Pulse Width Modulation Technology Research Articles

Performance Characteristics of a Newly Developed Asymmetric Seven-Level Inverter Utilizing Various Hybrid Pulse Width Modulation Strategies

This study unveils a notable breakthrough in inverter technology, holding promise for substantial improvements in voltage quality and the attenuation of harmonic distortions within power systems. This study concentrates on the design and implementation of a novel Seven-Level Asymmetric Inverter (NSLAI) by incorporating various hybrid Pulse Width Modulation (PWM) techniques. The primary goal is to improve the output voltage magnitude while decreasing the Total harmonics compared to conventional PWM methods. The investigation introduces a novel Seven-Level Asymmetric Inverter (NSLAI) with innovative Hybrid Pulse Width Modulation (PWM) strategy. The purpose of this study is to investigate the distinct features of a recently developed asymmetric seven-level inverter, with a focus on exploring its characteristics through the implementation of diverse hybrid pulse width modulation strategies. Hybrid PWM methodology intricately centers on enhancing voltage quality and achieving better harmonious spectral characteristics. The gate signal producing approach for this suggested PWM technology incorporates a hybrid PWM methodology that combines trapezoidal and sinusoidal waveforms, as well as a standard triangular carrier signal enabling NSLAI. The hybrid version of PWM practices is deliberately used to generate switching signals for the NSLAI. An intensive evaluation of numerous indicators of effectiveness across multiple modulation indexes leads in the demonstrating of quantitative findings that compare the unique Hybrid PWM practice with established PWM tactics. Notably, the hybrid reference Carrier Overlapping strategy has emerged as a leading approach surpassing conventional pulse width modulation techniques. It achieves a significantly higher fundamental Root Mean Square voltage output and remarkably lower percentage of Total Harmonic Distortion values compared to all within the hybrid reference Variable Frequency strategy. The principal analytical tool used in the modeling investigation is MATLAB-SIMULINK. This study marks a watershed moment in the development of inverters, claiming significant improvements in battery power quality and distortion caused by harmonics avoidance across power systems, as evidenced by extensive simulation and prototype-based discoveries.

Development of an energy-saving PWM driving method for precision pesticide application using adjustable frequency and characterization of spray

Precise pesticide application is mainly to control the solenoid valve by pulse width modulation (PWM). However, as the number of solenoid valves increases, power consumption and heat generation become significant challenges that impact values the efficiency and lifetime. In this study, an automated pressure monitoring system was constructed and an energy-saving PWM driving method was developed that uses different frequency drive signals during different stages of the solenoid valve operation. The parameters such as power consumption, coil surface temperature rise, opening and closing delays, rise and fall times, activation time, and spray flow characteristics were tested and evaluated. The results showed that this method can significantly reduce the holding current of the solenoid valves, resulting in energy savings of up to 92% and effectively reducing the surface temperature rise. Furthermore, the pattern between flowrate and opening/closing delays was established, with an RMSE of 1.96% in flowrate prediction based on activation time. The developed energy-saving driving method enhances the application potential while the established flowrate model provides valuable insights for precise pesticide application based on PWM technology.

Research on Grid-Connected Control Strategy of Photovoltaic (PV) Energy Storage Based on Constant Power Operation

In order to effectively mitigate the issue of frequent fluctuations in the output power of a PV system, this paper proposes a working mode for PV and energy storage battery integration. To address maximum power point tracking of PV cells, a fuzzy control-based tracking strategy is adopted. The principles and corresponding mathematical models are analyzed for the three-phase voltage PWM converter and bidirectional DC/DC converter, while feedforward decoupling double closed loop, constant power (PQ), and constant voltage charge/discharge control strategies are proposed. Space vector pulse width modulation (SVPWM) technology is utilized to generate power switching tube driver signals. Finally, a simulation model is developed in MATLAB/Simulink for system analysis. The results demonstrate that the proposed method enables constant grid-connected power generation and constant voltage charging of the energy storage battery when the PV cell’s power generation exceeds that of the grid. When insufficient solar power generation occurs, both the PV system and energy storage battery work together to achieve constant grid-connected power.

