CN112953175A - Isolated voltage conversion system and primary side control circuit and method - Google Patents
Isolated voltage conversion system and primary side control circuit and method Download PDFInfo
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- CN112953175A CN112953175A CN202110276144.XA CN202110276144A CN112953175A CN 112953175 A CN112953175 A CN 112953175A CN 202110276144 A CN202110276144 A CN 202110276144A CN 112953175 A CN112953175 A CN 112953175A
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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
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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
- H02M1/14—Arrangements for reducing ripples from dc input or output
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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
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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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Abstract
The invention provides an isolated voltage conversion system, a primary side control circuit thereof and a line voltage feedforward compensation method. The primary side control circuit includes: the first control circuit is used for controlling the primary side switch to be switched from a first state to a second state when the quasi-resonance state is met; the second control circuit is used for switching the primary side switch from the second state to the first state when the primary side current rises to the reference threshold value; wherein the second control circuit includes a line voltage compensation circuit for generating a compensation signal based on the line voltage and compensating for the reference threshold. The system, the primary side control circuit and the method thereof can effectively reduce the ripple of the output voltage in the quasi-resonance controlled isolated voltage conversion circuit.
Description
Technical Field
The invention relates to the field of electronics, in particular but not exclusively to an isolated voltage conversion system, a primary side control circuit thereof and a line voltage feedforward compensation method.
Background
The isolated converter is widely applied to the field of switching power supplies due to the advantages of strong anti-jamming capability, high safety, easiness in realizing buck-boost conversion, easiness in realizing multi-path output and the like. The isolated converter generally includes a rectifying circuit, a primary side circuit, a secondary side circuit, and the like. The isolated converter can be safely and stably output through the accurate control of the original secondary side control circuit. The primary side feedback control (PSR) which adopts the auxiliary winding added in the transformer for feedback is widely applied to low-power Alternating Current and Direct Current (ACDC) because an optical coupler is not needed to be used as primary and secondary side communication, thereby saving the cost. Quasi-resonance (QR) control is a common control strategy in a PSR system, a primary side switch tube of the QR system is conducted at the bottom of a drain voltage resonance valley of a primary side switch, so that the loss of the switch is reduced, and the system efficiency is improved.
In an isolated voltage conversion system, the energy transmitted by the primary side to the secondary side and the energy consumed by the output voltage on the load satisfy the law of conservation of energy neglecting the transformer losses and the energy consumed by the control loop itself. In a power frequency period, the energy consumed by the input end of the quasi-resonant isolated voltage conversion circuit is equal to 0.5C (Vpeak)2-Vvalley2) The energy consumed by the load is equal to Vout Iout T, where C is the input capacitance and Vpeak and Vvalley are the peak and valley of the line voltage after the bridge, respectively. Vpeak is a peak of an input end line voltage of the input voltage isolation type voltage transformation circuit, Vvalley is a valley of the line voltage, and 0.5C (Vpeak + Vvalley) (Vpeak-Vvalley) Vout lout. When the load is fixed, the ripple of the line voltage at the high-voltage input is small, and the ripple of the line voltage at the low-voltage input is large.
In the existing regulation mechanism, when the output voltage changes due to the change of the line voltage, the control loop adjusts the reference of the primary side current peak value according to the output voltage feedback signal. However, due to the existence of the low-pass filter module in the control loop, the speed of adjusting the primary side current peak value is too slow, the adjustment amplitude is not enough, and the output voltage ripple is large. On the other hand, in the flyback voltage conversion system, when the line voltage decreases, the output energy decreases, the control loop needs to control the peak value of the primary side current to increase, and then the peak value of the secondary side current also increases, which increases the working period, causes the frequency to decrease, and causes the further decrease of the primary side supplementary energy to increase the output voltage ripple. Therefore, the QR system has a defect of large output voltage ripple especially under low voltage and heavy load.
In view of the above, there is a need to provide a new structure or control method to solve at least some of the above problems.
Disclosure of Invention
The invention provides an isolation type voltage conversion system, a primary side control circuit thereof and a line voltage feedforward compensation method, aiming at one or more problems in the prior art.
According to one aspect of the present invention, a primary side control circuit for an isolated voltage conversion circuit includes: the first control circuit provides a first control signal for controlling the primary side switch to be switched from a first state to a second state when the isolated voltage conversion circuit meets the quasi-resonance state; the second control circuit provides a second control signal for switching the primary side switch from the second state to the first state when the primary side current rises to the reference threshold; the second control circuit comprises a line voltage compensation circuit, the line voltage compensation circuit is used for acquiring a line voltage signal representing the line voltage at the input end of the isolated voltage conversion circuit and generating a compensation signal based on the line voltage signal, and the second control circuit adopts the compensation signal to compensate the reference threshold.
In one embodiment, the second control circuit further comprises: a current reference signal generating circuit that generates a current reference signal; an addition circuit that generates a compensated current reference signal based on the current reference signal and the compensation signal; and the comparison circuit is used for comparing a current sampling signal representing the current flowing through the primary side switch with the compensated current reference signal and providing a second control signal for switching the primary side switch from the on state to the off state based on the comparison result.
In one embodiment, the second control circuit further comprises: a current reference signal generating circuit that generates a current reference signal; a subtraction circuit that generates a compensated current sampling signal based on a difference between a current sampling signal representing a current flowing through the primary side switch and the compensation signal; and the comparison circuit is used for comparing the compensated current sampling signal with the current reference signal and providing a second control signal based on the comparison result so as to switch the primary side switch from the on state to the off state.
In one embodiment, the second control circuit further comprises: a current reference signal generating circuit that generates a current reference signal; and the compensation comparison circuit is provided with a first input end, a second input end, a third input end and an output end, wherein the first input end receives a current sampling signal representing the current flowing through the primary side switch, the second input end receives a current reference signal, the third input end receives a compensation signal, and the output end of the compensation comparison circuit provides a second control signal for switching off the primary side switch.
In one embodiment, the line voltage compensation circuit comprises a current control voltage source, wherein an input end of the current control voltage source is coupled with an auxiliary winding of the isolated voltage conversion circuit, and an output end of the current control voltage source provides the compensation signal.
In one embodiment, the current-controlled voltage source comprises: the current mirror acquires a line voltage current signal which is in direct proportion to the line voltage; the current conversion circuit is used for acquiring a difference current signal between the reference current and the line voltage current signal; and the input end of the current-voltage conversion circuit is coupled with the output end of the current conversion circuit and the resistor, and the output end of the current-voltage conversion circuit provides a voltage signal which is in direct proportion to the difference current signal as a compensation signal.
In one embodiment, the current-to-voltage conversion circuit further receives an upper current reference signal, and the compensation signal is limited by the upper current reference signal when the product of the difference current signal and the resistance is greater than the upper current reference signal.
In one embodiment, the isolated voltage conversion circuit includes a flyback voltage conversion circuit, a primary switch having a first end, a second end, and a control end, the first end of the primary switch being coupled to the second end of a primary winding of the isolated voltage conversion circuit, the first end of the primary winding receiving a line voltage, the second end of the primary switch being coupled to a sampling resistor for providing a current sampling signal reflecting a primary current, the other end of the sampling resistor being coupled to a primary ground, the control end of the primary switch being coupled to an output end of the primary control circuit, wherein the first control circuit turns on the primary switch when a voltage at the first end of the primary switch drops to a valley bottom.
