Search Results (68)

The rapid growth of electromobility and the increasing deployment of EV chargers emphasize the importance of pulse rectifiers with built-in power factor correction (PFC) filters. The new switching power devices offer higher converter switching frequencies, which enable a decrease in nominal values of passive components, such as inductors and capacitors, and their physical dimensions. Devices like CoolMOS and GaN enable operation with low switching power, but are usually constructed for lower drain-source voltage. From this point of view, the Vienna Rectifier is a prospective type of pulse rectifier with built-in PFC because of its reduced blocking-voltage requirements for the power transistors. Nevertheless, faster switching semiconductor devices with lower switching gate charge require more precise driving circuit tuning and setup. There are many scientific papers focused on the driving setup and techniques of the power transistors applied in H-bridge topologies. The purpose of this paper is to investigate the commutation loop and the related switching phenomena of the Vienna Rectifier topology. This paper evaluates the driver setup for a CoolMOS-based Vienna Rectifier with anti-serial connection of transistors forming a bidirectional switch. The switching transients are analyzed and simulated. Subsequently, the real driver settings are evaluated on the real prototype. Full article

Some previous studies argue that under the conditions of a double line to ground fault at the point of common coupling at the inverter end, the AC grid voltage of phases A and B will decrease along with the same level while the phase C will maintain at a stable steady state and this will lead to an excess increase in the voltage level of the high voltage direct current (HVDC) link. Presented in this paper is a model that comprises the hybrid multiterminal line commutated converters and the voltage source converter HVDC system. This model was mathematically modelled and implemented on Matlab/Simulink software in order to investigate the fault behavior, with a particular emphasis on double line to ground fault at different fault resistances. The system under study consists of a fault switch timer, photovoltaic solar array, wind energy conversion system, inverter control for the voltage source converter, Inductor–capacitor–inductor (LCL) filter and PI section line. The findings of this study indicated that during the double line to ground fault at varying fault resistances, the AC grid voltage in phase A will experience a more pronounced decrease compared to phase B. In contrast, phase C will exhibit only a slight reduction in voltage at the inverter end. Similarly, at the inverter end of the hybrid system, it was observed that the AC grid currents for the affected phases, specifically phases A and B, will experience an increase. It is further discovered that phase C will maintain relatively stable condition without increasing or decreasing during a double line to ground fault event. In addition, it is noted that the HVDC link voltage will decrease while the HVDC link current will increase depending on any fault resistance values. Thus, the inferences as a result of this study are presented in this paper. Full article

This paper presents a model-based control strategy for a power factor correction system that employs a high conversion-ratio DC–DC converter. The proposed system consists of two stages. In the first stage, a full-bridge diode rectifier is connected to the grid through a passive filter to improve the quality of the injected current. Two passive AC input filters, namely L and $LCL$ configurations, are evaluated to analyze their impact on grid current quality and overall system performance. The second stage is a high-step-up DC–DC converter based on the switched-inductor technique, which provides a high voltage conversion ratio. A model-based approach is employed to derive the control design from the averaged system model. The resulting control structure consists of a current tracking loop and a voltage regulation loop. A proportional-resonant controller is used to ensure current tracking and achieve a near-unity power factor, while a proportional-integral controller regulates the output voltage. Experimental validation is carried out using a low-power laboratory-scale prototype to assess the effectiveness of the proposed approach. The results demonstrate adequate current tracking and satisfactory dynamic performance within the tested operating conditions. Full article

This paper investigates harmonic compensation for an LCL-filtered cascaded H-bridge (CHB) STATCOM operating in medium-voltage distribution networks under grid-frequency deviations and nonlinear loads. A hybrid current control strategy is proposed by combining a deadbeat (DB) inner-current loop with a Thiran all-pass filter-based frequency-adaptive repetitive controller (FARC). Weighted average inductor current (WAIC) feedback is adopted to reduce the third-order LCL filter to an equivalent first-order plant, thereby simplifying the current loop design while retaining the dominant low-frequency dynamics. The Thiran all-pass fractional delay filter is then embedded in the repetitive controller to realize a noninteger-period internal model at a fixed sampling frequency. This enables the controller to maintain harmonic compensation accuracy when the grid frequency deviates from its nominal value. A 10 kV LCL-filtered CHB STATCOM model is developed in MATLAB/Simulink, and the proposed method is compared with a conventional repetitive controller (CRC) under nominal frequency, frequency drift, nonlinear loading, harmonic load-switching conditions and grid impedance variation. Simulation results show that the proposed controller reduces the grid-current THD from 4.35% to 3.88% at 50 Hz, from 5.20% to 2.37% at 49.6 Hz, and from 6.51% to 3.56% at 50.4 Hz. In the tested frequency range of 49.5–50.5 Hz, the proposed method also maintains the power factor close to unity. These quantitative results demonstrate improved frequency robustness, harmonic suppression, and current-tracking performance compared with the CRC scheme, indicating that the proposed method can enhance STATCOM-based power quality compensation and support more reliable and efficient operation of medium-voltage distribution networks. Full article

