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This study aims to regarding the application of traditional pulse frequency modulation control full-bridge LLC resonant converters in wide output voltage fields such as on-board chargers, there are issues with wide frequency adjustment ranges and low conversion efficiency.

To address these issues, this paper proposes a fixed-frequency pulse width modulation (PWM) control strategy for a full-bridge LLC resonant converter, which adjusts the gain by adjusting the duty cycle of the switches. In the full-bridge LLC converter, the two switches of the lower bridge arm are controlled by a fixed-frequency and fixed duty cycle, with their switching frequency equal to the resonant frequency, whereas the two switches of the upper bridge arm are controlled by a fixed-frequency PWM to adjust the output voltage. The operation modes of the converter are analyzed in detail, and a mathematical model of the converter is established. The gain characteristics of the converter under the fixed-frequency PWM control strategy are deeply analyzed, and the conditions for implementing zero-voltage switching (ZVS) soft switching in the converter are also analyzed in detail. The use of fixed-frequency PWM control simplifies the design of resonant parameters, and the fixed-frequency control is conducive to the design of magnetic components.

According to the fixed-frequency PWM control strategy proposed in this paper, the correctness of the control strategy is verified through simulation and the development and testing of a 500-W experimental prototype. Test results show that the primary side switches of the converter achieve ZVS and the secondary side rectifier diodes achieve zero-current switching, effectively reducing the switching losses of the converter. In addition, the control strategy reduces the reactive circulating current of the converter, and the peak efficiency of the experimental prototype can reach 95.2%.

The feasibility of the fixed-frequency PWM control strategy was verified through experiments, which has significant implications for improving the efficiency of the converter and simplifying the design of resonant parameters and magnetic components in wide output voltage fields such as on-board chargers.

Brand-name pharmaceutical companies have engaged in a variety of business conduct that has increased price. One of these activities involves “product hopping,” or brand switches from one version of a drug to another. The antitrust analysis of product hopping implicates antitrust law, patent law, the Hatch–Waxman Act, and state drug product selection laws, as well as uniquely complicated markets characterized by buyers different from decision makers. As a result, courts have offered inconsistent approaches to product hopping.

In this chapter, we offer a framework that courts and government enforcers can employ to analyze product hopping. The framework is the first to incorporate the characteristics of the pharmaceutical industry. It defines a “product hop” to include instances in which the manufacturer (1) reformulates the product to make the generic nonsubstitutable and (2) encourages doctors to write prescriptions for the reformulated rather than the original product.

When the conduct meets both requirements, our framework offers two stages of analysis. First, we propose two safe harbors to ensure that the vast majority of reformulations will not face antitrust review. Second, the framework examines whether the hop passes the “no-economic-sense” test, determining if the behavior would make economic sense if the hop did not have the effect of impairing generic competition. Showing just how far the courts have veered from justified economic analysis, the test would recommend a different analysis than that used in each of the five product-hopping cases that have been litigated to date, and a different outcome in two of them.

Intelligent control for unidentified systems with unstable equilibriums is not always a proper control strategy, which results in inferior performance in many cases. Because of the existing trial and error manner of the procedure in former duration of learning, this exploration for finding the appropriate control signals can lead to instability. However, the recent proposed emotional controllers are capable of learning swiftly; the use of these controllers is not an efficient solution for the mentioned instability problems. Therefore, a solution is needed to evade the instability in preliminary phase of learning. The purpose of this paper is to propose a novel approach for controlling unstable systems or systems with unstable equilibrium by model free controllers.

An existing controller (model‐based controller) with limited performance is used as a mentor for the emotional learning controller in the first step. This learning phase prepares the controller to control the plant as well as mentor, while it prevents any instability. When the emotional controller can imitate the behavior of model based one properly, the employed controller is gently switched from model based one to an emotional controller using a fuzzy inference system (FIS). Also, the emotional stress is softly switched from the mentor‐imitator output difference to the combination of the objectives. In this paper, the emotional stresses are generated once by using a nonlinear combination of objectives and once by employing different stresses to a FIS which attentionally modulated the stresses, and makes a subset of these objectives salient regarding the contemporary situation.

