CN112055448B - Flyback ripple suppression type electrolytic capacitor-free LED driving power supply - Google Patents
Flyback ripple suppression type electrolytic capacitor-free LED driving power supply Download PDFInfo
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
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- H—ELECTRICITY
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
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Abstract
The invention discloses an LED driving power supply based on Flyback ripple suppression type electrolytic-capacitor-free power supplies, and belongs to the technical field of power generation, power transformation or power distribution. The driving circuit comprises a full-bridge rectification filter circuit, a PFC (power factor correction) conversion circuit, a ripple suppression unit and a control unit. According to the invention, by constructing the isolated single-stage AC-DC converter, the LED driving circuit combining the PFC converter based on the Flyback circuit and the ripple suppression converter based on the full-bridge circuit, the ripple power decoupling is realized, the electrolytic capacitor is avoided, the energy cycle times in the circuit are reduced, the problem of out-of-control output voltage caused by instantaneous input power lower than required output power in a short time is solved, the requirements of no electrolytic capacitor, high power factor and high conversion efficiency are met, the service life of the LED driving power supply is prolonged, and the stability and efficiency of the LED driving power supply are improved.
Description
Technical Field
The invention discloses an LED driving power supply based on Flyback ripple suppression type electrolytic-capacitor-free power supply, relates to the design of an LED lighting driving power supply, and belongs to the technical field of power generation, power transformation or power distribution.
Background
Semiconductor Light Emitting Diodes (LEDs) have the advantages of high efficiency, long lifetime, environmental friendliness, and the like, and are widely used in various lighting applications. In the alternating current power supply occasion, the LED driving power supply needs to carry out input power factor correction, and because LED is as the load, its resistance is very little, and less ripple voltage will lead to great ripple current, takes place the stroboscopic, adopts the great electrolytic capacitor of appearance value to cushion usually, and the life of high quality electrolytic capacitor is far less than the life-span of LED chip. Therefore, in order to increase the service life of the LED driving power source, a capacitor for electrolysis needs to be removed.
Since the electrolytic capacitors are used to handle unbalanced power between the input and output, the solution considered from the energy storage network itself may mainly include from the viewpoint of reducing the difference between the input power and the output power or from the perspective of the energy storage network itself: the LED driving power supply is used for buffering double-frequency power based on a parallel structure and buffering double-frequency power based on a series structure, because the energy storage capacitor is not directly connected with the load in parallel, the capacitance value of the energy storage capacitor can be reduced in a mode of properly increasing direct current voltage or ripple voltage on the energy storage capacitor, so that the high-frequency capacitor with small capacitance value and long service life replaces an electrolytic capacitor, and the reliability of the LED driving power supply is improved.
At present, many researches are carried out to buffer double-frequency ripple power by analyzing an active power decoupling circuit, and based on the active power decoupling circuit with a parallel structure, when input power is greater than output power, redundant power is stored on an energy storage capacitor through the active power decoupling circuit, when the input power is less than the output power, the power stored in the energy storage capacitor compensates load through the active power decoupling circuit, and the minimum power processed by the active power decoupling circuit is double-frequency ripple power which is half; the active power decoupling circuit based on the series structure ensures that the alternating current component amplitudes of the ripple suppression capacitor and the energy storage capacitor are equal and the phases of the alternating current component amplitudes are opposite by controlling the active power decoupling circuit, so that the output current is constant, the power processed by the active power decoupling circuit is only very small ripple power, and the overall conversion efficiency of the LED driving power supply can be improved.
In an active power decoupling circuit topology based on a series structure, a capacitor is generally required to be introduced to the input side of the active power decoupling circuit to serve as an input source, and the active power decoupling circuit powered by an energy storage capacitor at the output side provides energy of the capacitor at the input side; or the input side of the active power decoupling circuit does not introduce a capacitor as an input source, and the alternating current input power supply directly provides energy to the active power decoupling circuit through the coupling inductor. Because the energy required for maintaining the voltage at two ends of the input side of the active power decoupling circuit is from an alternating current input power supply, the hidden danger that the instantaneous input power is lower than the expected output power in a short time, so that the voltage of the ripple elimination capacitor is out of control exists. At present, research has proposed that an auxiliary circuit is introduced to maintain the voltage of an input capacitor at a constant value, so as to ensure that the voltage of a ripple eliminating capacitor is not out of control, but the auxiliary circuit needs to additionally add a winding, a capacitor, a diode and the like, so that the circuit structure is complex, and the design cost and difficulty of driving are increased.
