Pulse Width Modulation Feedback Research Articles

A novel and easy‐to‐implement modulation scheme for reducing modulation complexity in modular multilevel converter

AbstractModulation strategy plays a key role in the operation of modular multilevel converters (MMC). Although many studies have been carried out on its optimization in MMC, the limitations of hardware implementation are seldom considered. This paper presents a novel and easy‐to‐implement modulation strategy that simplifies both hardware design and application. From the analysis in this paper, the widely‐used modulation methods have the problems of pulse width modulation (PWM) signal feedback and complex carrier configuration in hardware implementation. By setting up a flexible insertion and removal submodule and proposing a capacitor voltage balance algorithm based on duty ratio allocation, the proposed modulation method can allow for the separate design of the Algorithm Unit and the PWM Unit in the hardware, which solves the problem of PWM feedback and reduces the hardware requirement of the trigger system. Moreover, the proposed method can broaden the selection range of processor chips. Finally, a downscaled MMC prototype is built; the proposed method is verified by both simulation and experiment.

Single-chip DC–DC buck converter design based on PWM with high-efficiency in light load

ABSTRACT This research illustrates a DC–DC buck converter with a pulse width modulation (PWM) feedback control loop and capable of power supply voltage range from VDD to 2.5× VDD, which is equivalent to 5–14 V. It is a single chip with area of 1.379 × 0.813 mm2 using 0.5 µm HV CMOS process, where high voltage (HV) MOSFETs, a Dead-time detector, a PWM feedback loop, a control circuit and HV driving transistors are included. The main feature of our design is its capability of shutting off an optimal number of power MOSFETs during light load operation, resulting in a very high conversion efficiency. Most important of all, the optimal solution is analytically proved. The light load efficiency is raised from 31.71% by traditional methods to 67.94% by the proposed design.

Design, Analysis, and Modeling of an Isolated Constant-Current to Constant-Voltage Converter in Cabled Underwater Information Networks

The underwater electric energy conversion modules are the equipment for distributing electric energy to the electric instruments in the cabled underwater information networks (CUINs), which are also related to the normal and stable operation of the underwater systems, the energy foundation and an important part of the network platform. Based on the classic push-pull high frequency switching circuit of constant voltage conversion, an isolated constant-current to constant-voltage (CC–CV) converter based on pulse width modulation (PWM) feedback was proposed in this paper. Through the theoretical analysis of the working principle of the CC–CV converter and the modeling of the converter circuit based on the state space method, it was verified that the designed converter can achieve the constant current to constant voltage transformation by high-frequency PWM feedback. Based on Saber simulation software, the circuit model of the CC–CV converter was built, and the feasibility of the design was proved by simulation analysis. According to the isolated high-frequency switching CC–CV converter circuit, the physical prototype was made. By adjusting the resistance value of the output load, the constant voltage (CV) characteristic of the output voltage of the converter was analyzed. Furthermore, the results show that the output voltage of the designed CC–CV converter is stable and the ripple of output voltage is less than 5%, when the input current or output load resistance is adjusted under the CC output status, which has the CV output characteristic. The CC–CV converter has good rationality and feasibility, and is suitable for the future development of the constant current remote power supply system of CUINs.

Self-Tuning <italic>LCC</italic> Inverter Using PWM-Controlled Switched Capacitor for Inductive Wireless Power Transfer

Wireless power transfer with a self-tuning <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> inverter using pulsewidth modulation (PWM) controlled switched capacitor is proposed in this paper in order to compensate for the variations of Tx inductance. Usually, receivers contain magnetic and conductive materials for shielding and mechanical support. The inductance of the Tx coil is sensitive to the variation of Tx–Rx alignment because the interaction between the Tx coil and the Rx magnetic–conductive materials is also varied. It is shown that the detuning of the Tx inductance value exacerbates the losses in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> inverter. In the proposed method, the PWM duty ratio of a single capacitor adjusts the effective output impedance of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> inverter. The PWM feedback loop is designed such that the power factor and the real-part impedance of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> inverter are maximized. The PWM switch is turned <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> at zero voltage and turned <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> with low <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dv</i> / <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dt</i> , minimizing switching losses. Such a soft-switching tunable capacitor can handle higher power compared to the traditional hard-switching capacitor, p-n junction capacitor, or an analog IC capacitor. Another advantage of the proposed technique is the continuity in achievable capacitance value using only one capacitor. The feedback can be fully implemented by analog components, obviating the necessity of digital samplings, ADC/DACs, and microcontrollers. The power of 54 W is transferred at 76.6% and 60.7% with and without the proposed method, respectively.