Pure electric construction machinery (PECM) is gradually becoming the mainstream choice for industrial construction. This paper presents a new configuration of an integrated charger for PECM. The proposed configuration employs a nine-switch-converter (NSC) that can achieve charging and traction functions for the target application. In charging mode, the motor is reused as a filter inductor and the NSC is reused as a conventional three-phase PWM rectifier. Data-driven adaptive predictive control (DAPC) based on recursive least squares (RLS) is proposed to cope with the motor’s saturation problem in charging mode. This control has the advantages of excellent robustness and fast dynamic response. Although the initial parameters are derived from the system model in the first sampling cycle, the controller subsequently relies entirely on online identification, which significantly reduces the sensitivity to parameter accuracy and eliminates the need for manual tuning of controller gains. In propulsion mode, the NSC enables independent operation of the two motors. The proposed configuration improves the utilization of devices and motors, which greatly reduces the weight, volume, and cost of the charger. Finally, an experimental platform was built to verify the feasibility and validity of the proposed topology and control algorithm. Full article

Conventional multi-channel ultrasonic motor (USM) drive systems commonly adopt a one-motor–one-driver architecture, in which each drive channel requires an independent isolated power supply and inverter stage. As the number of motors increases, the system volume and structural complexity grow significantly. To address this issue, this paper proposes a shared DC-bus multi-channel drive architecture for traveling-wave USM. In the proposed scheme, multiple half-bridge power stages are connected in parallel to a common high-voltage DC-bus to achieve centralized energy supply and distributed driving. A DC-side midpoint reference network is introduced to establish an AC voltage reference under a unipolar DC supply, while an independent series matching inductor is employed in each channel to shape the half-bridge output into a quasi-sinusoidal motor-terminal voltage through resonant filtering. Based on the equivalent electrical model of the USM, a unified analytical model is established to analyze the voltage formation mechanism under shared DC-bus conditions. Time-domain simulations and experimental tests are carried out on a two-channel prototype operating at a 150 V DC-bus and a 40 kHz switching frequency. The results demonstrate stable quasi-sinusoidal output voltages, preserved phase consistency, and limited inter-channel coupling during parallel operation. Compared with conventional independent-supply solutions, the proposed architecture achieves an approximately 27% reduction in overall system volume for a three-motor configuration, demonstrating good scalability for compact multi-channel USM drive systems. Full article

Hydrogen production from water electrolysis can not only reduce greenhouse gas emissions, but also has abundant raw materials, which is one of the ideal ways to produce hydrogen from new energy. The hydrogen production power supply is the core component of the new energy electrolytic water hydrogen production device, and its characteristics have a significant impact on the efficiency and purity of hydrogen production and the service life of the electrolytic cell. In essence, the DC/DC converter provides the large current required for hydrogen production. For the converter, its input still needs the support of a DC power supply. Given the maturity and technical characteristics of new energy power generation, integrating energy storage into offshore energy systems enables stable power supply. This configuration not only mitigates energy fluctuations from renewable sources but also further reduces electrolysis costs, providing a feasible pathway for large-scale commercialization of green hydrogen production. First, this paper performs a simulation analysis on the wind–solar hybrid energy storage power generation system to demonstrate that the wind–solar–storage system can provide stable power support. It places particular emphasis on the significance of hydrogen production power supply design—this focus stems primarily from the fact that electrolyzers impose specific requirements on high operating current levels and low current ripple, which exert a direct impact on the electrolyzer’s service life, hydrogen production efficiency, and operational safety. To suppress the current ripple induced by high switching frequency and high output current, traditional approaches typically involve increasing the output inductor. However, this method substantially increases the volume and weight of the device, reduces the rate of current change, and ultimately results in a degradation of the system’s dynamic response performance. To this end, this paper focuses on developing a virtual impedance control technology, aiming to reduce the ripple amplitude while avoiding an increase in the filter inductor. Owing to constraints in current experimental conditions, this research temporarily relies on simulation data. Specifically, a programmable power supply is employed to simulate the voltage output of the wind–solar–storage hybrid system, thereby bringing the simulation as close as possible to the actual operating conditions of the wind–solar–storage hydrogen production system. The experimental results demonstrate that the proposed method can effectively suppress the ripple amplitude, maintain high operating efficiency, and ultimately meet the expected research objectives. That makes it particularly suitable as a high-quality power supply for offshore hydrogen production systems that have strict requirements on volume and weight. Full article