Disclosure of Invention
The invention aims to provide an LED driving power supply based on Flyback ripple suppression type electrolytic-capacitor-free, which can simultaneously meet the requirements of power factor correction and constant output current, has the advantages of no electrolytic capacitor, high power factor and high conversion efficiency, prolongs the service life of the LED driving power supply, improves the stability and the efficiency of the LED driving power supply, and solves the technical problem of potential hazard of capacitor voltage runaway caused by the fact that instantaneous input power is lower than expected output power in a short time in an active power decoupling circuit based on a series structure.
The invention adopts the following technical scheme for realizing the aim of the invention:
a Flyback ripple suppression type electrolytic capacitor-free LED driving power supply comprises: full-bridge rectification filter circuit, flyback PFC converter circuit, full-bridge circuit-based ripple suppression circuit, the control unit, wherein, flyback PFC converter circuit includes: the high-frequency transformer comprises a primary winding, a secondary main winding, a main power switch tube, a first power diode and an output energy storage capacitor; the ripple suppression unit includes: the high-frequency transformer comprises a secondary side auxiliary winding, a second power diode, a first power switch tube, a second power switch tube, a third power switch tube, a fourth power switch tube, an inductor and a ripple suppression capacitor; the control unit includes: a PFC controller and a ripple rejection controller. The single-phase alternating-current input power supply is connected with the middle point of a bridge arm of the full-bridge rectification filter circuit, a primary side circuit of the flyback PFC conversion circuit is connected to an output direct-current bus of the full-bridge rectification filter circuit, the flyback PFC conversion circuit is coupled with the ripple suppression unit, an output energy storage capacitor is connected with the ripple suppression capacitor in series, an LED load is connected to two ends of a series branch formed by the two capacitors in parallel, and a PFC controller in the control unit controls the output current of the LED driving power supply to realize circuit PFC; the ripple suppression controller controls ripple voltage at two ends of the ripple suppression capacitor, ripple suppression is achieved, and constant output current of the LED is achieved.
The positive output terminal of the direct current side of the full-bridge rectification filter circuit is connected with one end of a primary winding of a high-frequency transformer, the negative output terminal of the direct current side of the full-bridge rectification filter circuit is connected with the source electrode of a main power switch tube, the other end of the primary winding of the high-frequency transformer is connected with the drain electrode of the main power switch tube, one end of a secondary winding of the high-frequency transformer is connected with the anode of a first power diode, the cathode of the first power diode is connected with the positive electrode end of an output energy storage capacitor, the other end of the secondary winding of the high-frequency transformer is connected with the negative electrode of the output energy storage capacitor, the positive electrode of the output energy storage capacitor is connected with the anode of an LED load, one end of a secondary winding of the high-frequency transformer is connected with the anode of a second power diode, the cathode of a second power diode is connected with the drain electrode of the first power switch tube and the drain electrode of a third power switch tube, the other end of the secondary winding of the high-frequency transformer is connected with the source electrode of the second power switch tube and the source electrode of a fourth power switch tube, the source electrode of the first power switch tube and the drain electrode of the LED load are connected with the drain electrode of an inductor, the ripple wave suppression capacitor. One end of the primary winding of the high-frequency transformer, which is connected with the drain electrode of the main power switch tube, and one end of the secondary winding of the high-frequency transformer, which is connected with the anode of the first power diode, are homonymous ends, and one end of the primary winding of the high-frequency transformer, which is connected with the drain electrode of the main power switch tube, and one end of the secondary winding of the high-frequency transformer, which is connected with the anode of the second power diode, are homonymous ends.
Designing turn ratio N of secondary main winding and auxiliary winding of high-frequency transformer S1 :N S2 To the output voltage ratio V o1 : V o2 Mismatch, the following relationship is satisfied: n is a radical of S1 :N S2 <V o1 :V o2 When the ripple suppression unit does not work, the magnetic current flows to the secondary side main winding, and energy is transferred to the output energy storage capacitor to output a first output voltage; when the ripple suppression unit works, magnetic current flows to the auxiliary winding on the secondary side, and energy is transferred to the ripple suppression capacitor to output a second output voltage.
