CN116633148A - LLC resonance control circuit, control method thereof and LLC resonance conversion circuit - Google Patents
LLC resonance control circuit, control method thereof and LLC resonance conversion circuit Download PDFInfo
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- CN116633148A CN116633148A CN202310402270.4A CN202310402270A CN116633148A CN 116633148 A CN116633148 A CN 116633148A CN 202310402270 A CN202310402270 A CN 202310402270A CN 116633148 A CN116633148 A CN 116633148A
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- STECJAGHUSJQJN-USLFZFAMSA-N LSM-4015 Chemical compound C1([C@@H](CO)C(=O)OC2C[C@@H]3N([C@H](C2)[C@@H]2[C@H]3O2)C)=CC=CC=C1 STECJAGHUSJQJN-USLFZFAMSA-N 0.000 description 1
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Classifications
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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
- 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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0048—Circuits or arrangements for reducing losses
- H02M1/0054—Transistor switching losses
- H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention provides an LLC resonance control circuit, a control method thereof and an LLC resonance conversion circuit. The LLC resonance control circuit is used for generating a driving signal to drive the half-bridge circuit, the half-bridge circuit comprises a first switching tube and a second switching tube, and the LLC resonance control circuit comprises a judging circuit and an oscillating circuit. The discrimination circuit is used for generating an oscillation control signal according to the resonant cavity sampling current signal representing the resonant cavity current and the soft overcurrent protection threshold. When the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, soft overcurrent protection is triggered, and the judging circuit adjusts the oscillation control signal to reduce the pulse width of the driving signal. The input end of the oscillation circuit is coupled with the judging circuit to acquire an oscillation control signal, and the oscillation circuit is used for generating a pulse modulation signal according to the oscillation control signal to control a driving signal. According to the LLC resonance control circuit, the control method thereof and the LLC resonance conversion circuit, which are provided by the invention, the upper and lower tubes of the half bridge are driven symmetrically, and the reliability of the system is improved.
Description
Technical Field
The invention belongs to the field of power electronics, relates to a resonance control technology, and in particular relates to an LLC resonance control circuit, a control method thereof and an LLC resonance conversion circuit.
Background
Increasing power density and efficiency of power supply systems has been an important research direction for power supply systems. Switching power supplies are used and the switching frequency is increased, but frequency increase also affects switching losses. Therefore, soft switching technology is employed for high frequency switching power supply systems. The LLC resonant converter utilizes the resonance characteristic to enable the switch to work in a soft switching state, and simultaneously has the characteristic of high frequency, so that the LLC resonant converter has higher power density and efficiency of a power supply system.
As shown in fig. 1, the LLC resonant conversion circuit includes a primary side circuit, a secondary side circuit, and a transformer winding. The primary side circuit includes a resonance control circuit and a resonance circuit. The resonance control circuit realizes resonance control through the feedback signal FB and the soft start signal SS, and takes the smaller value of the feedback voltage Vfb and the soft start voltage Vss as the dominant of closed loop control. Taking a voltage-controlled oscillator (VCO for short) as an example, the driving signal driving the first switching tube Q1 is a first driving signal GH, the driving signal driving the second switching tube Q2 is a second driving signal GL, and the on time of the two driving signals is determined by the feedback voltage Vfb and the soft start voltage Vss.
Fig. 2 shows pulse widths of two driving signals respectively corresponding to the first switching tube Q1 and the second switching tube Q2 controlled by the voltage-controlled oscillator when the values of the feedback signal FB and the soft start signal SS are different. Fig. 3 is a schematic diagram of a graph showing the value of the oscillation control signal, where the voltage-controlled oscillator selects the value of the oscillation control signal according to the magnitude relation between the soft start voltage Vss and the feedback voltage Vfb, so as to control the pulse width of the driving signal. As shown in fig. 2 and 3, during the start-up, the soft start voltage Vss gradually increases from 0. When the soft start voltage Vss is smaller than the feedback voltage Vfb (e.g., before time t0 in fig. 3), the voltage-controlled oscillator is controlled by the soft start voltage Vss, which is a soft start control procedure. Specifically, the voltage-controlled oscillator controls the pulse widths of the driving signals of the first switching tube Q1 and the second switching tube Q2 according to the soft start voltage Vss, respectively. When the soft start voltage Vss is greater than the feedback voltage Vfb (e.g., after time t0 in fig. 3), the voltage-controlled oscillator is controlled by the feedback voltage Vfb, i.e., loop closed-loop control. Specifically, the voltage-controlled oscillator controls the pulse width of the first driving signal and the pulse width of the second driving signal according to the feedback voltage Vfb. Since the feedback voltage Vfb is always lower than the soft start voltage Vss after the soft start control voltage Vss reaches the maximum value (e.g., 3.5V), the soft start voltage Vss is no longer involved in control after the soft start is completed, and the system is always controlled by the feedback voltage Vfb.
As shown in fig. 4, when the LLC resonant conversion circuit is in steady state operation (i.e., phase t1-t 2), the pulse width of the first drive signal GH and the pulse width of the second drive signal GL are controlled by the feedback voltage Vfb. When the load is suddenly added to overload or open circuit (at time t 2), the resonant cavity current rises to enable the resonant cavity sampling current signal CS to exceed the overcurrent threshold voltage VOCP_H, so that the resonant control circuit turns off the first switching tube Q1 in advance to enable the pulse width of the first driving signal GH to be shortened, and the pulse width of the second driving signal GL corresponding to the second switching tube Q2 is still controlled by the feedback signal Vfb, thereby causing the system half to trigger the overcurrent protection OCP, the other half not to trigger the overcurrent protection OCP, and the upper half bridge and the lower half bridge to be asymmetric. Similarly, in some cases, the overcurrent protection of the second switching tube may be triggered, so that the pulse width of the second driving signal GL is shortened. The upper and lower half-bridge asymmetry can lead to a series of problems, as follows: (1) The center value of the voltage of the resonance capacitor is deviated, the peak voltage of the resonance capacitor is possibly increased, and overvoltage damage is caused; (2) The load capacity of the system is reduced, and when the overload current is switched back to the full-load current, the load capacity still cannot be recovered; (3) A switching tube (e.g., a second switching tube in the case of fig. 4) that easily causes the non-triggered over-current protection OCP is more likely to enter the capacitive region for operation, reducing system reliability.
