Showing papers on "Pulse-frequency modulation published in 2020"

Burst-Mode and Phase-Shift Hybrid Control Method of LLC Converters for Wide Output Range Applications

Abstract: For an LLC converter, it is difficult to realize the wide output range with conventional pulse frequency modulation control because of the limited operating frequency. This paper proposes a new hybrid control method. The proposed strategy combines the burst-mode control and phase-shift control methods for the LLC converter. The burst-mode control can regulate the output voltage from zero to its maximum value, and the phase-shift control can reduce the increased resonant current during burst-on time. By using this method, the wide output voltage range is realized with the low resonant current during burst-on time and zero-voltage switch (ZVS) for all switches. The reliability and efficiency of the converter can be improved accordingly. The burst duty ratio is regulated by the reference output voltage, and the phase-shift angle is derived when realizing ZVS for lagging-leg switches. Moreover, the resonant parameters and the maximum phase-shift angle are optimized under the constraints of current stress and ZVS condition. This method is easy to be implemented in a low-cost microcontroller because high-frequency real-time calculations are not necessary. A 1.5-kW prototype is built to verify the feasibility and validity of the proposed control method.

A Dual-Output Single-Stage Regulating Rectifier With PWM and Dual-Mode PFM Control for Wireless Powering of Biomedical Implants

Abstract: This paper presents a reconfigurable, dual-output, regulating rectifier featuring pulse width modulation (PWM) and dual-mode pulse frequency modulation (PFM) control schemes for single-stage ac-to-dc conversion to provide two independently regulated supply voltages (each in 1.5–3 V) from an input ac voltage. The dual-mode PFM controllers feature event-driven regulation as well as frequency division. The former incorporates stable, fast, digital feedback loops to adaptively adjust the driving frequency of four power transistors, M P 1∼4, based on the desired output power level to perform voltage regulation and deliver fast, transient, load currents. The latter sets the driving frequency of M P 1∼4 to a user-defined fraction (1/1 ∼ 1/32) of the input frequency (1–10 MHz). The PWM controllers incorporate stable, analog, feedback loops to accurately adjust the conduction duration of M P 1∼4 for voltage regulation and can be combined with PFM frequency division for an extended operation dynamic range. Fabricated in 0.18 μm 1P/6M CMOS, the regulating rectifier features power conversion efficiency (PCE) of >83.8% at 2 and 5 MHz, with the first output channel delivering ∼1 mW from VDD of 1.5 V and the second output channel delivering variable power from VDDH of 2.5 V to a load in the range of 0.1 to 1 kΩ. Peak PCE values of 90.75% (2 MHz, 100 Ω) and 90.7% (5 MHz, 200 Ω) are also measured. The regulating rectifier is suitable for the emerging modality of capacitive wireless power transfer to biomedical implants.

Design and Implementation of a LLC Resonant Solid-State Transformer

Abstract: In this study, analysis and control of a highly efficient, high-power full-bridge unidirectional resonant LLC solid-state transformer (SST) are discussed. A combination of pulse frequency modulation and phase-shift modulation is utilized to control this resonant converter for a wide load range. The converter is designed to maintain soft switching by using a resonant circuit to minimize the switching loss of the high-frequency converter. Zero-voltage-switching (ZVS) is achieved for the H-bridge converter. The ZVS boundary for the proposed combined control method is also analyzed in detail. The experimental setup for the suggested configuration was implemented, and the performance of the proposed control scheme and resonant LLC SST have been verified with test results. The proposed combined control scheme improves control performance. The obtained results show that, the proposed system can regulate output voltage and maintain soft switching in a wide range of load. Thus, the efficiency of the system is improved and an efficiency of 97.18% is achieved.

