Loop competition control circuit and switching power supply
By using a loop competition control circuit, the current loop reference voltage is adjusted using a TL431 and a voltage divider circuit. Combined with an operational amplifier and an optocoupler, closed-loop control of the current loop of the switching power supply is achieved, which solves the voltage and current loop competition problem at the moment of startup of the switching power supply and improves the stability and adaptability of the power supply.
Patent Information
- Application Number
- CN202423285601.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-12-09
- Estimated Expiration
- 2034-12-30
AI Technical Summary
In existing technologies, switching power supplies are prone to voltage and current loop competition at startup, resulting in abnormal output voltage waveforms. Traditional methods of adjusting current loop parameters cannot effectively avoid this phenomenon, especially under complex load environments, affecting the response speed and stability of the current loop, and limiting its application to low-power products.
A loop competition control circuit is adopted, which controls the current loop reference voltage through TL431, sampling circuit and voltage divider circuit. Combined with operational amplifier and optocoupler, the closed-loop control of the current loop is realized. The current loop reference signal is flexibly adjusted to avoid voltage and current loop competition and improve the overcurrent capability at the moment of power-on.
It effectively avoids voltage and current loop competition, making the switching power supply output stable and monotonically increase, improving the overcurrent capability at the moment of power-on, adapting to various complex application scenarios, and ensuring the stability and response speed of the current loop.
Smart Images
Figure CN223652153U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of switching converters, and in particular to a loop competition control circuit and a switching power supply. Background Technology
[0002] As power supply products are increasingly used in a wider range of applications and more complex environments, especially in applications with large capacitive and inductive loads, a large current spike is generated at the output terminal during startup due to the characteristics of the output load. This causes the current loop to be triggered before the output is fully established, resulting in voltage and current loop competition. This leads to abnormal output voltage waveforms or malfunctions, and these abnormalities worsen with increasing load. Therefore, it is essential to introduce a voltage and current loop competition control strategy during product startup to avoid voltage and current loop competition caused by startup inrush current, enabling the product to adapt to various load scenarios.
[0003] If we directly use the traditional method of adjusting the current loop parameters to slow down the current loop and suppress the voltage-current loop competition phenomenon at the moment of product startup, the following drawbacks exist:
[0004] (1) If voltage and current loop competition is avoided by adjusting the current loop parameters, it is achieved by slowing down the current loop, which cannot truly avoid voltage and current loop competition. When the working environment is more severe or the product power is greater, voltage and current loop competition will still occur.
[0005] (2) In order to solve the problem of current loop operation caused by current spikes during startup, the current loop is slowed down. Therefore, this control strategy will also greatly affect the response speed and stability of the current loop.
[0006] (3) Since the traditional current loop is a fixed reference, this method can only be applied to low-power products and simple application scenarios. Utility Model Content
[0007] In view of this, the technical problem to be solved by this utility model is to provide a loop competition control circuit and a switching power supply, which at least partially solves one of the technical problems existing in the prior art.
[0008] As a first aspect of this utility model, the embodiment of the loop competition control circuit is as follows:
[0009] A loop contention control circuit is applied to a switching power supply, the switching power supply including a voltage loop and a current loop, the current loop including a reference signal input terminal for inputting a current loop reference voltage, wherein the loop contention control circuit includes:
[0010] The TL431 has an anode for connecting to signal ground, a cathode for inputting the power supply voltage, and a control electrode for outputting the current loop reference voltage.
[0011] A sampling circuit, connected to the switching power supply, is used to obtain a first sampling signal characterizing the magnitude of the output voltage of the switching power supply.
[0012] The first voltage divider circuit has one end connected to the cathode of the TL431 and the other end connected to the control electrode of the TL431.
[0013] The second voltage divider circuit has one end connected to the control terminal of the TL431, the other end connected to signal ground, and the control terminal used to input the first sampling signal.
[0014] When the switching power supply is working, the second voltage divider circuit controls the voltage obtained by the second voltage divider circuit according to the magnitude of the first sampled signal, thereby controlling the magnitude of the current loop reference voltage.
[0015] Preferably, the sampling circuit includes a first voltage divider and a second voltage divider. One end of the first voltage divider is connected to the output terminal of the switching power supply. The other end of the first voltage divider and one end of the second voltage divider are connected together to output the first sampling signal. The other end of the second voltage divider is connected to signal ground.
[0016] Preferably, the first voltage divider and the second voltage divider are resistors.
[0017] Preferably, the first voltage divider circuit includes a resistor.
