Double-voltage adaptive rectification PFC (Power Factor Correction) circuit structure and electric flame stove

Abstract

The invention discloses a double-voltage adaptive rectification PFC (Power Factor Correction) circuit structure and an electric flame stove. The double-voltage adaptive rectification PFC circuit structure comprises an EMI (Electro-Magnetic Interference) filtering unit, a voltage doubling rectification unit, a full-bridge rectification unit, a circuit switching control unit, a startup protection unit and a power factor correction unit. According to the circuit switching control unit, through conversion of full-bridge rectification or voltage-multiplying rectification, adaptability to commercial power of two different voltages is achieved; according to the power-on protection unit, when 220V mains supply is input, after the circuit voltage is stabilized, the relay RLY2 is completely switched on, and soft start protection is achieved; according to the invention, the MOS tube Q1 / Q2 is alternately connected and disconnected in a time sequence, so that the inductor L2 stores energy or discharges, the capacitor C22 is charged or discharged, the power factor correction unit outputs stable high-voltage electricity to a rear-end circuit or a load, when the MOS tube Q2 is connected, the resistance is zero, the superposed high-voltage electricity is transmitted to the rear-end circuit when the potential of the inductor L2 discharges, and low-loss energy conversion is realized.

Description

Technical Field

[0001] This invention specifically relates to an electric flame stove. Background Technology

[0002] An electric flame stove is a novel flame-generating method. It uses two different electrodes to generate an electric field by high-voltage breakdown of a gas stream (high resistance). The gas (high resistance) flows and collides with electrons in the electric field, ionizing the gas molecules and forming plasma (low resistance). This plasma has a temperature of over 1000 degrees Celsius and is blown out of the nozzle by the gas stream to heat the cookware. Currently, electric flame stoves on the market are also called electric fire stoves, electric fire starter stoves, electric flame stoves, electric combustion stoves, electric open flame stoves, plasma stoves, etc. All of these stoves use the working principle of high-voltage breakdown to excite plasma for heating cookware.

[0003] Currently available electric flame cooktops are only compatible with 220V-240V voltages. For the 110V AC mains power used in the United States and Japan, a separate circuit system needs to be developed. Using two sets of electric flame cooktop circuit molds not only increases production and R&D costs but also complicates production management.

[0004] In addition, the impedance of the electric flame stove load changes at high frequency, frequently switching between "airflow (high resistance) - plasma (low resistance) - airflow (high resistance) - plasma (low resistance)," which places high demands on circuit stability and electromagnetic compatibility.

[0005] Therefore, this invention develops an electric flame stove circuit that can adapt to both 220V-240V high voltage and 110V low voltage in different countries, and can also adapt to the application environment of high-frequency impedance changes of the load during the operation of the electric flame stove. Summary of the Invention

[0006] To overcome the shortcomings mentioned above, the present invention aims to provide a technical solution that can solve the above problems.

