A bipolar output cross regulation improvement circuit

Abstract

A bipolar output cross regulation improvement circuit, the circuit comprises a bipolar output double-tube flyback converter, a cross regulation capacitor C p The bipolar output double-tube flyback converter comprises a DC input source u in , a power switch S1, a power switch S2, an excitation inductor L m , a transformer T, a clamping diode D 1p , a clamping diode D 2p , a diode D1, a diode D2, an output capacitor C 1, an output capacitor C 2; compared with the traditional bipolar output double-tube flyback converter, the present application can realize the improvement of cross regulation by only adding a cross regulation capacitor, without using a complex sampling and control algorithm, the implementation is simple, and the control and driving mode of the original circuit is not affected, the problem of uneven energy distribution caused by load disturbance is solved, the self-voltage balancing effect of the bipolar output circuit is realized, the voltage deviation is reduced, and it is suitable for occasions requiring bipolar voltage power supply.

Description

Technical Field

[0001] This invention relates to a bipolar output circuit, specifically to a bipolar output crossover regulation improvement circuit. Background Technology

[0002] With the development of network technology, electronic devices are becoming increasingly information-based, intelligent, and complex. Various electronic products typically require stable power supplies, making power supply stability and reliability paramount for their proper functioning. Bipolar power supply exhibits inherent advantages in many aspects, including the efficiency of integrating new energy sources such as photovoltaics and fuel cells, the power supply efficiency of data centers and server rooms, the flexibility of load connection, power supply reliability, and system grounding.

[0003] However, traditional bipolar flyback converters suffer from cross-regulation issues, which can lead to voltage imbalances in their output voltage when the load is inconsistent. Many factors influence cross-regulation, including transformer leakage inductance, converter front-end clamping voltage, and output load imbalance. The cross-regulation problem of bipolar output converters has long been a challenging and hot research topic for power supply engineers.

[0004] Currently, measures to improve cross-regulation mainly fall into two categories: control and circuit topology. For example, patent document CN105322798B discloses a "multi-output flyback converter." This converter sets up a voltage-type negative feedback loop in the output circuit. The energy transfer is controlled through the voltage negative feedback loop and PWM control, ensuring high stability of the auxiliary output voltage. Compared to multi-output flyback converters that use two-stage power converters for voltage regulation, this converter can directly supply power to the load from the transformer through a rectifier switch, eliminating the need for a second-stage conversion. Therefore, the auxiliary output efficiency of this converter is high. However, the added switch in the auxiliary circuit increases the difficulty of timing control.

[0005] Patent application CN114679065A discloses a "high-efficiency, low-cross-regulation multi-output power supply." This converter, based on a flyback topology, connects each output of a multi-output DC / DC power supply to a synchronous rectification and output regulation circuit. The output voltage is then adjusted secondaryly by this circuit. Simultaneously, the freewheeling diodes on the secondary side of the multi-output DC / DC power supply are replaced with low-loss MOSFETs, thereby reducing output losses and improving the cross-regulation of the multi-output power supply. This solves the technical problems of numerous circuit components and complex control in existing multi-output power supply cross-regulation optimization schemes. However, replacing the rectifier diodes with two common-source MOSFETs increases circuit losses, resulting in low power transmission efficiency. Summary of the Invention

[0006] To address the issue of output voltage deviation in traditional bipolar output two-transistor flyback converters due to load disturbances, this invention proposes a bipolar output crossover regulation improvement circuit based on the traditional bipolar output two-transistor flyback converter. This circuit comprises a basic bipolar output two-transistor flyback converter and a bridging capacitor. Compared to the traditional bipolar output two-transistor flyback converter, the crossover regulation is improved simply by adding the bridging capacitor. The implementation is simple and does not affect the control and drive methods of the original circuit.

[0007] The technical solution adopted in this invention is as follows:

[0008] A bipolar output crossover regulation improvement circuit includes a bipolar output dual-transistor flyback converter and a crossover adjustment capacitor C. p ;

[0009] The bipolar output dual-transistor flyback converter includes a DC input source u in Power switch S1, power switch S2, magnetizing inductor L m Transformer T, Clamping diode D 1p Clamping diode D 2p Diodes D1 and D2, output capacitor C1, and output capacitor C2; their connection configuration is as follows:

[0010] Input power u in The positive terminals are respectively connected to clamping diode D. 1p The cathode and the drain of power switch S1;

[0011] The source of power switch S1 is connected to clamping diode D. 2p Cathode, magnetizing inductor L m The upper end of the transformer T, the primary winding L p The upper part

