CN110890836A - PFC circuit with variable switching frequency and household appliance - Google Patents
PFC circuit with variable switching frequency and household appliance Download PDFInfo
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- CN110890836A CN110890836A CN201911104367.7A CN201911104367A CN110890836A CN 110890836 A CN110890836 A CN 110890836A CN 201911104367 A CN201911104367 A CN 201911104367A CN 110890836 A CN110890836 A CN 110890836A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Abstract
The invention provides a PFC circuit with variable switching frequency and household electrical appliance equipment, wherein the circuit comprises a variable frequency control circuit, a PFC switching circuit and a PFC control chip; the PFC switch circuit is connected with a switch control interface of the PFC control chip and outputs a corresponding PFC switch control signal according to the received control signal, and the PFC switch control signal is used for controlling the PFC control chip to be turned on or turned off; the frequency conversion control circuit is connected with a frequency configuration interface of the PFC control chip, and outputs a switching frequency signal with the same period as the PWM signal according to the received PWM signal, wherein the switching frequency signal is used for controlling the working frequency of the PFC control chip. The invention can avoid the problem that the switching noise interference energy of the power switching tube under a certain fixed frequency is concentrated in a fixed frequency section in the conventional PFC circuit, and can disperse the switching noise energy of the power switching tube in a wider frequency range, so that the maximum noise interference value of a product is effectively reduced.
Description
Technical Field
The invention relates to the technical field of PFC circuits, in particular to a PFC circuit with variable switching frequency and household electrical appliance equipment.
Background
The PFC (power Factor correction) means "power Factor correction", the power Factor is generally used to characterize the utilization degree of power and the pollution degree of a load to a power grid, and the PFC circuit is mainly used to improve harmonics and reduce the pollution of the load to the power grid.
The PFC circuit scheme mainly applied to the existing major power products mainly adopts a continuous Conduction mode ccm (continuous Conduction mode), and the working mode PFC circuit is characterized by high power and is a mainstream application scheme of the existing household electrical appliances such as the variable frequency air conditioner, and the like, and the scheme has the disadvantage that when the PFC circuit works, the switching frequency of a power switching tube generally works at a certain fixed frequency value, as shown in fig. 1, fig. 1 is a fixed frequency control PFC scheme block diagram of the existing technical scheme, wherein U1 is a PFC control chip, an R1 resistor is used for configuring the switching frequency of the PFC control chip, and other peripheral circuits are common circuit structures in the PFC control circuit. In this case, the fixed frequency is assumed to be 40 kHz. Fig. 2 to 5 are test curves and test values of terminal disturbance voltage and disturbance power in an EMI test of a product application according to a conventional fixed frequency control technical scheme, wherein a highest test value of a full test frequency band is-0.47 dB. Therefore, when the switching frequency of the power switching tube works at a certain fixed frequency value, the energy of the switching noise interference of the power switching tube is concentrated near the switching frequency of the power switching tube and the related fixed frequency, so that the EMI interference value of the related frequency point is higher, the product is difficult to pass the EMI authentication test, more complex EMI resistance measures are required, and finally, the product development difficulty and cost are improved.
Disclosure of Invention
The present invention is directed to overcome the above problems and to provide a variable switching frequency PFC circuit and a household electrical appliance.
The embodiment of the invention provides a PFC circuit with variable switching frequency, which comprises a frequency conversion control circuit, a PFC switching circuit and a PFC control chip;
the PFC switch circuit is connected with a switch control interface of the PFC control chip and outputs a corresponding PFC switch control signal according to a received control signal, and the PFC switch control signal is used for controlling the PFC control chip to be turned on or turned off;
and the frequency conversion control circuit is connected with a frequency configuration interface of the PFC control chip, and outputs a switching frequency signal with the same period as the PWM signal according to the received PWM signal, wherein the switching frequency signal is used for controlling the working frequency of the PFC control chip.