A Three-Level Boost Converter With Full-Range Auto-Capacitor-Compensation Pulse Frequency Modulation

Abstract: A three-level boost converter enables efficient voltage step-up power conversion with high power density by reducing the inductance and blocking voltage requirements in a conventional boost converter. An auto-capacitor-compensation pulse frequency modulation (ACC-PFM) controller, combining peak and valley current-mode controls, is proposed to resolve the issue of unbalanced flying capacitor voltage, as well as to regulate the output voltage. The capacitor balance is further strengthened through a delay-equalized level shifter that generates duty ratios with only sub-nanosecond deviations. The step-up power conversion from the input voltage of 0.3–3.0 V to the output voltage of 2.4–5.0 V is demonstrated through a prototype converter implemented in a 65-nm CMOS process with 0.28 mm2 active area. This converter achieves 96.8% peak efficiency and an 83-mA peak output current, with an 8 $\times $ peak step-up conversion ratio.

Fully-Integrated Reconfigurable Charge Pump With Two-Dimensional Frequency Modulation for Self-Powered Internet-of-Things Applications

Abstract: In this paper, we propose a fully-integrated reconfigurable charge pump in a 0.18- $\mu \text{m}$ CMOS process; this converter is applicable for self-powered Internet-of-Things applications. The proposed charge pump uses a two-dimensional frequency modulation technique, which combines both the pulse-frequency modulation (PFM) and pulse-skip modulation (PSM) techniques. The PFM technique adjusts the operating frequency of the converter according to the variations in the load current, and the PSM technique regulates the output voltage. The proposed two-dimensional frequency modulation technique can improve the overall power conversion efficiency and the response time of the converter under light load conditions. A photovoltaic cell was chosen as the input source of the proposed converter. To adapt to the variations in the output voltage of a photovoltaic cell under different light illumination intensities, we built a reconfigurable converter core with multiple power conversion ratios of 2, 2.5, and 3 for the regulated output voltage of 1.2 V when the input voltage ranged from 0.53 V to 0.7 V. Our measurement results prove that the proposed capacitive power converter could achieve a peak power conversion efficiency of 80.8%, and the efficiency was more than 70% for the load current that ranged from $10~\mu \text{A}$ to $620~\mu \text{A}$ .

High-Efficiency Switched-Capacitor DC-DC Converter with Three Decades of Load Current Range Using Adaptively-Biased PFM

Abstract: A fully-integrated switched-capacitor (SC) DC-DC converter that steps down 2.0 V to 0.9 V with a peak efficiency of 80% is implemented in a 0.18 μ m CMOS process. An ultra-low-power voltage-controlled oscillator that generates a wide range of switching frequencies is proposed to extend battery runtime. An efficiency >70% for load currents in the range of 12 μ A to 17.8 mA is achieved by implementing a novel adaptively-biased pulse frequency modulation (ABPFM) technique in the controller. A symmetric charge-discharge topology with two-phase time interleaving is used as a power stage to reduce the output voltage ripple to <72 mV over the entire load current range.

A Novel APWM Control Scheme for GaN Based Full-Bridge CLLC Resonant Converter with Improved Light-Load Efficiency

Abstract: CLLC resonant converter normally faces light-load problems of unsatisfying voltage regulation and efficiency This paper presents a novel asymmetric pulse width modulation (APWM) control scheme to improve the voltage regulation ability and efficiency of full-bridge CLLC resonant converter In this control scheme, the proposed APWM method is utilized to reach the desired voltage gain lower than unity at resonant frequency with soft switching of all switches in light-load conditions, and the pulse frequency modulation (PFM) is combined to realize the voltage gain higher than unity In comparison with traditional PFM, the proposed control scheme effectively regulates the output voltage and achieves satisfactory efficiency over entire load conditions This control scheme is verified by experiments on a 215V/380V and 200W GaN based full bridge CLLC converter prototype, proving desirable voltage gain and favorable efficiency from light-load to full-load conditions

Stability Analysis of Constant Current Controlled Primary-Side Regulation Flyback Converter

