CN112737370B - AC/DC converter - Google Patents

AC/DC converter Download PDF

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Publication number
CN112737370B
CN112737370B CN202110114405.8A CN202110114405A CN112737370B CN 112737370 B CN112737370 B CN 112737370B CN 202110114405 A CN202110114405 A CN 202110114405A CN 112737370 B CN112737370 B CN 112737370B
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Prior art keywords
voltage
auxiliary
main
converter
output
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CN202110114405.8A
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CN112737370A (en
Inventor
胡炎申
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Moso Power Supply Technology Co ltd
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Moso Power Supply Technology Co ltd
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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
    • H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
    • H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
    • H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
    • H02M7/12—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • 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
    • H02M1/14—Arrangements for reducing ripples from DC input or output
    • H02M1/15—Arrangements for reducing ripples from DC input or output using active elements
    • 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
    • H02M1/4208—Arrangements for improving power factor of AC input
    • 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
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/02—Conversion of DC power input into DC power output without intermediate conversion into AC
    • H02M3/04—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters
    • H02M3/10—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • 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

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The present application relates to an AC/DC converter. The AC/DC converter comprises a power factor correction PFC main converter, a DC/DC auxiliary converter, a PFC controller and a DC/DC controller; the PFC main converter comprises a main output end and a direct current output end, wherein the direct current output end is connected with an auxiliary input end of the DC/DC auxiliary converter, and the main output end is connected with an auxiliary output end of the DC/DC auxiliary converter in series to form a total output end; and the control end of the PFC controller is connected with the PFC main converter, and the control end of the DC/DC controller is connected with the DC/DC auxiliary converter. The PFC controller and the DC/DC controller control output voltage ripples of the PFC main converter and the DC/DC auxiliary converter to be in opposite phase, so that the total output end outputs lower ripples, and the conversion efficiency is improved.

Description

AC/DC converter
Technical Field
The application relates to the technical field of circuits, in particular to an alternating current/direct current (ALTERNATING CURRENT TO DIRECT CURRENT, alternating current/direct current) converter.
Background
Switching power supplies are widely used in various consumer electronics and industrial devices, such as chargers, power adapters, LED drivers, industrial control power supplies, and the like.
Currently, a switching power supply mainly comprises a single stage and a multi-stage. Because the single-stage switching power supply has a simple structure and low cost, but cannot simultaneously input high power factor and output low ripple, even the power tube has over-high voltage or current stress, the two-stage cascade structure is generally widely used in the industry. The two-stage switching power supply can realize high power factor and reduce output ripple voltage or current, but the total output can be obtained after the alternating current input is subjected to two-stage full-power conversion, the conversion efficiency is multiplied by the conversion efficiency of the two converters, and more power consumption is inevitably generated, so that the overall conversion efficiency is low.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, an objective of the present application is to provide an AC/DC converter, which is capable of solving the problem that the conversion efficiency is not high and the output ripple is low.
An embodiment of the present application provides an AC/DC converter including: a power factor correction PFC main converter, a DC/DC auxiliary converter, a PFC controller and a DC/DC controller;
the PFC main converter comprises a main output end and a direct current output end, wherein the direct current output end is connected with an auxiliary input end of the DC/DC auxiliary converter, and the main output end is connected with an auxiliary output end of the DC/DC auxiliary converter in series to form a total output end;
The control end of the PFC controller is connected with the PFC main converter; the control end of the DC/DC controller is connected with the DC/DC auxiliary converter;
The PFC main converter outputs main output voltage through the main output end; the PFC main converter outputs a direct current output voltage through the direct current output end and transmits the direct current output voltage to an auxiliary input end of the DC/DC auxiliary converter; the DC/DC auxiliary converter processes the direct current output voltage to obtain auxiliary output voltage, ripple waves of the auxiliary output voltage are opposite to those of the main output voltage, and the auxiliary output voltage is output through the auxiliary output end;
The total output end receives the main output voltage and the auxiliary output voltage to form a total output voltage; the PFC controller samples a first feedback voltage, and controls the input voltage and the input current of the PFC main converter to have the same frequency and the same phase by using the first feedback voltage; the DC/DC controller samples a second feedback voltage, and utilizes the second feedback voltage to control the ripple wave of the auxiliary output voltage output by the auxiliary output end of the DC/DC auxiliary converter to be opposite to the ripple wave phase of the first voltage;
The first feedback voltage comprises one of the main output voltage and the total output voltage, and the second feedback voltage comprises the total output voltage when the first feedback voltage is the main output voltage; in the case where the first feedback voltage is a total output voltage, the second feedback voltage includes one of the main output voltage and the auxiliary output voltage.
In one possible implementation, the PFC main converter further comprises a power conversion unit, a main power switching tube and a voltage conversion unit,
The main power switching tube is connected between the output end of the power conversion unit and the input end of the voltage conversion unit, the control end of the main power switching tube is connected with the control end of the PFC controller, and the output end of the voltage conversion unit is connected with the main output end and the direct current output end;
the PFC controller controls the on and off of the main power switch tube;
when the main power switch tube is conducted, the power conversion unit provides electric energy for the voltage conversion unit, and the voltage conversion unit stores the electric energy;
And under the condition that the main power switching tube is cut off, the power conversion unit stops supplying electric energy to the voltage conversion unit, and the voltage conversion unit releases the electric energy.
In one possible implementation, the voltage conversion unit includes a main winding and an auxiliary winding;
One end of the main winding is connected with one end of the main power switch tube, and the other end of the main winding is connected with the main output end; one end of the auxiliary winding is connected with one end of the main power switch tube, and the other end of the auxiliary winding is connected with the auxiliary output end;
the voltage conversion unit outputs the main output voltage to the main output end through the main winding; the voltage conversion unit outputs the direct-current output voltage to the direct-current output end through the auxiliary winding.
In one possible implementation, the PFC controller includes a first sampling unit and a first conditioning feedback unit;
the output end of the first sampling unit is connected with the input end of the first conditioning feedback unit, and the output unit of the first conditioning feedback unit is connected with the control end of the main power switch tube;
the first sampling unit is used for: sampling the first feedback voltage; the first conditioning feedback unit is used for: generating a first switch drive signal based on the first feedback voltage; the first switch driving signal is used for controlling the on and off of the main power switch tube.
In one possible implementation manner, the first sampling unit includes a first sampling end, a second sampling end and a third sampling end; the first conditioning feedback unit includes: the first comparator, the second comparator, the third comparator, the first reference voltage source, the first sawtooth wave signal source and the trigger;
The output end of the first reference voltage source is connected with the positive input end of the first comparator, and the first sampling end is connected with the negative input end of the first comparator; the output end of the first comparator is connected with the positive input end of the second comparator, and the reverse input end of the second comparator is connected with the second sampling end; the output end of the second comparator is connected with the positive input end of the third comparator, the first sawtooth wave signal source is connected with the reverse input end of the third comparator, the output end of the third comparator is connected with the first input end of the trigger, the third sampling end is connected with the second input end of the trigger, and the output end of the trigger is connected with the control end of the main power switch tube;
the first comparator receives a first feedback voltage from the first sampling end and a reference voltage from the reference voltage source, compares the first feedback voltage with the reference voltage, and forms a first voltage error signal;
the second comparator receives a switching tube voltage signal from the second sampling end and a first voltage error signal from the first comparator, compares the first voltage error signal with the switching tube voltage signal to obtain a control signal of the main power switching tube, and the switching tube voltage signal is obtained by converting a current signal of the main power switching tube;
The third comparator receives a current control signal from the second comparator and a first sawtooth wave signal from the first sawtooth wave signal source, and compares the control signal with the sawtooth wave signal to obtain a stop pulse signal; the third sampling end samples the electric energy of the voltage conversion unit to form a starting pulse signal;
the trigger receives the stop pulse signal and the start pulse signal, generates the first switch driving signal based on the start pulse signal and the stop pulse signal, and the first switch driving signal is used for controlling the on and off of the main power switch tube.
