CN117526688A - Control method, control device and resonant converter - Google Patents

Control method, control device and resonant converter Download PDF

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Publication number
CN117526688A
CN117526688A CN202311395228.0A CN202311395228A CN117526688A CN 117526688 A CN117526688 A CN 117526688A CN 202311395228 A CN202311395228 A CN 202311395228A CN 117526688 A CN117526688 A CN 117526688A
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CN
China
Prior art keywords
voltage signal
resonant converter
resistor
voltage
signal
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Pending
Application number
CN202311395228.0A
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Chinese (zh)
Inventor
邓庭
赵志伟
李依娇
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Shenzhen Nanyun Microelectronics Co ltd
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Shenzhen Nanyun Microelectronics Co ltd
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Priority to CN202311395228.0A priority Critical patent/CN117526688A/en
Publication of CN117526688A publication Critical patent/CN117526688A/en
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Classifications

    • 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
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • 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
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • 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
    • H02M3/01—Resonant DC/DC converters
    • 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
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33571—Half-bridge at primary side of an isolation transformer
    • 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
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33573—Full-bridge at primary side of an isolation transformer

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

Abstract

The invention discloses a control method, a control device and a resonant converter, wherein the control method comprises the following steps: a voltage conversion step, namely receiving a first voltage signal representing the magnitude of the resonant current, generating a second voltage signal after lifting, and generating a bias voltage after bias treatment; a current integration step of integrating the second voltage signal and the bias voltage to generate a ramp voltage signal; a comparison step of comparing the ramp voltage signal with the feedback voltage signal to generate a third voltage signal; and a driving control step, namely setting a slope voltage signal to be a ground potential at the beginning time of each half working period of the resonant converter, controlling the on and off of a primary side switching tube of the resonant converter according to a third voltage signal, controlling the slope voltage signal to be pulled up from the ground potential in the corresponding half working period until the slope voltage signal is larger than a feedback voltage signal, enabling the third voltage signal to be inverted and maintained for a period of time, ending the corresponding half working period, and entering the next half working period. The invention can realize accurate control.