The proposed model free controller is employed to control an inverted pendulum system and an oscillator with unstable equilibrium. It is noticeable that the proposed controller is a model free one, and does not use any knowledge about the plant. The experimental results on two benchmarks show the superiority of proposed imitative and emotional controller with fuzzy stress generation mechanism in comparison with model based originally supplied controllers and emotional controller with nonlinear stress generation unit – in control of pendulum system – in all operating conditions.

There are two test beds for evaluating the proposed model free controller performance which are discussed in this paper: a laboratorial inverted pendulum system, which is a well‐known system with unstable equilibrium, and Chua's circuit, which is an oscillator with two stable and one unstable equilibrium point. The results show that the proposed controller with the mentioned strategy can control the systems with satisfactory performance.

In this paper, a novel approach for controlling unstable systems or systems with unstable equilibrium by model free controllers is proposed. This approach is based on imitative learning in preliminary phase of learning and soft switching to an interactive emotional learning. Moreover, FISs are used to model the linguistic knowledge of the ascendancy and situated importance of the objectives. These FISs are used to attentionally modulate the stress signals for the emotional controller. The results of proposed strategy on two benchmarks reveal the efficacy of this strategy of model free control.

This paper aims to overcome the limitations of low efficiency, low power density and strong electromagnetic interference (EMI) of the existing pulsed melt inert gas (MIG) welding power supply. So a novel and simplified implementation of digital high-power pulsed MIG welding power supply with LLC resonant converter is proposed in this work.

A simple parallel full-bridge LLC resonant converter structure is used to design the digital power supply with high welding current, low arc voltage, high open-circuit voltage and a wide range of arc loads, by effectively exploiting the variable load and high-power applications of LLC resonant converter.

The efficiency of each converter can reach up to 92.3%, under the rated operating condition. Notably, with proposed scheme, a short-circuit current mutation of 300 A can stabilize at 60 A within 8 ms. Furthermore, the pulsed MIG welding test shows that a stable welding process with 280 A peak current can be realized and a well-formed weld bead can be obtained, thereby verifying the feasibility of LLC resonant converter for pulsed MIG welding power supply.

The high efficiency, high power density and weak EMI of LLC resonant converter are conducive to the further optimization of pulsed MIG welding power supply. Consequently, a high performance welding power supply is implemented by taking adequate advantages of LLC resonant converter, which can provide equipment support for exploring better pulsed MIG welding processes.

A DC-DC converter plays a major role in many applications such as fuel cell, hybrid electric vehicle, renewable energy system, etc. Among these converters, the bidirectional DC-DC fly-back converters are more attractive because of their simple structure and easy control. However, the power devices present in this converter are subjected to high-voltage stresses due to the leakage inductor energy of the transformer. In order to recycle the leakage inductor energy and to minimise the voltage stress on the power devices, the purpose of this paper is to focus on the transformer less bidirectional DC-DC converter with high efficiency.

In order to reduce the switching loss, a few passive elements are added. The auxiliary circuit consists of a resonant inductor and resonant capacitors. This auxiliary circuit affords zero voltage switching function and cancels out the ripple component present in the main inductor current irrespective of the power flow direction.

In this work three topologies of bidirectional converters for BLDC motor are investigated and are compared in terms of mechanical power output and THD.

The paper presents enhanced versions of the converters.

This study aims to present a modified interleaved boost converter (MIBC) topology for improving the reliability and efficiency of power electronic systems.

The MIBC topology was implemented with two parallel converters, operated with a −180 degree phase shift. Using this methodology, ripples are reduced. The state-space model was analysed with a two-switch MIBC for different modes of operation. The simulation was carried out and validated using a hardware prototype.

The performance of the proposed MIBC shows better output voltage, current and power than the interleaved boost converter (IBC) for the solar PV array. The output power of the proposed converter is 1.353 times higher than that of existing converters, such as boost converter (BC) and IBC. The output power of the four-phase IBC is 30 kW, whereas that of the proposed two-phase MIBC is 40.59 kW. The efficiency of MIBC was better than that of IBC (87.01%). By incorporating interleaved techniques, the total inductor current is reduced by 29.60% compared with the existing converter.

