Dual-path flyback DCDC auxiliary power supply with low cross regulation rate and lossless absorption

Abstract

Disclosed in the present invention is a dual-path flyback DCDC auxiliary power supply with a low cross regulation rate and lossless absorption. The auxiliary power supply comprises a DC power supply, a first capacitor, a primary-side leakage inductance lossless absorption circuit, a transformer, and a secondary-side synchronous rectification current balancing circuit connected in sequence; the transformer comprises a primary-side primary winding NP1, a primary-side secondary winding NP2, a secondary-side primary feedback winding NS1, and a secondary-side secondary feedback winding NS2; the primary-side leakage inductance lossless absorption circuit comprises a first switching transistor, a diode, a second capacitor, a leakage inductor, an excitation inductor, and a primary-side secondary winding NP2; the secondary-side synchronous rectification current balancing circuit comprises a second synchronous rectifier, a third synchronous rectifier, a third capacitor, a fourth capacitor, a first load, and a second load. By means of the circuit design, the use of the primary-side leakage inductance lossless absorption circuit reduces the circuit loss and improves the power supply efficiency; and average energy distribution is realized by means of the control of the two synchronous rectifiers, thereby reducing the power supply cross regulation rate.

Description

A dual-path flyback DCDC auxiliary power supply with low cross-regulation and lossless absorption Technical Field

[0001] The present invention relates to the technical field of multi-channel auxiliary power supplies, and in particular to a dual-channel flyback DCDC auxiliary power supply with low cross-regulation rate and lossless absorption. Background Art

[0002] With the increasing popularity and diversification of electronic devices, the requirements for power supplies are becoming increasingly higher, especially in some key application areas such as photovoltaic energy storage, industry and medical fields, where the requirements for power supply reliability and stability are particularly stringent.

[0003] Among them, the flyback topology power supply includes an RCD absorption circuit on the primary side of the transformer and an output inductor and a freewheeling diode on the secondary side of the transformer, and the primary and secondary sides are electrically isolated. The flyback topology power supply is widely used in some occasions where the power output power requirement is less than 200w due to its advantages such as low cost, wide input range, simple topology and stable output.

[0004] However, existing flyback topology power supplies have the following problems: First, the RCD absorption circuit on the primary side of the transformer absorbs power while suppressing leakage inductance spikes, which causes circuit loss and reduces power supply efficiency; second, when there are multiple outputs, a slave output winding needs to be added on the secondary side of the transformer. However, since the circuit only uses closed-loop feedback voltage regulation for the main output circuit, the slave output circuit will be affected by the fluctuations of the main output circuit load, its own load, and the loads of other slave output circuits, resulting in a sudden increase or decrease in the output voltage, resulting in a high cross-regulation rate of the power supply.

[0005] Summary of the Invention

[0006] In order to avoid circuit loss, improve power supply efficiency, and reduce power supply cross-regulation rate, the present application provides a dual-path flyback DCDC auxiliary power supply with low cross-regulation rate and lossless absorption.

[0007] This application provides a dual-path flyback DC / DC auxiliary power supply with low cross-regulation rate and lossless absorption, which adopts the following technical solution:

[0008] The auxiliary power supply includes a DC power supply Uin, a first capacitor C1, a primary leakage inductance lossless absorption circuit, a transformer T1 and a secondary synchronous rectification current balancing circuit connected in sequence; the transformer T1 includes a primary main winding N P1 、Primary secondary winding N P2 , secondary side main feedback winding N S1 , secondary side secondary feedback winding N S2 ;

[0009] The primary leakage inductance lossless absorption circuit includes a first switch tube Q1, a diode D1, a second capacitor C2, a leakage inductance Lr, an excitation inductance Lm, a primary secondary winding N P2 The secondary side synchronous rectification current balancing circuit includes a second synchronous rectifier Q2, a third synchronous rectifier Q3, a third capacitor Co1, a fourth capacitor Co2, a first load R1 and a second load R2;

[0010] The positive electrode of the first capacitor C1 is connected to the positive electrode of the DC power supply Uin, the cathode of the diode D1, and one end of the leakage inductor Lr respectively, and the negative electrode of the first capacitor C1 is connected to the negative electrode of the DC power supply Uin, the source of the first switch tube Q1, and the primary secondary winding N P2 The same-name end of the primary and secondary windings N P2 The opposite ends are connected to the anode of the diode D1 and the negative electrode of the second capacitor C2 respectively; the primary main winding N P1 The same-name ends are connected to the other end of the leakage inductance Lr and one end of the excitation inductance Lm respectively; the primary main winding N P1 The opposite ends of the terminals are connected to the other end of the magnetizing inductor Lm, the positive electrode of the second capacitor C2, and the drain of the first switch tube Q1 respectively;

[0011] The secondary side main feedback winding N S1 The same-name terminals are connected to the negative electrode of the third capacitor Co1, the negative electrode of the first load R1, the negative electrode of the fourth capacitor Co2, and the negative electrode of the second load R2, respectively. The secondary main feedback winding N S1 The opposite end is connected to the source of the second synchronous rectifier Q2, and the secondary feedback winding N S2 The same-name end is connected to the drain of the second synchronous rectifier Q2, the positive electrode of the third capacitor Co1, and the positive electrode of the first load R1 respectively, and the secondary feedback winding N S2 The opposite end is connected to the source of the third synchronous rectifier Q3, and the drain of the third synchronous rectifier Q3 is connected to the positive electrode of the fourth capacitor Co2 and the positive electrode of the second load R2 respectively; the main output of the auxiliary power supply is connected to the first load R1, and the slave output of the auxiliary power supply is connected to the second load R2.