Description

Control method, control device and resonant converter
Technical Field
The invention belongs to the technical field of power electronics and particularly relates to a control method, a control device and a resonant converter.
Background
With the development of a switching power supply to high frequency, high efficiency and high power density, the conventional hard switching technology has some problems in the application process, and in order to solve the problems, the soft switching technology has been developed, and the resonant converter is used as one of soft switches, and has the advantages of small loss, high efficiency, high power density and the like compared with the conventional switching converter, so that the resonant converter has wide attention and application in the industry. When the resonant converter works, the resonant cavity of the resonant converter contains current information of the primary resonant cavity, if a current sampling circuit can be designed in a chip to accurately sample current signals of the resonant cavity, and the sampled resonant current signals are subjected to signal processing of a control circuit, so that the on and off of a power tube in the resonant converter can be accurately controlled, and the reliability of the resonant converter can be effectively improved.
In the resonant converter in the prior art, an alternating current signal in a resonant cavity is firstly converted into an alternating voltage signal by a current sampling circuit, then the alternating voltage signal is subjected to full-wave rectification through a rectifier bridge arranged in a chip, and the chip does not need to process the problem caused by negative pressure, but the number of switching tubes needed by the rectifier bridge circuit is large, the energy loss is large, the efficiency is low, and crossover distortion exists, so that the sampling precision is low.
Disclosure of Invention
In view of the above, the present invention mainly provides a control method, a control device and a resonant converter, which can solve the problems of the prior art to at least a certain extent.
As a first aspect of the present invention, a technical solution of an embodiment of a control method is provided as follows:
a control method applied to a resonant converter, wherein the control method comprises:
a voltage conversion step, namely receiving a first voltage signal representing the magnitude of resonant current in a resonant cavity of the resonant converter, then lifting the first voltage signal to generate a second voltage signal, and carrying out bias treatment on the second voltage signal to generate bias voltage;
a current integration step of generating a ramp voltage signal after integrating the second voltage signal and the bias voltage;
a comparison step of comparing the ramp voltage signal with a feedback voltage signal representing the output voltage of the resonant converter to generate a third voltage signal;
and a driving control step, namely setting the slope voltage signal to be a ground potential at the beginning time of each half working period of the resonant converter, generating a first driving signal and a second driving signal according to the third voltage signal, controlling the on and off of a primary side switching tube of the resonant converter, and controlling the slope voltage signal to start to pull up from the ground potential in the corresponding half working period until the slope voltage signal is larger than the feedback voltage signal, so that the third voltage signal is reversed, and is maintained for a period of time, and the corresponding half working period is ended to enter the next half working period.
Further, in the current integration step, a rising slope of the ramp voltage signal is adjusted by injecting a first current signal.
As a second aspect of the present invention, a technical solution of an embodiment of a control device is provided as follows:
a control device for use in a resonant converter, wherein the control device comprises:
the voltage conversion circuit is used for receiving a first voltage signal representing the magnitude of resonant current in a resonant cavity of the resonant converter, then lifting the first voltage signal to generate a second voltage signal, and carrying out bias treatment on the second voltage signal to generate bias voltage;
the current integration circuit is used for integrating the second voltage signal and the bias voltage to generate a slope voltage signal;
the comparator is used for comparing the slope voltage signal with a feedback voltage signal representing the output voltage of the resonant converter to generate a third voltage signal;
and the driving control circuit is used for setting the slope voltage signal to the ground potential at the starting time of each half working period of the resonant converter, then generating a first driving signal and a second driving signal according to the third voltage signal, controlling the on and off of a primary side switching tube of the resonant converter, and controlling the slope voltage signal to start to pull up from the ground potential in the corresponding half working period until the slope voltage signal is larger than the feedback voltage signal, so that the third voltage signal is reversed, the third voltage signal is maintained for a period of time, and the corresponding half working period is ended, and the next half working period is entered.
Further, the current integrating circuit comprises a current compensating circuit for adjusting the rising slope of the ramp voltage signal by injecting a first current signal.
