Pulse Width Modulation Switching Research Articles

A New Carrier-Based Pulse Width Modulation Scheme with Reduced Output Voltage Total Harmonic Distortion for Multi-Level Inverters

This paper proposes a novel Pulse Width Modulation (PWM) switching technique based on Optimized Carrier Peaks-PWM (OCP-PWM) which can be used to control both single phase and three-phase multilevel inverters. The proposed PWM scheme is designed according to multi-peak selection on carriers a way to define the optimum values for carrier peaks and then minimizing the output voltage Total Harmonic Distortion (), switching frequency (f s), and also switching losses, in comparing with the other carrier-based PWM methods. To examine the performance of the presented PWM scheme, a five-level converter has been employed including six power MOSFETs to produce five level in the output. In comparison with typical PWM switching methods for single-phase inverters, the presented PWM scheme produces low harmonic components in the output voltage. To investigate the reliability of the presented PWM scheme for single-phase five-level converters a 2.5kVA/400 V prototype is carried out by applying a TMS320F28335 digital signal processor.

The New Control Scheme for the PV and Wind Hybrid System Connected to the Single Phase Grid

The proposed system comprises of the hybrid (PV and wind) system for 1 kw is integrated with the single phase grid. The new control scheme sine pulse width modulation (SPWM) switching with a deadbeat based PI controller is designed to a DC/AC single phase inverter. This controller is used to pure sinusoidal output voltage with low total harmonic distortion (THD), fast dynamic response control techniques and to keep the power output constant if any variation in the input from the PV and wind system occurs, and the output voltage at the grid remains constant. Even when the load varies, the sinusoidal voltage output maintains 230Vrms with 50 Hz frequency and also low THD is 2.54%. This controller proves the stiffness and robustness characteristics for maintaining the output voltage at desired value with low harmonics.

Analisis Pengaturan Parameter Sinusoidal Pulse Width Modulation pada High Precission Closed Loop Full Bridge Bipolar Inverter untuk Pembangkit Tegangan Tinggi Berfrekuensi Tinggi

The application of high voltage becomes more important and wider. High voltage is needed in the process of reducing air contaminants, waste treatment, sanitation, disinfecting microorganisms, testing for insulating high voltage equipment, and transmitting electrical energy. The problem of high voltage AC generation system is still in a large scale, static, not portable, and very expensive. This paper presents an analytical design of a high-voltage AC high-frequency based on power electronic. It is portable, less expensive, and eaasier to control the amplitudo and frequency. The application of the Full Bridge Bipolar Inverter topology with the Sinusoidal Pulse Width Modulation switching method provides variable sinusoidal AC voltage outputs (Vo) on its amplitude and frequency. The Tesla Coil Transformer amplifies the amplitude in accordance with the classification of the high voltage AC in the order of Kilo Volt. The Closed Loop control system in the Bipolar Inverter Full Bridge topology provides high accuracy results between the given setting values and the actual amplitude output and the expected high-frequency AC voltage. Analysis of the SPWM switching pattern parameter settings shows stability for several loading variations

FPGA-Based High-Definition SPWM Generation With Harmonic Mitigation Property for Voltage Source Inverter Applications

High-resolution sinusoidal pulsewidth modulation (SPWM) switching is beneficial in order to achieve compact size and fine sinusoidal output of dc-ac converters. In this article, a novel field-programmable gate array (FPGA) based high-definition SPWM (HD-SPWM) architecture is proposed for adopting a scheme of integrating a lower frequency PWM train to a high-frequency SPWM train in order to suppress inverter output harmonics while achieving high resolution output. An optimized FPGA-based two-stage finite-state-machine (FSM) architecture is designed, where the initial stage decides pulsewidths of a lower frequency PWM train based on the premeditated pulsewidth of the high-frequency SPWM train, whereas in the final stage, lower frequency PWM pulsewidths are integrated with the high-frequency SPWM pulsewidths to generate updated pulsewidths of high-frequency SPWM, i.e., HD-SPWM. Moreover, a preformulation mathematical model is established for the calculation of duty-cycle count values of pulse trains to support the online adjustment of modulation index (MI) of the HD-SPWM. The proposed generation has the benefits of harmonic mitigation, online fine adjustment of MI, low-processing time, and requirement of a minor segment of a medium-sized FPGA; thereby, providing a good tradeoff between larger designs and higher performance. Theoretical calculations, characteristics, and design contemplations are specified, and the HD-SPWM generation is demonstrated through experimentation with a Xilinx Spartan-3 FPGA board.

