includes a rectifier filter circuit 1, a flyback power supply circuit 2, a first step-down circuit 3, a motor control chip 5, an IGBT module circuit 4, and a main control chip 6.

[0035] The input terminal of the rectifier and filter circuit 1 is connected to the power supply line to suppress common-mode noise and rectify and filter the input power supply voltage to achieve a voltage output of 310V. The flyback power supply circuit 2 is connected to the rectifier and filter circuit 1 to convert the 310V voltage into a constant 12V output. The first step-down circuit 3 is connected to the flyback power supply circuit 2 to step down the 12V voltage to a 5V output. The motor control chip 5 and the IGBT module circuit 4 are connected. The motor control chip 5 receives control commands and outputs control signals to the IGBT module. The IGBT module circuit 4 receives signals and outputs current through high-speed switching of the switching transistor to drive the motor to rotate in a variable frequency manner.

[0036] The rectifier and filter circuit 1 rectifies and filters the input power supply voltage to a 310V DC voltage before outputting it. Products using this invention are universally compatible with both American and European standard voltages. No circuit changes are required. Simply plug and unplug a shorting cap at the port during production to increase the voltage multiplier, boosting the 110V voltage to 220V through capacitor multiplication, thus saving costs.

[0037] like Figure 3 In the specific embodiment, the rectifier and filter circuit 1 has an input voltage of 220V AC. A fuse F1, a varistor R1, a thermistor R2, a resistor R8, a resistor R9, and a capacitor C1 are connected between the power supply live wire input terminal TP-L and the power supply neutral wire input terminal TP-N. The power supply live wire input terminal TP-L and the power supply neutral wire input terminal TP-N are respectively connected to the input terminals IN1 and IN2 of the common mode inductor L1. The common mode inductor L1 filters out common mode noise in the circuit and suppresses electromagnetic radiation interference. The output terminal OUT1 of the common mode inductor L1 is connected to the rectifier bridge D2, and the output terminal OUT2 of the common mode inductor L1 is connected to the rectifier bridge D2. The rectifier bridge D2 outputs a DC voltage after rectification. A filter capacitor C2 is provided between the common mode inductor L1 and the rectifier bridge D2. Filter capacitors C33 and C7 are provided at the output of the rectifier bridge D2. The peak voltage of the 220V AC rectified power is 310V. After the filter capacitors are charged, the output voltage is a peak voltage of 310V.

[0038] A series capacitor pair C3 and C4 are connected in parallel at the input terminal of rectifier bridge D2, and another series capacitor pair C12 and C13 are connected in parallel at the output terminal of rectifier bridge D2. Connecting lines are provided between capacitors C3 and C4, and between capacitors C12 and C13, leading to port J35. This circuit design allows for compatibility with both US standard voltage 110V and European standard voltage 230V. In regions where the circuit is sold at 220V or European standard voltage 230V, ports J35 and J5 can be connected. When connected, it's equivalent to connecting capacitors C4 and C13 in parallel between the input and output terminals of rectifier bridge D2 to convert it to 310V voltage. In sales regions with a US standard voltage of 110V, remove the connection between port J35 and port J5. Connect capacitors C3 and C4 in parallel between the input and output terminals of rectifier bridge D2, and capacitors C12 and C13 in series. The maximum voltage is boosted from 110V to 220V by capacitors C3 and C4, and is also converted to 310V by rectifier bridge D2. The 310V voltage is stored in capacitors C12 and C13 and then output.

[0039] like Figure 3As shown, the output terminal OUT2 of the common mode inductor L1 is connected to the input terminal of the transformer T1. The output terminal of the transformer T1 is connected to one end of the input terminal of the rectifier bridge D2. The other end of the input terminal is connected to the analog ground point AGND. The output terminal of the rectifier bridge D2 is connected in parallel with capacitors C33 and C7.