In one possible implementation, the DC/DC auxiliary converter includes an auxiliary power switching tube, an inductor, and a diode;
One end of the auxiliary power switch tube is connected with one pole of an auxiliary input end of the DC/DC auxiliary converter, the other end of the auxiliary power switch tube is connected with one end of the inductor, the other end of the inductor is connected with one pole of an auxiliary output end, one end of the diode is connected between a source electrode of the auxiliary power switch tube and one end of the inductor, and the other end of the diode is connected between the other pole of the auxiliary input end of the DC/DC auxiliary converter and the other pole of the auxiliary output end;
Under the condition that the auxiliary power switch tube is conducted, the diode is cut off, the auxiliary input end of the DC/DC auxiliary converter receives the direct-current output voltage to provide electric energy for the inductor, and the inductor stores the electric energy;
Under the condition that the auxiliary power switch tube is cut off, the diode is conducted, the inductor, the diode and the auxiliary output end form a current loop, the inductor releases electric energy to provide electric energy for the auxiliary output end, and the auxiliary output end outputs the auxiliary output voltage.
In one possible implementation, the DC/DC controller includes a second sampling unit and a second conditioning feedback unit;
The output end of the second sampling unit is connected with the input end of the second conditioning feedback unit, and the output end of the second conditioning feedback unit is connected with the control end of the auxiliary power switch tube;
The second sampling unit is used for: sampling the second feedback voltage; the second conditioning feedback unit is used for: generating a second switch drive signal based on the second feedback voltage; the second switch driving signal is used for controlling the auxiliary power switch tube.
In one possible implementation, the second conditioning feedback unit includes a fourth comparator, a fifth comparator, a second reference voltage source, and a second sawtooth signal source;
the output end of the second reference voltage source is connected with the positive input end of the fourth comparator, and the reverse input end of the fourth comparator is connected with the output end of the second sampling unit; the output end of the fourth comparator is connected with the positive input end of a fifth comparator, the reverse input end of the fifth comparator is connected with the output end of the second sawtooth wave signal source, and the output end of the fifth comparator is connected with the control end of the auxiliary power switch tube;
The fourth comparator is used for comparing the second feedback voltage with the second reference voltage to generate a second voltage error signal; the fifth comparator is used for comparing the second voltage error signal with a second sawtooth wave signal to generate a second switch driving signal, and the second switch driving signal is used for controlling the on and off of the auxiliary power switching tube.
In one possible implementation, the voltage stress of the DC/DC auxiliary converter is smaller than a first threshold value and the current stress of the DC/DC auxiliary converter is smaller than a second threshold value.
In one possible embodiment, the PFC controller includes a first communication unit, and the DC/DC controller includes a second communication unit, the first communication unit establishing a communication connection with the second communication unit.
In one possible implementation manner, the control mode of the PFC controller includes: one of a current critical conduction mode, a current discontinuous conduction mode, and a current continuous conduction mode.
In one possible implementation manner, the PFC main converter includes one of a flyback converter, a boost converter, a buck-boost converter, a cuckoo converter, and a forward converter;
In one possible embodiment, the DC/DC auxiliary converter includes one of a flyback converter, a boost converter, a buck-boost converter, a chucky converter, a forward converter, a bridge converter, a push-pull converter, a single-ended primary inductive converter, and an LLC resonant converter.
In the embodiment of the application, the main output voltage output by the PFC main converter and the auxiliary output voltage output by the DC/DC auxiliary converter form the total output voltage, and only a part of output power is subjected to two-stage conversion, so that the conversion efficiency of the AC/DC converter is improved. The PFC controller samples and feeds back the main output voltage or the total output voltage, and controls the input current and the input voltage of the PFC main converter to be the same-frequency and same-phase sine wave while realizing the closed-loop control of the main output voltage or the total output voltage so as to achieve the power factor correction and higher power factor and realize zero pollution to a power grid. The DC/DC controller samples and feeds back the second feedback voltage, and the second feedback voltage is closed-loop controlled according to the change condition of the second feedback voltage, so that the lower ripple of the total output voltage is realized by indirectly controlling the opposite-phase superposition of the ripple output by the main output voltage and the auxiliary output voltage to be mutually offset while the closed-loop control of the second feedback voltage is realized.
Drawings
Fig. 1 is a schematic structural diagram of an AC/DC converter according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of another AC/DC converter according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of another AC/DC converter according to an embodiment of the present application;
fig. 4 is a schematic structural diagram of another AC/DC converter according to an embodiment of the present application;
fig. 5 is a schematic structural diagram of a buck PFC main converter according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of a boost PFC main converter according to an embodiment of the present application;
fig. 7 is a schematic structural diagram of a buck-boost PFC main converter according to an embodiment of the present application;
fig. 8 is a schematic structural diagram of a boost DC/DC auxiliary converter according to an embodiment of the present application;
Fig. 9 is a schematic structural diagram of a buck-boost DC/DC auxiliary converter according to an embodiment of the present application;
fig. 10 is a schematic structural diagram of a negative voltage step-down DC/DC auxiliary converter according to an embodiment of the present application;
fig. 11 is a schematic structural diagram of a flyback DC/DC auxiliary converter according to an embodiment of the present application.
Reference numerals illustrate:
PFC main converter 10, power conversion unit 11, voltage conversion unit 12, main winding 121, auxiliary winding 122, DC/DC auxiliary converter 20, PFC controller 30, DC/DC controller 40, ac power supply 50, load 60, PFC main converter input ports 1, 2, main outputs 3, 4, DC outputs 5, 6, auxiliary outputs 7, 8.
Detailed Description
In order that the application may be readily understood, a more complete description of the application will be rendered by reference to the appended drawings. The drawings illustrate preferred embodiments of the application. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
The terms first, second and the like in the description and in the claims and in the above-described figures are used for distinguishing between different objects and not necessarily for describing a sequential or chronological order. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application.
Referring to fig. 1, fig. 1 is a schematic structural diagram of an AC/DC converter according to an embodiment of the application. As shown in fig. 1, the AC/DC converter includes a power factor correction (Power Factor Correction, PFC) main converter 10, a direct current/direct current (direct current to direct current, DC/DC) auxiliary converter 20, a PFC controller 30, and a DC/DC controller 40.
The PFC main converter 10 includes a main output terminal and a DC output terminal, the DC output terminal is connected to an auxiliary input terminal of the DC/DC auxiliary converter 20, and the main output terminal is connected in series with an auxiliary output terminal of the DC/DC auxiliary converter 20 to form a total output terminal.
A control terminal of the PFC controller 30 is connected to the PFC main converter 10, and a control terminal of the DC/DC controller 40 is connected to the DC/DC sub converter 20.