In one embodiment, the primary side control circuit further comprises a trigger circuit having a first input terminal coupled to the output terminal of the first control circuit, a second input terminal coupled to the output terminal of the second control circuit, and an output terminal coupled to the control terminal of the primary side switch.
In one embodiment, the first state is an off state and the second state is an on state.
In one embodiment, the current reference signal generating circuit includes: the input end of the sampling and holding circuit is coupled with the auxiliary winding of the isolated voltage conversion circuit and used for acquiring a feedback signal, and the output end of the sampling and holding circuit provides a sampling and holding signal for sampling and holding the feedback signal; the input end of the error amplifying circuit is coupled with the output end of the sampling and holding circuit; the input end of the low-pass filter circuit is coupled with the output end of the error amplifying circuit; and an amplitude modulation circuit, the input end of which is coupled to the output end of the low-pass filter circuit, and the output end of which provides a current reference signal.
According to another aspect of the present invention, an isolated voltage conversion system includes: the input end of the rectification circuit is coupled with a commercial power alternating current power supply, and the output end of the rectification circuit provides line voltage; the input end of the isolated voltage conversion circuit is coupled with the output end of the rectifying circuit, and the output end of the isolated voltage conversion circuit provides output voltage for driving a load; and a primary side control circuit as described in any of the above embodiments.
In one embodiment, an isolated voltage translation circuit includes: a primary winding, the first end of which is coupled with the output end of the rectifying circuit;
a first end of the primary side switch is coupled with a second end of the primary side winding; a first end of the sampling resistor is coupled with a second end of the primary side switch, and a second end of the sampling resistor is coupled with a primary side ground; the secondary winding is coupled with the primary winding and is coupled with the secondary rectifying tube and provides output voltage; the auxiliary winding is coupled with the primary winding and used for providing a feedback signal for representing the change of the output voltage; the first input end of the primary side control circuit is coupled with the second end of the primary side switch, the second input end of the primary side control circuit is coupled with the auxiliary winding, and the output end of the primary side control circuit is coupled with the control end of the primary side switch.
According to another aspect of the present invention, a primary side control circuit for an isolated voltage converting circuit is provided, wherein an input terminal of the isolated voltage converting circuit receives a line voltage, an output terminal of the isolated voltage converting circuit is coupled to a load, the isolated voltage converting circuit employs quasi-resonance control and primary side feedback control, the primary side control circuit is configured to turn off a primary side switch when a current sampling signal representing a current flowing through the primary side switch of the isolated voltage converting circuit reaches a current reference signal, and the primary side control circuit further generates a compensation signal based on the line voltage and uses the compensation signal for compensating the current sampling signal or the current reference signal.
In one embodiment, the isolated voltage converting circuit includes a primary winding, a secondary winding, and an auxiliary winding, and the primary control circuit includes: the quasi-resonance primary side control circuit is coupled with the auxiliary winding and controls the conduction of the primary side switch when the feedback voltage on the auxiliary winding is at the valley bottom position; the current reference signal generating circuit is coupled with the auxiliary winding and generates a current reference signal based on the feedback voltage; and a line voltage compensation circuit coupled to the auxiliary winding, the line voltage compensation circuit obtaining a voltage signal representative of the line voltage based on a current signal on the auxiliary winding and generating a compensation signal.
According to another aspect of the invention, a line voltage feedforward compensation method for an isolated voltage conversion circuit comprises the following steps: when the isolated voltage conversion circuit meets the quasi-resonance state, the primary side switch is switched from a first state to a second state; when the primary side current rises to a reference threshold value, the primary side switch is switched from a second state to a first state; and compensating the primary side current peak value according to the ripple wave of the line voltage at the input end of the isolated voltage conversion circuit.
In one embodiment, a method for compensating a primary side current peak value according to a ripple of a line voltage at an input end of an isolated voltage conversion circuit comprises the following steps: generating a compensation signal based on the line voltage; generating a current reference signal based on an output voltage of the isolated voltage conversion circuit; acquiring a current sampling signal representing current flowing through a primary side switch; the compensation of the reference threshold is achieved by adding the compensation signal to the current reference signal or subtracting the compensation signal from the current sample signal.
In one embodiment, the isolated voltage conversion circuit comprises a primary side switch, and a primary side winding, a secondary side winding and an auxiliary winding which are coupled with each other, wherein a first end of the primary side winding acquires a line voltage, and a second end of the primary side winding is coupled with the primary side switch; wherein the line voltage is sensed by a current signal on the auxiliary winding and a compensation signal is generated based on the current signal.
In one embodiment, the current reference signal is generated based on a voltage value on the auxiliary winding.
The isolated voltage conversion system, the primary side control circuit thereof and the line voltage feedforward compensation method can be used for effectively reducing or eliminating ripples of output voltage in the isolated voltage conversion circuit of quasi-resonance control, particularly ripples under the condition of low voltage and heavy load.
Drawings
FIG. 1 illustrates an isolated voltage conversion system according to an embodiment of the present invention;
FIG. 2 illustrates a flyback voltage conversion system according to an embodiment of the present invention;
FIG. 3 shows a signal waveform diagram corresponding to the circuit of FIG. 2, in accordance with an embodiment of the present invention;
FIG. 4 shows a second control circuit schematic according to an embodiment of the invention;
FIG. 5 shows a second control circuit schematic according to another embodiment of the invention;
FIG. 6 shows a schematic diagram of a primary side control circuit according to an embodiment of the invention;
FIG. 7 shows a waveform diagram according to an embodiment of the invention;
FIG. 8 illustrates a compensated current reference signal diagram according to an embodiment of the present invention;
FIG. 9 shows a schematic diagram of a waveform of a compensation signal Vcomp according to an embodiment of the invention;
fig. 10 is a flow chart illustrating a line voltage feedforward compensation method for an isolated voltage converter circuit according to an embodiment of the present invention.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
The description in this section is for several exemplary embodiments only, and the present invention is not limited only to the scope of the embodiments described. Combinations of different embodiments, and substitutions of features from different embodiments, or similar prior art means may be substituted for or substituted for features of the embodiments shown and described.
The term "coupled" or "connected" in this specification includes both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as a conductor, wherein the electrically conductive medium may contain parasitic inductance or parasitic capacitance, or through an intermediate circuit or component as described in the embodiments in the specification; indirect connections may also include connections through other active or passive devices that perform the same or similar function, such as connections through switches, signal amplification circuits, follower circuits, and so on.
