Current Pulse Width Modulation Research Articles

Power quality improvement by using photovoltaic based shunt active harmonic filter with Z-source inverter converter

Introduction. The major source of energy for a long time has been fossil fuels, however this has its drawbacks because of their scarcity, exhaustibility, and impossibility of reusing them. Presently, a shunt active harmonic filter-equipped two-stage solar photovoltaic system is showing off its performance shunt active harmonic filter. The global power system has been impacted by current harmonics during the most modern industrial revolution. Novelty. The proposed work is innovative, by adopting the hysteresis modulation mode with Z-source inverter to enhance the performance of the system. Furthermore, the shunt active harmonic filter also get assists in this system for better improvement in the quality of power. Purpose. By incorporating an impedance source inverter and a photovoltaic shunt active harmonic filter methods, harmonic issues are mitigated. Methods. Load compensation is one of the services that the shunt active harmonic filter offers, in addition to harmonic compensation, power factor correction, and many other functions. The current pulse width modulation voltage source inverter method is more expensive, requires two converters owing to its two-stage conversion, has significant switching losses, and has a low rate of the reaction. The new model, in which the voltage source inverter is substituted out for a Z-source inverter converter, has been developed in order to address the problems of the existing system. Results. Rather than using a hybrid of DC-DC and DC-AC converters, the suggested system uses a shunt active harmonic filter that is powered by a photovoltaic source using a Z-source inverter. Utilizing Z-source inverter helps to address the present issues with conventional configurations. Practical value. By using software MATLAB/Simulink, this photovoltaic shunt active harmonic filter technique is analyzed. Shunt active harmonic filter, which produces compensatory current from the reference current obtained as from main supply, is powered by the photovoltaic array.

A new digital resonant current controller for AC power converters based on the advanced Z-transform

In this paper, we present a new digital resonant current controller that can be applied in single-phase and three-phase alternating current (AC) power converters, based on voltage source inverters (VSI) with pulse width modulation (PWM). Since power converters based on PWM introduce fractional time delays regarding the sampling period (Ts), because of the current sampling and PWM command updating techniques that are employed, there is a need to develop analytical tools for precise modelling of these types of delays. To achieve this, the advanced Z-transform is applied in order to model the AC controllers in VSIs with PWM for the general case of a fractional time delay, including power converters with current sampling within a PWM period at any chosen time instance. This new approach to power converter modelling and current sampling allowed us to develop a modified resonant AC current controller for a VSI with RL load, based on the pole-placement parameter tuning method. It includes fractional time delays, which are conventionally employed in the power converter design, in the controller parameter derivations, and introduces the minimal order resonant controller that enables strict placement of all closed-loop control system poles. Simulations and experimental tests are carried out to show the improvements introduced by novel solution in this paper compared with conventional resonant current controllers. In the analysis of dynamic performance and robustness, in this paper conventional indices are applied to compare the proposed controller with a conventional design.

4.1: Invited Paper: Active Driving Micro LED by TFTs Technology

Micro Light Emitting Diode (Micro LED) displays are expected to become the next generation display technology due to the potential advantages such as lower power consumption, higher resolution, longer life time and faster response speed. Active driving Micro LED by thin film transistors (TFTs) is one of the bottlenecks to realize the productization of Micro LED displays. It is thought that Micro LED should be driven by the constant current pulse width modulation (PWM) method. The PWM driving methods of Micro LED can be furthermore divided into digital method and analogical method. This report will introduce our progress and thinking on active driving Micro LED by TFTs technology.

A Novel Zero-Sequence Current Elimination PWM Scheme for an Open-Winding PMSM With Common DC Bus

This paper introduces a novel pulsewidth modulation (PWM) scheme for an open-winding permanent magnet synchronous machine (OW-PMSM) driven by dual two-level three-phase inverter with common dc bus, which can effectively deal with the inherent zero-sequence current (ZSC) problem. Based on the conventional symmetrical unipolar double-frequency sinusoidal PWM scheme with an appropriate phase shift, the common mode voltage (CMV) of two inverters remains same and cancel out each other to eliminate the modulated zero-sequence voltage (ZSV) disturbance source. In this case, the double-frequency effect can be retained to reduce the ac side current ripple and suppress both corresponding motor vibration and acoustic noise, which is advantageous to improve the synthetic performance of motor. The dc-bus voltage utilization of the novel PWM scheme is proved to reach the same maximum value comparing to the conventional modulated ZSV elimination scheme. Meanwhile, a zero-sequence controller is designed to suppress ZSC by further adjusting the two CMVs to counteract other zero-sequence disturbance sources. To verify the analysis, the proposed PWM technique associated with the control method is implemented in an OW-PMSM experimental setup to validate the superiority of the proposed method.