High-performance pulse light stable perovskite indoor photovoltaics

Perovskite solar cells offer great potential as a sustainable power source for distributed electronic devices that operate indoors. However, the impact of advanced lighting technology, especially the widely used pulse width modulation (PWM) technology, on perovskite photovoltaics has been ignored. Herein, for the first time in photovoltaics, we find that the light impact emitted by the PWM lighting system caused dynamic strain in perovskite thin films, induced phase separation, and accelerated the generation of metallic lead (Pb0) defects, leading to irreversible degradation of the cell performance after 27 h (T80). To address this issue, formamidinium triiodide (FAI3) is chosen to treat the surface of the perovskite and release residual stress, resulting in reduced lattice deformation during dynamic strain processes. Meanwhile, it suppresses harmful Pb0 defects and reduces Voc loss at low light intensity. The champion device achieves impressive power conversion efficiency (PCE) of 35.14% and retains 99.5% of the initial PCE after continuous strobe light soaking for 2160 h.

The TSM-net: a new strategy for insulated bearings intelligent faults diagnosis

With the development of power semiconductor devices, pulse width modulation technology is widely used in high-power frequency conversion control motors, which significantly improves the dynamic performance of variable-speed drive system equipment. However, the high-frequency shaft voltage generated during the drive process acts on the bearing to generate high-frequency current. The damage caused by the shaft current sharply shortens the fatigue wear process of the bearing, which in turn leads to premature failure of the bearing. A high insulating ceramic coating is prepared on the outer surface and side face of the inner and outer rings of the bearing by plasma spraying. That is, an insulating protective film is formed on the outer surface of the bearing, which can effectively isolate or reduce the bearing current, prevent the occurrence of electric erosion, and prolong the service life of the variable speed drive system equipment. However, the vibration excitation generated by the variable-speed drive system equipment will cause cracks or fatigue damage to the insulating bearing, resulting in a very complex fault mechanism of the vibration signal. The fault signal characterization lacks a professional signal analysis method, especially the high-reliability, high-precision and long-life high-performance insulating bearing. There is no qualitative formula or characteristic index to explain its failure. To fill this research gap, a new strategy for optimizing the temporal information fusion model and introducing the self-attention mechanism is innovatively developed, and it is named TSM-Net model, and the first attempt is made to realize intelligent identification of insulated bearing faults. Specifically, a multi-channel insulated bearing time information fusion diagnostic model is designed, and the coarse-grained characteristics with timing law are extracted from the measured insulated bearing fault data. Then, the self-attention mechanism is introduced into the designed insulated bearing time information fusion diagnostic model to optimize, and the weight coefficient is continuously updated to calculate the correlation weight between the insulated bearing fault data and the data, so that the final decision of the TSM-Net model is more focused, so as to improve the diagnostic accuracy. Finally, comparing the proposed TSM-Net model with the current five advanced methods, it is found that the proposed TSM-Net model has good diagnostic accuracy for rail transit motor insulated bearing faults, which verifies the effectiveness and superiority of the strategy, and provides a new way for the fault diagnosis of insulated bearings of high-power inverter control motors.

Dual Random Noise Suppression Strategy for Permanent Magnet Synchronous Motor Based on Random Pulse Width Modulation and Random High-frequency Injection Method

This study proposes an innovative dual control strategy to tackle the challenge of electromagnetic noise in the sensorless low-speed operation of Permanent Magnet Synchronous Motors (PMSM). The strategy combines random Pulse Width Modulation (PWM) technology with a stochastic high-frequency injection approach. By incorporating two distinct randomized frequency switching techniques into the high-frequency injection circuit, the method integrates two-state Markov chains into both PWM technology and the random high-frequency injection method. Subsequently, a mathematical model for signal processing is developed, and extensive simulation and experimental verification are conducted. The experimental findings affirm the effectiveness of this approach in effectively mitigating electromagnetic noise while ensuring accurate location estimation within an acceptable range.