Preferably, the voltage conversion circuit includes: the device comprises an operational amplifier, an NMOS tube M3, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5 and a resistor R6, wherein the homodromous input end of the operational amplifier is used for inputting a reference voltage Vref1, the output end of the operational amplifier is connected with the grid electrode of the NMOS tube M3, the drain electrode of the NMOS tube M3 is used for inputting a power supply voltage, the source electrode of the NMOS tube M3 is simultaneously connected with one end of the resistor R3, one end of the resistor R5 and one end of the resistor R1, the other end of the resistor R3 and one end of the resistor R4 are connected together and then are connected with the reverse input end of the operational amplifier, the other end of the resistor R5 and one end of the resistor R6 are connected together and then output a second voltage signal Vs, the other end of the resistor R1 and one end of the resistor R2 are connected together and then are used for grounding, and the other end of the resistor R6 is used for inputting a first voltage signal Vr.
Preferably, the current integrating circuit includes: the transconductance amplifier, the switching tube K1, the switching tube K2, the switching tube K3 and the capacitor C2; the second voltage signal Vs is input to the same-direction end of the transconductance amplifier, the bias voltage Va is input to the opposite-direction end of the transconductance amplifier, one output end of the transconductance amplifier is connected with one end of the switch K1, the other output end of the transconductance amplifier is connected with one end of the switch tube K2, the other end of the switch tube K1, the other end of the switch tube K2, one end of the switch tube K3 and one end of the capacitor C2 are connected together and then output the ramp voltage signal Vt, the other end of the switch tube K3 and the other end of the capacitor C2 are connected together and then are grounded, the switch tube K1 is controlled by the first driving signal GH, the switch tube K2 is controlled by the second driving signal GL, and the switch tube K3 is controlled by a narrow pulse enable signal EN generated by the driving control circuit at the starting moment of each half working period of the resonant converter.
As a third aspect of the present invention, a technical solution of an embodiment of a resonant converter is provided as follows:
a resonant converter, wherein: the resonant converter is controlled by the control device according to any one of the second aspects.
Preferably, the resonant converter is a half-bridge resonant converter or a full-bridge resonant converter.
The control method of the resonant converter of the invention, which converts the alternating current signal in the resonant cavity into the alternating current voltage signal and then carries out full-wave rectification on the alternating current voltage signal through the built-in rectifier bridge of the chip, is completely different from the control method of the resonant converter of the prior art, and the specific working principle is described in detail by combining with specific embodiments, which are not repeated herein, and compared with the prior art, the embodiment of the invention has at least the following beneficial effects:
(1) By receiving a first voltage signal representing the magnitude of the resonant current in the resonant cavity of the resonant converter, the first voltage signal is real-time and continuous as a sampling signal, thereby realizing accurate sampling of the resonant current, leading the pulse widths of a first driving signal GH and a second driving signal GL to be equal in the same period, preventing the resonant cavity of the resonant converter from generating a magnetic bias phenomenon, and improving the reliability of the resonant converter;
(2) The first voltage signal is lifted, so that negative pressure in the control device can be avoided, and the design cost of the control device is reduced.
Drawings
FIG. 1 is a flow chart of a control method according to a first embodiment of the present invention;
FIG. 2 is a first schematic diagram of a control device according to a second embodiment of the present invention;
FIG. 3 is a second schematic diagram of a control device according to a second embodiment of the present invention;
FIG. 4 is a schematic illustration of one embodiment of the schematic diagram of FIG. 3;
FIG. 5 is a schematic diagram of a specific circuit of a resonant converter according to a third embodiment of the present invention;
fig. 6 is a waveform diagram of a sample resonant current circuit of the resonant converter of fig. 5 under normal operating conditions using the control device of fig. 4.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. Based on the embodiments in this disclosure, all other embodiments that a person of ordinary skill in the art would obtain without making any inventive effort are within the scope of protection of this disclosure.
It should be noted that the terms "first," "second," and the like in the description and claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe embodiments of the present application herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be understood that in the specification, claims and drawings, when a step is described as being continued to another step, the step may be continued directly to the other step or through a third step to the other step; when an element/unit is described as being "connected" to another element/unit, the element/unit may be "directly connected" to the other element/unit or "connected" to the other element/unit through a third element/unit.
Moreover, the drawings of the present disclosure are schematic representations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus a repetitive description thereof will be omitted. Some of the block diagrams shown in the figures are functional entities and do not necessarily correspond to physically or logically separate entities. The functional entities may be implemented in software or in one or more hardware modules or integrated circuits or in different networks and/or processor devices and/or micro-control devices.
First embodiment