The control unit includes: the PFC controller works in a DCM mode and controls the main power switching tube to enable output current to follow reference current of the main power switching tube, so that circuit PFC is realized; the ripple suppression controller detects double-frequency ripple voltage in the first output voltage, the double-frequency ripple voltage is used as a reference value of the second output voltage after being inverted, all full-bridge power switching tubes in the ripple suppression unit are controlled through an accurately designed feedback loop to enable the second output voltage to follow the reference value of the second output voltage, ripple suppression is achieved, in each switching period, a carrier signal and a clock signal of the PFC controller are synchronized, and the ripple suppression controller is guaranteed to work under a correct time sequence.
The energy of the ripple suppression unit is not provided by the intermediate capacitor and is directly generated by the flyback PFC conversion circuit, so that the energy cycle number in the circuit is reduced; the energy that keeps ripple suppression electric capacity both ends voltage required comes from the AC input electricity in every switching cycle, exist in a certain period of time, instantaneous input power is less than required output power and leads to ripple suppression electric capacity both ends voltage out of control, introduce the full-bridge circuit among the ripple suppression unit, through the ripple suppression electric capacity voltage that produces the interchange, needn't add other auxiliary circuit and increase the direct current value that ripple suppression electric capacity voltage, directly offset ripple voltage, the energy transformation according to output energy storage capacitor in the unit cycle obtains output energy storage capacitor's appearance value expression:
ω＝2π/T line ，T line for the period of the input AC voltage, P o To output power, V o1_ave For outputting stored energyDC voltage of the capacitor, Δ V o1 For the ripple voltage of output energy storage capacitor, can be through producing suitable ripple voltage and direct current voltage to reduce energy storage capacitor capacitance value, realize going electrolytic capacitor, output energy storage capacitor and ripple suppression electric capacity are high frequency capacitor in the circuit.
The alternating current component amplitude of voltage equals and opposite phase on ripple suppression electric capacity and the output energy storage electric capacity, makes load current be direct current output, and the last permission of output energy storage electric capacity has great ripple voltage peak value and its ripple component homoenergetic to offset through the voltage ripple component on the ripple suppression electric capacity, and the expression of instantaneous output power is on the ripple suppression electric capacity:
v o2 (t) is the instantaneous voltage on the ripple rejection capacitor, and in order to ensure that the voltage on the ripple rejection capacitor is no longer out of control, it should be ensured that the instantaneous input power is greater than the instantaneous output power on the ripple rejection capacitor, that is:
by adopting the technical scheme, the invention has the following beneficial effects:
(1) The invention provides an LED driving power supply based on Flyback ripple suppression type electrolytic capacitor, which reduces the capacitance value of an energy storage capacitor by generating proper direct current voltage and ripple voltage on the energy storage capacitor, eliminates or reduces double frequency ripple of output current by replacing the electrolytic capacitor with a high-frequency capacitor, can realize power factor correction and constant output current at the same time, meets the requirements of LED driving characteristics, and prolongs the service life of LED driving.
(2) According to the Flyback ripple suppression type electrolytic capacitor-free LED driving power supply, the capacitor is not introduced into the energy input side of the ripple suppression unit to serve as an input source, energy is directly provided to the ripple suppression unit through the Flyback PFC conversion circuit and the coupling inductor, the energy cycle frequency in the circuit is reduced, the processing power of the active power decoupling circuit is further reduced, and the driving conversion efficiency is improved.
(3) The Flyback ripple suppression type electrolytic capacitor-free LED driving power supply provided by the invention solves the problem that the capacitor voltage is out of control in a short time due to the fact that the instantaneous input power is lower than the required output power, and improves the LED driving stability and efficiency.
Drawings
Fig. 1 is a circuit diagram of an LED driving power supply based on a Flyback ripple suppression type electrolytic capacitor-less according to the present invention.
Fig. 2 (a) and fig. 2 (b) are circuit diagrams of a PFC controller and a ripple suppression controller in an LED driving power control unit according to the present invention, respectively.
