scholarly journals ESR Estimation Schemes of Output Capacitor for Buck Converter from Capacitor Perspective

Electronics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1596
Author(s):  
Lei Ren ◽  
Lei Zhang ◽  
Chunying Gong
Keyword(s):  
Buck Converter ◽  
Electrolytic Capacitor ◽  
Equivalent Series Resistance ◽  
Power Electronic Converters ◽  
Aluminum Electrolytic Capacitor ◽  
Advantages And Disadvantages ◽  
Optimal Period ◽  
Current Characteristics ◽  
Output Capacitor ◽  
Conduction Mode

The aluminum electrolytic capacitor (AEC) is one of the most vulnerable parts in power electronic converters and its reliability is crucial to the whole system. With the growth of service time, the equivalent series resistance (ESR) increases and the capacitance (C) decreases due to the loss of electrolytes, which will result in extra power loss and even damage to transistors. To prevent significant damages, the AEC must be replaced at an optimal period and online health monitoring is indispensable. Through the analysis of degradation parameters (ESR and C), ESR is proved to be a better health indicator and therefore is determined as the monitoring parameter for AEC. From the capacitor perspective, ESR estimation schemes of output capacitors for a Buck converter are studied. Based on the voltage–current characteristics, two ESR calculation models are proposed, which are applicable for both continuous conduction mode (CCM) and discontinuous conduction mode (DCM). From the point of implementation view, the advantages and disadvantages of the two estimation schemes are pointed out, respectively. A Buck prototype is built and tested, and simulation and experimental results are provided to validate the proposed ESR estimation schemes.

Comparison of Aluminum Electrolytic Capacitor Lifetimes Using Accelerated Life Testing

2014 ◽  
Vol 2014 (1) ◽  
pp. 000662-000667 ◽  
Author(s):  
Stephani Gulbrandsen ◽  
Joelle Arnold ◽  
Greg Caswell ◽  
Ken Cartmill
Keyword(s):  
Weight Loss ◽  
Operating Conditions ◽  
Accelerated Life Test ◽  
Electrolytic Capacitor ◽  
Time To Failure ◽  
Equivalent Series Resistance ◽  
Aluminum Electrolytic Capacitor ◽  
Critical Weight ◽  
Accelerated Life ◽  
Speed Up

This research compared the lifetime of similar aluminum electrolytic capacitors from different manufacturers using an accelerated life test, which consisted of critical weight loss testing and rate of weight loss testing. In critical weight loss testing, capacitors are perforated to speed up electrolyte evaporation and the equivalent series resistance (ESR) and weight are measured periodically to determine their relationship. In rate of weight loss testing, capacitors are subjected to final operating conditions (i.e. voltage and ripple current are applied) and the weight is periodically measured over the course of 500 hours. After test completion the relationship between ESR and weight loss is used to calculate the critical weight loss that occurs at datasheet-defined failure, which is typically a 200% increase in ESR. The rate of weight loss is extrapolated to the critical weight to estimate a time to failure that can be compared to other capacitors tested using the same accelerated approach. In this research, testing compared 450 V, 68 μF capacitors from Manufacturer A and Manufacturer B, and results indicated Manufacturer A had a significantly longer lifetime. Therefore, capacitors from Manufacturer A are more reliable than capacitors from Manufacturer B.

scholarly journals Analysis and Control of Electrolytic Capacitor-Less LED Driver Based on Harmonic Injection Technique

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3030 ◽  
Author(s):  
Mahmoud Nassary ◽  
Mohamed Orabi ◽  
Manuel Arias ◽  
Emad Ahmed ◽  
El-Sayed Hasaneen
Keyword(s):  
Power Factor ◽  
Low Frequency ◽  
Buck Converter ◽  
Electrolytic Capacitor ◽  
Injection Technique ◽  
Led Driver ◽  
Harmonic Injection ◽  
Output Capacitor ◽  
And Control ◽  
Led Drivers

