Pulse Width Modulation Type Research Articles

Auto tuning of PI Gains using Cuttlefish Optimization for DC Link Voltage Control in a 5-level HB MMC D-STATCOM

The performance of a Half Bridge (HB) Modular Multilevel Converter (MMC) for D-STATCOM application is studied in this article. For the control of MMC switches, the Carrier-Based (CB) Pulse Width Modulation (PWM) scheme has been selected as the appropriate method. There are two types of CB PWM schemes such as phase shift and level shift. Phase Disposition (PD), Phase Opposition Disposition (POD), and Alternate Phase Opposite Disposition (APOD) are the three different types of PWM that are used in level shifts. The PD CB PWM is projected in this work due to its simplicity and accuracy. The conventional PI Controller (PIC) has its disadvantages, including that it is time-consuming and comes with complexity in the estimation of gain values. Hence, the Cuttlefish Optimization Scheme (COS) is proposed for the online tuning of the PI gain values. The verification of performance parameters, including active power, reactive power, DC voltage balance, and Total Harmonic Distortion (THD), is effectively conducted using the COS method and subsequently compared with the conventional PIC. The suggested research is executed using the Matlab/Simulink software package.

Design and Harmonic Elimination of sinusoidal pulse width modulation (SPWM) Based Five Level Cascaded H-Bridge Multilevel Inverter for Photovoltaic System for Educational Purposes

In this modern era, the electrical power system faces a shortage of fossil fuel-based energy sources. To overcome this problem, people more focus on giving towards renewable energy sources like solar energy, wind energy, and nuclear energy sources. This also can be used to overcome global warming and reduce pollution by fossil fuels. This study used a photovoltaic (PV) array to give supply to the Multilevel Inverter (MLI) with different irradiance values, which can be used for educational purposes. The sinusoidal pulse width modulation (SPWM) method is used here to control the converter. SPWM technique is the easiest technique than the other types of pulse width modulation (PWM) technique. In this technique the switching loss is very low, therefore efficiency is high. After the simulation, the output waveforms are similar to the sinusoidal waveform for the resistive load. In this topology, after simulation, the total harmonic distortion (THD) contents were found to be less by using an LC filter. The model is simulated in MATLAB/Simulink. The analysis of output voltage waveforms is discussed with the reduced THD.

Single-phase grid-connected power control in dq synchronous reference frame with space vector modulation using FPGA

This paper presents the performance of controlling the active and reactive power of single-phase grid connected inverter by dq synchronous reference frame and space vector modulation (SVM) which is implemented by using field programmable gate array (FPGA) due to the flexibility they offer in comparison to other digital signal processors, hence it become the standard instruments for implementing various types of pulse width modulation (PWM) digital signal processors (DSPs). The SVM method has used because of its superiority in terms of harmonic distortion, switching losses and utilization of direct current (DC) bus. The synchronization is achieved by using second order generalized integrator (SOGI) due to its simple structure, certain filtering ability and frequency adaptability, in which the phase locked loop (PLL) ensures high performance for single-phase inverter. The active and reactive inverter current has been controlled and decoupled from each other and the dynamic response has been improved and became fast with proper feed-forward and decoupling grid voltage term. The system has simulated by MATLAB and the result shows robust control of injected grid current, active and reactive power control and DC link voltage control.

A Nine-Level Inverter with Adjustable Turn-Off Time for Helicopter Transient Electromagnetic Detection.