FIG. 1 illustrates an isolated voltage conversion system according to an embodiment of the present invention. The isolated voltage conversion system comprises an isolated voltage conversion circuit 100 and a primary side control circuit 10, wherein the primary side control circuit 10 controls a primary side switch Q in the isolated voltage conversion circuit 100. The primary side switch is the main power switch of the isolated voltage conversion circuit 100. The input end of the isolated voltage conversion circuit 100 receives a line voltage Vline, the output end of the isolated voltage conversion circuit 100 provides an output voltage Vout, the isolated voltage conversion circuit 100 converts the line voltage Vline into the output voltage Vout under the switching action of the primary side switch Q, and the output voltage Vout is used for driving a load. Preferably, the line voltage Vline is a post-bridge voltage signal obtained by rectifying the commercial power alternating current through a rectifying circuit and filtering the rectified commercial power alternating current through an input capacitor. The primary side control circuit 10 includes a first control circuit 11, a second control circuit 12, and a logic driving circuit 13. The first control circuit 11 provides a first control signal C1 for controlling the primary side switch Q to switch from the first state to the second state when the quasi-resonant state is satisfied, and the second control circuit 12 provides a second control signal C2 for switching the primary side switch Q from the second state to the first state when the primary side current Ip rises to the reference threshold Iref. Preferably, the first state is an off state and the second state is an on state. In one embodiment, the first control circuit 11 turns on the primary side switch Q when detecting that the voltage difference between the two ends of the primary side switch Q drops to the valley position, so as to implement zero voltage conduction of the primary side switch Q and improve the system efficiency, and when the voltage difference between the two ends of the primary side switch Q drops to the valley position so as to satisfy the quasi-resonance state, such control may be referred to as quasi-resonance control. Two input ends of the logic driving circuit 13 receive a first control signal C1 and a second control signal C2, respectively, and an output end of the logic driving circuit 13 is coupled to the control end of the primary side switch Q for controlling the on/off of the primary side switch Q through a control signal CTL. In one embodiment, logic drive circuit 13 is shown as logic drive circuit 65 in FIG. 6. Preferably, the isolated voltage converter circuit comprises a flyback voltage converter circuit, as shown in fig. 2. However, the isolated voltage converter circuit may have a different structure from the flyback voltage converter circuit shown in fig. 2, such as a forward voltage converter circuit. The second control circuit 12 includes a line voltage compensation circuit 121, where the line voltage compensation circuit 121 is configured to obtain a line voltage signal representing a line voltage Vline at an input end of the isolated voltage conversion circuit 100, generate a feed-forward compensation signal Vcomp of the line voltage based on the line voltage signal, and adjust an amplitude of a primary current based on a ripple of the line voltage Vline. The second control circuit 12 compensates the reference threshold Iref with the compensation signal Vcomp. The primary side current reference threshold Iref is controlled by the post-bridge line voltage feed-forward compensation for eliminating or reducing the fluctuation of the output voltage Vout caused by the fluctuation of the line voltage Vline.
The compensation of the reference threshold Iref by the compensation signal Vcomp generated based on the line voltage can be realized by using the compensation signal for compensating the current sampling signal or by using the compensation signal for compensating the current reference signal, wherein the primary side switch is turned off when the current sampling signal representing the current flowing through the primary side switch of the isolated voltage conversion circuit reaches the current reference signal. The compensation method may specifically comprise adding the compensation signal Vcomp to a current reference signal characterizing the current peak or subtracting the compensation signal Vcomp from a current sample signal of the primary circuit, see the embodiment of fig. 4 or 5.
Fig. 2 illustrates a flyback voltage conversion system according to an embodiment of the present invention. The flyback voltage conversion system includes a rectification circuit 21, a flyback voltage conversion circuit, and a primary side control circuit 20. The rectifying circuit 21 is used to rectify an ac power source Vac into a dc power source. Preferably, the input end of the rectifying circuit 21 is coupled to the ac mains Vac, and the output end thereof provides the line voltage Vline. The input terminal of the flyback voltage converter circuit is coupled to the output terminal of the rectifier circuit 21, and the output terminal of the flyback voltage converter circuit provides an output voltage Vout for driving the load RL. The flyback voltage conversion circuit comprises a primary winding Lp, a primary switch Q, a sampling resistor Rcs, a secondary winding Ls, a secondary rectifier tube D and an auxiliary winding Lm. A first end of the primary winding Lp is coupled to an output end of the rectifier circuit 21 for receiving the line voltage Vline. A first end of the primary side switch Q is coupled to a second end of the primary side winding Lp, a second end of the primary side switch Q is coupled to a first end of a sampling resistor Rcs for generating a current sampling signal Vcs reflecting a current (primary side current Ip) flowing through the primary side switch Q, a second end of the sampling resistor Rcs is coupled to a primary side ground GND, and a control end of the primary side switch Q is coupled to an output end of the primary side control circuit 20. The primary winding Lp, the secondary winding Ls and the auxiliary winding Lm of the transformer T are coupled to each other, and the secondary winding Ls is coupled to the secondary rectifier tube D and provides an output voltage Vout. The auxiliary winding Lm is coupled to the primary winding Lp for providing a feedback signal FB indicative of the variation of the output voltage Vout. The feedback control of the feedback signal of the output voltage Vout obtained by non-optical coupling transmission modes such as an auxiliary winding Lm is primary side feedback control. A first input terminal of the primary side control circuit 20 is coupled to a second terminal of the primary side switch Q for obtaining a current sampling signal Vcs representing a primary side current Ip, a second input terminal of the primary side control circuit 20 is coupled to the auxiliary winding Lm for obtaining a feedback signal FB, and an output terminal of the primary side control circuit 20 provides a control signal CTL and is coupled to a control terminal of the primary side switch Q for driving the primary side switch Q. In one embodiment, the primary switch Q is turned on when the voltage at the first terminal of the primary switch Q drops to the valley. Preferably, the primary side switch Q comprises a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), wherein the first terminal of the primary side switch Q is its drain terminal, the second terminal of the primary side switch Q is its source terminal, and the control terminal of the primary side switch Q is its gate terminal. The primary side switch Q can also be other types of power switching tubes.
In one embodiment, the primary side control circuit that controls the isolated voltage converting circuit using quasi-resonance control and primary side feedback control switches off the primary side switch Q when a current sampling signal Vcs representing a current Ip flowing through the primary side switch of the isolated voltage converting circuit reaches a current reference signal, wherein the primary side control circuit 20 further generates a compensation signal based on the line voltage Vline and uses the compensation signal to compensate for an amplitude of the current sampling signal Vcs or the current reference signal. Preferably, the current sampling signal Vcs increases with an increase in the primary current Ip, and when the current sampling signal Vcs rises to be greater than the current reference signal Vref, the primary switch Q is controlled to be switched from the on state to the off state. According to the common knowledge in the art, the current sampling signal can also be controlled to fall along with the rise of the primary current, for example, a negative voltage can be controlled, and the primary switch can be turned off when the current sampling signal falls to be smaller than the current reference signal, so that the same control is realized.
In another embodiment, the primary side switch Q may also be part of the primary side control circuit. The illustrated primary side switch Q and the primary side control circuit 20 may be packaged in the same electronic package or fabricated on the same semiconductor chip.
The isolated voltage converting circuit is not limited to the embodiment shown in fig. 2. The isolated voltage converting circuit may have other topologies or have different or additional connection relationships, for example, the primary circuit of the isolated voltage converting circuit further includes a leakage inductance feedback circuit, and the secondary rectifier D is located between the different-name end of the secondary winding and the secondary ground.