[0007] A dual-voltage adaptive rectification PFC circuit structure for electric flame stoves includes: an EMI filter unit, a voltage doubler rectifier unit, a full-bridge rectifier unit, a circuit switching control unit, a power-on protection unit, and a power factor correction unit. The circuit switching control unit includes a relay RLY1, a MOSFET Q3, and a Zener diode ZD1. One end of the coil of the relay RLY1 is connected to the power supply terminal, and the other end of the coil of the relay RLY1 is connected to the gate of the MOSFET Q3. The source of the MOSFET Q3 is grounded, and the drain of the MOSFET is connected to the cathode of the Zener diode ZD1 through a resistor R7. The moving contact of the relay RLY1 is connected to the positive input terminal of the power factor correction unit through the power-on protection unit, the first stationary contact of the relay RLY1 is connected to the positive output terminal of the voltage doubler rectifier unit, and the second stationary contact of the relay RLY1 is connected to the positive output terminal of the full-bridge rectifier unit. Preferably, the voltage doubler rectifier unit is composed of diodes D1 / D2 and capacitors C5 / C6. The positive output terminal formed by the cathode of diode D1 and capacitor C5 is connected to the first stationary contact of relay RLY1. The negative output terminal formed by the anode of diode D2 and capacitor C6 is connected to the negative input terminal of the power factor correction unit. The common node of the other end of capacitor C6 and the other end of capacitor C5, and the common node of the anode of diode D1 and the cathode of diode D2 are respectively connected to the two output terminals of the EMI filter unit. Preferably, the full-bridge rectifier unit is a full-bridge structure composed of diodes D3 / D4 / D5 / D6. The common node between the anode of diode D3 and the cathode of diode D4 is connected to one of the output terminals of the EMI filter unit, the common node between the anode of diode D5 and the cathode of diode D6 is connected to the other output terminal of the EMI filter unit, the positive output terminal formed by connecting the cathodes of diodes D3 and D5 is connected to the second stationary contact of relay RLY1, and the negative output terminal formed by connecting the anodes of D5 and D6 is connected to the negative input terminal of the power factor correction unit. Preferably, the power-on protection unit includes a relay RLY2 and a resistor R7. The first common node of the relay RLY2 and the resistor R7 is connected to the moving contact of the relay RLY1, and the first common node of the relay RLY2 and the resistor R7 is connected to the power factor correction unit. Preferably, the EMI filtering unit includes a common-mode inductor L1, capacitors C1 / C2 / C3 / C4, and resistor R3; the input terminal of the common-mode inductor L1 is connected to an external AC power interface CN1 / CN2, and the input terminal of the common-mode inductor L1 is also connected to the two ends of capacitor C2 and resistor R3 respectively; the two output terminals of the common-mode inductor L1 are connected to the two ends of capacitor C1. Preferably, the power factor correction unit includes an inductor L2, a MOSFET Q1, a MOSFET Q2, and a capacitor C22. The first end of the inductor L2 is connected to the power-on protection unit, the second end of the inductor L2 is connected to the common node of the source of MOSFET Q1 and the source of MOSFET Q2, respectively, the drain of MOSFET Q2 is connected to one end of the capacitor C22, and the other end of the capacitor C22 is grounded. Preferably, the power factor correction unit further includes a diode D11, the anode of which is connected to the power-on protection unit, and the cathode of which is connected to the common node of capacitor C22 and the drain of MOSFET Q2. Preferably, the power factor correction unit further includes a control chip U2 and a control chip U3; the output pin of the control chip U2 is connected to the input pin of the control chip U3 through a drive resistor R10, and the two output terminals of the control chip U3 are connected to the gate of MOSFET Q1 and the gate of MOSFET Q2 through drive resistors R14 / R18 respectively. Preferably, the detection pin of the control chip U2 is connected to the positive output terminal of the power factor correction unit through feedback resistors R23 / R24 / R25; The present invention also discloses an electric flame stove, which includes the PFC circuit structure with dual voltage adaptation rectification as described in any of the above claims.

[0008] Compared with the prior art, the advantages of the present invention are: The circuit switching control unit of this invention achieves adaptability to two different mains voltages through the conversion between full-bridge rectification and voltage doubler rectification; When the power-on protection unit of this invention is powered by 220V AC mains, after the circuit voltage stabilizes, the relay RLY2 is fully turned on to achieve "soft start" protection. The power factor correction unit of this invention uses the alternating switching of MOSFETs Q1 / Q2 to enable inductor L2 to store / discharge energy and capacitor C22 to charge / discharge, thereby enabling the power factor correction unit to output a stable high voltage to the back-end circuit or load. When MOSFET Q2 is turned on, it has zero resistance, allowing the high voltage superimposed on the potential of inductor L2 during discharge to be delivered to the back-end circuit, achieving "low-loss" energy conversion. Control chip U2 controls the duty cycle of the PWM drive signal and outputs the PWM drive signal to control chip U3. It also adjusts the timing of the output signals of the two output pins of control chip U3, so that the alternating switching timing of MOSFET Q1 and MOSFET Q2 is precisely controlled. This "corrects" the input current, which may have been distorted, into a sine wave in phase with the voltage, and ultimately maximizes the power factor.

[0009] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1This is a schematic diagram illustrating the working principle of the present invention. Detailed Implementation

[0012] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0014] Furthermore, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0015] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0016] Please see Figure 1 In this embodiment of the invention, a PFC circuit structure with dual voltage adaptive rectification is used for an electric flame stove. The structure includes: an EMI filter unit 100, a voltage doubler rectifier unit 200, a full-bridge rectifier unit 300, a circuit switching control unit 400, a power-on protection unit 500, and a power factor correction unit 600.