Power Device Temperature-Balancing Control Method for a Phase-Shift Full-Bridge Converter

In this paper, a switching method is proposed for power device temperature-balancing in a phase-shift full-bridge (PSFB) converter. PSFB is commonly used for applications that require high efficiency, because a zero-voltage switching (ZVS) operation is possible on the primary-side. In PSFB, the circulation current complicates ZVS under a light-load condition, which generates heat. Meanwhile, the heat generated in PSFB creates a temperature deviation between the lagging leg and the leading leg, which shortens the lifetime of the power device, thereby reducing system reliability and efficiency. To solve this problem, previous studies applied a pulse-width modulation (PWM) switching method for light and medium loads, and a phase-shift switching method for the region where ZVS is possible. Although this method has the advantage of easy control, the maximum temperature of the legs of the PSFB increases with medium loads. In this paper, a temperature-balancing algorithm—a temperature-balance control—is proposed to decrease the leg temperature using switching based on position exchanges of the leading leg and lagging leg along with PWM switching. Temperature-balance control minimizes leg temperature deviation under light load conditions. The proposed control method provides a minimum temperature difference between the two legs and high efficiency.

Design and Construction of an Inverter for University ICT Loads

In trying to restore a stable power generation in this part of the world for effective research studies and to improve administrative duties in the University of Nigeria Nsukka, this paper discusses the design and construction of a single phase inverter for information communication and technology equipment’s (ICT) which includes printers, computers, and network switches etc. The inverter system converts the DC voltage from a battery to AC voltage. The output is a pure sine wave, with the voltage and frequency of the standard grid (50Hz, 230V). A pulse width modulated (PWM) switching scheme together with a full bridge converter and filter is use to realize this design. The sinusoidal pulse width modulation (SPWM) switching scheme is the main logic control circuit of this inverter and provides a PWM output using operational amplifiers and microcontroller. This logic circuit is connected to a driver circuit to ensure sufficient gate driving current and voltage for the full bridge converter (H-bridge) switches (power MOSFET). The pulse signals are used to drive MOSFET in a H-bridge configuration to produce an output that is bipolar The output of this inverter switches from positive to negative (bipolar). This output from the MOSFET when filtered produces a sine wave output. This project is implemented and simulated using MATLAB simulation software.

Iron Loss Modelling of Electrical Traction Motors for Improved Prediction of Higher Harmonic Losses

A Finite Element (FE) modelling approach is presented to account for the core losses in electrical machines that are generated by higher harmonic frequencies, for example those caused by Pulse Width Modulation (PWM) switching or by space harmonics due to the machine geometry. The model builds further on a post-processing calculation tool that was recently developed to take into account the magnetic skin effect in electrical steel laminations at high frequencies, and extends this by a more detailed loss analysis of the minor hysteresis loops that are caused by the higher harmonics. Further, these tools for high-frequency loss analysis are integrated into a complete electrical machine model with separate consideration of the major and minor loops. The modelling approach relies strongly on extensive magnetic measurement data of the electrical steel, in order to accurately predict the different loss components for minor hysteresis loops as a function of the DC bias field, frequency and amplitude of the minor loop. Results from the model are shown for an automotive traction motor, illustrating the losses caused by PWM harmonics and demonstrating the relevance of including the skin effect in these calculations.

Synchronous Reluctance Motor Parameter and State Estimation Using Extended Kalman Filter and Current Derivative Measurement

The synchronous reluctance motor is becoming a very attractive alternative to the ac induction machine. This is due to the lack of rare-earth metals in their construction and a higher efficiency, which was brought about by recent progress in rotor design. However, in order to achieve an efficient and low-cost operation of the synchronous reluctance motor drive, an adaptive sensorless algorithm should be utilized to cope with machine nonlinearities. This article describes an adaptive observer, which can provide an estimation of rotor position and speed, as well as core loss and inductance parameters. A modified pulsewidth modulation (PWM) switching scheme and a current derivative measurement method are proposed, together with an extended Kalman Filter design. Experimental results are shown to demonstrate the method performance and feasibility.