[0018] Preferably, the second voltage divider circuit includes resistors R2, R4, and R5, and a switching transistor Q1. One end of resistor R2 is connected to the control terminal of the TL431, and the other end of resistor R2 is connected to both one end of resistor R4 and one end of resistor R5. The other end of resistor R4 is connected to one end of the switching transistor Q1, and the other end of resistor R5 and the other end of the switching transistor Q1 are connected together to the signal ground. The control terminal of the switching transistor Q1 is the control terminal of the second voltage divider circuit, used to input the first sampling signal.
[0019] Preferably, the switching transistor Q1 is a MOSFET.
[0020] Preferably, the sampling circuit includes resistors R6 and R8. One end of resistor R6 is connected to the output terminal of the switching power supply, and the other end of resistor R6 is connected to one end of resistor R8 to output the first sampling signal. The other end of resistor R8 is connected to signal ground. The first voltage divider circuit includes resistor R1. The second voltage divider circuit includes resistors R2, R4, R5, and MOSFET Q1. One end of resistor R2 is connected to the control terminal of the TL431. The other end of resistor R2 is connected to one end of resistor R4 and one end of resistor R5. The other end of resistor R4 is connected to one end of MOSFET Q1. The other end of resistor R5 and the other end of MOSFET Q1 are connected together to signal ground. The control terminal of MOSFET Q1 is the control terminal of the second voltage divider circuit, used to input the first sampling signal.
[0021] As a second aspect of this utility model, the technical solution of the provided switching power supply embodiment is as follows:
[0022] A switching power supply includes a voltage loop and a current loop, the current loop including a reference signal input terminal for inputting a current loop reference voltage, wherein the switching power supply further includes the loop contention control circuit described in any of the first aspects above.
[0023] Preferably, the current loop includes an operational amplifier U2, the non-inverting input of the operational amplifier U2 is the reference signal input of the current loop, the inverting input of the operational amplifier U2 is input with a second sampling signal representing the magnitude of the output current of the switching power supply, and the signal output from the output of the operational amplifier U2 is used to realize the closed-loop control of the current loop.
[0024] Furthermore, the current loop also includes an optocoupler OP1. The anode of the emitter of the optocoupler OP1 is used to input the power supply voltage, the cathode of the emitter of the optocoupler OP1 is connected to the output terminal of the operational amplifier U2, the signal output from the collector of the receiver of the optocoupler OP1 is used to realize the closed-loop control of the current loop, and the emitter of the receiver of the optocoupler OP1 is used to connect to the primary ground of the switching power supply.
[0025] The advantages of this utility model compared to the prior art are as follows:
[0026] In this embodiment of the utility model, when the switching power supply is working, the second voltage divider circuit controls the voltage obtained by the second voltage divider circuit according to the magnitude of the first sampling signal, thereby controlling the magnitude of the current loop reference voltage. This not only effectively avoids the phenomenon of voltage and current loop competition, thus enabling the output of the switching power supply to rise monotonically, but also improves the overcurrent capability of the switching power supply at the moment of power-on, enabling the product to adapt to various complex application scenarios. Attached Figure Description
[0027] Figure 1 This is an application schematic diagram of a specific circuit diagram of the loop competition control circuit of the first embodiment of this utility model. Detailed Implementation
[0028] To make the above-mentioned objectives, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.
[0029] It should be noted that the terms "comprising" and "having" and any variations thereof described in the specification and claims of this application are intended to cover non-exclusive inclusion. For example, including a series of components, unit circuits or control timings is not necessarily limited to those components, unit circuits or control timings that are explicitly listed, but may include components, unit circuits or control timings that are not explicitly listed or that are inherent to these circuits.
[0030] Furthermore, unless otherwise specified, the embodiments and features described in this application may be combined with each other.
[0031] It should be understood that, in the specification and claims, when an element is described as being "connected" to another element, that element may be "directly connected" to that other element or "connected" to that other element through a third element; when a step is described as being connected to another step, that step may be connected directly to that other step or connected to that other step through a third step.
[0032] First Embodiment
[0033] This embodiment provides a loop contention control circuit applied to a switching power supply. The switching power supply includes a voltage loop and a current loop. The current loop includes a reference signal input terminal for inputting a reference voltage for the current loop. The loop contention control circuit includes:
[0034] The TL431 has an anode for connecting to signal ground, a cathode for input power supply voltage, and a control electrode for output current loop reference voltage.
[0035] The sampling circuit is connected to the switching power supply and is used to obtain a first sampling signal that characterizes the magnitude of the output voltage of the switching power supply.
[0036] The first voltage divider circuit has one end connected to the cathode of TL431 and the other end connected to the control electrode of TL431.
[0037] The second voltage divider circuit has one end connected to the control terminal of the TL431, the other end connected to signal ground, and the control terminal used to input the first sampling signal.
