Boost Mode Research Articles

An In-Depth Investigation of a Z-Source Ultrasparse Matrix Converter in Buck and Boost Modes of Operation

Z-source networks are recently being employed to enhance the boosting capability of matrix converters. This paper concentrates on cascaded Z-source ultrasparse matrix converter (ZSUSMC), where the Z-source network is placed between the three-switch input rectifier stage and the six-switch output inverter stage. Two space vector modulation schemes, with and without a zero state in the rectifier stage modulation, are presented and their advantages and disadvantages are discussed. In addition, restrictions imposed on the converter operation in buck mode, which arise from unidirectional nature of the ultrasparse matrix converter, are discussed and a solution is proposed for offsetting those limitations. Furthermore, an optimal switching pattern, which results in minimum possible number of changes in the switching states as well as even distribution of the shoot-through state over the entire control period, is proposed. Also, common-mode voltages of the converter in all possible switching configurations are calculated. Hardware-in-the-loop studies of a ZSUSMC-based permanent magnet synchronous motor drive are carried out to evaluate the performance of the drive under the proposed modulation techniques. The obtained results are compared with a recent study and the superiority of the proposed method in terms of converter input/output current quality is demonstrated.

Influence of output conductance on characteristic frequencies of switch mode BUCK and BOOST converter

Abstract Characteristic frequencies corresponding to poles and zeros of small-signal control-to-output transfer functions of popular DC-DC converters (BUCK and BOOST) are analyzed. The main attention is paid to influence of load conductance on the characteristic frequencies for converters working in continuous conduction mode (CCM) as well as in discontinuous conduction mode (DCM). Parasitic resistances of all converter components are included in calculations. In addition the improved description of CCM-DCM boundary is presented. The calculations are verified experimentally and good consistency of the results is observed.

High Ratio Bidirectional DC-DC Converter with a Synchronous Rectification H-Bridge for Hybrid Energy Sources Electric Vehicles

In order to match the voltages between high voltage battery stacks and low voltage super-capacitors with a high conversion efficiency in hybrid energy sources electric vehicles (HESEVs), a high ratio bidirectional DC-DC converter with a synchronous rectification H-Bridge is proposed in this paper. The principles of high ratio step down and step-up operations are analyzed. In terms of the bidirectional characteristic of the H-Bridge, the bidirectional synchronous rectification (SR) operation is presented without any extra hardware. Then the SR power switches can achieve zero voltage switching (ZVS) turn-on and turn-off during dead time, and the power conversion efficiency is improved compared to that of the diode rectification (DR) operation, as well as the utilization of power switches. Experimental results show that the proposed converter can operate bidirectionally in the wide ratio range of 3~10, when the low voltage continuously varies between 15V and 50V. The maximum efficiencies are 94.1% in the Buck mode, and 93.6% in the Boost mode. In addition, the corresponding largest efficiency variations between SR and DR operations are 4.8% and 3.4%. This converter is suitable for use as a power interface between the battery stacks and super-capacitors in HESEVs.

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.

Scalar and fermion representations of the Lorentz group in Minkowski plane, QFT correlators, pair creation in electric field and the Unruh effect

Boost modes [Formula: see text] are eigenfunctions of the Lorentz transformations generator in two-dimensional (2D) Minkowski space (MS). We demonstrate and discuss deep interrelation between the boost modes and the field correlators, also known as Wightman functions. In the case of a massive scalar field, the boost modes, as functions of the spectral parameter [Formula: see text], contain the Dirac delta-function singularity [Formula: see text] at the light cone. The zero boost mode coincides up to a constant factor with the Wightman function. The light cone singularity of boost modes for a fermion field is stronger. For this case, they contain the Gelfand [Formula: see text]-function of complex argument [Formula: see text], while the Wightman function components coincide with analytical continuation of the boost modes set towards the spectral values [Formula: see text]. We argue that due to the discovered properties of the boost modes the so-called Unruh modes, which are at the core of the Unruh effect derivation, do not constitute a complete set in MS and thus cannot be used for quantization of neither scalar, nor fermion field. Finally, we discuss boost modes for the case of the constant electric background and rederive the well-known result for spontaneous pair creation rate. Solution of this problem in the boost modes representation reveals distinctions between the Unruh problem and the effect of pair creation by an electric field in vacuum.

Analysis of Non-minimum Phase in Buck-Boost Converter

In this paper, relations among the parameters of the non-minimum phase for the Buck-Boost converter are studied. It is demonstrated that when the Buck-Boost converter works in Buck mode, the negative regulation voltage is determined by the converter with the pre-designed inductor and load as the duty ratio D D >0.382, and the duty ratio has a limited effect on the negative regulation voltage of the converter; when the Buck-Boost converter works in Boost mode，the negative regulation voltage is determined jointly by the converter with its pre-designed inductor, load and duty cycle, for which performs that the higher the output voltage is (i.e., the greater the duty ratio is)，the more severe undershoot of the voltage will be. The conclusion of this paper has a guidance meaning for decreasing the negative regulation voltage of the Buck-Boost converter. Finally the correctness of the analysis for the non-minimum phase is verified by simulations and experiments.

