A novel tri-state boost PFC converter with fast dynamic performance

For most actual power applications, power-factor correction (PFC) converters usually operate in the stable continuous conduction mode (CCM), but input current distortion will occur as long as these converters operate in oscillatory condition. This distortion usually manifests itself as a local oscillation within one line cycle. Typically, a Zeta PFC converter under the general pulse-width modulated (GPWM) control possesses high performance, and requires simpler control circuitry with fewer external components. However, due to the large-signal nonlinearity of the GPWM controller, the dynamic analysis and modeling of the input current distortion in its PFC converters remains vacant. In this paper, a large-signal average SPICE model is derived to capture the time-domain waveforms of the input current and output voltage. A power-balance approach for the PFC converter operating in CCM is developed, which can predict the steady-state values of the converters by using the Fourier series expansion. Analysis of the distortion behavior is provided in terms of the proposed model and the unbalanced power transfer mode. Experimental results are presented to verify the proposed method.

This paper proposes an improved modulated carrier control method for a continuous conduction mode (CCM) power factor correction (PFC) boost converter. The proposed method allows precise sinusoidal line current shaping for a boost PFC converter operating in CCM. This is accomplished by simply comparing the compensated modulated carrier signal with the switch current information, such that the current loop compensation is eliminated and multiplier is not required. Also, the proposed control method overcomes the instability problem of conventional modulated carrier control around the zero crossings of the line voltage at light load. The performance of the proposed control method is experimentally verified on a 300 W PFC converter.

Due to the ever-expanding use of light emitting diodes (LED) lamps and the necessity of constant current to operate properly, a drive circuit is required for these types of lamps. Also, power factor correction (PFC) to eliminate harmonics, is required and must be included in these types of drivers based on the existing standards. Soft switching can effectively reduce the switching losses and electromagnetic noise. Consequently, high switching frequency operation is possible which reduces the converter weight and size, effectively and high power density is achieved. In this paper, continuous conduction mode (CCM) operation of a single-stage boost-flyback converter with active-clamp for LED driver applications is introduced. Its CCM operation leads to low input current ripple which reduces the input filter volume effectively. Also, low voltage and current stresses on the components are obtained. As a result, the converter can be used for high power applications compared with previously proposed discontinuous conduction mode (DCM) operation. Theory, simulation as well as practical results are presented below.

This paper discusses experimental validation of semi-bridgeless boost rectifier (SBBR) operation of continuous conduction mode (CCM) & discontinuous conduction mode (DCM) for power quality improvement in uninterrupted power supply (UPS) system. The double stage conversion in UPS attenuates power quality at the input side and output configuration of the system. Many researchers have proposed the improvement of power quality with CCM and DCM operations for ac-dc conversion stage in bridge and bridgeless rectifier, but there is lack of knowledge about their performance and drawbacks of CCM and DCM operation with SBBR topology. This paper focuses on experimental analysis of SBBR topology operating in CCM and DCM under different load ranges. The performance of power quality factors and efficiency of SBBR operating in CCM and DCM are addressed. To study the stability analysis of SBBR operation in CCM and DCM, a comprehensive small signal model is derived by analyzing the inductor current waveforms. PSCAD simulations have obtained theoretical study of SBBR with CCM and DCM operations and experimental validation is carried out through FPGA Spartan 3A processor.

This paper presents a control method for three-phase inverter under grid fault condition based on a novel critical conduction mode (CRM)-based soft-switching modulation. In the soft-switching modulation, one phase is clamped to dc bus, other two phases operate in CRM and discontinuous conduction mode (DCM), respectively. The soft-switching technique with silicon carbide (SiC) power devices allows the inverter to operate at hundreds of kHz with high efficiency by reducing switching loss. In order to extend the modulation scheme to more practical cases, behavior of the inverter under grid fault conditions, specifically voltage sag, is investigated. During voltage sag, the grid voltage becomes unbalanced requiring unbalanced ac current reference for the avoidance of output active power oscillation. With the unbalanced grid voltage and ac current reference, continuous conduction mode (CCM) operation occurs where DCM operation is intended leading to high turn-on loss. To eliminate the CCM operation and reduce the turn-on loss, an improved modulation technique is proposed by using off-time extension concept in CRM phase. In this paper, how the CCM operation appears under grid fault condition, and details of the proposed control are discussed. Performance of the proposed control method is validated experimentally with SiC-based three -phase inverter laboratory prototype.