Optionally, the variable frequency control circuit includes a first resistor R1, a second resistor R2, a transistor Q1 and a capacitor C1;
the collector of the transistor Q1 is connected with one end of the second resistor R2, the base of the transistor Q1 is connected with the PWM signal output end of the microcontroller, the emitter of the transistor Q1 is grounded, the other end of the second resistor R2 is connected with the frequency configuration interface of the PFC control chip, one ends of the first resistor R1 and the capacitor C1 are respectively connected with the other end of the second resistor R2, and the other ends of the first resistor R1 and the capacitor C1 are respectively grounded.
Optionally, the variable frequency control circuit includes a first resistor R1, a second resistor R2, a multi-channel analog switch chip, and a capacitor C1;
one end of the first resistor R1 and one end of the second resistor R2 are respectively connected with input ports of a first channel and a second channel of the multi-channel analog switch chip, the other end of the first resistor R1 and the other end of the second resistor R2 are connected with a frequency configuration interface of the PFC control chip, a control port of the multi-channel analog switch chip is connected with a PWM signal output end of the microcontroller, an output port of the multi-channel analog switch chip is grounded, one end of the capacitor C1 is connected with the other end of the first resistor R1, the other end of the capacitor C1 is grounded, and the multi-channel analog switch chip respectively controls the input ports of the corresponding channels to be conducted with output ports according to high-low level signals input by the control port.
Optionally, the variable frequency control circuit comprises a first resistor R1, a second resistor R2, a relay circuit and a capacitor C1, wherein the relay circuit comprises a relay drive circuit and a relay;
one end of the first resistor R1 and one end of the second resistor R2 are respectively connected with a frequency configuration interface of the PFC control chip, the other end of the second resistor R2 is connected with a first contact of the relay, the other end of the first resistor R1 is grounded, the control end of the relay is connected with the output end of the relay driving circuit, the input end of the relay driving circuit is connected with the PWM signal output end of the microcontroller, the second contact of the relay is grounded, the capacitor C1 is arranged at two ends of the first resistor R1 in parallel, and the relay controls the connection or disconnection of the first contact and the second contact according to the output signal of the relay driving circuit.
Optionally, the capacitance value of the capacitor C1 is 100 pF.
Optionally, the frequency variation range of the switching frequency signal is 1-4 kHz.
Optionally, the frequency variation range of the switching frequency signal is 2 kHz.
Optionally, the switch frequency signal has a value range of 10 to 100 kHz.
Optionally, the upper limit value of the switching frequency signal is 40kHz, and the lower limit value of the switching frequency signal is 38 kHz.
In addition, the embodiment of the invention also provides household electrical appliance equipment, and the household electrical appliance equipment comprises the PFC circuit with the variable switching frequency.
The PFC circuit with the variable switching frequency and the household appliance provided by the embodiment of the invention adopt the PFC control scheme with the variable switching frequency, can avoid the problem that the switching noise interference energy of a power switching tube under a certain fixed frequency in the conventional PFC circuit is concentrated in a fixed frequency section, can disperse the switching noise energy of the power switching tube in a wider frequency range, and can effectively reduce the maximum noise interference value of a product. Furthermore, when the household appliance with the PFC circuit with the variable switching frequency is used for EMI test, the maximum switching noise interference value is effectively reduced by 8-10 dB compared with the maximum noise interference value of the original fixed frequency scheme, and the product development difficulty and cost are effectively reduced.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
fig. 1 is a schematic diagram of a fixed frequency control PFC scheme according to the prior art;
FIG. 2 is a terminal disturbance voltage test curve of the prior art fixed frequency control solution in an EMI test of a product application;
FIG. 3 is a terminal disturbance voltage test value in an EMI test of a product application according to a conventional fixed frequency control technical scheme;
FIG. 4 is a terminal disturbance power test curve of the prior art fixed frequency control solution in an EMI test of a product application;
FIG. 5 is a terminal disturbance power test value in an EMI test of a product application according to a conventional fixed frequency control technical scheme;
fig. 6 is a schematic structural diagram of a PFC circuit with a variable switching frequency according to an embodiment of the present invention;