In view of the foregoing, there is a need to provide a new architecture or control method for solving at least some of the problems described above.
Disclosure of Invention
The invention provides an LLC resonance control circuit, a control method thereof and an LLC resonance conversion circuit.
According to one aspect of the present invention, an LLC resonant control circuit is disclosed, the LLC resonant control circuit for generating a drive signal to drive a half-bridge circuit, the half-bridge circuit including a first switching tube and a second switching tube, the LLC resonant control circuit comprising:
the input end of the judging circuit is used for acquiring a resonant cavity sampling current signal representing the resonant cavity current and generating an oscillation control signal according to the resonant cavity sampling current signal and a soft overcurrent protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, and regulating an oscillation control signal by a judging circuit to reduce the pulse width of a driving signal; and
and the input end of the oscillation circuit is coupled with the judging circuit to acquire an oscillation control signal, and the oscillation circuit is used for generating a pulse modulation signal according to the oscillation control signal to control a driving signal, wherein the driving signal is used for driving the first switching tube and the second switching tube.
As one embodiment, the soft over-current protection threshold includes a first soft over-current protection threshold and/or a second soft over-current protection threshold, wherein the first soft over-current protection threshold is a positive value, and the second soft over-current protection threshold is a negative value.
As one embodiment, the discrimination circuit includes:
the input end of the charge-discharge control circuit is used for acquiring a resonant cavity sampling current signal and generating a charge-discharge control signal according to the resonant cavity sampling current signal and a soft overcurrent protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, and generating a charge-discharge control signal by a charge-discharge control circuit to control the charge-discharge circuit to discharge; and
and the first end of the charge-discharge circuit is coupled with the oscillation control signal end, and the second end of the charge-discharge circuit is used for receiving a charge-discharge control signal and is used for charging and discharging a capacitor coupled with the oscillation control signal end according to the charge-discharge control signal so as to regulate the oscillation control signal.
As one of the embodiments, the oscillation control signal terminal is a soft start signal terminal or a feedback signal terminal.
As one embodiment, the soft overcurrent protection threshold includes a first soft overcurrent protection threshold and a second soft overcurrent protection threshold, wherein the first soft overcurrent protection threshold is a positive value, and the second soft overcurrent protection threshold is a negative value; the charge-discharge control circuit includes:
The first input end of the first comparison circuit is used for receiving a second soft overcurrent protection threshold value, and the second input end of the first comparison circuit is used for receiving a resonant cavity sampling current signal;
a first input end of the second comparison circuit is used for receiving a resonant cavity sampling current signal, and a second input end of the second comparison circuit is used for receiving a first soft overcurrent protection threshold;
a first OR gate, wherein a first input end of the first OR gate is coupled with the first comparison circuit, and a second input end of the first OR gate is coupled with the second comparison circuit;
an NOT gate, the input end of which is coupled with the output end of the first OR gate;
a second OR gate, the first input end of which is used for receiving the first driving signal, and the second input end of which is used for receiving the second driving signal;
the input end of the falling edge trigger circuit is coupled with the output end of the second OR gate and is used for generating a trigger signal;
and the first input end of the AND gate is coupled with the NOT gate, and the second input end of the AND gate is coupled with the falling edge trigger circuit; and
the setting end of the trigger circuit is coupled with the output end of the first OR gate, the resetting end of the trigger circuit is coupled with the output end of the AND gate, and the output end of the trigger circuit outputs a charge-discharge control signal.
As one embodiment, the soft overcurrent protection threshold includes a first soft overcurrent protection threshold and a second soft overcurrent protection threshold, wherein the first soft overcurrent protection threshold is a positive value, and the second soft overcurrent protection threshold is a negative value; the charge-discharge control circuit includes:
The first input end of the first comparison circuit is used for receiving a second soft overcurrent protection threshold value, and the second input end of the first comparison circuit is used for receiving a resonant cavity sampling current signal;
a first input end of the second comparison circuit is used for receiving a resonant cavity sampling current signal, and a second input end of the second comparison circuit is used for receiving a first soft overcurrent protection threshold;
a first OR gate, wherein a first input end of the first OR gate is coupled with the first comparison circuit, and a second input end of the first OR gate is coupled with the second comparison circuit;
the setting end of the trigger circuit is coupled with the output end of the first OR gate, and the output end of the trigger circuit outputs a charge-discharge control signal; and
and the input end of the delay circuit is coupled with the output end of the trigger circuit, and the output end of the delay circuit is coupled with the reset end of the trigger circuit.
As one embodiment, the charge/discharge circuit includes:
the first end of the first current source is coupled with a preset voltage, and the second end of the first current source is coupled with an oscillation control signal end;
the first end of the first switch is coupled with the oscillation control signal end, and the control end of the first switch is used for receiving the charge and discharge control signal; and
the first end of the second current source is coupled to the second end of the first switch, and the second end of the second current source is coupled to the ground.
As one of the embodiments, the oscillation circuit generates a pulse modulation signal according to the oscillation control signal to control the driving signal, and the pulse width of the driving signal is positively correlated with the oscillation control signal in a preset interval.
As one embodiment, the discriminating circuit includes a valuation circuit for performing a decremental valuation of the oscillation control signal based on a value of the current oscillation control signal to reduce a pulse width of the drive signal when the soft overcurrent protection is triggered.
As another aspect of the invention, an LLC resonant conversion circuit is disclosed, the LLC resonant conversion circuit comprising a primary side circuit, a secondary side circuit and a transformer winding, the primary side circuit comprising an LLC resonant control circuit as described in any of the above.
