Input Voltage Of Converter Research Articles

Voltage Control for Enhanced Power Electronic Efficiency in Series Hybrid Electric Vehicles

The paper presents a dc-link voltage control scheme by which the power losses associated with the power electronic converters of a series hybrid electric vehicle (HEV) powertrain are reduced substantially. A dc-link commonly connects the three powertrain branches associated with series HEVs, presently interfaced by a three-phase rectifier, a three-phase inverter, and a dual-active bridge (DAB) dc–dc converter. Dynamic efficiency models of the converters are developed, and a methodology is proposed by which the dc-link voltage is varied with respect to its default value, based on the ratio between the battery and dc-link voltages. The voltage control scheme introduced varies the phase shift between the gating signals of the two DAB converter bridges, proportionally to the ratio of converter input voltage to output voltage referred to the transformer primary. This level of instantaneous control forces the converter to operate in boost mode when the battery charges and buck mode when the battery discharges, allowing the converter to persistently avoid hard switching losses over its entire operating range. The control scheme is tested in simulations with a full HEV model by comparing its performance with constant voltage and unity voltage conversion ratio PI control schemes. The scheme proves most effective for vehicles with high hybridization factor driving in an urban environment.

Multichannel LED Driver With <italic>CLL</italic> Resonant Converter

This paper presents a two-stage multichannel light-emitting diode (LED) driver, which contains a buck converter as the first stage and a multichannel constant current CLL resonant converter as the second stage. The forward current of one LED string is sensed for feedback control to regulate the bus voltage, which is the input voltage of the CLL resonant converter. Meanwhile, the currents of other strings are cross regulated. In contrast, the CLL converter is always working at the series resonant frequency to maintain high efficiency. Therefore, this two-stage LED driver could achieve high efficiency over a wide load range. Furthermore, lower dimming is easy to obtain with the regulation of the first stage. Good current balance is achieved with large magnetizing inductance, even if the loads are severely unbalanced. In addition, since the transformer's turns ratio is 1:3, the charging and discharging process of the junction capacitors of secondary-side rectifiers significantly influences the similar process of the output capacitors of primary-side switches during dead time. Meanwhile, the displacement current flowing through the transformer's interwinding capacitor impacts on the current balance among multiple LED strings. With these considerations, a two-stage LED driver prototype is built to verify its good current balance and high efficiency.

Hyper‐plane sliding mode control of the DC–DC buck/boost converter in continuous and discontinuous conduction modes of operation

In this study, a new proportional–integral-type hyper-plane sliding mode controller has been designed for output voltage control of the DC–DC buck/boost converter for its continuous and discontinuous conduction modes of operating conditions. The proposed controller is robust and stable against parameters uncertainties, load disturbance and variations of the converter input voltage. In addition, it is capable of cancelling the non-minimum phase nature effect of the converter so that the designed controller does not need to know the inductor reference current. Moreover, the coefficients of the controller have been designed so that the steady-state error of the converter asymptotically converges to zero. The controller is designed based on fixed-frequency equivalent control approach. Using MATLAB/SIMULINK toolbox and digital signal processor (TMS320F2810) from Texas Instruments, some simulation and practical results are presented to verify the capability and effectiveness of the proposed control approach.

Single-Source Multi-Battery Solar Charger: Analysis and Stability Issues

In this paper, dynamic analysis of a multi-battery dual mode charger, powered by a single solar array and suitable for lead-acid and lithium-ion cell-based batteries is presented. Each battery is interfaced to the solar array by means of a current-controlled buck power stage, operating either in constant power or constant voltage mode. Operation in former/latter charging mode implies regulating input/output voltage of the converter, which is a non-trivial situation since while feeding different batteries, all the converters share the same input terminals, connected to the solar array. It is revealed that when at least one of the batteries operates in constant power charging mode, open-loop instability occurs whenever converter input voltage is lower than maximum power point voltage of the solar array. Consequently, input voltage regulating controller must be designed to stabilize closed-loop dynamics for the worst case of instability, which is also derived. Moreover, it is shown that the dynamics of the converters operating under output voltage control are perceived as disturbances by input voltage control loop and must be properly rejected. Simple loop shaping design is proposed based on a PI controller, allowing stabilizing the system in case of worst case instability and rejecting output voltage control induced disturbances at the expense of non-constant, operating-point dependent closed-loop damping.