Small-Signal Analysis of Naturally-Sampled Single-Edge PWM Control Loops

This paper presents a simple method to analyze the behavior of feedback loops that contain a naturally-sampled single-edge pulse-width modulator. A small-signal model is derived by means of simple geometric arguments. It is shown how this small-signal model can be used to analyze the stability of the continuous-time pulse-width modulated feedback loop by using standard $z$ -domain techniques. The strategy relies on familiar concepts like transfer functions and small-signal gains and does not require any in-depth knowledge of nonlinear systems. A simple design process, where the continuous-time compensator is designed directly in the $z$ -domain, is developed and detailed design equations are derived for a PI current regulator. It is shown how the proposed strategy can accurately predict instability that cannot be explained by means of the well-known average model of the pulse-width modulator. The theoretical analysis is confirmed by means of detailed time-domain simulations. The mechanisms that lead to instability are discussed and an equation for the critical loop gain is derived.

PFM/PWM 듀얼 모드 피드백 기반 LED BLU 구동용 LLC 공진 변환 제어 IC 설계

본 논문은 Pulse Frequency Modulation(PFM)/Pulse Width Modulation(PWM) 듀얼 모드 피드백 기반 LED 백라이트 유닛 구동용 LLC 공진 변환 제어 IC 설계에 대한 내용을 제시한다. 공진형 변환기에서 하나의 변압기를 사용하면서, 두 가지 출력 전압을 생성할 수 있는 구조를 제안하였으며, Master 출력은 PFM 방식으로 Slave 출력은 PWM 방식으로 제어하도록 설계 하였다. 2차 측 Master 출력을 제어하기 위해서 파워 스위치 제어 신호의 주파수를 조절하는 PFM 피드백과 2차 측 Slave 출력을 제어하기 위해서 파워 스위치 제어 신호의 펄스 폭을 조절하는 PWM 피드백 회로를 설계하였다. 설계된 IC는 <TEX>$0.35{\mu}m$</TEX> 2 Poly 3 Metal BCD(Bipolar-CMOS-DMOS) 공정을 이용하여 레이아웃 되었으며, 면적은 <TEX>$2.3mm{\times}2.2mm$</TEX> 이다. 또한, 설계한 칩은 5 V 공급 전압으로부터 26 mA의 전류를 소모하였다. This paper presents a design of LLC resonant converter IC for LED backlight unit based on PFM/PWM dual-mode feedback. Dual output LLC resonant architecture with a single inductor is proposed, where the master output is controlled by the PFM and slave output is controlled by the PWM. To regulate the master output PFM is used as feedback to control the frequency of the power switch. On the other hand, PWM feedback is used to control the pulse width of the power switch and to regulate the slave output. This chip is fabricated in 0.35um 2P3M BC(Bipolar-CMOS-DMOS) Process and the die area is <TEX>$2.3mm{\times}2.2mm$</TEX>. Current consumptions is 26mA from 5V supply.

Class-D Amplifier Power Stage With PWM Feedback Loop

This paper presents a second-order pulsewidth modulation (PWM) feedback loop to improve power supply rejection (PSR) of any open-loop PWM class-D amplifiers (CDAs). PSR of the audio amplifier has always been a key parameter in mobile phone applications. In contrast to class-AB amplifiers, the poor PSR performance has always been the major drawback for CDAs with a half-bridge connected power stage. The proposed PWM feedback loop is fabricated using GLOBALFOUNDRIES' 0.18-μm CMOS process technology. The measured PSR is more than 80 dB and the measured total harmonic distortion is less than 0.04% with a 1-kHz input sinusoidal test tone.

Pth Moment Exponential Stability of Stochastic PWM Feedback Systems with Time‐Varying Delays

This paper further studies the pth moment exponential stability of stochastic pulse‐width‐modulated (PWM) feedback systems with distributed time‐varying delays. We establish several globally exponential stability criteria for such PWM feedback systems by using Lyapunov‐Krasovskii functional and then present an upper bound of the parameter of PWM when the system is stable and such system has stronger anti‐interference performance than the system without time‐varying delays. Furthermore, we present two examples to show the effectiveness and conservativeness of the theoretical results.

