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The linear model of the three-phase voltage source rectifier (VSR) proposed before could not provide an accurate description for the stability and dynamics performance when the output power is high, the inductances are large or the boost ratio is high. Hence, an item of Right-Half Plane Zero (RHPZ), which contains the output power, the inductances and the boost ratio, is introduced into the linear model in this paper, where its derivation and physical interpretation are also provided. After the introduction, the quantitative analysis for the RHPZ effects, including the decrease of the stability, the deterioration of the dynamic performance and the overshoot of the DC-link voltage, are provided in this paper. According to the analysis, a novel control strategy is proposed to enhance the stability to improve the dynamic performance and to restrain the voltage overshoot. Finally, simulation and experimental results verify that this control strategy has a great validity to reduce the RHPZ effects.

The series-series compensation topology is widely adopted in many wireless power transfer applications. For such systems, their wireless power receiver part typically involves a DC-DC converter with front-stage full-bridge diode rectifier, to process the high-frequency transmitted AC power into a DC output voltage for the load. It is recently reported that the current source nature of the series-series compensation will introduce right-half-plane (RHP) zeros into the small-signal transfer functions of the DC-DC converter of the wireless power receiver, which will severely affect the stability and dynamic response of the system. To resolve this issue, in this paper, it is proposed to adopt a different rectifier configuration for the system such that the input current to the DC-DC converter becomes controllable to eliminate the presence of RHP zeros of the small-signal transfer functions of the system. This rectifier can be applied to different wireless power receivers using the buck, buck-boost, or boost converters. As compared with the original wireless power receivers, the modified ones feature minimum-phase characteristics and hence ease the design of compensator. Theoretical and experimental results are provided. The comparative experimental results verify the elimination of the RHP zero, improved dynamic responses of reference tracking and against load disturbances, and a larger stability margin., Comment: IEEE Transactions on Power Electronics, 2021

In wireless power receiver systems, the buck converter is widely used to step down the higher rectified voltage derived from the wireless receiver coil, to a lower output voltage for the immediate battery charging process. In this work, the presence and effect of the right-half-plane (RHP) zeros found in the small-signal inductor-current-to-duty-ratio and output-voltage-to-duty ratio transfer functions of the buck converter in the wireless power receiver system on the control performance, are investigated. It is found and mathematically proved that the RHP zeros are introduced by the current source nature of the system attributed to the series-series compensation and finite DC-link capacitance. The RHP zero not only results in non-monotonic open-loop dynamic response but also complicates the design of feedback control and causes potential closed-loop instability. Theoretical and experimental results are provided to validate the presence of the RHP zeros and their effect on open-loop and closed-loop dynamic responses., 11 pages. IEEE Transactions on Power Electronics 2020 (Early access)

This brief mainly focuses on discussing computational method of determining whether step responses are nondecreasing for linear time invariant (LTI) systems, including negative real pole systems and complex pole systems. A modified theorem of Jayasuriya and Dharne and a useful fact are offered to deal with negative real pole systems which may have right half plane (RHP) zeros. A necessary condition is presented for complex pole systems to have non-decreasing step responses. Besides, an approximated method is further given as an improvement for determining step responses of complex pole systems.

In order to minimize the common mode leakage current and capability to supply both dc and ac outputs simultaneously, a transformerless wide operating range minimum phase interleaved hybrid converter for photovoltaic applications is presented in this article. The proposed hybrid converter has wide operating ranges of duty ratio ( $D$ ) and modulation index ( ${M_i}$ ), and can be operated at both the conditions, $D + {M_i} \geq 1$ and $D + {M_i} \leq 1$ , which increases the dc gain and improves the ac output quality. Moreover, the proposed hybrid converter exhibits minimum phase behavior as the right half plane zero is eliminated, which enables simpler controller design and facilitates improved bandwidth with higher load current. A hybrid pulsewidth modulation technique is developed for the proposed hybrid converter to minimize the high-frequency common mode voltage terms of the parasitic capacitor and to regulate both the dc and ac outputs simultaneously. The performance of the proposed hybrid converter is compared with other similar topologies to bring out its advantages. Detailed mathematical modeling of the proposed hybrid converter is carried out and a 930-W laboratory prototype is developed to verify its performance.

