Capacitance monitoring and adjusting circuit of switching power supply
By monitoring the capacitance of the electrolytic capacitor in real time and adjusting the duty cycle of the switching transistor in the switching power supply, the problem of high failure rate of electrolytic capacitors is solved, the safety and reliability of the switching power supply are improved, and performance degradation caused by capacitor aging is avoided.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- DONGGUAN AOHAI TECH CO LTD
- Filing Date
- 2025-05-23
- Publication Date
- 2026-04-28
AI Technical Summary
Electrolytic capacitors in switching power supplies have a high failure rate. Existing technology cannot track the aging process of capacitors in real time, leading to performance degradation. In addition, increasing the design margin of capacitors will increase cost and size.
The controller compares the capacitance of the electrolytic capacitor with a set threshold, adjusts the duty cycle of the switching transistor, reduces the output power of the switching power supply, monitors the status of the electrolytic capacitor in real time, reduces the operating ripple current, and prevents capacitor failure.
This technology enables real-time monitoring of electrolytic capacitor status without increasing circuit complexity, thereby improving the safety and reliability of switching power supplies and reducing the risk of capacitor failure.
Smart Images
Figure CN224178087U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of switching power supply technology, and in particular to a capacitor monitoring and regulation circuit for a switching power supply. Background Technology
[0002] In switching power supplies, electrolytic capacitor failure accounts for as much as 40%-60%, making it the leading cause of power supply malfunctions. During operation, the electrolyte in the capacitors gradually diminishes due to internal chemical reactions. Prolonged high-temperature operation also causes electrolyte evaporation, leading to a decrease in capacitance. This reduction in capacitance exacerbates capacitor heating, ultimately resulting in capacitor failure. Currently, the industry commonly uses methods to increase capacitor design margins. However, selecting capacitors with higher rated voltages or larger capacities increases material costs and power supply size, and makes it impossible to track capacitor aging in real time, failing to fundamentally solve the performance degradation problem caused by capacitance decay.
[0003] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content
[0004] In view of at least one of the above technical problems, this application provides a capacitor monitoring and regulation circuit for a switching power supply.
[0005] This application provides a capacitor monitoring and regulation circuit for a switching power supply, the circuit comprising:
[0006] The input circuit includes an electrolytic capacitor.
[0007] Power conversion circuit, which is connected to the input circuit;
[0008] The control circuit includes a controller, a switching transistor, and a first resistor. The first terminal of the controller is connected to an electrolytic capacitor, the gate of the switching transistor is connected to the second terminal of the controller, the drain of the switching transistor is connected to the power conversion circuit, the first terminal of the first resistor is connected to the third terminal of the controller and the source of the switching transistor, and the second terminal of the first resistor is grounded.
[0009] The controller compares the capacitance of the electrolytic capacitor with a set threshold. When the capacitance of the electrolytic capacitor is less than the set threshold, the controller adjusts the duty cycle of the switching transistor to reduce the output power of the switching power supply, thereby reducing the operating ripple current of the electrolytic capacitor.
[0010] This capacitor monitoring and adjustment circuit compares the capacitance of the electrolytic capacitor with a set threshold through a controller. When the capacitance of the electrolytic capacitor is less than the set threshold, the controller adjusts the duty cycle of the switching transistor to reduce the output power of the switching power supply, thereby reducing the operating ripple current of the electrolytic capacitor. This allows for real-time monitoring of the capacitance of the electrolytic capacitor and real-time tracking of its status without increasing circuit complexity, thus improving the safety of the switching power supply.
[0011] In some possible implementations, the second terminal of the controller is used to output a PWM drive signal to the gate of the switching transistor.
[0012] In some possible implementations, the power conversion circuit includes a transformer; the first resistor is used to acquire the transformer's excitation peak current.
[0013] In some possible implementations, the capacitance calculation formula for an electrolytic capacitor is as follows:
[0014]
[0015] Where C is the capacitance of the electrolytic capacitor, Lp is the inductance of the transformer, Ipk is the peak excitation current of the transformer, F is the switching frequency of the switching power supply, Vmax is the maximum voltage of the electrolytic capacitor, Vmin is the minimum voltage of the electrolytic capacitor, and T2 is the time for the electrolytic capacitor to release energy.
[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a circuit diagram of the capacitor monitoring and adjustment circuit of the switching power supply provided in the embodiments of this application; Detailed Implementation
[0019] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.
[0020] like Figure 1 As shown, one embodiment provides a capacitor monitoring and regulation circuit for a switching power supply, the circuit including: an input circuit 100, a power conversion circuit 200 and a control circuit 300.