The present embodiment provides a control method applied to a resonant converter, fig. 1 is a flowchart of the control method of the present invention, please refer to fig. 1, wherein the control method includes:
a voltage conversion step of receiving a first voltage signal Vr representing the magnitude of resonant current in a resonant cavity of the resonant converter, then lifting the first voltage signal Vr to generate a second voltage signal Vs, and performing bias processing on the second voltage signal Vs to generate a bias voltage Va;
a current integration step of integrating the second voltage signal Vs and the bias voltage Va to generate a ramp voltage signal Vt;
a comparison step of comparing the ramp voltage signal Vt with a feedback voltage signal VFB representing the output voltage of the resonant converter to generate a third voltage signal Vo;
and a driving control step, setting the slope voltage signal Vt at the beginning time of each half working period of the resonant converter to be a ground potential, then generating a first driving signal GH and a second driving signal GL according to the third voltage signal, controlling the on and off of a primary side switching tube of the resonant converter, and controlling the slope voltage signal Vt to start pulling up from the ground potential in the corresponding half working period until the slope voltage signal Vt is larger than the feedback voltage signal VFB, so that the third voltage signal Vo is reversed, maintaining for a period of time, ending the corresponding half working period, and entering the next half working period.
Compared with the prior art, the control method of the embodiment has at least the following beneficial effects:
(1) The first voltage signal representing the magnitude of the resonant current in the resonant cavity of the resonant converter is received, and the first voltage signal is used as a sampling signal and is real-time and continuous, so that accurate sampling of the resonant current can be realized, pulse widths of a first driving signal GH and a second driving signal GL are equal in the same period, the phenomenon of magnetic bias of the resonant cavity of the resonant converter is prevented, and the reliability of the resonant converter can be improved;
(2) The first voltage signal is lifted, so that negative pressure in the control device can be avoided, and the design cost of the control device is reduced.
Further, in the current integration step, the rising slope of the ramp voltage signal is adjusted by injecting the first current signal, and the value of the first current signal can be adjusted according to different power levels of the resonant converter in practical application, so that the application range of the resonant converter can be effectively widened.
Second embodiment
The present embodiment provides a control device applied to a resonant converter, fig. 2 is a first schematic diagram of the control device of the present invention, please refer to fig. 2, wherein the control device includes:
the voltage conversion circuit 100 is configured to receive a first voltage signal Vr representing a magnitude of a resonant current in a resonant cavity of the resonant converter, then raise the first voltage signal Vr to generate a second voltage signal Vs, and bias the second voltage signal Vs to generate a bias voltage Va;
a current integrating circuit 200 for integrating the second voltage signal Vs and the bias voltage Va to generate a ramp voltage signal Vt;
the comparator 300 is configured to compare the ramp voltage signal Vt with the feedback voltage signal VFB indicating the magnitude of the output voltage of the resonant converter to generate a third voltage signal Vo;
the driving control circuit 400 is configured to set the ramp voltage signal Vt to a ground potential at a start time of each half duty cycle of the resonant converter, then generate the first driving signal GH and the second driving signal GL according to the third voltage signal Vo, control the on and off of the primary side switching tube of the resonant converter, and control the ramp voltage signal Vt to start to pull up from the ground potential in a corresponding half duty cycle until the ramp voltage signal Vt is greater than the feedback voltage signal VFB, so that the third voltage signal Vo is inverted and maintained for a period of time, and the corresponding half duty cycle ends to enter the next half duty cycle.
Fig. 3 is a second schematic diagram of the control device of the present invention, please refer to fig. 3, which is different from fig. 2 in that the current integrating circuit includes a current compensating circuit 201 for adjusting the rising slope of the ramp voltage signal Vt by injecting the first current signal IK. In practical application, the current compensation circuit 201 can be combined with the digital circuit I 2 C is matched with the resonant converter, and the value of the first current signal Ik can be adjusted according to different power levels of the resonant converter, so that the application range of the resonant converter can be effectively widened.
Fig. 4 is a schematic diagram of the schematic diagram of fig. 3, please refer to fig. 4, wherein:
the voltage conversion circuit 100 includes: the device comprises an operational amplifier, an NMOS tube M3, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5 and a resistor R6, wherein the homodromous input end of the operational amplifier is used for inputting a reference voltage Vref1, the output end of the operational amplifier is connected with the grid electrode of the NMOS tube M3, the drain electrode of the NMOS tube M3 is used for inputting a power supply voltage, the source electrode of the NMOS tube M3 is simultaneously connected with one end of the resistor R3, one end of the resistor R5 and one end of the resistor R1, the other end of the resistor R3 and one end of the resistor R4 are connected together and then connected with the reverse input end of the operational amplifier, the other end of the resistor R5 and one end of the resistor R6 are connected together and then output a second voltage signal Vs, the other end of the resistor R1 and one end of the resistor R2 are connected together and then used for grounding, and the other end of the resistor R4 and the resistor R2 are used for inputting a first voltage signal Vr.
