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Digital Controller for an Electric Wheelchair Based on a Low-Cost Hardware

IEEE LATIN AMERICA TRANSACTIONS 2015年第10期13卷 3221-3227页

作者： Caporal, R. M. Leon, A. V. Flores, R. O. Huerta, E. B. Hernandez, J. C. H. Inst Tecnol Apizaco Tlaxcala Mexico

This paper presents a digital motion controller of an electric wheelchair by using a low-cost real-time microcontroller unit (MCU) and an own developed power electronic drive. The speed control of the wheels is implemented through a digital pulse-width modulation technique which is varying with the reference generated by a low-cost joystick. Voltage regulators and power converters are implemented to supply correct voltage levels to control cards and to the DC motors from batteries. Experimental results which have been obtained by using the MCU, the mechanical structure of a used electric wheelchair and the developed electronic drive demonstrate that the proposed digital controller meets the user requirements in terms of reliability, good driving and fair economic cost.

关键词： DC-DC converter digital control motion control direct current motor pulse-width modulation real-time control

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Constant-current control method of multi-function electromagnetic transmitter

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REVIEW OF SCIENTIFIC INSTRUMENTS 2015年第2期86卷 1-10页

作者： Xue, Kaichang Zhou, Fengdao Wang, Shuang Lin, Jun Jilin Univ Coll Instrumentat & Elect Engn Changchun 130021 Peoples R China Jilin Univ Minist Educ Key Lab Geoexplorat & Instrumentat Changchun 130021 Peoples R China

Based on the requirements of controlled source audio-frequency magnetotelluric, DC resistivity, and induced polarization, a constant-current control method is proposed. Using the required current waveforms in prospecting as a standard, the causes of current waveform distortion and current waveform distortion's effects on prospecting are analyzed. A cascaded topology is adopted to achieve 40 kW constant-current transmitter. The responsive speed and precision are analyzed. According to the power circuit of the transmitting system, the circuit structure of the pulse width modulation (PWM) constant-current controller is designed. After establishing the power circuit model of the transmitting system and the PWM constant-current controller model, analyzing the influence of ripple current, and designing an open-loop transfer function according to the amplitude-frequency characteristic curves, the parameters of the PWM constant-current controller are determined. The open-loop transfer function indicates that the loop gain is no less than 28 dB below 160 Hz, which assures the responsive speed of the transmitting system;the phase margin is 45 degrees, which assures the stabilization of the transmitting system. Experimental results verify that the proposed constant-current control method can keep the control error below 4% and can effectively suppress load change caused by the capacitance of earth load. (C) 2015 AIP Publishing LLC.

关键词： CONSTANT current sources MAGNETOTELLURICS RESEARCH INDUCED polarization pulse-width modulation ELECTRIC circuits

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Performance of common-mode-voltage-cancellation PWM strategies with consideration of commutation residues due to double-switching waveforms

Performance of common-mode-voltage-cancellation PWM strategi...

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IEEE Energy Conversion Congress and Exposition

作者： Mehdi Messaoudi Arnaud Videt Nadir Idir Hocine Boulharts Heu Vang University of Lille L2EP laboratory Cité Scientifique 59655 Villeneuve d'Ascq France Schneider Toshiba Inverter Rue André Blanchet 27120 Pacy-sur-Eure France Toshiba Schneider Inverter 1-19-30 Aoi Higashi-ku Nagoya 461-0004 Japan

ISBN: (纸本)9781509007387

This paper focuses on pulse-width modulation (PWM) strategies that aim at cancelling common-mode (CM) voltage generated by power converters. In the typical use case of frequency converters, such strategies perform simultaneous switching between different inverter legs, so that their effects on CM voltage cancel each other. Doing so, the resulting CM voltage is reduced to mere commutation residues because simultaneous switching voltage waveforms may not be identical nor perfectly synchronous. Based on a PWM strategy that theoretically cancels the CM voltage generated by a variable-speed drive, this paper highlights the influence of desynchronization effects, commutation speeds, and different waveforms due to instantaneous currents, on the resulting CM voltage spectrum. Practical rules are derived in order to optimize the electromagnetic compatibility (EMC) performance of such PWM strategies.