[0012] By adopting the above technical solution, on the one hand, a primary leakage inductance lossless absorption circuit is adopted. By directly winding the winding on the primary side of the transformer and adding a clamping diode, the leakage inductance spike can be effectively suppressed, avoiding the power loss problem caused by the traditional RCD absorption circuit, reducing circuit loss and improving the efficiency of the power supply. By directly winding the winding, the switch tube and the high-side switch tube driving circuit in the traditional RCD absorption circuit are eliminated, reducing the cost and design difficulty, and reducing the size of the power supply board; on the other hand, through the control of the two synchronous rectifier tubes on the secondary side of the transformer, the energy can be evenly distributed, so that regardless of whether the main output is heavy loaded or light loaded, the output voltage of the slave can change adaptively, avoiding the phenomenon of sudden increase or decrease in output voltage, and reducing the cross regulation rate of the power supply.

[0013] In a specific implementation scheme, the auxiliary power supply operates in DCM mode, the main output of the auxiliary power supply is heavily loaded, and the slave output of the auxiliary power supply is lightly loaded, or the main output of the auxiliary power supply is lightly loaded, and the slave output of the auxiliary power supply is heavily loaded;

[0014] When the main output of the auxiliary power supply is heavily loaded and the slave output of the auxiliary power supply is lightly loaded, the auxiliary power supply sequentially includes four working modes within a complete signal cycle: a first working mode, a second working mode, a third working mode, and a fourth working mode;

[0015] When the main output of the auxiliary power supply is lightly loaded and the slave output of the auxiliary power supply is heavily loaded, the auxiliary power supply includes four working modes in sequence within a complete signal cycle: a fifth working mode, a sixth working mode, a seventh working mode, and an eighth working mode.

[0016] In a specific implementation scheme, in the first working mode [t0-t1], at time t0, the first switch tube Q1 is turned on, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned off; the DC power supply Uin is filtered by the first capacitor C1 and then charges the excitation inductor Lm and the leakage inductor Lr through the first switch tube Q1; the second capacitor C2 absorbs the leakage inductance energy and passes it to the primary secondary winding N through the first switch tube Q1. P2 charging; the third capacitor Co1 supplies power to the first load R1; the fourth capacitor Co2 supplies power to the second load R2.

[0017] By adopting the above technical solution, in this stage, the first load R1 is powered by the third capacitor Co1, and the second load R2 is powered by the fourth capacitor Co2.

[0018] In a specific implementation scheme, in the second working mode [t1-t2], at time t1, the first switch tube Q1 is turned off, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned on; the primary secondary winding N P2The energy is fed back to the first capacitor C1 through the diode D1; the leakage inductor Lr charges the second capacitor C2 through the diode D1; the excitation inductor Lm transfers the energy to the secondary side main feedback winding N S1 and the secondary feedback winding N S2 ; Secondary side main feedback winding N S1 The third capacitor Co1 is charged and the first load R1 is powered by the second synchronous rectifier Q2; the secondary feedback winding N S2 Through the second synchronous rectifier Q2, the third synchronous rectifier Q3, the secondary side main feedback winding N S1 The fourth capacitor Co2 is charged and the second load R2 is powered.

[0019] By adopting the above technical solution, in this stage, the secondary side main feedback winding N S1 Power is supplied to the first load R1 , and power is supplied to the second load R2 via the fourth capacitor Co2 .

[0020] In a specific implementation scheme, in the third working mode [t2-t3], at time t2, the first switch tube Q1 remains off, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 remain on; the secondary side auxiliary feedback winding N S2 The output current drops to 0 at time t2 and starts to flow in the reverse direction. The secondary feedback winding N S2 The remaining energy and the secondary main feedback winding N S1 Together, the third capacitor Co1 is charged through the second synchronous rectifier Q2 and supplies power to the first load R1; the fourth capacitor Co2 supplies power to the second load R2.

[0021] By adopting the above technical solution, in this stage, the secondary feedback winding N S2 and the secondary side main feedback winding N S1 The first load R1 is powered together, and the second load R2 is powered through the fourth capacitor Co2.

[0022] In a specific implementation scheme, in the fourth working mode [t3-t4], at time t3, the first switch tube Q1 remains off, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned off; the secondary side main feedback winding N S1 The output current drops to 0 at time t3; the third capacitor Co1 supplies power to the first load R1; and the fourth capacitor Co2 supplies power to the second load R2.

[0023] By adopting the above technical solution, in this stage, the first load R1 is powered by the third capacitor Co1, and the second load R2 is powered by the fourth capacitor Co2.

[0024] In a specific implementation scheme, in the fifth working mode [t6-t7], at time t6, the first switch tube Q1 is turned on, and the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned off; the DC power supply Uin is filtered by the first capacitor C1 and then charges the excitation inductor Lm and the leakage inductor Lr through the first switch tube Q1; the second capacitor C2 absorbs the leakage inductance energy and transmits it to the primary secondary winding N through the first switch tube Q1. P2 charging; the third capacitor Co1 supplies power to the first load R1; the fourth capacitor Co2 supplies power to the second load R2.

