Mode Boost Power Factor Correction Research Articles

Maximum Efficiency Average Current Controller Based on a Comprehensive Charge Rate Model for DCM Boost PFC Converter

This article investigates modeling and control approaches to optimize the efficiency and power factor for discontinuous conduction mode boost power factor correction converters. First, with detailed consideration of parasitics and GaN HEMT transients, the input and output charges of the converter are exactly derived, where the rate forms the comprehensive charge rate (CCR) model. Second, based on the CCR model, the overall efficiency is derived. Since the overall efficiency is only related to the input voltage, output voltage, and switching on -time, an optimal on -time is calculated to achieve the maximum efficiency. Furthermore, with the optimal on -time, a maximum efficiency average current (MEAC) controller is proposed to regulate the input current while maintaining the maximum efficiency. With the predefined optimal on -time, a switching cycle modulation method is adopted to regulate the input current as sinusoid, which improves the power factor to unity. Finally, effectiveness of the MEAC control strategy is verified by simulations and experiments. Compared with conventional constant on -time control, it achieves an optimized efficiency and power factor over a large operation range.

Heteromagnetic Swinging Inductor and Its Application for Power Factor Correction Converters

A variable inductor concept based on a magnetic structure consisting of composite of magnetic materials is introduced to meet the designed inductance function of current. A design of the inductor, termed heteromagnetic swinging inductor (HMSI), was fabricated using a toroid core with a gap that was filled by a custom-developed low-permeability magnetic powder + polymer material. Having the gap filled with the magnetic material allowed for greater flexibility in L–I design with added benefit of low fringe field. The analytical model of HMSI was derived and verified by simulation. And the step-by-step design of arbitrary L–I curve HMSI was posted. We applied this swinging inductor to a critical conduction mode boost power factor correction converter to reduce its switching frequency variation range. First, the required L–I curve of the HMSI needed for narrow range of switching frequency was calculated. Then, the HMSI core structure consisting of two magnetic materials was designed. Finally, a prototype of the HMSI was fabricated and tested. Experimental result showed that for a 110-Vrms input, the converter with the HMSI had a switching frequency variation factor, defined as Δ f / f min, six times less than that of the converter using a linear inductor.

Quasi-Fixed Switching Frequency Control of CRM Boost PFC Converter Based on Variable Inductor in Wide Input Voltage Range

With traditional constant on-time control, the switching frequency variation range of critical conduction mode boost power factor correction converter is large during a half line cycle, not to mention the wide range of input voltage's rms value. For this issue, this article puts forward a quasi-fixed switching frequency control, which combines the variable on-time and variable inductor technology together. Furthermore, a lower output voltage ripple and a higher efficiency are obtained. In spite of the power factor decrease, the input current harmonics still satisfy the IEC61000-3-2 Class D limits. The detailed theoretical analysis and experimental results are presented in this article.

A Current Reshaping Strategy to Reduce Parasitics-Induced Current Distortion in Discontinuous Conduction Mode Boost Power Factor Correction Converter

This article reveals parasitics-induced current distortion (PCD) effect in discontinuous conduction mode boost power factor (PF) correction (PFC) converter. With consideration of parasitics, accurate inductor current is derived through total differential functions of line voltage, output voltage and duty cycle. Furthermore, the proposed current model is used to analyze PFC converter under conventional sensorless average current mode (SACM) control, which is achieved by a variable duty cycle. It is found that parasitics have considerable influence to the input current, and PCD leads to a degraded PF. In order to solve this issue, a current reshaping strategy is proposed to reduce the PCD phenomenon. Based on the damped current equations, a compensation gain is derived to reshape the input current, which reduces the current damping and distortion caused by parasitics. Both the PCD phenomenon and the current reshaping strategy are verified by simulations and experiments.

Optimum Boundary Inductance Control Concerning Limited PF for a DCM Boost PFC Converter

The discontinuous conduction mode boost power factor correction converter features zero-current turn- on for the switch, no reverse recovery in diode, and constant frequency operation. With traditional constant duty ratio control, the power transfer in each switching cycle exhibits great difference during a half-line cycle. Consequently, the peak and root mean square values of the inductor current are large, the same goes for the switch and diode. This increases not only the current stress of the power components but also the conduction and switching turn- off loss, and lowers the efficiency of the converter. Introducing third and fifth harmonics into the input current and varying the duty cycle correspondingly can reduce the aforementioned power transfer difference, and provide huge space for the increment of boundary inductance as well. An optimum boundary inductance control concerning limited power factor (PF) is proposed in this paper. For the maximum boundary inductance of the converter within wide input voltage range, the optimum harmonics amounts are analyzed and figured out. The proposed method brings about efficiency improvement, output voltage ripple reduction, and PF increase as well, especially at high input voltages. A prototype has been built and the experimental results are presented to show the validity of the scheme.