[0017] In the first embodiment, the EMI filter unit 100 includes a common-mode inductor L1, capacitors C1 / C2 / C3 / C4, and resistor R3; the input terminal of the common-mode inductor L1 is connected to the external AC power interface CN1 / CN2, and the input terminal of the common-mode inductor L1 is also connected to the two ends of capacitor C2 and resistor R3 respectively, and the two output terminals of the common-mode inductor L1 are connected to the two ends of capacitor C1.

[0018] The working process of EMI filter unit 100: After the external mains power (110V or 220VAC) is input through interface CN1 / CN2, it first enters EMI filter unit 100; common mode inductor L1 suppresses common mode interference, capacitors C1 / C2 / C3 / C4 filter out differential mode interference, and finally outputs "purified" AC power to the subsequent rectification unit; when the power is off, resistor R3 is used to discharge static electricity from capacitors C1 / C2 to prevent internal static electricity from injuring the human body.

[0019] In the second embodiment, the circuit switching control unit 400 includes a relay RLY1, a MOSFET Q3, and a Zener diode ZD1. One end of the coil of relay RLY1 is connected to the power supply terminal, and the other end of the coil is connected to the gate of MOSFET Q3. The source of MOSFET Q3 is grounded, and the drain of MOSFET Q3 is connected to the cathode of Zener diode ZD1 through resistor R7. The moving contact of relay RLY1 is connected to the positive input terminal of power factor correction unit 600 through power-on protection unit 500. The first stationary contact of relay RLY1 is connected to the positive output terminal of voltage doubler rectifier unit 200, and the second stationary contact of relay RLY1 is connected to the positive output terminal of full-bridge rectifier unit 300. The Zener diode ZD1 has a withstand voltage of 300V.

[0020] In addition, the power-on protection unit 500 includes a relay RLY2 and a resistor R7. The first common node of the relay RLY2 and the resistor R7 is connected to the moving contact of the relay RLY1, and the first common node of the relay RLY2 and the resistor R7 is connected to the power factor correction unit 600.

[0021] The circuit switching control unit 400, the voltage doubler rectifier unit 200, and the full-bridge rectifier unit 300 form a dual-voltage rectifier topology switching circuit. The specific working principle of this dual-voltage rectifier topology switching circuit is as follows: When a 110V AC mains input is applied, a 155V voltage is formed at the front end of the Zener diode ZD1, which fails to break down the Zener diode ZD1. Since the gate of the MOSFET Q3 does not receive a driving voltage, the MOSFET Q3 is in an open circuit state, and the coil of the relay RLY1 does not generate current. At this time, the moving contact and the first stationary contact of the relay RLY1 are closed, the voltage doubler rectifier unit 200 works, and the rectification of diodes D1 / D2 and the "charge and discharge superposition" of capacitors C5 / C6 double the 110V AC power to approximately 310V DC power.

[0022] When powered on with 220V AC mains, the moving contact and first stationary contact of relay RLY1 remain closed at the moment of power-on. At this time, the voltage doubler rectifier unit 200 outputs approximately 620V DC. Relay RLY2 conducts with a delay, limiting the initial current and voltage division through resistor R7 to prevent large current and high voltage from directly impacting the PFC unit. Simultaneously, a 310V voltage is formed in front of Zener diode ZD1, directly breaking down Zener diode ZD1. This causes MOSFET Q3 to receive a voltage lower than 5-10V, turning on MOSFET Q3 and generating current in the coil of relay RLY1. This causes the moving contact and first stationary contact of relay RLY1 to open, and the moving contact and second stationary contact of relay RLY1 to close. The full-bridge rectifier unit 300 rectifies the 220V AC to approximately 310V DC and supplies it to the downstream circuit. After the circuit voltage stabilizes, relay RLY2 is fully turned on, achieving "soft start" protection.

[0023] In the third embodiment, the power factor correction unit 600 includes an inductor L2, MOSFETs Q1 and Q2, a diode D11, a capacitor C22, and a diode D11. The first end of the inductor L2 is connected to the power-on protection unit 500, and the second end of the inductor L2 is connected to the common node of the source of MOSFET Q1 and the source of MOSFET Q2. The drain of MOSFET Q2 is connected to one end of the capacitor C22, and the other end of the capacitor C22 is grounded. The anode of the diode D11 is connected to the power-on protection unit 500, and the cathode of the diode D11 is connected to the common node of the capacitor C22 and the drain of MOSFET Q2.