fig. 7 is a terminal disturbance voltage test curve of the PFC circuit with variable switching frequency in the EMI test of the product application according to the embodiment of the present invention;
fig. 8 is a terminal disturbance voltage test value of the PFC circuit with variable switching frequency in the EMI test of the product application according to the embodiment of the present invention;
fig. 9 is a terminal disturbance power test curve of the PFC circuit with variable switching frequency in the EMI test of the product application according to the embodiment of the present invention;
fig. 10 is a terminal disturbance power test value of a PFC circuit with a variable switching frequency in an EMI test of a product application according to an embodiment of the present invention;
fig. 11 is a schematic structural diagram of a PFC circuit with a variable switching frequency according to another embodiment of the present invention;
fig. 12 is a schematic structural diagram of a PFC circuit with a variable switching frequency according to another embodiment of the present invention;
fig. 13 is a schematic structural diagram of a PFC circuit with a variable switching frequency according to another embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The PFC circuit aims to solve the problem that the working frequency of a power switching tube of a PFC circuit scheme adopting a CCM working mode in the prior art can only be unchanged at a certain fixed frequency value. The invention provides a variable switching frequency PFC control scheme, which controls the working frequency of a PFC control chip in a software PWM (pulse width modulation) mode, realizes the variable switching frequency of a PFC circuit power switching tube, can prevent the switching noise interference energy of the PFC circuit power switching tube under a certain fixed frequency from concentrating on a fixed frequency section, but disperses the switching noise energy of the power switching tube in a wider frequency range, so that the maximum switching noise interference value of a product applying the scheme is effectively reduced by 8-10 dB compared with the maximum noise interference value of the original fixed frequency scheme after an EMI (electro-magnetic interference) test.
Fig. 6 schematically shows a structural diagram of a PFC circuit with a variable switching frequency according to an embodiment of the present invention. Referring to fig. 6, the PFC circuit with variable switching frequency according to the embodiment of the present invention includes a frequency conversion control circuit 10, a PFC switching circuit 20, and a PFC control chip 30;
the PFC switch circuit 20 is connected to the switch control interface of the PFC control chip 30, and outputs a corresponding PFC switch control signal according to the received control signal, where the PFC switch control signal is used to control the on/off of the PFC control chip 30;
and the frequency conversion control circuit 10 is connected with the frequency configuration interface of the PFC control chip 30, and outputs a switching frequency signal having the same period as the PWM signal according to the received PWM signal, where the switching frequency signal is used to control the operating frequency of the PFC control chip 30.
The PFC circuit with the variable switching frequency provided by the embodiment of the invention can avoid the problem that the switching noise interference energy of a power switching tube under a certain fixed frequency is concentrated in a fixed frequency section in the conventional PFC circuit, and can disperse the switching noise energy of the power switching tube in a wider frequency range, so that the maximum noise interference value of a product is effectively reduced.
The frequency variation range of the switching frequency signal is 1-4 kHz, and preferably, the frequency variation range of the switching frequency signal is 2 kHz. The value range of the switching frequency signal is 10-100 kHz, preferably, the upper limit value of the switching frequency signal is 40kHz, and the lower limit value of the switching frequency signal is 38 kHz.
Fig. 7 to fig. 10 are test curves and test values of terminal disturbance voltage and disturbance power of the PFC circuit with variable switching frequency in the EMI test of the product application, where the highest test value in the full test frequency band is-11.27 dB.
In one embodiment, as shown in fig. 11, the variable frequency control circuit includes a first resistor R1, a second resistor R2, a transistor Q1, and a capacitor C1; the collector of the transistor Q1 is connected to one end of the second resistor R2, the base of the transistor Q1 is connected to the PWM signal output end of the microcontroller, the emitter of the transistor Q1 is grounded, the other end of the second resistor R2 is connected to the frequency configuration interface of the PFC control chip, one ends of the first resistor R1 and the capacitor C1 are connected to the other end of the second resistor R2, and the other ends of the first resistor R1 and the capacitor C1 are grounded.