The dynamic operation of the conventional boost converters is limited in the continuous conduction mode, due to the presence of at least one right‐half plane (RHP) zero in their control transfer function which can limit the open‐loop bandwidth of the converter. This problem complicates the control design for the output voltage regulation and conversely influences the closed‐loop system stability. To cancel this problem, a new step‐up boost converter using the magnetic coupling and the switched capacitor (SC) is presented. In the proposed converter the effect of the RHP zero can be successfully eliminated, the voltage transfer ratio can be enhanced and the circumstances are provided to reach a small operating duty cycle as well as stress reduction of the diodes and power switch. Using the averaging technique, the state‐space model of the converter is analytically studied and the essential conditions are given for achieving a minimum‐phase structure. Based on the mentioned advantage, a simple classical PI controller for the output voltage regulation is designed. To confirm the theoretical analysis of the proposed converter, simulations and practical results are presented. Also, the performance of the proposed converter is compared with the other boost converters without RHP zero.

The observed dynamical property illustrates that state feedback control may stabilize invariant attractor to stable state in a simple version of hematopoietic stem cell model. The stability character of the positive steady state is analyzed by the computation of the rightmost characteristic roots in complex plane. Hopf bifurcation points are tracked as the roots curve crossing imaginary axis from the left half plane to the right half plane continuously. The bifurcation direction and stability of the bifurcating periodical solution are discussed by norm form computation combined with the center manifold theory. Furthermore, the numerical simulation verifies that instead of chaos, system is stabilized to period-1, 2, 3, 4 and period-7 periodical solutions in some delay windows, and the continuous of periodical solutions is also numerical simulated with varying free parameters continuously.

This study presents the cascaded variable structure control approach with respect to the non-minimum phase nature of the DC–DC Z-source converter (ZSC). The method is based on the sliding mode control technique for output voltage regulation. The control-to-output transfer function of the ZSC contains a right-half-plane (RHP) zero in continuous conduction mode. The RHP zero, obtained by a linearised small-signal model, results in frequency response limitation. In this case, the converter output voltage control should be studied regarding to the RHP zero effect. To alleviate this effect and enhance the dynamic performance, the cascaded sliding mode control method is proposed. The cascaded sliding mode controller guarantees asymptotically minimum phase stability as well as robustness against input voltage variation and load resistance uncertainty. The capability and effectiveness of the proposed control method are supported by experimental results.

The classical boost converter for dc/dc voltage conversion in photovoltaic or fuel cell sources inherits the disadvantage of having a slow dynamical behavior, because of the existence of the right-half plan zero (RHPZ) in its input-to-output transfer function. It is the major challengeable concern in the design of the boost converters needing to work in a continuous-conduction mode. To cancel the right-half plan zero from the transfer function of the classical converters, this paper proposes and analyses a new boost converter with a high voltage gain and minimum phase structure. This converter has a fast dynamic response compared with the conventional boost converter and therefore, it is more suitable for applications with fast dynamic response action to connect an input voltage source to an output load. In order to derive the state-space model of the suggested converter, its steady state performance is studied in details and the essential equations are obtained. The formula of the transfer function is deduced by using the averaging technique and then, the theoretical explanations and assessments are presented to show the main characteristics and superiority of the proposed converter. In addition, a practical hardware system of the designed converter has been built and tested.

We consider the convolution of right half-plane harmonic mappings in the unit disk $$\mathbb {D}:=\{z\in \mathbb {C}:\, |z

Let T and $$\tilde{T}$$ be closed linear operators in a Hilbert space. Let the spectrum of T is in the right half-plane. We suggest the conditions, under which the spectrum of $$\tilde{T}$$ also lies in the right half-plane.