[0040] like Figure 4 As shown, the flyback power supply circuit 2 takes in a 310V input voltage and steps it down to a constant 12V DC output voltage, which serves as the power supply for electronic components. The flyback power supply circuit 2 mainly includes a high-frequency transformer T2, a power chip U5, an optocoupler U4, and a Zener diode D9. Pin 1 of the primary winding of the high-frequency transformer T2 receives the 310V voltage, and pin 3 of the primary winding of the high-frequency transformer T2 is connected to the DRAIN pin of the power chip U5. The power chip U5 controls the input current in the primary winding of the high-frequency transformer T2. The frequency of the generated magnetic field is controlled to control the converted voltage value; pin 9 of the secondary winding of high-frequency transformer T2 is connected to the power supply ground point to anchor to zero potential, and pin 10 of the secondary winding of high-frequency transformer T2 outputs voltage; pin 5 of the auxiliary winding of high-frequency transformer T2 is connected in sequence to diode D6, resistor R16, capacitor C20, and signal ground point, and pin 4 of the auxiliary winding of high-frequency transformer T2 is grounded to anchor the electromotive force generated by the mutual inductance in the auxiliary winding, and the mutual inductance current generated in the auxiliary winding of high-frequency transformer T2 charges capacitor C20. The power supply chip U5's VDD pin is connected to capacitor C20, which provides power for U5's startup. Simultaneously, the positive terminal of capacitor C20, the output pin C of optocoupler U4, the output pin E of optocoupler U4, resistor R27, and the FB pin of power chip U5 are connected in sequence. The input terminal of optocoupler U4 is connected across resistor R26 to sample the current across R26. The secondary winding pin 10 of high-frequency transformer T2, resistors R25 and R26, Zener diode D9, and the power ground point are connected in series. Zener diode D9... The regulated voltage is 12V. When the output voltage of the secondary winding of the high-frequency transformer T2 is greater than 12V, the Zener diode D9 breaks down and conducts. A circuit is formed between pin 10 of the secondary winding of the high-frequency transformer T2, resistors R25 and R26, the Zener diode D9, and the power ground point. Current flows through resistor R26. The current in the sampling resistor R26 of the optocoupler U4 turns on the output terminal of the optocoupler U4. The FB pin of the power chip U5 receives a signal, thereby controlling the frequency of the current input to the primary winding of the high-frequency transformer T2 to stabilize the average output voltage at 12V. To ensure stable voltage output, one end of the secondary winding of the high-frequency transformer T2 is connected to diode D8, and capacitors C44, C5, and C52 are connected in parallel.

[0041] like Figure 4As shown, to accurately sample the feedback signal, a capacitor C34 is connected in parallel to the FB pin of the power chip U5; to stabilize the output voltage, a capacitor C19 and resistors R29 and R15 are connected in parallel across the primary winding of the high-frequency transformer T2, and a capacitor C51 is connected to one end of the primary winding of transformer T2. A diode D1 is connected to control the current direction; a capacitor C45 and a resistor R34 are connected to diode D8; in this embodiment, the specific model of transformer T2 is QLK-EE16-70.

[0042] like Figure 5 The first step-down circuit 3 includes a step-down chip U6. The step-down chip U6 takes a 12V input voltage and outputs a 5V voltage. At the output terminal, sampling resistors R53 and R54 are provided. The feedback pin FB of the step-down chip U6 is connected to the sampling resistor R54 to maintain the output voltage at 5V. The 5V voltage serves as the signal source for the main control chip 6 to receive signals. In this embodiment, the step-down chip U6 is model LGS5148.

[0043] Figure 6 This refers to IGBT module circuit 4, which includes IGBT module U1 and its auxiliary circuitry. Figure 7 Motor control chip 5 is connected to the IGBT module, specifically to UL, UH, VL, VH, WL, and WH signals, and to OPA1P, OPA3P, and OPA0P signals. It uses PWM signal output modulation and a three-phase four-bridge arm inverter circuit principle to output power to drive the motor. This is existing technology and will not be described here.

[0044] like Figure 8 The main control chip 6 shown is chip U7, model SC92F8003. The main control chip 6 is connected to the motor control chip 5. Specifically, the asynchronous communication circuit 10 is used for data signal transmission. At the same time, chip U7 receives signals to monitor the motor status in real time and alarms.