Self-Powered 30 µW to 10 mW Piezoelectric Energy Harvesting System With 9.09 ms/V Maximum Power Point Tracking Time

A piezoelectric (PE) energy harvesting system with one-cycle maximum power point (MPP) sensing is presented. The one-cycle MPP sensing method uses a very small size sensing capacitor and it can make the transducer output voltage reach the open circuit voltage within one cycle. The proposed MPP sensing block can sense the open circuit voltage with a proposed peak detector and stores the MPP voltage using charge sharing blocks. The one-cycle MPP sensing approach simplifies the design of an MPP tracking algorithm and greatly reduces the tracking time. All control blocks are self-biased and choose the higher voltage between the input or output voltages of the switching converter as a supply voltage (V $_{DD}$ ). Therefore, a voltage multiplexer and a low-power ramp generator with V $_{DD}$ independence are also proposed to control the system without additional DC to DC converter. The entire system has been implemented in a 0.35 µm BCDMOS process. It operates at 90 kHz with a 10-mH inductor. The total power dissipation of the controller is 10 µW at a V $_{DD}$ of 2.7 V. The MPP tracking time is only 9.09 ms/V when the input voltage of the switching converter is changed from 3.4 V to 1.2 V.

Dynamics of Photovoltaic-Generator-Interfacing Voltage-Controlled Buck Power Stage

This paper investigates the dynamic properties of the photovoltaic-generator-interfacing voltage-controlled buck power stage operating in both the maximum and limited power point tracking modes. The photovoltaic generator (PVG) is known to possess both current- and voltage-source properties with respect to its maximum power point. While voltage-fed operation is conventional, current-fed action is nontrivial and is thoroughly analyzed in this paper. The photovoltaic-generator-interfacing converter is formed by adding a capacitor at conventional voltage-fed converter input terminals, turning it into a current-fed power stage. During the maximum power point tracking phase, converter input voltage is regulated, possessing nontrivial dynamics. The situation is burdened further when output-voltage control should be alternatively realized to limit the voltage of the converter terminating the energy storage element. It is shown that both the photovoltaic generator and the terminating energy storage greatly affect the combined system dynamics. Parallel as well as cascaded control arrangements are proposed to support dual-mode system operation. Extended experimental results are shown to enforce presented theory and reveal nontrivial dynamics-related issues.

Grid Connected WECS with A Five Level DCMLI using PID Controlle

Thispaper deals with the analysis, modeling and control system for permanent magnet synchronous generator (PMSG) based wind turbine connected to the grid. A wind energy conversion using DC-DC Buck- Boost Converter for permanent magnet synchronous generator (PMSG) based variable speed wind energy conversion system (WECS) has been proposed which is integrated with grid using five-level diode clamped multilevel (DCMLI) inverter. In this work the instantaneous values of input side current and voltage of DC-DC buck-boost converter are utilized for implementing the PID controller. The proposed work is verified by the simulation in Powersim.

A High Voltage Self-Biased Integrated DC-DC Buck Converter With Fully Analog MPPT Algorithm for Electrostatic Energy Harvesters

This paper presents a high voltage and low power inductive DC-DC buck converter for interfacing electrostatic energy harvesters. The system, implemented in TSMC 0.25 µm BCD, can convert input voltages from 5 to 60 V to recharge the energy storage system connected to the output. The system includes also a Maximum Power Point Tracking algorithm for matching the equivalent source resistance of harvester and AC-DC converter. Due to power consumption constrains, a conventional implementation of this algorithm, based on ADC, DAC and complex digital processing is replaced by a much simpler fully analog design. Measurements have shown a peak end-to-end efficiency of 88% with 99.8% MPPT peak efficiency.

An Electricity Parameter Measurement for Off-Grid PWM Converter

The input voltage of off-grid PWM converters has a great dynamic range in amplitude and frequency. In addition, the frequent changing of these parameters also makes it hard to measure preciously via traditional ways. Details of window function are presented. A modified FFT spectrum analyzing method using interpolation is also given and checked. Finally, a feasible solution which balances both precision and real-time data processing comes up considering the speed of MCUs mainly used in industry. Simulations and experiments show that this solution settles the troubles which cant be cleared up by traditional methods.

Dynamic Analysis of Buck-Based Photovoltaic Array Model

PV applications regularly require the control of the input voltage of DC-DC converters. Unlike conventional converter, in this study the input voltage is controlled and the output voltage is maintained constant. A linearized photovoltaic (PV) array model and buck converter with constant output voltage model were used in this paper to get the transfer function of the electronic converter and to design a voltage compensator to regulate the input voltage of the converter. Results were obtained and illustrated verifying the efficiency of the compensator used in enhancing the time-response performance of the buck-based PV system by reducing the over-shoot, settling and rising time. Nonetheless, enhancing the stability of the buck-based PV system. 