Current oscillation elimination for the helicopter transient electromagnetic inverter based on pole configuration

In a helicopter transient electromagnetic system, the quality of the transmitting-current waveform will affect the geological exploration effect. In this paper, a helicopter TEM inverter, based on a single-clamp source and pulse width modulation technology, is designed and analyzed. Besides, it finds that there will be current oscillation in the early measuring stage. For this problem, first, the factors that cause the current oscillation are analyzed. Then, it is proposed to apply the RC snubber to eliminate this current oscillation. Since the imaginary part of the pole is the essence of oscillation, configuring the pole can eliminate the current oscillation. By establishing the early measuring stage system model, the characteristic equation of the load current with the snubber circuit is deduced. Next, the characteristic equation is solved by the exhaustive method and the root locus method to obtain the parametric region that eliminates the oscillation. Finally, through simulation and experimental verification, the proposed snubber circuit design method can be used to eliminate the early measuring stage current oscillation. Compared to the method of switching into the damping circuit, it can achieve the same performance, more important is that there is no switching action and it is easy to achieve.

Intelligent Table Lamp Based on Single Chip Microcomputer

At present, modern smart home is increasingly favored by people, and the functions of intelligent desk lamps become diversified with the demand updating. In the process of using desk lamps, poor sitting posture or overuse of eyes may cause vision loss and physical pain. Therefore, it is of great theoretical significance and practical value to actively explore and develop an intelligent desk lamp with low cost and functions of automatic dimming, sitting posture correction, reminder of rest, energy conservation and environmental protection. In the intelligent desk lamp designed in this paper, STC89C51 microcontroller is used as the core controller, BH1750 light sensor module is used to detect the current ambient light intensity, and the pulse width modulation (PWM) technology is used to control the brightness of the desk lamp for TB6612 motor drive. The infrared probe module is used for personnel detection. When the infrared probe module detects that someone is approaching, the desk lamp will be automatically turned on through the relay module. When no one is detected, the microcontroller controls the relay to automatically turn off the desk lamp and power off. The intelligent desk lamp is very convenient to use. It can not only save electric energy effectively, but also solve the problem of touching the lamp in the dark and the potential safety hazard for people by automatically switching on and off the lamp. It has good application value and market prospects.

Design and analysis of a pulsed coil power supply for the DIII-D tokamak

This paper presents the design of the coil power supply system which provides a pulsed current of ±16 kA for several coils within the DIII-D Tokamak. The coil power supply system consists of 6 power supply modules and a master module controller. Each power supply module would be designed to produce ±450 VDC and ±2.66 kA (nominal) in all 4 quadrants, and 12 times carrier phase shifting PWM (Pulse Width Modulation) technology was adopted to satisfy the fast response and low ripple content of the power supply system. Meanwhile, the mathematical model of the power supply system was established to analyze the dynamic relationship between the system input and output variables, the transfer function was optimized by compensation circuit to increase the stability of the system. At last, the simulation and theoretical analysis had been completed to verify the stability and fast response of the coil power supply system.

Frequency Domain Electromagnetic System Based on Unmanned Aerial Vehicles Platform for Detecting Shallow Subsurface Targets

Due to the advantages of being nondestructive, rapid, and convenient, the electromagnetic detection method has attracted growing interest in the field of shallow subsurface detection. With the rapid development of unmanned aerial vehicle (UAV) technology, the use of the UAV platform for measurement can not only improve work efficiency but also avoid the significant losses that may be caused by humans working in dangerous areas. Therefore, we propose a broadband frequency domain electromagnetic system AFEM-3 based on a UAV platform for shallow subsurface targets detection (within less than 2 m). The sensor head adopts a concentric planar coil structure with a high spatial resolution, and a bucking coil connected in reverse series with the transmitting coil is used to suppress the primary field at the receiving coil. We designed a transmitting module based on unipolar frequency multiplication sinusoidal pulse width modulation technology that can generate multi-frequency arbitrary combination transmitting waveforms with low total harmonic distortion. It can also be matched to a variety of different transmitter coils by using the same hardware circuit. In addition, the global navigation satellite system and inertial measurement unit are integrated on the sensor head. The measurement response value, position, and attitude information can be displayed in real-time through the host computer. Through the static experiment of a standard coil, we verified the consistency between the AFEM-3 system with the theory. The performance of the system was evaluated through field experiments. The experimental results show that the system can effectively detect multiple metal targets in shallow subsurface areas. For different metal targets, the AFEM-3 system can provide obvious frequency domain characteristics.