The PFC main converter 10 outputs a main output voltage Vo1 through the main output terminal. The PFC main converter 10 outputs a DC output voltage Vo3 through the DC output terminal, and transmits the DC output voltage Vo3 to an auxiliary input terminal of the DC/DC auxiliary converter 20. The DC/DC auxiliary converter 20 processes the DC output voltage Vo3 to obtain an auxiliary output voltage Vo2, and the auxiliary output voltage Vo2 is output through the auxiliary output terminal, wherein a ripple of the auxiliary output voltage Vo2 is opposite in phase to a ripple of the main output voltage Vo1.
The total output end receives the main output voltage Vo1 and the auxiliary output voltage Vo2 to form a total output voltage Vo. The PFC controller 30 samples a first feedback voltage, and controls the input voltage and the input current of the PFC main converter 10 to have the same frequency and the same phase by using the first feedback voltage. The DC/DC controller 40 samples a second feedback voltage Vo2s, and controls the ripple of the auxiliary output voltage Vo2 outputted from the auxiliary output terminal of the DC/DC auxiliary converter 20 to be opposite to the ripple of the main output voltage Vo1 by using the second feedback voltage.
The first feedback voltage includes one of the main output voltage Vo1 and the total output voltage Vo, and the second feedback voltage includes the total output voltage Vo when the first feedback voltage Vo1s is the main output voltage Vo 1. In the case where the first feedback voltage is the total output voltage Vo, the second feedback voltage includes one of the main output voltage Vo1 and the auxiliary output voltage Vo 2.
Specifically, an input terminal of the PFC main converter 10 is connected to an output terminal of an ac power supply 50, and the ac power supply 50 supplies ac power to the PFC main converter 10. After the PFC main converter 10 performs power conversion and voltage conversion on the ac power, a main output voltage Vo1 is output through a main output terminal and a DC voltage Vo3 is output through a DC output terminal, and the main output voltage Vo1 is transmitted to a main output terminal, and the DC output voltage Vo3 is output to an auxiliary input terminal of the DC/DC auxiliary converter 20. After receiving the DC output voltage Vo3, the DC/DC auxiliary converter 20 converts the DC output voltage Vo3 to obtain an auxiliary output voltage Vo2, and transmits the auxiliary output voltage Vo2 to the total output terminal through an auxiliary output terminal of the DC/DC auxiliary converter 20. The total output end receives the main output voltage Vo1 and the auxiliary output voltage Vo2 to form a total output voltage Vo for charging the load 60.
A control terminal of the PFC controller 30 is connected to the PFC main converter 10, and an input terminal of the PFC controller 30 may be connected to a main output terminal or a total output terminal to sample a first feedback voltage, the PFC main converter 10 being controlled based on the first feedback voltage, the PFC main converter 10 and the PFC controller 30 forming a first feedback loop. The control terminal of the DC/DC controller 40 is connected to the DC/DC auxiliary converter 20, and the input terminal of the DC/DC controller 40 may be connected to the main output terminal, the auxiliary output terminal, or the total output terminal to sample a second feedback voltage, based on which the DC/DC auxiliary converter 20 is controlled, and the DC/DC auxiliary converter 20 and the DC/DC controller 40 form a second feedback loop.
It will be appreciated that the total output is formed by the primary and secondary outputs in series, so that the total output voltage Vo is the sum of the primary and secondary output voltages Vo1 and Vo 2. Since the power frequency ripple is an inherent characteristic of the main output voltage Vo1 and the auxiliary output voltage Vo2, the power frequency ripple of the auxiliary output voltage Vo2 outputted by the DC/DC controller 40 is controlled to be opposite to the power frequency ripple of the main output voltage Vo1, so that the power frequency ripple of the main output voltage Vo1 and the power frequency ripple of the auxiliary output voltage Vo2 are offset after being overlapped, and the total output voltage Vo has lower ripple.
In the case that the first feedback voltage is the main output voltage, the PFC controller 30 samples and feeds back the main output voltage Vo1, and controls the PFC main converter 10 based on the sampled main output voltage Vo1, and controls the input voltage of the PFC main converter 10 to be identical in frequency and phase to the input current to achieve a power factor dumpling and a higher power factor while realizing closed-loop control of the main output voltage Vo 1. The DC/DC controller 40 samples and feeds back the total output voltage Vo, controls the total output voltage Vo according to a variation condition of the total output voltage Vo such that the total output voltage Vo is a stable voltage, thereby indirectly controlling output ripple of the main output voltage Vo1 and output ripple of the auxiliary output voltage Vo2 to be inverted. The second feedback loop indirectly controls the ripple waves output by the main output voltage Vo1 and the auxiliary output voltage Vo2 to be in reverse superposition and offset each other, so that lower ripple waves of the total output voltage Vo are realized.
In the case that the first feedback voltage is the total output voltage, the PFC controller 30 samples and feeds back the total output voltage Vo, controls the total output voltage Vo according to the conversion of the total output voltage Vo, so that the total output voltage Vo is a stable voltage, and controls the input current and the input voltage of the PFC main converter 10 to be sine waves with the same frequency and the same phase while realizing the closed loop control of Vo, so as to achieve the power factor correction and higher power factor, and realize zero pollution to the power grid. The DC/DC controller 40 samples and feeds back the main output voltage Vo1 or the auxiliary output voltage Vo2, controls the total main output voltage Vo1 or the auxiliary output voltage Vo2 according to a variation condition of the main output voltage Vo1 or the auxiliary output voltage Vo2, and realizes lower ripple of the total output voltage Vo by indirectly controlling the inverse superposition of ripple output by the main output voltage Vo1 and the auxiliary output voltage Vo2 to cancel each other.
In the embodiment of the present application, the main output voltage Vo1 is greater than the auxiliary output voltage Vo2, the PFC main converter 10 provides most of the power for the load 60, the DC/DC auxiliary converter 20 provides a small portion of the output power for the load 60, the large portion of the output power is subjected to single-stage power conversion, and only the small portion of the output power is subjected to two-stage power conversion, so that the overall power conversion efficiency is improved.
Specifically, assuming that the conversion efficiency of the PFC main converter 10 is η PFC and the conversion efficiency of the DC/DC auxiliary converter 20 is η DC/DC,PPFC、PDC/DC、Pout, which are the PFC main converter 10 output power, the DC/DC auxiliary converter 20 output power, and the overall output power, respectively, the overall efficiency is:
let P DC/DC＝10％×Pout be:
Let η DC/DC =90%, the overall conversion efficiency η total＝98.9％×ηPFC.
From the above, if the output power of the DC/DC auxiliary converter 20 is 10%, even if the conversion efficiency of the DC/DC auxiliary converter 20 is as low as 90%, the overall conversion efficiency is close to 99% of that of the single-stage converter, with lower power loss and higher conversion efficiency than the conventional two-stage converter.
In one possible implementation, referring to fig. 2, fig. 2 is a schematic structural diagram of another AC/DC converter according to an embodiment of the present application. As shown in fig. 2, the PFC main converter 10 further includes a power conversion unit 11, a main power switching tube Q1, and a voltage conversion unit 12.
The main power switching tube Q1 is connected between the power conversion unit 11 and the voltage conversion unit 12, the control end of the main power switching tube Q1 is connected with the control end of the PFC controller 30, and the output end of the voltage conversion unit 12 is connected with the main output end and the direct current output end.
Specifically, the PFC controller 30 samples the main output voltage Vo1 or the total output voltage Vo to constitute a first feedback signal. The PFC controller 30 generates a first switching tube driving signal based on the first feedback signal, and transmits the generated first switching tube driving signal to a control terminal of the main power switching tube Q1 through a control terminal of the PFC controller 30 to control on and off of the main power switching tube Q1.
