Voltage stabilization control circuit applied to multi-path output flyback topology

Abstract

The invention discloses a voltage stabilization control circuit applied to multi-path output flyback topology, which relates to the field of multi-path output auxiliary power supply, and comprises a transformer, a primary side driving switch circuit, a feedback control loop and a plurality of groups of secondary side output loops and load simulation circuits, a load simulation circuit composed of a diode, a capacitor and a resistor is introduced into a key secondary output loop, a feedback sampling point is moved to the capacitor, and the time constant of the load simulation circuit is matched with the load time constant of each output loop through fine design. By means of the design, the controller can be intelligently guided to adjust the duty ratio, it is ensured that under all load conditions, output voltages of all paths can be kept above rated values, system downtime is fundamentally avoided, and the reliability of the system is improved. According to the circuit, the reliability and the load adaptability of the power supply are remarkably improved with extremely low cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of auxiliary power supply with multiple outputs, in particular to a voltage stabilizing control circuit applied to a multiple output flyback topology. BACKGROUND

[0002] Generally, for a multiple output flyback topology, the output of each path corresponds to the winding of each transformer. Since the transformer is a non-ideal transformer, there is leakage inductance between each set of coils. The existence of leakage inductance makes the cross regulation between each path very poor, especially when the voltage stabilizing loop is under zero load and the non-voltage stabilizing loop is under full load. At this time, the voltage of the non-voltage stabilizing loop will drop below the error voltage, which will cause the entire system to malfunction or even restart. SUMMARY

[0003] The present application aims to provide a voltage stabilizing control circuit applied to a multiple output flyback topology to solve the problems raised in the background.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical solution: a voltage stabilizing control circuit applied to a multiple output flyback topology, comprising a transformer T1, a primary side driving switch circuit, a feedback control loop and a plurality of secondary side output circuits, further comprising a load simulation circuit, the input end of the load simulation circuit is coupled to one of the secondary side output circuits, and the output end is connected to the ground reference of the corresponding secondary side output circuit, and the voltage sampling point of the feedback control loop is connected to the load simulation circuit.

[0005] The load simulation circuit is configured to generate an analog load signal according to the voltage change of the secondary side output circuit and apply the signal to the voltage sampling point of the feedback control loop, so that the feedback control loop adjusts the duty cycle of the primary side driving switch circuit according to the load condition of the secondary side output circuit, thereby maintaining the voltage of all secondary side output circuits within a set range.

[0006] As a preferred embodiment, the load simulation circuit comprises a diode Ds, a polarized capacitor Cs and a resistor Rs, the anode of the diode Ds is coupled to the secondary side output circuit, the polarized capacitor Cs and the resistor Rs are connected in parallel, one end of which is connected to the cathode of the diode Ds, and the other end is connected to the ground reference of the corresponding secondary side output circuit, and the voltage sampling point of the feedback control loop is connected to the cathode of the diode Ds.

[0007] As preferred, the feedback control loop comprises an optocoupler, a voltage dividing and sampling unit and a voltage stabilizing unit, the voltage dividing and sampling unit comprises a resistor R2 and a resistor R3, the resistor R2 and the resistor R3 are connected in series, the cathode of the diode Ds is connected between the resistor R2 and the resistor R3, the other end of the resistor R2 is connected to the anode of the optocoupler, one end of the voltage stabilizing unit is connected to the cathode of the optocoupler, and the other end is grounded.

[0008] As preferred, the voltage stabilizing unit comprises a voltage stabilizing integrated component IC2 and a resistor R4, one end of the resistor R4 is connected to the resistor R3, and the other end is connected to the anode of the voltage stabilizing integrated component IC2, the cathode of the voltage stabilizing integrated component IC2 is connected to the cathode of the optocoupler.

[0009] As preferred, the secondary side output loop comprises a diode Dn, an inductor Ln, a polar capacitor Cn and a load RLn, the polar capacitor Cn and the load RLn are connected in parallel, the cathode of the diode Dn is connected to the polar capacitor Cn, the anode of the diode Dn is connected to the inductor Ln, the other end of the inductor Ln is connected to the polar capacitor Cn, and the anode of the diode Ds is connected between the inductor Ln and the polar capacitor Cn.

[0010] As preferred, the primary side drive switch circuit comprises a MOS tube Q1, a drive diode, a resistor R1 and a non-polar capacitor C3, the non-polar capacitor C3 and the resistor R1 are connected in parallel, and the cathode of the drive diode is connected to the non-polar capacitor C3 and the resistor R1, the anode of the drive diode is connected to the MOS tube Q1.

[0011] As preferred, the time constant of the polar capacitor Cs and the resistor Rs after taking values is of the same order of magnitude as the time constant of any one of the secondary side output loops under rated load.