Research on Pressure Control of an Electro-Hydraulic Servo System Based on Sliding-Mode Variable-Structure Direct Torque Control

Taking a direct-drive volume control (DDVC) electro-hydraulic servo system as the research object and aiming at the problems of the servo motor torque fluctuation, high-precision system pressure control, and dynamic response of the system, based on traditional motor direct torque control (DTC), a motor direct torque control method based on a sliding-mode variable structure is proposed to control the system pressure. The motor torque loop is part of the inner control loop and has a rapid dynamic response speed, resulting in higher pressure control accuracy. A nonlinear mathematical model was established for the DDVC electro-hydraulic servo system. The switch meter hysteresis controller in the traditional DTC system was replaced with space vector pulse-width modulation technology. Then, the PID control module in space vector modulation technology was replaced with high-order sliding-mode variable-structure control. Through the coupling relationship between the electric machine and the constant-displacement pump, the pressure can be controlled with high precision using motor torque control. Finally, using the MATLAB/Simulink simulation platform and the DDVC electro-hydraulic servo system simulation model, the proposed theoretical approach to torque control was verified on the basis of simulations and experiments, and the performance with regard to pressure control in the hydraulic system was observed. The simulation and experimental results show that the designed torque control is able to effectively reduce the motor torque fluctuation and improve the dynamic response characteristics of the system. The system pressure control is superior to traditional pressure control methods based on speed regulation, and it has higher control accuracy and a better dynamic response.

Error Self-Calibration of Phase Current Reconstruction Based on Random Pulsewidth Modulation

Three-phase current is the cornerstone parameter in vector control. Restricted by minimum sampling time of the traditional space vector pulsewidth modulation (PWM), the problem of immeasurable areas (IAs) exists in one dc bus current sensor (ODBCS) three-phase current reconstruction. In addition, affected by actual conditions such as temperature drift, aging, and noise, the problem of offset error (OE) in the three-phase current sampling path is the essential factor that restricts the sampling accuracy. This article is the first to investigate the influence of IAs and OE of ODBCS on the reconstructed current. An error self-calibration (ESC) random PWM reconstruction strategy is proposed, which is self-detection and self-calibration of current OE accomplished by dual sampling of the complementary nonzero vector dynamic current. The proposed ESC of phase current reconstruction based on random PWM does not require the insertion of redundant voltage vectors and major computation and is not limited to a particular PWM technology. The experimental results verify the accuracy and practicability of the proposed method.

Performance of a vector controlled PMSM drive based on proportional–resonance control under single-phase open circuit fault

In this paper, a vector controlled PMSM drive based on a proportional–resonance controller (PR) under open circuit fault (OCF) is proposed. The PR controller is used to generate the stator voltages. While the field-oriented control (FOC) approach has been implemented using the pulse width modulation (PWM) technology. The simulation is built using MATLAB/ Simulink. Hardware experiments were performed, and the results captured using dSPACE DS1104. The behaviour of the PMSM is studied under three operations: healthy, faulty, and post-fault operation. Moreover, the speed control of the PMSM under the three operations has been presented. The simulation and the experimental results show a fast dynamic response with some ripple in the response of speed and torque during the healthy and post-fault operations. On the other hand, during the OCF, the ripple in the torque and speed response increases. However, the proposed method proves its efficacy by keeping the motor speed nearly at the input reference speed as well as guaranteeing the continued operation of the PMSM with good steady-state and dynamic performance.

Principles, design and implementation of a direct AC-to-AC power converter-Regulated electronic transformer.