The proposed MIBC can be used in a grid-connected system with an inverter circuit for DC-to-AC conversion, electric vehicle speed control, power factor correction circuit, high-efficiency converters and battery chargers.

The work presented in this paper is a modified version of IBC. This modified MIBC was modelled using the state-space approach. Furthermore, the state-space model of a two-phase MIBC was implemented using a Simulink model, and the same was validated using a hardware setup.

This paper aims to present an analysis of a hybrid high‐voltage switch based on the parallel connection of IGBT and IGCT. The proposed configuration combines the advantages of both semiconductors, resulting in substantially reduced power losses. Such energy efficient switches could be used in high‐power systems where the requirements of high switching frequency or decreased cooling systems are a major concern.

The operation principle of the switch is described and simulated. The power dissipation is estimated at different operation conditions. Further, the implementation possibilities of the proposed switch configuration in a three‐level NPC inverter are analysed. The operation with the proposed PWM control algorithm is simulated and inverter power loss distribution is estimated.

According to estimations, the proposed hybrid switch configuration allows the reduction of total losses in semiconductors by at least 50 percent. If two of these switches are used in a three‐level NPC inverter as outer switches, the total losses of the inverter are reduced by 27 percent, at the same time the losses in the most stressed semiconductor device are reduced by a factor of 2.25. Therefore, achieving higher power density is possible.

The proposed switch configuration is intended for high‐power (>500 KVA) industrial, marine and railway traction systems, such as FACTS and high power variable frequency AC drives.

The paper presents the novel energy‐efficient high‐voltage switch based on the parallel connection of commercially available IGBTs and IGCTs.

The DC‐DC converters which convert one level of electrical voltage to the desired level are widely used in many electrical peripherals. During the past two decade, many different control laws have been developed. The proportional‐integral (PI) control and sliding‐mode control have been carried out for the DC‐DC converters since they are simple to implement and easy to design. However, its performance using PI control and sliding‐mode control is obviously quite limited. The purpose of this paper is to a self‐tuning nonlinear function control (STNFC) propose for the DC‐DC converters. The adaptation laws of the proposed STNFC system are derived in the sense of Lyapunov function, thus not only the controller parameters can be online tuned itself, but also the system's stability can be guaranteed.

In general, the accurate mathematical models of the DC‐DC converters are difficult to derive. This paper proposes a model‐free STNFC design method. Since the proposed STNFC uses a simple fuzzy system with three fuzzy rules base to implement the control law, the computational loading of the fuzzy inference mechanism is slight. So the proposed STNFC system is suitable for the real‐time practical applications. The controller parameters of the proposed STNFC system can online tune in the Lyapunov sense, thus the stability of closed‐loop system can be guaranteed.

The proposed STNFC system is applied to a DC‐DC converter based on a field‐programmable gate array chip. The experimental results are provided to demonstrate the proposed STNFC system can cope with the input voltage and load resistance variations to ensure the stability while providing fast transient response.

The proposed STNFC approach is interesting for the design of an intelligent control scheme. The main contributions of this paper are: the successful development of STNFC system without heavy computational loading. The parameter‐learning algorithm is design based on the Lyapunov stability theorem to guarantee the system stability; the successful applications of the STNFC system to control the forward DC‐DC converter. And, the proposed STNFC methodology can be easily extended to other DC‐DC converters.

The purpose of this study is to help the researchers, public, industries and government to realize the tremendous trends to improve the power quality of both sources and load side.

The work carried out in the Facts device and power quality issues.

Maintaining the quality of electric power is always a challenging task. The effect of power electronics devices leads to improper power quality. The use of FACTS devices is preferably the best approach to treat power-quality-related problems. Usually, all FACTS devices are constructed to operate on the side of either the source side or the load.

This paper explores a broad comprehensive study of various types of power quality problems and classification of FACTS devices with its recent developments. Furthermore unified power quality conditioner (UPQC) is particularly reviewed to highlight the advantages over other compensating devices. An exhaustive study of literature has been carried out and most significant concepts are presented