[0012] As preferred, the ratio of the time constant of the polar capacitor Cs and the resistor Rs after taking values to the time constant of the secondary side output loop is between 0.2 and 5.

[0013] As preferred, the resistance value of the resistor Rs is set to be less than 100 milliwatts under the rated output voltage.

[0014] In summary, the application has the following advantages:

[0015] The application can make the power supply control system perceive the load change of the non-stabilized output loop by introducing a load simulation circuit composed of a diode, a capacitor and a resistor and taking the voltage as a feedback signal, the core of which is to dynamically simulate the load characteristics of the heavy load branch by designing the time constant to match the time constant of each output loop, thereby guiding the controller to timely increase the energy supply when the auxiliary road is heavy, fundamentally solving the problem of poor cross regulation caused by transformer leakage inductance, ensuring that all output branches can maintain stable voltage not lower than the rated value under severe load change at extremely low cost, effectively avoiding system downtime or restart, and significantly improving the reliability, load adaptability and cost-effectiveness of the power supply. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0017] Figure 1 It is a whole schematic diagram of the voltage stabilizing control circuit applied to the multi-output flyback topology of the present application.

[0018] Figure 2 It is a principle circuit diagram in the embodiment of the voltage stabilizing control circuit applied to the multi-output flyback topology of the present application.

[0019] Figure 3 It is a prior art design circuit diagram in the embodiment of the voltage stabilizing control circuit applied to the multi-output flyback topology of the present application. DETAILED DESCRIPTION

[0020] The present application will be further described in detail with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. The drawings are simplified schematic diagrams and only show the basic structure of the present application in a schematic manner.

[0021] In order to facilitate the understanding of the present application, the present application will be described more fully with reference to the related drawings, which show some embodiments of the present application. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0022] All features disclosed in this specification, and / or all elements of the methods disclosed, can be combined in any combination, provided that the features and / or method steps are not mutually inconsistent.

[0023] Any feature in the present specification, unless explicitly stated to the contrary, is intended to be an example of an equivalent or similar feature. In other words, in the context of this specification, the use of the word "example" to modify a feature, or the use of language such as "for example" or "e.g." in relation to a feature, means that the feature is an example of a generic type of that feature, and not an instance of that feature. Any feature disclosed in this specification, unless explicitly stated to the contrary, can be replaced by an equivalent or similar feature.

[0024] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can be direct connection, or indirect connection through intermediate medium, can be internal communication of at least two elements or interaction relationship between at least two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0025] Before introducing this embodiment, first explain the existing multi-channel flyback topology structure, reference Figure 2 , the problem of conventional design is plagued, in the circuit RL1, RL2, RL3 is variable load, because the three loads are from the control circuit, the load size change will be from even 0 load to the maximum load, usually the front end has LDO or buck circuit for its voltage stabilization, but usually LDO or BUCK circuit can not boost, assuming that the load RL1 is in sleep state, the load is close to zero, while RL2…RLn one or several roads are in the maximum load state, because the transformer is a non-ideal transformer, such as Figure 3 , the leakage inductance (L1\L2…Ln) of this kind causes the corresponding output voltage to be lower than the rated value, and once the voltage is lower than the rated value, it will cause the system to shut down or restart. If you want to solve this problem, the conventional method is to reduce the leakage inductance (L1\L2…Ln) of the transformer, but due to the physical properties, this leakage inductance cannot be infinitely close to 0, and the cost of changing this phenomenon is high, an improved voltage stabilizing circuit will solve this problem.

[0026] Please refer to Figure 1The application provides a voltage stabilizing control circuit applied to a multi-output flyback topology, which comprises a transformer T1, a primary side driving switch circuit, a feedback control loop, a plurality of groups of secondary side output loops and a load simulation circuit.

[0027] Specifically, the load simulation circuit comprises a diode Ds, a polar capacitor Cs and a resistor Rs, an anode of the diode Ds is coupled to the secondary side output loop, which is usually an output loop with the most dramatic load change or the most critical output loop, in the embodiment, the diode Ds is connected to the first secondary side output loop, the polar capacitor Cs and the resistor Rs are connected in parallel, one end of the polar capacitor Cs and the resistor Rs is connected to a cathode of the diode Ds, and the other end is connected to a ground reference corresponding to the secondary side output loop, and a voltage sampling point of the feedback control loop is connected to the cathode of the diode Ds.

[0028] The feedback control loop comprises an optocoupler, a resistor R2, a resistor R3, a voltage stabilizing integrated component IC2 and a resistor R4, wherein the voltage stabilizing integrated component IC2 can be TL431, the resistor R2 and the resistor R3 are connected in series, the cathode of the diode Ds is connected between the resistor R2 and the resistor R3, the other end of the resistor R2 is connected to an anode of the optocoupler, one end of the resistor R4 is connected to the resistor R3, and the other end is connected to an anode of the voltage stabilizing integrated component IC2, a cathode of the voltage stabilizing integrated component IC2 is connected to a cathode of the optocoupler, and an anode is grounded, and the other side of the optocoupler is connected to an offline controller, so that the voltage sampling point is moved to a positive electrode of the capacitor Cs.