Wherein the current integrating circuit 200 includes: the transconductance amplifier, the switching tube K1, the switching tube K2, the switching tube K3 and the capacitor C2; the same-direction end of the transconductance amplifier inputs a second voltage signal Vs, the reverse end of the transconductance amplifier inputs a bias voltage Va, one output end of the transconductance amplifier is connected with one end of a switch K1, the other output end of the transconductance amplifier is connected with one end of a switch tube K2, the other end of the switch tube K1, the other end of the switch tube K2, one end of a switch tube K3 and one end of a capacitor C2 are connected together and then output a slope voltage signal Vt, the other end of the switch tube K3 and the other end of the capacitor C2 are connected together and then are grounded, the switch tube K1 is controlled by a first driving signal GH, the switch tube K2 is controlled by a second driving signal GL, and the switch tube K3 is controlled by a narrow pulse enabling signal EN generated by a driving control circuit at the beginning time of each half working period of the resonant converter.
Third embodiment
The present embodiment provides a resonant converter, wherein: the resonant converter is controlled by the control device of any of the above second embodiments.
Further, the resonant converter is a half-bridge resonant converter or a full-bridge resonant converter.
Fig. 5 is a schematic diagram of a specific circuit of a resonant converter according to a third embodiment of the present invention, please refer to fig. 5, the resonant converter includes a control device, a power tube M1, a power tube M2, a transformer T1, a resonant capacitor Cr, a resonant current conversion device, a feedback voltage loop, an output rectifying and filtering circuit, and a resistor R0 is a load.
In fig. 5, the output end of the control device is connected to the gate of the power tube M1, the drain of the power tube M1 is connected to the positive end of the power source VIN, the source of the power tube M1 is connected to one end of the resonant inductor Ls, the other end of the resonant inductor Ls is connected to the homonymous end of the primary side Lp1 of the transformer T1, the heteronymous end of the primary side Lp1 of the transformer T1 is connected to one end of the resonant current conversion device, the other end of the resonant current conversion device is connected to the resonant capacitor Cr, the source of the power tube M2 and the negative end of the power source VIN are connected together and then connected to the ground, the output end of the resonant current conversion device is connected to the input end of the control device, the other input end of the control device is connected to the output end of the voltage feedback loop, the input end of the voltage feedback loop is connected to one end of the filter capacitor C1, the cathode of the diode D2 is connected to the output end of the resonant converter, the anode of the diode TI of the diode D1 is connected to the homonymous end of the transformer TI secondary side Lp2, the heteronymous end of the secondary side Lp2 of the transformer is connected to the homonymous end of the transformer TI 3, and the heteronymous end of the diode TI of the secondary side Lp2 is connected to the diode TI.
The resonant current conversion device converts the resonant current signal into a resonant voltage signal, namely a first voltage signal Vr, and inputs the resonant voltage signal, the control device can accurately sample the resonant current, a feedback pin of the control device is used for receiving an output feedback voltage signal VFB of the voltage feedback loop, and accordingly, the working frequency of the resonant converter is controlled, and the pulse width of the first driving signal GH) and the pulse width of the second driving signal GL output by the control device are set. The magnetic bias phenomenon of the resonant cavity of the resonant converter is prevented, and the resonant converter can work normally.
The control device adopts the specific circuit of fig. 4, and the working principle of the embodiment is described with reference to fig. 4, and fig. 6 is a waveform diagram of a resonant current circuit sampling of the resonant converter of fig. 5 under the normal working condition of the control device of fig. 4.
The circuit of fig. 4 is based on the clamping effect of the operational amplifier, and the voltages at the same direction input terminal and the opposite direction input terminal of the operational amplifier are equal, so that the voltage signal Vref2 at the connection point between the source electrode of the NMOS transistor M3 and one end of the resistor R3, one end of the resistor R5 and one end of the resistor R1 can be expressed as:
due to the voltage division of the resistors, the second voltage signal Vs can be expressed as:
the bias voltage Va of the second voltage signal Vs can be expressed as:
the resistance of each resistor in each relational expression is directly indicated by the reference numeral of the resistor, and in order to ensure that the bias voltage Va is equal to the dc bias voltage of the second voltage signal Vs, r2=r6 and r1=r5.
The relationship between the bias voltage Va and the second voltage signal Vs can be expressed as:
where Vs_max is the maximum voltage of the second voltage signal Vs, and Vs_min is the minimum voltage of the second voltage signal Vs. The voltage conversion circuit converts the first voltage signal Vr into the second voltage signal Vs and the bias voltage Va of the second voltage signal in real time and continuously, and outputs the second voltage signal Vs and the bias voltage Va to the input terminal of the current integration circuit 200.
