Power Factor Correction Converter Operating Research Articles

An Improved Digital Algorithm for Boost PFC Converter Operating in Mixed Conduction Mode

This article proposes an improved digital algorithm based on predictive control for the operation of a boost power factor correction (PFC) converter in the mixed conduction mode (MCM). The proposed MCM algorithm comprises of a proposed digital conduction mode detection method, a proposed predictive discontinuous conduction mode (DCM) average current controller, a proposed digital compensation technique in DCM to account for the initial nonzero inductor current during switch turn-on and also a predictive continuous conduction mode (CCM) average current controller. The proposed algorithm flow is computationally efficient with no additional sensor/circuit requirements and ensures low harmonic content in the input current. The proposed MCM algorithm is verified experimentally on a 300-W boost PFC converter hardware prototype for converter operation in MCM, pure DCM, and pure CCM within a half line cycle. The proposed MCM algorithm is evaluated experimentally in terms of current tracking, current harmonics, and computation times.

A Dimmable Offline LED Driver With OOK-M-FSK Modulation for VLC Applications

This paper proposes a visible light communication (VLC) system consisting of a single-stage buck–boost power factor correction converter operating in the discontinuous conduction mode with dimming capability. Additionally, this paper proposes the on – off M-frequency shift keying modulation for the VLC system. This modulation allows for the transmission of more than a single bit for each switching period without affecting the dimming characteristics of the light-emitting diode luminaire. The design of the whole system is discussed in detail, including both transmitter and receiver modules. A 20-W laboratory prototype was built in order to verify the proposed modulation scheme. The experimental evaluation showed a good performance of the transmitter, which was able to perform simultaneously the desired functions, namely power factor correction, dimming, and data transmission. The receiver also achieved the desired performance with a low bit error rate (BER). The results showed that the proposed system was able to transfer data between emitter and receiver with a bit rate of 1.11 Mb/s at a frequency of up to 375 kHz over a distance of 10 m, and with a BER lower than $10^{-3}$ under the influence of external lighting sources with illuminance levels up to 500 lx.

Simple digital algorithm for improved performance in a boost PFC converter operating in CCM

In power factor correction (PFC) converters, achieving both good steady-state input current waveform and fast output dynamic response is a challenge. This is due to the effect of the double-line frequency ripple present in the sensed output voltage signal which tends to distort the reference current applied to the current controller, thus leading to a distorted input current waveform. Low bandwidth (BW) voltage loop designs to reduce this input current distortion make the output dynamic response very sluggish. A digital control algorithm for the estimation of the average value of the sensed output voltage is proposed in this study to achieve low total harmonic distortion input current and fast dynamic response with a higher BW voltage loop. The proposed algorithm is computationally less intensive and requires no additional sensors or circuitry. The effectiveness of the proposed control algorithm is validated through simulation and experimental tests on a 300 W boost PFC converter prototype operating in continuous conduction mode.

Optimum Third Current Harmonic During Nondead Zone and Its Control Implementation to Improve PF for DCM Buck PFC Converter

A buck power factor correction (PFC) converter is widely used in low-power applications for its high efficiency in the entire universal input voltage range. However, because of the inherent dead zone, the input power factor (PF) is not high. A buck PFC converter operating in a discontinuous conduction mode is introduced. When the duty cycle is constant during the line cycle, the input current contains a large amount of negative third harmonic, especially at a low input voltage. By proposing an optimum third harmonic injection during the nondead zone and its control implementation, a higher PF and a lower output voltage ripple within the entire universal input voltage range are achieved. The experimental verifications are carried out on a 120-W prototype with universal input.

Effect of intermediate capacitance on slow‐scale instability of Cuk power factor correction converter operating in discontinuous capacitor voltage mode

Due to features of near-unity power factor, soft turn-off switching and low switch current stress, Cuk power factor correction (PFC) converter operating in discontinuous capacitor voltage mode (DCVM) has attracted much attention. However, it is found that with the increase of intermediate capacitance, slow-scale instability occurs in voltage mode control (VMC) DCVM Cuk PFC converter. In this study, a simplified model for VMC DCVM Cuk PFC converter is established, upon which the effect of intermediate capacitance on the slow-scale instability and the corresponding bifurcation behaviours are studied by using harmonic balance method and Floquet theory. Furthermore, the stability boundaries in terms of the intermediate capacitance under different load resistance and input voltage are given, which is helpful for parameter design of VMC DCVM Cuk PFC converter. Finally, numerical simulations and experimental results are provided to verify the analysis results.