The current inverter is the core component of the helicopter transient electromagnetic (HTEM) detection system. It should meet the concerns of low loss, high power, and fast turn-OFF time. This article proposes a new circuit topology based on nine-level inverter technology to overcome the drawbacks of typical PWM (pulse width modulation) inverters, such as switching losses and harmonics. This circuit topology overcomes the shortcomings of the traditional single constant voltage clamp circuit in which the turn-OFF time is not adjustable. Using an inverter with the proposed topology is able to avoid the complex PWM control method and switching loss. In this way, the current rising edge and falling edge of this inverter are also improved effectively. The proposed inverter has adjustable turn-ON-time and turn-OFF time, which is significantly different from the conventional single-clamp inverter. Through subsequent experiments, the inverter proved to have the capability of generating trapezoidal current waveforms. Moreover, by modifying the FPGA (Field Programmable Gate Array) control program, three different turn-OFF times are achieved. The nine-level inverter has a peak current of 1.5 A with an adjustable turn-OFF time from 129 μs to 162 μs. Moreover, the switching frequency of the inverter is reduced from 10 kHz to below 100 Hz. The experimental results further demonstrate that it achieves lower switching losses and more flexible transmission. Our work in this article provides an efficient way to improve the performance of HTEM detection systems.

Solar Charger Controller Efficiency Analysis of Type Pulse Width Modulation (PWM) and Maximum Power Point Tracking (MPPT)

Solar radiation at any time can be different due to various things such as blocking of sunlight due to clouds, the intensity of the sun from sunrise to sunset, cloudiness in the rainy season, and the presence of fog in certain areas which causes different levels of solar energy. radiation that causes the output power of solar cells to vary. and not optimal. For that we need a control device that can stabilize the energy output from solar cells called Solar Charge Controller (SCC). This research was conducted to determine the value of the output power, voltage, and current of SCC type Type Pulse Width (PWM) and Maximum Power Point Tracking (MPPT), then determine the value of efficiency, and compare which type of SCC is better to use. Sampling of solar voltage and current data in the field at 10.00 – 15.00, this is because at that time the sunlight reaches its maximum intensity. The results showed that the MPPT type SCC efficiency was higher than the PWM type SCC efficiency value, namely 84.623% the MPPT type SCC efficiency compared to 80.935% PWM type SCC efficiency.
 Keywords: Solar Charge Controller, Pulse Width Modulation, Maximum Power Point Tracking

A Study on Performance and Characteristic Analysis According to the Operating Point of IPMSM Drive

This study presents the characteristics and performance of a motor at the operating point based on pulse-width modulation (PWM). PWM is used in modulating the output voltage of a three-phase inverter. The PWM technique has advantages and disadvantages depending on the system size and operating range. For example, some discontinuous pulse-width modulation (DPWM) techniques are advantageous in low-cost systems because they can reduce the number of switches. Some PWM techniques are complicated for software construction and require a lot of computation. In this paper, PWM techniques were constructed by using the offset voltage injection method. Therefore, the construction of the PWM technique is simplified by the method. In an experimental setup, an interior permanent-magnet synchronous motor (IPMSM) and a three-phase inverter were implemented to test motor control performance depending on the PWM technique. In addition, the current control characteristics and inverter efficiency were analyzed and compared depending on the speed and load of the motor. According to the results of this paper, it is possible to compare the motor and inverter control characteristics using various types of PWM rapidly. Additionally, it will help to select an appropriate PWM technique for a specific system.

Analytical Characterization of CM and DM Performance of Three-Phase Voltage-Source Inverters Under Various PWM Patterns

The need for analytical models and tools to investigate common-mode (CM) and differential-mode (DM) signals in motor drive systems is evident in previous literature, which focuses on simulations and experiments. In this article, an analytical model of CM voltage (CMV) for various pulsewidth modulation (PWM) schemes is presented as a double Fourier integral (DFI) and the DM current (DMI) is described by mathematical equations. The model is applied to different modulation schemes such as space vector PWM, two types of discontinuous PWM, and active zero state PWM (AZSPWM) for two-level and three-level multiphase inverters. The impact of these four modulation schemes on the CMV and DMI is comprehensively compared across varying modulation indices. The DFI model shows that while AZSPWM has the lowest CMV around the switching frequency, it has increased sideband CMV. However, it still yields the best total CMV reduction overall. An SiC inverter is built to experimentally validate the analytical model with a range of switching frequencies of 10-40 kHz. In this system, a high-resolution field-programmable gate array (FPGA) is used to implement the control algorithm and assess the impact of control bandwidth on CMV and DMI.