Fig. 3 shows a signal waveform diagram corresponding to the circuit in fig. 2 according to an embodiment of the invention. Fig. 3 shows a primary current Ip flowing through the primary switch Q, a secondary current Is flowing through the secondary winding Ls, a control signal CTL and a feedback signal FB controlling the primary switch Q, respectively. At time t1, the primary current Ip rises to the reference threshold Iref, the control signal CTL changes from a high level state to a low level state for switching the primary switch Q from a conducting state to a switching off state, the primary energy Is transmitted to the secondary, and the secondary current Is at a peak value on the secondary winding Ls and starts to slowly decrease after supplying energy to the output capacitor Co or the load. At this point the feedback signal FB on the auxiliary winding Lm begins to rise to a high value, which reflects the output voltage Vout and the line voltage Vline. At time t2, the system satisfies a quasi-resonance state, and if it Is detected that the secondary side current Is decreases to a zero value, or the terminal voltage of the primary side switch Q decreases to a preset valley value or a zero value, the system Is configured to set the control signal CTL from a low level to a high level, and Is configured to switch the primary side switch Q from an off state to an on state, so that the primary side current Ip starts to increase, the primary side circuit starts to accumulate energy, and the feedback signal FB decreases. The detection of the quasi-resonant state may employ any existing or suitable zero voltage detection technique or degaussing detection technique. Wherein the feedback signal FB reflects the change of the line voltage Vline, which depends on the line voltage Vline, the winding turn ratio of the primary winding Lp and the auxiliary winding Lm, and the voltage dividing resistors Rup and Rdown. Therefore, by generating the compensation signal by the feedback signal and compensating the reference threshold Iref, the ripple in the output voltage Vout caused by the ripple of the line voltage Vline can be eliminated or effectively reduced.
FIG. 4 shows a second control circuit schematic according to an embodiment of the invention. The second control circuit includes a line voltage compensation circuit 41, a current reference signal generation circuit 42, an addition circuit 43, and a comparison circuit 44. Wherein the current reference signal generating circuit 42 generates a current reference signal Vref. In one embodiment, the current reference signal Vref is also generated based on the feedback signal FB, but its control loop includes a low frequency filtering block, which is a slow-reacting loop. The adding circuit 43 has a first input terminal and a second input terminal respectively coupled to the output terminal of the line voltage compensation circuit 41 and the output terminal of the current reference signal generating circuit 42, and the adding circuit 43 generates a compensated current reference signal Vref-comp based on the current reference signal Vref and the compensation signal Vcomp, wherein the compensated current reference signal Vref-comp is Vref + Vcomp. The comparison circuit 44 has a first input terminal, a second input terminal, and an output terminal, the first input terminal of the comparison circuit is coupled to the output terminal of the addition circuit 43, the second input terminal of the comparison circuit 44 is coupled to the current sampling resistor for obtaining a current sampling signal Vcs, the comparison circuit 44 compares the current sampling signal Vcs representing the current Ip flowing through the primary side switch with the compensated current reference signal Vref-comp, and provides a second control signal C2 based on the comparison result, and when the current sampling signal Vcs is greater than the compensated current reference signal Vref-comp, the second control signal C2 is configured to switch the primary side switch Q from an on state to an off state. According to the embodiment shown in fig. 2, the current sampling signal Vcs is Ip Rcs.
Fig. 5 shows a schematic diagram of a second control circuit according to another embodiment of the invention. The second control circuit includes a line voltage compensation circuit 51, a current reference signal generation circuit 52, a subtraction circuit 53, and a comparison circuit 54. Wherein the current reference signal generating circuit 52 generates a current reference signal Vref. In one embodiment, the current reference signal Vref is also generated based on the feedback signal FB, but its control loop includes a low frequency filtering block, which is a slow-reacting loop. The subtraction circuit 53 has a first input terminal and a second input terminal, and is respectively coupled to the output terminal of the line voltage compensation circuit 51 and the output terminal of the current sampling circuit for obtaining a current sampling signal Vcs of the primary current Ip, and the subtraction circuit 53 generates a compensated current sampling signal Vcs-comp based on a difference between the current sampling signal Vcs and the compensation signal Vcomp, where the compensated current sampling signal Vcs-comp is Vcs-Vcomp. The comparison circuit 54 has a first input terminal, a second input terminal and an output terminal, the first input terminal of the comparison circuit 54 is coupled to the output terminal of the subtraction circuit 53 for obtaining the compensated current sampling signal Vcs-comp, the second input terminal of the comparison circuit 54 is coupled to the output terminal of the current reference signal generating circuit 52 for receiving the current reference signal Vref, the comparison circuit 54 compares the compensated current sampling signal Vcs-comp with the current reference signal Vref and provides a second control signal C2 based on the comparison result, and when the compensated current sampling signal Vcs-comp is greater than the current reference signal Vref, the second control signal C2 is used for switching the primary side switch from the on state to the off state.
Fig. 6 shows a schematic diagram of a primary side control circuit according to an embodiment of the invention. The primary side control circuit comprises a quasi-resonant primary side control circuit 61, a current reference signal generating circuit 62, a line voltage compensating circuit 63, a compensating comparison circuit 64 and a logic driving circuit 65. The input terminals of the quasi-resonant primary side control circuit 61, the current reference signal generating circuit 62 and the line voltage compensating circuit 63 are coupled to the auxiliary winding Lm for receiving the feedback signal FB. Wherein the quasi-resonant primary control circuit 61 forms all or part of the first control circuit 11 shown in fig. 1 for generating the first control signal C1. The current reference signal generating circuit 62, the line voltage compensating circuit 63 and the compensation comparing circuit 64 form all or part of the second control circuit 12 shown in fig. 1 for generating the second control signal C2. The logic driving circuit 65 may include a flip-flop circuit 651 and a driving circuit 652 for generating the control signal CTL according to the first control signal C1 and the second control signal C2.
In one embodiment, the quasi-resonant primary side control circuit 61 includes a demagnetization detection circuit, and the demagnetization detection circuit obtains the time when the voltage at the first terminal of the primary side switch first drops to the valley bottom by detecting the change of the feedback signal, so as to obtain the demagnetization time and turn on the primary side switch at the time. Referring to fig. 3, in one embodiment, when the falling slope of the feedback signal FB exceeds a predetermined value, which indicates that the voltage at the primary switch terminal falls to the valley position, the first control signal C1 is switched from an inactive state (e.g., low level) to an active state (e.g., high level) for turning on the primary switch.