[0038] When the switching power supply is working, the second voltage divider circuit controls the voltage obtained by the second voltage divider circuit according to the magnitude of the first sampling signal, thereby controlling the magnitude of the current loop reference voltage.
[0039] In this embodiment, when the switching power supply is working, the second voltage divider circuit controls the voltage obtained by the second voltage divider circuit according to the magnitude of the first sampling signal, thereby controlling the magnitude of the current loop reference voltage. This not only effectively avoids the phenomenon of voltage and current loop competition, thus enabling the output of the switching power supply to rise monotonically, but also improves the overcurrent capability of the switching power supply at the moment of power-on, enabling the product to adapt to various complex application scenarios.
[0040] Figure 1 For a specific circuit diagram of the loop competition control circuit of the first embodiment of this utility model, please refer to the application principle diagram. Figure 1 :
[0041] The sampling circuit includes a first voltage divider and a second voltage divider. One end of the first voltage divider is connected to the output terminal of the switching power supply. The other end of the first voltage divider and one end of the second voltage divider are connected together to output the first sampling signal. The other end of the second voltage divider is connected to the signal ground.
[0042] Specifically, the first voltage divider is resistor R6 and the second voltage divider is resistor R7.
[0043] The first voltage divider circuit includes a resistor R1.
[0044] The second voltage divider circuit includes resistors R2, R4, and R5, and a switching transistor Q1. One end of resistor R2 is connected to the control terminal of TL431, and the other end of resistor R2 is connected to one end of resistor R4 and one end of resistor R5. The other end of resistor R4 is connected to one end of switching transistor Q1, and the other end of resistor R5 and the other end of switching transistor Q1 are connected together to the signal ground. The control terminal of switching transistor Q1 is the control terminal of the second voltage divider circuit, which is used to input the first sampling signal.
[0045] Second Embodiment
[0046] This embodiment provides a switching power supply, which includes a voltage loop and a current loop. The current loop includes a reference signal input terminal for inputting a reference voltage. The switching power supply also includes any one of the loop contention control circuits from the first embodiment. Because this embodiment includes any one of the loop contention control circuits from the first embodiment, it can effectively avoid voltage and current loop contention.
[0047] Please continue reading Figure 1 The current loop includes operational amplifier U2. The non-inverting input of operational amplifier U2 serves as the reference signal input (Iref) for the current loop. The inverting input of operational amplifier U2 receives the second sampling signal (Isense), which characterizes the magnitude of the switching power supply's output current. The output signal of operational amplifier U2 is used to achieve closed-loop control of the current loop. Resistor R8, capacitor C1, and capacitor C2, connected between the inverting input and output of operational amplifier U2, form loop compensation.
[0048] Furthermore, the current loop also includes an optocoupler OP1. The anode of the OP1 transmitter is used to input the supply voltage, the cathode of the OP1 transmitter is connected to the output of the operational amplifier U2, and the signal output from the collector of the OP1 receiver is used to achieve closed-loop control of the current loop. The emitter of the OP1 receiver is connected to the primary ground of the switching power supply. Because we often place the control chip on the primary side of the switching power supply during circuit design, an optocoupler is needed for primary-secondary isolation to ensure power supply safety. The anode of the OP1 transmitter receives the supply voltage through resistor R10 to prevent excessive current through the LED from damaging the optocoupler OP1. The resistor R9 connecting the anode and cathode of the OP1 transmitter is for current shunting, providing quiescent operating current for the operational amplifier U2.
[0049] Figure 1 When the switching power supply is running normally, the second sampling signal Isense is compared with the current loop reference signal Iref. The loop modulation signal generated by the comparison controls the brightness adjustment controller signal FB of the primary side light-emitting diode of the optocoupler OP1, thereby realizing the closed-loop control of the current loop. Figure 1 The working principle of the circuit at the moment of power-on of the switching power supply is analyzed as follows:
[0050] When the output voltage Vout of the switching power supply is relatively low, the voltage is low due to the voltage division of resistor R7 through resistor R6 and resistor R7, which prevents MOSFET Q1 from conducting. At this time, the current loop reference signal Iref is relatively high.
[0051] After the output voltage Vout of the switching power supply reaches a certain level within a certain time, the voltage across resistor R7, through resistors R6 and R7, is divided to reach the turn-on voltage of MOSFET Q1. MOSFET Q1 then conducts. Resistors R4 and R5 are connected in parallel, resulting in a smaller current loop reference signal Iref. This current loop reference signal Iref represents the stable constant current point for the product. By flexibly adjusting the comparison between the current loop reference signal Iref and the second sampling signal Isense, not only can the voltage-current loop competition problem at power-on be avoided, but the overcurrent capability at power-on can also be improved. When the switching power supply is operating at a constant current output, the speed of the constant current loop effect can be adjusted using resistors R8, C1, and C2 to ensure output stability during constant current operation.