English

A discharging (Boost) mode of the bidirectional dc-dc converter with fuzzy logic controller is present in this paper .To achieve high voltage step-up conversion two boost conversion stages are obtained by controlling one power switch. High efficiency is achieved since the energy stored in the leakage inductor is recycled. For understanding the advantages of fuzzy logic control conventional PI control has applied and compared under the same circumstances of the converter. Simulation results show that fuzzy controlled converter has an improved steady state and transient performance than PI controlled converter. This converter can be used for Board Mounted Power supply (BMPS).

A Digitally Controlled Critical Mode Boost Power Factor Corrector With Optimized Additional On Time and Reduced Circulating Losses

In many low-to-mid power applications, critical mode boost power factor corrector converters are widely used because of its low switching loss and simple control. However, near the zero crossing of the input line voltage, an input current distortion and a low power factor are caused by delayed switching period and negative input currents. Generally, an additional on-time method according to the input voltage is used to compensate the input current distortion. However, a detailed quantitative analysis for the exact additional on time has not been studied till now. In this paper, the explicit form of the optimized additional on time has been obtained using a quantitative analysis and the advantage of the digital control. From a state trajectory and “net input charge” analysis, it is shown that the optimized on time should be related to not only the input voltage, but also the output power. Also, in order to improve the efficiency in a high input and light load condition, circulating currents are reduced in the inevitable dead angle with a gate turning-off technique. By using digital control, the optimized additional on time and the gate turn-off technique have been implemented with the 90–230 Vrms input and 380 V/200 W output prototype.

Boost modes for a massive fermion field and the Unruh problem

We show that the Wightman function of a free quantum field generates any complete set of solutions of the relativistic wave equations. Using this approach, we construct the complete set of solutions of the two-dimensional Dirac equation consisting of eigenfunctions of the generator of Lorentz rotations (boost operator). We show that at the surface of the light cone, the boost modes for a fermion field contain the Gelfand delta function of a complex argument. Because of the presence of such a singularity, excluding even a single mode with an arbitrary value of the boost quantum number makes the set of boost modes incomplete. This results in the nonapplicability of the Unruh quantization scheme to a massive fermion field in the two-dimensional Minkowski space-time. Hence, in full accordance with the boson case, the Unruh procedure for a fermion field cannot be used to prove the existence of the Unruh effect.

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 New Buck/Boost Bidirectional DC/DC Converter Base on Soft Change Current Network

There is a problem about high current and voltage spikes in Buck and Boost converters,it will damage main power devices .Therefore, a novel Buck/Boost bidirectional DC/DC converter based on soft change current (SCC) network was given, and Buck and Boost modes ware particularly analyzed.Groups parameters of L/C/D are selected and simulated with Saber software. The optimal combination of L/C/D was ascertainned by observing groups switch waveforms. Theoretical analysis and simulation results show that the voltage and current spike of the power switches is deeply descreased by SCC network.

A Fully ZVS Critical Conduction Mode Boost PFC

Boost converter operating in critical conduction mode is widely used in low-power power factor corrector because of its simplicity and low switching losses. The switching loss due to parasitic capacitor discharge at the on-time instant can also be reduced by a valley switching technique. In this paper, we introduce a new driver topology for the high-side switch in a synchronous boost converter operating in the critical conduction mode to obtain full zero-voltage switching. Using the proposed high-side driver topology, the conventional control circuit is sufficient to control the low-side switch, and no additional control circuit is required to adjust the timing of the switches. Finally, the line current distortion is reduced through the use of on-time extension technique to less than 10% in the defined load range. Based on approximate mathematical calculations, two separate distortion reduction circuits are designed to implement the on-time extension technique for both voltage-mode and current-mode control methods.

An Analysis Method of Operation State for Boost Converter with Voltage Feedback Control

Abstract When system parameters were adjusted, some instability phenomenon could occur in closed-loop DC-DC converter. For improving the stability of converter system, an analysis method of operation state for converter was presented based on the discrete model of continuous conduction mode(CCM) Boost converter with voltage feedback control. This method can avoid fussy derivative operation. The steady equation of CCM Boost converter was deduced and the system parameters condition on which closed-loop instability phenomenon would occur were analyzed, the condition is appropriate to high frequency Boost converter. Corresponding simulation results were given in this paper.