In the time t 0-t 1 in fig. 6, the driving control circuit 400 sets the enable signal EN to a high level, turns on the switching tube K3, i.e., the ramp voltage signal Vt is pulled to the ground potential, and the first driving signal GH and the second driving signal GL are both configured to a low level, i.e., the switching tube K1 and the switching tube K2 are turned off, which is a dead time.
At time t1, the enable signal EN is turned to a low level, the first driving signal GH is configured to be a low level, that is, the switching tube K1 and the switching tube K3 are both turned off, the second driving signal GL is turned to a high level, the switching tube K2 is turned on, the transconductance amplifier converts the second voltage signal Vs and the bias voltage Va input thereto into the output current I2 to charge the capacitor C2, so that the ramp voltage signal Vt starts to rise from the ground potential, and the current compensation circuit 201 outputs the first current signal Ik to the input terminal of the current integration circuit, thereby adjusting the slope of the ramp voltage signal Vt until the time when the output current I2 of the transconductance amplifier charges the capacitor C2 to time t 2.
At time t2, when the voltage on the ramp voltage signal Vt is higher than the voltage of the feedback voltage signal VFB input at the non-inverting input terminal of the comparator 300, the third voltage signal Vo output by the comparator 300 is turned to a low level and input to the driving control circuit 400, the driving control circuit 400 turns the second driving signal GL to a low level, the switching tube K2 is turned off, the first driving signal GH is configured to a low level, the switching tube K2 is turned off, the enable signal EN is turned to a high level, the ramp voltage signal Vt is pulled to the ground potential, the comparator outputs the third voltage signal Vo to a high level, the transconductance amplifier stops charging the capacitor C2, and the resonant converter completes the control of half period.
In the time t 2-t 3 in fig. 4, the driving control circuit 400 sets the enable signal EN to a high level, turns on the switching tube K3, i.e., the ramp voltage signal Vt is pulled to the ground potential, and the first driving signal GH and the second driving signal GL are both configured to a low level, i.e., the switching tube K1 and the switching tube K2 are turned off, which is a dead time.
At time t3, the enable signal EN is turned to a low level, the second driving signal GL is configured to a low level, that is, the switching tube K2 and the switching tube K3 are both turned off, the first driving signal GH is turned to a high level, the switching tube K1 is turned on, the transconductance amplifier converts the second voltage signal Vs and the bias voltage Va input thereto into the output current I1 to charge the capacitor C2, so that the ramp voltage signal Vt starts to rise from the ground potential, and the current compensation circuit 201 outputs the first compensation current Ik to the input terminal of the current integration circuit, thereby adjusting the slope of the ramp voltage signal Vt until time t4 when the output current I1 of the transconductance amplifier charges the capacitor C2.
At time t4, when the voltage on the ramp voltage signal Vt is higher than the voltage of the feedback voltage signal VFB input at the non-inverting input terminal of the comparator 300, the third voltage signal Vo output by the comparator 300 is turned to a low level and input to the driving control circuit 400, the driving control circuit 400 turns the first driving signal GH to a low level, the switching tube K1 is turned off, the second driving signal GL is configured to a low level, the switching tube K1 is turned off, the enable signal EN is turned to a high level, the ramp voltage signal Vt is pulled to the ground potential, the comparator outputs the third voltage signal Vo to a high level, the transconductance amplifier stops charging the capacitor C2, and the resonant converter finishes the control of the other half period.
From the moment to t4, the resonant converter completes a complete control period, and the control process is repeated later, so that the analysis of the control process proves that the embodiment of the application realizes the following technical effects:
(1) When the resonant converter works normally, the resonant converter can accurately sample the resonant current by receiving a first voltage signal representing the magnitude of the resonant current in the resonant cavity of the resonant converter, wherein the first voltage signal is used as a sampling signal in real time and continuously, so that pulse widths of a first driving signal GH and a second driving signal GL are equal in the same period, the phenomenon of magnetic bias of the transformer is effectively avoided, and the reliability of the resonant converter can be improved;
(2) The first voltage signal is lifted, so that negative pressure in the control device can be avoided, and the design cost of the control device is reduced;
(3) The current compensation circuit 201 can adjust the rising slope of the ramp voltage signal Vt by outputting the first current signal Ik to the current integration circuit 200; and the current compensation circuit 201 can be matched with the digital circuit I2C for use in practical application, and the value of the first current signal Ik can be adjusted according to different power levels of the resonant converter, so that the application range of a control device in the resonant converter is effectively widened.
While the foregoing is directed to embodiments of the present invention, it will be appreciated by those skilled in the art that changes and modifications may be made without departing from the principles of the invention, the scope of which is defined in the appended claims.