[0052] The above are merely preferred embodiments of the present utility model. It should be noted that the above preferred embodiments should not be regarded as limitations on the present utility model. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present utility model. These improvements and modifications should also be regarded as the protection scope of the present utility model. The protection scope of the present utility model shall be determined by the scope defined in the claims.
Claims
1. A loop competition control circuit, applied to a switching power supply, the switching power supply including a voltage loop and a current loop, the current loop including a reference signal input terminal for inputting a reference voltage for the current loop, characterized in that, The loop contention control circuit includes: The TL431 has an anode for connecting to signal ground, a cathode for inputting the power supply voltage, and a control electrode for outputting the current loop reference voltage. A sampling circuit, connected to the switching power supply, is used to obtain a first sampling signal characterizing the magnitude of the output voltage of the switching power supply. The first voltage divider circuit has one end connected to the cathode of the TL431 and the other end connected to the control electrode of the TL431. The second voltage divider circuit has one end connected to the control terminal of the TL431, the other end connected to signal ground, and the control terminal used to input the first sampling signal. When the switching power supply is working, the second voltage divider circuit controls the voltage obtained by the second voltage divider circuit according to the magnitude of the first sampled signal, thereby controlling the magnitude of the current loop reference voltage.
2. The loop contention control circuit according to claim 1, characterized in that: The sampling circuit includes a first voltage divider and a second voltage divider. One end of the first voltage divider is connected to the output terminal of the switching power supply. The other end of the first voltage divider and one end of the second voltage divider are connected together to output the first sampling signal. The other end of the second voltage divider is connected to signal ground.
3. The loop contention control circuit according to claim 2, characterized in that: The first voltage divider and the second voltage divider are resistors.
4. The loop contention control circuit according to claim 1, characterized in that: The first voltage divider circuit includes a resistor.
5. The loop contention control circuit according to claim 1, characterized in that: The second voltage divider circuit includes resistors R2, R4, and R5, and a switching transistor Q1. One end of resistor R2 is connected to the control terminal of the TL431, and the other end of resistor R2 is connected to both one end of resistor R4 and one end of resistor R5. The other end of resistor R4 is connected to one end of the switching transistor Q1, and the other end of resistor R5 and the other end of the switching transistor Q1 are connected together to the signal ground. The control terminal of the switching transistor Q1 is the control terminal of the second voltage divider circuit, used to input the first sampling signal.
6. The loop contention control circuit according to claim 5, characterized in that: The switching transistor Q1 is a MOSFET.
7. The loop contention control circuit according to claim 1, characterized in that: The sampling circuit includes resistor R6 and resistor R8. One end of resistor R6 is connected to the output terminal of the switching power supply. The other end of resistor R6 and one end of resistor R8 are connected together to output the first sampling signal. The other end of resistor R8 is connected to signal ground. The first voltage divider circuit includes a resistor R1; The second voltage divider circuit includes resistors R2, R4, and R5, and a MOSFET Q1. One end of resistor R2 is connected to the control terminal of the TL431, and the other end of resistor R2 is connected to both one end of resistor R4 and one end of resistor R5. The other end of resistor R4 is connected to one end of the MOSFET Q1, and the other end of resistor R5 and the other end of MOSFET Q1 are connected together to the signal ground. The control terminal of MOSFET Q1 is the control terminal of the second voltage divider circuit, used to input the first sampling signal.
8. A switching power supply, the switching power supply comprising a voltage loop and a current loop, the current loop including a reference signal input terminal for inputting a reference voltage for the current loop, characterized in that: The switching power supply further includes the loop contention control circuit described in any one of claims 1 to 7.
9. The switching power supply according to claim 8, characterized in that: The current loop includes an operational amplifier U2. The non-inverting input of the operational amplifier U2 is the reference signal input of the current loop. The inverting input of the operational amplifier U2 is input with a second sampling signal that represents the magnitude of the output current of the switching power supply. The signal output from the output of the operational amplifier U2 is used to realize the closed-loop control of the current loop.
10. The switching power supply according to claim 9, characterized in that: The current loop also includes an optocoupler OP1. The anode of the emitting end of the optocoupler OP1 is used to input the power supply voltage, the cathode of the emitting end of the optocoupler OP1 is connected to the output terminal of the operational amplifier U2, the signal output from the collector of the receiving end of the optocoupler OP1 is used to realize the closed-loop control of the current loop, and the emitter of the receiving end of the optocoupler OP1 is used to connect to the primary ground of the switching power supply.