A Bidirectional Three-Phase Push–Pull Converter With Hybrid PPS-DAPWM Switching Method for High Power and Wide Voltage Range Applications

High-power isolated bidirectional dc-dc converters with wide voltage range are attracting increasing attention in many applications. The bidirectional three-phase current-fed dc-dc converters are known to be suitable for wide voltage range applications compared to dual active bridge based converters, having advantages of reduced device current ratings and prevention of transformer saturation due to high impedance nature. However, when the duty cycle becomes lower than 0.33 or higher than 0.66, power transfer capability is limited, and the efficiency is significantly reduced due to increased circulating current, which has rarely been discussed so far. In this article, a hybrid dual-asymmetrical pulsewidth modulation (DAPWM) and pulsewidth modulation plus phase-shift (PPS) switching method is proposed for efficiency improvement of the bidirectional three-phase push-pull converter with very wide voltage range. A seamless mode change method between PPS and DAPWM is also proposed for minimizing the transient state. Further, through current waveform and power flow analysis, the leakage inductance along with transformer turn ratio are designed to minimize the root mean square (rms) current of devices, while having the capability of transferring the desired power and limiting the slew rate of transformer winding current under wide voltage range operation. Experimental results from a 22-kW prototype are provided to validate the proposed concept.

Analysis of Switching Sequence Operation for Reduced Switch Multilevel Inverter With Various Pulse Width Modulation Methods

Pulse Width Modulation (PWM) methods are used to control the switching sequence operations of conventional Multilevel Inverter (MLI) and Reduced Switch Multilevel Inverters (RSMLI). Many researchers proposed various RSMLIs with their switching sequence operation and PWM control techniques. But, the switching operations of RSMLIs are not similar to conventional MLIs which are major problem of switch control. Logical equations are proposed for the operation of RSMLIs with the multi carrier pulse width modulation methods like, Alternative Phase Opposition Disposition (APOD), Phase Opposition Disposition (POD) and Phase Disposition (PD). To operate the individual switch in RSMLI, logical operators are used to produce required pulse sequence from the sequence of PWM method and their analysis is not present in previous works. The proposed methodology and binary representation of PWM method are analyzed on various RSMLIs for 7 level output voltage. Control of individual switching sequence and the operation of RSMLIs are simulated using MATLAB/Simulink. THD comparison is presented for RSMLIs with various PWM methods.

Estimation of PWM-Induced Iron Loss in IPM Machines Incorporating the Impact of Flux Ripple Waveshape and Nonlinear Magnetic Characteristics

This article presents an improved estimation model to predict the additional iron loss due to pulsewidth modulation (PWM) switching in interior permanent magnet (IPM) machines. The input current including the predicted PWM-induced current ripple is fed to two-dimensional (2-D) finite-element analysis to calculate the PWM-induced flux ripple distribution in the analyzed machine. A special frequency decomposition method is proposed to separate the predicted flux ripple into 1x and 2x PWM frequency components. Combining these results with the modified dynamic Jiles-Atherton model, the PWM-induced iron loss is calculated incorporating the impact of the actual flux ripple waveshape and the lamination steel's nonlinear magnetic characteristics. Experiments have been conducted to evaluate the prediction accuracy and investigate the impact of several factors on PWM-induced core losses (i.e., both iron and magnet loss) in IPM machines. These results demonstrate that the model offers promising estimation accuracy over a wide range of machine and inverter operating conditions.

Fast SPICE-Compatible Simulation of Low-Power On-Chip PWM DC–DC Converters With Improved Ripple Accuracy

The circuit averaging technique has long been used as the basis for modeling the behavioral effects of switched-mode pulsewidth-modulated (PWM) dc–dc power converter circuits due to its simplicity and efficiency in simulation. However, circuit-averaged models struggle to capture the effects of higher order harmonics on the output waveforms. Alternatively, multiharmonic models that capture high-frequency characteristics of output waveforms are typically very complex and computationally expensive. A general, efficient, and accurate multiharmonic modeling and simulation technique for low-power on-chip PWM dc–dc converters is presented in this article. The technique is based on the large-signal averaged model of the PWM switch cell and on the Fourier series expansion of the typical converter waveforms. Its applicability range includes current-mode-controlled dc–dc converters. The method is exemplified on a buck and on a boost converter and achieves a speedup of one order of magnitude with an accuracy loss below 3% over the transistor-level simulation. The method accounts for nonideal circuitry and supports any number of harmonics.