As still another aspect of the present invention, there is disclosed an LLC resonance control method for generating a drive signal to drive a half-bridge circuit including a first switching tube and a second switching tube, the LLC resonance control method including:
obtaining a resonant cavity sampling current signal representing the current of the resonant cavity, and generating an oscillation control signal according to the resonant cavity sampling current signal and a soft overcurrent protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, and adjusting an oscillation control signal to reduce the pulse width of a driving signal; and
and generating a pulse modulation signal according to the oscillation control signal to control a driving signal, wherein the driving signal is used for driving the first switching tube and the second switching tube.
As one embodiment, the soft over-current protection threshold includes a first soft over-current protection threshold and/or a second soft over-current protection threshold, wherein the first soft over-current protection threshold is a positive value, and the second soft over-current protection threshold is a negative value.
As one implementation mode, generating an oscillation control signal according to the resonant cavity sampling current signal and the soft overcurrent protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, and adjusting the oscillation control signal to reduce the pulse width of the driving signal specifically comprises the following steps:
generating a charge-discharge control signal according to the resonant cavity sampling current signal and the soft overcurrent protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold value, and generating a charge-discharge control signal to control a charge-discharge circuit to discharge, so as to adjust an oscillation control signal to reduce the pulse width of a driving signal; the charge-discharge circuit is coupled with the oscillation control signal end; and
and acquiring a charge-discharge control signal, and charging and discharging a capacitor coupled with the oscillation control signal end according to the charge-discharge control signal so as to adjust the oscillation control signal.
As one of the embodiments, the oscillation control signal terminal is a soft start signal terminal or a feedback signal terminal.
As one of the embodiments, a pulse modulation signal is generated according to the oscillation control signal to control the driving signal, and a pulse width of the driving signal is positively correlated with the oscillation control signal in a preset interval.
The invention provides an LLC resonance control circuit, a control method thereof and an LLC resonance conversion circuit. The LLC resonance control circuit is used for generating a driving signal to drive the half-bridge circuit, the half-bridge circuit comprises a first switching tube and a second switching tube, and the LLC resonance control circuit comprises a judging circuit and an oscillating circuit. The input end of the judging circuit is used for obtaining a resonant cavity sampling current signal representing the resonant cavity current, and the judging circuit is used for generating an oscillation control signal according to the resonant cavity sampling current signal and the soft overcurrent protection threshold. When the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, soft overcurrent protection is triggered, and the judging circuit adjusts the oscillation control signal to reduce the pulse width of the driving signal. The input end of the oscillation circuit is coupled with the judging circuit to acquire an oscillation control signal, and the oscillation circuit is used for generating a pulse modulation signal according to the oscillation control signal to control a driving signal, wherein the driving signal is used for driving the first switching tube and the second switching tube. According to the LLC resonance control circuit, the control method thereof and the LLC resonance conversion circuit, which are provided by the invention, the upper and lower tubes of the half bridge are driven symmetrically, and the reliability of the system is improved.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and together with the description serve to explain the embodiments of the invention, and do not constitute a limitation of the invention. In the drawings:
fig. 1 shows a schematic circuit diagram of a prior art LLC resonant conversion circuit;
FIG. 2 is a diagram showing the relationship between the pulse widths of the feedback signal FB, the soft start signal SS and the driving signal according to the prior art;
FIG. 3 is a graph showing the values of an oscillation control signal according to the prior art;
FIG. 4 shows a schematic waveform of a portion of a signal in a prior art LLC resonant conversion circuit;
FIG. 5 shows a schematic circuit diagram of an LLC resonant conversion circuit according to an embodiment of the invention;
FIG. 6 shows a schematic circuit diagram of an LLC resonant control circuit according to an embodiment of the invention;
fig. 7 is a schematic circuit diagram showing a charge-discharge control circuit according to an embodiment of the present invention;
fig. 8 is a schematic diagram showing a circuit configuration of a charge-discharge control circuit according to another embodiment of the present invention;
fig. 9 shows a schematic waveform diagram of a part of signals in an LLC resonant conversion circuit in accordance with an embodiment of the invention.
Detailed Description
For a further understanding of the present invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are merely intended to illustrate further features and advantages of the invention, and are not limiting of the claims of the invention.
The description of this section is intended to be illustrative of only a few exemplary embodiments and the invention is not to be limited in scope by the description of the embodiments. Combinations of the different embodiments, and alternatives of features from the same or similar prior art means and embodiments are also within the scope of the description and protection of the invention.
"coupled" or "connected" in the specification includes both direct and indirect connections. An indirect connection is a connection via an intermediary, such as a connection via an electrically conductive medium, such as a conductor, where the electrically conductive medium may contain parasitic inductance or parasitic capacitance, or may be a connection via an intermediary circuit or component described in the embodiments of the specification; indirect connections may also include connections through other active or passive devices, such as through circuits or components such as switches, signal amplification circuits, follower circuits, and the like, that may perform the same or similar functions. "plurality" or "multiple" means two or more. In addition, in the present invention, terms such as first and second are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply a certain actual relationship or order between the technical features.