FIG. 3 (a) and FIG. 3 (b) are the ripple rejection capacitor voltage V in the power frequency cycle o2 Schematic diagram of the cause of the runaway and schematic diagram of the principle of solving the voltage runaway by reducing the instantaneous output power on the ripple suppression capacitor.
Fig. 4 is a waveform diagram of the switching period of the LED driving power supply of the present invention.
Fig. 5 is an equivalent circuit diagram of an operating mode 1 of an LED driving power supply according to an embodiment of the invention.
Fig. 6 is an equivalent circuit diagram of the LED driving power supply working mode 2 according to the embodiment of the invention.
Fig. 7 is an equivalent circuit diagram of the operating mode 3 of the LED driving power supply according to the embodiment of the invention.
Fig. 8 is an equivalent circuit diagram of the LED driving power source working mode 4 according to the embodiment of the invention.
FIG. 9 shows an embodiment of the present invention in which the LED driving power supply operates at the input voltage V in Input voltage V at 110VAC/50Hz in And an input current I in A waveform diagram of (a).
FIG. 10 shows an embodiment of the present invention in which the LED driving power supply operates at the input voltage V in Output voltage V at 110VAC/50Hz O And an input current I O A waveform diagram of (a).
FIG. 11 shows an embodiment of the present invention in which the LED driving power supply operates at the input voltage V in Output voltage V of output energy storage capacitor when =110VAC/50Hz o1 And ripple suppression capacitor output voltage V o2 A waveform diagram of (a).
FIG. 12 shows an embodiment of the present invention in which the LED driving power supply operates at the input voltage V in Waveform diagram of the ripple suppression effect of output voltage at =110VAC/50 Hz.
The reference numbers in the figures illustrate: 1 is a full-bridge rectification filter circuit, 2 is a flyback PFC conversion circuit, 3 is a ripple suppression unit, 4 is a control unit, 5 is an LED load, and Q is 1 Is a main power switch tube, S 1 、S 2 、S 3 、S 4 Is a first, a second, a third and a fourth power switch tube, N P Is a primary winding of a high-frequency transformer, N S1 Is a secondary primary winding of a high-frequency transformer, N S2 Is a secondary auxiliary winding of a high-frequency transformer, D r1 、D r2 、D r3 、D r4 Is a first, a second, a third and a fourth rectifying diode D 1 、D 2 Is a first and a second power diode, C o1 For outputting energy-storage capacitors, C o2 For ripple rejection capacitance, L f Is an inductor.
Detailed Description
The technical scheme of the invention is explained in detail in the following with reference to the attached drawings.
The invention discloses an LED driving power supply based on Flyback ripple suppression type electrolytic-capacitor-free LED driving power supply, as shown in figure 1, comprising: the device comprises a full-bridge rectification filter circuit 1, a flyback PFC conversion circuit 2, a ripple suppression unit 3 based on the full-bridge circuit, and a control unit 4 comprising a PFC controller and a ripple suppression controller. Single-phase ac input power supply V in The full-bridge rectifier filter circuit 1 is connected with the middle point of a bridge arm, an output direct current bus of the full-bridge rectifier filter circuit 1 is connected with a primary side circuit of a flyback PFC conversion circuit 2, the flyback PFC conversion circuit 2 is coupled with a ripple suppression unit 3, and a PFC controller in a control unit 4 controls output current to realize circuit PFC; the ripple suppression controller controls ripple voltage at two ends of the ripple suppression capacitor to achieve ripple suppression, the output energy storage capacitor is connected with the LED load, and constant output current of the LED is achieved.
Full bridge rectification filteringThe circuit 1 comprises: first rectifying diode D r1 And a second rectifying diode D r2 A bridge arm and a third rectifier diode D connected in series r3 And a fourth rectifying diode D r4 The other bridge arm is formed.