For fuel cell applications, a module-integrated dc/dc converter with the isolation capability is an important part of a power distribution system. It increases the low input voltage of a fuel cell to a desire high voltage and behaves as an interface connection circuit. There are several isolated dc/dc converters for connecting a fuel cell module to a power load. Among them, Flyback converter is a good candidate and widely used for fuel cell applications, due to its simple structure; however, the internal dynamics of a Flyback converter involves a right-half-plane zero (RHPZ), resulting in its performance degradation. Hence, the open-loop gain margin of a Flyback converter is small and its open-loop phase margin is negative, leading to difficulties for development of a voltage-mode controller. The major objective of the article is to address the aforementioned problems and present a new approach for eliminating them. To this end, a modified Flyback topology with ability of the RHPZ elimination is suggested and analyzed in this study and also, the superior performance of the modified converter is demonstrated in comparison with a classical Flyback converter. Then, the dynamical model of the designed circuit is derived using the averaging method and the design rules are determined. In addition, the theoretical model of the developed converter is validated via simulations and experiments. To keep the load voltage of this topology at a fixed value and, show its good performance for industrial applications, the type-II/III controllers are designed and the obtained simulated and practical results are introduced.

Purpose Control-signal-to-output-voltage transfer function of the conventional boost converter has at least one right-half plane zero (RHPZ) in the continuous conduction mode which can restrict the open-loop bandwidth of the converter. This problem can complicate the control design for the load voltage regulation and conversely, impact on the stability of the closed-loop system. To remove this positive zero and improve the dynamic performance, this paper aims to suggest a novel boost topology with a step-up voltage gain by developing the circuit diagram of a conventional boost converter. Design/methodology/approach Using a transformer, two different pathways are provided for a classical boost circuit. Hence, the effect of the RHPZ can be easily canceled and the voltage gain can be enhanced which provides conditions for achieving a smaller working duty cycle and reducing the voltage stress of the power switch. Using this technique makes it possible to achieve a good dynamic response compared to the classical boost converter. Findings The observations show that the phase margin of the proposed boost converter can be adequately improved, its bandwidth is largely increased, due to its minimum-phase structure through RHPZ cancellation. It is suitable for fast dynamic response applications such as micro-inverters and fuel cells. Originality/value The introduced method is analytically studied via determining the state-space model and necessary criteria are obtained to achieve a minimum-phase structure. Practical observations of a constructed prototype for the voltage conversion from 24 V to 100 V and various load conditions are shown.

We consider two-dimensional continued fractions whose elements belong to an angular domain of the right half plane and establish sufficient conditions of their figured relative stability under perturbations. We also obtain an estimate for the relative error of figured approximants of the investigated two-dimensional continued fractions.

This study proposes a minimum phase bipolar converter for dc microgrid applications, which is derived from the combination of C'uk and Sepic converters with some modifications in both of them in order to get a minimum phase system. In the proposed bipolar converter (PBC), the equivalent series resistance of transfer capacitors of both C'uk and Sepic converters is increased by adding resistances and introducing magnetic coupling between the filter inductors of the Sepic converter with a series RC network. These circuit modifications eliminate right half plane zero from the PBC and thereby make it a minimum phase, unlike the conventional C'uk-Sepic bipolar converter. Due to the minimum phase behaviour, the proposed converter can deliver high load current, achieves high bandwidth and facilitates simpler controller design in contrast to the conventional C'uk-Sepic bipolar converter. Detailed steady state and dynamic modelling of the PBC has been carried out in order to show its advantages. A 500 W laboratory prototype has been developed and implemented using field programmable gate array-based system to verify the operation of the proposed converter.

This paper is to give a univalent criterion and a geometric property of the convolution of two right half-plane harmonic mappings f0(z) and f (z), where f0(z) is canonical and the second complex dilatation w(z) of f (z) is of the form w(z) = - z-a/1-az z-b/1-bz.