Abstract: In low power applications, primary-side regulation (PSR) flyback converter with discontinuous conduction modulation (DCM) mode is widely used to realize constant output current for its simple structure and low cost. In peak current control method, the output current can be predicted from the primary peak current, the demagnetization time and the switching period. Based on the current prediction, a pulse width modulation (PWM) mode and a pulse frequency modulation (PFM) mode are used. However, as the output current cannot be sampled directly in PSR flyback converter, traditional small-signal modelling method based on the control and output variables cannot be used. And there is no stability analysis for these constant current (CC) controlled PSR flyback converters. In this paper, a discrete matrix analysis method is proposed to analyze the stability of CC controlled PSR flyback converter. An iterative matrix of the control and output variable perturbations is obtained and the stability can be acquired from the eigenvalues. Oscillation occurs in above PWM mode and stable control is realized in PFM mode. An improved PWM mode is thus proposed and analyzed for stable control. The analysis is verified in a PSR flyback converter with 1.92A.

A Digital Sensor-less Synchronous Rectification Algorithm for Symmetrical Bidirectional CLLC Resonant Converters

Abstract: For bidirectional CLLC resonant converters, synchronous rectification (SR) is a key technique that can reduce the conduction losses by replacing the diodes to bring an improvement of the performance Unfortunately, existing methods suffer from high cost, complex hardware and imprecise control effect Aiming at these problems, this paper proposes a digital sensor-less SR algorithm based on time domain model for symmetrical CLLC converters under pulse frequency modulation (PFM) The developed approach can enable the SR switching action more precisely within almost full load range without any additional hardware, eg, anti-parallel diode, SR IC and high bandwidth sensor Its implementation only needs to measure the DC signal (ie, the output current), rather than to sense the zero-crossing point of the high frequency resonant current Additionally, a simplification of the algorithm has been made with no accuracy compromise, thus the requirements of the digital controller decrease greatly Finally, experiments have been performed on a prototype to verify the validity and applicability of the presented SR algorithm, and the experimental results show that the SR effects are substantially improved

Control Strategies Overview for LLC Resonant Converter with Fixed Frequency Operation

Abstract: For the LLC resonant converter, pulse frequency modulation (PFM) is the most frequently used control strategy. However, for wide input or output operation range, a wide switching frequency range is required, which causes efficiency loss. Therefore, some fixed frequency control strategies are proposed for the LLC resonant converter, including phase shift modulation (PSM), pulse width modulation (PWN), and resonant frequency modulation (RFM). In this paper, a comprehensive comparisons of different control strategies are implemented. The operational principles and system control diagram for each control strategy are discussed. Then, comparisons among different fixed switching frequency control strategies are presented. Finally, the VIC LLC is selected as an example to demonstrate its operation and effectiveness.

A Comprehensive Overview in Control Algorithms for High Switching-Frequency LLC Resonant Converter

Abstract: An LLC resonant converter has been widely used in various industrial applications because of its high cost-effectiveness, high power conversion efficiency, simple design methodology, and simple control algorithms using a pulse frequency modulation (PFM). In addition, the soft switching capability of the LLC resonant converter is good to obtain high switching frequency operations, which can get the high-power density of the power converter. Over the past years, several studies have been conducted to improve the performance of a high switching frequency LLC resonant converter with resonant tank design, optimal power stage design, and enhanced control algorithms. This paper is the review paper in terms of the control algorithms for the LLC resonant converter. It focuses on the overview of the high switching-frequency LLC resonant converter in terms of the control algorithms. The advanced control algorithm can improve power conversion efficiency, dynamic performance, tight output voltage regulation, and small electro-magnetic interference. The operational principles of the control algorithms are briefly explained to show their own characteristics and advantages. Thereafter, the research issues for the future works will be discussed in the conclusion.

Dynamic Characteristics of Zero-Current-Switching Quasi-Resonant Buck Converter under Variation of Resonant Circuit and Load Parameters

Abstract: The investigation of resonant circuit parameters influence on dynamic characteristics and electromagnetic processes in half-wave quasi-resonant buck converter is presented. The dependences of transistor non-zero conductivity duration, transistor switching-off current value, transistor voltage and current peak values under variation of resonant inductance and resonant capacitance are obtained by dint of simulation. The dependences of these characteristics and output voltage under variation of active and reactive part of load impedance are also received. All above allow simplifying construction of robust table-based control system for similar converters.