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.

Output Perfect Tracking Control for a Plant with PWM-Type Input

It is a well-established fact that an unstable zero may appear when a minimum-phase continuous-time system is discretized by a zero-order hold. Therefore, a feedforward controller cannot be obtained based on the inverse system; this is because it becomes unstable. Herein, an exact linearization method for a continuous-time system with a pulse-width modulation-type (PWM-type) input has been proposed showing that unstable zeros of the linearized discrete-time system can be moved to the stable region by altering the pulse-centers location. This enables the construction of a stable feedforward controller that achieves an output perfect tracking control. However, the current paper shows a trade-off between the stability of the stabilized zero and the maximum pulse-width. This prevents the unstable zero from moving to a high stability region, and shows some oscillation at the output of the feedforward controller. To address this, a zero-phase error filter has been introduced to reduce the oscillation. Further, a nonlinear deadbeat controller is also proposed, which can be applied to second and higher order systems. The effectiveness of the proposed methods are presented in this paper by performing simulations.

Hybrid PWM Control for Regulating the High-Speed Operation of BLDC Motors and Expanding the Current Sensing Range of DC-link Single-Shunt

This study developed a hybrid pulse width modulation (PWM) control method intended for use in a high-speed brushless dc (BLDC) motor drive system that uses DC-link single-shunt current measurement. The method is designed to regulate rapid operation and expand the current sensing range of the aforementioned system and measurement, respectively. The operating characteristics of most typical PWM methods for BLDC motors were analyzed, after which, a PWM approach suitable for high-speed operation was identified. On the basis of the selected approach, the measurable range of DC-link single-shunt current was examined mathematically to determine a PWM method that is advantageous for current sensing. The results of the two analyses were used as guidance in formulating the proposed hybrid PWM control algorithm. Finally, the PWM method put forward in this work was verified through experimentation.

DC Side Bus Voltage Control of Wind Power Grid-Connected Inverter Based on Second-Order Linear Active Disturbance Rejection Control

In order to improve the dynamic response speed and the steady-state performance of the DC side bus voltage of the wind power grid-connected inverter, a mathematical model of a typical three-phase voltage type PWM (Pulse Width Modulation, PWM) grid-connected inverter was established, and its traditional voltage-current double closed loop with proportional-integral control method was analyzed. Then a second-order linear active disturbance rejection controller that does not depend on system model information was designed to replace the traditional voltage outer loop proportional-integral controller, thus a new double closed-loop control structure was formed to control it. The frequency domain theory was used to analyze the convergence of the third-order linear extended state observer and the influence of the total disturbance on the performance of the third-order linear extended state observer. The parameter tuning scheme of the designed controller was given. Finally, the 1.5 MW direct-driven permanent magnet wind power generation system was built in the Matlab/Simulink software and the control effects of the two control modes under different working conditions are compared. The simulation results show that the control scheme designed in this paper is superior to the traditional proportional-integral controller which has good anti-interference characteristics and robustness. Especially it has a good stability effect on DC side bus voltage fluctuations.

On the Switching Frequency of Hysteresis Control in a Silicon Carbide Converter Pump-Back Test

The pump-back test is widely adopted in the industry for characterizing and qualifying high-power converters. One popular pump-back test configuration is to tie the dc links of two converters together and circulate the current through the inductor connected between the ac terminals. In this configuration, one of the converters operates in the voltage mode to generate the virtual grid and the other converter regulates the circulating current, where hysteresis control could be applied. However, the switching characteristics of hysteresis control are unique due to the pulsewidth modulation type voltage being the virtual grid. This paper contributes to analyzing the switching frequency characteristics of the hysteresis control in this pump-back test configuration. The switching frequency tracking phenomenon is revealed and reported in this paper for the first time. Theoretical analysis, simulation validation, and experimental demonstration are provided to support the major conclusions.

