Universal AC Mains Research Articles

An Independently Controlled Two Output Half Bridge Resonant LED Driver

In this research work, an independently controlled two output half-bridge resonant LED driver is proposed. Half bridge series converters will be providing power to two LED lamps. The devices in half-bridge converter are switched at zero voltage using LC resonant circuit. Therefore, switching transition power losses are minimized which increases the LED driver efficiency. Each LED lamp’s ripple current is decreased by adding an inductor in series with it, eliminating the need for an electrolytic capacitor and extending the life of the resonant LED driver. Both regulating and dimming operations use asymmetrical duty cycle (ADC) control. Numerical simulations are conducted to examine the suggested resonant converter topology’s steady state performance as it sources LED applications. Using the OrCAD/PSPICE tool for universal AC mains, 25 W and 29 W LED driver analysis, design, modeling, and simulation are carried out. The proposed driver needs to provide high efficiency even at reduced illumination.

Quasi‐constant bus voltage CrCM boost PFC fed LLC resonant converter in high power LED lighting systems

SummaryThis paper deals with a two‐stage LED (light emitting diode) driver on the basis of front‐end boost converter operating in critical conduction mode (CrCM) and second stage LLC resonant converter for driving an LED lighting load. The boost converter operates in the valley switching mode to reduce switching power loss with less component stress. The ZVS (zero voltage switching) operation of both the half‐bridge semiconductor switching devices reduces the switching losses, which improves the system efficiency. Moreover, to ensure the stability of the DC‐bus voltage, state‐space analysis is also carried out for the CrCM boost converter. The first stage provides the power factor correction (PFC) over the universal AC mains and maintains a constant DC‐bus for the next stage. The second‐stage converter maintains a ripple‐free output voltage to an LED load. This circuit has reasonably minimized the design complexity as compared with single‐stage variable DC‐bus PFC integrated resonant converters and also gives improved efficiency in an isolated configuration. In order to validate the system, a 150‐W prototype is investigated, and experimental findings are analyzed in‐line with theoretical results at universal AC mains.

A Universal Input CrCM Luo Converter With Low-Cost Pilot-Line Dimming Concept for General Purpose LED Lighting Applications

This paper deals with the design and implementation of a Luo converter operating in two different modes with an improved power quality (PQ) and flickerless operation over the universal ac mains for general purpose lighting applications. A cost-effective analog pilot-line dimming concept is incorporated and discussed in detail. The proposed dimming concept offers good PQ, even during dimming, with low cost for the energy efficient lighting solutions. The Bode plot analysis of this proposed Luo converter is presented using state-space analysis to ensure its stability with closed-loop control. The prototype is developed and tested in the laboratory for a 36-W light-emitting diode lamp load with rated current of 700 mA. The measured power factor in case of 30% dimming is 0.97 with total harmonic distortion of 8.7% only. The measured efficiency is 91% at rated ac mains voltage of 230 V.

Power Factor Correction in Modified SEPIC Fed Switched Reluctance Motor Drives

This paper presents a dual output power factor correction (PFC) converter for switched reluctance motor (SRM) drives. Here, a modified single-ended primary inductance converter (SEPIC) is proposed for a wide range of speed control and to achieve PFC at ac mains. The switching frequency of the converter is considered to be 20 kHz. The converter is designed to operate in the discontinuous conduction mode (DCM) of operation, which reduces the size of the output inductor. The DCM mode to obtain PFC also reduces the sensor requirement as compared to the continuous conduction mode (CCM), where two voltage sensors and one current sensor add to the drive cost. The drive is proposed for universal ac mains (90–270 V ac). Simulated and experimental results are demonstrated to validate the performance of the drive during different operating conditions. The input current total harmonic distortion is reduced to comply with an IEC 61000-3-2 standard.

A Highly Efficient Coupled-Inductor SEPIC Topology Based PFC DC–DC Converter for Low Power LED Lighting Systems

ABSTRACTThis paper deals with the design, simulation, and implementation of a single-stage single ended primary inductance converter (SEPIC) power factor correction (PFC) converter-based light emitting diode (LED) driver useful to operate for wide supply voltage variations. The proposed non-isolated SEPIC converter has been chosen to operate in discontinuous conduction mode (DCM) using pulse frequency modulation (PFM) control scheme to control output current through an LED lamp string. The primary focus of this work is to develop an efficient power converter with improved power quality performances for low power LED lighting systems. The modeling, simulation, and implementation of the proposed driver have been carried out for a 28 W LED string load. To confirm the design of the proposed driver, various power quality performance parameters are analyzed which are found well within the norms of international standard IEC 61000-3-2 of class C equipment throughout the universal AC mains.