[0021] The input circuit 100 includes an electrolytic capacitor; the power conversion circuit 200 is connected to the input circuit 100; the control circuit 300 includes a controller U1, a switching transistor Q1, and a first resistor R1. The first terminal of the controller U1 is connected to the electrolytic capacitor, the gate of the switching transistor Q1 is connected to the second terminal of the controller U1, the drain of the switching transistor Q1 is connected to the power conversion circuit 200, the first terminal of the first resistor R1 is connected to the third terminal of the controller U1 and the source of the switching transistor Q1, and the second terminal of the first resistor R1 is grounded. The controller U1 is used to compare the capacitance of the electrolytic capacitor with a set threshold. When the capacitance of the electrolytic capacitor is less than the set threshold, the controller U1 adjusts the duty cycle of the switching transistor Q1 to reduce the output power of the switching power supply, thereby reducing the operating ripple current of the electrolytic capacitor.
[0022] This capacitor monitoring and adjustment circuit compares the capacitance of the electrolytic capacitor with a set threshold through controller U1. When the capacitance of the electrolytic capacitor is less than the set threshold, controller U1 adjusts the duty cycle of switching transistor Q1 to reduce the output power of the switching power supply, thereby reducing the operating ripple current of the electrolytic capacitor. Without increasing the circuit complexity, it can monitor the capacitance of the electrolytic capacitor in real time and track the status of the electrolytic capacitor in real time, thereby improving the safety of the switching power supply.
[0023] like Figure 1 As shown, in some embodiments, the second terminal of the controller U1 is used to output a PWM drive signal to the gate of the switching transistor Q1.
[0024] like Figure 1 As shown, in some embodiments, the power conversion circuit 200 includes a transformer; the first resistor R1 is used to collect the peak excitation current of the transformer.
[0025] like Figure 1 As shown, in some embodiments, according to the law of conservation of energy, the stored energy of an electrolytic capacitor is equal to the released energy of the electrolytic capacitor.
[0026] The formula for calculating the stored energy of an electrolytic capacitor is:
[0027]
[0028] The formula for calculating the energy released by an electrolytic capacitor is:
[0029]
[0030] After modification, the formula for calculating the capacitance of an electrolytic capacitor is:
[0031]
[0032] Where C is the capacitance of the electrolytic capacitor, Lp is the inductance of the transformer, Ipk is the peak excitation current of the transformer, F is the switching frequency of the switching power supply, Vmax is the maximum voltage of the electrolytic capacitor, Vmin is the minimum voltage of the electrolytic capacitor, and T2 is the time for the electrolytic capacitor to release energy.
[0033] It is worth noting that the inductance of the transformer and the switching frequency of the switching power supply are known quantities. The maximum voltage, minimum voltage, and energy release time of the electrolytic capacitor can be obtained by detecting the first terminal of the controller U1. The peak excitation current of the transformer can be obtained by detecting the first resistor R1 by detecting the third terminal of the controller U1.
[0034] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0035] In the embodiments of this application, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.
[0036] The above are merely preferred embodiments of this application and do not constitute any limitation on this application. Any person skilled in the art can make many possible variations and modifications to the technical solution of this application, or modify it into equivalent embodiments, without departing from the scope of the technical solution of this application. Therefore, all equivalent changes made based on the shape, structure, and principle of this application without departing from the content of the technical solution of this application should be covered within the protection scope of this application.
Claims
1. A capacitor monitoring and regulation circuit for a switching power supply, characterized in that, The circuit includes: Input circuit, the input circuit including an electrolytic capacitor; A power conversion circuit, wherein the power conversion circuit is connected to the input circuit; The control circuit includes a controller, a switching transistor, and a first resistor. The first terminal of the controller is connected to the electrolytic capacitor, the gate of the switching transistor is connected to the second terminal of the controller, the drain of the switching transistor is connected to the power conversion circuit, the first terminal of the first resistor is connected to the third terminal of the controller and the source of the switching transistor, and the second terminal of the first resistor is grounded. The controller is used to compare the capacitance of the electrolytic capacitor with a set threshold. When the capacitance of the electrolytic capacitor is less than the set threshold, the controller adjusts the duty cycle of the switching transistor to reduce the output power of the switching power supply, thereby reducing the operating ripple current of the electrolytic capacitor.
2. The capacitor monitoring and adjustment circuit of the switching power supply according to claim 1, characterized in that, The second terminal of the controller is used to output a PWM drive signal to the gate of the switching transistor.
3. The capacitor monitoring and adjustment circuit for a switching power supply according to claim 1, characterized in that, The power conversion circuit includes a transformer; The first resistor is used to collect the peak excitation current of the transformer.
4. The capacitor monitoring and adjustment circuit of the switching power supply according to claim 3, characterized in that, The formula for calculating the capacitance of the electrolytic capacitor is as follows: Where C is the capacitance of the electrolytic capacitor, Lp is the inductance of the transformer, Ipk is the peak excitation current of the transformer, F is the switching frequency of the switching power supply, Vmax is the maximum voltage of the electrolytic capacitor, Vmin is the minimum voltage of the electrolytic capacitor, and T2 is the time for the electrolytic capacitor to release energy.