DC-DC converters, classified as nonlinear systems are needed to be averaged and linearized to obtain a linear time-invariant model and the design of high-performance control for them is a challenging issue. In general, a good control for dc-dc converters should ensure stability at all operating conditions. Moreover, a good response in terms of rejection of load variations, input voltage changes and parameter uncertainties are also required for a typical control scheme. A major problem arises in the controller design when the transfer function of control-to-output voltage has right-half plane (RHP) zero. The effect of RHP zero predominates in the transfer functions of boost and buck-boost converters leading to a tedious controller design. Hence in this work, the design of linear and nonlinear controllers for a dc-dc boost converter is discussed. To achieve large signal stability, robustness, good dynamic response and simple implementation, an additional inner loop employing sliding mode control (SMC) with boundary layer is proposed in the current mode control (CMC) scheme is employed in this work. The conventional PI controller is then designed for the outer loop. To reduce chattering and to improve transient response, a fuzzy sliding mode control (FSMC) is proposed in the inner loop of CMC. Extensive simulation studies are carried out for dc-dc boost converter with RHP zero to verify the merits of FSMC over SMC using Matlab/Simulink software.

DC grid interfaces for supercapacitors (SCs) are expected to operate with a wide range of input voltages with fast dynamics. The class-C DC-DC converter is commonly used in this application because of its simplicity. However, it does not work if the output voltage (V2) becomes smaller than the input voltage (V1). The non-isolated bi-directional Buck–Boost DC-DC converter does not have this limitation. Its two half-bridges provide a means for controlling the power flow operating in the conventional dual-state mode, as well as multi-state, tri, and quad modes. These can be used for mitigating issues such as the Right Half Plane (RHP) zero that has a negative impact on the dynamic response of the system. Multi-state operation typically requires multi-variable control, which is not easy to realize with conventional PI-type controllers. This paper proposes a unified controller for multi-state operation. It employs a carrier-based modulation scheme with three modulation signals that allows the converter to operate in all four possible states and eight different modes of operation. A mathematical model is developed for devising a multi-variable control scheme using feedback linearization. This allows the design of control loops with simple PI controllers that can be used for all multi-state modes under a wide range of operating conditions with the same performance. The proposed scheme is verified by means of simulations.

This work presents a novel boost converter with time-based control for LED display applications. Using the inductor current, the right-half-plane zero of the CCM control-to-output transfer function is eliminated to improve dynamic performances with no extra off-chip component or power switch. To increase efficiency at light loads, a PFM operating mode with seamless PFM-to-CCM transition is included. The prototype implemented in a 0.18µm BCD process provides a regulated output voltage of 5V with a 2.5-to-4.5V input voltage range. With a 3.5V input, the efficiency reaches a peak of 96%, while it is above 90% down to 10mA loads. The area occupation of the time-based PID controller is about 0.16 square millimeters with a quiescent current of 300µA. The converter bandwidth is increased by a factor of about 5 with respect to a standard compensation scheme.

Designed for the discharge regulator of the power supply controller with 100V bus voltage, using Superboost as the boost topology, introducing a damping network on the traditional Superboost circuit, eliminating the right half plane zero in the transfer function, and improving the stability of the system In order to meet the requirements of wide input range and high dynamic response of the discharge regulation circuit, the voltage and current double closed-loop control loop is designed, and a series of optimized designs are used to improve the efficiency of the converter. The stability of the loop is verified by the Bode plot, and the experimental results of the 500W prototype are finally given, which verifies the correctness of the theoretical analysis.

A transient response enhancement circuit applied in peak-current mode converter is proposed, which can improve the system transient response. Because the bandwidth of the traditional peak-current mode Boost converter is limited by the right half plane zero, the transient response speed is limited during the load step. A circuit is proposed which can adaptively adjust the output voltage of the Boost converter and optimized the system transient response. The proposed circuit is simulated and verified by 0.18um BCD process. The recovery time was reduced from 67$\mu$s to 49$\mu$s while the load current changed from 1A to 200mA. The recovery time was reduced from 47$\mu$s to 35$\mu$s while the load current changed from 200mA to 1A.

Three fourth-order buck-boost converters with improved dynamic response are proposed. The improved dynamic response is achieved starting from the uncoupled inductors topologies and performing reverse coupling. This leads to the shift of the right half plane (RHP) zeros to the left half plane (LHP). The state-space small signal model is developed and the control-to-output transfer functions are derived. A comparison is made to the uncoupled and direct coupled topologies revealing the RHP zeros elimination. The simulations confirm that also with reverse coupling the input and output currents still maintain their smooth nature.