An embodiment of the invention discloses an LLC resonant conversion circuit, which comprises a primary side circuit, a secondary side circuit and a transformer winding as shown in figure 5. The primary side circuit includes an LLC resonant control circuit 10, a half-bridge circuit, and a resonant circuit. The half-bridge circuit comprises a first switching tube Q1 and a second switching tube Q2. The first switching tube Q1 is an upper tube, and the second switching tube Q2 is a lower tube. The first end of the first switching tube Q1 is coupled to the input voltage Vbus, and the control end of the first switching tube Q1 is coupled to the first driving signal output end of the LLC resonance control circuit. The first end of the second switching tube Q2 is coupled to the second end of the first switching tube Q1, the control end of the second switching tube Q2 is coupled to the second driving signal output end of the LLC resonant control circuit, and the second end of the second switching tube Q2 is coupled to the ground. The first driving signal output end is used for outputting a first driving signal to drive the first switching tube Q1, and the second driving signal output end is used for outputting a second driving signal to drive the second switching tube Q2. The resonant circuit includes a first inductance Lr, a second inductance Lm, and a resonant capacitance Cr. The first inductor Lr is coupled in series with the second inductor Lm and the first capacitor Cr. In an embodiment, the primary circuit further includes a first capacitor C1 and a sampling resistor Rcs. The first end of the first capacitor C1 is coupled to the first end of the resonant capacitor Cr, the first end of the sampling resistor Rcs is coupled to the first end of the first capacitor C1, and the second end of the sampling resistor Rcs is coupled to ground. The current sampling terminal CS of the LLC resonant control circuit 10 is coupled to the first terminal of the sampling resistor Rcs to obtain a resonant cavity sampling current signal representing a resonant cavity current, which is a current flowing through the resonant cavity, and the resonant cavity corresponds to the resonant circuit. The feedback signal terminal of the LLC resonant control circuit 10 is arranged to receive a feedback signal indicative of the output voltage of the LLC resonant conversion circuit. The LLC resonant control circuit may output a drive signal based on the resonant cavity sampling current signal to control the resonant cavity current. The LLC resonant control circuit may output a drive signal based on the feedback signal to control an output voltage of the LLC resonant conversion circuit. The soft start signal terminal of the LLC resonant control circuit 10 is coupled to the soft start capacitor Css, and the LLC resonant control circuit performs soft start control according to the soft start signal.
An embodiment of the invention discloses an LLC resonance control circuit which is used for generating a driving signal to drive a half-bridge circuit. The half-bridge circuit comprises a first switching tube Q1 and a second switching tube Q2. As shown in fig. 6, the LLC resonance control circuit includes a discrimination circuit 11, an oscillation circuit 12, and a drive circuit 13. The input end of the discrimination circuit 11 is used for obtaining a resonant cavity sampling current signal representing the resonant cavity current, and the discrimination circuit 11 is used for generating an oscillation control signal according to the resonant cavity sampling current signal and a soft overcurrent protection threshold, wherein the resonant cavity sampling current signal can be a sampling voltage Vcs. When the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, soft overcurrent protection is triggered, and the judging circuit adjusts the oscillation control signal to reduce the pulse width of the driving signal. The resonator sampling current signal reaching the soft overcurrent protection threshold may specifically be that the resonator sampling current signal is equal to or greater than the soft overcurrent protection threshold. The input end of the oscillating circuit 12 is coupled to the output end of the discriminating circuit 11 to obtain an oscillating control signal, and the oscillating circuit 12 is used for generating a pulse modulation signal according to the oscillating control signal to control the driving signal. The driving signal is used for driving the first switching tube and the second switching tube. The input end of the driving circuit 13 is coupled to the output end of the oscillating circuit 12, and the driving circuit 13 outputs a driving signal according to the pulse modulation signal. In one embodiment, the pulse width of the driving signal is positively correlated with the pulse width of the pulse modulated signal. As shown in fig. 6, the driving signals include a first driving signal GH and a second driving signal GL. The first driving signal GH is used for driving the first switching tube Q1, and the second driving signal GL is used for driving the second switching tube Q2. In one embodiment, the driving circuit adjusts the pulse width of the driving signal according to the pulse modulation signal. In another embodiment, as shown in fig. 9, the absolute value of the soft over-current protection threshold is less than the absolute value of the over-current protection threshold. Triggering overcurrent protection when the resonant cavity sampling current signal reaches an overcurrent protection threshold. When the LLC resonance control circuit triggers overcurrent protection, the LLC resonance control circuit controls to turn off the first switching tube and the second switching tube so as to prevent circuit damage. When the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, soft overcurrent protection is triggered, and the judging circuit adjusts the oscillation control signal to reduce the pulse width of the driving signal. In one embodiment, when soft over-current protection is triggered, the LLC resonant control circuit discharges a capacitor coupled to the soft start signal terminal, thereby reducing the soft start voltage and enabling the oscillating circuit to control the pulse width of the driving signal according to the soft start voltage. If soft over-current protection is continuously triggered, the soft start voltage is continuously reduced until soft over-current protection is no longer triggered. At this time, the first driving signal GH and the second driving signal GL of the driving signals are both controlled by the soft start voltage, and thus pulse widths of both the first driving signal GH and the second driving signal GL are symmetrical. In addition, because the soft overcurrent protection is triggered periodically, the soft starting voltage is maintained in a state critical to the soft overcurrent protection, and the system works more stably.
In an embodiment of the present invention, the soft over-current protection threshold includes a first soft over-current protection threshold, and the first soft over-current protection threshold is a positive value. The over-current protection threshold includes a first over-current protection threshold that is positive. The first soft over-current protection threshold is less than the first over-current protection threshold. In another embodiment, the soft over-current protection threshold comprises a second soft over-current protection threshold, the second soft over-current protection threshold being negative. The over-current protection threshold includes a second over-current protection threshold that is negative. The absolute value of the second soft over-current protection threshold is less than the absolute value of the second over-current protection threshold. In yet another embodiment, the soft over-current protection threshold includes a first soft over-current protection threshold that is positive and a second soft over-current protection threshold that is negative. The overcurrent protection threshold comprises a first overcurrent protection threshold and a second overcurrent protection threshold, wherein the first overcurrent protection threshold is a positive value, and the second overcurrent protection threshold is a negative value. The first soft over-current protection threshold is smaller than the first over-current protection threshold, and the absolute value of the second soft over-current protection threshold is smaller than the absolute value of the second over-current protection threshold.