[0045] like Figure 9 , Figure 10 As shown, in order to effectively resist internal and external disturbances and prevent power signals from interfering with each other due to lack of isolation, which affects the constant speed drive of the motor, a second step-down circuit 7 and a third step-down circuit 8 are also provided in the control circuit. The second step-down circuit 7 includes a chip U3, and the third step-down circuit 8 includes a chip U11. The second step-down circuit 7 is connected to the rectifier and filter circuit 1 to convert the voltage to 15V and outputs it. The 15V voltage output by the second step-down circuit 7 provides power to the IGBT module U1. The chip U3 is model LNK304. The third step-down circuit 8 is connected to the second step-down circuit 7 to convert the 15V voltage to 5V and outputs it. The 5V voltage output by the third step-down circuit 8 provides power to the motor control chip 5.

[0046] like Figure 11 As shown, it also includes an alarm circuit 9, which includes an alarm SC1 and a transistor Q1. The positive terminal of the alarm SC1 is connected to a 12V power supply, which is the 12V voltage output by the flyback power supply circuit 2. The negative terminal of the alarm SC1 is connected to the collector of the transistor Q1. The base of the transistor Q1 is connected to the main control chip 6U7. The emitter of the transistor Q1 is connected to the ground point. The main control chip 6U7 outputs a signal to control the transistor Q1 to conduct, causing the alarm SC1 to sound an alarm.

[0047] like Figure 11 As shown, the signal transmission between the motor control chip 5 and the main control chip 6 adopts an asynchronous communication circuit 10. The asynchronous communication circuit 10 includes chip U9 and chip U10. The 5V voltage output by the first step-down circuit 3 and the 5V voltage output by the third step-down circuit 8 are used as high-level signal sources for signal transmission. Multiple signal sources are used to prevent interference from internal signal sources in the circuit. Both chip U9 and chip U10 adopt optocoupler-optotransistor of model EL817MC.

[0048] like Figure 12 As shown, a sterilization switch circuit 11 is also provided. The sterilization switch circuit 11 is controlled by the control chip to turn on or off to provide power to the sterilization component. For example, in this embodiment, the sterilization switch circuit 11 can be connected to a UV sterilization lamp. The sterilization switch circuit 11 turns on or off to provide power to the UV sterilization lamp so that the UV sterilization lamp can be turned on and operated normally. The sterilization switch circuit 11 includes a transistor Q3 and a relay. The input terminal of the relay main contact is connected to the live wire. The output terminal of the relay main contact is connected to the resistor R12 and then connected to the wiring port J2. The wiring port J2 is connected to the sterilization component. The input terminal of the relay coil contact is connected to a 12V voltage. The output terminal of the relay coil contact is connected to the collector of the transistor Q3. The emitter of the transistor Q3 is connected to the ground point. The base of the transistor Q3 is connected to the pin of the control chip. The control chip outputs a signal to control the transistor Q3 to conduct, thereby controlling the relay to be energized or de-energized.

[0049] The sterilization switch circuit 11 also includes a feedback circuit. The feedback circuit provides feedback to the control chip on whether the sterilization switch circuit 11 is powered normally. The feedback circuit includes an optocoupler U8. Resistors R48, R49, and R46 are connected in series at the output terminal of the relay main contact. The other end of resistor R46 is connected to the wiring port J2. Resistors R48 and R49 are large resistors. The live wire voltage is current-limited by resistors R48 and R49 to form a loop. Resistor R46 is a sampling resistor. The two ends of resistor R46 are connected to the input terminal of optocoupler U8. One end of the output terminal of optocoupler U8 is connected to a 5V voltage, and the other end is connected to the ground point. At the same time, the output terminal of optocoupler U8 is connected to a current-limiting resistor R50 and a sampling resistor R51. The other end of sampling resistor R51 is connected to the control chip. When the sampling resistor R51 outputs a high level, the sterilization switch circuit 11 is closed. When the sampling resistor R51 outputs a low level, the sterilization switch circuit 11 is open. Otherwise, the sterilization switch circuit 11 is faulty.

[0050] The above description is only a preferred embodiment of the present utility model. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of the present utility model patent application are included in the scope of the present utility model patent application.