The flyback PFC converter circuit 2 includes: primary winding N of high-frequency transformer P And main power switch tube Q 1 Primary circuit formed by connecting in series and secondary main winding N of high-frequency transformer S1 A first power diode D 1 An output energy storage capacitor C o1 A secondary main circuit, a direct current side positive output end of a full-bridge rectification filter circuit 1 and a primary winding N of a high-frequency transformer which are connected in series P Is connected to the primary winding N of the high-frequency transformer P The other end of the main power switch tube Q 1 Is connected to the drain of the main power switch tube Q 1 The source of the high-frequency transformer is connected with the negative output end of the direct current side of the full-bridge rectification filter circuit 1, and the secondary side main winding N of the high-frequency transformer S1 And a first power diode D 1 Is connected to the anode of a first power diode D 1 Cathode and output energy storage capacitor C o1 Is connected with the positive polarity end of the output energy storage capacitor C o1 Negative terminal of and secondary main winding N of high-frequency transformer S1 Is connected with the other end of the output energy storage capacitor C o1 Is connected to the anode of the LED load.
The ripple suppression unit 3 includes: secondary auxiliary winding N of high-frequency transformer S2 A second power diode D 2 A first power switch tube S 1 A second power switch tube S 2 The third power switch tube S 3 The fourth power switch tube S 4 An inductor L f Ripple suppression capacitor C o2 Secondary auxiliary winding N of high-frequency transformer S2 And a second power diode D 2 Is connected to the anode of a second power diode D 2 Cathode of (1), first power switch tube S 1 Drain electrode of the third power switch tube S 3 Is connected with the drain electrode of the high-frequency transformer, and a secondary side auxiliary winding N of the high-frequency transformer S2 The other end of the first power switch tube S 2 Source electrode of, fourth power switch tube S 4 Is connected to the source of the first powerSwitch tube S 1 Source electrode of the first power switch tube S 2 Drain electrode of (1), inductor L f Is connected to one end of an inductor L f Another terminal of (1) and ripple rejection capacitor C o2 Is connected to the positive terminal of the third power switch tube S 3 Source electrode of, fourth power switch tube S 4 Drain electrode of (1), ripple suppression capacitor C o2 Is connected with the negative end and outputs an energy storage capacitor C o1 Negative terminal and ripple rejection capacitor C o2 Is connected to the positive terminal of the ripple rejection capacitor C o2 Is connected to the negative pole of the LED load. Primary winding N of high-frequency transformer P And main power switch tube Q 1 One end of the drain electrode is connected with the secondary side main winding N of the high-frequency transformer S1 And a first power diode D 1 The ends connected with the anode are the same name ends, and the primary winding N of the high-frequency transformer P And main power switch tube Q 1 One end of the drain electrode is connected with the auxiliary winding N of the secondary side of the high-frequency transformer S2 And a second power diode D 2 The ends of the anode connected are the same name ends.
The Flyback ripple suppression type electrolytic capacitor-free LED driving power supply shown in figure 1 is designed to have a turn ratio N of a high-frequency transformer S1 :N S2 Voltage to voltage ratio V o1 :V o2 Mismatch, the following relationship is satisfied: n is a radical of S1 :N S2 <V o1 : V o2 High frequency transformer in main power switch tube Q 1 The main power switch tube Q is electrified in the conduction time 1 After the power supply is turned off, the magnetic current needs to be kept flowing, and when the ripple suppression unit 3 does not work, the magnetic current flows to the secondary side main winding N S1 The winding inductance is denoted L mag_NS1 Energy is transferred to the output storage capacitor C o1 Output V o1 (ii) a When the ripple suppression unit 3 operates, a magnetic current flows to the secondary auxiliary winding N S2 The winding inductance is denoted L mag_NS2 Energy is transferred to ripple rejection capacitor C o2 Output V o2 。
The control unit includes: fig. 2 (a) is a schematic diagram of a PFC controller circuit, and fig. 2 (b) is a schematic diagram of a ripple rejection controller circuit. Flyback converterThe PFC controller works in a DCM mode and controls a main power switch tube Q 1 To make the output current I o Realizing a circuit PFC following the reference current; ripple rejection controller detects V o1 The ripple voltage is used as output V after being inverted o2 Reference voltage V of o2_ref Controlling a full-bridge power switch tube S through an accurately designed feedback loop 1 -S 4 ，V o2 And the reference voltage is followed to realize ripple suppression, and in each switching period, a carrier signal and a clock signal of the PFC controller are synchronized, so that the ripple suppression controller is ensured to work under a correct time sequence.
