An adaptive output power switching circuit structure

Abstract

The utility model relates to a kind of self-adapting output power supply switching circuit structure, applied to the circuit of dual power supply, first power supply circuit is connected with first feedback control loop and loop stable control circuit, second power supply circuit is connected with second feedback control loop;The output end of first power supply circuit and second power supply circuit is connected to common output end in parallel;Loop stable control circuit passes through the conduction and cut-off of control switch device to dynamically adjust the reference voltage of first power supply feedback loop, so that it can actively, stably enter standby state when needed, to avoid the loop conflict when dual power supply is in parallel.The circuit structure of the utility model is accurately sampled and level conversion by commonly used electronic components, converts the working state of power supply into linear regulation to reference voltage, realizes the seamless switching of fast, smooth between two power supplies.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit technology, and in particular to an adaptive output power switching circuit structure. Background Technology

[0002] In modern electronic equipment power supply systems, in order to ensure uninterrupted operation and improve reliability, a dual power supply redundancy backup design is often adopted. However, it is difficult for the two power supplies to be completely identical. Therefore, when the voltage of one power supply is higher than that of the other, it will affect the feedback loop of that power supply and cause output instability.

[0003] Currently, a common technical solution for parallel output of AC and DC dual power supplies is to add diodes for isolation at the output terminals of each power supply, and then connect them in parallel to the load, so as not to affect their respective voltage loops. However, this design is inefficient and has high losses. Diodes have an inherent forward voltage drop when conducting (typically 0.3V~0.7V), and under high current load conditions, the power loss on the diode (P = V) is significant. f The effect of ×I is very significant, causing severe diode overheating and affecting the overall efficiency of the device. Furthermore, in dual-power supply scenarios, the industry typically uses an AC-side priority approach, adjusting the output voltage of one side to be 0.5V~1V higher than the other. When both power supplies operate simultaneously, the power supply with the higher output voltage will bear the entire load current, while the power supply with the lower output voltage remains unloaded, thus achieving priority control. However, the feedback loop of the unloaded low-voltage power supply will continuously attempt to raise its own output voltage to carry the load, which conflicts with the high-voltage side loop, easily causing system oscillation, resulting in large output voltage ripple and decreased stability.

[0004] Therefore, there is an urgent need for a new circuit design scheme that can effectively solve the problem of dual power supply loop conflict and achieve fast, smooth, and seamless switching to improve the reliability and efficiency of the power supply system. Utility Model Content

[0005] In view of this, it is necessary to provide an adaptive output power switching circuit structure to solve the technical problems of low efficiency, severe heat generation and uneven switching caused by the use of isolation diodes in the existing dual power supply parallel scheme.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0007] This utility model provides an adaptive output power switching circuit structure, which is applied to a circuit with dual power supply. The first power supply circuit is connected to a first feedback control loop and a loop stabilization control circuit, and the second power supply circuit is connected to a second feedback control loop. The output terminals of the first power supply circuit and the second power supply circuit are connected in parallel to a common output terminal.

[0008] The first / second feedback control loop is used to sample the output state of the first / second power supply circuit and compare it with the first / second reference voltage to adjust the output power of the first / second power supply circuit to maintain the output voltage stability; wherein, the steady-state output voltage value set by the second feedback control loop is higher than the steady-state output voltage value set by the first feedback control loop.

[0009] The loop stabilization control circuit includes diode D11. The anode of diode D11 is connected to the feedback point F at the output of the first power supply circuit, and the cathode is connected to one end of capacitor C14. The other end of capacitor C14 is grounded. Resistor R30 is connected in parallel with capacitor C14. The cathode of diode D11 is also connected to the cathode of diode D12. The anode of diode D12 is connected to the base of PNP transistor Q3 through resistors R33 and R32 connected in series. The collector of PNP transistor Q3 is grounded and connected to one end of resistor R31. The other end of resistor R31 is connected to the common terminal of resistors R33 and R32. The emitter of transistor Q3 is connected to the reference voltage setting node of the first feedback control loop through resistor R29, and is connected to the output of the first power supply circuit through resistors R29 and R6 connected in series. Capacitor C15 is connected in parallel with resistor R31.