In one embodiment, the discriminating circuit includes a charge-discharge control circuit and a charge-discharge circuit. The input end of the charge-discharge control circuit is used for obtaining the resonant cavity sampling current signal, and the charge-discharge control circuit is used for generating a charge-discharge control signal according to the resonant cavity sampling current signal and the soft overcurrent protection threshold. When the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, soft overcurrent protection is triggered, and the charge-discharge control circuit generates a charge-discharge control signal to control the charge-discharge circuit to discharge. The first end of the charge-discharge circuit is coupled with the oscillation control signal end, the second end of the charge-discharge circuit is coupled with the output end of the charge-discharge control circuit to receive the charge-discharge control signal, and the charge-discharge circuit is used for charging and discharging the capacitor coupled with the oscillation control signal end according to the charge-discharge control signal so as to adjust the oscillation control signal. In an embodiment, the oscillation control signal terminal is a soft start signal terminal, the soft start signal terminal is coupled to the soft start capacitor Css, and the charge-discharge circuit is configured to charge and discharge the capacitor coupled to the soft start signal terminal according to the charge-discharge control signal so as to adjust the oscillation control signal. In another embodiment, the oscillation control signal terminal is a feedback signal terminal, and the feedback signal terminal is coupled to the feedback capacitor. In yet another embodiment, as shown in fig. 5, the charge-discharge circuit includes a first current source is, a first switch, and a second current source is ink. The first end of the first current source I ss is coupled to the preset voltage, and the second end of the first current source I ss is coupled to the oscillation control signal end. The first end of the first switch is coupled to the oscillation control signal end, and the control end of the first switch is used for receiving the charging and discharging control signal Di scharge. The first end of the second current source is coupled to the second end of the first switch, and the second end of the second current source is coupled to ground. When the charge-discharge control signal Di scharge is at a first level (e.g., a high level), the charge-discharge control circuit controls the first switch to be turned on, and discharges a capacitor (e.g., a soft start capacitor Css) coupled to the oscillation control signal terminal (e.g., the soft start signal terminal SS), thereby reducing the voltage of the oscillation control signal terminal.
In another embodiment, the oscillating circuit adjusts the pulse width of the drive signal based on the smaller of the soft start voltage and the feedback voltage as the dominant of the closed loop control. In one embodiment, if the soft start voltage is less than the feedback voltage, the oscillating circuit generates the pulse modulation signal according to the soft start voltage. In another embodiment, if the soft start voltage is greater than the feedback voltage, the oscillation control signal end is a soft start signal end, and when soft overcurrent protection is triggered, the LLC resonant control circuit controls the soft start voltage to decrease to less than the feedback voltage, so that the oscillation circuit generates a pulse modulation signal according to the soft start voltage, and the driving circuit generates a driving signal according to the pulse modulation signal. In one embodiment, as long as the LLC resonant control circuit triggers soft over-current protection, the soft start signal is pulled down until the system reaches a certain equilibrium state (which can be understood as a state where soft over-current protection is not triggered) to achieve adaptive closed-loop control. In another embodiment, when the soft start signal is below a preset value, the LLC resonant control circuit will turn off the first and second switching tubes to further reduce losses (e.g., short circuit losses).
In an embodiment of the present invention, the soft over-current protection threshold includes a first soft over-current protection threshold VSOCPH and a second soft over-current protection threshold VSOCPL, wherein the first soft over-current protection threshold VSOCPH is a positive value, and the second soft over-current protection threshold VSOCPL is a negative value. As shown in fig. 7, the charge-discharge control circuit includes a first comparison circuit 101, a second comparison circuit 102, a first or gate 103, an not gate, a second or gate 104, a falling edge trigger circuit 105, an and gate and trigger circuit 106. The first comparator circuit 101 includes a first comparator U1, wherein a non-inverting input terminal of the first comparator U1 is configured to receive the second soft over-current protection threshold VSOCPL, and an inverting input terminal of the first comparator U1 is configured to receive the resonant cavity sampling current signal CS. The second comparator circuit 102 includes a second comparator U2, wherein a non-inverting input terminal of the second comparator U2 is configured to receive the resonant cavity sampling current signal CS, and an inverting input terminal of the second comparator U2 is configured to receive the first soft over-current protection threshold value VSOCPH. The first input terminal of the first or gate 103 is coupled to the output terminal of the first comparator circuit, and the second input terminal of the first or gate 103 is coupled to the output terminal of the second comparator circuit. The input of the not gate is coupled to the output of the first or gate 103. The first input terminal of the second or gate 104 is configured to receive the first driving signal GH, and the second input terminal of the second or gate 104 is configured to receive the second driving signal GL. An input terminal of the falling edge trigger circuit 105 is coupled to an output terminal of the second or gate 104, and the falling edge trigger circuit 105 is configured to generate a trigger signal. The trigger signal is at a first level (e.g., high) when the output signal of the second or gate 104 is at a falling edge. The first input end of the AND gate is coupled with the NOT gate, and the second input end of the AND gate is coupled with the output end of the falling edge trigger circuit. The trigger circuit 106 includes an RS flip-flop, a set terminal S of the RS flip-flop is coupled to an output terminal of the first or gate 103, a reset terminal R of the RS flip-flop is coupled to an output terminal of the and gate, and an output terminal of the RS flip-flop outputs the charge/discharge control signal Di scharge. When the charge/discharge control signal Di scharge is at a first level (for example, high level), the charge/discharge control circuit controls the charge/discharge circuit to perform discharge. When the charge-discharge control signal Di scharge is at the second level (for example, low level), the charge-discharge control circuit controls the charge-discharge circuit to stop discharging.