A Single-Inductor Dual-Output (SIDO) Boost converter with 92.44% peak efficiency and fast transient response is presented. Conventional SIDO Boost converter exhibits large output voltage ripples and slow transient response due to the right-half-plane (RHP) zero and larger inductor current. By eliminating inherent RHP zero and decreasing the inductor current, the proposed SIDO Boost converter obtains 92.44% peak efficiency and shortens the load transient response time to 10us when one load current steps up from 50mA to 150mA and another fixed.

References [17, Chapter 6] and [18, Chapter 6] were devoted to the basics of control theory when compared with number theory, especially in the light of the deep theory of zeta-functions including number-theoretic mean averages, whose view is rather unique. Prior to this, there were two trends of applications of mathematics to control theory, i.e. application of functional analysis, cf. e.g. [7,8], and that of algebraic geometry [4,5].

We prove that convolutions of harmonic right half-plane mappings with harmonic vertical strip mappings are univalent and convex in the horizontal direction. The proofs of these results make use the Gauss–Lucas Theorem. Our results show that two recent conjectures, the one by Kumar, Gupta, Singh and Dorff, and the one of Liu, Jiang and Li, are true. Moreover, examples of univalent harmonic mappings related to the above-mentioned results are presented, suggesting that the bounds given by our results may be sharp.

Spatially localized patterns have been observed in numerous physical contexts, and their bifurcation diagrams often exhibit similar snaking behavior: symmetric solution branches, connected by bifurcating asymmetric solution branches, wind back and forth in an appropriate parameter. Previous papers have addressed existence of such solutions; here we address their stability, taking the necessary first step of unifying existence and uniqueness proofs for symmetric and asymmetric solutions. We then show that, under appropriate assumptions, temporal eigenvalues of the front and back underlying a localized solution are added with multiplicity in the right half plane. In a companion paper, we analyze the behavior of eigenvalues at λ = 0 and inside the essential spectrum. Our results show that localized snaking solutions are stable if, and only if, the underlying fronts and backs are stable: unlike localized non-oscillatory solutions, no interaction eigenvalues are present. We use the planar Swift–Hohenberg system to illustrate our results.

Consider a function f analytic in the open unit disk and normalized so that f(0) = f′(0) − 1 = 0. The methods of the theory of first-order differential subordinations are used to obtain sufficient conditions for the function f to have bounded turning, i.e., for the real part of its first derivative to map the unit disk onto the right half plane. In addition, several open problems are posed.

In the conventional power systems, the synchronous generators (SGs) are known to suffer stability issues under weak grid conditions. Recently, similar problems are observed in the inverter interfaced systems, including the full voltage source converter (VSC)-based high-voltage DC, and partial VSC interfaced doubly fed induction generator (DFIG) systems, but the root causes of these instabilities in reality are not completely understood yet. This study aims to provide a possible unified explanation for the origin of these instability issues. With the experiences of SG's instability mechanism, for the VSC and DFIG systems, the dynamics of outer power flow controls are mainly focused, and the reduced-order models are parallelly presented first. Then, centralised around the active power control loops of these systems for analysis, it is found that an open-loop zero will move to the right half plane with grid strength decrease. The borders for the occurrence of right-half-plane zeros (RHPZs) are analytically derived. Further, a general interpretation regarding these identified RHPZs' limitations, including the adverse phase lag effect on stability and the attraction effect on the stability boundary, is illustrated. In addition, a uniform explanation for the origin of the RHPZs in these systems is also provided. Time-domain simulations are conducted to validate the analysis.

In this paper, an inequality for a transfer function is obtained assuming that its residues at the poles located on the imaginary axis in the right half plane. In addition, the extremal function of the proposed inequality is obtained by performing sharpness analysis. To interpret the results of analyses in terms of control theory, root-locus curves are plotted. According to the results, marginally and asymptotically stable transfer functions can be determined using the obtained extremal function in the proposed theorem.