[0010] Preferably, the first feedback control loop includes a first PWM controller U1, a first optocoupler U2, a first reference voltage regulator U3, and a first voltage divider sampling module;

[0011] The reference input terminal of the first reference voltage regulator U3 and the input terminal of the first optocoupler U2 are connected to the sampling point of the first voltage divider sampling module, and are used to control the current of the input terminal of the first optocoupler U2 according to the sampling voltage.

[0012] The output terminal of the first optocoupler U2 is connected to the feedback pin of the first PWM controller U1 to form a first closed-loop feedback circuit, so as to adaptively adjust the output voltage of the first power supply circuit.

[0013] The first voltage divider sampling module is connected between the common output terminal and ground, and is used to sample the output voltage.

[0014] Preferably, the first power supply circuit includes a first transformer T1, and the first closed-loop feedback circuit includes an N-channel MOSFET Q1.

[0015] The gate of the MOS transistor Q1 is connected to the output terminal of the first PWM controller U1, the drain is connected to the input terminal of the first power supply circuit, and the source is grounded through resistor R13; the main current path of the MOS transistor Q1 is connected in series in the primary winding circuit of the first transformer T1.

[0016] Preferably, the second feedback control loop includes a second PWM controller U4, a second optocoupler U5, a second reference voltage regulator U6, and a second voltage divider sampling module;

[0017] The reference input terminal of the second reference voltage regulator U6 and the input terminal of the second optocoupler U5 are connected to the sampling point of the second voltage divider sampling module, and are used to control the current of the input terminal of the second optocoupler U5 according to the sampling voltage;

[0018] The output terminal of the second optocoupler U5 is connected to the feedback pin of the second PWM controller U4 to form a second closed-loop feedback circuit, so as to adaptively adjust the output voltage of the second power supply circuit.

[0019] The second voltage divider sampling module is connected between the common output terminal and ground, and is used to sample the output voltage.

[0020] Preferably, the second power supply circuit includes a second transformer T2, and the second closed-loop feedback circuit includes an N-channel MOSFET Q2;

[0021] The gate of the MOS transistor Q2 is connected to the output terminal of the first PWM controller U4, the drain is connected to the input terminal of the second power supply circuit, and the source is grounded through resistor R27; the main current path of the MOS transistor Q2 is connected in series in the primary winding circuit of the second transformer T2.

[0022] Preferably, the steady-state output voltage set by the second feedback control loop is 0.5V to 1V higher than the steady-state output voltage set by the first feedback control loop.

[0023] Preferably, the first power supply circuit is a DC power input and the second power supply circuit is an AC power input.

[0024] The beneficial effects of this utility model are:

[0025] 1. By removing the isolation diode connected in series in the output circuit in traditional solutions, the high power loss caused by the diode's forward voltage drop is fundamentally eliminated. The load can be directly supplied without overcoming the diode's voltage drop, significantly improving the overall efficiency. Simultaneously, with the main heat source eliminated, the circuit temperature rise is significantly reduced, improving long-term product reliability and lowering the requirements for heat dissipation design, thus contributing to miniaturization and cost reduction.

[0026] 2. By continuously monitoring the voltage state at feedback point F, the system determines whether it is powered by the second power supply or requires its own power. By controlling the on / off state of the switching devices, the reference voltage of the first power supply feedback loop is dynamically adjusted, enabling it to actively and stably enter standby mode when needed, thus avoiding loop conflicts when the two power supplies are connected in parallel. Ultimately, this achieves fast, smooth, and seamless switching between the two power supplies, ensuring no voltage fluctuations at the load end.

[0027] In summary, this utility model significantly improves work efficiency and completely solves the overheating problem, effectively controls material costs and supply chain risks, and optimizes both cost and efficiency. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a circuit structure in the prior art that ensures output stability by connecting diodes in series at the output terminals of the dual power supplies.

[0029] Figure 2 This is a schematic diagram of an embodiment of an adaptive output power switching circuit provided by this utility model. Detailed Implementation

[0030] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0031] In the description of this application, "multiple" means two or more, unless otherwise expressly and specifically defined.