In this embodiment, the capacitance value of the capacitor C1 is 100 pF.
The PFC control chip applied in the embodiment of the present invention has a working mode of a Current Continuous Mode (CCM), and the chip includes a frequency configuration interface that can configure a switching frequency of the chip through an external device, such as an OS port shown in fig. 6, where the OS port is externally connected with a resistor having a certain resistance value, so as to configure a corresponding switching frequency.
In the embodiment of the present invention, as shown in fig. 11, a resistor R1, a resistor R2, a transistor Q1, and a capacitor C1 constitute a circuit for implementing variable frequency control, wherein one end of the resistor R1, the resistor R2, and the end of the capacitor C1 are connected to a frequency configuration port of a PFC control chip, and a control end of the capacitor Q1 is connected to a microcontroller, such as a PWM output port of an MCU/DSP. When the transistor Q1 is turned off, the impedance of Q1 is infinite, the total resistance value of Q1 connected in series with R2 and then connected in parallel with R1 is still close to R1, which is equivalent to the resistance to ground of the OS frequency setting port of the PFC control chip mainly being the resistor R1, so the switching frequency f1 of the PFC control chip is mainly determined by the resistance value of R1; when the transistor is turned on, Q1 is low impedance, which is equivalent to the total resistance value of the ground impedance of the OS frequency setting port of the PFC control chip after Q1 is connected in series with R2 and then connected in parallel with R1, so the switching frequency f2 of the PFC control chip is determined by the resistances of R1 and R2 and the turn-on voltage drop of Q1.
When the PWM output end of the MCU/DSP outputs a switching signal with the frequency f, Q1 connected with the PWM output end of the MCU/DSP performs switching action according to the frequency f, so that the impedance of the OS frequency setting end of the PFC control chip to the ground also changes according to the frequency f period, the switching frequency of the PFC control chip changes periodically according to the frequency f between the frequency f1 and the frequency f2, and finally the PFC control chip is indirectly controlled through the PWM output signal of the MCU/DSP to realize variable switching frequency control.
For a specific PFC control chip, the variation range of the variable switching frequency is determined by the resistance values of resistors R1 and R2 and the conduction voltage drop of a transistor Q1, the working efficiency and the EMI suppression effect of a PFC circuit in practical application are comprehensively considered, the variation range of the switching frequency is generally designed to be 2-4 kHz, and the variation range of the switching frequency is designed to be 2kHz in the embodiment; the frequency change period is determined by the PWM signal frequency output by the MCU/DSP, the response characteristic and the EMI suppression effect of a PFC circuit in practical application are comprehensively considered, the change frequency is designed to be more suitable within the range of 10-100 kHz, and 40kHz is designed in the embodiment; in addition, the capacitance of the capacitor C1 affects the smoothness of the change between the maximum frequency and the minimum frequency in each period, and in principle, the switching frequency is prevented from generating instantaneous jump between the maximum frequency and the minimum frequency, and 100pF is selected in the embodiment.
In the above embodiment, the circuit formed by the resistors R1 and R2, the transistor Q1 and the capacitor C1 may be replaced by other circuits or components capable of controlling impedance change.
In a specific embodiment, as shown in fig. 12, the variable frequency control circuit includes a first resistor R1, a second resistor R2, a multi-channel analog switch chip and a capacitor C1; one end of the first resistor R1 and one end of the second resistor R2 are respectively connected with input ports of a first channel and a second channel of the multichannel analog switch chip, the other end of the first resistor R1 and the other end of the second resistor R2 are connected with a frequency configuration interface of the PFC control chip, a control port of the multichannel analog switch chip is connected with a PWM signal output end of the microcontroller, an output port of the multichannel analog switch chip is grounded, one end of the capacitor C1 is connected with the other end of the first resistor R1, the other end of the capacitor C1 is grounded, and the multichannel analog switch chip controls the input port and the output port of the corresponding channel to be connected according to high-low level signals input by the control port.