In another embodiment of the present invention, the soft over-current protection threshold includes a first soft over-current protection threshold that is positive and a second soft over-current protection threshold that is negative. As shown in fig. 8, the charge-discharge control circuit includes a first comparison circuit 201, a second comparison circuit 202, a first or gate 203, a trigger circuit 206, and a delay circuit 204. The first comparator circuit 201 includes a first comparator U1, a non-inverting input terminal of the first comparator U1 is configured to receive the second soft over-current protection threshold VSOCPL, and an inverting input terminal of the first comparator U1 is configured to receive the resonant cavity sampling current signal CS. The second comparator circuit 202 includes a second comparator U2, wherein a non-inverting input terminal of the second comparator U2 is configured to receive the resonant cavity sampling current signal CS, and an inverting input terminal of the second comparator U2 is configured to receive the first soft over-current protection threshold VSOCPH. The first input terminal of the first or gate 203 is coupled to the output terminal of the first comparator, and the second input terminal of the first or gate 203 is coupled to the output terminal of the second comparator. The trigger circuit 206 includes an RS flip-flop, a set terminal of which is coupled to an output terminal of the first or gate 203, and an output terminal of which outputs the charge-discharge control signal Di scharge. The input end of the delay circuit 204 is coupled to the output end of the trigger circuit, and the output end of the delay circuit 204 is coupled to the reset end of the RS trigger. The delay circuit 204 is configured to reset the trigger circuit after a delay of a preset time when the charge-discharge control signal Di scharge starts to be at a first level (e.g., a high level), so as to control a discharge time of the charge-discharge circuit to avoid overdischarge.
In yet another embodiment, the soft over-current protection threshold comprises a first soft over-current protection threshold that is positive. The charge-discharge control circuit includes a second comparison circuit, a trigger circuit, and a delay circuit. The second comparator circuit comprises a second comparator, wherein the non-inverting input end of the second comparator is used for receiving the resonant cavity sampling current signal CS, and the inverting input end of the second comparator is used for receiving the first soft overcurrent protection threshold VSOCPH. The trigger circuit comprises an RS trigger, wherein the set end of the RS trigger is coupled with the output end of the second comparator, and the output end of the RS trigger outputs a charge-discharge control signal Di scharge. The input end of the delay circuit is coupled with the output end of the trigger circuit, and the output end of the delay circuit is coupled with the reset end of the RS trigger.
In one embodiment, the oscillation circuit generates a pulse modulation signal according to the oscillation control signal to control the driving signal, and the pulse width of the driving signal is positively correlated with the oscillation control signal in a preset interval. In another embodiment, the pulse width of the driving signal is proportional to the oscillation control signal in a preset interval. In practical applications, the pulse width of the driving signal and the oscillation control signal in the preset interval may be designed to be inversely related, but the related control logic becomes more complex.
In an embodiment, the LLC resonant control circuit is a voltage mode controlled LLC resonant control circuit or a current mode controlled LLC resonant control circuit. In another embodiment, the LLC resonant control circuit controls an envelope area of the forward current of the resonant cavity sampling current signal to be proportional to the soft start voltage.
In one embodiment, the discrimination circuit includes a soft over-current protection discrimination circuit and a valuation circuit. The soft overcurrent protection judging circuit is used for triggering soft overcurrent protection when the resonant cavity sampling current signal reaches a soft overcurrent protection threshold. The assignment circuit is used for carrying out decremental assignment on the oscillation control signal based on the value of the current oscillation control signal so as to reduce the pulse width of the driving signal when the soft overcurrent protection is triggered. The assignment circuit may end the decremental assignment when the resonator sampling current signal does not reach the soft over-current protection threshold.
As shown in fig. 9, in an embodiment of the present invention, the first driving signal GH is used to control the switching state of the first switching transistor Q1, and the second driving signal GL is used to control the switching state of the second switching transistor Q2. The first switching tube Q1 and the second switching tube Q2 alternately perform switching operation. In order to avoid that the first switching tube Q1 and the second switching tube Q2 are turned on at the same time, a dead zone is provided. The waveform of the sine-like wave variation in fig. 9 is the sampling voltage Vcs, i.e., the resonant cavity sampling current signal is the sampling voltage Vcs. Before time t1, the LLC resonant conversion circuit works normally. At time t1, the sampling voltage Vcs reaches a first soft over-current protection threshold VSOCPH of the soft over-current protection thresholds, triggering soft over-current protection. As can be seen from fig. 7 and 9, at time t1, the output signal SCOP of the first or gate 103 is at a first level (e.g., high level), the charge/discharge control circuit controls the charge/discharge circuit to start discharging, and when the trigger signal output from the falling edge trigger circuit 105 is at the first level (e.g., high level), the RS trigger resets, and the charge/discharge control circuit controls the charge/discharge circuit to stop discharging. Before time t1, since the charge-discharge control circuit controls the charge-discharge circuit to continue charging, the soft start signal SS (e.g., soft start voltage Vss) gradually increases. In the period from t1 to t2, the soft start signal SS gradually decreases since the charge-discharge control circuit controls the charge-discharge circuit to continue discharging. In the period between t2 and t3, since soft overcurrent protection is not triggered, the charge-discharge control circuit controls the charge-discharge circuit to continue charging, and the soft start signal SS (e.g., soft start voltage Vss) gradually rises. At time t3, the sampling voltage Vcs reaches a first soft overcurrent protection threshold VSOCPH of the soft overcurrent protection thresholds again, soft overcurrent protection is triggered, and the LLC resonant control circuit gradually reduces the control soft start signal SS. As shown in fig. 9, the soft over-current protection threshold further includes a second soft over-current protection threshold VSOCPL, and if the sampling voltage Vcs reaches the second soft over-current protection threshold VSOCPL of the soft over-current protection thresholds, soft over-current protection is triggered. And an overcurrent protection threshold is further arranged in the LLC resonant control circuit, and the overcurrent protection threshold comprises a first soft overcurrent protection threshold VOCPH and a second soft overcurrent protection threshold VOCPL. The first soft over-current protection threshold value VSOCPH is smaller than the first over-current protection threshold value VOCPH, and the absolute value of the second soft over-current protection threshold value VSOCPL is smaller than the absolute value of the second over-current protection threshold value VOCPL. When the over-current protection is triggered, the LLC resonance control circuit controls the first switching tube and the second switching tube to be turned off so as to prevent the circuit from being damaged.