This article introduces a quadratic boost converter topology that has a low input current ripple compared to other quadratic boost traditional topologies. The proposed converter is inspired by the LCL filter; one of the inductors in the traditional converter is split into two inductors and a capacitor. The proposed converter has more components than its previous version, but two of its inductors are equivalent to the second inductor in the traditional quadratic boost, providing a non-increase in the size while reducing the switching ripple at the input current. These findings suggest that the proposed design is a viable alternative for applications where a quadratic gain is required while a small input current ripple is desirable. A comparative evaluation with a design showed the proposed converter reduced 20% in the stored energy of inductors and still has a reduction of more than 40% in the input current ripple. Simulation and experimental results are provided to demonstrate the principle of the proposition. Full article

With their superior switching speed, GaN high-electron-mobility transistors (HEMTs) enable high power density, reduce energy losses, and increase power efficiency in a wide range of applications, such as power electronics, due to their high breakdown voltage. GaN-HEMT devices are subject to long-term reliability due to the self-heating effect and lattice mismatch between the SiC substrate and the GaN. Depletion-mode GaN HEMTs are utilized for radio frequency applications, and this work investigates three wide-bandgap (WBG) GaN HEMT fixed-frequency oscillators with output buffers. The first GaN-on-SiC HEMT oscillator consists of an HEMT amplifier with an LC feedback network. With the supply voltage of 0.8 V, the single-ended GaN oscillator can generate a signal at 8.85 GHz, and it also supplies output power of 2.4 dBm with a buffer supply of 3.0 V. At 1 MHz frequency offset from the carrier, the phase noise is −124.8 dBc/Hz, and the figure of merit (FOM) of the oscillator is −199.8 dBc/Hz. After the previous study, the hot-carrier stressed RF performance of the GaN oscillator is studied, and the oscillator was subject to a drain supply of 8 V for a stressing step time equal to 30 min and measured at the supply voltage of 0.8 V after the step operation for performance benchmark. Stress study indicates the power oscillator with buffer is a good structure for a reliable structure by operating the oscillator core at low supply and the buffer at high supply. The second balanced oscillator can generate a differential signal. The feedback filter consists of a left-handed transmission-line LC network by cascading three unit cells. At a 1 MHz frequency offset from the carrier of 3.818 GHz, the phase noise is −131.73 dBc/Hz, and the FOM of the 2nd oscillator is −188.4 dBc/Hz. High supply voltage operation shows phase noise degradation. The third GaN cross-coupled VCO uses 8-shaped inductors. The VCO uses a pair of drain inductors to improve the Q-factor of the LC tank, and it uses 8-shaped inductors for magnetic coupling noise suppression. At the VCO-core supply of 1.3 V and high buffer supply, the FOM at 6.397 GHz is −190.09 dBc/Hz. This work enhances the design techniques for reliable GaN HEMT oscillators and knowledge to design high-performance circuits. Full article

Digital control in UPS systems is currently the only reasonable way of controlling a voltage source inverter (VSI). The control frequency range is restricted to up to about 1 kHz owing to the output low-pass LC filter, which should also maintain the output voltage during one switching period for the step unload. The measurement channels in the low-pass frequency range can be modeled as delays equal to some switching periods. A reasonably high (about 50 kHz) switching frequency minimizes the delays of the measurement channels. Two control systems will be compared—the pure discrete control, in this case a one-sample-ahead preview deadbeat control (OSAP), and a discretized passivity-based control (PBC). The OSAP control is easy to realize, is very fast, and enables one to obtain a steady state in a restricted number of steps after disturbance. However, the single-input single-output deadbeat control version is useless because it depends very strongly on the parameters of the inverter. The multi-input single-output OSAP (MISO-OSAP) control is directly based on discrete state equations (we treat the output voltage, output current, and inductor current as the measured state variables) and works perfectly for the nonlinear rectifier RC load (PF = 0.7) in a system without delay. The version of this with a linear prediction of state variables by means of a full-order state Luenberger observer (MISO-OSAP-LO) will be used in systems with different delays and compared with the discretized MISO passivity-based control without prediction for relatively high switching frequency (about 50 kHz). The aim and the novelty of the paper are in enabling a choice between one of these control systems for high switching frequency VSI with delays in the measurement channels. Full article

In order to upgrade the ability of the traditional flyback converter to transfer energy to the load, a dual-flyback converter with two active clamping circuits is added, using the same clamping capacitor to recover the leakage inductance energy. Furthermore, no additional resonant inductor is needed, and both the switches have zero voltage switching (ZVS) to reduce the switching loss. In addition, full-wave rectification is used on the secondary side to decrease the output voltage ripple frequency, which makes it easy to design the output filter. Full article