When the main power switching transistor Q1 is turned on, the power conversion unit 11 receives ac power from an ac power source, converts the ac power, and supplies power to the voltage conversion unit 12, and the voltage conversion unit 12 stores the power.
When the main power switching transistor Q1 is turned off, the connection between the power conversion unit 11 and the voltage conversion unit 12 is disconnected, the power conversion unit 11 stops supplying the voltage conversion unit 12 with electric power, and the voltage conversion unit 12 discharges the electric power.
In the embodiment of the application, the PFC controller 30 controls the on and off of the main power switching tube Q1 to realize the closed loop control of the main output voltage Vo1 or the total output voltage Vo, and meanwhile, the envelope waveform of the input current is changed along with the power frequency sine wave of the input voltage to become intermittent, critical or continuous high-frequency changed current by a conventional control mode such as a current intermittent conduction mode (Discontinuous Conduction Mode, DCM), a current critical conduction mode (Critical Conduction Mode, CRM) or a current continuous conduction mode (Continuous Conduction Mode, CCM) with a multiplier, so as to eliminate the distortion of the current waveform and the change of the phase caused by the energy storage of the capacitive element and the inductive element in the conventional circuit without the power factor correction function, and the input current is the same as the input voltage frequency and the phase after being filtered by the input electromagnetic interference (Electromagnetic Interference, EMI) filter, thereby realizing the power factor correction and the power factor improvement.
In one possible implementation, referring to fig. 2, the voltage conversion unit 12 includes a main winding 121 and an auxiliary winding 122.
One end of the main winding 121 is connected to one end of the main power switching tube Q1, and the other end of the main winding 121 is connected to the main output terminal. One end of the auxiliary winding 122 is connected to one end of the main power switching tube Q1, and the other end of the auxiliary winding 122 is connected to the auxiliary output terminal.
The voltage conversion unit 12 outputs the main output voltage Vo1 to the main output terminal through the main winding 121. The voltage conversion unit 12 outputs the dc output voltage Vo3 to the dc output terminal through the auxiliary winding 122.
The voltage converting unit 12 may be a double winding type transformer or a double winding inductance L1 having a main winding 121 and an auxiliary winding 122.
The resistance of the main winding 121 is smaller than that of the auxiliary winding 122, so that the voltage of the main winding 121 is greater than that of the auxiliary winding 122 under the condition of the same current, that is, the main output voltage Vo1 is greater than the auxiliary output voltage Vo2, and the output power of the main output terminal is greater than that of the auxiliary output terminal. Thereby, the conversion efficiency can be improved better.
In one possible implementation, referring to fig. 3, pfc controller 30 includes a first sampling unit 31 and a first conditioning feedback unit 32.
The output end of the first sampling unit 31 is connected with the input end of the first conditioning feedback unit 32, and the output unit of the first conditioning feedback unit 32 is connected with the control end of the main power switch tube Q1. The first sampling unit 31 is configured to: and sampling the first feedback voltage. The first conditioning feedback unit 32 is configured to: a first switch drive signal is generated based on the first feedback voltage. The first switch driving signal is used for controlling the on and off of the main power switch tube Q1.
Specifically, the first feedback voltage may include one of a main output voltage Vo1 and a total output voltage Vo, and an input terminal of the first sampling unit 31 may be connected to the main output terminal or the total output terminal to sample the first feedback voltage and then transmit the first sampled voltage to the first conditioning feedback unit 32. The first conditioning feedback unit 32 generates a first switch driving signal based on the first feedback voltage, and transmits the first switch driving signal to the control terminal of the main power switching tube Q1 to control the on and off of the main power switching tube Q1. The first sampling unit 31, the first conditioning feedback unit 32, the main power switching tube Q1, the voltage conversion unit 12 and the main output end or the total output end form a first feedback loop, and the total output voltage Vo is indirectly controlled through the first feedback loop so as to realize closed loop control of the main output voltage Vo1 or the total output voltage Vo.
In the embodiment of the application, the PFC controller 30 controls the on and off of the main power switching tube Q1 to realize the closed-loop control of the main output voltage or the total output voltage, and simultaneously controls the input current and the output current to be sine waves with the same frequency and the same phase so as to achieve the power factor correction and higher power factor.
In one possible embodiment, referring to fig. 4, the first sampling unit 31 includes a first sampling end a1, a second sampling end a2, and a third sampling end a3. The first conditioning feedback unit 32 includes: the first comparator U1, the second comparator U2, the third comparator U3, the first reference voltage source Vr1, the first sawtooth wave signal source Vramp1 and the trigger U4.
The output terminal of the first reference voltage source Vr1 is connected to the positive input terminal of the first comparator U1, and the first sampling terminal a1 is connected to the negative input terminal of the first comparator U1. The output end of the first comparator U1 is connected to the positive input end of the second comparator U2, and the negative input end of the second comparator U2 is connected to the second sampling end a 2. The output end of the second comparator U2 is connected to the positive input end of the third comparator U3, the first saw-tooth wave signal source Vramp1 is connected to the negative input end of the third comparator U3, the output end of the third comparator U3 is connected to the first input end of the trigger U4, the third sampling end a3 is connected to the second input end of the trigger U4, and the output end of the trigger U4 is connected to the control end of the main power switching tube Q1.
The first comparator U1 receives the first feedback voltage from the first sampling terminal a1 and the reference voltage from the first reference voltage source Vr1, and compares the first feedback voltage with the reference voltage to form a first voltage error signal.
The second comparator U2 receives the switching tube voltage signal from the second sampling end a2 and the first voltage error signal from the first comparator U1, compares the first voltage error signal with the switching tube voltage signal, and obtains a current control signal of the main power switching tube Q1, where the switching tube voltage signal is obtained by converting a current signal of the main power switching tube Q1.
The third comparator U3 receives the current control signal from the second comparator U2 and the first sawtooth wave signal from the first sawtooth wave signal source Vramp1, and compares the current control signal with the sawtooth wave signal to obtain a stop pulse signal. The third sampling terminal a3 samples the energy release signal of the voltage conversion unit 12 to form a start pulse signal.
The flip-flop U4 receives the stop pulse signal and the start pulse signal, and generates the first switch driving signal for controlling the on and off of the main power switching tube Q1 based on the start pulse signal and the stop pulse signal.
Specifically, the first sampling end a1 may be directly connected to the main output end or the total output end to sample the main output voltage Vo1 or the total output voltage Vo to form a first feedback voltage. The second sampling end a2 can detect the current of the main power switching tube Q1 through a resistor Ri and convert the current into a voltage signal to form a switching tube voltage signal. The third sampling terminal a3 may detect the energy release signal of the voltage conversion unit 12 through the resistor Redm to form a start pulse signal. The first sampling terminal a1 transmits the sampled first feedback voltage to the inverting input terminal of the first comparator U1. The positive input of the first comparator U1 is connected to a first reference voltage source Vr1, the first reference voltage source Vr1 transmitting a first voltage reference to the positive input of the first comparator U1. The first comparator U1 compares the first feedback voltage with the first voltage reference to obtain a voltage error signal, and amplifies the voltage error signal and outputs the amplified voltage error signal to the positive input end of the second comparator U2. The second sampling terminal a2 transmits the switching tube voltage signal to the inverting input terminal of the second comparator U2 to control the peak current of the main power switching tube Q1. The second comparator U2 compares the first voltage error signal with the switching tube voltage signal to form a control signal of the main power switching tube Q1, and transmits the control signal to the positive input terminal of the third comparator U3. The third comparator receives the standard sawtooth signal from the first sawtooth signal source Vramp1, compares the standard sawtooth signal with the control signal to form a stop pulse signal, and transmits the stop pulse signal to the first input end of the trigger U4. The third sampling terminal a1 transmits a start pulse signal to the second input terminal of the flip-flop U4. The trigger U4 generates a switch driving signal based on the start pulse signal and the stop pulse signal, and transmits the generated switch driving signal to the control terminal of the main power switching tube Q1 to control the on or off of the main power switching tube Q1. The switch driving signal may be a pulse width modulation (pulse width modulation, PWM) switch driving signal, and the flip-flop may be a Reset-Set (RS) flip-flop.