[0012] Magnetizing inductance L m The lower ends are respectively connected to clamping diodes D 1p The anode of the power switch S2, the drain of the power switch S2, and the primary winding L of the transformer T. p The lower end;

[0013] Clamping diode D 2p The anode of the circuit and the source of the power switch S2 are both connected to the input power supply u. in The negative electrode;

[0014] The secondary winding L of transformer T s1 The upper end is connected to the anode of diode D1, the cathode of diode D1 is connected to the upper end of output capacitor C1, and the lower end of output capacitor C1 is connected to the secondary winding L of transformer T. s1 The lower end;

[0015] The secondary winding L of transformer T s2 The upper end is connected to the anode of diode D2, the cathode of diode D2 is connected to the upper end of output capacitor C2, and the lower end of output capacitor C2 is connected to the secondary winding L of transformer T. s2 The lower end;

[0016] The lower end of output capacitor C1 is connected to the upper end of output capacitor C2;

[0017] bridging capacitor C p The upper end is connected to the secondary winding L of transformer T. s1 The upper end is connected to a bridging capacitor C. p The lower end is connected to the secondary winding L of transformer T. s2 The upper end connection;

[0018] Load R L1 The two ends are connected to the upper and lower ends of the output capacitor C1, respectively;

[0019] Load R L2 The two ends are connected to the upper and lower ends of the output capacitor C2, respectively.

[0020] The gates of power switch S1 and power switch S2 are respectively connected to their respective controllers, and their duty cycles vary between 0 and 0.5 and are in phase.

[0021] When power switches S1 and S2 are turned on, diodes D1, D2, and clamping diode D... 1p Clamping diode D 2p Off, input voltage u in Added to the primary winding L of transformer T p Above, excitation inductor L m As the current increases, the energy stored in the transformer increases, and this energy is transferred to the secondary winding of transformer T. Diodes D1 and D2 are cut off due to reverse voltage, and the secondary winding of transformer T is connected with a bridging capacitor C. p Charging, output capacitor C1 is the load R L1 Power supply, output capacitor C2 is the load R L2 powered by.

[0022] When power switches S1 and S2 are turned off, clamping diode D 1p Clamping diode D 2p Turn on and clamp the voltage on the power switch to the input source voltage u. in Complete the clamping of diode D 1p Clamping diode D 2pTurn off. Simultaneously, diodes D1 and D2 remain conducting during the power switch turn-off phase, causing the current in the transformer secondary winding to decrease, and the regulating capacitor C connected across it... p Discharge through diode D1, secondary coil L s2 The output capacitors C1 and C2 are charged by discharging through diode D2.

[0023] Throughout the entire switching cycle, according to the inductor volt-second balance principle, the average voltage of the transformer secondary winding is 0, determined by L. s1 →C p →L s2 →C2→L s1 Using the KVL principle for a loop, the capacitance C can be obtained. p voltage u cp Equal to output voltage u o2 During the switch-off period, diode D1 conducts, and the transformer secondary winding L... s1 and the bridging capacitor C p Through loop L s1 (C p →D1→C1→L s1 (C p Charging capacitor C1; capacitor C p Since diode D1 is connected in parallel with output capacitor C1, capacitor C... p voltage u cp Equal to output voltage u o1 When capacitor C p When the voltage is large enough, the output voltages of the transformer secondary winding and the bipolar unit are equal, realizing automatic voltage equalization of the bipolar output flyback converter and improving the cross-regulation rate of the bipolar output.

[0024] The present invention provides a bipolar output crossover regulation improvement circuit, the technical effects of which are as follows:

[0025] 1) The present invention improves the circuit by connecting a capacitor across the anode side of the bipolar output winding diode, which greatly reduces the voltage imbalance problem caused by the cross regulation rate in the traditional flyback converter when bipolar output, realizes the automatic voltage equalization effect of the bipolar output circuit, and reduces voltage deviation.

[0026] 2) The circuit topology of the improved circuit of the present invention is simple. It only uses a single cross-connected adjustment capacitor to improve the cross regulation rate without changing the original converter's control drive mode, and does not require complex sampling and control algorithms.

[0027] 3) The improved circuit of this invention solves the problem of uneven energy distribution caused by load disturbance. It achieves the self-equalizing voltage effect of the bipolar output circuit, reduces voltage deviation, and is suitable for applications requiring bipolar voltage power supply. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0029] Figure 1 This is a schematic diagram of a traditional bipolar output dual-transistor flyback converter circuit.