The current reference signal generation circuit 62 generates a current reference signal Vref. In the illustrated embodiment, the current reference signal Vref is generated based on the feedback signal FB. The current reference signal generating circuit 62 may include a sample-and-hold circuit 621, an error amplifying circuit 622, a low-pass filtering circuit 623, and an amplitude modulation circuit 624. Wherein the input terminal of the sample-and-hold circuit 621 is coupled to the auxiliary winding Lm for obtaining the feedback signal FB, and the sample-and-hold circuit 621 performs sample-and-hold on the feedback signal FB and provides a sample-and-hold signal at the output terminal of the sample-and-hold circuit 621. The sample-and-hold signal reflects the value of the feedback signal FB. The input terminal of the error amplifying circuit 622 is coupled to the output terminal of the sample-and-hold circuit 621, the output terminal of the error amplifying circuit 622 is coupled to the input terminal of the low-pass filter circuit 623, the output terminal of the low-pass filter circuit 623 is coupled to the input terminal of the amplitude modulation circuit 624, the output terminal of the amplitude modulation circuit 624 provides a current reference signal Vref, the current reference signal is generated by error amplifying and low-pass filtering the sample-and-hold signal of the feedback signal, and is used for controlling the low-pass signal component of the output voltage. The current reference signal generating circuit 62 may have other configurations, may directly generate the fixed current reference signal, or may generate the fixed current reference signal using other circuit configurations. The current reference signal generating circuit 62 is a slow loop, and cannot perform fast feedback on the output voltage, and for example, the wireless voltage compensating circuit 63 is prone to cause ripple of the output voltage due to ripple of the line voltage.
In the embodiment shown in fig. 6, the line voltage compensation circuit 63 includes a current control voltage source, an input terminal of the current control voltage source 63 is coupled to the auxiliary winding Lm of the isolated voltage converting circuit, see the feedback node FB shown in fig. 2, and an output terminal of the current control voltage source 63 provides the compensation signal Vcomp. The current control voltage source 63 includes a current mirror 631, a current conversion circuit 632, and a current-voltage conversion circuit 633. The input end of the current mirror 631 is coupled to the feedback node FB, and the output end of the current mirror 631 provides a line voltage current signal Iline proportional to a line voltage Vline, where the current signal Iline/(K1 Npa Rup), where Npa is a winding turn ratio of the primary winding Lp and the auxiliary winding Lm, Rup is an upper resistance value of the FB divider resistor, and K is a multiple of the current mirror. The current transformation circuit 632 is coupled to the current mirror 631, the current transformation circuit 632 includes a reference current source I0, and the current transformation circuit 632 obtains a difference current signal I0-Iline between a reference current I0 and a line voltage current signal Iline, wherein I0 represents a value of a target line voltage. The input terminal of the current-voltage conversion circuit 633 is coupled to the output terminal of the current transformation circuit 632 and the resistor R0, the output terminal of the current-voltage conversion circuit 633 provides a voltage signal proportional to the difference current signal as a compensation signal Vcomp, (I0-Iline) × K2 ═ K2 (I0-Vline/(K1 × Npa) × Rup)), where K2 is a product of the resistances R0 and R1 and a voltage-dividing resistance ratio K3 of R2. As the line voltage increases, the compensation signal Vcomp decreases. The current-voltage conversion circuit 633 may further receive an upper limit current reference signal Vref2, and when the product of the difference current signal and the resistance (I0-Iline) × R0 is greater than the upper limit current reference signal Vref2, the compensation signal Vcomp is limited to Vref × K3 by the upper limit current reference signal, i.e., the compensation signal Vcomp is limited to min ((I0-Iline) × R0, Vref2) × K3.
The line voltage compensation circuit may have other configurations. In one embodiment, the input terminal of the line voltage compensation circuit is directly coupled to the output terminal of the rectification circuit through the resistor voltage division circuit, and the output terminal of the line voltage compensation circuit provides the line voltage compensation signal.
The compensation comparator 64 has three inputs including a first input receiving a current sampling signal Vcs indicative of a current flowing through the primary switch, a second input receiving a current reference signal Vref, a third input receiving a compensation signal Vcomp, and an output providing a second control signal C2. The compensation comparison circuit 64 determines whether Vcs-Vref-Vcomp is greater than zero, and outputs the second control signal C2 in an active state if the Vcs-Vref-Vcomp is greater than zero. The second control signal C2, when active, is used to turn the primary switch Q off.
The logic driving circuit 65 includes a trigger circuit 651 and a driving circuit 652, a first input terminal (a set terminal) of the trigger circuit 651 is coupled to the output terminal of the first control circuit 61 for receiving the first control signal C1, a second input terminal of the trigger circuit 652 is coupled to the output terminal of the second control circuit (62, 63, 64), and an output terminal of the trigger circuit 652 is coupled to the control terminal of the primary switch Q through the driving circuit 652. The trigger circuit 651 outputs a pulse width modulated signal PWM based on the first control signal C1 and the second control signal C2, which is amplified by the drive circuit 652 to provide a control signal CTL adapted to drive the primary side switch Q. In one embodiment, the trigger circuit 651 is set when the first control signal C1 transitions from a low level to a high level and the PWM signal transitions from a low level to a high level for turning on the primary side switch Q, and is reset when the second control signal C2 transitions from a low level to a high level and the PWM signal transitions from a high level to a low level for turning off the primary side switch Q.
Fig. 7 shows a waveform diagram according to an embodiment of the invention. The signals from top to bottom are respectively a line voltage Vline, a current sampling signal Vcs of primary current, a current reference signal Vref, a compensation signal Vcomp, a compensated reference voltage Vref-comp and an output voltage Vout. The line voltage Vline can be a bridge signal of commercial power alternating current after rectification and filtering, and the shape of the line voltage Vline is a direct current steamed bread wave shape. In order to equalize the output energy, the envelope of the current sampling signal Vcs also has an inverted steamed bread component. The compensation signal Vcomp is generated based on the line voltage Vline and rises as the line voltage Vline falls. And after the current reference signal Vref is compensated by adopting the compensation signal Vcomp, the compensated current reference signal Vref-comp is the sum of the original current reference signal Vref and the compensation signal Vcomp. By such control, the envelope in the Vcs signal is provided by the compensation signal Vcomp without the need for the current reference signal Vref, i.e., without the need for the output voltage Vout to fluctuate, so that the output voltage Vout can be kept in a straight line, i.e., the ripple in the output voltage is eliminated or reduced.
The embodiment of fig. 6 achieves a reduction in output voltage ripple based on the peak value of the post-bridge voltage, i.e., the line voltage Vline feed forward compensation Vcs signal. The ripple information of the line voltage Vline is extracted, the amplitude of the signal Vcs is directly adjusted based on the ripple of the line voltage Vline without control processing such as sampling of a feedback signal FB and subsequent low-pass filtering, and therefore the adjustment of the amplitude of the signal Vcs is not performed by a slow loop in the prior art, but is directly performed by a fast feedforward compensation loop for extracting the ripple information of the line voltage Vline, so that effective compensation of the line voltage ripple is achieved, and the ripple of the output voltage Vout is reduced.
In one embodiment, the output voltage Vout is almost completely free of line ripple using the fast-reacting feedforward compensation loop described above. The energy difference generated by the line voltage Vline ripple is completely compensated by the feedforward compensation loop (including the line voltage compensation circuit 63 and the compensation comparison circuit 64).
FIG. 8 illustrates a compensated current reference signal diagram according to an embodiment of the present invention. The horizontal axis represents the depth of the load, and the depth is changed from light load to medium load and then to heavy load from left to right. The ordinate represents the value of the compensated current reference signal Vref-comp. The solid line 81 represents the compensated current reference signal Vref-comp and the dashed line 82 represents the uncompensated current reference signal Vref, wherein the solid line 81 and the dashed line 82 coincide during light and medium load phases. That is, when the system is lightly loaded, the compensation signal Vcomp is close to zero. The compensated current reference signal Vref-comp is shifted only during a heavy load, i.e. the compensation of the current reference signal Vref by the compensation signal Vcomp is performed only during a heavy load.