In the last three decades, the energy conversion market has been dominated by switching power converters due to reduction of size and cost of electronic components. This market includes four types of conversion: DC-DC, DC-AC, AC-DC, and AC-AC. While the first three types are applied directly in a single conversion, the AC-AC converter is comprised of two serial converters leading to an AC-DC-AC conversion. This article introduces, for the first time, a real direct single-stage AC-AC conversion electronic transformer. The single stage AC-AC converter is fabricated using a unique high efficiency topology, combined with the advantages of dual-stage power-quality protection. This single-stage AC-AC regulated electronic transformer is stabilized, controlled, protected, and can lock onto any line voltage (110 or 220V) with a frequency of 45-65Hz. Stabilization is achieved by fast pulse-width modulation technology, applied by two-way fast solid-state switches. The transformer is controlled by a 150MHz digital signal processor and is fully protected against overcurrent and output short circuits. Our first stage transformer is a single-phase device with 5 kW power with an efficiency of better than 97% with one-tenth of the weight and volume of present conventional electromechanical transformers.

An inductor design method based on multi-objective optimized algorithm for LCL-type shunt active power filter

The application of pulse width modulation (PWM) technology will produce a high-frequency switching ripple. Generally, it is considered to filter it with an LCL filter to ensure the compensation performance of the shunt active power filter. According to the system requirements for ripple current suppression and maximum current tracking capability, this paper first optimizes the design of the filter inductance in the LCL. Then, aiming at the shortcomings of the traditional inductor design process that is complicated and cumbersome, with repetitiveness and difficulty to obtain reliable analytical solutions, a 4-dimensional visualization based multi-objective optimized algorithm is proposed, and the ternary function expression between each design goal and known independent variables is first derived and established. And then, through the visual programming of the 4-dimensional data field, the optimal solution set that meets the multi-objective design requirements is directly given, which is intuitive, clear, simple, and practical. Finally, according to the algorithm results, the corresponding inductance was wound and applied to a 50kVA three-phase four-wire active power filter prototype. The experimental results verified the feasibility and effectiveness of the proposed design method.

Current Sensor Fault-Tolerant Control for Five-Phase PMSM Drives Based on Third-Harmonic Space

According to the different forms of back electromotive force, five-phase permanent-magnet synchronous motors (FPMSMs) can be divided into two types: sinusoidal FPMSMs (SFPMSMs) and trapezoidal FPMSMs (TFPMSMs). In field-oriented-controlled FPMSM drives, current sensors may malfunction in harsh working environments. In this article, two current sensor fault-tolerant control (FTC) strategies based on third-harmonic space, respectively, corresponding to SFPMSMs and TFPMSMs are proposed. Different from three-phase motor, the decoupled model of five-phase motor contains two orthogonal subspaces. The key to both strategies is that the third-harmonic space currents are controlled at zero when current sensors malfunction. Thus, the faulty phase current can be estimated with other phase currents by using the constraint equations of current transformation. For SFPMSMs, vector control and sinusoidal pulsewidth modulation technology are used to control the third-harmonic space currents to zero. For TFPMSMs, offset axis transformation and resonant observer are adopted for third-harmonic space current estimation and the third-harmonic space currents are controlled to zero by using the estimated values as feedback of vector control. The experimental results demonstrate that the robustness of both current sensor FTC systems is well performed in the whole speed range.

Glossary of pre-settings given by laser companies: no consensus!