This paper studies the asymptotic behaviour of the powers $$C_\varphi ^n$$ of a composition operator $$C_\varphi $$ on certain spaces of holomorphic functions defined on the right half plane $$\mathbb {C}_+$$ . It is shown that for composition operators on the Hardy spaces and the standard weighted Bergman spaces, if the inducing map $$\varphi $$ is not of parabolic type, then either the powers $$C_\varphi ^n$$ converge uniformly only to 0 or they do not converge even strongly.

For a certain class of sequences with multiple terms $$\{\underbrace{\lambda _1,\lambda _1,\ldots ,\lambda _1}_{\mu _1 - times}, \underbrace{\lambda _2,\lambda _2,\ldots ,\lambda _2}_{\mu _2 - times},\ldots \}$$ in the right half-plane $$\mathbb {C}_+$$ , and a doubly-indexed sequence $$\{d_{n,k}{:}\, n\in \mathbb {N},\, k=0,1,\ldots ,\mu _n-1\}$$ of complex numbers satisfying certain growth conditions, we consider an interpolation problem $$\begin{aligned} f^{(k)}(\lambda _n)=d_{n,k}\qquad n\in \mathbb {N},\quad k=0,1,\ldots ,\mu _n-1, \end{aligned}$$ where f is a bounded analytic function in $$\mathbb {C}_+$$ , belonging to the Hardy spaces $$H^1 (\mathbb {C}_+)$$ and $$H^2 (\mathbb {C}_+)$$ .

This paper presents a procedure to parametrize input shapers with piecewise equally distributed time delays. The procedure seeks to minimize residual vibrations around an undesirable frequency but at the same time avoids introducing zeros in the right half plane. This ensures that the introduction of the inverse of the input shaper in a closed feedback loop does not introduce unstable poles in the system. The requirement of stable spectra for the input shaper appears as an additional constraint in a constrained optimization problem that includes minimizing the response time and residual vibrations while preserving required properties of the shaper. The novel introduction of a spectral constraint makes the optimization problem nonsmooth and nonconvex, necessitating special optimization algorithms for its reliable solution. The framework is outlined in detail and the results of the optimization are presented indicating the success of the procedure.

Internal model control (IMC) with optimal H2 minimization framework is proposed in this paper for design of proportional-integral-derivative (PID) controllers. The controller design is addressed for integrating and double integrating time delay processes with right half plane (RHP) zeros. Blaschke product is used to derive the optimal controller. There is a single adjustable closed loop tuning parameter for controller design. Systematic guidelines are provided for selection of this tuning parameter based on maximum sensitivity. Simulation studies have been carried out on various integrating time delay processes to show the advantages of the proposed method. The proposed controller provides enhanced closed loop performances when compared to recently reported methods in the literature. Quantitative comparative analysis has been carried out using the performance indices, Integral Absolute Error (IAE) and Total Variation (TV).

It is well-known that a Z-source inverter (ZSI) depicts non-minimum phase characteristics due to a right half plane zero (RHPZ) in its shoot through duty ratio to output voltage transfer function. The RHPZ creates problems in design of a PID controller for such type of systems by imposing the bandwidth limitations and control actions. In this article, the Jaya optimization approach is adopted to reduce the order of ZSI and to obtain the optimized tuning parameters of PID controller. The peak value of DC link voltage is indirectly calculated by measurement of the input supply voltage and the capacitor voltage. The transfer function of control to peak DC link voltage of traditional ZSI is used to get the tuning parameters of PID controller. The MATLAB/Simulink simulation platform is utilized to validate the proposed approach.

This paper presents a comparison of two controllers applied to a nonminimum phase Buck and Boost converter. The design of controllers come from reduced order models and combine an Internal Model Structure (IMS) with Sliding Mode Control (SMC). This combination of control schemes solves the nonminimum phase problem in the system. The first controller proposed is based on a First order plus dead time (FOPDT) model of system and the second controller is based on a second order model of system with the right half plane zero (SOPRHZ). The tuning parameters of controllers are obtained using the tuning equations designed for chemicals processes. Additionally, they are obtained with Particle Swarm Optimization (PSO) algorithm to improve the results obtained with tuning equations. The performance of the controllers is analyzed and compared by simulation.