Fig. 9 shows a schematic diagram of a waveform of the compensation signal Vcomp according to an embodiment of the present invention. Where the abscissa represents the feedback signal, which reflects the line voltage level. The ordinate represents the level of the compensation signal Vcomp. The compensation effect on the reference threshold is more obvious when the line voltage is lower and the absolute value of the compensation signal Vcomp is larger, and the compensation effect on the reference threshold is reduced when the line voltage is lower and the absolute value of the compensation signal Vcomp is smaller.
As can be seen from fig. 8 and 9, the primary side control circuit has a large compensation effect on the line voltage when the low input voltage is heavily loaded, and has a low compensation effect when the input voltage is lightly loaded or high, so that the output voltage ripple caused by the ripple of the line voltage under the condition of low input and heavy load can be eliminated or reduced.
Fig. 10 is a flow chart illustrating a line voltage feedforward compensation method for an isolated voltage converter circuit according to an embodiment of the present invention. In step 1001, in normal operation, it is detected whether the isolated voltage conversion circuit satisfies a quasi-resonance state, where the quasi-resonance state is a condition that the voltage of the primary side switch terminal is a valley value or the secondary side current of the isolated voltage conversion circuit is reduced to a zero value. The isolated voltage converter circuit may be a flyback voltage converter circuit, but is not limited to a flyback voltage converter circuit. In one embodiment, the isolated voltage conversion circuit includes a primary switch Q, and a primary winding Lp, a secondary winding Is, and an auxiliary winding Lm coupled to each other, where a first end of the primary winding Lp obtains a line voltage Vline, a second end of the primary winding Lp Is coupled to the primary switch Q, and the line voltage may be a signal obtained by rectifying and filtering a commercial power alternating current. The detection of the quasi-resonant state of the isolated voltage converting circuit may be determined by detecting whether the voltage across the auxiliary winding of the isolated voltage converting circuit falls within a predetermined range, or any other suitable switch zero voltage detection technique or demagnetization detection technique may be employed. When the isolated voltage conversion circuit is detected to meet the quasi-resonance state, step 1002 is entered, and the primary side switch Q is switched from the first state to the second state. Preferably, the first state is an off state and the second state is an on state. In step 1003, it is detected whether the primary side current Ip in the primary side circuit of the isolated voltage converting circuit rises to the reference threshold Iref. When the primary side current Ip is detected to rise to the reference threshold value Iref, step 1004 is entered, and the primary side switch Q is switched from the second state to the first state, where the reference threshold value Iref represents the peak value of the primary side current Ip. Wherein the method further comprises, at step 1005: the primary side current peak value Iref is compensated based on the ripple of the line voltage Vline at the input end of the isolated voltage conversion circuit. The method for compensating the peak value of the primary side current based on the ripple of the line voltage Vline at the input end of the isolated voltage conversion circuit can comprise the following steps: the compensation method comprises the steps of generating a compensation signal Vcomp based on a line voltage Vline, generating a current reference signal Vref based on an output voltage Vout of an isolation type voltage conversion circuit, obtaining a current sampling signal Vcs representing a current flowing through a primary side switch Q, and adding the compensation signal Vcomp and the current reference signal Vref or subtracting the compensation signal Vcomp from the current sampling signal Vcs to realize compensation of a primary side current peak value. Specifically, the ripple based on the line voltage Vline generates the compensation signal Vcomp by directly coupling to the output terminal of the rectifier circuit to detect the line voltage Vline, or by detecting the line voltage with the current signal on the auxiliary winding Lm shown in fig. 2 and 6 and by using the current control voltage source 63 to generate the compensation signal Vcomp based on the current signal. Specifically, the current reference signal Vref is generated based on the output voltage Vout of the isolated voltage conversion circuit, and feedback information of the output voltage Vout is obtained through the auxiliary winding Lm of the isolated voltage conversion circuit, and the current reference signal Vref is generated based on the voltage value of the auxiliary winding Lm, which can be referred to in the embodiment of the current reference signal generation circuit 62 shown in fig. 6. The current sampling signal can be obtained by detecting the voltage on a current sampling resistor Rcs which is connected with the primary side switch Q in series. The compensation of the reference threshold by adding the compensation signal to the current reference signal or subtracting the compensation signal from the current sample signal can be implemented by the embodiments of fig. 4 and 5, or by the compensation comparison circuit shown in fig. 6.
Those skilled in the art should understand that the logic controls such as "high" and "low", "set" and "reset", "and gate" and "or gate", "non-inverting input" and "inverting input" in the logic controls referred to in the specification or the drawings may be exchanged or changed, and the subsequent logic controls may be adjusted to achieve the same functions or purposes as the above-mentioned embodiments.
The description and applications of the invention herein are illustrative and are not intended to limit the scope of the invention to the embodiments described above. The descriptions related to the effects or advantages in the specification may not be reflected in practical experimental examples due to uncertainty of specific condition parameters or influence of other factors, and the descriptions related to the effects or advantages are not used for limiting the scope of the invention. Variations and modifications of the embodiments disclosed herein are possible, and alternative and equivalent various components of the embodiments will be apparent to those skilled 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 components, materials, and parts, 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 (19)
1. A primary side control circuit for an isolated voltage conversion circuit, comprising:
the first control circuit provides a first control signal for controlling the primary side switch to be switched from a first state to a second state when the isolated voltage conversion circuit meets the quasi-resonance state;
the second control circuit provides a second control signal for switching the primary side switch from the second state to the first state when the primary side current rises to the reference threshold; wherein
The second control circuit comprises a line voltage compensation circuit, the line voltage compensation circuit is used for acquiring a line voltage signal representing the line voltage at the input end of the isolated voltage conversion circuit and generating a compensation signal based on the line voltage signal, and the second control circuit adopts the compensation signal to compensate the reference threshold value.
2. The primary side control circuit of claim 1 wherein the second control circuit further comprises:
a current reference signal generating circuit that generates a current reference signal;
an addition circuit that generates a compensated current reference signal based on the current reference signal and the compensation signal; and
and the comparison circuit is used for comparing a current sampling signal representing the current flowing through the primary side switch with the compensated current reference signal and providing a second control signal for switching the primary side switch from the on state to the off state based on the comparison result.
3. The primary side control circuit of claim 1 wherein the second control circuit further comprises:
a current reference signal generating circuit that generates a current reference signal;
a subtraction circuit that generates a compensated current sampling signal based on a difference between a current sampling signal representing a current flowing through the primary side switch and the compensation signal; and
and the comparison circuit is used for comparing the compensated current sampling signal with the current reference signal and providing a second control signal based on the comparison result so as to switch the primary side switch from the on state to the off state.
4. The primary side control circuit of claim 1 wherein the second control circuit further comprises:
a current reference signal generating circuit that generates a current reference signal; and
the compensation comparison circuit is provided with a first input end, a second input end, a third input end and an output end, wherein the first input end receives a current sampling signal representing current flowing through the primary side switch, the second input end receives a current reference signal, the third input end receives a compensation signal, and the output end of the compensation comparison circuit provides a second control signal for switching off the primary side switch.