A Power Factor Corrected Resonant EV Charger Using Reduced Sensor Based Bridgeless Boost PFC Converter

Abstract: A reduced sensor based bridgeless boost (BLB) PFC converter fed full bridge inductor-inductor capacitor (FBLLC) converter for electric vehicle (EV) charging, is presented in this work This converter is a twin stage converter, where the first stage is a PFC-BLB converter operating in continuous inductor conduction mode (CICM), and the second stage is a 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 pulse width modulated (PWM) control, whereas FBLLC converter employs a pulse frequency modulation (PFM) 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 TMS 320F 28035 digital signal processor (DSP) to charge an EV battery with a maximum power of 2 7kW and a current of 50A

Fast Maximum Power Point Tracking Technique With 4-Bits/Cycle SAR ADC For Photovoltaic Energy Harvesting System

Abstract: This paper presents a photovoltaic(PV) energy-harvesting system with fast maximum power point tracking (FMPPT) circuit that utilizes 4-bit successive approximation register analog to digital converter (SAR ADC) suitable for solar cells. Solar Panel’s output power depends on switch duty ratio of inductive-boost DC/DC converter. Usability of 4-bit/cycle SAR ADC to adjust duty ratio is proved through the measurement, using conventional Pulse Frequency Modulation (PFM) boost converter. This circuit achieves short tracking time of 4-cycle in order to reach the MPP and high MPPT efficiency of 99.5 %, while consuming the low power. The switches and control stages were implemented into 0.18 -um CMOS process, and a chip size is 2.13 x 1.66 mm2.

An Electric Vehicle Charger Based on Vienna Rectifier and Resonant LLC Converter

Abstract: In this work, a medium and high power rating electric vehicle (EV) charger based on Vienna rectifier (VR) and half bridge resonant inductor-inductor-capacitor (LLC) converter, is presented The two switch VR forms the front-end converter, and performs active power factor correction (PFC), by operating under continuous conduction mode (CCM) Moreover, its output voltage is regulated by an outer voltage control loop, in a two loop pulse width modulated (PWM) control The EV battery is charged using constant voltage (CV) and constant current (CC) controller by a pulse frequency modulation (PFM) based half bridge LLC converter The DC-DC conversion stage of this charger is soft switched due to zero voltage switching in LLC converter Simulation results and its performance under steady state and dynamic conditions, are presented Moreover, the power quality (PQ) and steady state results are verified and presented for a 56kW experimental prototype

An Asynchronous Boost Converter With Time-Based Dual-Mode Control for Wide Load Range and High Efficiency in SSD Applications

Abstract: A highly integrated, high-voltage dual-mode boost converter is presented for solid-state drives applications in portable devices, where standby mode efficiency with 100-mA load. To enhance efficiency in light load conditions and to achieve a wide operation load range, loss minimization by balancing conduction and switching losses is adopted, and a dynamic power-gating scheme is applied for pulse frequency modulation mode operation. Moreover, robust dual-mode operation is implemented with a time-based control scheme, which enables operation with a lower peak current for optimal loss balancing. The proposed converter is fabricated in 130-nm complementary metal-oxide-semiconductor process with an area of 1.7 mm2. The measured efficiency for supplying 12-V output from 5.5-V input is 91% at its peak load of 40 mA and 85% with an extremely light load of 200 μA. It also achieves a wide dynamic load range from 200 μA to 600 mA for >85% efficiency and from 2 to 150 mA for >90% efficiency.