Based on the LLC resonant circuit and related improvement, the soft overcurrent protection function is adopted, so that the overcurrent state of the system can be effectively suppressed by suppressing the soft start voltage Vss, and the phenomenon that the system stops working due to direct triggering of overcurrent protection is reduced. In addition, because the upper and lower tube driving is controlled by the soft start voltage Vss, the system driving signals are symmetrical (namely the first driving signal and the second driving signal are relatively symmetrical), so that the voltage center value of the resonance capacitor is stabilized at the middle point of the bridge arm, and the reliability of the resonance capacitor is improved. In addition, the upper and lower pipes of the system are symmetrically driven, so that the system is favorable for recovering from an overload state, the system can be set with a lower overcurrent threshold, the current peak value of the system is effectively reduced, the limiting current and voltage of devices such as a transformer inductor are reduced, and the cost of the system is reduced. In addition, the upper pipe and the lower pipe of the system are symmetrically driven, so that LLC resonance working waveforms are more stable, the reliability of the system is improved, the working noise is reduced, and the like.
Another embodiment of the invention also discloses an LLC resonant conversion circuit comprising a primary side circuit, a secondary side circuit and a transformer winding, the primary side circuit comprising an LLC resonant control circuit as described in any of the preceding claims.
The invention also discloses an LLC resonance control method, which is used for generating a driving signal to drive a half-bridge circuit, wherein the half-bridge circuit comprises a first switch tube and a second switch tube, and the LLC resonance control method comprises the following steps:
obtaining a resonant cavity sampling current signal representing the current of the resonant cavity, and generating an oscillation control signal according to the resonant cavity sampling current signal and a soft overcurrent protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, and adjusting an oscillation control signal to reduce the pulse width of a driving signal; and
and generating a pulse modulation signal according to the oscillation control signal to control a driving signal, wherein the driving signal is used for driving the first switching tube and the second switching tube.
In one embodiment, the LLC resonance control circuit comprises a discrimination circuit and an oscillation circuit, and the LLC resonance control method comprises the discrimination circuit generating an oscillation control signal according to a resonant cavity sampling current signal and a soft overcurrent protection threshold; when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, triggering soft overcurrent protection, and adjusting an oscillation control signal to reduce the pulse width of a driving signal. The oscillation circuit generates a pulse modulation signal according to the oscillation control signal to control the driving signal.
In an embodiment, the soft over-current protection threshold comprises a first soft over-current protection threshold and/or a second soft over-current protection threshold, the first soft over-current protection threshold being positive and the second soft over-current protection threshold being negative.
In another embodiment, the oscillation control signal is generated according to the resonant cavity sampling current signal and the soft overcurrent protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, and adjusting the oscillation control signal to reduce the pulse width of the driving signal specifically comprises the following steps: generating a charge-discharge control signal according to the resonant cavity sampling current signal and the soft overcurrent protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold value, and generating a charge-discharge control signal to control a charge-discharge circuit to discharge, so as to adjust an oscillation control signal to reduce the pulse width of a driving signal; the charge-discharge circuit is coupled with the oscillation control signal end; and acquiring a charge-discharge control signal, and charging and discharging a capacitor coupled with the oscillation control signal end according to the charge-discharge control signal so as to adjust the oscillation control signal.
In yet another embodiment, the oscillation control signal terminal is a soft start signal terminal or a feedback signal terminal.
In one embodiment, the pulse modulation signal is generated according to the oscillation control signal to control the driving signal, and the pulse width of the driving signal is positively correlated with the oscillation control signal in a preset interval.
It will be appreciated by those skilled in the art that the logic controls of the "high" and "low", "set" and "reset", "and" or "," in-phase input "and" anti-phase input "among the logic controls described in the specification or drawings may be interchanged or changed, and that the same functions or purposes as those of the above embodiments may be achieved by adjusting the subsequent logic controls.
The description and applications of the present invention herein are illustrative and are not intended to limit the scope of the invention to the embodiments described above. The relevant descriptions of effects, advantages and the like in the description may not be presented in practical experimental examples due to uncertainty of specific condition parameters or influence of other factors, and the relevant descriptions of effects, advantages and the like are not used for limiting the scope of the invention. Variations and modifications of the embodiments disclosed herein are possible, and alternatives and equivalents of the various components of the embodiments are known to those of ordinary skill in the art. It will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, and with other assemblies, materials, and components, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.
Claims (15)
1. An LLC resonant control circuit for generating a drive signal to drive a half-bridge circuit, the half-bridge circuit including a first switching tube and a second switching tube, the LLC resonant control circuit comprising:
the input end of the judging circuit is used for acquiring a resonant cavity sampling current signal representing the resonant cavity current and generating an oscillation control signal according to the resonant cavity sampling current signal and a soft overcurrent protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, and regulating an oscillation control signal by a judging circuit to reduce the pulse width of a driving signal; and
and the input end of the oscillation circuit is coupled with the judging circuit to acquire an oscillation control signal, and the oscillation circuit is used for generating a pulse modulation signal according to the oscillation control signal to control a driving signal, wherein the driving signal is used for driving the first switching tube and the second switching tube.
2. The LLC resonant control circuit of claim 1, wherein the soft over-current protection threshold includes a first soft over-current protection threshold that is positive and/or a second soft over-current protection threshold that is negative.
3. The LLC resonant control circuit of claim 1, wherein the discrimination circuit includes:
The input end of the charge-discharge control circuit is used for acquiring a resonant cavity sampling current signal and generating a charge-discharge control signal according to the resonant cavity sampling current signal and a soft overcurrent protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, and generating a charge-discharge control signal by a charge-discharge control circuit to control the charge-discharge circuit to discharge; and
and the first end of the charge-discharge circuit is coupled with the oscillation control signal end, and the second end of the charge-discharge circuit is used for receiving a charge-discharge control signal and is used for charging and discharging a capacitor coupled with the oscillation control signal end according to the charge-discharge control signal so as to regulate the oscillation control signal.
4. A LLC resonant control circuit according to claim 3, wherein the oscillation control signal terminal is a soft start signal terminal or a feedback signal terminal.