[0025] By adopting the above technical solution, in this stage, the first load R1 is powered by the third capacitor Co1, and the second load R2 is powered by the fourth capacitor Co2.

[0026] In a specific implementation scheme, in the sixth working mode [t7-t8], at time t7, the first switch tube Q1 is turned off, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned on; the primary secondary winding N P2 The energy is fed back to the first capacitor C1 through the diode D1; the leakage inductor Lr charges the second capacitor C2 through the diode D1; the excitation inductor Lm transfers the energy to the secondary side main feedback winding N S1 and the secondary feedback winding N S2 ; Secondary side main feedback winding N S1 The third capacitor Co1 is charged and the first load R1 is powered by the second synchronous rectifier Q2; the secondary feedback winding N S2 Through the second synchronous rectifier Q2, the third synchronous rectifier Q3, the secondary side main feedback winding N S1 The fourth capacitor Co2 is charged and the second load R2 is powered.

[0027] By adopting the above technical solution, in this stage, the secondary side main feedback winding N S1 Power the first load R1 through the secondary feedback winding N S2 The second load R2 is powered.

[0028] In a specific implementation scheme, in the seventh working mode [t8-t9], at time t8, the first switch tube Q1 remains off, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 remain on; the secondary side main feedback winding N S1 The output current drops to 0 at time t8 and starts to flow in the reverse direction. The secondary side main feedback winding N S1 The remaining energy and the secondary feedback winding N S2 Together, the fourth capacitor Co2 is charged through the third synchronous rectifier Q3 and the second load R2 is supplied with power; the third capacitor Co1 supplies power to the first load R1.

[0029] By adopting the above technical solution, in this stage, the secondary side main feedback winding N S1 and the secondary feedback winding N S2 The second load R2 is powered together, and the first load R1 is powered through the third capacitor Co1.

[0030] In a specific embodiment, in the eighth working mode [t9-t 10 ], at time t9, the first switch tube Q1 remains off, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned off; the secondary side main feedback winding N S1 The output current drops to 0 at time t9; the third capacitor Co1 supplies power to the first load R1; and the fourth capacitor Co2 supplies power to the second load R2.

[0031] By adopting the above technical solution, in this stage, the first load R1 is powered by the third capacitor Co1, and the second load R2 is powered by the fourth capacitor Co2.

[0032] In summary, the technical solution of this application includes at least the following beneficial technical effects:

[0033] 1. The primary-side leakage inductance lossless absorption circuit is adopted. By directly winding the winding on the primary side of the transformer and adding a clamping diode, the leakage inductance spike can be effectively suppressed, avoiding the power loss problem caused by the traditional RCD absorption circuit, reducing circuit loss while improving the efficiency of the power supply. In addition, by directly winding the winding, the switch tube and high-side switch tube driving circuit in the traditional RCD absorption circuit are eliminated, reducing the cost and design difficulty, and reducing the size of the power supply board;

[0034] 2. Through the control of the two synchronous rectifiers on the secondary side of the transformer, energy is evenly distributed, so that the output voltage of the slave circuit can change adaptively regardless of whether the main circuit output is heavily loaded or lightly loaded, avoiding the phenomenon of sudden increase or decrease in output voltage, improving the stability of the output voltage, and reducing the cross-regulation rate of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG1 is a topology diagram of a dual-path flyback DCDC auxiliary power supply with low cross-regulation rate and lossless absorption in an embodiment of the present application;

[0036] FIG2 is a diagram showing the current waveforms of related components in a complete signal cycle when the auxiliary power supply output is heavily loaded on the main output and lightly loaded on the slave output in an embodiment of the present application;

[0037] FIG3 is a diagram showing the auxiliary power supply operation mode during the t0-t1 stage and the t6-t7 stage in an embodiment of the present application;

[0038] FIG4 is a diagram showing the auxiliary power supply operation mode during the t1-t2 stage and the t7-t8 stage in an embodiment of the present application;

[0039] FIG5 is a diagram showing the auxiliary power supply operation mode during the t2-t3 phase according to an embodiment of the present application;

[0040] FIG6 is a diagram of the t3-t4 stage, t9-t 10 Stage auxiliary power supply working mode diagram;

[0041] FIG7 shows the current waveforms of the relevant components in a complete signal cycle when the auxiliary power supply output is lightly loaded on the main output and heavily loaded on the slave output in an embodiment of the present application;

[0042] FIG8 is a working mode diagram of the auxiliary power supply during the t8-t9 phase in an embodiment of the present application. DETAILED DESCRIPTION

[0043] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0044] The present application discloses a dual-path flyback DCDC auxiliary power supply with low cross-regulation rate and lossless absorption. Referring to FIG1 , the auxiliary power supply includes a DC power supply Uin, a first capacitor C1, a primary leakage inductance lossless absorption circuit, a transformer T1, and a secondary synchronous rectification current balancing circuit connected in sequence; wherein the transformer T1 includes a primary main winding N P1 、Primary secondary winding N P2 , secondary side main feedback winding N S1 , secondary side secondary feedback winding N S2 The following is a detailed description of the components in the primary-side leakage inductance lossless absorption circuit and the secondary-side synchronous rectification current balancing circuit:

[0045] 1, the primary leakage inductance lossless absorption circuit includes a first switch tube Q1, a diode D1, a second capacitor C2, a leakage inductance Lr, an excitation inductance Lm, a primary secondary winding N P2 The secondary side synchronous rectification current balancing circuit includes a second synchronous rectifier Q2, a third synchronous rectifier Q3, a third capacitor Co1, a fourth capacitor Co2, a first load R1 and a second load R2.