In this paper, we propose a design method of the multiplex-feedback control system having low-sensitivity and robust stability for a single-input/single-output time-delay system with a varying number of poles in the closed right half plane. The low sensitivity control has high-performance of input-output property. However, it is well-known that the low-sensitivity control often cannot maintain the control system robust stability. According to Yamada, there is a low sensitivity control system design method maintaining robust stability for a single-input/single-output minimum-phase system with a varying number of unstable poles. In addition, Yu et al. expand the result of Yamada and propose a design method of the multiplex-feedback control system that has low-sensitivity characteristics less than a conventional two-degree-of-freedom control system. In this paper, we expand the result of Yamada and Yu et al. and propose a design method of the multiplex-feedback control system with robust stability that has low-sensitivity characteristics less than a conventional feedback control system for a single-input/single-output time-delay plant having a varying number of unstable poles.

A minimum phase dual output hybrid converter for DC microgrid applications is proposed in this paper, which is capable of supplying power to AC and DC loads simultaneously. The circuit configuration of the proposed converter eliminates the right half plane zero (RHPZ) from the DC control-to-output transfer function, making the system minimum phase. Due to the minimum phase behavior, the proposed converter is capable of meeting high load current requirement while maintaining closed-loop stability. Further, the minimum phase behavior of the proposed converter also facilitates simpler controller design and faster dynamic response. The proposed converter can be applied to perform dc/ac and dc/dc power conversions for renewable energy sources. A hybrid PWM switching scheme is developed to realize the same. Detailed mathematical modeling is carried out to demonstrate the properties of the proposed converter. A 645 W laboratory prototype is developed to validate the proposed topology experimentally.

Although recent versions of Cadence PSpice contain functions that can derive regulation loop bode plots from a real time switching model, it is still very attractive and necessary for larger system analysis to have an accurate and precise linearized model of DC/DC converter stages, which covers both continuous and discontinuous conduction mode. It is also important that such a model provide the same transfer function as the simulated real time DC/DC converter, including Right Half Plane Zero (RHPZ) effects of boost family converters and load dependent inductance. A novel model, that fulfill these requirements has been developed and is presented in detail in this paper.

In this paper, we consider a robust stability condition of the double feedback control system with low-sensitivity for single-input/single-output time-delay system having an uncertainty in which has a varying number of the closed right half plane. The robust stability problem is to stabilize the control system for the uncertainty. The control system is made robust stability if the complementary sensitivity function of the control system is made small value. On other hands, the control system has the low-sensitivity characteritics such as reducing the influence of uncertaity, the disturbance and etc. if the sensitivity function of the control system is made small value. However, it is difficult that the control system with robust stability has the low-sensitivity characteristics because the sum of the sensitivity function and the complementary sensitivity function is equal to 1. According to Yamada and Yu et al., we can construct the high-performance control system such as having the robust stability and low-sensitivity. The aim of this paper is to expand the result of Yamada and Yu et al. and propose the design method of the control system with robust stablity and low-sensitivity by reducing the influence of uncertainty.

The right-half-plane (RHP) zero can be eliminated in the proposed buck-boost (BB) converter to achieve fast transients for Internet-of-Thing (IoT) applications. The pseudo-boost mode in the BB converter eliminates one power switch in the current path and ensures that the continuous inductor current is half of the conventional design value to achieve 97.46% peak efficiency. Besides, the output voltage ripple is reduced to 7mV. By inserting an additional phase, a smooth transition between the buck and pseudo-boost modes ensures a voltage drop less than 15mV. The slope-based transient enhancement (SBTE) circuit accelerates transient response in 9 $\mu$S with a load variation of 400 mA.