Design and development of PWM switching for 5-level multiphase interleaved DC/DC boost converter using FPGA

<p>The continuously increasing demand for control on electric power equipment has led to the rapid technological development in various applications such as renewable energy, electric drives, and communication. Pulse Width Modulation (PWM) switching is an important technique to control the output voltage. PWM signals can either be generated using digital controller or analog controller. Digital controllers are widely used to generate PWM signals due to their reliability in solving complex algorithms within short amount of time. Multiphase boost converter is capable to overcome high input current ripple, current stress and semiconductor losses in conventional boost converter. This paper proposes a PWM switching scheme for multiphase interleaved converter using Field Programmable Gate Array (FPGA). The proposed switching scheme uses PWM switching technique that is implemented by programming Altera DE2-70 board. The duty cycle can be easily adjusted using assigned switches on the Altera board. For validation, switching frequency was set to 100 kHz, and then switching signal was observed using oscilloscope.</p>

Dynamic Average-Value Modeling of Three-Level T-Type Grid-Connected Converter System

Three-level T-type converter (3LT2C) possesses the advantages of simple structure and high efficiency, which makes it appealing especially in low- and medium-voltage applications. Dynamic average-value modeling (AVM) has become an effective methodology for small-signal analysis and large-signal transients of power electronic subsystems in power systems applications. In this paper, a dynamic AVM for the three-phase 3LT2C is presented for the first time. The proposed model is derived using the state-space average approach, where the averaging process is implemented over each pulsewidth modulation switching period. The ac- and dc-side dynamics are represented by a fourth-order time-invariant system. The accuracy of the developed AVM is validated against the detailed switching model, while demonstrating its computational advantages. The new model is also verified using experimental tests on a prototype.

The performance analysis of dual-inverter three phase fed induction motor with open-end winding using various PWM schemes

Induction motor with scheme open end winding (OEW) has attract many attention in the recent time as a compromising alternative of multi-level inverter. The structure contains of simplicity in generating multi-level inverter and has potential ability to obtain a better quality output due to higher number of the available switching states and voltage vectors.’ Based on the method to divide the voltage references, various Pulse Width Modulation (PWM) schemes for the dual-inverter fed induction motor with OEW have been discussed in this paper. The first one is developed by equally splitting the voltage references to two inverters and termed as Equal Reference Division Pulse Width Modulation (ERD PWM). In the second PWM scheme, the voltage references are devided according to moduation index (M). At M > 0.525, one inverter is modulated using maximum voltage reference while the other one inverter is modulated proportionaly according the change of voltage reference. The PWM scheme is named as Unequal Reference Division Pulse Width Modulation (URD PWM). In the third PWM scheme, the two inverters are modulated using different method, i.e one inverter is controlled in slow switching PWM and the second inverter are modulated using fast switching PWM. Hence the thirs PWM is named as Mixed Devider Switching (MDS) PWM scheme. The results shows that the MDS PWM provide the best voltage Total Harmonic Disortion (THD) performance among the three PWM schemes. Further the speed-torque acceleration shows that the dual-inverter fed structure is able to control the speed to reach the desired speed at t = 0.25 s. The speed is able to adjust when the load is apply at t = 0.4 s. The motor current THD and the mechanical torque reveal that the MDS PWM provide the best among three PWM schemes.

Soft Switching Bidirectional Converter for Reflex Charger With Minimum Switches

In this article, a new soft switching bidirectional dc–dc converter for battery charger application based on reflex charge technique is proposed. The proposed bidirectional dc–dc converter applies flyback converter to provide negative current pulses for reflex charge method while providing zero-voltage switching (ZVS) for the buck converter switch which is used to control charging current. The flyback converter switch is also soft switched. Flyback converter switch operates under zero-current switching (ZCS) turn- on and ZVS turn- off conditions. The proposed bidirectional converter applies only two switches to implement a fully soft switched pulsewidth modulation (PWM) bidirectional converter. Hence, the proposed topology provides a fully soft switched bidirectional converter with minimum number of switches using PWM control method. The proposed converter is implemented, analyzed, and experimental results are presented. The experimental results verify the theoretical analysis presented in the article. Efficiency comparison performed shows proper efficiency of proposed converter while applying minimum number of switches.