Matrix Converter Using Direct Svm Method with Input Power Factor Compensation

The matrix converter (MC) for motor drive applications and energy conversion systems is steadily increasing due to its main advantage of performing a direct coupling between two three-phase alternating current sources without the need of an intermediate direct current bus. The input filters characteristics design for matrix converter system: to reduce the high harmonic components at the main power supply current and to improve the input voltage distortion for matrix converter, the unity power factor at the main power supply side is only achieved at the high output load and decreases greatly at the light load conditions. This paper proposes a new direct space vector modulation (DSVM) method to achieve the required displacement angle between input voltage and input current of matrix converter. A new switching strategy is introduced based on the maximum compensated angle and for the controllable input power factor of matrix converter. The power factor compensation algorithms using the new DSVM method to achieve the maximum IPF are presented, in which compensation algorithm I is based on using the input filter and power supply parameters to estimate the optimal compensated angle. Compensation algorithm II is subsequently proposed using a proportional–integral controller to overcome drawbacks presented in compensation algorithm I. Simulation results with inductive load (RL) are shown to validate the effectiveness of the proposed method.

STROMBOLI®: a new platform for Isolated DC-DC Converters with reliable operation from −55°C up to 225°C

This paper presents a new high-temperature isolated DC-DC converter platform called STROMBOLI®. It also discusses how this converter can be associated with the various solutions proposed by CISSOID for Point-of-Load (POL) regulators that can be either linear or switched mode. STROMBOLI® has been optimized to efficiently convert input voltages up to 350V into multiple output voltages up to +/−25V. As an example, in a +/−12V symmetrical output configuration, standard STROMBOLI® can deliver 25W with efficiencies up to 70% at 225°C. The galvanic isolation between input and outputs is at least 10MΩ at 500V. As the main objective of this development was to provide designers with a solution highly flexible, scalable, and easily adaptable to their specific requirements, we selected well-known and robust flyback architecture. Efficiency has been optimized thanks to synchronous rectification. However it can be replaced by a standard rectification in order to reduce the bill-of-material (BOM). A magnetic feedback provides the output voltage temperature stability and the load regulation. STROMBOLI® also includes an Under-Voltage-Lockout (UVLO) function and the pulse-by-pulse current sensing provides intrinsic output current limitation in case of overload or short-circuits. STROMBOLI® is a state-of-the-art, turnkey reference design suitable for 225°C reliable operation and is part of high temperature DC-DC converters VOLCANO family.

새로운 변조방식을 사용한 단상 인버터 시스템

본 논문에서는 새로운 변조방식을 사용한 단상 인버터 시스템을 제안한다. 제안한 시스템은 buck-boost 변환기와 인버터로 구성되며 새로운 변조방식인 PWAM(Pulse Width/Amplitude Modulation)방식을 사용하여 제어한다. PWAM방식은 PWM(Pulse Width Modulation)방식과 PAM(Pulse Amplitude Modulation) 방식이 혼합된 새로운 변조방식이며 인버터의 입력단에 위치한 buck-boost 변환기는 일정한 직류전압을 입력으로 받아 가변 직류전압으로 변환한다. 인버터는 buck-boost 변환기에서 출력된 가변 직류전압을 입력으로 하며, PWM 구간에서는 PWM 스위칭을 하고 PAM 구간에서는 인버터가 스위칭을 하지 않음으로써 정현 교류전압으로 변환한다. 제안한 PWAM방식을 사용한 단상 인버터 시스템은 PAM 구간에서 스위칭 동작을 하지 않으므로 기존의 방식에 비해 스위칭 횟수가 감소하여 스위칭 손실을 줄일 수 있다.

신재생에너지 연계용 고효율 승압형 DC-DC Converter 회로 토폴로지 개발

본 논문에서는 배터리전원 또는 태양광과 연료전지 등의 신재생 전원에서 발생되는 저전압 에너지원을 고전압으로 변환하기 위한 DC-DC 컨버터의 설계에 대해 연구하였다. 입력 DC24[V] 전압을 출력전압 400[V]로 변환하기 위한 H-브리지 컨버터의 회로 토폴로지에 있어 출력측 전력 및 전압을 제어하기 위해 위상천이제어를 적용하여 구현하였다. 제안된 컨버터 시스템의 장점으로는 전류 스트레스 감소 및 높은 효율성, 신뢰성 및 단순화된 관리뿐만 아니라 저렴한 비용 등을 들 수 있으며, 가정용 전력 생산을 위한 시스템으로 매우 유용하다는 것을 알 수 있었다.