In spacecraft applications, a step-up converter used to the battery discharge regulator (BDR) should provide a sufficient phase margin and wide bandwidth to satisfy highly demanded requirement of the bus voltage regulation. Thus, Weinberg converter, which has no right half plane zero, has been widely used. However, Weinberg converter requires lots of components, so that BDR cannot avoid the power density degradation. In additions, due to the leakage inductances the output current spike increases output voltage ripple largely. In order to overcome the abovementioned problems, a new boost-forward integrated converter is proposed. Comparing with Weinberg converter, the proposed converter has small magnetic size and eliminates one powering diode. At the same time, there is no the output current spike. In additions, it has a high phase margin and bandwidth. Therefore, the proposed converter is adaptable to increase the power density of spacecraft applications especially BDR. The improvement of proposed converter is verified by 500W/50V prototype model.

This paper presents a novel two-phase interleaved inverse-coupled inductor boost (IICIB) without right half-plane (RHP) zeros. The input and output inductors in the IICIB have been all integrated into one magnetic core, and there is a 180° phase shift between the driving signals. Thanks to the coupling relationship between the four inductors in the new proposed converter, a smaller core size and higher power density can be achieved because the core size is normally determined by the energy storage requirement. Meanwhile, with the RHP zeros eliminate, a higher bandwidth with wide range of control over the applied input or output voltage can be achieved. The new converter not only has the aforementioned advantages, but also shows great potential for current ripple reduction as a result of the interleaved structure. Finally, experimental verification is provided to illustrate the effectiveness of the theoretical findings and design approaches.

We investigate the spectral stability of travelling wave solutions in a Keller-Segel model of bacterial chemotaxis with a logarithmic chemosensitivity function and a constant, sublinear, and linear consumption rate. Linearising around the travelling wave solutions, we locate the essential and absolute spectrum of the associated linear operators and find that all travelling wave solutions have parts of the essential spectrum in the right half plane. However, we show that in the case of constant or sublinear consumption there exists a range of parameters such that the absolute spectrum is contained in the open left half plane and the essential spectrum can thus be weighted into the open left half plane. For the constant and sublinear consumption rate models we also determine critical parameter values for which the absolute spectrum crosses into the right half plane, indicating the onset of an absolute instability of the travelling wave solution. We observe that this crossing always occurs off of the real axis.

We consider the convolution of half-plane harmonic mappings with respective dilatations $(z+a)/(1+az)$ and $e^{i\theta}z^{n}$, where $-1, Comment: 11 pages, 8 figures; Will appear in the Journal "Computational Methods and Function Theory"

A magnetically coupled boost (MCB) converter with the enhanced equivalent series resistance (ESR) of the filter capacitor for DC microgrid applications has been presented in this study. The proposed MCB converter with enhanced ESR filter capacitor uses only four state variables and exhibits a fourth-order minimum phase behaviour because of the complete elimination of right half plane zero. The characteristic of displaying fourth-order minimum phase behaviour of the proposed MCB converter with the enhanced ESR filter capacitor makes the design and analysis simple. Closed-loop operation of the proposed MCB converter with the enhanced ESR filter capacitor with photovoltaic input using maximum power point tracking has been carried out to verify its applicability in DC microgrid. Steady state and dynamic modelling of the MCB converter has been carried out to demonstrate its advantages. The proposed algorithm is validated on a 145 W prototype through simulation and experimentation.

Major power grid blackouts in various parts of the world are characterized by voltage collapse. This paper studies the blackout case in the Indian power grid due to voltage collapse in the inter-regional corridor. First, the computer simulation models are tuned to match responses from the phasor measurement units at various locations in the grid. The inter-area mode with the frequency of 0.3 and 0.5 Hz with reduced damping were observed and resulted due to switching actions that occurred during the disturbance. This paper simulates the complex power grid network for various loading conditions of Northern region using power system simulator for engineering. Further, the system variables are analyzed using Prony method to estimate the inter-area mode for different NR loading conditions. The eigen values associated with the 0.3 Hz mode depict the movement from open left half plane into open right half plane with a slight increase in the parameter indicating “hopf bifurcation.” This paper also discusses the maximum loading capacity for the inter-regional lines in-order avoid loss of small signal stability, and highlights the use of real time phasor measurement unit measurements in-order to estimate and track the oscillatory modes.