Analysis and design of LLC resonant converter with variable magnetising inductance control

Abstract: A conventional pulse frequency modulation (PFM) controlled LLC resonant converter requires a wide switching frequency operating range to regulate the output voltage. There are some disadvantages of PFM LLC resonant converters: (i) the design and optimisation of magnetic components and gate driver circuitry are challenging; (ii) due to the variable switching frequency operating range, electro-magnetic interference performance of the converter is degraded; (iii) efficiency degradation; (iv) inability to achieve independent control in multiple-output applications. To address the above-mentioned problems and achieve fixed switching frequency operation, a variable magnetising inductance control (VMIC) strategy is proposed. In the proposed VMIC control strategy, the operating switching frequency of the primary switch is fixed and the duty cycle remains constant at 0.5. At the resonant frequency operating point, the output voltage is independent of both the magnetising inductance and load. In addition, the zero current turn-off operation of the secondary rectifier requires that the switching frequency be designed below the resonant frequency. The operational principles and design considerations of the LLC resonant converter with VMIC are presented. Experimental results from a 200 W prototype are presented to validate the theoretical analysis and the effectiveness of the proposed VMIC control strategy.

Zero-Vector-Injection Based Current Sharing Control of Interleaved Full-Bridge LLC Resonant Converters

Abstract: Interleaved LLC resonant converters are widely used in various fields. However, interleaved LLC converters under Pulse Frequency Modulation (PFM) will lose the regulation of individual phases, causing a load sharing problem. Existing load sharing solutions have limitations; for example, phase shedding and current sharing cannot be realized at the same time. This paper proposed a novel current sharing method for interleaved full-bridge LLC resonant converters. Based on Zero-Vector-Injection, the voltage applied to the resonant tank is controlled to compensate for the difference in gain caused by component tolerance. The modulation strategy is proposed to maintain soft switching after Zero-Vector-Injection, and the phase shedding technique is also used to improve the efficiency at a light load. The detailed theoretical analysis and implementation method are proposed and validated using simulations. Experiments are also carried out to verify the feasibility of the proposed strategy based on a 2-phase 1.8 kW prototype.

An Input-Series Output-Independent Full-Bridge Dual Active Bridge Converter with Soft-Switching Characteristics for Charging and Balancing Electric Vehicle Battery Stacks

Abstract: In this paper a multifunctional configuration for charging and balancing a battery stack, using modular converter design approach is proposed. Battery stacks consist of multiple cells to reach the desire voltage level and are conventionally charged altogether. The author proposes that the battery stack is divided into Battery Groups (BGs) that can be independently charged, controllably discharged under load and also balanced. The equations that describe the converter reference current for any state of operation and also permit minimization of the required sensors in the system, are presented. Mathematical modeling and detailed characteristic curves are derived based on the charging profile of the selected battery. The proposed control method relies on Pulse Frequency Modulation (PFM) and Phase Shift Modulation (PSM) to maintain Zero Voltage Switching (ZVS) and accomplish the desired output. The main advantages are the soft-switching characteristics, the flexibility in variable voltage and power levels due to modular design, and the online equalization of the batteries during charging and discharging.

Batteryless DC-DC Boost Converter for Thermoelectric Energy Harvesting Devices

Abstract: A batteryless DC-DC boost converter with low startup voltage for thermoelectric energy harvesting applications is implemented in a TSMC 018µm CMOS process A LC oscillator enables the converter to operate from a 200-m V input voltage A high duty cycle controls the switching frequency of the pulse frequency modulation (PFM) boost converter to lower its switching loss, with output voltage regulated at 11V and peak efficiency of 63%

A Model of Continuous-Time Sigma Delta Modulation Based on Pulse Frequency Encoding

Abstract: The parallelism between a first-order sigma-delta modulator and a VCO-based ADC allows to calculate the DFT of the sigma delta sequence using Pulse Frequency Modulation theory. This paper exploits this parallelism to propose a more general model that links continuous time sigma delta modulators of an arbitrary order with Pulse Frequency Modulators. This novel point of view also predicts the spectral contents of a sigma delta encoded sequence beyond the white quantization noise model. The quantization noise can be split in two components, a deterministic one representing the carrier harmonic sidebands of a Pulse Frequency Encoded signal and a noise shaped pseudorandom signal representing the sampling operation. We seize these findings to propose a conjecture on the stability of a sigma delta modulator.