In the embodiment of the present application, the voltage of the reference voltage is constant, and the PFC controller 30 controls the sampled main output voltage Vo1 or the total output voltage Vo to be equal to the reference voltage in real time through sampling, conditioning and feedback, thereby implementing closed loop control of the main output voltage Vo1 or the total output voltage Vo. By using the PFC controller 30 with the above structure, the PFC main converter 10 can be precisely controlled, and the PFC main converter is simple in manufacture, low in cost and high in control precision.
In one possible embodiment, the control modes of the PFC controller 30 include: one of a current critical conduction mode, a current discontinuous conduction mode, and a current continuous conduction mode.
In the current critical conduction mode, the PFC controller 30 detects the energy release signal of the voltage converting unit 12 through the third sampling terminal a 3. After the end of one on period of the main power switch Q1, the energy of the voltage converting unit 12 is completely released before the next on period, and the secondary side current of the auxiliary winding 122 decays to zero. The turn-on frequency of the main power switching tube Q1 varies with the line voltage and the load 60.
In the current interruption conduction mode, the PFC controller 30 does not need to detect the energy release signal of the voltage converting unit 12, and the conduction frequency of the main power switching tube Q1 varies with the magnitude of the input voltage. In the current continuous conduction mode, the conduction frequency of the main power switching tube Q1 is fixed, and the duty ratio of conduction changes along with the change of the magnitude of the input voltage.
In the embodiment of the application, different control modes can be selected according to actual needs, and the power factor correction circuit can be adapted to different circuit structures so as to realize power factor correction in each circuit.
In one possible implementation, referring to fig. 4, the DC/DC auxiliary converter 20 includes an auxiliary power switching tube Q2, an inductor L2, and a diode D7.
One end of the auxiliary power switching tube Q2 is connected to one pole of the auxiliary input terminal of the DC/DC auxiliary converter 20, the other end of the auxiliary power switching tube Q2 is connected to one end of the inductor, the other end of the inductor L2 is connected to the port 7 of the auxiliary output terminal, one end of the diode is connected between the other end of the auxiliary power switching tube Q2 and one end of the inductor, and the other end of the diode is connected between the other pole of the auxiliary input terminal of the DC/DC auxiliary converter 20 and the port 8 of the auxiliary output terminal.
When the auxiliary power switching transistor Q2 is turned on, the diode D7 is turned off, the auxiliary input terminal of the DC/DC auxiliary converter 20 receives the DC output voltage, and supplies the electric energy to the inductor L2, and the inductor L2 stores the electric energy.
When the auxiliary power switch Q2 is turned off, the diode D7 is turned on, the inductor L2 and the diode D7 form a current loop with the auxiliary output terminal, and the inductor L2 discharges electric energy to supply electric energy to the auxiliary output terminal, so that the auxiliary output terminal outputs an auxiliary output voltage Vo2.
Specifically, under the condition that the auxiliary power output switching tube Q2 is turned on, the diode D7 is turned off, and the auxiliary input end of the DC/DC auxiliary converter 20 is connected with the inductor L2, so as to provide electric energy for the inductor L2, and the inductor L2 stores the electric energy and outputs the electric energy to the auxiliary output end, so that the auxiliary output end outputs the auxiliary output voltage Vo2. When the auxiliary power switch Q2 is turned off, the diode D7 is turned on, and the inductor L2, the auxiliary input terminal, and the diode D7 form a current loop. The inductor L2 releases electric energy to provide electric energy for the auxiliary output end, so that the auxiliary output end outputs auxiliary output voltage.
In the embodiment of the application, the control of the auxiliary output voltage can be realized by controlling the on and off of the auxiliary power switch tube, and the manufacturing is simple and the cost is low.
In one possible embodiment, referring to fig. 3 and 4, the DC/DC controller 40 includes a second sampling unit 41 and a second conditioning feedback unit 42.
An output end of the second sampling unit 41 is connected to an input end of the second conditioning feedback unit 42, and an output end of the second conditioning feedback unit 42 is connected to a control end of the auxiliary power switching tube Q2.
The second sampling unit 41 is configured to: and sampling the second feedback voltage. The second conditioning feedback unit 42 is configured to: and generating a second switch driving signal based on the second feedback voltage. The second switch driving signal is used for controlling the auxiliary power switch tube Q2.
Specifically, the input terminal of the second sampling unit 41 may be connected to the main output terminal, the auxiliary output terminal, or the total output terminal. The second feedback voltage is the total output voltage in the case that the first feedback voltage is the main output voltage, and may be the main output voltage or the auxiliary output voltage in the case that the first feedback voltage is the total output voltage. The second sampling unit 41 transmits the sampled second feedback voltage to the second conditioning feedback unit 42, and the second conditioning feedback unit 42 generates a second switch driving signal based on the second feedback voltage and transmits the second switch driving signal to the control end of the auxiliary power switching tube Q2 to control the on and off of the auxiliary power switching tube Q2.
In the embodiment of the present application, the second sampling unit 41, the second conditioning feedback unit 42, the auxiliary power switching tube Q2 and the main output end or the total output end form a second feedback loop, and the DC/DC controller generates a second switch driving signal based on the second feedback voltage by sampling the second feedback voltage, and controls the on and off of the auxiliary power switching tube Q2 by using the switch driving signal. The secondary output voltage Vo2, the main output voltage Vo1 or the total output voltage Vo is indirectly controlled through the second feedback loop, so that closed-loop control of the secondary output voltage Vo2, the main output voltage Vo1 or the total output voltage Vo is realized.
In one possible embodiment, referring to fig. 4, the second conditioning feedback unit 42 includes a fourth comparator U5, a fifth comparator U6, a second reference voltage source Vr2, and a second saw-tooth wave signal source Vramp2.
An output terminal of the second reference voltage source Vr2 is connected to a positive input terminal of the fourth comparator U5, and a negative input terminal of the fourth comparator U5 is connected to an output terminal of the second sampling unit 41. The output end of the fourth comparator U5 is connected to the positive input end of the fifth comparator U6, the negative input end of the fifth comparator U6 is connected to the output end of the second saw-tooth wave signal source Vramp2, and the output end of the fifth comparator U6 is connected to the control end of the auxiliary power switching tube Q2.
The fourth comparator U5 is configured to compare the second feedback voltage with the second reference voltage to generate a second voltage error signal. The fifth comparator U6 is configured to compare the second voltage error signal with a second sawtooth signal to generate a second switch driving signal, where the second switch driving signal is configured to control on and off of the auxiliary power switching transistor Q2.