Claims (8)

1. A control method applied to a resonant converter, the control method comprising:
a voltage conversion step, namely receiving a first voltage signal representing the magnitude of resonant current in a resonant cavity of the resonant converter, then lifting the first voltage signal to generate a second voltage signal, and carrying out bias treatment on the second voltage signal to generate bias voltage;
a current integration step of generating a ramp voltage signal after integrating the second voltage signal and the bias voltage;
a comparison step of comparing the ramp voltage signal with a feedback voltage signal representing the output voltage of the resonant converter to generate a third voltage signal;
and a driving control step, namely setting the slope voltage signal to be a ground potential at the beginning time of each half working period of the resonant converter, generating a first driving signal and a second driving signal according to the third voltage signal, controlling the on and off of a primary side switching tube of the resonant converter, and controlling the slope voltage signal to start to pull up from the ground potential in the corresponding half working period until the slope voltage signal is larger than the feedback voltage signal, so that the third voltage signal is reversed, and is maintained for a period of time, and the corresponding half working period is ended to enter the next half working period.
2. The control method according to claim 1, characterized in that: in the current integration step, the rising slope of the ramp voltage signal is adjusted by injecting a first current signal.
3. A control device for use in a resonant converter, the control device comprising:
the voltage conversion circuit is used for receiving a first voltage signal representing the magnitude of resonant current in a resonant cavity of the resonant converter, then lifting the first voltage signal to generate a second voltage signal, and carrying out bias treatment on the second voltage signal to generate bias voltage;
the current integration circuit is used for integrating the second voltage signal and the bias voltage to generate a slope voltage signal;
the comparator is used for comparing the slope voltage signal with a feedback voltage signal representing the output voltage of the resonant converter to generate a third voltage signal;
and the driving control circuit is used for setting the slope voltage signal to the ground potential at the starting time of each half working period of the resonant converter, then generating a first driving signal and a second driving signal according to the third voltage signal, controlling the on and off of a primary side switching tube of the resonant converter, and controlling the slope voltage signal to start to pull up from the ground potential in the corresponding half working period until the slope voltage signal is larger than the feedback voltage signal, so that the third voltage signal is reversed, the third voltage signal is maintained for a period of time, and the corresponding half working period is ended, and the next half working period is entered.
4. A control device according to claim 3, characterized in that: the current integrating circuit comprises a current compensating circuit which is used for adjusting the rising slope of the slope voltage signal through injecting a first current signal.
5. The control device according to claim 3 or 4, characterized in that the voltage conversion circuit includes: the device comprises an operational amplifier, an NMOS tube M3, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5 and a resistor R6, wherein the homodromous input end of the operational amplifier is used for inputting a reference voltage Vref1, the output end of the operational amplifier is connected with the grid electrode of the NMOS tube M3, the drain electrode of the NMOS tube M3 is used for inputting a power supply voltage, the source electrode of the NMOS tube M3 is simultaneously connected with one end of the resistor R3, one end of the resistor R5 and one end of the resistor R1, the other end of the resistor R3 and one end of the resistor R4 are connected together and then are connected with the reverse input end of the operational amplifier, the other end of the resistor R5 and one end of the resistor R6 are connected together and then output a second voltage signal Vs, the other end of the resistor R1 and one end of the resistor R2 are connected together and then are used for grounding, and the other end of the resistor R6 is used for inputting a first voltage signal Vr.
6. The control device according to claim 3 or 4, characterized in that the current integrating circuit includes: the transconductance amplifier, the switching tube K1, the switching tube K2, the switching tube K3 and the capacitor C2; the second voltage signal Vs is input to the same-direction end of the transconductance amplifier, the bias voltage Va is input to the opposite-direction end of the transconductance amplifier, one output end of the transconductance amplifier is connected with one end of the switch K1, the other output end of the transconductance amplifier is connected with one end of the switch tube K2, the other end of the switch tube K1, the other end of the switch tube K2, one end of the switch tube K3 and one end of the capacitor C2 are connected together and then output the ramp voltage signal Vt, the other end of the switch tube K3 and the other end of the capacitor C2 are connected together and then are grounded, the switch tube K1 is controlled by the first driving signal GH, the switch tube K2 is controlled by the second driving signal GL, and the switch tube K3 is controlled by a narrow pulse enable signal EN generated by the driving control circuit at the starting moment of each half working period of the resonant converter.
7. A resonant converter, characterized by: the resonant converter is controlled by a control device according to any one of claims 3 to 6.
8. The vibration transducer of claim 7, wherein: the resonant converter is a half-bridge resonant converter or a full-bridge resonant converter.
CN202311395228.0A 2023-10-25 2023-10-25 Control method, control device and resonant converter Pending CN117526688A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311395228.0A CN117526688A (en) 2023-10-25 2023-10-25 Control method, control device and resonant converter

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311395228.0A CN117526688A (en) 2023-10-25 2023-10-25 Control method, control device and resonant converter

Publications (1)

Publication Number Publication Date
CN117526688A true CN117526688A (en) 2024-02-06

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CN (1) CN117526688A (en)

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