Claims

1. A variable frequency constant speed control circuit for a purifier, characterized in that: include, The rectifier and filter circuit (1) rectifies and filters the input power supply voltage after suppressing common-mode interference; The flyback power supply circuit (2) reduces the voltage output by the rectifier filter circuit (1) to a constant voltage output of 12V. The first step-down circuit (3) steps down the 12V DC voltage output by the flyback power supply circuit (2) to a 5V DC voltage output. IGBT module circuit (4), the IGBT module circuit (4) receives the control signal output by the motor control chip (5) and outputs the current to drive the motor to rotate at a constant speed; Motor control chip (5), the motor control chip (5) inputs signals and runs to output control signals to the IGBT module to drive the motor to rotate; The main control chip (6) is connected to the motor control chip (5) via signal.

2. The variable frequency constant speed control circuit for a purifier according to claim 1, characterized in that: The rectifier and filter circuit (1) includes a common-mode inductor L1, a rectifier bridge D2 and a transformer T1. The input terminals of the common-mode inductor L1 are the power supply live wire input terminal and the power supply neutral wire input terminal, respectively. One end of the input terminal of the rectifier bridge D2 is connected to the output terminal of the common-mode inductor L1, and the other end of the input terminal of the rectifier bridge D2 is connected to the transformer T1.

3. The variable frequency constant speed control circuit for a purifier according to claim 1, characterized in that: The flyback power supply circuit (2) includes a high-frequency transformer T2, a power chip U5, an optocoupler U4, and a Zener diode D9. The DRAIN pin of the power chip U5 is connected to the primary winding of the high-frequency transformer T2. The optocoupler U4 and the Zener diode D9 sample the voltage output of the high-frequency transformer T2 exceeding 12V and feed it back to the power chip U5.

4. The variable frequency constant speed control circuit for a purifier according to claim 1, characterized in that: The first step-down circuit (3) is connected to the flyback power supply circuit (2) to step down the 12V voltage output by the flyback power supply circuit (2) to 5V output. The first step-down circuit (3) includes a step-down chip U6.

5. The variable frequency constant speed control circuit for a purifier according to claim 1, characterized in that: It also includes a second step-down circuit (7), which is connected to the rectifier filter circuit (1) to step down the voltage output by the rectifier filter circuit (1) to a 15V voltage output.

6. The variable frequency constant speed control circuit for a purifier according to claim 5, characterized in that: The second step-down circuit (7) is connected to a third step-down circuit (8), which steps down the 15V voltage to a 5V voltage output.

7. The variable frequency constant speed control circuit for a purifier according to claim 1, characterized in that: It also includes an alarm circuit (9), which includes an alarm SC1 and a transistor Q1. The negative terminal of the alarm SC1 is connected to the collector of the transistor Q1, and the base of the transistor Q1 is connected to the main control chip (6) U7.

8. The variable frequency constant speed control circuit for a purifier according to claim 6, characterized in that: The asynchronous communication circuit (10) includes chip U9 and chip U10. The 5V voltage output by the first step-down circuit (3) and the 5V voltage output by the third step-down circuit (8) are high-level signal sources. The asynchronous communication circuit (10) transmits data signals between the main control chip (6) and the motor control chip (5).

9. The variable frequency constant speed control circuit for a purifier according to claim 1, characterized in that: It also includes a sterilization switch circuit (11), which includes a transistor Q3 and a relay. The collector of the transistor Q3 is connected to the negative terminal of the relay coil contact, the emitter of the transistor Q3 is connected to the ground point, and the base of the transistor Q3 is connected to the control chip. The control chip outputs a signal to control the transistor Q3 to conduct in order to control the relay to engage.

10. The variable frequency constant speed control circuit for a purifier according to claim 9, characterized in that: The sterilization switch circuit (11) also includes an optocoupler U8. The input terminal of the optocoupler U8 is connected to a resistor R46, and the output terminal of the optocoupler U8 is connected to a control chip. The optocoupler U8 samples the current of the resistor R46 and outputs a signal to the control chip.

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