[0046] The connection relationship between the components of the auxiliary power system of this embodiment is described in detail below:

[0047] 1, the positive electrode of the first capacitor C1 is connected to the positive electrode of the DC power supply Uin, the cathode of the diode D1, and one end of the leakage inductor Lr, and the negative electrode of the first capacitor C1 is connected to the negative electrode of the DC power supply Uin, the source of the first switch Q1, and the primary secondary winding N P2 The same-name end of the primary and secondary windings N P2The opposite ends are connected to the anode of the diode D1 and the negative electrode of the second capacitor C2 respectively; the primary main winding N P1 The same-name ends are connected to the other end of the leakage inductance Lr and one end of the excitation inductance Lm respectively; the primary main winding N P1 The opposite ends of the terminals are connected to the other end of the magnetizing inductor Lm, the positive electrode of the second capacitor C2, and the drain of the first switch tube Q1 respectively;

[0048] Secondary side main feedback winding N S1 The same-name terminals are connected to the negative electrode of the third capacitor Co1, the negative electrode of the first load R1, the negative electrode of the fourth capacitor Co2, and the negative electrode of the second load R2, respectively. The secondary main feedback winding N S1 The opposite end is connected to the source of the second synchronous rectifier Q2, and the secondary feedback winding N S2 The same-name end is connected to the drain of the second synchronous rectifier Q2, the positive electrode of the third capacitor Co1, and the positive electrode of the first load R1 respectively, and the secondary feedback winding N S2 The opposite end of the transistor is connected to the source of the third synchronous rectifier Q3, and the drain of the third synchronous rectifier Q3 is connected to the positive electrode of the fourth capacitor Co2 and the positive electrode of the second load R2 respectively.

[0049] In particular, in this embodiment, the main output of the dual-path flyback DCDC auxiliary power supply with low cross-regulation and lossless absorption is connected to the first load R1, and the slave output of the auxiliary power supply is connected to the second load R2. Referring to Figure 1, the main output voltage Uo1 of the auxiliary power supply is received at both ends of the first load R1, and the slave output voltage Uo2 of the auxiliary power supply is received at both ends of the second load R2.

[0050] Furthermore, in this embodiment, the first capacitor C1 is an energy storage filter capacitor, which has the functions of filtering and energy storage; the diode D1 is a clamping diode, which has the function of protecting the circuit; the second capacitor C2 is an absorption capacitor, which has the function of absorbing peak voltage; the third capacitor Co1 and the fourth capacitor Co2 are both output filter capacitors, which have the function of filtering the output voltage; the leakage inductance Lr is the leakage inductance of the transformer T1, that is, the magnetic lines of force generated by the coil of the transformer T1 cannot all pass through the secondary coil and generate leakage magnetic inductance; the excitation inductance Lm is the excitation inductance of the transformer T1, that is, the basis for the energy of the transformer T1 to be transmitted from the primary side to the secondary side. The excitation inductance Lm generates magnetic flux that is transmitted to the secondary side through the magnetic core, thereby generating an induced voltage on the secondary side.

[0051] The following, with reference to Figures 2 to 8 , specifically describes the charging and discharging conditions of various components when the dual-path flyback DCDC auxiliary power supply with low cross-regulation and lossless absorption operates in DCM mode (discontinuous conduction mode) with the auxiliary power supply's main output heavily loaded and the auxiliary power supply's secondary output lightly loaded. Furthermore, the charging and discharging conditions of various components when the auxiliary power supply operates in DCM mode with the auxiliary power supply's main output lightly loaded and the auxiliary power supply's secondary output heavily loaded. The terms "heavy load" and "light load" refer to the load power carried by the auxiliary power supply output. A greater load power corresponds to a heavier load, which is referred to as "heavy load." A smaller load power corresponds to a lighter load, which is referred to as "light load." No load is referred to as "no load."

[0052] When the auxiliary power supply operates in DCM mode, and the main output of the auxiliary power supply is heavily loaded and the slave output is lightly loaded, the auxiliary power supply includes four operating modes in sequence within a complete signal cycle: a first operating mode, a second operating mode, a third operating mode, and a fourth operating mode.

[0053] In the first working mode [t0-t1], at time t0, the first switch tube Q1 is turned on, and the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned off; then, referring to FIG3 , on the primary side of the transformer T1, the DC power supply Uin is filtered by the first capacitor C1 and then charges the excitation inductor Lm and the leakage inductor Lr through the first switch tube Q1, and the second capacitor C2 transfers the leakage inductance energy absorbed in the previous stage to the primary secondary winding N through the first switch tube Q1. P2 Charging; on the secondary side of the transformer, the third capacitor Co1 supplies power to the first load R1, and the fourth capacitor Co2 supplies power to the second load R2.