The use of power factor correction (PFC) converters is widely discussed and considered for most off-line power supplies. For low power applications, boost PFC converters operated in discontinuous conduction mode (DCM) or boundary conduction mode (BCM) mode are usually employed. The main advantage of BCM mode is the reduction of reversal recovery loss of diode and simple control, especially at the high-line light-load condition. In this paper, a digital-controlled method for boost PFC operating under boundary conduction mode without input voltage sensing is proposed. The digital PI controller voltage is used to determine the constant on-time period and the comparator block inside the DSP controller is employed to detect the zero-crossing of inductor current for turning on the main switch. Therefore, the size and cost are reduced significantly. A 200W boost PFC prototype is implemented and tested to verify the feasibility of the proposed control scheme.

The operation of the two-phase interleaved CRM Boost power factor correction (PFC) converter with coupled inductors is analyzed in this paper. Since the equivalent inductance varies with the switching mode and duty cycle, the current mode control method should be adopted to achieve PFC rather than the voltage mode control. The switching frequency is derived, and the self inductance is discussed in term of the minimum switching frequency, which should be higher than 20 kHz to avoid acoustic noise. The design methodology of the coupled inductors is presented as well. Compared to the discrete inductors, the coupled inductor has small size and low copper usage, so the power density of the PFC converter can be increased.

This paper presents a small-signal analysis of the pulse-width modulated (PWM) boost dc-dc converters operating in continuous-conduction mode (CCM) and subject to complex impedance load. Using the existing knowledge on the small-signal model of the boost converter obtained through the circuit averaging approach, this paper presents an extended analysis of the small-signal transfer functions, under the influence of resistive and inductive load impedances. The expressions for the control-to-output, input-to-output voltage transfer functions, and the output impedance of the boost converter operating in CCM are derived. The characteristics of these transfer functions are analyzed and the effect of the added inductance on the location of poles and zeros is discussed. It is shown that the inherent right-half plane (RHP) zero shifts to the left-half of the s-plane, when the load inductance is increased beyond a specific value. The theoretical results are validated by simulations of a boost converter with suitable design specifications.

The overall dynamics of power-factor-correction (PFC) boost converter, including the fast-scale instability, the low-frequency stable periodic operation, the low-frequency bifurcation and chaos, are investigated by using the combined continuous conduction mode (CCM) and discontinuous conduction mode (DCM) model. It is conventionally assumed that the converter operates in CCM in the design and analysis process of a PFC boost converter, which prevents us to understand the overall dynamics of the converter. It has been pointed out that the DCM can occur in the PFC boost converter, especially, in the light load condition. Therefore, the DCM model has to be included to analyze this PFC converter to cover the possible DCM operation. The unified model for describing the overall dynamics of the PFC boost converter is derived, which can be used to analyze the overall dynamics uniformly. By using the proposed combined model, the fast-scale instability can be detected. At the same time, the low-frequency bifurcation diagram is derived by proposed model, which makes the route from period-double bifurcation to chaos clear. The overall dynamics derived from the proposed method is verified by the experimental results

The three-level boost power factor correction (PFC) converter has advantages of lower inductor current ripple and lower switch withstanding voltage compared with the boost PFC converter. Interleaved pulsewidth modulation had been used in the multiphase boost PFC converter. In the literature, interleaved current sensorless control (ICSC) for the multiphase boost PFC converters had been proposed. In this paper, the behavior of the three-level boost PFC converter is first analyzed. The results show that three-level converter has the same average equation as the interleaved boost PFC converter. Then, ICSC is modified for the three-level boost PFC converter with considering the voltage imbalance and the zero-crossing current distortion. The proposed modified ICSC (MICSC) is implemented in a field-programmable gate array board. Simulation results and experimental results are also provided to validate the proposed MICSC.