Over-modulation phenomena and its influence on the pulse width modulated single-phase inverter output voltage

This paper describes analysis of the pulse width modulated single-phase inverter output voltage. By using the over-modulation principle the low THD distortion of the output voltage appears but the first voltage harmonic is increased. The root mean square (RMS) component of the output voltage is also increased. Due to this phenomenon the dc converter input voltage can be decreased, which is always welcomed.

Voltage regulation of photovoltaic arrays: small-signal analysis and control design

This study deals with the regulation of the output voltage of photovoltaic (PV) arrays. As a case study, the DC-DC buck converter is used as an interface between the PV array and the load, but other types of converters can be used for the same purpose. The input voltage of the converter is controlled in order to regulate the operating point of the array. Besides reducing losses and stress because of the bandwidth-limited regulation of the converter duty cycle, controlling the converter input voltage reduces the settling time and avoids oscillation and overshoot, making easier the functioning of maximum power point tracking (MPPT) methods. The voltage regulation problem is addressed with a detailed analysis that starts with the modelling of the PV array and the converter. This analysis is followed by study, design, simulation and practical experiments of three closed-loop control strategies for the buck converter. Control stability and implementation considerations are presented.

Dynamic analysis of the input-controlled buck converter fed by a photovoltaic array

The control of the input voltage of DC-DC converters is frequently required in photovoltaic applications. In this special situation, unlike conventional converters, the output voltage is constant and the input voltage is controlled. This paper deals with the analysis and the control of the buck converter with constant output voltage and variable input.

An Alternative Energy Recovery Clamp Circuit for Full-Bridge PWM Converters With Wide Ranges of Input Voltage

A full-bridge DC-DC converter employing a diode rectifier in the output experiences a severe voltage overshoot and oscillation problem across the diode rectifier caused by interaction between junction capacitance of the rectifier diode and leakage inductance of the transformer. The pronounced reverse-recovery current of high-power diodes significantly contributes to these issues by increasing power lossand voltage overshoot. Conventional energy recovery clamping circuits suffer from high voltage overshoot if the converter input voltage is wide. In this paper, a novel energy recovery clamp circuit is proposed to overcome this problem. The proposed circuit requires neither active switches nor lossy components. Therefore, the proposed circuit is very promising in high-voltage and high-power applications. Performance of the proposed circuit is verified both theoretically and experimentally with a 70-kW DC-DC converter.

A Single Switch Split DC-Rail Boost Converter Topology Operated Under Steady-State Unbalanced Load Conditions in Discontinuous Conduction

A single switch split dc-rail boost converter topology is described that uses a mutually coupled two winding inductor to balance the voltage drop across both of its capacitor smoothed split dc-rail input and output voltage terminals. The operation of the converter topology is described in discontinuous conduction with an unbalanced output load in steady-state. The resultant converter topology obtains balanced input and output voltages under extreme unbalanced load conditions without requiring extra converter control features. A current sharing action is described between the two coupled windings during both the switch on-time and off-time. This action is responsible for the voltage balancing feature of the converter when the converter load is unbalanced between the two output dc voltage rails. Simulations and experimental results are used to illustrate the nature of the winding current waveforms that produce this current sharing action. Load imbalances exceeding 3:1 can easily be compensated for, and simulations and experimental results show that typical deviations of the converter input and output voltages can be limited to within the range 1% to 8% for load imbalances of up to 2:1. The voltage imbalance experienced in the two dc rail output voltages is subject to design choices and linked to the winding leakage inductance and dc voltage gain.

A control method of matrix converter for plasma control coil power supply

Since a tokamak fusion reactor will require a fast response and precise power supply to control the coil current, we propose a matrix converter configuration, as a candidate, having a filter in a load side and smaller elements than a conventional matrix converter. Coil current control performance of the candidate converter has been evaluated by a simulation model using the code “PSCAD/EMTDC.” Simulated circuit parameters were: 30 mH for the load coil, 1 kV for the matrix converter input voltage, and ∼100 A for the output coil current. The PWM (pulse width modulation) control using triangular carrier modulation of a 10 kHz carrier frequency was adopted as the control method. The simulation results show that the settling delay time of coil current in the step variation is ∼1 ms. The transient response performance of the simulated coil current to the reference current was good. We have come to a condition that the matrix converter can be applied to the plasma control coil power supply.