[0024] When MOSFET Q1 is turned on and MOSFET Q2 is turned off, the DC voltage output by the power-on protection unit 500 flows to ground through inductor L2 and MOSFET Q1. Electrical energy is stored in inductor L2 in the form of "magnetic energy". At this time, diode D11 is cut off due to reverse bias. Output capacitor C22 relies on its stored electrical energy to maintain a 380V DC power supply for the downstream circuit. At the same time, the presence of diode D11 ensures that the downstream voltage will not drop below 310V due to MOSFET Q2 being turned off, achieving a "minimum 310V" voltage safety net.

[0025] When MOSFET Q1 is off and MOSFET Q2 is on, inductor L2 generates a reverse induced electromotive force, which, combined with a 310V DC voltage, outputs at least 380V DC voltage through MOSFET Q2 to maintain power supply to the downstream circuitry and simultaneously charge capacitor C22. When MOSFET Q2 is on, its resistance is close to 0Ω, resulting in almost no energy loss. This ensures that the 380V high voltage can be efficiently transferred to C22 and the downstream circuitry, achieving a "low-loss, high-voltage" energy conversion.

[0026] The power factor correction unit 600 also includes control chip U2 and control chip U3. The output pin of control chip U2 is connected to the input pin of control chip U3 through drive resistor R10. The two output terminals of control chip U3 are connected to the gates of MOSFET Q1 and MOSFET Q2 through drive resistors R14 / R18, respectively. Control chip U2 acquires the output voltage feedback signal (divided by R23 / R24 / R25), compares it with the internal reference voltage, and generates a PWM drive signal. This signal is transmitted to control chip U3 through drive resistor R10. Control chip U3 then controls the gates of MOSFETs Q1 and Q2 through drive resistors R14 and R18, respectively, to achieve precise timing control of the alternating on / off of Q1 and Q2.

[0027] The detection pin of control chip U2 is connected to the positive output terminal of power factor correction unit 600 through feedback resistors R23 / R24 / R25. If the output voltage is higher than 380V, control chip U2 reduces the duty cycle (shortening the on-time of MOSFET Q1 and reducing the energy stored in inductor L2), causing the superimposed voltage to drop; if the output voltage is lower than 380V, control chip U2 increases the duty cycle (extending the on-time of MOSFET Q1 and increasing the energy stored in inductor L2), causing the superimposed voltage to rise. Ultimately, through this closed-loop control, the output voltage is stabilized at 380V, providing a reliable high-voltage DC power supply to the back-end circuit of the electric flame stove.

[0028] The working principle of the power factor correction unit 600 is as follows: like Figure 1 As shown, the output of the pre-stage rectifier unit (voltage doubler rectifier unit 200 or full-bridge rectifier unit 300) is a pulsating DC voltage. The sampling pin of the control chip U2 detects the phase and amplitude changes of the pulsating DC voltage in real time through the sampling resistor R8, thereby obtaining the waveform characteristics of the original mains voltage. The current of the inductor L2 is sampled through the sampling resistor R9, and the current signal of the inductor L2 is fed back to the current detection pin of the control chip U2. The control chip U2 compares the input voltage phase signal with the inductor current signal in real time. If the phase of the inductor current lags behind the phase of the input voltage, or if the ratio of the amplitude to the voltage amplitude deviates from the sinusoidal law, the control chip U2 will immediately adjust the duty cycle of the PWM drive signal and adjust the timing of the output signals of the two output pins of the control chip U3 through the PWM drive signal. This ensures that the switching timing of MOSFETs Q1 and Q2 is precisely controlled. In each PWM cycle, the conduction time (duty cycle) of MOSFET Q1 changes linearly with the instantaneous value of the input voltage, so that the peak current of inductor L2 strictly follows the instantaneous waveform of the input voltage. This "corrects" the potentially distorted input current into a sine wave in phase with the voltage, ultimately maximizing the power factor (close to 1).