FIG. 3 (a) shows ripple rejection capacitor C in the power frequency cycle o2 Voltage V o2 The reason for runaway is schematically shown in FIG. 3 (b) for suppressing the capacitance C by reducing the ripple o2 Instantaneous output power P o2 (t) schematic diagram for solving voltage runaway principle. Maintaining voltage V across ripple rejection capacitor o2 The energy required comes from the ac input source V in each switching cycle in In the presence of [ t ] a ,t b ]Instantaneous input power P in time in (t) is less than V o2 (t) required instantaneous output Power P o2 (t), resulting in an output V o2 Runaway, as shown in FIG. 3 (a). The ripple suppression unit 3 of the present invention generates AC V through a full bridge circuit o2 No need of adding other auxiliary circuits to increase V o2 DC value of the capacitor C for suppressing ripple o2 Instantaneous output power P o2 (t) is decreased to ensure at [ t a ,t b ]The internal power curve is shown in FIG. 3 (b), and is higher than the instantaneous input power P only for a small time in (t), which can be approximately ignored, under which condition V o2 There is almost no runaway, thereby optimizing the ripple suppression effect.
Fig. 4 is a waveform diagram in a unit switching period, fig. 5 to 8 are working modes in the unit switching period, each switching period has 4 time intervals, namely 4 working modes, and the LED driving power supply periodically works in sequence from working mode 1 to working mode 4.
FIG. 5 is a diagram of a mode of operation 1[t 0 -t 1 ]When main power switchTube Q 1 On, the switching cycle is from time t 0 And starting. A primary winding of the high-frequency transformer obtains energy from alternating current input, and primary current rises from zero; when main power switch tube Q 1 At turn-off, the interval between the segments is at t 1 And (6) ending. During this time, the main power switch tube Q 1 The peak input switch current of (a) may be calculated as follows:
T on is a main power switch tube Q 1 On-time of L mag_NP Primary winding N of high-frequency transformer P An inductance value of, an average input current I of the switching period in_avg (t) sum peak switching Current I in_pk (t) the relational expression is:
T S is the switching period, and the effective value V of the input voltage is assumed to be zero power loss in_rms Input current effective value I in_rms And the output power P O The relational expression between them is:
main power switch tube Q under instantaneous voltage 1 Peak switching current I of Q1_pk The expression of (t) is:
first power diode D 1 Reverse voltage V across D1_R Can be expressed as: v D1_R ＝V in (t)+V o1 (t), a second power diode D 2 Reverse voltage V across D2_R Can be expressed as:
FIG. 6 shows a working mode 2[t 1 -t 2 ]Main power switch tube Q 1 Is turned off and the ripple suppression unit is still not operating. Connecting only the secondary primary winding N of the high-frequency transformer S1 First powerDiode D 1 And an output energy storage capacitor C o1 Provides a freewheeling loop for the transformer current. Therefore, during this time interval, the transformer inductance energy is transferred to the output energy storage capacitor, output V o1 . First power diode D 1 The peak switch current in the main power switch tube Q is equal to 1 Medium peak switching current, main power switching tube Q 1 Voltage V across ds_Q1 Expression (c): v ds_Q1 ＝V in (t)+V o1 (t) because of the secondary auxiliary winding N of the high-frequency transformer S2 The voltage of both ends is higher than the voltage V of the ripple suppression capacitor o2 (t), therefore the second power diode D 2 Forward bias, voltage V at two ends of full-bridge ripple suppression circuit ds_FB Can be expressed as:
FIG. 7 shows a working mode 3[t 2 -t 3 ]When the control signal v c And a carrier signal V tr2 When overlapping, at t 2 At the moment, the ripple suppression unit starts to work, and the high-frequency transformer current starts to flow from the secondary side main winding N S1 Commutation secondary auxiliary winding N S2 . Thus, the residual inductive energy of the high-frequency transformer is transferred to the ripple-suppression capacitor, and the output V o2 . Secondary auxiliary winding N S2 Is proportional to the square of the number of turns and can be expressed as:
main power switch tube Q 1 Voltage V ds_Q1 Expression (c):
first power diode D 1 Voltage V D1_R The expression of (c):
FIG. 8 is a mode of operation 4[t 3 -t 4 ]In order to achieve high power factor, the flyback PFC converter circuit is designed to operate in DCMAnd (6) rows. There is a very short time interval t before the start of the next switching cycle 3 -t 4 ]The high frequency transformer current remains zero until the next switching cycle. Since the magnetic current is already zero, the state of the ripple suppression unit is not important in this time interval. The ripple suppression unit may also be turned off during time intervals, if desired.