Three‐phase ripple free DCM boost converter with low THD

High total harmonic distortion (THD) and ripple of input current are the two main disadvantages of a single switch discontinuous current mode boost power factor correction (PFC) converter. In this study, THD and input current ripple of conventional DCM boost converter are improved. Reduction of input current THD is achieved by reducing the discharge time of input inductors using magnetic switch concept. Input inductors currents are discharged with a voltage equal to twice of output voltage instead of the output voltage. Also, high input current ripple in discontinuous conduction mode (DCM) operation is solved by using an additional input inductor-capacitor (LC) filter in the conventional converter. This will result in extra weight and volume of the converter. To eliminate the required additional inductors for implementation of the mentioned input LC filter, a ripple cancellation cell using coupled inductors is used and by adjusting mutual inductance in a proper manner, very low input current ripple is achieved. Results from a 400 W prototype converter are presented. Input current THD is below 8% for a wide range of input voltage. Furthermore, the efficiency of the proposed converter is compared with conventional DCM boost PFC converter under the same input current THD. Although the proposed converter applies two switches, the total switching and conduction losses are reduced considerably.

A Digital Phase Leading Filter Current Compensation (PLFCC) Technique for CCM Boost PFC Converter to Improve PF in High Line Voltage and Light Load Conditions

This paper proposes a digital phase leading filter current compensation (PLFCC) technique for a continuous conduction mode boost power factor correction to improve PF in high line voltage and light load conditions. The proposed technique provides a corrected average inductor current reference and utilizes an enhanced duty ratio feed-forward technique which can cancel the adverse effect of the phase leading currents caused by filter capacitors. Moreover, the proposed PLFCC technique also provides the switching dead-zone in nature so the switching loss can be reduced. Therefore, the proposed PLFCC can significantly improve power quality and can achieve a high efficiency in high line voltage and light load conditions. The principle and analysis of the proposed PLFCC are presented, and performance and feasibility are verified by experimental results from the universal input (90–260 $V_{\rm AC}$ ) and 750 W–400 V output laboratory prototype.

Control method for improving the response of single‐phase continuous conduction mode boost power factor correction converter

Continuous conduction mode power factor correction AC–DC converters are widely employed as the front stage in power supplies with medium or high output power. The second-order reactive input power in single-phase systems causes second-order ripple in the DC-link voltage. The speed of voltage regulation is thus limited by the second-order frequency in seeking to achieve low distorted input current. This study presents a fast second-order voltage estimation method, wherein an integrator is used for the estimation of second-order voltage ripple to obtain rapid voltage feedback without ripple and thereby cope with the limitations imposed by the second-order frequency. This approach greatly expands the bandwidth of the voltage control loop beyond the second-order frequency while reducing the total harmonic distortion associated with the input current. This also makes it possible to reduce the DC capacitance to reduce costs. The authors opted for full digital control using a TI F28335 DSP IC, in conjunction with feedback plus feedforward control to facilitate the design of the current loop. A feedback current corrector is used to reduce distortion associated with the input current over a wide load range. The effectiveness of the proposed control method was confirmed with some simulation and experimental results.

A Novel Control to Achieve Optimal Reduction of the E-Cap's Ripple Current for Discontinuous-Conduction Mode Boost PFC Converter

In a power factor correction (PFC) converter, an electrolytic capacitor (E-Cap), which has the advantages of a smaller volume and a low cost compared with other kinds of capacitors at the same voltage rating and capacitance value, is usually used to balance the difference between the pulsating input power and constant output power. However, the E-Cap has a bigger equivalent series resistance and the ripple current flowing through it will produce loss and heat, therefore, shortening its lifetime. So the E-Cap, a component that has the shortest life in a PFC converter, decides the lifetime of the power source. In this paper, the mathematical relationship between the root mean square (RMS) value of the E-Cap's ripple current and the converter's parameters are derived for a DCM boost PFC converter. The corresponding third input current harmonic is figured out for the optimal reduction of the RMS value of the high-frequency ripple current, so that the E-Cap's lifetime can be greatly improved. A method of fitting the duty cycle and the simplified circuit implementation are further proposed. Compared with the traditional control, the proposed minimum RMS value control also achieves an efficiency improvement as the critical inductance is increased and the peak and RMS current value of the power components are, therefore, decreased. The experimental results from a 120-W prototype are given to verify the effectiveness of the analysis.