[0029] The secondary side output loop comprises a diode Dn, an inductor Ln, a polar capacitor Cn and a load RLn, the polar capacitor Cn and the load RLn are connected in parallel, a cathode of the diode Dn is connected to the polar capacitor Cn, and an anode is connected to the inductor Ln, the other end of the inductor Ln is connected to the polar capacitor Cn, and an anode of the diode Ds is connected between the inductor Ln and the polar capacitor Cn.

[0030] The primary side drive switch circuit comprises a MOS tube Q1, a drive diode, a resistor R1 and an inorganic capacitor C3, the inorganic capacitor C3 is connected in parallel with the resistor R1, and the resistor R1 is connected with the cathode of the drive diode, the anode of the drive diode is connected with the MOS tube Q1, and the MOS tube Q1 is connected with an offline controller.

[0031] After the introduction of Ds and Cs, Rs, and the supply R2 and sampling R3 of the voltage stabilizing feedback circuit are connected to the positive electrode of Cs, under the condition that the time constant after ensuring the values of Cs and Rs and the time constant under the rated load of other loops are equivalent, the values are taken as 0.2-5 times, so that the V1\V2…Vn voltage will not be lower than the design value under any dynamic or static load, so that a stable voltage can be provided to the system in the later stage through the LDO or buck circuit. Since the time constant formed by the filtering capacitor and the load of each path is generally a value of one order of magnitude, that is, C1*RL1≈C2*RL2≈…≈Cn*RLn, since Rs is a dummy load, in order to avoid the increase of power consumption, the resistance value is usually large, and is usually designed to be within 100mW, and a smaller capacitor Cs is taken at the same time, and Cs*Rs is ensured to be close to C1*RL1, which can meet the design requirements.

[0032] The specific working process is as follows:

[0033] 1. When the load of the secondary side output loop is increased

[0034] The output voltage of the secondary side output loop has a downward trend, and since the anode of Ds is connected to the Vn output end, the anode voltage thereof also decreases, if the voltage V_Cs of the positive electrode of Cs is higher than (Vn-V_Ds) at this time, Ds is reverse-biased and cut off, and Cs can only be discharged slowly through the large resistor Rs, and V_Cs slowly decreases.

[0035] The feedback circuit samples the decrease of V_Cs, which is understood as that the voltage of the main feedback loop V1 is decreasing, so the duty cycle is increased, and more energy is injected into the transformer.

[0036] The increased energy is supplied to all secondary loops at the same time, and the heavily loaded secondary side output loop obtains the urgently needed energy, and the voltage thereof is maintained; and the voltage of the lightly loaded secondary side output loop rises due to the excess energy, but since the sampling point is not on the lightly loaded secondary side output loop, the rise cannot be “seen” and corrected by the feedback loop, and the system successfully avoids the voltage collapse of the Vn loop.

[0037] 2. When the load of the secondary side output loop is reduced

[0038] The secondary side output loop output voltage has a rising trend, the Ds anode voltage rises, when it is higher than (V_Cs + V_Ds), the Ds is turned on, the secondary side output loop charges the capacitor Cs, the V_Cs voltage rises, the feedback control loop samples the rise of V_Cs, and understands that the voltage of the main feedback loop V1 is too high, so the duty cycle is reduced, and the total energy transmission is reduced.

[0039] This action prevents the secondary side output loop voltage from rising sharply under light load, and also prevents the secondary side output loop voltage from being too high due to excessive energy under light load.

[0040] A specific example is as follows:

[0041] Design V1: 12V, 24W; V2: 12V, 12W; V3: 24V, 30W;

[0042] C1 uses 1000uF, C2 uses 470uF, C3 uses 270uF,

[0043] The equivalent RL1 is calculated to be 6Ω, RL2 is 12Ω, and RL3 is 19.2Ω,

[0044] C1*RL1=1000uF*6Ω=6000u,

[0045] C2*RL2=470uF*12Ω=5640u,

[0046] C3*RL3=270uF*19.2Ω=5184u.

[0047] In order to control the no-load power consumption and reduce system loss, Rs is taken as 3k, the loss is 48mW, the time constant is about equal to the time constant of other loops, taken as 5500u, Cs=1.8uF, taken Cs=2.2uF,

[0048] Rs*Cs=2.2uF*3kΩ=6600u is calculated from the new calculation, so the multiple relative to the average value is about 1.18.