A PFC Modified Landsman Converter-Based PWM-Dimmable RGB HB-LED Driver for Large Area Projection Applications

In this paper for power factor correction (PFC), a modified Landsman converter is introduced. The application is targeted for high-brightness (HB) projection application with brightness control for HB red–green–blue (HB-RGB) light-emitting diode (LED). A pulse-width modulation (PWM) technique is used for intensity control to achieve brightness control of the LED driver. The proposed PFC converter is used to feed a dual output flyback dc–dc converter that supplies power to the forced cooling unit and the LED module with galvanic isolation. The brightness control of LED is performed by synchronous buck converter. The modified Landsman converter operates in discontinuous output inductor current mode for PFC at universal ac mains. A prototype of the proposed LED driver is experimentally verified. The performance of proposed driver is evaluated at full and light-load condition for universal ac mains (90–265 V) over a full range of brightness. The power quality parameters are found within the acceptable limits of harmonic standard IEC 61000-3-2 for universal ac mains.

High power factor and low total harmonics distortion using critical conduction mode boost converter-fed light-emitting diode driver

Summary This article presents a critical conduction mode (CRM)–based power factor correction (PFC) converter for multistring light-emitting diode (LED) driver. The application is targeted for high power projection application with brightness control of red-green-blue LED module. A pulse width modulation (PWM) technique is used for lighting control to achieve required brightness without compromising the efficiency (overall 82%) and power quality. The CRM boost PFC converter is used to feed a dual output flyback DC-DC converter, which supplies power to the forced cooling unit and the LED modules with galvanic isolation. The brightness control of LED is performed by synchronous buck converter using current PWM modulation. The CRM boost converter–based PFC converter is designed to operate in critical inductor current mode at universal AC mains. A prototype of proposed PFC converter–based LED driver is developed and experimentally verified. The power quality parameters of the proposed LED driver are evaluated at rated and light load conditions for universal AC mains (90–265 V) with brightness control. The power quality parameters are found within acceptable ranges of international harmonic standard IEC 61000-3-2 Class C for lighting systems.

Power quality improvement using bridgeless‐Landsman converter for LED driver

This study presents a bridgeless-Landsman converter for power factor correction (PFC) of light-emitting diode (LED) driver. It is targeted for high brightness LED driver with pulse-width modulation dimming for brightness control. This PFC converter is used to feed dual output flyback DC–DC converter which supplies power to the LED module and forced cooling unit with galvanic isolation. The brightness control of LED is performed by three independent synchronous buck converters. The PFC converter is designed to operate in discontinuous input inductor current mode for inherent PFC at universal AC mains. A prototype of the proposed PFC LED driver is developed to validate experimentally the design and model. The power quality indices of the proposed LED driver are evaluated at rated and light load conditions for universal AC mains (90–265 V) with brightness control. The power quality indices are found within acceptable range of international harmonic standard IEC 61000-3-2 for universal AC mains.

A Novel Wall-Switched Step-Dimming Concept in LED Lighting Systems Using PFC Zeta Converter

This paper presents the design, simulation, and implementation of a non-isolated discontinuous conduction mode operated Zeta-converter-based light-emitting diode (LED) driver with the novel wall-switched step-dimming concept to achieve power quality improvement at universal ac mains. The power-factor-corrected Zeta converter maintains constant output current to an LED load of 26 W and conserves the power quality requirements as per IEC 61000-3-2 for class C equipment with high efficiency. Moreover, to obtain cost benefit and size reduction, this converter utilizes reduced control circuitry for general-purpose LED lighting solutions. A cost-effective single-level dimming concept is implemented with current injection technique using a Zeta converter. A prototype is developed using AP1682, which utilizes pulse frequency modulation technique to regulate the output current for improving the input power factor and low total harmonic distortion (THD) of the input current. At full load and rated voltage of 220 V, the measured input power factor is 0.993 and current THD is 2.81% with an efficiency of 90.51%.

Constant on time controlled zero voltage switching electronic ballast with power quality improvement

This study deals with the design, modelling and implementation of unity power factor (UPF) boundary conduction mode (BCM)-based electronic ballast for a T8, 36 W fluorescent lamp. In low power applications, BCM-based boost converter is widely used because of the low inductor value, however, because of zero crossover distortion, achieving a total harmonic distortion of <10% is difficult for universal AC mains. In proposed electronic ballast, UPF has been achieved at universal AC mains by using a boost power factor corrected converter operating in BCM with constant on time control. The achieved constant DC-link voltage is converted into high frequency AC voltage using a quasi-half bridge series resonant inverter to initiate the discharge and also to drive the fluorescent lamp with constant current. The modelling and simulation of the proposed topology have been performed using sim power system tool-boxes in MATLAB-Simulink environment. The switching losses have been reduced by achieving zero voltage switching at an operating switching frequency of 46 kHz. Different evaluated parameters have been found as per the international standard IEC61000-3-2 of class C regulations.