The above operation illustrates that the Flyback ripple suppression type electrolytic capacitor-free LED driving power supply of the present invention realizes single-stage power conversion. At time intervals t 0 -t 1 ]And energy is transmitted from an alternating current power supply to a primary winding of the high-frequency transformer. At time intervals t 1 -t 2 ]The high-frequency transformer will transfer most of its energy to output V o1 . At time intervals t 2 -t 3 ]During this period, the high-frequency transformer transfers its residual energy to the output V o2 . In one switching cycle, the high frequency transformer is charged and discharged only once, while transferring energy from the input to the output.
FIG. 9 shows an embodiment of the present invention in which the LED driving power supply operates at the input voltage V in =110VAC/50Hz, input voltage V in Input current I in And (4) waveform diagrams. Designing the main power switch Q 1 Operating frequency f s_Q1 100kHz, first to fourth power switch tubes S 1 -S 4 Operating frequency f s_FB 100kHz, high-frequency transformer N P :N S1 :N S2 80, output energy storage capacitor C o1 60uF, ripple rejection capacitor C o2 22uF, inductance L f At 28uH, output power P o It was 17.5W. Input voltage V in Input current I in The waveform diagram verifies that the proposed LED driving power supply realizes PFC.
FIG. 10 shows an embodiment of the present invention in which the LED driving power supply operates at the input voltage V in =110VAC/50Hz, output voltage V O Input current I O And (4) waveform diagrams. Designing parameters of the LED driving power supply as above, the average value V of the output voltage is verified o =50VDC, average value of output current I o =0.35A, essentially without electrolytic capacitanceRipple suppression is realized, and the design requirement of LED driving is met.
FIG. 11 shows an embodiment of the present invention in which the LED driving power supply operates at the input voltage V in =110VAC/50Hz, output energy storage capacitor C o1 Output voltage V o1 And ripple suppression capacitor C o2 Output voltage V o2 The waveform diagram shows the voltage value in the control circuit, namely the voltage value is sampled by 0.1 time, the ripple suppression of the LED driving power supply can be realized, and simultaneously V is shown o2 The voltage can not be out of control and well follows the given voltage V o2_ref 。
FIG. 12 shows an embodiment of the present invention in which the LED driving power supply operates at the input voltage V in =110VAC/50Hz, waveform diagram of ripple suppression effect of output voltage, and output voltage (V) without ripple suppression unit o1 -V o2 ) Comparing the waveforms, the actual output waveform V o The ripple voltage is obviously reduced, the LED driving power supply is verified to have good ripple rejection capability, and the stability of the LED driving power supply is improved.