[0054] At this stage, the current direction of the leakage inductance Lr and the primary secondary winding N P2 The current direction is shown in FIG3 , and referring to FIG2 , the current i of the leakage inductance Lr Lmr It gradually increases from 0 and reaches its peak at time t1; the primary and secondary windings N P2 The current i NP2 It also gradually increases from 0 and reaches its peak at time t1.

[0055] In the second working mode [t1-t2], at time t1, the first switch tube Q1 is turned off, and the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned on; then referring to FIG4, on the primary side of the transformer T1, when the first switch tube Q1 is turned off, due to the primary secondary winding N P2 The current cannot change transiently, so that the anode potential of diode D1 is higher than the cathode potential, then diode D1 is turned on, and the primary secondary winding N P2The energy is fed back to the first capacitor C1 through the diode D1. In addition, since the leakage inductance Lr energy cannot be transferred to the secondary side of the transformer T1, the leakage inductance Lr charges the second capacitor C2 through the diode D1. The excitation inductance Lm transfers the energy to the secondary side main feedback winding N S1 and the secondary feedback winding N S2 ; On the secondary side of transformer T1, the secondary main feedback winding N S1 The third capacitor Co1 is charged and the first load R1 is powered by the second synchronous rectifier Q2; the secondary feedback winding N S2 Through the second synchronous rectifier Q2, the third synchronous rectifier Q3, the secondary side main feedback winding N S1 The fourth capacitor Co2 is charged and the second load R2 is powered.

[0056] At this stage, the current direction of the leakage inductance Lr, the primary secondary winding N P2 The current direction of the secondary feedback winding N S2 The current direction and the secondary side main feedback winding N S1 The current direction is shown in FIG4, and referring to FIG2, the current i of the leakage inductance Lr Lmr Gradually decreases and drops to 0 at time t2; the primary and secondary windings N P2 The current i NP2 Also gradually decreases and drops to 0 at time t2; the secondary side main feedback winding N S1 The current i o1 It reaches its maximum value at time t1 and gradually decreases during this stage, but does not drop to 0 at time t2; the secondary side secondary feedback winding N S2 The current i o2 It reaches its maximum at time t1, gradually decreases during this stage, and drops to 0 at time t2.

[0057] In the third working mode [t2-t3], at time t2, the first switch tube Q1 remains off, and the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 remain on; then referring to FIG5 , on the secondary side of the transformer T1, the secondary feedback winding N S2 The current i o2 At t2, it drops to 0 and begins to flow in the reverse direction. The secondary feedback winding N S2 The remaining energy flows into the secondary main feedback winding N S1 The circuit and the secondary side main feedback winding N S1 Together, the third capacitor Co1 is charged through the second synchronous rectifier Q2 and the first load R1 is powered. The first load R1 continues to consume the secondary feedback winding N S2 The current i o2 At the same time, the fourth capacitor Co2 supplies power to the second load R2.

[0058] In this stage, the secondary feedback winding N S2 The current direction and the secondary side main feedback winding N S1 The current direction is shown in FIG5 , and referring to FIG2 , the secondary feedback winding N S2 The current i o2 The direction starts to reverse from time t2; the secondary side main feedback winding N S1 The current i o1 Although it is still decreasing gradually, due to the secondary feedback winding N S2 The remaining energy flows into the secondary main feedback winding N S1 The circuit charges the third capacitor Co1 and supplies power to the first load R1, so the current i o1 The slope of the decline is smaller than that of the t1-t2 stage, and at t3 the current i o1 Dropped to 0.

[0059] In the fourth working mode [t3-t4], at time t3, the first switch tube Q1 remains off, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned off; the secondary side main feedback winding N S1 The output current drops to 0 at time t3; referring to FIG6 , on the secondary side of the transformer T1 , the auxiliary power supply still has the third capacitor Co1 to supply power to the first load R1 ; the fourth capacitor Co2 to supply power to the second load R2 .

[0060] Therefore, it can be obtained that at time t4, a complete signal cycle ends. During the t0-t1 period, the first load R1 is powered by the third capacitor Co1, and the second load R2 is powered by the fourth capacitor Co2. During the t1-t2 period, the secondary side main feedback winding N S1 Power is supplied to the first load R1 and the second load R2 via the fourth capacitor Co2; during the t2-t3 phase, the secondary feedback winding N S2 and the secondary side main feedback winding N S1 Power is supplied to the first load R1 through the third capacitor Co1 and to the second load R2 through the fourth capacitor Co2. During the t3-t4 period, power is supplied to the first load R1 through the third capacitor Co1 and to the second load R2 through the fourth capacitor Co2. During this period, the two currents on the secondary side of transformer T1 are evenly distributed, making the output voltages of both the master and slave paths relatively stable.

[0061] Furthermore, it can be seen that in the first working mode [t0-t1] stage, the second capacitor C2 transfers the leakage inductance energy absorbed in the previous stage to the primary secondary winding N through the first switch tube Q1. P2Charging, where the leakage inductance energy absorbed by the second capacitor C2 in the previous stage is obtained by the leakage inductance Lr charging the second capacitor C2 through the diode D1 during the second working mode [t1-t2] stage in the previous signal cycle.

[0062] 2 , starting from the next signal cycle at time t5 , the working state of the auxiliary power supply in the next signal cycle is still as described in the first to fourth working modes.