[0032] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] Before introducing the embodiments of this utility model, the main problems solved by this utility model and the defects of the prior art will be explained.

[0034] When using a dual-power redundant backup design to ensure uninterrupted system operation, two power supplies are typically used simultaneously, with their common output connected to the same load. However, it's difficult for the two power supplies to be completely identical. When the voltage of one power supply is higher than the other, it affects the feedback loop of that power supply, causing output instability.

[0035] In response to this issue, such as Figure 1As shown, Figure 1 There is one set of DC power supply and one set of AC power supply, connected to the load terminal through a common input terminal (OUT+ and GND). Current methods typically use an AC power module ( Figure 1 A diode D8 is connected in series at the output terminal of the AC power input terminals L and N on the lower left side, and a diode D8 is connected in series at the output terminal of the DC power module ( Figure 1 A diode D3 is also connected in series at the output terminals of BAT+ and BAT- on the upper left. The output terminals of the two power supplies are connected in parallel through the diodes and then connected to the load. Utilizing the unidirectional conductivity of the diodes, current is prevented from flowing back from one power supply to the other, thus avoiding interference with their respective control loops and ensuring the stability of the output when each power supply operates independently. Furthermore, the design intentionally increases the output voltage of the AC power supply by 0.5V to 1V. When both power supplies operate simultaneously, because the AC output voltage is higher than the DC output voltage, the voltage at the common junction of the two diodes (i.e., the OUT+ terminal) is raised to the AC output voltage value.

[0036] Although this design is simple, under high current load conditions, the power loss (P = V) on diodes D3 and D8 is significant. f The voltage drop (×I) is very significant, causing severe overheating of the diode and affecting the overall efficiency of the device. Furthermore, when the AC power is suddenly disconnected, the voltage at the OUT+ terminal drops momentarily until the DC-side diode D3 changes from the cutoff state to forward bias and conducts, allowing the DC side to take over power. This switching process has a slight delay, which, for precision loads, leads to increased output voltage ripple and decreased stability.

[0037] To address the aforementioned problems, a specific embodiment of this utility model discloses an adaptive output power switching circuit structure, applied in a dual-power supply circuit. The first power supply circuit is connected to a first feedback control loop and a loop stabilization control circuit, and the second power supply circuit is connected to a second feedback control loop. The output terminals of the first power supply circuit and the second power supply circuit are connected in parallel to a common output terminal.

[0038] The first / second feedback control loop is used to sample the output state of the first / second power supply circuit and compare it with the first / second reference voltage to adjust the output power of the first / second power supply circuit to maintain the output voltage stability; wherein, the steady-state output voltage value set by the second feedback control loop is higher than the steady-state output voltage value set by the first feedback control loop.

[0039] The loop stabilization control circuit includes diode D11. The anode of diode D11 is connected to the feedback point F at the output of the first power supply circuit, and the cathode is connected to one end of capacitor C14. The other end of capacitor C14 is grounded. Resistor R30 is connected in parallel with capacitor C14. The cathode of diode D11 is also connected to the cathode of diode D12. The anode of diode D12 is connected to the base of PNP transistor Q3 through resistors R33 and R32 connected in series. The collector of PNP transistor Q3 is grounded and connected to one end of resistor R31. The other end of resistor R31 is connected to the common terminal of resistors R33 and R32. The emitter of transistor Q3 is connected to the reference voltage setting node of the first feedback control loop through resistor R29, and is connected to the output of the first power supply circuit through resistors R29 and R6 connected in series. Capacitor C15 is connected in parallel with resistor R31.

[0040] The circuit in this embodiment fundamentally eliminates the high power loss caused by the diode's forward voltage drop by removing the isolation diode connected in series in the output circuit in traditional solutions. Current can now be directly supplied to the load without overcoming the diode's voltage drop, significantly improving overall system efficiency. By adding a loop stabilizing source on the first power supply side, the voltage state of the feedback point F inside the first power supply can be continuously monitored, intelligently determining whether the system is powered by the second power supply or needs to be powered independently. By controlling the on / off state of Q3, the reference voltage of the first power supply feedback loop is dynamically adjusted, allowing it to actively and stably enter standby mode when needed. This avoids loop conflicts when dual power supplies are connected in parallel, achieving fast, smooth, and seamless switching between the two power supplies, ensuring no voltage fluctuations at the load end.