[0049] In summary, the application introduces a load simulation circuit composed of a diode, a capacitor and a resistor, and uses the voltage as a feedback signal, so that the power control system can perceive the load change of the non-stabilized output loop. The core is to design the time constant to match the time constant of each output loop, so as to dynamically simulate the load characteristics of the heavy load branch, which leads the controller to increase the energy supply in time when the auxiliary road is heavy, and fundamentally solves the problem of poor cross-regulation caused by transformer leakage inductance. At a very low cost, it ensures that all output branches can maintain a stable voltage not lower than the rated value under severe load changes, effectively avoids system downtime or restart, and significantly improves the reliability, load adaptability and cost-effectiveness of the power supply.

[0050] The above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto. Any changes or replacements without creative labor should be covered within the protection scope of the application. Therefore, the protection scope of the application should be limited by the protection scope defined in the claims.

Claims

1. A voltage regulator control circuit applied to a multi-output flyback topology, comprising a transformer (T1), a primary-side drive switching circuit, a feedback control loop, and several sets of secondary-side output loops, characterized in that: It also includes a load simulation circuit, the input of which is coupled to one of the secondary-side output circuits, the output of which is connected to the ground reference corresponding to the secondary-side output circuit, and the voltage sampling point of the feedback control circuit is connected to the load simulation circuit. The load simulation circuit is configured to generate a simulated load signal based on the voltage change of the secondary output circuit, and apply the signal to the voltage sampling point of the feedback control circuit, so that the feedback control circuit adjusts the duty cycle of the primary drive switch circuit according to the load condition of the secondary output circuit, thereby maintaining the voltage of all secondary output circuits within a set range.

2. The voltage regulation control circuit applied to a multi-output flyback topology according to claim 1, characterized in that: The load simulation circuit includes a diode (Ds), a polarized capacitor (Cs), and a resistor (Rs). The anode of the diode (Ds) is coupled to the secondary output circuit. One end of the polarized capacitor (Cs) and the resistor (Rs) are connected in parallel to the cathode of the diode (Ds), and the other end is connected to the ground reference corresponding to the secondary output circuit. The voltage sampling point of the feedback control circuit is connected to the cathode of the diode (Ds).

3. The voltage regulation control circuit applied to a multi-output flyback topology according to claim 2, characterized in that: The feedback control loop includes an optocoupler, a voltage divider sampling unit, and a voltage regulator unit. The voltage divider sampling unit includes a resistor (R2) and a resistor (R3) connected in series. The cathode of the diode (Ds) is connected between the resistor (R2) and the resistor (R3). The other end of the resistor (R2) is connected to the anode of the optocoupler. One end of the voltage regulator unit is connected to the cathode of the optocoupler, and the other end is grounded.

4. A voltage regulation control circuit for a multi-output flyback topology according to claim 3, characterized in that: The voltage regulator unit includes a voltage regulator integrated component (IC2) and a resistor (R4). One end of the resistor (R4) is connected to the resistor (R3), and the other end is connected to the anode of the voltage regulator integrated component (IC2). The cathode of the voltage regulator integrated component (IC2) is connected to the cathode of the optocoupler.

5. A voltage regulation control circuit for a multi-output flyback topology according to claim 4, characterized in that: The secondary output circuit includes a diode (Dn), an inductor (Ln), a polarized capacitor (Cn), and a load (RLn). The polarized capacitor (Cn) and the load (RLn) are connected in parallel. The cathode of the diode (Dn) is connected to the polarized capacitor (Cn), and the anode is connected to the inductor (Ln). The other end of the inductor (Ln) is connected to the polarized capacitor (Cn). The anode of the diode (Ds) is connected between the inductor (Ln) and the polarized capacitor (Cn).

6. A voltage regulation control circuit for a multi-output flyback topology according to claim 5, characterized in that: The primary-side drive switching circuit includes a MOSFET (Q1), a drive diode, a resistor (R1), and an inorganic capacitor (C3). The inorganic capacitor (C3) is connected in parallel with the resistor (R1) and then connected to the cathode of the drive diode. The anode of the drive diode is connected to the MOSFET (Q1).

7. A voltage regulation control circuit applied to a multi-output flyback topology according to claim 2, characterized in that: The time constants of the polarized capacitor (Cs) and the resistor (Rs) are approximately on the same order of magnitude as the time constants of any of the secondary output circuits under rated load.

8. A voltage regulation control circuit for a multi-output flyback topology according to claim 7, characterized in that: The ratio of the time constant of the polarized capacitor (Cs) and the resistor (Rs) to the time constant of the secondary output circuit is between 0.2 and 5.

9. A voltage regulation control circuit applied to a multi-output flyback topology according to claim 8, characterized in that: The resistance value of the resistor (Rs) is set such that its power consumption at the rated output voltage is less than 100 milliwatts.

Images