The flyback converter is widely used in modern power conversion systems due to its simple topology, single switch, low component count, and inherent galvanic isolation. This paper investigates the performance characteristics of flyback converters by analyzing their operation in Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM), with particular emphasis on voltage spike behavior. The main contribution of this study is the development of a mathematical model that correlates the operating mode (CCM or DCM) with the voltage spike across the power switch. In addition, the study examines the impact of duty cycle variations on voltage spike behavior. The results show that, for comparable operating conditions and moderate duty cycles, CCM operation generally results in lower voltage spikes than DCM due to reduced peak magnetizing current, while at higher duty cycles and load levels, CCM may exhibit increased voltage stress. The proposed approach was validated through MATLAB/Simulink simulations and a scaled-down experimental prototype. A proportional integral (PI) controller is implemented in simulation to ensure regulated output voltage under practical operating conditions. The results demonstrate that optimizing the duty cycle and accounting for the influence of conduction mode can enhance the reliability of flyback converters, making them suitable for applications requiring galvanic isolation and cost-effective solutions.

Primary side regulation (PSR) technology has the characteristics of lower cost and standby power losses. However, there is no algorithm suitable for discontinuous conduction mode (DCM) and continuous conduction mode (CCM) operations of primary side control for flyback converter because of the difficulty in estimating the output voltage correctly. In this paper, a PSR control algorithm suitable for DCM/CCM flyback converter is proposed and implemented with digital micro controller. The voltage drop on the secondary winding and output diode at CCM operation is compensated by sensing the secondary side current at the instant when primary side switch is being turned-on. The secondary side current is zero at the voltage sensing instant and equal to the current at the instant when primary side switch is being turned-on as flyback operated at DCM. In addition, the proposed algorithm can be used to regulate either the output voltage or current very well. An experimental prototype with 150 W rated power is built to verify the feasibility of the proposed control. Experimental results show that the output voltage can be controlled with error less than 0.25%, and the output current error is less than 5%. The conversion efficiency is up to 92.8%.

Nowadays electric vehicles (EVs) are the most popular due to their cost-effectiveness and as an alternative to traditional petroleum fuel-based vehicles. When EV is charged from the utility grid conventional AC-DC converter act as a nonlinear load drawing peaky current from a supply and results in a very poor input power factor. The converter present at the input AC side which converts alternating current (AC) into direct current (DC), a crucial part of an electric car battery charging system, must have high efficiency. The topologies for use at the ac input side to convert ac into dc for EV battery charging are evaluated in this paper. The focus is on boost converter-based power factor correction converters, which provide excellent efficiency, good power factor, and affordable pricing. Traditional boost power factor correction converter, interleaved boost power factor correction converter, and bridgeless totem pole boost power factor correction converter are the topologies under investigation. The performance of all these topologies is simulated using Matlab/Simulink. All converters give the output of 400 V DC from a universal ac input voltage with a Total Harmonic Distortion (THD) percentage level that satisfies the IEEE Standards are provided with their simulation results.

A reduced sensor based bridgeless boost (BLB) power factor correction (PFC) converter fed full-bridge inductor–inductor capacitor (FBLLC) converter for electric vehicle (EV) charging, is presented in this article. This converter is a twin stage converter, where the first stage is a PFC-BLB converter operating in continuous conduction mode of its boost inductors, and the second stage is an FBLLC converter, which converts the output voltage of the PFC-BLB converter to an isolated low voltage for constant current/constant voltage (CC/CV) charging of an EV battery. The BLB converter is switched at fixed frequency using pulsewidth modulated control, whereas FBLLC converter employs a pulse frequency modulation control to enable CC/CV charging of EV battery. An experimental prototype of EV charger is developed and the digital control of PFC-BLB and FBLLC converter, is implemented using a 32 bit <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$TMS320F28035$</tex-math></inline-formula> digital signal processor to charge an EV battery with a maximum power of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2.7\text{ kW}$</tex-math></inline-formula> and a current of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$50\text{ A}$</tex-math></inline-formula> .

With the increasing application of photovoltaic, the micro-inverter with interleaved flyback module operating in continuous conduction mode (DCM) and discontinuous conduction mode (DCM)is more popular. However, its difficult to control output current of interleaved flyback micro-inverter because the transfer function has right-half-plane (RHP) zero in CCM and low gain in DCM. To solve this problem, considering primary current and the output CL filter, a novel third-order model in DCM operation is proposed for theoretical analyzing. Then Quasi-Proportional-Resonant (Q-PR) controllers is adopted to apply the dual-mode control in flyback inverter, since the Q-PR controller can reduce the steady-state current tracking error, reject disturbance rejection capability, and improve transient performance. The effectiveness of the control method and the proposed model are validated by MATLAB/SIMULINK.