DSP-Based Control of Tri-State Boost PFC Converter with High Input Power Factor for Wide Range of Load Variations

Tri-state boost power factor correction (PFC) converter operating in pseudo-continuous-conduction mode (PCCM) is analyzed in this paper. The connection of power switch in parallel with inductor makes the boost converter operate in PCCM, which provides an additional degree of control freedom by inductor current freewheeling operation mode. Compared with boost PFC converter operating in continuous conduction mode (CCM) and discontinuous conduction mode (DCM), tri-state boost PFC converter extends the load range and is therefore more suitable for wide range of load variation. However, for universal input applications, the input power factor (PF) of the tri-state boost PFC converter is relatively low when the sinusoidal reference current control strategy is used. To improve the PF over the whole input voltage range, the input current and PF expressions of the tri-state boost PFC converter is derived and the non-sinusoidal reference current control strategy is proposed. A 400 W prototype of the tri-state boost PFC converter is built by using digital signal processing (DSP) as the controller. The experimental results verify the analysis results.

Digital DCM Detection and Mixed Conduction Mode Control for Boost PFC Converters

This paper presents a novel mixed conduction mode (MCM) digital controller with a digital signal processor (DSP)-based discontinuous conduction mode (DCM) detection technique to realize total harmonic distortion (THD) and power factor improvements in boost power factor correction (PFC) converters operating in both continuous conduction mode (CCM) and DCM during a single ac line half-cycle. By using the integrated comparators found on many DSPs, simplification and cost-reductions over existing DCM and zero-current detection methods are made possible. Additionally, performance improvements over a conventional CCM digital control technique are possible with simple software modification, and can be extended to existing boost PFC converter designs provided a compatible DSP is present. At an output power of 98 W, an experimental 650 W boost PFC converter operating in the MCM controlled by a TMS320F28035 provides a THD reduction of 40.2% and power factor improvement of 1.5% over a conventional digital controller.

High‐efficiency two‐switch tri‐state buck–boost power factor correction converter with fast dynamic response and low‐inductor current ripple

Two-switch tri-state buck-boost power factor correction (PFC) converter operating in pseudo-continuous conduction mode is proposed and analysed in this study. Different from tri-state boost PFC converter, the proposed two-switch tri-state buck-boost PFC converter does not need additional power switch to provide the additional degree of control freedom. Therefore it does not increase the complexity and affect the power conversion efficiency of the PFC converter as in the case of tri-state boost PFC converter. For the proposed two-switch tri-state buck-boost PFC converter, the current control loop and voltage control loop are decoupled, a simple voltage control loop with faster dynamic response can be designed to realise output voltage regulation and the additional degree of control freedom introduced by inductor current freewheeling stage helps to achieve unity power factor control. The operation principle, the input current, the inductor current ripple, the switch component stress and the small-signal characteristics of the proposed two-switch tri-state buck-boost PFC converter are analysed. The simulation and experimental results show that the proposed two-switch tri-state buck-boost PFC converter benefits with fast dynamic response, high-efficiency and low-inductor current ripple over single-switch buck-boost PFC converter or two-switch buck-boost PFC converter operating in continuous conduction mode and discontinuous conduction mode.

Input Differential-Mode EMI of CRM Boost PFC Converter

In this paper, the differential-mode (DM) electromagnetic interference (EMI) noise of a single-phase boost power factor correction converter operating in critical current mode was analyzed. The DM noise spectra are calculated based on the mathematical model of EMI receiver and the required corner frequencies of DM filter are obtained. It can be seen that the minimum corner frequencies are determined by the maximum noises at 150 kHz. With the relation between the magnitude of the inductor current ripple and the DM noise, the characteristics of noise at 150 kHz are obtained by analyzing the current ripple magnitude at 150 kHz; thus, the worst conditions which have the maximum noise value are figured out. Meanwhile, the maximum noises at 150 kHz for different input voltages are identical, so the DM filter can be designed based on one worst spectrum at one input voltage without testing the spectra in other conditions.

Distortion Behavior Analysis of General Pulse-Width Modulated Zeta PFC Converter Operating in Continuous Conduction Mode

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.

A Novel PCCM Boost PFC Converter With Fast Dynamic Response

A novel pseudo-continuous conduction mode (PCCM) boost power-factor-correction (PFC) converter and its corresponding control strategy are proposed in this paper. Connecting a power switch in parallel with the inductor makes the boost converter operate in PCCM, which provides an additional degree of control freedom to realize PFC control. Therefore, a simple and fast voltage control loop of the PCCM boost PFC converter can be designed to realize output-voltage regulation. The additional degree of control freedom introduced by inductor current freewheeling operation of the PCCM boost PFC converter has been exploited through the dead-zone control technique, which can be dynamically adjusted in accordance with the output-voltage ripple. Compared with continuous conduction mode (CCM) boost PFC converter, the controller of the proposed PCCM boost PFC converter is much simpler. Moreover, the PCCM boost PFC converter benefits with reduced inductor-current ripple and improved power factor compared with boost PFC converter operating in discontinuous conduction mode (DCM). Analysis, simulation, and a 400-W prototype of the PCCM boost PFC converter have been presented and compared with those of boost PFC converters operating in conventional CCM and DCM. The results show that the dynamic response of the PCCM boost PFC converter is significantly faster than the existing boost PFC converter.