Specifically, the second sampling unit 41 samples a second feedback voltage, which may include one of the main output voltage Vo1, the total output voltage Vo, and the auxiliary output voltage Vo2, and transmits it to the fourth comparator U5. The second reference voltage source Vr2 transmits the second reference voltage to the fourth comparator U5, and the fourth comparator U5 compares the second feedback voltage with the second reference voltage to obtain a second voltage error signal, and amplifies the second voltage error signal and outputs the amplified second voltage error signal to the positive input end of the fifth comparator U6. The second sawtooth signal source Vramp2 transmits a standard sawtooth signal to the inverting input of the fifth comparator U6. The fifth comparator U6 compares the second voltage error signal with the standard sawtooth wave signal to form a second switch driving signal, and transmits the second switch driving signal to the control end of the auxiliary power switch tube Q2 so as to control the on and off of the auxiliary power switch tube Q2.
In the embodiment of the present application, the DC/DC controller 40 is a fast loop control, the frequency of the output second switch driving signal is greater than the frequency of the first switch driving signal, and the DC/DC auxiliary converter 20 rapidly responds to the switch driving signal to control the second feedback voltage to be equal to the second reference voltage in real time. The frequency of the second switch drive signal may be controlled by a sawtooth signal source Vramp 2. The DC/DC controller 40 having the above-described structure is used to control the DC/DC auxiliary converter 20 to precisely control the main output voltage Vo1, the total output voltage Vo, and the auxiliary output voltage Vo2, thereby realizing closed-loop control of the main output voltage Vo1, the total output voltage Vo, and the auxiliary output voltage Vo 2.
In one possible embodiment, the voltage stress of the DC/DC auxiliary converter 20 is smaller than a first threshold value, and the current stress of the DC/DC auxiliary converter 20 is smaller than a second threshold value.
Specifically, the main output voltage Vo1 is greater than the auxiliary output voltage Vo2, the PFC main converter 10 provides a majority of the output power for the load 60, and the DC/DC auxiliary converter 20 provides a minority of the output power for the load 60. Therefore, the power device voltage stress and the current stress in the DC/DC sub-converter 20 are smaller, thereby reducing the component cost.
In one possible embodiment, the PFC main converter includes one of a flyback converter, a boost converter, a buck-boost converter, a cuckoo converter, and a forward converter.
Referring to fig. 4, the pfc main converter 10 includes a power conversion unit 11, a rectifying diode D5, a rectifying diode Db, a voltage conversion unit 12, and a main power switching tube Q1. The several cells may constitute a PFC main converter 10 of the isolated or non-isolated type, such as a buck converter, a boost converter, and a buck-boost converter. The main power switch Q1 also has a body diode D Q1. The PFC main converter 10 has its input terminals including port 1 and port 2, its main output terminal including port 3 and port 4, and its dc output terminal including port 5 and port 6.
The power conversion unit 11 may include an LC filter circuit including a capacitor Cf and an inductor Lf, a diode full-bridge rectifying circuit including a diode D1, a diode D2, a diode D3, and a diode D4, and a filter capacitor Cin.
One end of the inductor Lf is connected with the port 1 of the input end of the PFC main converter 10, the other pole of the inductor Lf is connected with one end of the capacitor Cf, the other end of the capacitor Cf is connected with the port 2 of the input end of the PFC main converter 10, and the two ends of the capacitor Cf form the output end of the LC filter circuit. The negative electrode of D1 is connected with the negative electrode of D2, the positive electrode of D2 is connected with the negative electrode of D4, the positive electrode of D4 is connected with the positive electrode of D3, and the negative electrode of D3 is connected with the positive electrode of D1. One pole of the output end of the LC filter circuit is connected between the positive pole of D1 and the negative pole of D3, the other pole of the output end of the LC filter circuit is connected between the positive pole of D2 and the negative pole of D4, one end of the filter capacitor Cin is connected between the negative pole of D1 and the negative pole of D2, and the other end of the filter capacitor Cin is connected between the positive pole of D3 and the positive pole of D4. Both ends of the filtered voltage Cin constitute output terminals of the power conversion unit 11.
Referring to fig. 4, the following details of the circuit configuration of the flyback-type PFC main converter 10 are as follows:
The voltage conversion unit 12 includes a double-winding transformer T1, one end of the primary side of the primary winding 121 of the T1 is connected to one end of the primary power switching tube Q1, the other end of the primary side of the primary winding 121 of the T1 is connected to one end of the output end of the power conversion unit 11, and the other end of the primary power switching tube Q1 is connected to the other end of the output end of the power conversion unit 11. One end of the secondary side of the main winding 121 of T1 is connected with one end of a diode D5, the other end of the D5 is connected with a port 3, and the other end of the secondary side of the main winding 121 of T1 is connected with a port 4. One end of the secondary side of the T1 auxiliary winding 122 is connected with one end of a diode Db, the other end of the Db is connected with the port 5, and the other end of the secondary side of the T1 auxiliary winding 122 is connected with the port 6.
Referring to fig. 5, the following details of the configuration of a buck converter type PFC main converter 10 are provided:
The voltage conversion unit 12 includes a double winding inductance L1, and the inductance L1 includes a main winding 121 and an auxiliary winding 122. One end of the main power switching tube Q1 is connected with one port of the output end of the power conversion unit 11, the other end of the main power switching tube Q1 is connected with one end of the L1 main winding 121, the control end of the main power switching tube Q1 is connected with the output end of the PFC controller 30, and the other end of the L1 main winding 121 is connected with the port 3 of the main output end. One end of the rectifying diode D5 is connected between one end of the power switching tube and one end of the main winding 121, and the other end of the rectifying diode D5 is connected with the other port of the output end of the power conversion unit 11 and with the port 4 of the main output end. The rectifier diode Db is connected between one end of the auxiliary winding 122 and the port 5 of the dc output terminal, and the other end of the auxiliary winding 122 is connected to the port 6 of the dc output terminal.
Referring to fig. 6, the following details of the construction of a boost converter type PFC main converter 10 are provided:
The voltage conversion unit 12 includes a double winding inductance L1, and the inductance L1 includes a main winding 121 and an auxiliary winding 122. One end of the main winding 121 is connected with one port of the output end of the power conversion unit 11, the other end of the main winding 121 is connected with one end of the main power switching tube Q1, the other end of the main power switching tube Q1 is connected with the other port of the output end of the power conversion unit 11, and the other end of the main power switching tube Q1 is also connected with the port 4 of the main output end. One end of the rectifying diode D5 is connected between the other end of the main winding 121 and one end of the main power switching tube Q1, and the other end of the rectifying diode D5 is connected to the port 3 of the main output terminal. The rectifier diode Db is connected between one end of the auxiliary winding 122 and the port 5 of the dc output terminal, and the other end of the auxiliary winding 122 is connected to the port 6 of the dc output terminal.
Referring to fig. 7, the following details of the structure of a buck-boost converter type PFC main converter 10 are provided:
The voltage converting unit 12 includes a double winding inductance L1, and the double winding inductance L1 includes a main winding 121 and an auxiliary winding 122. One end of the main power switch tube Q1 is connected with one port of the output end of the power conversion unit 11, and the other end of the main power switch tube Q1 is connected with the port 4 of the main output end. One end of the main winding 121 is connected between the other end of the main power switch tube Q1 and the port 4, the other end of the main winding 121 is connected with the other port of the output end of the power conversion unit 11, one end of the rectifying diode D5 is connected between the other end of the main winding 121 and the other port of the output end of the power conversion unit 11, and the other end of the rectifying diode D5 is connected with the port 3 of the main output end. The rectifier diode Db is connected between one end of the auxiliary winding 122 and the port 5 of the dc output terminal, and the other end of the auxiliary winding 122 is connected to the port 6 of the dc output terminal.