AC-DC LED drivers may have a lifespan shorter than the lifespan of LED chips if electrolytic capacitors are used in their construction. Using film capacitors solves this problem but, as their capacitance is considerably lower, the low-frequency ripple will increase. Solving this problem by limiting the output ripple to safe values is possible by distorting the input current using harmonic injection technique, as long as these harmonics still complies with Power Factor Regulations (Energy Star). This harmonic injection alleviates the requirements imposed to the output capacitor in order to limit the low-frequency ripple in the output. This idea is based on the fact that LEDs can be driven by pulsating current with a limited Peak-To-Average Ratio (PTAR) without affecting their performance. By considering the accurate model of LEDs, instead of the typical equivalent resistance, this paper presents an improved and more reliable calculation of the intended harmonic injection. Wherein, its orders and values can be determined for each input/output voltage to obtain the specified PTAR and Power Factor (PF). Also, this harmonic injection can be simply implemented using a single feedback loop, its control circuit has features of wide bandwidth, simple, single-loop and lower cost. A 21W AC-DC buck converter is built to validate the proposed circuit and the derived mathematical model and it complies with IEC61000 3-2 class D standard.

scholarly journals Stability analysis of equivalent series resistance of output capacitor in fixed off-time controlled Buck converter

2012 ◽  
Vol 61 (16) ◽  
pp. 160503
Author(s):  
Zhang Xi ◽  
Bao Bo-Cheng ◽  
Wang Jin-Ping ◽  
Ma Zheng-Hua ◽  
Xu Jian-Ping
Keyword(s):  
Stability Analysis ◽  
Series Resistance ◽  
Buck Converter ◽  
Equivalent Series Resistance ◽  
Output Capacitor ◽  
Off Time

Analysis, Design and Control of an Integrated Three-Level Buck Converter under DCM Operation

2019 ◽  
Vol 29 (01) ◽  
pp. 2050011
Author(s):  
Wen-Ming Zheng ◽  
Wen-Liang Zeng ◽  
Chi-Wa U ◽  
Chi-Seng Lam ◽  
Yan Lu ◽  
...  
Keyword(s):  
Output Voltage ◽  
Buck Converter ◽  
Cmos Process ◽  
Maximum Output ◽  
Analysis Design ◽  
On Chip ◽  
Output Capacitor ◽  
And Control ◽  
Voltage Conversion ◽  
Conduction Mode

A three-level buck (TLB) converter has the characteristics of higher voltage conversion efficiency, lower inductor current ripples, output voltage ripples and voltage stresses on switches when compared with the buck converters in continuous conduction mode (CCM). With a TLB converter integrated on a chip, we cannot avoid its discontinuous conduction mode (DCM) operation due to a smaller inductance and load variation. In this paper, we’ll present and discuss the analysis, design and control of a TLB converter under DCM operation, implemented in a 65[Formula: see text]nm CMOS process. Transistor level simulation results show that when the TLB converter operates at 100[Formula: see text]MHz with a 5[Formula: see text]nH on-chip inductor, a 10[Formula: see text]nF output capacitor and a 10[Formula: see text]nF flying capacitor, it can achieve an output conversion range of 0.7–1.2[Formula: see text]V from a 2.4[Formula: see text]V input supply, with a peak efficiency of 81.5%@120[Formula: see text]mW. The output load transient response is 100[Formula: see text]mV with 101[Formula: see text]ns for undershoot, and 86[Formula: see text]mV with 110[Formula: see text]ns for overshoot when [Formula: see text]–100[Formula: see text]mA. The maximum output voltage ripple is less than 19[Formula: see text]mV.