A Single-Inductor Dual-Input Dual-Output DC–DC Converter for Photovoltaic and Piezoelectric Energy Harvesting Systems

A single-inductor dual-input dual-output (SI-DIDO) dc–dc converter for photovoltaic and piezoelectric energy harvesting systems is proposed. The SI-DIDO dc–dc converter uses buck-boost topology. A new algorithm is proposed to share the single inductor between all the inputs and outputs in one switch cycle. Light-load or heavy-load mode is determined by current-mode pulse width modulation (PWM) control. Moreover, a delay lock loop (DLL)-based zero-current detector (ZCD) is proposed to lock the pre-opening time of the comparator. Measurement results show that the peak efficiency of the proposed SI-DIDO buck-boost dc–dc converter is 88.1%.

Control Techniques and Power Factor Correction Methods: A Review

The ratio of real power flowing into the load to the apparent power in a circuit is referred to as the power factor (PF). It has no unit as its values lie between 0 and 1. Power factor correction (PFC) leads to a reduction in apparent power drawn from the ac source which in turn saves energy and minimizes the transmission losses. This paper reviews various methods used for PFC as well as the various control measures for power factor. The correction methods include distributed PFC, group PFC, centralized PFC and combined PFC. Distributed PFC is applicable to large electrical equipment with constant load and power with long connection times. Combined PFC is the hybrid between a distributed and a centralized correction method. Peak current control technique makes use of constant switching frequency even though, the presence of sub-harmonic oscillations at a duty cycle greater than 50% is a disadvantage. The presence of constant switching frequency and better input current waveforms are some of the applications of average current control. In the discontinuous current pulse width modulation (PWM) control, the internal current loop is completely eliminated so that the switch is at a constant frequency. In nonlinear carrier controllers, the duty ratio is determined by comparing a signal derived from the main switch current with a periodic nonlinear carrier waveform. Therefore, combined PFC and nonlinear carrier controllers are more accurate PFC methods for the power plant because they employ a high power factor boost converter with low total harmonic distortion for installations of large equipment with a constant load. This research paper forms a basis for power system planning as it assists in recommending the appropriate and adequate technique(s) for correcting and controlling the pf of the factory.

Sample-Averaged Zero-Sequence Current Elimination PWM Technique for Five-Phase Induction Motor With Opened Stator Windings

The five-phase dual-inverter connected to the five-phase open-end winding induction motor (FPOEWIM) with a single dc source could result in the flow of common-mode current (CMC) through the common dc bus and motor phase windings. In addition, the FPOEWIM drive contains third-harmonic content which do not contribute for torque generation in a distributed wound motor. So, to nullify the CMC as well as the third-harmonic content the sample-averaged zero-sequence current elimination (SAZE) pulsewidth modulation (PWM) technique is proposed in this paper. Wherein, the concept of alternative clamping of the inverters is used with the generation of virtual vector to eliminate third-harmonic content and the effective time region is moved to eliminate the CMC in average sense. The detailed analysis of the proposed SAZE PWM technique is presented along with the simulation results and experimental verification.

Switching Frequency Dynamic Control for DFIG Wind Turbine Performance Improvement Around Synchronous Speed

In a doubly-fed induction generator (DFIG) wind turbine (WT), large thermal and mechanical oscillations occur around synchronous speed due to the nearly zero-frequency current circulating between rotor windings and rotor-side converter (RSC). A switching frequency dynamic control technique is proposed in this paper to overcome the problem. The basic idea is to dynamically reduce the switching frequency during operation so that both the switching losses and dead-time effect of RSC can be reduced around synchronous speed. According to the characteristic that high-frequency pulse width modulation (PWM) harmonics in DFIG decrease significantly with rotor slip, there would be a new space for switching frequency reduction especially around synchronous speed. The reduced of switching frequency is actually determined by a tradeoff between the increase of both the stator current PWM harmonics and speed PWM ripples and the decrease of insulated-gate bipolar transistor temperature. Compared with the conventional technique with constant switching frequency, the new technique can effectively improve the system performance around synchronous speed including not only better thermal behavior and efficiency of RSC but also smaller current total harmonics and speed total ripples in generator. To clarify the method, first, the effects of switching frequency reduction on a DFIG WT system are investigated. Second, the criteria, control scheme, and procedure of the method are presented. Finally, experimental and simulation studies were carried out, and the results validate its feasibility and effectiveness.