5. The primary control circuit of claim 1, wherein the line voltage compensation circuit comprises a current controlled voltage source having an input coupled to the auxiliary winding of the isolated voltage converter circuit and an output providing the compensation signal.
6. The primary control circuit of claim 5 wherein the current controlled voltage source comprises:
the current mirror acquires a line voltage current signal which is in direct proportion to the line voltage;
the current conversion circuit is used for acquiring a difference current signal between the reference current and the line voltage current signal; and
and the input end of the current-voltage conversion circuit is coupled with the output end of the current conversion circuit and the resistor, and the output end of the current-voltage conversion circuit provides a voltage signal which is proportional to the difference current signal as a compensation signal.
7. The primary control circuit of claim 6 wherein the current-to-voltage conversion circuit further receives an upper current reference signal, the compensation signal being limited by the upper current reference signal when the product of the difference current signal and the resistance is greater than the upper current reference signal.
8. The primary side control circuit of claim 1, wherein the isolated voltage converter circuit comprises a flyback voltage converter circuit, the primary side switch has a first end, a second end, and a control end, the first end of the primary side switch is coupled to the second end of the primary winding of the isolated voltage converter circuit, the first end of the primary winding receives a line voltage, the second end of the primary side switch is coupled to a sampling resistor for providing a current sampling signal reflecting the primary side current, the other end of the sampling resistor is coupled to a primary side ground, the control end of the primary side switch is coupled to an output end of the primary side control circuit, and wherein the first control circuit turns on the primary side switch when the voltage at the first end of the primary side switch drops to a valley bottom.
9. The primary side control circuit of claim 1 further comprising a trigger circuit having a first input coupled to the output of the first control circuit, a second input coupled to the output of the second control circuit, and an output coupled to the control terminal of the primary side switch.
10. The primary side control circuit of claim 1 wherein the first state is an off state and the second state is an on state.
11. The primary side control circuit of any of claims 2 to 4 wherein the current reference signal generating circuit comprises:
the input end of the sampling and holding circuit is coupled with the auxiliary winding of the isolated voltage conversion circuit and used for acquiring a feedback signal, and the output end of the sampling and holding circuit provides a sampling and holding signal for sampling and holding the feedback signal;
the input end of the error amplifying circuit is coupled with the output end of the sampling and holding circuit;
the input end of the low-pass filter circuit is coupled with the output end of the error amplifying circuit; and
and the input end of the amplitude modulation circuit is coupled with the output end of the low-pass filter circuit, and the output end of the amplitude modulation circuit provides a current reference signal.
12. An isolated voltage conversion system comprising:
the input end of the rectification circuit is coupled with a commercial power alternating current power supply, and the output end of the rectification circuit provides line voltage;
the input end of the isolated voltage conversion circuit is coupled with the output end of the rectifying circuit, and the output end of the isolated voltage conversion circuit provides output voltage for driving a load; and
the primary side control circuit of any of claims 1-10.
13. The isolated voltage conversion system of claim 12, wherein the isolated voltage conversion circuit comprises:
a primary winding, the first end of which is coupled with the output end of the rectifying circuit;
a first end of the primary side switch is coupled with a second end of the primary side winding;
a first end of the sampling resistor is coupled with a second end of the primary side switch, and a second end of the sampling resistor is coupled with a primary side ground;
the secondary winding is coupled with the primary winding and is coupled with the secondary rectifying tube and provides output voltage; and
the auxiliary winding is coupled with the primary winding and used for providing a feedback signal;
the first input end of the primary side control circuit is coupled with the second end of the primary side switch, the second input end of the primary side control circuit is coupled with the auxiliary winding, and the output end of the primary side control circuit is coupled with the control end of the primary side switch.
14. A primary side control circuit for an isolation type voltage conversion circuit is provided, wherein the input end of the isolation type voltage conversion circuit receives line voltage, the output end of the isolation type voltage conversion circuit is coupled with a load, the isolation type voltage conversion circuit adopts quasi-resonance control and primary side feedback control, the primary side control circuit is used for switching off a primary side switch when a current sampling signal representing current flowing through the primary side switch of the isolation type voltage conversion circuit reaches a current reference signal, and the primary side control circuit further generates a compensation signal based on the line voltage and uses the compensation signal for compensating the current sampling signal or the current reference signal.
15. The primary control circuit of claim 14 wherein the isolated voltage conversion circuit comprises a primary winding, a secondary winding, and an auxiliary winding, the primary control circuit comprising:
the quasi-resonance primary side control circuit is coupled with the auxiliary winding and controls the conduction of the primary side switch when the feedback voltage on the auxiliary winding is at the valley bottom position;
the current reference signal generating circuit is coupled with the auxiliary winding and generates a current reference signal based on the feedback voltage; and
and the line voltage compensation circuit is coupled with the auxiliary winding, acquires a voltage signal representing the line voltage based on the current signal on the auxiliary winding and generates a compensation signal.
16. A line voltage feedforward compensation method for an isolated voltage conversion circuit includes:
when the isolated voltage conversion circuit meets the quasi-resonance state, the primary side switch is switched from a first state to a second state;
when the primary side current rises to a reference threshold value, the primary side switch is switched from a second state to a first state; and
and compensating the primary side current peak value according to the ripple wave of the line voltage at the input end of the isolated voltage conversion circuit.
17. The method of claim 16, wherein compensating for primary side current peaks based on a ripple of the line voltage at the input of the isolated voltage translation circuit comprises:
generating a compensation signal based on the ripple of the line voltage;
generating a current reference signal based on an output voltage of the isolated voltage conversion circuit;
acquiring a current sampling signal representing current flowing through a primary side switch;
and adding the compensation signal and the current reference signal or subtracting the compensation signal from the current sampling signal to realize the compensation of the primary current peak value.
18. The method of claim 16, wherein the isolated voltage converting circuit comprises a primary switch and a primary winding, a secondary winding, and an auxiliary winding coupled to each other, wherein a first end of the primary winding obtains the line voltage and a second end of the primary winding is coupled to the primary switch; wherein the line voltage is sensed by a current signal on the auxiliary winding and a compensation signal is generated based on the current signal.