Pulse frequency modulation (PFM) is widely used in LLC resonant converters. However, in wide voltage applications, the switching frequency range is very wide, which affects the performance of magnetic components and filters. In order to achieve wide voltage gain in a narrow frequency range, this paper proposes a unified inductor type based linear resonant hybrid converter (UITBLRHC). The resonant inductor and excitation inductor are unified, and the resonant tank with equal inductance ratio is achieved. Hence, the output voltage can be adjusted within a very narrow frequency range. In addition, the parameters and operating modes of the two inductors are exactly the same. Therefore, the types of inductors can be reduced, and the magnetic flux and heat distribution between the two inductors are more uniform. Finally, an 800 W prototype was built. The proposed solution can achieve twice the voltage gain within a frequency range of 1.25 times. The experimental results prove the reliability and validity. Full article

The Shunt Active Filter (SAF) is an effective solution for mitigating electrical perturbations in power networks. SAFs usually consist of a voltage source inverter (VSI) with lossy transistors and bulky inductors. In this context, this article proposes analytical models to evaluate the losses and efficiency of a SAF. The models include conduction and switching losses in the transistors and diodes and are valid for both IGBT and SiC MOSFET transistors. The methodology consists of analysing the current waveform to separate the portion flowing through the transistor or diode. IGBT and SiC MOSFET are compared in two cases: firstly, the classic SAF operation with harmonic and reactive power compensation and, secondly, in the case of power injection by a photovoltaic panel or batteries, in addition to the classic SAF operation. The results are validated with real manufacturer data. A step-by-step comparison shows a good accuracy of the model. Therefore, the developed methodology is useful for a SAF designer to select relevant components for the converter and to estimate the efficiency of the system accurately and quickly. Full article

A grid-connected converter is the interface between renewable energy power generation systems, such as solar power generation, wind power, hydropower, etc., and the power grid, responsible for the stable and efficient transmission of electric energy generated by renewable energy power generation systems to the grid. In order to realize local access for distributed photovoltaic power generation devices and energy storage devices, a composite three-port converter has the advantages of small size, low cost and high power density compared with a combined three-port converter. In view of the current problems of the existing compound three-port (AC/DC/DC) converters, such as DC and AC circulating current in current composite three-port converters and the harmonic control problem, the proposed compound three-port topology consists of a full-bridge inverter with six switching tubes, a zigzag transformer, two sets of filter inductors and two filter capacitors. Among them, the power frequency transformer adopts the zigzag connection method, which can effectively restrain the AC circulation and eliminate the DC magnetic flux of the iron core while introducing the third port. Firstly, the principle of AC/DC and DC/DC power conversion in the composite three-port topology is analyzed, which has higher efficiency than other topologies. Secondly, the topology control strategy is analyzed, and a two-loop hybrid current control method with improved current loop is proposed. When the DC-side voltage fluctuates, the DC offset of the battery can effectively improve the stability of the network side. Through the MATLAB/Simulink simulation experiment platform, the high efficiency of energy conversion and stable grid-connected operation characteristics are verified. Finally, the experiment of integrating into the power grid was carried out. Experiments were used to verify the effectiveness and feasibility of the proposed topology and strategy. The experimental results show that Total Harmonic Distortion (THD) can be controlled below 3%. Full article

Half-bridge converter series microgrid (HBCS-MG) is susceptible to a variety of uncertainties and disturbances during operation, and therefore, the use of the traditional integer-order models cannot accurately reflect the effects of environmental variations on internal components of the off-grid system, such as converters, filters, and loads, including factors like time delays, memory effects, and multi-scale coupling. The fractional-order control method is better equipped to deal with these disturbances, thereby enhancing the robustness and stability of the system. In the off-grid state, a fractional-order PI (FOPI) controller is employed for double-closed-loop control, and the load voltage feedforward control is utilized to offset the impact of load voltage fluctuations on the system. A new simplified equivalent circuit calculation method for the fractional-order inductor is proposed, and a complete fractional mathematical model of the system in the dq rotating coordinate system is established to obtain the transfer function between the load voltage and the input voltage. Furthermore, the impact of the fractional-order variation of the FOPI controllers and the fractional elements on system performance in the frequency domain and time domain is described in detail. The simulation results are compared with the theoretical analysis to demonstrate the accuracy of the mathematical model. The overshoot of the load voltage at the switching instant of 0.7 s is reduced by 4.2% compared with the integer-order PI controller, which proves that the fractional-order controller can improve the system control accuracy. Full article