[0041] The following is combined Figure 2 The above circuit structure will be described in detail.

[0042] like Figure 2 As shown, assuming the first power supply is a DC power supply (BAT+ and BAT-), the second power supply is an AC power supply (L and N), and the feedback voltage of the DC side control loop is set to be about 0.5V~1V lower than that of the AC side, then the circuit has 4 input states:

[0043] ① DC power supply: When using DC power supply, the output is driven by the DC side;

[0044] ② AC power supply: When using AC power supply, the output is driven by the AC side;

[0045] ③ DC to AC switching: When the load is powered by DC, the output will automatically switch to AC when the AC side is powered on.

[0046] ④ AC to DC switching: When AC power is applied, the DC side is in standby mode. When the AC power is disconnected, the output will automatically switch to DC side for load application.

[0047] In states ① and ②, the power supply is either AC or DC, and both power supplies operate as conventional power sources.

[0048] However, when in state ③, the DC side is powered by the first transformer T1 and diode D2 to supply the load to OUT+. If AC is connected at this time, the AC side is powered by the second transformer T2 and diode D7 to supply the load to OUT+. Since the AC output voltage is higher than the DC output voltage, the load switches to AC supply. Only by disconnecting the AC input can the load switch back to DC supply. At this time, the DC output voltage also becomes too high, following the AC output voltage, causing the loop reference to rise. To solve this DC loop stability problem, we added a loop stability control circuit, the principle of which is as follows:

[0049] Since the AC output voltage is higher than the DC output voltage, for example, if the AC output voltage is set to around 24.5V, the reference voltage of the first reference regulator U3 also increases, resulting in a decrease in its on-resistance. Consequently, the current at pins 1 and 2 of the first optocoupler U2 increases, while the internal resistance at pins 3 and 4 decreases. The voltage at pin 1 of the first PWM controller U1 decreases, the duty cycle at pin 6 decreases, the output voltage of the auxiliary winding N3 of the first transformer T1 decreases, and the voltage at the feedback point F at the output of the first power supply circuit decreases. This causes the voltage at the positive terminal of capacitor C14 to decrease, the current at diode D12 to decrease, and the voltage at the terminal of capacitor C15 to decrease. The PNP transistor Q3 then conducts, its internal resistance decreases, and the voltage across resistor R14, which is connected in parallel with the emitter and collector of transistor Q3, decreases. This causes the reference voltage of the first reference regulator U3 to decrease, thus stabilizing the reference voltage and completing closed-loop control.

[0050] In state ④, when the AC side is disconnected, the second transformer T2 stops working and stops outputting voltage. The output voltage is then supplied by the first transformer T1, increasing the output duty cycle. The voltage at the feedback point F at the output terminal rises, and the voltage at the positive terminal of capacitor C14 also rises. Consequently, the current of diode D12 increases, and the voltage at the terminal of capacitor C15 rises. When the voltage rises to more than approximately 1.5V, transistor Q3 is cut off and disconnected from its parallel connection with R14. The output voltage drops, and the stable DC side output voltage is approximately 23.5V, which is 0.5V to 1V lower than the DC side output voltage, thus completing the AC to DC switching process.

[0051] Therefore, the above process achieves seamless AC / DC switching: when the DC side is powered on during normal DC power supply, the output switches to AC power supply, and the DC side is idle and waiting; when the DC side is waiting, the AC side is disconnected, and the output switches to DC power supply.

[0052] The circuit provided in this embodiment uses common electronic components for precise sampling and level conversion to transform the power supply's operating state into a linear adjustment of the reference voltage. The adjustment methods are all based on solutions using general-purpose components, eliminating the need for expensive dedicated control ICs. This effectively controls material costs and supply chain risks, resulting in a deeply optimized design in terms of both cost and efficiency, and giving it strong engineering practicality.