Electrolytic Capacitorless AC/DC LED Driver

2019 ◽  
Vol 28 (12) ◽  
pp. 1950200
Author(s):  
Changyuan Chang ◽  
Xiong Han ◽  
Menglin Wu ◽  
Dadi Zhao ◽  
Hongliang Xu
Keyword(s):  
Input Voltage ◽  
Buck Converter ◽  
Electrolytic Capacitor ◽  
Conduction Time ◽  
Test Results ◽  
Led Driver ◽  
Power Difference ◽  
Load Regulation ◽  
Constant Output ◽  
Conduction Mode

This paper presents electrolytic capacitorless AC/DC LED driver. It adopts Boost–Buck topology, through modulation of the conduction time [Formula: see text] and the change of input current reference, to reduce the instantaneous input and output power difference, so a smaller film capacitor can be used instead of the electrolytic capacitor. Therefore, LED driver power life has been effectively improved. The Buck converter operates in the inductor current discontinuous conduction mode to achieve constant output current by controlling the peak current. The control IC is fabricated in TSMC 0.35-[Formula: see text]m 5-V/650-V CMOS/LDMOS process, and verified in a 72-V/150-mA circuit prototype. The test results show that when the range of input voltage is 175–264 Vac, the efficiency of the system is 83%, the voltage linear regulation is [Formula: see text]%, the load regulation is [Formula: see text]%, and the electrolytic capacitor is replaced by 470-nF CBB capacitor under the condition that the power factor is above 0.7. Therefore, the design of the control chip in the LED driver has a very good application prospect.

Design and Control for the Buck-Boost Converter Combining 1-Plus-D Converter and Synchronous Rectified Buck Converters

2015 ◽  
Vol 6 (2) ◽  
pp. 305
Author(s):  
Jeevan Naik
Keyword(s):  
Output Voltage ◽  
Input Voltage ◽  
Boost Converter ◽  
Buck Converter ◽  
Voltage Source ◽  
Buck Converters ◽  
Power Switches ◽  
Output Capacitor ◽  
And Control ◽  
Conduction Mode

<span>In this paper, a design and control for the buck-boost converter, i.e., 1-plus-D converter with a positive output voltage, is presented, which combines the 1-plus-D converter and the synchronous rectified (SR) buck converter. By doing so, the problem in voltage bucking of the 1-plus-D converter can be solved, thereby increasing the application capability of the 1-plus-D converter. Since such a converter operates in continuous conduction mode inherently, it possesses the nonpulsating output current, thereby not only decreasing the current stress on the output capacitor but also reducing the output voltage ripple. Above all, both the 1-plus-D converter and the SR buck converter, combined into a buck–boost converter with no right-half plane zero, use the same power switches, thereby causing the required circuit to be compact and the corresponding cost to be down. Furthermore, during the magnetization period, the input voltage of the 1-plus-D converter comes from the input voltage source, whereas during the demagnetization period, the input voltage of the 1-plus-D converter comes from the output voltage of the SR buck converter.</span>

Comparison of Dc-Dc SEPIC, CUK and Flyback Converters Based LED Drivers

2020 ◽  
pp. 99-107
Author(s):  
Erdal Sehirli
Keyword(s):  
Integrated Circuit ◽  
Closed Loop ◽  
Input Voltage ◽  
Open Loop ◽  
Current Sensor ◽  
Switching Frequency ◽  
Led Driver ◽  
Advantages And Disadvantages ◽  
Led Drivers ◽  
Conduction Mode

This paper presents the comparison of LED driver topologies that include SEPIC, CUK and FLYBACK DC-DC converters. Both topologies are designed for 8W power and operated in discontinuous conduction mode (DCM) with 88 kHz switching frequency. Furthermore, inductors of SEPIC and CUK converters are wounded as coupled. Applications are realized by using SG3524 integrated circuit for open loop and PIC16F877 microcontroller for closed loop. Besides, ACS712 current sensor used to limit maximum LED current for closed loop applications. Finally, SEPIC, CUK and FLYBACK DC-DC LED drivers are compared with respect to LED current, LED voltage, input voltage and current. Also, advantages and disadvantages of all topologies are concluded.

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