Solid-Duty-Control Technique for Alleviating the Right-Half-Plane Zero Effect in Continuous Conduction Mode Boost Converters

This paper proposes a solid-duty-control (SDC) technique for application in boost converters to maintain a constant duty value and reduce dip voltage during load transient periods. Fast transient response was also achieved because of the variable transient enhancement controller. The proposed SDC technique can provide a stable and regulated output for edge-lit light-emitting diode backlight systems. This converter was used in a 0.25-μm CMOS process. Experimental results show that compared with a conventional design without a fast transient technique, the proposed approach yields about 30% and 80% improvement in undershoot voltage and recovery time, respectively, as load current changes from 50 to 250 mA.

Transient Improvement by Window Transient Enhancement and Overshoot Suppression Techniques in Current Mode Boost Converter

In this paper, a current mode boost converter using window transient enhancement (WTE) and overshoot suppression (OSS) technique is presented for digital still camera (DSC) applications. The peak-to-peak transient overshoot voltage demand of a DSC motor driver is generally within 4%-5% of the regulated value. However, conventional boost converters usually fail to pass this criterion during large load transient. The OSS technique reduces the overshoot voltage when load current changes from heavy to very light. Experimental results show that compared with the use of a conventional current mode boost converter, the use of the technique reduces drop voltage about 62% and overshoot voltage about 51% when the load current has a load step of 400 mA. Moreover, the settling time improves to 43%, which is better than in the conventional case of a 400 mA load current step. The overhead of the silicon area is about 4.5% to achieve the overshoot reduction. The estimated high performance demonstrates that it is suitable for DSC applications.

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.

Control Strategy for Discontinuous Conduction Mode Boost Rectifier with Low Total Harmonic Distortion and Improved Dynamic Response

Due to its simplicity, the discontinuous conduction mode boost rectifier is potentially the least expensive active line-harmonics reducing circuit. Problem statement: The line current however, shows considerable distortion when the peak input voltage is close to the output voltage, As a result, the input power factor is poor. This study proposes a simple, low-cost method to reduce the line harmonics. Approach: A periodic voltage signal was injected in the control circuit to vary the duty cycle of the boost switch within a line cycle so that the third-order harmonic of the input current is reduced and the THD is improved. The proposed technique eliminates the additional harmonic generator, phase detecting and phase-locking circuits, which was proposed in the literature. Instead we can utilize the bridge rectifier's output voltage of the boost converter to modulate the duty cycle of the boost switch. As a result, the injected signal is naturally synchronized with line current. In addition, to obtain nearly constant harmonic content over a wide range of load variation, a modulation index m is used to update the injected signal with a fraction of duty cycle which reflects the load changes. Results: The results proved that third-order harmonic, which was the Lowest Order Harmonic (LOH), can be attenuated by adjusting the modulation index of the injected signal. Moreover, the rectifier shows a good transient performance where the converter's output voltage overshoots during load and input voltage transients is reduced. Conclusions/Recommendations: The proposed circuit can be used as a front-end converter for DC/DC or DC/AC converters in order to improve the power factor of the input current. Also the proposed control circuit could be integrated in a single chip in order to reduce the cost of the industrial implementation.

Mathematical model for split-capacitor push–pull parallel resonant converter in Buck mode

A technique is described whereby a split-capacitor push–pull parallel resonant converter (SC-PPRC) can be operated at a variable switching frequency with zero-voltage switching to provide either a lower (Buck) or higher (Boost) peak variable output voltage than that which would result in the conventional Normal mode. A comprehensive analysis of the SC-PPRC in the Buck mode is yet to be reported. All three modes of operation of the converter are detailed and a mathematical model is presented through which the performance of the converter during the Buck mode can be accurately predicted. The proposed Buck mode is facilitated by operating the converter essentially at a higher switching frequency than in the Normal mode. The higher switching frequency is generated by incorporating a negative and variable time delay into the switching period of the Normal mode. In contrast to both Normal and Boost modes, analysis of the converter in the Buck mode is different and complicated by the formation of two different resonant circuits during each switching cycle. The proposed mathematical solution for the Buck mode is accurate as validated by both simulations and measured results of a 150 W prototype Buck-operated SC-PPRC unit.

Mechanism of period-doubling bifurcation in DCM DC-DC converter

The period-doubling bifurcation in DC-DC converters has been investigated widely. However, the studies main focus on the models of bifurcations and the identification of strange attractors, the essential mechanism causing period-doubling bifurcation was not analyzed. This paper deduces mathematically the conditions of producing the period-doubling bifurcation in discontinuous current mode (DCM) Boost and Buck converters based on voltage feedback control. It exposes the mechanism of the period-doubling bifurcation in DC-DC converters and perfects the theoretical analysis method, puting forward an analytic method for studying the period-doubling bifurcation.