[0053] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. An adaptive output power switching circuit structure, applied in a circuit with dual power supply, characterized in that, The first power supply circuit is connected to a first feedback control loop and a loop stabilization control circuit, and the second power supply circuit is connected to a second feedback control loop; the output terminals of the first power supply circuit and the second power supply circuit are connected in parallel to a common output terminal. The first / second feedback control loop is used to sample the output state of the first / second power supply circuit and compare it with the first / second reference voltage to adjust the output power of the first / second power supply circuit to maintain the output voltage stability; wherein, the steady-state output voltage value set by the second feedback control loop is higher than the steady-state output voltage value set by the first feedback control loop. The loop stabilization control circuit includes diode D11. The anode of diode D11 is connected to the feedback point F at the output of the first power supply circuit, and the cathode is connected to one end of capacitor C14. The other end of capacitor C14 is grounded. Resistor R30 is connected in parallel with capacitor C14. The cathode of diode D11 is also connected to the cathode of diode D12. The anode of diode D12 is connected to the base of PNP transistor Q3 through resistors R33 and R32 connected in series. The collector of PNP transistor Q3 is grounded and connected to one end of resistor R31. The other end of resistor R31 is connected to the common terminal of resistors R33 and R32. The emitter of transistor Q3 is connected to the reference voltage setting node of the first feedback control loop through resistor R29, and is connected to the output of the first power supply circuit through resistors R29 and R6 connected in series. Capacitor C15 is connected in parallel with resistor R31.

2. The adaptive output power switching circuit structure according to claim 1, characterized in that, The first feedback control loop includes a first PWM controller U1, a first optocoupler U2, a first reference voltage regulator U3, and a first voltage divider sampling module; The reference input terminal of the first reference voltage regulator U3 and the input terminal of the first optocoupler U2 are connected to the sampling point of the first voltage divider sampling module, and are used to control the current of the input terminal of the first optocoupler U2 according to the sampling voltage. The output terminal of the first optocoupler U2 is connected to the feedback pin of the first PWM controller U1 to form a first closed-loop feedback circuit, so as to adaptively adjust the output voltage of the first power supply circuit. The first voltage divider sampling module is connected between the common output terminal and ground, and is used to sample the output voltage.

3. The adaptive output power switching circuit structure according to claim 2, characterized in that, The first power supply circuit includes a first transformer T1, and the first closed-loop feedback circuit includes an N-channel MOSFET Q1. The gate of the MOS transistor Q1 is connected to the output terminal of the first PWM controller U1, the drain is connected to the input terminal of the first power supply circuit, and the source is grounded through resistor R13; the main current path of the MOS transistor Q1 is connected in series in the primary winding circuit of the first transformer T1.

4. The adaptive output power switching circuit structure according to claim 1, characterized in that, The second feedback control loop includes a second PWM controller U4, a second optocoupler U5, a second reference voltage regulator U6, and a second voltage divider sampling module; The reference input terminal of the second reference voltage regulator U6 and the input terminal of the second optocoupler U5 are connected to the sampling point of the second voltage divider sampling module, and are used to control the current of the input terminal of the second optocoupler U5 according to the sampling voltage; The output terminal of the second optocoupler U5 is connected to the feedback pin of the second PWM controller U4 to form a second closed-loop feedback circuit, so as to adaptively adjust the output voltage of the second power supply circuit. The second voltage divider sampling module is connected between the common output terminal and ground, and is used to sample the output voltage.

5. The adaptive output power switching circuit structure according to claim 4, characterized in that, The second power supply circuit includes a second transformer T2, and the second closed-loop feedback circuit includes an N-channel MOSFET Q2. The gate of the MOS transistor Q2 is connected to the output terminal of the first PWM controller U4, the drain is connected to the input terminal of the second power supply circuit, and the source is grounded through resistor R27; the main current path of the MOS transistor Q2 is connected in series in the primary winding circuit of the second transformer T2.

6. The adaptive output power switching circuit structure according to claim 1, characterized in that, The steady-state output voltage set by the second feedback control loop is 0.5V to 1V higher than the steady-state output voltage set by the first feedback control loop.

7. The adaptive output power switching circuit structure according to claim 1, characterized in that, The first power supply circuit is a DC power input, and the second power supply circuit is an AC power input.

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