An Adjustable-Speed PFC Bridgeless Buck–Boost Converter-Fed BLDC Motor Drive

This paper presents a power factor corrected (PFC) bridgeless (BL) buck-boost converter-fed brushless direct current (BLDC) motor drive as a cost-effective solution for low-power applications. An approach of speed control of the BLDC motor by controlling the dc link voltage of the voltage source inverter (VSI) is used with a single voltage sensor. This facilitates the operation of VSI at fundamental frequency switching by using the electronic commutation of the BLDC motor which offers reduced switching losses. A BL configuration of the buck-boost converter is proposed which offers the elimination of the diode bridge rectifier, thus reducing the conduction losses associated with it. A PFC BL buck-boost converter is designed to operate in discontinuous inductor current mode (DICM) to provide an inherent PFC at ac mains. The performance of the proposed drive is evaluated over a wide range of speed control and varying supply voltages (universal ac mains at 90-265 V) with improved power quality at ac mains. The obtained power quality indices are within the acceptable limits of international power quality standards such as the IEC 61000-3-2. The performance of the proposed drive is simulated in MATLAB/Simulink environment, and the obtained results are validated experimentally on a developed prototype of the drive.

A PFC Based BLDCM Drive for Low Power Household Appliances

This work presents a low cost PFC (Power Factor Correction) based BLDCM (Brushless DC Motor) drive targeting low power household appliances. Development of a highly efficient BLDCM drive with minimum amount of sensing requirement is the primary objective of this work. The switching losses in the VSI (Voltage Source Inverter) feeding BLDCM is reduced by electronically commutating the BLDCM and controlling its speed by controlling the voltage of the DC bus. A PFC buck-boost converter is used as a front-end converter due to its simplicity in design, minimum number of component count and its ability to buck and boost the voltage to control the speed over a wide range. The PFC buck-boost converter operating in DICM (Discontinuous Inductor Current Mode) is used for the control of DC bus voltage. An inherent PFC is achieved for variation of speed over a wide range at universal AC mains (90–265 V). The obtained PQ (Power Quality) indices are within the recommended limits of international PQ standards IEC 61000–3-2. The performance of proposed BLDCM drive is simulated in MATLAB/Simulink environment and validated experimentally on a developed prototype of the drive.

A PFC-Based BLDC Motor Drive Using a Canonical Switching Cell Converter

This paper presents a power factor correction (PFC)-based canonical switching cell (CSC) converter-fed brushless dc motor (BLDCM) drive for low-power household applications. The speed of BLDCM is controlled by varying the dc-bus voltage of voltage source inverter (VSI). The BLDCM is electronically commutated for reduced switching losses in VSI due to low-frequency switching. A front-end CSC converter operating in discontinuous inductor current mode (DICM) is used for dc-bus voltage control with unity power factor at ac mains. A single sensor for dc-bus voltage sensing is used for the development of the proposed drive, which makes it a cost-effective solution. A prototype of the proposed configuration is developed, and its performance is validated with test results for the control of speed over a wide range with a unity power factor at universal ac mains.

Buck converter‐based power supply design for low power light emitting diode lamp lighting

This study deals with the analysis and implementation of an HPF (high power factor) single-stage, single switch buck converter-based power supply design for an LED (light emitting diode) lamp load of 13 W operated at the universal ac mains. In general purpose lighting applications, a buck converter is a good candidate for power factor correction with low component count and reduced cost. In low-power lighting, it is a tough task to control the THD i (total harmonic distortion) of ac mains current under the limits of strict international standards such as IEC-61000-3-2 with universal ac mains for class D equipments. In the proposed optocouplerless topology, HPF operation at input ac mains is achieved by operating the buck ac-dc converter in continuous conduction mode. The design, modelling and simulation of the proposed topology are executed using MATLAB-Simulink and sim-power system toolboxes. A prototype of the power supply for LED lamp is developed for multiple LEDs connected in series configuration. The efficiency of the proposed LED lamp driver is observed as 83.76% at rated voltage of 220 V and the THD of ac mains current less than 17.27% for a wide range of voltages of 90-270 V.