Current mode pulse width modulation/pulse position modulation based on phase lock loop

Abstract In this paper, the fully integrated CMOS current mode PLL with current input injects at the place of input or output of the loop filter without summing amplifier circuit. It functions as PPM and PWM circuit is present. In addition, its frequency response is an analysis which electronic tuning BPF and LPF are obtained. The proposed circuit has been designed with 0.18 μm CMOS technology. The simulation results of this circuit can be operated at 2.5 V supply voltage, at center frequency 100 MHz. The linear range of input current can be adjusted from 43 μA to 109 μA, and the corresponding duty cycle of pulse width output is from 93% to 16% and the normalized pulse position is from 0.93 to 0.16. The power dissipation of this circuit is 4.68 mW with the total chip area is 28 μm × 60 μm.

Synchronous Double-Pumping Technique for Integrated Current-Mode PWM DC–DC Converters Demand on Fast-Transient Response

While the fast transient techniques have been extensively investigated, the research aiming at current-mode pulse width modulation (PWM) converters is relatively unexplored. This paper presents a synchronous double-pumping (SDP) technique for current-mode PWM dc–dc converters to achieve fast-transient response between different load conditions. The advantages and limitations of the existing conventional techniques are discussed and analyzed. With the proposed SDP technique, a nearly optimized recovery time speedup and voltage drop minimization for every different conventional current-mode converters can be obtained. The prototype chip was fabricated using a TSMC 0.35-μm CMOS process occupies the area of 2.242 mm2 including all bonding pads and ESD protection circuits. The output voltage ripple is measured about 15 mV in peak-to-peak value. The recovery time is 2.4 and 2.6 μs, respectively, in response to the 400-mA step-up and step-down load changes. Those are improved by a factor of 8.33 and 8.23, respectively.

High power factor and low total harmonics distortion using critical conduction mode boost converter-fed light-emitting diode driver

Summary This article presents a critical conduction mode (CRM)–based power factor correction (PFC) converter for multistring light-emitting diode (LED) driver. The application is targeted for high power projection application with brightness control of red-green-blue LED module. A pulse width modulation (PWM) technique is used for lighting control to achieve required brightness without compromising the efficiency (overall 82%) and power quality. The CRM boost PFC converter is used to feed a dual output flyback DC-DC converter, which supplies power to the forced cooling unit and the LED modules with galvanic isolation. The brightness control of LED is performed by synchronous buck converter using current PWM modulation. The CRM boost converter–based PFC converter is designed to operate in critical inductor current mode at universal AC mains. A prototype of proposed PFC converter–based LED driver is developed and experimentally verified. The power quality parameters of the proposed LED driver are evaluated at rated and light load conditions for universal AC mains (90–265 V) with brightness control. The power quality parameters are found within acceptable ranges of international harmonic standard IEC 61000-3-2 Class C for lighting systems.

Electrical Discharge Machining Flyback Converter using UC3842 Current Mode PWM Controller

This paper presents a current mode Pulse Width Modulation (PWM) controlled Flyback converter using UC3842 for Electrical Discharge Machining current generator control circuit. Circuit simplicity and high efficiency can be achieved by a Flyback converter with current mode PWM controller. The behaviors of the system's operation is analyzed and discussed by varying the load resistance. Matlab sofware is used to simulate the Flyback converter where a prototype has been built and tested to verify it's performance. DOI: http://dx.doi.org/10.11591/ijpeds.v5i2.6680

Analysis, Design and Implementation of an Improved ZVZCS-PWM Forward converter

In this paper an Improved Zero Voltage Zero Current Pulse Width Modulation Forward converter which employs a simple resonance snubber circuit is introduced. A simple snubber circuit consists of a capacitor, an inductor and two diodes. In proposed converter, switch Q1 operates at ZCS turn-on, and ZVS turn-off conditions and all-passive semiconductor devices operate at ZVZCS turn-on and turn-off state. The proposed converter is analyzed and various operating modes of the ZVZCS- PWM forward converter are discussed. Analysis and design considerations are presented and the prototype experimental results of a 100w (40 V/2.5A) proposed converter operating at 30 KHz switching frequency confirm the validity of theoretical analysis.

Design and Realization of the Small Power Two-Way DC Power Supply Based on UCC2800

To provide DC power to auxiliary equipment for a certain type of aircraft, according to the actual need, small power two-way dc power supply is designed using current mode pulse width modulator UCC2800. This paper introduces the basic principle of UCC2800, and also introduces the design and realization process of the low-power dc power supply based on UCC2800.

Novel Random-Switching PWM Technique With Constant Sampling Frequency and Constant Inductor Average Current for Digitally Controlled Converter

A new 2-D random-switching pulsewidth modulation (PWM) technique is proposed to reduce the dominant harmonic clusters while retaining constant average inductor current and constant sampling frequency. The special feature of constant average inductor current can reduce the output voltage ripple. Moreover, the controller parameters of a digitally controlled power converter are not required to change, which is quite essential to digitally controlled systems. Current random PWM methods are discussed and compared with the proposed method in this paper. It will be shown that the merits of the presented method include random-switching frequency, constant sampling frequency, and constant average inductor current. An field-programmable-gate-array-based digitally controlled buck converter experimental system has been set up. The specifications of the converter include <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">input voltage</i> = 5 V, <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">output voltage</i> = 1.5 V, and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">switching frequency</i> = 200 kHz. The proposed random-switching pattern is implemented by software. Experimental results demonstrate the effectiveness of the proposed random-switching pattern.