The Worst Conducted EMI Spectrum of Critical Conduction Mode Boost PFC Converter

The switching frequency of the boost power factor correction (PFC) converter operating in critical conduction mode (CRM) varies in a line cycle, making the conducted electromagnetic interference (EMI) spectra of the converter appear great differences under different input voltage and load conditions. The EMI filter should be designed according to the worst conducted EMI spectrum of the converter, so as to suppress the conducted EMI of the converter to be lower than the standard limits under all working conditions. This paper analyzes the characteristics of the common-mode (CM) and differential-mode (DM) noise spectra of the CRM boost PFC converter, and discusses the effects of the varied switching frequency on the peak, quasi-peak (PK), and average (AV) conducted EMI spectra. It is revealed that, for the conducted EMI limits defined in EN55022 class B, which are specified within 150 kHz to 30 MHz, the EMI filters required for suppressing the QP spectra of the conducted EMI of the CRM boost PFC converter are larger than that for suppressing the AV spectra, and the QP values of the conducted EMI under all working conditions are lower than a certain maximum boundary. The input voltage and load conditions for the worst CM and DM noise spectra of the converter are derived in this paper, thus the repetitive measurements and numerical calculations are avoided. A CRM boost PFC converter prototype is fabricated, and the evaluation of the measured conducted EMI spectra and the EMI filter design example verified the theoretical analysis.

Enhanced Variable On-time Control of Critical Conduction Mode Boost Power Factor Correction Converters

Critical conduction mode boost power factor correction converters operating at the boundary of continuous conduction mode and discontinuous conduction mode have been widely used for power applications lower than 300W. This paper proposes an enhanced variable on-time control method for the critical conduction mode boost PFC converter to improve the total harmonic distortion characteristic. The inductor current, which varies according to the input voltage, is analyzed in detail and the optimal on-time is obtained to minimize the total harmonic distortion with a digital controller using a TMS320F28335. The switch on-time varies according to the input voltage based on the computed optimal on-time. The performance of the proposed control method is verified by a 100W PFC converter. It is shown that the optimized on-time reduces the total harmonic distortion about 52% (from 10.48% to 5.5%) at 220V when compared to the variable on-time control method.

A feedforward compensation design in critical conduction mode boost power factor correction for low-power low totalharmonic distortion

For low-power low total harmonic distortion (THD), based on the CSMC 0.5 μm BCD process, a novel boost power factor correction (PFC) converter in critical conduction mode is discussed and analyzed. Feedforward compensation design is introduced in order to increase the PWM duty cycle and supply more conversion energy near the input voltage zero-crossing points, thus regulating the inductor current of the PFC converter and compensating the system loop gain change with ac line voltage. Both theoretical and practical results reveal that the proposed PFC converter with feedforward compensation cell has better power factor and THD performance, and is suitable for low-power low THD design applications. The experimental THD of the boost PFC converter is 4.5%, the start-up current is 54 μA, the stable operating current is 3.85 mA, the power factor is 0.998 and the efficiency is 95.2%.

Reducing Storage Capacitor of a DCM Boost PFC Converter

The discontinuous current mode boost power factor correction (PFC) converter automatically achieves PFC when the duty cycle is kept constant in a line cycle; however, there is large third harmonic in the input current, and the third harmonic has the initial phase of π in respect of the fundamental component. Therefore, the input power factor is low, and a large storage capacitor is needed. Injecting appropriate third harmonic with initial phase of zero into the input current could reduce the storage capacitor. This paper proposes the variable duty cycle control to inject the required third harmonic into the input current to meet the requirement of IEC 61000-3-2 Class D or Energy Star. A method of fitting the duty cycle is further proposed for simplifying the circuit implementation. The experimental results from a 120-W universal input prototype are given to verify the effectiveness of the proposed method.

Interleaved Critical Current Mode Boost PFC Converter With Coupled Inductor

Interleaved critical current mode (CRM) boost power factor correction (PFC) converter is widely employed recently for its high power density. In order to further reduce the volume and the copper usage of the magnetic components, two-phase interleaved CRM boost PFC converter with a coupled inductor is analyzed in this paper. The coupling effects on the input current, the inductor current, the switching frequency and the flux linkage are analyzed separately. If the self-inductances and the magnetic core are the same for both coupled and noncoupled inductors, the number of winding turns of coupled inductor is fewer than that of the noncoupled inductor, which implies a lower cost. Although the input current ripple increases a little since coupling, a reduction in the total volume of magnetic components, including the electromagnetic interference filter and the coupled inductor, is possible if the coupling coefficient is made reasonable.