19. The method of claim 16, wherein the current reference signal is generated based on a voltage value on the auxiliary winding.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114006538A (en) * | 2021-11-17 | 2022-02-01 | 深圳市必易微电子股份有限公司 | Flyback converter control circuit and control method and flyback converter |
| CN114244155A (en) * | 2021-12-17 | 2022-03-25 | 深圳市必易微电子股份有限公司 | Double-loop control circuit for power conversion circuit and high-precision constant current control method |
Citations (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101582631A (en) * | 2009-06-24 | 2009-11-18 | 北京中星微电子有限公司 | Feedforward compensated oscillator |
| CN104617792A (en) * | 2014-12-24 | 2015-05-13 | 昂宝电子（上海）有限公司 | System and method for adjusting voltage of power conversion system for primary side adjustment |
| CN104993704A (en) * | 2015-07-17 | 2015-10-21 | 东南大学 | Digital constant current controller based on flyback primary side feedback |
| CN105048814A (en) * | 2014-04-24 | 2015-11-11 | 立锜科技股份有限公司 | Flyback power converter and control circuit and control method thereof |
| US20160172981A1 (en) * | 2014-12-16 | 2016-06-16 | Stmicroelectronics S.R.L. | Control method and device employing primary side regulation in a quasi-resonant ac/dc flyback converter |
| US20160261199A1 (en) * | 2015-03-06 | 2016-09-08 | Stmicroelectronics S.R.L. | Control method and device for quasi-resonant high-power-factor flyback converter |
| US20160276936A1 (en) * | 2015-03-18 | 2016-09-22 | Stmicroelectronics S.R.L. | Method and device for high-power-factor flyback converter |
| US20160359419A1 (en) * | 2014-12-07 | 2016-12-08 | Alpha And Omega Semiconductor (Cayman) Ltd. | Voltage converter |
| US20170207713A1 (en) * | 2016-01-20 | 2017-07-20 | Acbel Polytech Inc. | Feed forward controlling circuit and method for voltage ripple restraint |
| CN107026563A (en) * | 2016-02-01 | 2017-08-08 | 康舒科技股份有限公司 | Suppress the feedforward control circuit of voltage ripple |
| CN107612305A (en) * | 2017-11-10 | 2018-01-19 | 王子豪 | The method of preposition quasi- Z sources lifting switch power supply electric work efficiency |
| CN110535343A (en) * | 2018-05-24 | 2019-12-03 | 雅达电子国际有限公司 | Controller and control method and DC-to-dc converter for resonance circuit |
| CN111130319A (en) * | 2020-02-13 | 2020-05-08 | 杭州必易微电子有限公司 | Voltage conversion circuit, primary side control circuit and primary side switch control method |
| CN111327181A (en) * | 2020-03-26 | 2020-06-23 | 杰华特微电子（杭州）有限公司 | Control method and control circuit of multiphase switch circuit and multiphase switch circuit |
| CN111327179A (en) * | 2020-03-18 | 2020-06-23 | 南京矽力微电子技术有限公司 | Control circuit, control method and switching power supply applying control circuit and control method |
| CN111711345A (en) * | 2020-06-23 | 2020-09-25 | 成都芯源系统有限公司 | Driving method, driving circuit and switching power supply thereof |
| CN111884494A (en) * | 2020-07-23 | 2020-11-03 | 成都启臣微电子股份有限公司 | Quasi-resonance valley bottom conduction circuit with compensation function |
| CN112448370A (en) * | 2019-09-04 | 2021-03-05 | 厦门市必易微电子技术有限公司 | Primary side control circuit and control method and isolated power supply conversion circuit |
-
2021
- 2021-03-15 CN CN202110276144.XA patent/CN112953175A/en active Pending
Patent Citations (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101582631A (en) * | 2009-06-24 | 2009-11-18 | 北京中星微电子有限公司 | Feedforward compensated oscillator |
| CN105048814A (en) * | 2014-04-24 | 2015-11-11 | 立锜科技股份有限公司 | Flyback power converter and control circuit and control method thereof |
| US20160359419A1 (en) * | 2014-12-07 | 2016-12-08 | Alpha And Omega Semiconductor (Cayman) Ltd. | Voltage converter |
| US20160172981A1 (en) * | 2014-12-16 | 2016-06-16 | Stmicroelectronics S.R.L. | Control method and device employing primary side regulation in a quasi-resonant ac/dc flyback converter |
| CN104617792A (en) * | 2014-12-24 | 2015-05-13 | 昂宝电子（上海）有限公司 | System and method for adjusting voltage of power conversion system for primary side adjustment |
| US20160261199A1 (en) * | 2015-03-06 | 2016-09-08 | Stmicroelectronics S.R.L. | Control method and device for quasi-resonant high-power-factor flyback converter |
| US20160276936A1 (en) * | 2015-03-18 | 2016-09-22 | Stmicroelectronics S.R.L. | Method and device for high-power-factor flyback converter |
| CN104993704A (en) * | 2015-07-17 | 2015-10-21 | 东南大学 | Digital constant current controller based on flyback primary side feedback |
| US20170207713A1 (en) * | 2016-01-20 | 2017-07-20 | Acbel Polytech Inc. | Feed forward controlling circuit and method for voltage ripple restraint |
| CN107026563A (en) * | 2016-02-01 | 2017-08-08 | 康舒科技股份有限公司 | Suppress the feedforward control circuit of voltage ripple |
| CN107612305A (en) * | 2017-11-10 | 2018-01-19 | 王子豪 | The method of preposition quasi- Z sources lifting switch power supply electric work efficiency |
| CN110535343A (en) * | 2018-05-24 | 2019-12-03 | 雅达电子国际有限公司 | Controller and control method and DC-to-dc converter for resonance circuit |
| CN112448370A (en) * | 2019-09-04 | 2021-03-05 | 厦门市必易微电子技术有限公司 | Primary side control circuit and control method and isolated power supply conversion circuit |
| CN111130319A (en) * | 2020-02-13 | 2020-05-08 | 杭州必易微电子有限公司 | Voltage conversion circuit, primary side control circuit and primary side switch control method |
| CN111327179A (en) * | 2020-03-18 | 2020-06-23 | 南京矽力微电子技术有限公司 | Control circuit, control method and switching power supply applying control circuit and control method |
| CN111327181A (en) * | 2020-03-26 | 2020-06-23 | 杰华特微电子（杭州）有限公司 | Control method and control circuit of multiphase switch circuit and multiphase switch circuit |
| CN111711345A (en) * | 2020-06-23 | 2020-09-25 | 成都芯源系统有限公司 | Driving method, driving circuit and switching power supply thereof |
| CN111884494A (en) * | 2020-07-23 | 2020-11-03 | 成都启臣微电子股份有限公司 | Quasi-resonance valley bottom conduction circuit with compensation function |
Non-Patent Citations (2)
| Title |
|---|
| TING JIANG, HULONG ZENG, JUNMING ZHANG, ZHAOMING QIAN: "A Primary Side Feedforward Control Scheme for Low Power LED Driver Compatible with Triac Dimmer", 2012 TWENTY-SEVENTH ANNUAL IEEE APPLIED POWER ELECTRONICS CONFERENCE AND EXPOSITION (APEC), 9 March 2012 (2012-03-09), pages 963 - 968 * |
| 黄晓敏: "一种基于原边反馈的AC-DC反激式数字恒流控制器的设计", 中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑, no. 03, 15 March 2017 (2017-03-15), pages 042 - 844 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114006538A (en) * | 2021-11-17 | 2022-02-01 | 深圳市必易微电子股份有限公司 | Flyback converter control circuit and control method and flyback converter |
| CN114006538B (en) * | 2021-11-17 | 2024-04-05 | 深圳市必易微电子股份有限公司 | Flyback converter control circuit and control method and flyback converter |
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| CN114244155B (en) * | 2021-12-17 | 2024-03-01 | 深圳市必易微电子股份有限公司 | Double-loop control circuit for power supply conversion circuit and high-precision constant-current control method |
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