[0030] Figure 2 This is a simulation diagram of the output voltage waveform of a basic dual-winding output dual-transistor flyback converter under unbalanced two-way loads;

[0031] Figure 3 This is the circuit schematic diagram of the present invention;

[0032] Figure 4 This is a simulation diagram of the output voltage waveform under two-way load imbalance using the present invention.

[0033] in: Figure 2 , Figure 4 All operating conditions are the same. Detailed Implementation

[0034] Depend on Figure 1 It can be seen that the traditional bipolar output dual-transistor flyback converter contains two secondary windings. Due to the problem of cross regulation, the bipolar output voltage will have a voltage deviation when the load is unbalanced, and it is difficult to keep the dual output voltages consistent.

[0035] Depend on Figure 2 It can be seen that the output voltage of a traditional bipolar output dual-transistor flyback converter under unbalanced load conditions has a voltage difference of 47.4V, which is difficult to meet the output voltage requirements under unbalanced load conditions.

[0036] like Figure 3 As shown, a bipolar output crossover regulation improvement circuit includes a basic bipolar output two-transistor flyback converter and a crossover adjustment capacitor, wherein:

[0037] A basic bipolar output two-transistor flyback converter includes: a DC input source u in One upper power switch S1, one lower power switch S2, and magnetizing inductor L m Transformer T, Clamping diode D 1p Clamping diode D 2p Diodes D1 and D2, output capacitor C1, and output capacitor C2; their connection configuration is as follows:

[0038] Clamping diode D 1p The cathode and the drain of the upper power switch S1 are simultaneously connected to the input power supply u. in The positive terminal. Magnetizing inductor L m The upper end and the primary winding L of transformer T pThe upper end and the source of the upper power switch S1 are simultaneously connected to the input clamping diode D. 2p The cathode. Magnetizing inductance L m The lower end and the primary winding L of transformer T p The lower end and the drain of the lower power switch S2 are respectively connected to clamping diode D. 1p The anode. Clamping diode D 2p The anode and the source of the lower power switch S1 are simultaneously connected to the input power supply u. in The negative terminal. The gates of the upper power switch S1 and the lower power switch S2 are respectively connected to their respective controllers. The secondary winding L of transformer T s1 The upper end is connected to the anode of diode D1, the cathode of diode D1 is connected to the upper end of output capacitor C1, and the lower end of output capacitor C1 is connected to the secondary winding L of transformer T. s1 The lower end. The secondary winding L of transformer T. s2 The upper end is connected to the anode of diode D2, the cathode of diode D2 is connected to the upper end of output capacitor C2, and the lower end of output capacitor C2 is connected to the secondary winding L of transformer T. s2 The lower end of output capacitor C1 is connected to the upper end of output capacitor C2.

[0039] bridging capacitor C p The upper end is connected to the secondary winding L of transformer T. s1 The upper end is connected to a bridging capacitor C. p The lower end is connected to the secondary winding L of transformer T. s2 The upper end connection.

[0040] Load R L1 The two ends are connected to the upper and lower ends of the output capacitor C1, respectively, and the load R L2 The two ends are connected to the upper and lower ends of the output capacitor C2, respectively.

[0041] The gates of the upper power switch S1 and the lower power switch S2 are connected to their respective controllers, and their duty cycles can vary between 0 and 0.5 and are in phase.

[0042] When the upper power switch S1 and the lower power switch S2 are turned on, diodes D1, D2, and clamping diode D... 1p Clamping diode D 2p Off, input voltage u in Added to the primary winding L of transformer T p Above, excitation inductor L m As the current increases, the energy stored in the transformer increases, and this energy is transferred to the secondary winding of transformer T. Diodes D1 and D2 are cut off due to reverse voltage, and the secondary winding of transformer T is connected with a bridging capacitor C. p Charging, output capacitor C2 is the load RL2 Power supply, output capacitor C1 is the load R L1 powered by.

[0043] When the upper power switch S1 and the lower power switch S2 are turned off, the clamping diode D... 1p Clamping diode D 2p Turn on and clamp the voltage on the power switch to the input source voltage u. in Complete the clamping of diode D 1p Clamping diode D 2p Turn off. Simultaneously, diodes D1 and D2 remain conducting during the power switch turn-off phase, causing the current in the transformer secondary winding to decrease, and the regulating capacitor C connected across it... p Discharge through diode D1, secondary coil L s2 The output capacitors C1 and C2 are charged by discharging through diode D2.