Claims (1)
1. An LED drive power supply based on Flyback ripple suppression type electrolytic-capacitor-free LED drive power supply is characterized by comprising:
the middle point of the bridge arm of the full-bridge rectification filter circuit is connected with a single-phase alternating current input power supply,
the primary branch of the flyback PFC conversion circuit is connected between the positive and negative polarity direct current output buses of the full-bridge rectification filter circuit to form a primary loop, the secondary branch of the flyback PFC conversion circuit is connected with an output energy storage capacitor in series to form a secondary loop, and the primary loop is formed according to the expression:
determining the capacitance C of an output energy-storage capacitor o1 ，ω＝2π/T line ，T line Period of AC voltage output for single-phase AC input power supply, P o Is the output power of the LED drive circuit, V o1_ave For outputting DC voltage, Δ V, of the storage capacitor o1 For outputting the ripple voltage of the energy-storage capacitor according to the instantaneous input power P in (t) is greater than ripple rejection capacitance C o2 Up transientOutput power P o2 (t), i.e., according to the relationship:
determining a suitable output energy storage capacitor C o1 Ripple voltage Δ V of o1 Value of (a), p in (t) min Is the minimum value of instantaneous input power, p o2 (t) max Capacitor C for suppressing ripple o2 Maximum value of upper instantaneous output power, V o For the output voltage of the LED driving circuit,
a ripple suppression unit for converting part of energy coupled from the primary loop of the flyback PFC converter into ripple voltage and applying the ripple voltage to a ripple suppression capacitor connected to the output port, wherein the ripple suppression capacitor is connected in series with the output energy storage capacitor to form the output port of the LED drive circuit, the AC component of the voltage of the ripple suppression capacitor is equal in amplitude and opposite in phase to the AC component of the voltage of the output energy storage capacitor, and,
the control unit is used for carrying out closed-loop control on the output current of the LED driving circuit, generating a primary side loop switch control signal of the flyback PFC conversion circuit working in a DCM mode, extracting frequency-doubled ripple voltage from the voltage of the output energy-storage capacitor, inverting the frequency-doubled ripple voltage, generating a ripple suppression capacitor voltage reference value, and generating a ripple suppression unit switch control signal of which the ripple suppression capacitor voltage follows the reference value; wherein, the first and the second end of the pipe are connected with each other,
the primary side loop of the flyback PFC conversion circuit comprises: the high-frequency transformer primary winding comprises a high-frequency transformer primary winding and a main power switch tube, wherein one end of the high-frequency transformer primary winding is connected with a positive polarity direct current output bus of a full-bridge rectification filter circuit; the secondary side loop of the flyback PFC conversion circuit comprises: the high-frequency transformer comprises a high-frequency transformer secondary winding, a first power diode and an output energy storage capacitor, wherein one end of the high-frequency transformer secondary winding is connected with the anode of the first power diode, the cathode of the first power diode is connected with the positive end of the output energy storage capacitor, the negative end of the output energy storage capacitor is connected with the other end of the high-frequency transformer secondary winding, and one end of the high-frequency transformer primary winding, which is connected with the drain electrode of a main power switch tube, and one end of the high-frequency transformer secondary winding, which is connected with the anode of the first power diode, are homonymous ends;
the ripple suppression unit includes: the secondary side auxiliary winding of the high-frequency transformer, a second power diode, a full-bridge inverter circuit, an inductor and a ripple suppression capacitor, wherein one end of the secondary side auxiliary winding of the high-frequency transformer is connected with the anode of the second power diode, the cathode of the second power diode is connected with a common contact of a bridge arm of the full-bridge inverter circuit, the other end of the secondary side auxiliary winding of the high-frequency transformer is connected with a common contact of another bridge arm of the full-bridge inverter circuit, a branch formed by serially connecting the inductor and the ripple suppression capacitor is connected to the middle point of the bridge arm of the full-bridge inverter circuit, one end of the primary side winding of the high-frequency transformer, which is connected with the drain electrode of a main power switch tube, and one end of the secondary side auxiliary winding of the high-frequency transformer, which is connected with the anode of the second power diode, are the same-name ends, and the turn ratio of the secondary side winding of the high-frequency transformer and the auxiliary winding is N S1 :N S2 And the voltage ratio V of the secondary side output of the flyback PFC conversion circuit to the output of the ripple suppression unit o1 :V o2 Mismatch, the following relationship is satisfied: n is a radical of S1 :N S2 <V o1 :V o2 。
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| CN112867204B (en) * | 2021-02-08 | 2023-04-18 | 杭州优特电源有限公司 | Auxiliary power supply |
| CN117397156A (en) | 2021-05-28 | 2024-01-12 | 昕诺飞控股有限公司 | Driver for driving a load such as an LED load |
| CN114205954A (en) * | 2021-12-30 | 2022-03-18 | 福州大学 | Electrolytic-capacitor-free control method for improved Sepic-LED driving circuit |
| CN114679816B (en) * | 2021-12-31 | 2023-05-23 | 福州大学 | Intermediate capacitance current control method for single-stage LED driving circuit without electrolytic capacitor |
| CN117595644A (en) * | 2024-01-18 | 2024-02-23 | 武汉理工大学 | Electrolytic capacitor-free V2G converter based on ripple reverse compensation |
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