Development of High-Reliability EV and HEV IM Propulsion Drive With Ultra-Low Latency HIL Environment

This paper proposes an improved and robust method of minimizing the error in propulsion-drive line-currents that are reconstructed from a single dc-link current measurement. The proposed algorithm extends and then shortens the relevant phase pulse-widths in order to provide optimal sampling of the dc-link currents in two consecutive pulsewidth modulation (PWM) periods. The proposed PWM pattern control enables an improved sampling method which cancels offset jitter-like waveform errors present in all three reconstructed line-currents, which is due to a specific combination of nonsimultaneously sampled dc-link current and line-current PWM ripple. The improvement in induction motor drive accuracy using a single current-sensor and no shaft sensor (as proposed in this paper), over that of conventional methods, is shown. Thanks to an ultra-low latency hardware-in-the loop (HIL) emulator, the proposed algorithm, its implementation on a DSP processor, code optimization and “laboratory” testing were all merged into one development step. In order to perform final tests of the proposed current-reconstruction algorithm and to verify the usefulness of the developed HIL platform by means of comparison, experimental results obtained on a real hardware setup are provided.

Design of Portable On-Board Charger

To solve the key technology of automotive lithium battery charging system, a new kind of smart portable on-board charger is developed. This battery charger takes single-chip machine of freescale as system control chip, realizes closed-loop control of bus voltage by the voltage pulse width modulation chip TL494, realizes charger output with constant voltage, constant current and switch without disturbances by the current pulse width modulation chip UC3846, achieves master-slave control mode for multi–parallel machines through the CAN bus technology. In addition, the microcontroller program realizes the process monitoring and fuzzy PID regulation, the charging process has multiple intelligent protection and external regulatory functions. The experimental results show that with dual regulations of the software and hardware, the charger has the advantages of stable reliability, flexible operation and precise intelligence, an effective exploration of the battery charging technology is carried out.

Modelling the UCC3800 controller in SPICE with the electrothermal phenomena taken into account

A new electrothermal compact model of the current mode pulse width modulation controller—UCC3800—dedicated for SPICE is proposed in this paper. The form of this model is presented and described in detail. The results of the experimental verification of the model are also presented for the device operating in the test circuit. It is shown that self-heating influences essentially the characteristics of the considered device and the proposed model is of good accuracy. Copyright © 2011 John Wiley & Sons, Ltd.

Fuzzy Logic Control based Three Phase Shunt Active Filter for Voltage Regulation and Harmonic Reduction

This paper studies a Fuzzy Logic Control Based (FLCB) Shunt Active Filter (SAF) capable of reducing the total harmonics distortion (THD) in Power System (PS). SAF is one of the key controllers in Flexible Alternating Current Transmission System (FACTS) to control the transmission line voltage and can be used in PS to enhance the power transmission capacity and extend the transient stability. In order to improve the power factor, compensate the reactive power and suppress the total harmonic distortion (THD) drawn from a Non-Linear Diode Rectifier Load (NLDRL) of SAF, we propose a Hysteresis Current Pulse Width Modulation (HCPWM) technique which is used as control for the switches of the Voltage Source Inverter (VSI) or SAF. The synchronous reference D-Q frame theory is used to generate the reference compensating currents for SAF. A fuzzy logic based control is developed to regulate the voltage of the DC capacitor. The system with control scheme is implemented in Matlab/Simulink. The simulation results show the effectiveness of the proposed method for harmonic damping and voltage regulation.

A vector controlled current-source PWM rectifier with a novel current damping method

Three-phase current-type pulse width modulation (PWM) rectifiers are becoming increasingly popular as the front-end converter unit in power electronic systems due to tighter electromagnetic compatibility (EMC) regulations. In this paper the control of the current source PWM rectifier in the synchronously rotating reference frame is discussed. A control system is presented in which the active and reactive power are independently controlled with real and imaginary axis components of the supply current vector. A new damping method for supply current oscillations is introduced. The method operates in an open-loop manner and is very suitable for microcontroller implementation since the calculation power demand is low. Furthermore, it is shown that in the synchronously rotating coordinates, where the sinusoidal variables appear as DC quantities, the compensation of the reactive power drawn by the supply filter can be done very easily. The proposed control methods are realized using a single-chip Motorola MC68HC916Y1 microcontroller. The experimental tests show excellent performance in both steady state and transient conditions.