Quick implementation of Pule Wise Modulation(PWM), Pulse Frequency Modulation(PFM) and mixed PWM/PFM on FPGA chip

Abstract: This paper proposes a method to successfully embedded three control waveforms, PWM (Pulse Width Modulation), PFM (Pulse Frequency Modulation), and PWM-PFM (pulse width frequency modulation), into an FPGA (Field-Programmable Gate Array) chip. The three types of control modulation are generally used in power supply design. A single function IC with PWM or PFM is already on the market. However, there is no such chip on the market to integrate these three control modulation functions into one IC chip. An HDL (Hardware Description Language) algorithm that can satisfy the above three functions at the same time is proposed and implemented in the FPGA chip. We also proposed several experimental measurements to prove that these three functions do coexist in the FPGA chip.

LLC-MMC Resonant DC-DC Converter: Modulation Method and Capacitor Voltage Balance Control Strategy

Abstract: DC-DC converter plays an important role in high-voltage direct-current (HVDC) transmission and medium-voltage DC (MVDC) distribution system Dual-active bridge topology with modular multilevel converter (DAB-MMC) is a preferred choice due to the small transformer size and high voltage handling ability However, DAB-MMC cannot achieve soft-switching over entire load conditions Meanwhile, the traditional LLC resonant converter, which is widely used for low voltage application, features inherent ZVS soft-switching because of the resonant network Combine the DAB-MMC and traditional LLC resonant converter, this paper proposes a LLC resonant converter with MMC structure (LLC-MMC) The pulse frequency modulation (PFM) method with quasi-square-wave is utilized to achieve low dv/dt stress Besides, capacitor voltage balance control strategy executed in dead time is proposed to maintain the balance LLC-MMC guarantees full ZVS soft-switching over a wide load resistance range Finally, the proposed modulation method and balance strategy are verified by the sufficient simulation and experimental results

Low Power Design Techniques for Integrated Circuits

Abstract: It is essential to retain power and energy efficiency in low-power integrated circuits (ICs) over a wide load current/voltage range to reduce the consumption from the battery in portable/non-portable devices. The power/energy efficiency highly depends on voltage and frequency scaling when all the parts of the devices are in operation. There are also power and clock gating when all the parts of the devices are not in operation. The dynamic and static voltage scaling are main part for power gating. The power saving can be done by varying the supply voltage to ICs. The pulse width, pulse skip, depth and frequency modulation are common techniques for clock gating/frequency generation. The pulse width modulation (PWM) is generally used for fixed frequency operation. The pulse frequency modulation (PFM) is generally used for variable frequency operation depending on load voltage and current demands. The pulse skip modulation (PSM) is special technique to skip the pulses for frequency operation depending on IC operation mode (sleep mode and standby mode). In this chapter, all the existing techniques available for power reduction are discussed with the suitable diagram and examples.

Pulse frequency modulation control of a power converter

Abstract: A power converter such as e.g. a buck converter operated in pulse frequency modulation PFM mode and a method are presented. The power converter has an inductor, a switching element, threshold current generator, resistive element, threshold current comparator, a current sensing means, and a current injecting means. The switching element controls an inductor current flowing through the inductor. The threshold current generator generates a threshold current based on a comparison between a reference voltage and an output voltage. The resistive element generates a threshold voltage at a reference node. The threshold current comparator generates, by comparing said threshold voltage with an inductor voltage, a control signal for turning off or on the switching element. The current sensing means senses a current indicative of the inductor current. The current injecting means generates an injection current based on the current sensed by the sensing means.

A Sliding Mode Control Strategy with Discrete Pulse Frequency Modulation for CLLC DC-DC Converter

Abstract: A sliding mode control (SMC) strategy with discrete pulse frequency modulation is applied for CLLC resonant converter and the sliding surface is designed to be easy to realize by hardware circuit. The method of input-output linearization is introduced to design SMC controller to guarantee the robustness and improve the dynamic performances. The theoretical analysis and the dynamic performances are verified by the simulation. The simulation results show that the control strategy has a strong robustness and a quick dynamic response. And the chattering caused by SMC controller is small.