Fig. 12 provides another alternative of the present invention, in which U1 is a multi-channel analog switch chip, and the input channel and the output port of the corresponding signal can be controlled to conduct respectively according to the high-low level signal of the chip control port, for example, when the control port is at low level, the first channel conducts with the output port, and when the control port is at high level, the second channel conducts with the output port. In this case, the U1 control port is connected to the PWM port of the MCU, the first channel is connected to the resistor R1, and the second channel is connected to the resistor R2, wherein the resistance value types of the R1 and the R2 respectively correspond to the upper limit value f1 and the lower limit value f2 of the working frequency of the PFC chip, in this embodiment, the upper limit value f1 and the lower limit value f2 are 40kHz and 38kHz, respectively, when the PWM port of the MCU outputs an f frequency switching signal, the switching frequency of the PFC control chip can be periodically changed between the frequency f1 and the frequency f2 according to the f frequency, and finally the PFC chip is indirectly controlled by the PWM output signal of the MCU/DSP to realize the variable switching frequency control. Similarly, the capacitance of the capacitor C1 affects the smoothness of the change between the maximum frequency and the minimum frequency per cycle, which is 100pF in this case.
In one specific embodiment, as shown in fig. 13, the variable frequency control circuit comprises a first resistor R1, a second resistor R2, a relay circuit and a capacitor C1, wherein the relay circuit comprises a relay drive circuit and a relay K1; one end of each of the first resistor R1 and the second resistor R2 is connected to a frequency configuration interface of the PFC control chip, the other end of the second resistor R2 is connected to the first contact of the relay K1, the other end of the first resistor R1 is grounded, the control end of the relay K1 is connected to the output end of the relay drive circuit, the input end of the relay drive circuit is connected to the PWM signal output end of the microcontroller, the second contact of the relay K1 is grounded, the capacitor C1 is connected in parallel to the two ends of the first resistor R1, and the relay controls the connection or disconnection of the first contact and the second contact according to the output signal of the relay drive circuit.
In addition, an embodiment of the present invention further provides a home appliance device, where the home appliance device includes the PFC circuit with variable switching frequency as described above, where a specific implementation scheme of the PFC circuit with variable switching frequency is shown in fig. 11, 12, or 13.
The PFC circuit with the variable switching frequency and the household appliance provided by the embodiment of the invention adopt the PFC control scheme with the variable switching frequency, can avoid the problem that the switching noise interference energy of a power switching tube under a certain fixed frequency in the conventional PFC circuit is concentrated in a fixed frequency section, can disperse the switching noise energy of the power switching tube in a wider frequency range, and can effectively reduce the maximum noise interference value of a product.
Furthermore, when the household appliance with the PFC circuit with the variable switching frequency is used for EMI test, the maximum switching noise interference value is effectively reduced by 8-10 dB compared with the maximum noise interference value of the original fixed frequency scheme, and the product development difficulty and cost are effectively reduced.
Those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than others, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A PFC circuit with variable switching frequency is characterized by comprising a variable frequency control circuit, a PFC switching circuit and a PFC control chip;
the PFC switch circuit is connected with a switch control interface of the PFC control chip and outputs a corresponding PFC switch control signal according to a received control signal, and the PFC switch control signal is used for controlling the PFC control chip to be turned on or turned off;
and the frequency conversion control circuit is connected with a frequency configuration interface of the PFC control chip, and outputs a switching frequency signal with the same period as the PWM signal according to the received PWM signal, wherein the switching frequency signal is used for controlling the working frequency of the PFC control chip.