Moment Stability of the Critical Case of PWM Feedback Systems with Stochastic Perturbations

This paper further studies the moment stability of pulse‐width‐modulated (PWM) feedback system which is subjected to multiplicative and additive random disturbance modeled by the derivative of Wiener process. Different from the existing investigation, we focus on its critical case. The linear plant considered herein is assumed to be critically stable; that is, the plant has one and only one pole at the origin, and the rest of the poles are left half of complex plane. We establish several globally asymptotically stability criteria for such PWM feedback systems and then propose an algorithm to calculate the stability bound effectively. Furthermore, we present two numerical examples to show the effectiveness of the theoretical results.

A 25 MHz Bandwidth 5th-Order Continuous-Time Low-Pass Sigma-Delta Modulator With 67.7 dB SNDR Using Time-Domain Quantization and Feedback

This paper introduces a continuous-time low-pass sigma-delta modulator operating with a seven-phase 400 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\,$</tex> </formula> MHz clocking scheme to control time-based processing in the 3-bit two-step quantizer and main digital-to-analog converter (DAC). An on-chip voltage-controlled oscillator and a complementary injection-locked frequency divider are utilized for low-jitter clock signal generation with multiple phases, allowing 3-bit pulse-width modulated feedback with a single-element DAC to avoid performance degradation from unit element mismatch problems associated with conventional multi-bit DACs.

Dynamic Analysis Method of Linear Resonant Actuator With Multimovers Employing 3-D Finite Element Method

This paper proposes the dynamic analysis method of a linear resonance actuator with multimovers under PWM (Pulse Width Modulation) feedback control employing the 3-D finite element method (FEM). The effectiveness of this method is shown by the comparison with the experimental results. Furthermore, the effect of a link-spring on each mover motion is clarified.

Design of Optimal PID Controllers for PWM Feedback Systems With Bilinear Plants

This paper considers the optimal proportional-integral-derivative (PID) controller design for a class of pulsewidth-modulation (PWM) feedback systems with bilinear plants by using the orthogonal-functions approach (OFA). Based on the OFA, an algorithm only involving algebraic computation is derived in this paper for analyzing the PWM feedback systems with bilinear plants, and thus, the optimal PID controller design problem for a class of PWM feedback systems with bilinear plants is transformed into a static-parameters optimization problem represented by algebraic equations; this greatly simplifies the optimal PID control design problem. Then, for the static optimization problem, the hybrid Taguchi-genetic algorithm (HTGA) is employed to find both the optimal parameters of the PID controllers and the optimal PWM patterns for the PWM feedback systems with bilinear plants under the criterion of minimizing an integral quadratic performance index. The proposed new method, which integrates the OFA and the HTGA, is nondifferential, nonintegral, straightforward, and well-adapted to computer implementation. The computational complexity can, therefore, be reduced remarkably. An illustrative example for the electrohydraulic servo PWM feedback systems is given to show that the proposed method is an effective approach.

Pulse-width-modulated feedback control of nonlinear systems: optimal linearization-based digital redesign approach

This paper presents an efficient design methodology for pulse-width-modulated (PWM) feedback control of a nonlinear system. To avoid the non-causality between the PWM controller and the widely used modulation law – the principle of equivalent area, the analogue controller to be modulated is first digitally redesigned based on the optimal linear model of the nonlinear system, and is then PWM redesigned, which is an extension of our previous result. It is shown that the proposed technique achieves a uniformly semi-globally practically asymptotic stability of the actual nonlinear PWM feedback control system. An example is provided to illustrate the effectiveness of the proposed methodology.

Analysis and optimal control of pulse width modulation feedback systems

This paper considers the analysis and optimization problems of a class of pulse width modulation (PWM) feedback systems by using continuous orthogonal functions. Two algorithms only involving algebraic computation are derived to analyse PWM feedback systems and to design both the optimal control gains and the optimal PWM patterns of PWM feedback systems under the criterion of minimizing a quadratic performance index. The illustrated examples show that the proposed algorithms based on continuous orthogonal functions can obtain satisfactory results.

Analysis and optimal control of pulse width modulation feedback systems

This paper considers the analysis and optimization problems of a class of pulse width modulation (PWM) feedback systems by using continuous orthogonal functions. Two algorithms only involving algebraic computation are derived to analyse PWM feedback systems and to design both the optimal control gains and the optimal PWM patterns of PWM feedback systems under the criterion of minimizing a quadratic performance index. The illustrated examples show that the proposed algorithms based on continuous orthogonal functions can obtain satisfactory results.