[0029] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A PFC circuit structure with dual voltage-adaptive rectification for use in an electric flame stove, characterized in that, include: EMI filter unit, voltage doubler rectifier unit, full-bridge rectifier unit, circuit switching control unit, power-on protection unit, power factor correction unit; The circuit switching control unit includes a relay RLY1, a MOSFET Q3, and a Zener diode ZD1. One end of the coil of the relay RLY1 is connected to the power supply terminal, and the other end of the coil of the relay RLY1 is connected to the gate of the MOSFET Q3. The source of the MOSFET Q3 is grounded, and the drain of the MOSFET Q3 is connected to the cathode of the Zener diode ZD1 through a resistor R7. The moving contact of the relay RLY1 is connected to the positive input terminal of the power factor correction unit through the power-on protection unit. The first stationary contact of the relay RLY1 is connected to the positive output terminal of the voltage doubler rectifier unit. The second stationary contact of the relay RLY1 is connected to the positive output terminal of the full-bridge rectifier unit.

2. The PFC circuit structure with dual voltage-adaptive rectification according to claim 1, characterized in that, The voltage doubler rectifier unit consists of diodes D1 / D2 and capacitors C5 / C6. The positive output terminal formed by the cathode of diode D1 and capacitor C5 is connected to the first stationary contact of relay RLY1. The negative output terminal formed by the anode of diode D2 and capacitor C6 is connected to the negative input terminal of the power factor correction unit. The common node of the other end of capacitor C6 and the other end of capacitor C5, and the common node of the anode of diode D1 and the cathode of diode D2 are respectively connected to the two output terminals of the EMI filter unit.

3. The PFC circuit structure with dual voltage-adaptive rectification according to claim 1, characterized in that, The full-bridge rectifier unit is a full-bridge structure composed of diodes D3 / D4 / D5 / D6. The common node between the anode of diode D3 and the cathode of diode D4 is connected to one of the output terminals of the EMI filter unit. The common node between the anode of diode D5 and the cathode of diode D6 is connected to the other output terminal of the EMI filter unit. The positive output terminal formed by connecting the cathodes of diodes D3 and D5 is connected to the second stationary contact of relay RLY1. The negative output terminal formed by connecting the anodes of D5 and D6 is connected to the negative input terminal of the power factor correction unit.

4. The PFC circuit structure with dual voltage-adaptive rectification according to claim 1, characterized in that, The power-on protection unit includes a relay RLY2 and a resistor R7. The first common node of the relay RLY2 and the resistor R7 is connected to the moving contact of the relay RLY1. The first common node of the relay RLY2 and the resistor R7 is connected to the power factor correction unit.

5. The PFC circuit structure with dual voltage-adaptive rectification according to claim 1, characterized in that, The EMI filtering unit includes a common-mode inductor L1, capacitors C1 / C2 / C3 / C4, and resistor R3. The input terminal of the common-mode inductor L1 is connected to an external AC power interface CN1 / CN2. The input terminal of the common-mode inductor L1 is also connected to the two ends of capacitor C2 and resistor R3, respectively. The two output terminals of the common-mode inductor L1 are connected to the two ends of capacitor C1.

6. The PFC circuit structure with dual voltage-adaptive rectification according to claim 1, characterized in that, The power factor correction unit includes an inductor L2, a MOSFET Q1, a MOSFET Q2, and a capacitor C22. The first end of the inductor L2 is connected to the power-on protection unit, and the second end of the inductor L2 is connected to the common node of the source of MOSFET Q1 and the source of MOSFET Q2. The drain of MOSFET Q2 is connected to one end of the capacitor C22, and the other end of the capacitor C22 is grounded.

7. The PFC circuit structure with dual voltage-adaptive rectification according to claim 1, characterized in that, The power factor correction unit also includes a diode D11, the anode of which is connected to the power-on protection unit, and the cathode of which is connected to the common node of capacitor C22 and the drain of MOSFET Q2.

8. The PFC circuit structure with dual voltage-adaptive rectification according to claim 1, characterized in that, The power factor correction unit also includes control chip U2 and control chip U3; the output pin of control chip U2 is connected to the input pin of control chip U3 through drive resistor R10, and the two output terminals of control chip U3 are connected to the gate of MOSFET Q1 and the gate of MOSFET Q2 through drive resistors R14 / R18 respectively.

9. The PFC circuit structure with dual voltage-adaptive rectification according to claim 8, characterized in that, The detection pin of the control chip U2 is connected to the positive output terminal of the power factor correction unit through feedback resistors R23 / R24 / R25.

10. An electric flame stove, characterized in that, The electric flame stove includes the PFC circuit structure with dual voltage adaptation rectification as described in any one of claims 1 to 9.

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