In one possible implementation, the DC/DC auxiliary converter 20 includes one of a flyback converter, a boost converter, a buck-boost converter, a chucky converter, a forward converter, a bridge converter, a push-pull converter, a single-ended primary inductive converter, and an LLC resonant converter.
The DC/DC auxiliary converter 20 includes an auxiliary power switching tube Q2, an inductor L2 (or transformer T2), and a rectifying diode D7. The auxiliary power switching tube Q2, the inductor L2 and the rectifying diode D7 may constitute an isolated or non-isolated type DC/DC auxiliary converter 20 such as a buck converter, a boost converter and a buck-boost converter. The auxiliary power switch Q2 also has a body diode D Q2. The auxiliary output end of the DC/DC auxiliary converter 20 comprises a port 7 and a port 8, and the auxiliary input end of the DC/DC auxiliary converter 20 is connected with the ports 5 and 6 of the direct current output end.
Referring to fig. 4, the following details of the configuration of the buck-type DC/DC auxiliary converter 20 are provided:
The DC/DC auxiliary converter 20 includes an auxiliary power switching tube Q2, an inductor L2, and a rectifying diode D7. One end of the auxiliary power switch tube Q2 is connected with the port 5 of the direct current output end, the other end of the auxiliary power switch tube Q2 is connected with one end of the inductor L2, and the other end of the inductor L2 is connected with the port 7 of the auxiliary output end. One end of a rectifying diode D7 is connected between the other end of the auxiliary power switch tube Q2 and one end of the inductor L2, and the other end of the rectifying diode D7 is simultaneously connected with a port 6 of the direct current output end and a port 8 of the auxiliary output end.
Referring to fig. 8, the following details of the construction of a boost converter type DC/DC auxiliary converter 20 are provided:
The DC/DC auxiliary converter 20 includes an auxiliary power switching tube Q2, an inductor L2, and a rectifying diode D7. One end of the inductor L2 is connected to the port 5 of the dc output terminal, and the other end is connected to one end of the rectifier diode D7. The other end of the rectifying diode D7 is connected with the port 7 of the auxiliary output end. One end of the auxiliary power switch tube Q2 is connected between the port 6 of the direct current output end and the port 8 of the auxiliary output end, and the other end of the auxiliary power switch tube Q2 is connected between the other end of the inductor L2 and one end of the rectifier diode D7.
Referring to fig. 9, the following details of the configuration of the buck-boost converter type DC/DC auxiliary converter 20 are given:
The DC/DC auxiliary converter 20 includes an auxiliary power switching tube Q2, an inductor L2, and a rectifying diode D7. One end of the auxiliary power switch tube Q2 is connected with the port 5 of the direct current output end, and the other end is connected with the port 8 of the auxiliary output end. The rectifier diode D7 is connected between the port 6 of the dc output and the port 7 of the auxiliary output. One end of the inductor L2 is connected between the other end of the auxiliary power switch tube Q2 and the port 8 of the auxiliary output end, and the other end of the inductor L2 is connected between the port 6 and the rectifier diode D7.
Referring to fig. 10, the following details of the configuration of the DC/DC auxiliary converter 20 of the negative voltage buck converter type are given:
The DC/DC auxiliary converter 20 includes an auxiliary power switching tube Q2, an inductor L2, and a rectifying diode D7. One end of the auxiliary power switch tube Q2 is connected with one end of the inductor L2, and the other end of the auxiliary power switch tube Q2 is connected with a port 5 of the direct current output end. The other end of the inductor L2 is connected to the port 7 of the auxiliary output. One end of the rectifying diode D7 is connected between the port 6 of the direct current output end and the port 8 of the auxiliary output end, and the other end of the rectifying diode D is connected between one end of the auxiliary power switch tube Q2 and one end of the inductor L2.
Referring to fig. 11, the following details of the structure of the flyback-type DC/DC auxiliary converter 20 are shown:
The DC/DC auxiliary converter 20 includes an auxiliary power switching tube Q2, a transformer T2, and a rectifying diode D7. The transformer T2 comprises a first winding and a second winding, wherein one end of the first winding is connected with a port 5 of the direct current output end, and the other end of the first winding is connected with one end of the auxiliary power switch tube Q2. The other end of the auxiliary power switch tube Q2 is connected with a port 6 of the direct current output end. One end of a second winding of the transformer T2 is connected with one end of a rectifying diode D7, the other end of the rectifying diode D7 is connected with a port 7 of an auxiliary output end, and the other end of the second winding is connected with a port 8 of the auxiliary output end.
In addition, filter capacitors Co1, cb and Co2 are further arranged in the circuit, wherein the filter capacitor Co1 is connected between a port 3 and a port 4 of the main output end, and filters the main output voltage Vo1 output by the main output end. The filter capacitor Cb is connected between the port 5 and the port 6 of the dc output terminal, and filters the dc output voltage output from the dc output terminal. The filter capacitor Co2 is connected between the port 7 and the port 8 of the auxiliary output end, and filters the auxiliary output voltage Vo2 output by the auxiliary output end.
In one possible embodiment, the voltage stress of the DC/DC auxiliary converter 20 is smaller than a first threshold value, and the current stress of the DC/DC auxiliary converter 20 is smaller than a second threshold value.
In the embodiment of the application, the output power of the DC/DC auxiliary converter 20 is small, the voltage stress of the DC/DC auxiliary converter 20 is smaller than a first threshold value, and the current stress of the DC/DC auxiliary converter 20 is smaller than a second threshold value, thereby reducing the cost of components.
In one possible implementation, the PFC controller 30 further includes a first communication unit, and the DC/DC controller 40 further includes a second communication unit, where the first communication unit establishes a communication connection with the second communication unit.
In the embodiment of the present application, a communication connection is provided between the PFC controller 30 and the DC/DC controller 40, and the PFC controller 30 and the DC/DC controller 40 coordinate respective control and operation based on the communication connection, and a real-time instruction and an operation parameter can be mutually sent between the PFC controller 30 and the DC/DC controller 40, so that a control manner and an adjustment operation state can be set, so that the PFC main converter 10 and the DC/DC auxiliary converter 20 optimally operate, and thus, the performance and reliability of the AC/DC converter can be further improved.
Alternatively, in one possible implementation, the PFC controller 30 and the DC/DC controller 40 may be integrated into one, two or more analog chips, or one, two or more digital chips such as MCUs, DSPs, etc. that require embedded software programming may be used, and the working principle thereof is the same as that of the PFC controller 30 and the DC/DC controller 40 in the above embodiment, and will not be repeated here.
It is to be understood that the application is not limited in its application to the examples described above, but is capable of modification and variation in light of the above teachings by those skilled in the art, and that all such modifications and variations are intended to be included within the scope of the appended claims.