A novel pulse-density-modulated high-frequency inverter for silent-discharge-type ozonizer

This paper presents a novel prototype of a voltage-source load resonant inverter using insulated gate bipolar transistors for driving a silent-discharge-type ozone-generation tube. Ozone-generation technology has a history of more than 100 years and ozonization has been recognized as one of the best methods for water treatment, desinfection, industrial wastes utilization, and so on. However, some technological difficulties related to efficient ozone production and high cost of the ozone-generating equipment have been significant problems restricting ozone usage in the industrial plants. Introduced in this paper is a pulse-density-modulated high-frequency inverter for a silent-discharge-type ozonizer, which is developed with the aim to improve power conversion and control characteristics of the ozone generation by using advances in power electronic technology. The developed system implements the feedforward control-based pulse-density-modulation control scheme with pulsewidth-modulation feedback control strategy to compensate temperature and other environmental influences on ozone gas output.

Stability analysis of pulse-width-modulated feedback systems

In this paper, we present new Lyapunov and Lagrange stability results for pulse-width-modulated (PWM) feedback systems with linear and nonlinear plants. For systems with linear plants, we consider the noncritical case, where the poles of the transfer function of the plant are all in the left-half of the complex plane and the critical case, where one pole is at the origin while the remaining poles are all in the left-half of the complex plane. For these systems we apply the Direct Method of Lyapunov to establish new and improved results for both Lyapunov and Lagrange stability. As in most existing results for PWM feedback systems obtained by the Lyapunov method, we employ quadratic Lyapunov functions in our analysis. However, in the proofs we make use of different majorizations, requiring hypotheses that differ significantly from those used in the existing results. Additionally, and perhaps more importantly, we incorporate into our results optimization procedures that improve our results significantly. We demonstrate the applicability and quality of our results by means of five specific examples that are identical to examples presented in the literature. For PWM feedback systems with nonlinear plants we show that under reasonable conditions, the stability properties of the trivial solution of such systems can be deduced from the stability properties of the trivial solution of PWM feedback systems with corresponding linearized plant, for both noncritical and critical cases.

Pulse width modulated control of the full bridge buck converter

Two approaches are examined for the design a pulse width modulated (PWM) feedback control scheme regulating a full bridge buck converter in both stabilization and AC signal tracking tasks. The first approach is based on a direct strategy for the specification of a static PWM feedback control which accomplishes asymptotic stabilization to a preselected constant operating point for the output capacitor voltage. The same approach is also examined for the asymptotic output tracking of AC reference signals. The second approach, or indirect approach, proposes a dynamical feedback regulation scheme based on input inductor current stabilization or tracking using reference signals obtained via partial inversion of the system dynamics. The indirect approach emphasizes the use of Fliess' generalized observability canonical form of the average converter model.

Filter design method for a PWM feedback inverter system

A novel approach to filter design for a closed-loop, pulse-width-modulated (PWM) DC-AC inverter system driving an RL load is investigated. The system has a rectangular hysteresis in the forward path and it is closed by current feedback. When it is excited by a sinusoidal input reference, it provides square pulses that produce a nearly sinusoidal current in the load. Using a describing function technique, design equations for the filter are derived. The data needed for the filter evaluation are the amplitude of current ripple and the frequency of square pulses delivered by the power bridge. System simulation and experimental results show that the design of the filter can be based on the method proposed and that the filter can provide a significant reduction of current ripple, or otherwise a significant reduction of switching frequency.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Adaptive feedback stabilization in PWM-controlled DC-to-DC power supplies

In this article, adaptive discontinuous feedback regulators are proposed for the stabilization of switch mode controlled DC-to-DC power supplies of the buck, boost and buck-boost types. Adaptation is performed under the assumption of an unknown LC ‘input’ circuit natural oscillating frequency, unknown RC ‘output’ circuit time constant and unknown input source voltage. An average pulse-width-modulation (PWM) input-current regulation scheme, in continuous conduction mode, which accomplishes indirect stabilization of the average output load voltage, is used as the basis for the adaptive controller design. Adaptation is thus confined to the self-tuning of a (static) duty ratio synthesizer. The actual, discontinuous, adaptive PWM feedback strategy state responses exhibit remarkably good asymptotic convergence properties toward the adaptively controlled average designed responses, thus effectively compensating for the modelling error inherent in the average based feedback controller design. It is shown that onl...