Approximate Discrete-Time Modeling of DC–DC Converters With Consideration of the Effects of Pulse Width Modulation

For dc–dc converters with pulsating output current, such as boost and buck–boost converters, the use of leading-edge or trailing-edge pulse width modulation (PWM) can result in distinctly different behavior. This phenomenon is not readily captured by the usual averaged model but can be predicted with a discrete-time model. However, the discrete-time model, which tracks the dynamics of state variables over a switching period, is usually more complex and less convenient to apply for the design of the feedback control. Based on the low-pass characteristics of dc–dc converters, an approximate discrete-time model is proposed in this paper, and upon transforming to the s -domain, the model results in transfer functions that can be conveniently used for deriving practical closed-loop parameters. With the proposed model, the loop gain, the input and output impedances are derived and analyzed. The effects of applying different types of PWM on the stability of a single dc–dc converter and a system of cascaded dc–dc converters are discussed. Finally, prototypes of a buck converter, a boost converter, and a cascaded system of buck and boost converters are constructed to verify the effectiveness of the approximate discrete-time model.

Torque ripple reduction PWMs for a single DC source powered dual‐inverter fed open‐end winding induction motor drive

Two new pulse width modulation (PWM) methods are proposed for a dual two-level inverter (DTLI) fed open-end winding induction motor drive for complete elimination of zero sequence voltage (ZSV), enabling the DTLI drive to be powered from a single DC power supply only. One of the PWM methods is carefully devised and uses a single inverter only to be switched at all instants of time and dwell times of that switching inverter are derived by applying a simple volt-second balance principle, for ZSV elimination. The second PWM method involves switching of both the inverters, for ZSV elimination in the DTLI. While the dwell times of first inverter are derived using the concept of ‘effective-time’, whereas dwell times of the second inverter are obtained by thoughtfully exploiting the notion of ‘phase-shift’. Additionally, torque ripple performance of the open-end winding induction motor is theoretically analysed; ripple content is quantified to compare the performance of the proposed PWM methods. Finally, a typical PWM variant that results in the least torque ripple in the induction motor is recommended. All the envisaged ZSV elimination PWM methods and its variants are simple to implement and are first analysed, simulated and experimentally verified.

A High-Precision Control for a ZVT PWM Soft-Switching Inverter to Eliminate the Dead-Time Effect

Attributing to the advantages of high efficiency, low electromagnetic interference (EMI) noise and closest to the pulse-width-modulation (PWM) converter counterpart, zero-voltage-transition (ZVT) PWM soft-switching inverters are very suitable for high-performance applications. However, the conventional control algorithms intended for high efficiency generally results in voltage distortion. Thus, this paper, for the first time, proposes a high-precision control method to eliminate the dead-time effect through controlling the auxiliary current in the auxiliary resonant snubber inverter (ARSI), which is a typical ZVT PWM inverter. The dead-time effect of ARSI is analyzed, which is distinguished from hard-switching inverters. The proposed high-precision control is introduced based on the investigation of dead-time effect. A prototype was developed to verify the effectiveness of the proposed control. The experimental results shows that the total harmonic distortion (THD) of the output current of the ARSI can be reduced compared with that of the hard-switching inverter, because the blanking delay error is eliminated. The quality of the output current and voltage can be further improved by utilizing the proposed control method.