Since the construction of the first laser, many companies around the world have contributed to the development of new lasers technologies. To be user-friendly, some companies have developed a pre-setting mode in their laser devices. We aimed to review and compare all laser companies' pre-settings (PS) already established in the market. An online search of holmium:YAG (Ho:YAG) and thulium fiber laser (TFL) devices was carried out. Manual and PS mode, pulse width and pulse modulation technology data were collected. The PS parameters were collected directly from the brochure devices or by asking the companies consulting agents. Thirty-nine laser devices were analyzed (33 Ho:YAG and 6 TFL). The power range varies from 15 to 152W and 35W to 60W for Ho:YAG and TFL, respectively. PS are present in 66% of Ho:YAG lasers and the 33% of TFL. Long-pulse modes can be modified in 12 Ho:YAG and 1 TFL lasers. The median (IQR) PS for dusting stones with Ho:YAG laser is 0.4J (0.2-1), 21.5Hz (5-120), and 10W (1.5-28) for energy, frequency and power, respectively; for Ho:YAG fragmentation is 0.8J (0.3-5), 10 (3-15) Hz and 5 (1.5-50) W for energy, frequency, and power, respectively; and for popcorn is 0.8J (0.4-1.2), 10Hz (6-15) and 5W (4-18) for energy, frequency, and power, respectively. Dusting and fragmentation mode of Rocamed MH01 and EMS LaserClast 35 are programmed according to the stone type. Most of these settings do not depend on the size of the fiber being used nor the location and type of stone. For TFL, the pre-sets are divided in bladder stone, dusting, fine dusting, fragmentation, and ureteral stone. There is a huge variability regarding pre-sets offered by companies because there is no consensus. Pre-sets should provide a range to work efficacy and safety.

Performance Enhancement of Speed Control for Induction Motor Using Dolphin Algorithm

The induction motor is renowned as one of the most motors commonly used in an industry where rapid response and high control precision are needed for a wide range of speeds. In this paper, a field oriented control method (FOCM) has been used to obtain a higher control efficiency by dividing the stator current into torque and field control components, including the space vector pulse width modulation (SV-PWM) technology. FOCM also reduces the harmonics of the inverter output signal and allows the best use of DC voltage. This paper aims to enhance the speed response during a sudden change in load torque or reference speed. The Dolphin Algorithm (DA) is used to find the best parameters of the control circuit in both the current and voltage controllers of the FOCM to improve the motor speed response using two objective functions which are Mean Average Error (MAE) and Mean Error (ME). Simulation results for dolphin-PI controllers show the trial superiority by noting PI controllers error and decrease the delay time during the state change.

Development of the Magnet Coil Power Supply for Fishtail Divertor on EAST

Fishtail divertor (FTD), a new divertor concept, is a significant research object of Experimental Advanced Superconducting Tokamak (EAST) tokamak divertor system. In order to meet the requirement of sinusoidal current precision and variable frequency, the combination of inductance and capacitance ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> ) series resonance theory and high-frequency pulsewidth modulation (PWM) technology is put forward. A sine wave power supply with multifrequency points (1–3800 Hz) and current up to 8000 A is developed. The FTD power supply (PS) adopts dc switching power technology, sinusoidal PWM (SPWM) technology, and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> series resonance theory. The operating points of output current include 10–20 Hz at 8000 A, 30–110 Hz at 5000 A, and 1300–3800 Hz at 2400 A. The electromagnetic environment in the device is complex and arguable. The output current accuracy can reach 5% by the current feedback and frequency feedback control strategy. The test results demonstrate that the FTD PS can meet the system requirements, and it has strong reference significance, which can provide reference for the design of other divertor PS.

A Design Method of the Transmitting Waveform of Electromagnetic Sounding Based on Selective Harmonic Elimination

The exploration target at different depths through the ground-airborne frequency domain electromagnetic method (GAFDEM) is detected by transmitting waveforms at different frequencies. When taking these different depths into detail, arbitrarily distributed frequencies are needed. However, the current transmitting waveforms are mostly in a fixed frequency ratio or frequency difference, which fails to meet the requirements of exploration accuracy and efficiency at the same time. Therefore, as a solution to this problem, this paper proposes a transmitting waveform design method based on selective harmonic eliminated pulse width modulation (SHEPWM) technology. In the SHEPWM method, three transmitting waveforms with the desired spectrum are obtained by directly controlling the switching angles of a binary sequence with an artificial neural network algorithm. Firstly, our study puts forward the basic theories and principles of the full-periodic asymmetric SHEPWM waveform. Secondly, the study, through simulation, realizes the pseudorandom, depth-focused, and layer-identification waveform with different detection depths. Finally, the application of the proposed SHEPWM waveform to the geological survey in Kaili City, Guizhou Province, proves the correctness and feasibility of this proposed method.