Бифуркационные явления в преобразователе напряжения c частотно-импульсным управлением для ветрогенераторной установки

Abstract: The relevance of the paper is determined by the need to improve energy efficiency parameters of power converting devices for the needs of alternative energy, in particular for a wind generator. One of the difficulties of converting wind energy is the low level of energy efficiency of this process. Due to the variable value of the rotational speed of the blades of the wind turbine in a certain time interval, the parameters of the received energy are variable, therefore, the settings of the secondary converters of electric energy must correspond to the time intervals for generating the signal. Improving the functioning of alternative power sources is possible through the use of multi-frequency stabilization modes of the converter. The article considers a model of a pulse-modulation step-down voltage converter based on pulse‑frequency modulation. The authors have studied and proposed the methods for changing the width of the working zone of a single-frequency stabilization mode. The main aim of the study is to analyze the changing modes of the secondary voltage converter of a wind generator and to develop approaches to the study of bifurcation phenomena that occur in a converter with pulse‑frequency modulation by constructing a mathematical model and numerically-analytical modeling of a buck voltage converter to improve the reliability of the system under consideration. Methods: study of literature on standard energy conversion schemes in wind turbines with an intermediate DC link; mathematical modeling and conducting numerical experiments to change the operational parameters of a buck converter with pulse‑frequency modulation to identify bifurcation in it; construction of bifurcation diagrams for various parameters of the transducer in order to increase the reliability of operation. The results. The authors obtained the mathematical models and numerical-analytical technique for constructing and identifying dynamic modes of a voltage converter with pulse‑frequency modulation acting as a DC link of a wind generator set and constructed the bifurcation diagrams for voltage stabilization at different parameters of the control system. The simultaneous presence of single-frequency and burst-packed modes was shown, bifurcation of period division was identified; the influence of the system parameters on the operating modes was studied, and methods for changing the width of the working zone of the single-frequency stabilization mode were proposed.

Zero-current switching with LC resonant tank circuit and capacitor isolation DC-DC converter

Abstract: Insulated DC-DC switching power supplies have been using a magnetic coupling method using a transformer for several decades. Transformers have excellent properties as a material that can change the voltage while insulating. On the other hand, it can be considered that there is a limit to the reduction in size and weight with increasing switching frequency. Therefore, we are interested in the insulation type converter by the capacitor coupling. The principle of the capacitor insulation method was introduced in 1994, but it was pointed out that the problem of noise that occurs when the power device is turned on and off. After that, a case where noise was suppressed by using a series resonant circuit of a capacitor and an inductor was reported. However, it had no means to control the output voltage, and had the problem that fluctuations in the input voltage would directly cause fluctuations in the output. Therefore, we maintain “resonance state” by providing “two sets of LC resonance tank circuits corresponding to the resonance frequency” and changing the operating frequency for ON width pulse of fixed width (pulse frequency modulation or pulse density modulation). We propose that the output voltage can be controlled while. The voltage control characteristics are analyzed using Spice Simulation, and the Co-relation with the experimental value is confirmed. By using frequency/density modulation, the inverter is always switched at the current zero crossing point, enabling Noiseless switching. Regarding the possibility, we will analyze the switching characteristics due to the deviation from the resonance point by using ADS; Electronic Design Automation tool, for the noise that may occur in the actual PCB (circuit pattern), and show the results.

Power converter with multi-mode timing control

Abstract: A converter circuit includes a power stage circuit configured to convert an input voltage to an output voltage provided at an output, and a control circuit configured to control the power stage circuit. The control circuit is configured to operate in one of a pulse frequency modulation (“PFM”) mode and a pulse width modulation (“PWM”) mode depending on a current supplied to the output. The control circuit includes a multi-mode timer circuit configured to provide a switching signal to set an off time for each switching cycle of the power stage circuit during the PFM mode and during the PWM mode.