2. The PFC circuit with variable switching frequency according to claim 1, wherein the variable frequency control circuit comprises a first resistor R1, a second resistor R2, a transistor Q1 and a capacitor C1;
the collector of the transistor Q1 is connected with one end of the second resistor R2, the base of the transistor Q1 is connected with the PWM signal output end of the microcontroller, the emitter of the transistor Q1 is grounded, the other end of the second resistor R2 is connected with the frequency configuration interface of the PFC control chip, one ends of the first resistor R1 and the capacitor C1 are respectively connected with the other end of the second resistor R2, and the other ends of the first resistor R1 and the capacitor C1 are respectively grounded.
3. The PFC circuit with the variable switching frequency according to claim 1, wherein the variable frequency control circuit comprises a first resistor R1, a second resistor R2, a multi-channel analog switch chip and a capacitor C1;
one end of the first resistor R1 and one end of the second resistor R2 are respectively connected with input ports of a first channel and a second channel of the multi-channel analog switch chip, the other end of the first resistor R1 and the other end of the second resistor R2 are connected with a frequency configuration interface of the PFC control chip, a control port of the multi-channel analog switch chip is connected with a PWM signal output end of the microcontroller, an output port of the multi-channel analog switch chip is grounded, one end of the capacitor C1 is connected with the other end of the first resistor R1, the other end of the capacitor C1 is grounded, and the multi-channel analog switch chip respectively controls the input ports of the corresponding channels to be conducted with output ports according to high-low level signals input by the control port.
4. The variable switching frequency PFC circuit of claim 1, wherein the variable frequency control circuit comprises a first resistor R1, a second resistor R2, a relay circuit comprising a relay driver circuit and a relay, and a capacitor C1;
one end of the first resistor R1 and one end of the second resistor R2 are respectively connected with a frequency configuration interface of the PFC control chip, the other end of the second resistor R2 is connected with a first contact of the relay, the other end of the first resistor R1 is grounded, the control end of the relay is connected with the output end of the relay driving circuit, the input end of the relay driving circuit is connected with the PWM signal output end of the microcontroller, the second contact of the relay is grounded, the capacitor C1 is arranged at two ends of the first resistor R1 in parallel, and the relay controls the connection or disconnection of the first contact and the second contact according to the output signal of the relay driving circuit.
5. The variable switching frequency PFC circuit according to any one of claims 2-4, wherein the capacitance of the capacitor C1 is 100 pF.
6. The PFC circuit with variable switching frequency according to claim 1, wherein the frequency variation range of the switching frequency signal is 1-4 kHz.
7. The variable switching frequency PFC circuit of claim 6, wherein the frequency variation range of the switching frequency signal is 2 kHz.
8. The PFC circuit with the variable switching frequency according to claim 1, wherein the switching frequency signal has a value ranging from 10 kHz to 100 kHz.
9. The variable switching frequency PFC circuit of claim 8, wherein an upper limit value of the switching frequency signal is 40kHz and a lower limit value of the switching frequency signal is 38 kHz.
10. A household appliance comprising a variable switching frequency PFC circuit according to any one of claims 1 to 9.
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Cited By (1)
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| CN113489305A (en) * | 2021-05-24 | 2021-10-08 | 杭州洲钜电子科技有限公司 | Nonlinear variable carrier frequency system and method based on PFC harmonic suppression and storage medium |
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| CN104377951A (en) * | 2014-11-12 | 2015-02-25 | 广东美的制冷设备有限公司 | Power factor correction method and device, air conditioner and electric appliance |
| CN105610316A (en) * | 2015-08-14 | 2016-05-25 | 许继电源有限公司 | Frequency jittering circuit |
| WO2019046939A1 (en) * | 2017-09-05 | 2019-03-14 | The Governing Council Of The University Of Toronto | Electric vehicle power-hub and operating modes thereof |
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| CN113489305A (en) * | 2021-05-24 | 2021-10-08 | 杭州洲钜电子科技有限公司 | Nonlinear variable carrier frequency system and method based on PFC harmonic suppression and storage medium |
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Application publication date: 20200317 |