... Tóm tắt luận văn Luận văn thực nhiệm vụ nghiên cứu kỹ thuật điều chế độ rộng xung - PWM (Pulse Width Modulation) cho nghịch lưu đa bậc ghép tầng (Cascade inverter) Thông qua mô Psim đánh giá ... based PWM) Các nghịch lưu áp thường điều khiển dựa theo kỹ thuật điều chế độ rộng xung – PWM (Pulse Width Modulation) qui tắc kích đóng đối nghịch Qui tắc kích đóng đối nghịch đảm bảo dạng áp tải ... Luận Văn Tốt Nghiệp • GVHD: Ts Nguyễn Văn Nhờ Phương pháp điều chế vector không gian (Space vector modulation, Space vector PWM) • Phương pháp Discontinuous PWM Các dạng cấu trúc nghịch lưu áp đa...
... of Abbreviations DSP Digital Signal Processor PWM PulseWidthModulation SPWM Sin Triangle PulseWidthModulation SVPWM Space Vector PulseWidthModulation CMV Common Mode Voltage NPC Neutral Point ... for Operation in Overmodulation Range 73 3.1 Introduction 74 3.2 Modulation Index and Modes of Modulation 75 3.3 Operation in Overmodulation Mode ... point fluctuation problem At low modulation index, the fluctuations can be compensated using redundant switching states But at higher modulation index and in overmodulation region, the neutral point...
... lowvoltage large-current power conversion VI C This paper has dealt with two types of pulse- widthmodulated modular multilevel converters (PWM-MMCs), proposing their control method and verifying ... disabled v∗ B1 Experimental waveforms when only the balancing control was operated under the same modulation index As a result, vC1 was equal to vC2 in Fig because the chopper-cells and utilize ... waveforms when the coupled inductor was utilized In Fig 13, each chopper-cell was operated at a modulation index of 0.83, while the balancing control using the load current was utilized (see the...
... signal-to-noise measurements of the PCM system To investigate synchronous and asynchronous PCM techniques To investigate properties of the TDM-PCM communication system EQUIPMENT LIST PC With ... block paramters of the quantizer encode and the decode blocks The triger signal is provided using a pulse generator figure 8A (f) Block Parameters Enabled quantizer encode Similarly the block parameters...
... only one chip where a pulse occurs and on average 4.5 empty chips, so the probability that a false pulse will be detected is higher than the probability that a correct pulse will not be detected ... increase in information capacity over isochronous modulationtechniques Simpler receiver complexity and very high achievable bit-rates make PIM modulation very attractive for IR-UWB short-range ... Networking, vol 2008, 2008 [9] C J Mitchell, G T F de Abreu, and R Kohno, “Combined pulse shape and pulse position modulation for high data rate transmissions in ultra-wideband communications,” International...
... this paper, a novel hybrid modulation technique called differential amplitude pulse- position modulation (DAPPM) is proposed DAPPM is a combination of pulse- amplitude modulation (PAM) and DPPM The ... Networking However, these techniques require more bandwidth as the maximum symbol length increases Multilevel modulation schemes were introduced in [10, 11] to achieve better bandwidth efficiency at the ... a)7 a 12 13 11 (3) (4) DIFFERENTIAL AMPLITUDE PULSE- POSITION MODULATION DAPPM is a combination of PAM and DPPM Therefore the symbol length and pulse amplitude are varied according to the information...
... data symbols Introduction • Possible approaches include – Pulsewidthmodulation (PWM) – Pulse position modulation (PPM) – Pulse amplitude modulation (PAM) • We will only be considering PAM in these ... of impulse train in transmit filter PAM • Clearly not a practical technique so – Use a practical input pulse shape, then filter to realise the desired output pulse shape – Store a sampled pulse ... k 2π T ) = T k • Substituting f=ω/2π gives the Nyquist pulse shaping criterion ∑ H( f − k T) = T k Nyquist Pulse Shaping • No pulse bandwidth less than 1/2T can satisfy the criterion, eg, T −2/Τ...
... điệu độ rộng xung pwm:(pluse width modulation) Hình 6.26: Khối biến điệu PWM Trước tiên tín hiệu s(t) lấy mẫu giữ để có s1(t) 4/5 biến điệu độ rộng xung pwm:(pluse width modulation) Tín hiệu cưa ... gấp đôi trường hợp trước Nhưng khơng phải vậy, hình 6.24 2/5 biến điệu độ rộng xung pwm:(pluse width modulation) Hình 6.24: PWM phép biến điệu phi tuyến Nếu ta giả sử tín hiệu s(t) biến đổi chậm ... biến điệu độ rộng xung pwm:(pluse width modulation) Hình 6.23: Biến điệu PWM Cũng trường hợp FM, PWM phép biến điệu phi tuyến Xem thí...