Research and development of conversion of direct current voltage to the quasi-sinusoidal voltage with pulse-width modulation

Practically all widely used variable-frequency alternating-current electric drives with autonomous voltage inverters (AVIs) use pulse-width modulation (PWM) according to one of the following techniques: sinusoidal, space-vector, and relay. Fulfilling the relay PWM requires an analog–digital converter (ADC) with high resolution and sample rate. Vector PWM has a nonsinusoidal output voltage that causes additional losses in the motor. The main problem of a symmetrical (centered) sinusoidal PWM is underuse of a dc link. For a long time, the vector PWM method was taken to be most promising one due to the absence of this defect. In practice, this technique is applied in areas without a strong voltage criterion, for which reason it has limited use. Moreover, due to another significant problem, which is the “dead” time on the sector borders at the vector PWM, different modified methods for constructing the sinusoidal PWM have become widespread, especially in modern asynchronous motor control systems, with the development of digital microprocessor systems. To determine the quality of different types of PWMs, a complex model of an electric drive, incorporating an inverter control system that implements different algorithms of constructing the discrete PWM signals is developed. The model and the electric circuit are constructed in LabVIEW and NI Multisim, respectively. The obtained simulation data can be used to select the optimal method of controlling the AVI. The analysis that has been conducted allows one to select an optimal PFWM control strategy in terms of research results concerning electric power quality and mechanical properties.

Novel Single-Phase PWM AC–AC Converters Solving Commutation Problem Using Switching Cell Structure and Coupled Inductor

This paper presents novel single-phase pulse width modulation (PWM) ac-ac converters that can solve the commutation problem in single-phase direct PWM ac-ac converters without sensing the input voltage polarity. By using a basic switching cell structure and coupled inductors, the proposed ac-ac converters can be short- and open-circuited without damaging the switching devices. Neither lossy RC snubber nor dedicated soft commutation strategy is required in the proposed converter. By replacing the conventional phase-leg of the PWM ac-ac converters with the switching cell structure and the coupled inductor, three novel buck, boost, and buck-boost type PWM ac-ac converters are developed. Although two coupled inductors are required for the proposed converter, the input inductor of the proposed converter can be much smaller than that of the conventional PWM ac-ac converters. The volume of the magnetic components can be further reduced by increasing switching frequency of the converter because very fast recovery diodes can be selected externally. In order to verify performance and robustness of the proposed converter, a 200-W boost type prototype converter was built and tested with both mismatched gate signals and highly distorted input voltage.

Development of a Charge Controller Dedicated to the Small Wind Turbine System

In this paper, we present the development of charge and discharge controller of battery used in low power wind applications. This controller allows on the one hand protecting the battery against overcharging and deep discharge. On the other hand, it helps to protect the turbine against strong winds. It is controlled by PIC microcontroller 16F877A. This control function is performed using an algorithm that continuously compares the battery voltage to the charge and discharge thresholds, and tilting towards dissipation resistors. The control signals generated by the microcontroller are PWM (Pulse Width Modulation) type. The validation of the main functions of the controller is presented.

Simplified implementation of optimised carrier‐based PWM in three‐level inverters

Carrier-based modulation has been widely adopted since it offers some benefits compared to space-vector modulation in both two-level and in multilevel three-phase inverters, such as inherent simplicity, flexibility, reduced computational times and easy implementation on industrial DSPs. Among the numerous types of pulse width modulation (PWM) techniques, the centred PWM (CPWM) is nearly optimal modulation since it minimises the RMS of the output current harmonics. Despite optimised CPWM being easy to implement in two-level inverters, the complexity increases in the case of three-level and multilevel inverters. A straightforward and simplified procedure to implement optimised CPWM in carried-based modulation for the three-level inverter is proposed and numerically verified.

Space vector‐based three‐level discontinuous pulse‐width modulation algorithm

Discontinuous pulse-width modulation (PWM) techniques result in reduced power loss in voltage source inverters. This study presents the space vector approach to the three-level discontinuous PWM technique. The switching sequences for four basic types of discontinuous PWM and the implementation are presented. An improved discontinuous PWM algorithm is presented for low modulation index region. All these algorithms are verified experimentally and the results are presented. The performance of discontinuous PWM algorithms is compared with that of conventional space vector-based PWM algorithms.