[0044] Throughout the entire switching cycle, according to the inductor volt-second balance principle, the average voltage of the transformer secondary coil is 0, determined by L. s1 →C p →L s2 →C2→L s1 The capacitance C can be obtained from the KVL principle of the circuit. p voltage u cp Equal to output voltage u o2 During the switch-off period, diode D1 conducts, and the transformer secondary winding L... s1 and the bridging capacitor C p Through loop L s1 (C p →D1→C1→L s1 (C p Charging capacitor C1; capacitor C p Since diode D1 is connected in parallel with output capacitor C1, capacitor C... p voltage u cp Equal to output voltage u o1 When capacitor C p When the voltage is large enough, the output voltages of the transformer secondary winding and the bipolar unit are equal, realizing automatic voltage equalization of the bipolar output flyback converter and improving the cross-regulation rate of the bipolar output.

[0045] Depend on Figure 4 As can be seen, when using this invention, the output voltage difference under unbalanced loads is only 0.3V, which is significantly reduced compared to the output voltage difference of traditional bipolar output dual-transistor flyback converters. Under unbalanced load conditions, the circuit itself achieves self-equalization of output voltage, effectively improving the problem of large output voltage deviation between the two channels caused by the cross-regulation rate in traditional bipolar output dual-transistor flyback converters.

Claims

1. A bipolar output crossover regulation improvement circuit, characterized in that: The circuit includes a bipolar output dual-transistor flyback converter and a bridging capacitor. C p ; The bipolar output dual-transistor flyback converter includes a DC input source. u in Power switch S1, power switch S2, magnetizing inductor L m Transformer T, Clamping diode D 1p Clamping diode D 2p Diode D1, Diode D2, Output Capacitor C 1. Output capacitor C 2; Its connection form is as follows: DC input source u in The positive terminals are respectively connected to clamping diode D. 1p The cathode and the drain of power switch S1; The source of power switch S1 is connected to clamping diode D. 2p Cathode, magnetizing inductor L m The upper end of the primary winding of transformer T L p The upper end; Magnetizing inductor L m The lower ends are respectively connected to clamping diodes D 1p The anode of the power switch S2, the drain of the power switch S2, and the primary winding of the transformer T. L p The lower end; Clamping diode D 2p The anode of the circuit and the source of the power switch S2 are both connected to a DC input source. u in The negative electrode; The secondary winding of transformer T L s1 The upper end is connected to the anode of diode D1, and the cathode of diode D1 is connected to the output capacitor. C The upper end of 1, the output capacitor C The lower end of 1 is connected to the secondary winding of transformer T. L s1 The lower end; The secondary winding of transformer T L s2 The upper end is connected to the anode of diode D2, and the cathode of diode D2 is connected to the output capacitor. C The upper end of 2, the output capacitor C The lower end of 2 is connected to the secondary winding of transformer T. L s2 The lower end; Output capacitor C The lower end of 1 is connected to the output capacitor. C 2. Connect the upper end; bridging capacitor C p The upper end is connected to the secondary winding of transformer T. L s1 The upper end is connected to a bridging capacitor. C p The lower end is connected to the secondary winding of transformer T. L s2 The upper end connection; load R L1 The two ends are respectively connected to the output capacitor C The upper end of 1, the output capacitor C Connect the lower end of 1; load R L2 The two ends are respectively connected to the output capacitor C 2's upper end, output capacitor C Connect the lower end of 2; Throughout the entire switching cycle, the secondary winding of transformer T L s1 , L s2 The average voltage is 0, from L s1 → C p → L s2 → C 2→ L s1 Based on the KVL principle of the loop, the bridging adjustment capacitor can be obtained. C p voltage u cp Equal to output capacitance C 2 Output voltage at both ends u o2 During the switch-off period, diode D1 is turned on, and the secondary winding of transformer T... L s1 and bridging capacitor C p pass L s1 ( C p →D1→ C 1→ L s1 ( C p The circuit leads to the output capacitor. C 1. Charging; bridging adjustment capacitor C p Through diode D1 and output capacitor C 1. Parallel connection, therefore a bridging capacitor is needed. C p voltage u cp Equal to output capacitance C 1. Output voltage at both ends u o1 When a regulating capacitor is connected across it C p When large enough, the secondary winding of transformer T L s1 , L s2 and output capacitor C 1. Output capacitor C The output voltages at both ends are equal, realizing automatic voltage equalization of the bipolar output dual-transistor flyback converter and improving the cross-regulation rate of the bipolar output.

2. The bipolar output crossover regulation improvement circuit according to claim 1, characterized in that: The gates of power switch S1 and power switch S2 are respectively connected to their respective controllers, and their duty cycles vary between 0 and 0.5 and are in phase.

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