[0063] When the auxiliary power supply operates in DCM mode, and the main output of the auxiliary power supply is lightly loaded and the slave output is heavily loaded, the auxiliary power supply includes four working modes in sequence within a complete signal cycle: the fifth working mode, the sixth working mode, the seventh working mode, and the eighth working mode.

[0064] In the fifth working mode [t6-t7], at time t6, the first switch tube Q1 is turned on, and the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned off; then the charging and discharging conditions of the components in the auxiliary power supply at this stage are the same as those in the first working mode [t0-t1] stage, referring to Figure 3, that is, the DC power supply Uin charges the excitation inductor Lm and the leakage inductor Lr, and the second capacitor C2 charges the primary secondary winding N P2 Charging, the third capacitor Co1 supplies power to the first load R1, and the fourth capacitor Co2 supplies power to the second load R2. For details, please refer to the description of the first working mode, which will not be repeated here.

[0065] At this stage, the current direction of the leakage inductance Lr and the primary secondary winding N P2 The current direction is also shown in FIG3 , and referring to FIG7 , the current i of the leakage inductance Lr Lmr It gradually increases from 0 and reaches its peak at t7; the primary and secondary windings N P2 The current i NP2 It also gradually increases from 0 and reaches its peak at time t7.

[0066] In the sixth working mode [t7-t8], at time t7, the first switch tube Q1 is turned off, and the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned on; also referring to FIG4 , the charging and discharging conditions of the components in the auxiliary power supply at this stage are the same as those in the second working mode [t1-t2] stage, that is, the primary secondary winding N P2 The energy is fed back to the first capacitor C1 through the diode D1, the leakage inductor Lr charges the second capacitor C2 through the diode D1, and the excitation inductor Lm transfers the energy to the secondary side main feedback winding N S1 and the secondary feedback winding N S2 , secondary side main feedback winding N S1 Charge the third capacitor Co1 and supply power to the first load R1; the secondary feedback winding N S2For charging the fourth capacitor Co2 and supplying power to the second load R2 , please refer to the description of the second working mode for details, which will not be repeated here.

[0067] At this stage, the current direction of the leakage inductance Lr, the primary secondary winding N P2 The current direction of the secondary feedback winding N S2 The current direction and the secondary side main feedback winding N S1 The current direction is shown in FIG4 , and referring to FIG7 , the current i of the leakage inductance Lr Lmr It also decreases gradually and drops to 0 at time t8; the primary and secondary windings N P2 The current i NP2 It also decreases gradually and drops to 0 at time t8; the secondary side main feedback winding N S1 The current i o1 It reaches its maximum value at t7 and gradually decreases during this stage. The secondary feedback winding N S2 The current i o2 It reaches the maximum at t7 and gradually decreases during this stage. However, the specific change value of the current in this stage is different from that in the second working mode [t1-t2] stage. Referring to Figure 7, the secondary side main feedback winding N S1 The current i o1 At t8, it drops to 0, and the secondary feedback winding N S2 The current i o2 At t8, it did not drop to 0.

[0068] In the seventh working mode [t8-t9], at time t8, the first switch tube Q1 remains off, and the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 remain on; then referring to FIG8 , on the secondary side of the transformer T1, the secondary main feedback winding N S1 The output current i o1 At t8, it drops to 0 and starts to flow in the reverse direction. The secondary side main feedback winding N S1 The remaining energy flows into the secondary feedback winding N S2 The circuit and the secondary feedback winding N S2 Together, the fourth capacitor Co2 is charged through the third synchronous rectifier Q3 and the second load R2 is powered. The second load R2 continues to consume the power from the secondary main feedback winding N S1 The current i o1 At the same time, the third capacitor Co1 supplies power to the first load R1.

[0069] In this stage, the secondary feedback winding N S2 The current direction and the secondary side main feedback winding N S1 The current direction is shown in FIG8 , and referring to FIG7 , the secondary side main feedback winding N S1 The current i o1The direction starts to reverse from time t8; the secondary feedback winding N S2 The current i o2 Although it is still decreasing gradually, due to the secondary side main feedback winding N S1 The remaining energy flows into the secondary feedback winding N S2 The circuit charges the fourth capacitor Co2 and supplies power to the second load R2, so the current i o2 The slope of the decline is smaller than that of the [t7-t8] stage, and at t9 the current i o2 Dropped to 0.

[0070] In the eighth working mode [t9-t 10 ], at time t9, the first switch tube Q1 remains off, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned off; the secondary side secondary feedback winding N S2 The output current drops to 0 at time t9; referring to FIG6 , on the secondary side of the transformer T1 , the auxiliary power supply still has the third capacitor Co1 to supply power to the first load R1 ; the fourth capacitor Co2 to supply power to the second load R2 .

[0071] Therefore, we can get: to t 10 At this moment, a complete signal cycle ends. In the [t6-t7] stage, the first load R1 is powered by the third capacitor Co1, and the second load R2 is powered by the fourth capacitor Co2. In the [t7-t8] stage, the secondary side main feedback winding N S1 Power the first load R1 through the secondary feedback winding N S2 Power the second load R2; [t8-t9] stage, through the secondary side main feedback winding N S1 and the secondary feedback winding N S2 Power is supplied to the second load R2 together, and power is supplied to the first load R1 through the third capacitor Co1; [t9-t 10 ] stage, power is supplied to the first load R1 through the third capacitor Co1, and power is supplied to the second load R2 through the fourth capacitor Co2. During this period, the two currents on the secondary side of transformer T1 are evenly distributed, making the output voltages of both the master and slave paths relatively stable.