5. A LLC resonant control circuit according to claim 3, wherein the soft over-current protection threshold comprises a first soft over-current protection threshold value and a second soft over-current protection threshold value, the first soft over-current protection threshold value being positive and the second soft over-current protection threshold value being negative; the charge-discharge control circuit includes:
the first input end of the first comparison circuit is used for receiving a second soft overcurrent protection threshold value, and the second input end of the first comparison circuit is used for receiving a resonant cavity sampling current signal;
A first input end of the second comparison circuit is used for receiving a resonant cavity sampling current signal, and a second input end of the second comparison circuit is used for receiving a first soft overcurrent protection threshold;
a first OR gate, wherein a first input end of the first OR gate is coupled with the first comparison circuit, and a second input end of the first OR gate is coupled with the second comparison circuit;
an NOT gate, the input end of which is coupled with the output end of the first OR gate;
a second OR gate, the first input end of which is used for receiving the first driving signal, and the second input end of which is used for receiving the second driving signal;
the input end of the falling edge trigger circuit is coupled with the output end of the second OR gate and is used for generating a trigger signal;
and the first input end of the AND gate is coupled with the NOT gate, and the second input end of the AND gate is coupled with the falling edge trigger circuit; and
the setting end of the trigger circuit is coupled with the output end of the first OR gate, the resetting end of the trigger circuit is coupled with the output end of the AND gate, and the output end of the trigger circuit outputs a charge-discharge control signal.
6. A LLC resonant control circuit according to claim 3, wherein the soft over-current protection threshold comprises a first soft over-current protection threshold value and a second soft over-current protection threshold value, the first soft over-current protection threshold value being positive and the second soft over-current protection threshold value being negative; the charge-discharge control circuit includes:
The first input end of the first comparison circuit is used for receiving a second soft overcurrent protection threshold value, and the second input end of the first comparison circuit is used for receiving a resonant cavity sampling current signal;
a first input end of the second comparison circuit is used for receiving a resonant cavity sampling current signal, and a second input end of the second comparison circuit is used for receiving a first soft overcurrent protection threshold;
a first OR gate, wherein a first input end of the first OR gate is coupled with the first comparison circuit, and a second input end of the first OR gate is coupled with the second comparison circuit;
the setting end of the trigger circuit is coupled with the output end of the first OR gate, and the output end of the trigger circuit outputs a charge-discharge control signal; and
and the input end of the delay circuit is coupled with the output end of the trigger circuit, and the output end of the delay circuit is coupled with the reset end of the trigger circuit.
7. An LLC resonant control circuit according to claim 3, wherein the charge-discharge circuit comprises:
the first end of the first current source is coupled with a preset voltage, and the second end of the first current source is coupled with an oscillation control signal end;
the first end of the first switch is coupled with the oscillation control signal end, and the control end of the first switch is used for receiving the charge and discharge control signal; and
the first end of the second current source is coupled to the second end of the first switch, and the second end of the second current source is coupled to the ground.
8. The LLC resonant control circuit of claim 1 wherein the oscillating circuit generates a pulse modulated signal based on the oscillation control signal to control the drive signal, the pulse width of the drive signal being in positive correlation with the oscillation control signal over a predetermined interval.
9. An LLC resonant control circuit as claimed in claim 1, wherein the discrimination circuit includes a valuation circuit for decrementing the oscillation control signal based on the value of the current oscillation control signal to reduce the pulse width of the drive signal when soft over-current protection is triggered.
10. An LLC resonant conversion circuit comprising a primary side circuit, a secondary side circuit and a transformer winding, characterized in that the primary side circuit comprises an LLC resonant control circuit according to any of the claims 1-9.
11. An LLC resonance control method for generating a drive signal to drive a half-bridge circuit including a first switching tube and a second switching tube, the LLC resonance control method comprising:
obtaining a resonant cavity sampling current signal representing the current of the resonant cavity, and generating an oscillation control signal according to the resonant cavity sampling current signal and a soft overcurrent protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, and adjusting an oscillation control signal to reduce the pulse width of a driving signal; and
and generating a pulse modulation signal according to the oscillation control signal to control a driving signal, wherein the driving signal is used for driving the first switching tube and the second switching tube.
12. The LLC resonant control method according to claim 11, wherein the soft over-current protection threshold includes a first soft over-current protection threshold value that is positive and/or a second soft over-current protection threshold value that is negative.
13. The LLC resonant control method of claim 11, wherein the oscillation control signal is generated based on the resonant cavity sampling current signal and a soft over-current protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold, and adjusting the oscillation control signal to reduce the pulse width of the driving signal specifically comprises the following steps:
generating a charge-discharge control signal according to the resonant cavity sampling current signal and the soft overcurrent protection threshold; triggering soft overcurrent protection when the sampling current signal of the resonant cavity reaches a soft overcurrent protection threshold value, and generating a charge-discharge control signal to control a charge-discharge circuit to discharge, so as to adjust an oscillation control signal to reduce the pulse width of a driving signal; the charge-discharge circuit is coupled with the oscillation control signal end; and
and acquiring a charge-discharge control signal, and charging and discharging a capacitor coupled with the oscillation control signal end according to the charge-discharge control signal so as to adjust the oscillation control signal.
14. The LLC resonant control method of claim 13, wherein the oscillation control signal terminal is either a soft start signal terminal or a feedback signal terminal.
15. The LLC resonant control method according to claim 11, wherein the pulse modulation signal is generated in response to the oscillation control signal to control the drive signal, the pulse width of the drive signal being in positive correlation with the oscillation control signal over a predetermined interval.
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| CN202310402270.4A CN116633148A (en) | 2023-04-11 | 2023-04-11 | LLC resonance control circuit, control method thereof and LLC resonance conversion circuit |
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| CN202310402270.4A CN116633148A (en) | 2023-04-11 | 2023-04-11 | LLC resonance control circuit, control method thereof and LLC resonance conversion circuit |
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