Near-Unity Power Factor, Voltage Step-Up/Down Conversion Pulse-Width Modulated Switching Rectification for Wireless Power Transfer Receiver

The pulse-width modulated (PWM) switching rectification that can achieve a high power factor (PF) for increasing the energy transfer efficiency between an LC resonator and a rectifier and voltage step-up and -down conversion is proposed for a wireless power transfer (WPT) receiver. The proposed method can emulate the switching rectifier as a resistive load by using an inductor and integrated phase synchronizers. Additionally, similar to a switched-inductor converter that controls the duty cycle ratio ( D ), the proposed PWM rectifier can control the output voltage V OUT when the input is a rectified, wirelessly coupled voltage instead of a constant voltage. Thus, unlike a conventional PWM switching rectifier for ac mains, an additional voltage conditioning circuit would not be needed after the proposed rectifier for WPT. The proposed PWM switching rectification is implemented in the AMS 0.18 μ m 1.8 V/5 V CMOS process. PF = 1 is measured, indicating the most efficient energy transfer, compared to only 0.55–0.65 in a peak detection rectifier. Additionally, 88.2% of peak power conversion efficiency of the switching rectifier is achieved, and the maximum output power is 80.3 mW at 500 kHz of the WPT frequency. Moreover, the measured voltage conversion ratios ranging between 0.73× and 2× are demonstrated in this paper.

Fast Switching Valve Utilization to Control Pneumatic Cylinder Speed

The position and speed of the piston of pneumatic cylinder are very important parameters in evaluating the pneumatic system performance. Utilization of Pulse Width Modulation (PWM) technique to control the Fast Switching Valve (FSV) usually causes fluctuation in the piston motion and accordingly, the system performance deteriorates. The objective of this work is to introduce a novel PWM control technique considering the suitable duty cycles according to the switching frequency in order to improve the FSV characteristics and reduce piston speed fluctuation. A test rig for a simple pneumatic circuit with an FSV as a control element has been designed and realized. The displacement of the piston is measured using a Linear Wire Potentiometer Transducer (LWPT), while its derivative is used to estimate the speed considering a low pass filter to reduce the effect of piston position signal noise. A nonlinear mathematical model is introduced and experimentally validated. The results of both computer simulation and experimental measurements show that the integration between fast switching valve and PWM control signal leads to a quasi-linear relationship between duty cycle and piston speed. Moreover; results proved the successful control of piston speed based on the correct duty cycle and valve switching frequency.

A Hybrid Sensorless Controller of an Interior Permanent Magnet Synchronous Machine Using Current Derivative Measurements and a Sliding Mode Observer

The ability of current-derivative based speed and position estimation of IPMSMs over a full speed range has recently been demonstrated. However, at high-speeds, the modulation index becomes limited because the extension of the zero-voltage vectors and current waveforms become distorted. This article proposes a hybrid position and speed estimation technique which uses current derivatives at the first active-voltage vector during each pulsewidth modulation (PWM) switching period for enhancing the performance of a sliding mode observer at low and very low speeds. This article presents the theoretical analysis and experimental evaluation of the proposed sensorless method for an IPMSM over a full speed range from zero to rated speed. The experimental results have shown a significant improvement in speed and position estimation accuracy at low speeds and a considerable reduction of the current distortion over the full speed range, compared to the existing fundamental PWM excitation sensorless control methods.

Research on Topology and Modulation Control Method of a Novel Three-Level Current-Fed DCDC Converter

Multilevel current source converter has the benefits of high output capacity, low current switching stress and low harmonic or ripple content. This paper presents a new topology of three-level current-fed DC/DC converter for superconducting magnetic energy storage application. In this topology, a superconducting inductance acting as a constant current source and a shunt inductance acts as current divider ensure current flows through the power switch components equally to generate immediate level of current. A novel kind of pulse width modulation (PWM) switching strategy for the current instantaneous control of the current source converter was proposed. The modulation switching strategy proposed is able to effectively control the DC current output of the converter. Also, due to the both of proposed topology and control method are quite a simple, it can be easily realized in the practice. Simulation results prove the feasibility and validity of the proposed topology and modulation strategy