[0072] Furthermore, it can be seen that in the fifth working mode [t6-t7] stage, the second capacitor C2 transfers the leakage inductance energy absorbed in the previous stage to the primary secondary winding N through the first switch tube Q1. P2 Charging, where the leakage inductance energy absorbed by the second capacitor C2 in the previous stage is obtained by the leakage inductance Lr charging the second capacitor C2 through the diode D1 during the sixth working mode [t7-t8] stage in the previous signal cycle.

[0073] Referring to Figure 7, from t 11At the moment, the next signal cycle begins, and the working state of the auxiliary power supply in the next signal cycle is still as described in the fifth to eighth working modes.

[0074] Therefore, based on the switching of the operating modes of the auxiliary power supply under two different load conditions, light and heavy, it can be seen that the dual-path flyback DC / DC auxiliary power supply with low cross-regulation and lossless absorption of this embodiment, on the one hand, adopts a primary-side leakage inductance lossless absorption circuit. By directly winding the winding on the primary side of the transformer and adding a clamping diode, the leakage inductance spike can be effectively suppressed, thereby avoiding the power loss problem caused by the traditional RCD absorption circuit, reducing circuit loss and improving power supply efficiency. In addition, by directly winding the winding, the switch tube and the high-side switch tube drive circuit in the traditional RCD absorption circuit are eliminated, thereby reducing cost and design difficulty and reducing the size of the power supply board. On the other hand, by controlling the two synchronous rectifier tubes on the secondary side of the transformer, even energy distribution can be achieved, so that the output voltage of the slave path can adapt to change regardless of whether the main path output is heavy or light, avoiding the phenomenon of sudden increase or decrease in the output voltage, improving the stability of the output voltage, and reducing the cross-regulation rate of the power supply.

[0075] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A dual-path flyback DCDC auxiliary power supply with low cross-regulation rate and lossless absorption, characterized in that: The auxiliary power supply includes a DC power supply Uin, a first capacitor C1, a primary leakage inductance lossless absorption circuit, a transformer T1 and a secondary synchronous rectification current balancing circuit connected in sequence; The transformer T1 includes a primary main winding N P1 、Primary secondary winding N P2 , secondary side main feedback winding N S1 , secondary side secondary feedback winding N S2 ; The primary leakage inductance lossless absorption circuit includes a first switch tube Q1, a diode D1, a second capacitor C2, a leakage inductance Lr, an excitation inductance Lm, a primary secondary winding N P2 The secondary synchronous rectification current balancing circuit includes a second synchronous rectifier Q2, a third synchronous rectifier Q3, a third capacitor Co1, a fourth capacitor Co2, a first load R1 and a second load R2; The positive electrode of the first capacitor C1 is connected to the positive electrode of the DC power supply Uin, the cathode of the diode D1, and one end of the leakage inductor Lr, respectively; the negative electrode of the first capacitor C1 is connected to the negative electrode of the DC power supply Uin, the source of the first switch tube Q1, the primary secondary winding N P2 The same-name end of the primary and secondary windings N P2 The opposite ends are connected to the anode of the diode D1 and the cathode of the second capacitor C2 respectively; the primary main winding N P1 The same-name ends of the primary winding N are connected to the other end of the leakage inductance Lr and one end of the excitation inductance Lm respectively; P1 The opposite ends of the transistors are respectively connected to the other end of the excitation inductor Lm, the positive electrode of the second capacitor C2, and the drain of the first switch tube Q1; The secondary side main feedback winding N S1 The same-named ends are respectively connected to the negative electrode of the third capacitor Co1, the negative electrode of the first load R1, the negative electrode of the fourth capacitor Co2, and the negative electrode of the second load R2, and the secondary side main feedback winding N S1 The opposite end is connected to the source of the second synchronous rectifier Q2, and the secondary feedback winding N S2 The same-named ends are respectively connected to the drain of the second synchronous rectifier Q2, the positive electrode of the third capacitor Co1, and the positive electrode of the first load R1, and the secondary feedback winding N S2 The opposite end of the auxiliary power supply is connected to the source of the third synchronous rectifier Q3, and the drain of the third synchronous rectifier Q3 is connected to the positive electrode of the fourth capacitor Co2 and the positive electrode of the second load R2 respectively; the main output of the auxiliary power supply is connected to the first load R1, and the slave output of the auxiliary power supply is connected to the second load R2; The auxiliary power supply operates in DCM mode, the main output of the auxiliary power supply is heavy-loaded, and the slave output of the auxiliary power supply is light-loaded; When the main output of the auxiliary power supply is heavily loaded and the slave output of the auxiliary power supply is lightly loaded, the auxiliary power supply includes four working modes in sequence within a complete signal cycle: a first working mode, a second working mode, a third working mode, and a fourth working mode; In the second working mode [t1-t2], at time t1, the first switch tube Q1 is turned off, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned on; the primary side secondary winding N P2 The energy is fed back to the first capacitor C1 through the diode D1; the leakage inductor Lr charges the second capacitor C2 through the diode D1; the excitation inductor Lm transfers the energy to the secondary side main feedback winding N S1 and the secondary feedback winding N S2 ; Secondary side main feedback winding N S1 The second synchronous rectifier Q2 is used to supply the The three capacitors Co1 are charged and supply power to the first load R1; Secondary feedback winding N S2 Through the second synchronous rectifier Q2, the third synchronous rectifier Q3, the secondary main feedback winding N S1 The fourth capacitor Co2 is charged and the second load R2 is powered.