... biến điệu mã xung - pcm ( pulse code modulation ) Sự lượng tử hố làm tròn mức dùng làm bậc thang giống tín hiệu mong muốn Số mức ... khái niệm ADC Hình 7.17 biểu diễn s(t) dạng sóng PCM bit bit 2/3 biến điệu mã xung - pcm ( pulse code modulation ) Hình 7.17:PCM Mộtxung dương biểu diễn cho bit xung Zero biểu diễn bit Hoàn điệu...
... (delta pulse code modulatuion), PCM vi phân, biến điệu mã hố xung vi phân thích nghi ADPCM (adaptive differential pulse code modulation) 5/9 kỹ thuật biến điệu luân phiên (alternate modulation techniques) ... chiếu (thường zero) 3/9 kỹ thuật biến điệu luân phiên (alternate modulation techniques) BIẾN ĐIỆU DELTA THÍCH NGHI (adaptive delta modulation) Ta trình bày cỡ bước thích hợp để sử dụng biến điệu ... kỹ thuật biến điệu luân phiên (alternate modulation techniques) - delta Tại thời điểm lấy mẫu, dạng sóng lượng tử hố tăng giảm số delta Hình 7.24...
... không vượt hai quỹ đạo tròn giới hạn Điều chế vector không gian cải biến (Modified space vector modulation) Một số tác giả đưa phương pháp điều chế vector không gian cải biến [55],[56] đó, trình...
... 1.1.3 Modulation schemes for Domestic Power line communication Typical modulation schemes used in power line communication can be divided into two types ofmodulation schemes, namely Narrow-band modulation ... Processing) technology, however, the use of complex modulationtechniques can now provide broadband networking applications on a domestic power line Modulation refers to the process of transmitting ... & Zimmerman 2000) 2I 1.3 llIustration ofNarrow-band modulationtechniques (Downey & Sutterlin 1999) 23 1.4 llIustration ofSpread Spectrum techniques (Downey & Sutterlin, 1999) 23 1.5 llIustration...
... are variations of pulse amplitude, pulse width, and pulse position Figure 1.3 shows several baseband modulation waveforms The first one is the nonreturn to zero-level (NRZ-L) modulation which ... Thus amplitude modulation, frequency modulation, and phase modulation are the three basic modulation methods in passband modulation Figure 1.4 shows three basic binary carrier modulations They ... chapters of digital modulationtechniques covering either certain types of modulation, or only principles of the techniques There are also a few books specializing in certain modulations This book...
... in a composite pulse The presence of individual orthogonal pulses in the composite pulse is decided by on-off keying, (i.e., pulse is present for one and is absent for zero) Since pulses are orthogonal, ... of 1st-, 2nd-, and 3rd-order pulses (k) where T p is the width of pulses, wn is the nth-order pulses from the kth user If all users use the same set of orthogonal pulses, n takes any value from ... one another When a pulse overlaps with itself, it is called interpulse interference (IPI) or self-interference and when pulse interferes with other pulses, it is called multipulse interference...
... standard’ techniques for cardiac output measurement, such as aortic electromagnetic or ultrasound transit time flowmetry, are highly invasive and cannot be used in patients Clinically available techniques ... the two techniques was observed in only three cases [10] The open boxes and vertical bars indicate mean and standard deviation, respectively (differential pressure pneumotachometer) and a pulse ... Care June 2002 Vol No Berton and Cholley Pulse contour cardiac output Figure The first attempt to determine stroke volume from the shape of the arterial pulse curve can be tracked as far back as...
... function (LSF) is the derivative of the edge response The width of the LSF is usually expressed as the Full -Width- at-Half-Maximum (FWHM) The width of the edge response is usually quoted by the 10% ... in Fig 25-3, the line spread Chapter 25- Special Imaging Techniques a Line Spread Function (LSF) 427 b Edge Response 90% 50% 10% Full Width at Half Maximum (FWHM) 10% to 90% Edge response FIGURE ... single number, we can ignore the shape of the PSF and simply measure its width The most common way to specify this is by the Full -Width- at-Half-Maximum (FWHM) value For example, all the PSFs in (a)...