关键词： variable-speed drives Electromagnetic compatibility common-mode voltage pulse-width modulation double switching

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A Single-phase Hybrid Multi-level Inverter

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ELECTRIC POWER COMPONENTS AND SYSTEMS 2015年第3期43卷 252-259页

作者： Odeh, Charles Ikechukwu Univ Nigeria Dept Elect Engn Nsukka 410001 Nigeria

This article presents a single-phase 17-level hybrid multi-level inverter. The cascaded unit is made up of two five-level inverter configurations: a diode-clamped inverter and an inverter constituted of a main inverting H-bridge leg and level-clamping half-bridge circuit. The asymmetrically cascaded inverters have a separate DC input ratio of 1:3 that affects reduction in the power circuit component count in the single-phase multi-level inverter system. The operational principles, modulation schemes, and switching functions have been analyzed in detail. Fast fourier transform analysis of the output voltage waveform was carried out, and a low total harmonic distortion value of 7.61% was obtained. The validity of the proposed hybrid multi-level inverter is verified through simulation and experimental results.

关键词： inverter multi-level pulse-width modulation total harmonic distortion hybrid

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RIPPLE COMPENSATION FOR A CLASS-D AMPLIFIER

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SIAM JOURNAL ON APPLIED MATHEMATICS 2015年第4期75卷 1536-1552页

作者： Cox, Stephen M. Mouton, H. Du Toit Univ Nottingham Sch Math Sci Nottingham NG7 2RD England Univ Stellenbosch Dept Elect & Elect Engn ZA-7602 Matieland South Africa

This paper presents the first detailed mathematical analysis of the ripple compensation technique for reducing audio distortion in a class-D amplifier with negative feedback. The amplifier converts a relatively low-frequency audio signal to a high-frequency train of rectangular pulses whose widths are slowly modulated according to the audio signal (pulse-width modulation, PWM). Distortion manifests itself through unwanted audio-frequency harmonics that arise in the output due to nonlinearities inherent in the design. In this paper, we first develop a small-signal model, which describes the fate of small-amplitude perturbations to a constant input, and demonstrate how this traditional engineering tool may be extended to allow one to infer the most significant contributions to the full output in response to a general audio input. We then compute the audio output of the amplifier through a perturbation expansion based on the ratio between audio and switching frequencies. Our results explicitly demonstrate how the ripple compensation technique significantly linearizes the output, thereby reducing the distortion.

关键词： class-D amplifier mathematical model small-signal model Apostol-Bernoulli functions pulse-width modulation

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A pulse-Mode CMOS Power Amplifier for Multi-Band LTE Femtocell Base Stations

A Pulse-Mode CMOS Power Amplifier for Multi-Band LTE Femtoce...

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IEEE MTT-S International Microwave Symposium

作者： Hao-Shun Yang Yi-Jan Emery Chen Jau-Horng Chen Department of Engineering Science and Ocean Engineering National Taiwan University Graduate Institute of Electronics Engineering National Taiwan University

ISBN: (纸本)9781509006991

This paper presents a wide bandwidth fully integrated CMOS power amplifier (PA) suitable for pulse-mode operation. The CMOS PA was implemented in a 90-nm process with core size of 1 mm~2. A pulse-modulated polar transmitter for LTE femtocell applications was constructed with this switching CMOS PA using the aliasing-free digital pulse-width modulation technique. With conventional memoryless digital predistortion, the polar transmitter achieved 23.5% efficiency and 19.5-dBm output power at 2.4 GHz. Moreover, the proposed transmitter can also pass the -45-dBc ACLR requirement over a wide frequency range from the first channel in downlink band-1 to the last channel in downlink band-7 for LTE home femtocell base stations.

关键词： Femtocell base stations Long term evolution (LTE) Power amplifiers pulse-width modulation Radio transmitters

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A PWM Based Fully Integrated Digital Transmitter/PA for WLAN and LTE Applications

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IEEE JOURNAL OF SOLID-STATE CIRCUITS 2015年第5期50卷 1117-1125页

作者： Hezar, Rahmi Ding, Lei Banerjee, Aritra Hur, Joonhoi Haroun, Baher Texas Instruments Inc Kilby Labs Dallas TX 75243 USA

In this paper, we present a 23 dBm PWM based fully digital transmitter designed in standard 45 nm CMOS process. The digital transmitter utilizes sigma-delta modulation and pulse-width modulation to convert high resolution baseband I and Q signals into 3-level switching signals, thereby allowing efficient Class-D PA stages to be used. In addition, cascaded sigma-delta stages and switched-capacitor combining are incorporated into the architecture to significantly reduce the out-of-band quantization noise while maintaining excellent efficiency. The proposed transmitter is fully digital from baseband to RF and can be used to replace the entire analog/RF signal chain in a traditional transmitter. It achieves peak output power of 23 dBm with 47% power-added efficiency (PAE). For an 20 MHz OFDM signal with 8.2 dB peak-to-average power ratio (PAR), the PAE is 23%. The linearity of the digital transmitter meets WiFi spectral mask without any digital predistortion.