2. The dual-path flyback DCDC auxiliary power supply with low cross-regulation rate and lossless absorption according to claim 1, characterized in that: The auxiliary power supply operates in DCM mode, the main output of the auxiliary power supply is heavily loaded, and the secondary output of the auxiliary power supply is lightly loaded, or the main output of the auxiliary power supply is lightly loaded, and the secondary output of the auxiliary power supply is heavily loaded; When the main output of the auxiliary power supply is heavily loaded and the slave output of the auxiliary power supply is lightly loaded, the auxiliary power supply includes four working modes in sequence within a complete signal cycle: a first working mode, a second working mode, a third working mode, and a fourth working mode; When the main output of the auxiliary power supply is lightly loaded and the slave output of the auxiliary power supply is heavily loaded, the auxiliary power supply includes four working modes in sequence within a complete signal cycle: a fifth working mode, a sixth working mode, a seventh working mode, and an eighth working mode; In the sixth working mode [t7-t8], at time t7, the first switch tube Q1 is turned off, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned on; the primary side secondary winding N P2 The energy is fed back to the first capacitor C1 through the diode D1; the leakage inductor Lr charges the second capacitor C2 through the diode D1; the excitation inductor Lm transfers the energy to the secondary side main feedback winding N S1 and the secondary feedback winding N S2 ; Secondary side main feedback winding N S1 The third capacitor Co1 is charged through the second synchronous rectifier Q2 and the first load R1 is powered; Secondary feedback winding N S2 Through the second synchronous rectifier Q2, the third synchronous rectifier Q3, the secondary main feedback winding N S1 The fourth capacitor Co2 is charged and the second load R2 is powered.

3. The dual-path flyback DCDC auxiliary power supply with low cross-regulation rate and lossless absorption according to claim 1, characterized in that: In the first working mode [t0-t1], at time t0, the first switch tube Q1 is turned on, and the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned off; The DC power supply Uin is filtered by the first capacitor C1 and then charges the excitation inductor Lm and the leakage inductor Lr through the first switch tube Q1; the second capacitor C2 absorbs the leakage inductance energy and charges the primary secondary winding N through the first switch tube Q1. P2 Charging; the third capacitor Co1 supplies power to the first load R1; the fourth capacitor Co2 supplies power to the second load R2.

4. The dual-path flyback DCDC auxiliary power supply with low cross-regulation rate and lossless absorption according to claim 1, characterized in that: In the third working mode [t2-t3], at time t2, the first switch tube Q1 remains turned off, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 remain turned on; the secondary side secondary feedback winding N S2 The output current drops to 0 at time t2 and starts to flow in the reverse direction. S2 The remaining energy and the secondary main feedback winding N S1 The third capacitor Co1 is charged through the second synchronous rectifier Q2 and supplies power to the first load R1; the fourth capacitor Co2 supplies power to the second load R2 supplies power.

5. The dual-path flyback DCDC auxiliary power supply with low cross-regulation rate and lossless absorption according to claim 1, characterized in that: In the fourth working mode [t3-t4], at time t3, the first switch tube Q1 remains turned off, and the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned off; Secondary side main feedback winding N S1 The output current drops to 0 at time t3; the third capacitor Co1 supplies power to the first load R1; and the fourth capacitor Co2 supplies power to the second load R2.

6. The dual-path flyback DCDC auxiliary power supply with low cross-regulation rate and lossless absorption according to claim 2, characterized in that: In the fifth working mode [t6-t7], at time t6, the first switch tube Q1 is turned on, and the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned off; The DC power supply Uin is filtered by the first capacitor C1 and then charges the excitation inductor Lm and the leakage inductor Lr through the first switch tube Q1; the second capacitor C2 absorbs the leakage inductance energy and charges the primary secondary winding N through the first switch tube Q1. P2 Charging; the third capacitor Co1 supplies power to the first load R1; the fourth capacitor Co2 supplies power to the second load R2.

7. The dual-path flyback DCDC auxiliary power supply with low cross-regulation rate and lossless absorption according to claim 2, characterized in that: In the seventh working mode [t8-t9], at time t8, the first switch tube Q1 remains turned off, the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 remain turned on; the secondary side main feedback winding N S1 The output current drops to 0 at time t8 and starts to flow in the reverse direction. S1 The remaining energy and the secondary feedback winding N S2 The fourth capacitor Co2 is charged through the third synchronous rectifier Q3 and the second load R2 is powered; the third capacitor Co1 powers the first load R1.

8. The dual-path flyback DCDC auxiliary power supply with low cross-regulation rate and lossless absorption according to claim 2, characterized in that: In the eighth working mode [t9-t 10 ], at time t9, the first switch tube Q1 remains turned off, and the second synchronous rectifier tube Q2 and the third synchronous rectifier tube Q3 are turned off; Secondary side main feedback winding N S1 The output current drops to 0 at time t9; the third capacitor Co1 supplies power to the first load R1; and the fourth capacitor Co2 supplies power to the second load R2.

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