Claims (6)

1. An AC/DC converter, comprising: a power factor correction PFC main converter, a DC/DC auxiliary converter, a PFC controller and a DC/DC controller;
the PFC main converter comprises a main output end and a direct current output end, wherein the direct current output end is connected with an auxiliary input end of the DC/DC auxiliary converter, and the main output end is connected with an auxiliary output end of the DC/DC auxiliary converter in series to form a total output end;
The control end of the PFC controller is connected with the PFC main converter; the control end of the DC/DC controller is connected with the DC/DC auxiliary converter;
The PFC main converter outputs main output voltage through the main output end; the PFC main converter outputs a direct current output voltage through the direct current output end and transmits the direct current output voltage to an auxiliary input end of the DC/DC auxiliary converter; the DC/DC auxiliary converter processes the direct current output voltage to obtain auxiliary output voltage, ripple waves of the auxiliary output voltage are opposite to those of the main output voltage, and the auxiliary output voltage is output through the auxiliary output end;
The total output end receives the main output voltage and the auxiliary output voltage to form a total output voltage; the PFC controller samples a first feedback voltage, and controls the input voltage and the input current of the PFC main converter to have the same frequency and the same phase by using the first feedback voltage; the DC/DC controller samples a second feedback voltage, and utilizes the second feedback voltage to control the ripple wave of the auxiliary output voltage output by the auxiliary output end of the DC/DC auxiliary converter to be opposite to the ripple wave phase of the first voltage;
the first feedback voltage comprises one of the main output voltage and the total output voltage, and the second feedback voltage comprises the total output voltage when the first feedback voltage is the main output voltage; in the case where the first feedback voltage is a total output voltage, the second feedback voltage includes one of the main output voltage and the auxiliary output voltage;
wherein the PFC main converter further comprises a power conversion unit, a main power switch tube and a voltage conversion unit,
The main power switching tube is connected between the output end of the power conversion unit and the input end of the voltage conversion unit, the control end of the main power switching tube is connected with the control end of the PFC controller, and the output end of the voltage conversion unit is connected with the main output end and the direct current output end;
the PFC controller controls the on and off of the main power switch tube;
when the main power switch tube is conducted, the power conversion unit provides electric energy for the voltage conversion unit, and the voltage conversion unit stores the electric energy;
Under the condition that the main power switching tube is cut off, the power conversion unit stops providing electric energy for the voltage conversion unit, and the voltage conversion unit releases the electric energy;
the DC/DC auxiliary converter comprises an auxiliary power switch tube, an inductor and a diode;
One end of the auxiliary power switch tube is connected with one pole of an auxiliary input end of the DC/DC auxiliary converter, the other end of the auxiliary power switch tube is connected with one end of the inductor, the other end of the inductor is connected with one pole of an auxiliary output end, one end of the diode is connected between a source electrode of the auxiliary power switch tube and one end of the inductor, and the other end of the diode is connected between the other pole of the auxiliary input end of the DC/DC auxiliary converter and the other pole of the auxiliary output end;
Under the condition that the auxiliary power switch tube is conducted, the diode is cut off, the auxiliary input end of the DC/DC auxiliary converter receives the direct-current output voltage to provide electric energy for the inductor, and the inductor stores the electric energy;
Under the condition that the auxiliary power switch tube is cut off, the diode is conducted, the inductor, the diode and the auxiliary output end form a current loop, the inductor releases electric energy to provide electric energy for the auxiliary output end, and the auxiliary output end outputs the auxiliary output voltage;
the DC/DC controller comprises a second sampling unit and a second conditioning feedback unit;
The output end of the second sampling unit is connected with the input end of the second conditioning feedback unit, and the output end of the second conditioning feedback unit is connected with the control end of the auxiliary power switch tube;
The second sampling unit is used for: sampling the second feedback voltage; the second conditioning feedback unit is used for: generating a second switch drive signal based on the second feedback voltage; the second switch driving signal is used for controlling the auxiliary power switch tube;
The second conditioning feedback unit comprises a fourth comparator, a fifth comparator, a second reference voltage source and a second sawtooth wave signal source;
the output end of the second reference voltage source is connected with the positive input end of the fourth comparator, and the reverse input end of the fourth comparator is connected with the output end of the second sampling unit; the output end of the fourth comparator is connected with the positive input end of a fifth comparator, the reverse input end of the fifth comparator is connected with the output end of the second sawtooth wave signal source, and the output end of the fifth comparator is connected with the control end of the auxiliary power switch tube;
The fourth comparator is used for comparing the second feedback voltage with the second reference voltage to generate a second voltage error signal; the fifth comparator is used for comparing the second voltage error signal with a second sawtooth wave signal to generate a second switch driving signal, and the second switch driving signal is used for controlling the on and off of the auxiliary power switching tube.
2. An AC/DC converter according to claim 1, characterized in that the voltage converting unit comprises a main winding and an auxiliary winding;
One end of the main winding is connected with one end of the main power switch tube, and the other end of the main winding is connected with the main output end; one end of the auxiliary winding is connected with one end of the main power switch tube, and the other end of the auxiliary winding is connected with the auxiliary output end;
the voltage conversion unit outputs the main output voltage to the main output end through the main winding; the voltage conversion unit outputs the direct-current output voltage to the direct-current output end through the auxiliary winding.
3. The AC/DC converter of claim 2 wherein the PFC controller comprises a first sampling unit and a first conditioning feedback unit;
the output end of the first sampling unit is connected with the input end of the first conditioning feedback unit, and the output unit of the first conditioning feedback unit is connected with the control end of the main power switch tube;
the first sampling unit is used for: sampling the first feedback voltage; the first conditioning feedback unit is used for: generating a first switch drive signal based on the first feedback voltage; the first switch driving signal is used for controlling the on and off of the main power switch tube.
4. An AC/DC converter according to claim 3 wherein the first sampling unit includes a first sampling end, a second sampling end, and a third sampling end; the first conditioning feedback unit includes: the first comparator, the second comparator, the third comparator, the first reference voltage source, the first sawtooth wave signal source and the trigger;
The output end of the first reference voltage source is connected with the positive input end of the first comparator, and the first sampling end is connected with the negative input end of the first comparator; the output end of the first comparator is connected with the positive input end of the second comparator, and the reverse input end of the second comparator is connected with the second sampling end; the output end of the second comparator is connected with the positive input end of the third comparator, the first sawtooth wave signal source is connected with the reverse input end of the third comparator, the output end of the third comparator is connected with the first input end of the trigger, the third sampling end is connected with the second input end of the trigger, and the output end of the trigger is connected with the control end of the main power switch tube;
the first comparator receives a first feedback voltage from the first sampling end and a reference voltage from the reference voltage source, compares the first feedback voltage with the reference voltage, and forms a first voltage error signal;
the second comparator receives a switching tube voltage signal from the second sampling end and a first voltage error signal from the first comparator, compares the first voltage error signal with the switching tube voltage signal to obtain a control signal of the main power switching tube, and the switching tube voltage signal is obtained by converting a current signal of the main power switching tube;
The third comparator receives a current control signal from the second comparator and a first sawtooth wave signal from the first sawtooth wave signal source, and compares the control signal with the sawtooth wave signal to obtain a stop pulse signal; the third sampling end samples the electric energy of the voltage conversion unit to form a starting pulse signal;
the trigger receives the stop pulse signal and the start pulse signal, generates the first switch driving signal based on the start pulse signal and the stop pulse signal, and the first switch driving signal is used for controlling the on and off of the main power switch tube.
5. An AC/DC converter according to claim 1 wherein the voltage stress of the DC/DC auxiliary converter is less than a first threshold and the current stress of the DC/DC auxiliary converter is less than a second threshold.
6. The AC/DC converter of claim 1 wherein the PFC controller comprises a first communication unit and the DC/DC controller comprises a second communication unit, the first communication unit establishing a communication connection with the second communication unit.
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