关键词： Class-D CMOS power amplifier digital power amplifier LTE pulse-width modulation RF sigma-delta modulation switched capacitor power amplifier transmitter WLAN

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Limiting factors of the response time of the magnetorheological damper

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INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 2015年第2期47卷 541-550页

作者： Strecker, Z. Roupec, J. Mazurek, I. Klapka, M. Brno Univ Technol FME Inst Machine & Ind Design Brno 61669 Czech Republic

Magnetorheological dampers seem to be suitable for the adaptive car suspension systems. For proper operation of the semi-active algorithms (skyhook, groundhook), the force response of the damper must be fast enough. In this paper, the response time of the Delphi vehicle MR damper is examined and the sources of the overall force time response on the control voltage are discussed. One of the main sources of the response time seems to be electro-magnetic circuit of the MR damper. A principle of an optimal controller for reducing response of the coil's current on the control voltage is designed. However, the measured overall force time response with fast current controller was not reduced as expected. Therefore, a FEM simulation of the magnetic circuit was made. It shows that after an optimization of the current controller, eddy currents in the coil's core cause long time response and therefore they are the limiting factor of the response time of the MR damper. These simulations were verified by the measurements and some recommendations about improving the pistons construction are given at the end.

关键词： Magnetorheological damper MR time response pulse-width modulation eddy current

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Volterra Models for Digital PWM and Their Inverses

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS 2015年第10期62卷 2606-2616页

作者： Chierchie, Fernando Aase, Sven Ole Univ Nacl Sur IIIE Alfredo Desages UNS CONICET Dept Ingn Elect & Comp RA-8000 Bahia Blanca Buenos Aires Argentina Univ Stavanger Dept Elect Engn & Comp Sci N-4036 Stavanger Norway

In an all-digital class-D audio amplifier each signal sample is mapped into a pulse using digital pulse-width-modulation (PWM), and this intrinsically generates nonlinear distortion. This article develops discrete-time Volterra models for digital PWM. The analysis considers two types of demodulation filter, an ideal filter which provides insight into the behavior of the PWM itself, and an analog low-order demodulator filter which models the interaction of the PWM mapping with a real demodulator filter. Symmetric, trailing edge, and leading edge PWM are considered. Using the Volterra models, formulae for the inverse systems are developed. This facilitates digital precompensation of the above mentioned distortion by digitally pre-filtering the modulating signal prior to the PWM mapping. This method is first simulated and compared to pseudo-natural PWM, a well-known method for PWM distortion reduction. Moreover, the method is verified by real measurements from a physical realization of the prefilter setup using real-time digital signal processing.

关键词： Nonlinear distortion power amplifiers pulse-width modulation

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Lag-free terminal voltage sensing in low-pass filtered PWM converters

Lag-free terminal voltage sensing in low-pass filtered PWM c...

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IEEE Energy Conversion Congress and Exposition

作者： Adam Shea T. M. Jahns Wisconsin Electric Machines and Power Electronics Consortium (WEMPEC) Electrical and Computer Engineering University of Wisconsin - Madison Madison WI USA

ISBN: (纸本)9781509007387

Several high-performance control algorithms for ac machine drives and other applications require accurate knowledge of the instantaneous converter output voltages. The use of a simple low-pass filter to remove the PWM switching frequency harmonics from the AC voltage measurements introduces undesirable amplitude and phase lag errors into the voltage measurements. This work presents compensation functions that make it possible to compensate these measured filter output voltages for both amplitude and phase lag errors introduced by zero-order-hold samplers and two different types of PWM algorithms. The impact of the selected filter time constant and the required accuracy of the compensating equations relative to the ADC accuracy are also addressed, leading to identification of the optimal filter break frequency for maximum accuracy.

关键词： finite impulse response filter filter pulse-width modulation compensation voltage sensor quantization analog-to-digital conversion inverters

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