Among various satellite actuators, magnetic torquers have been widely equipped for stabilization and attitude control of small satellites. Although magnetorquers are generally used with other actuators, such as moment...
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With the rapid change in technology, the goal of designing portable electronic product focus on longer battery lifetime. Thus, the low overshoot performance in DC-DC buck converter becomes more important. When the swi...
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ISBN:
(数字)9781665470506
ISBN:
(纸本)9781665470506
With the rapid change in technology, the goal of designing portable electronic product focus on longer battery lifetime. Thus, the low overshoot performance in DC-DC buck converter becomes more important. When the switching DC-DC buck converter withstands the large changes from the load, the output voltage will be instantaneously unstable due to insufficient or excessive stored energy in the capacitor, especially in the case of severe load changes, it may even cause the damages on the equipment. In this paper, a sawtooth wave generator was applied to improve the charging and discharging characteristics of capacitor. From the results, the sawtooth oscillation waveforms were successfully generated from the changes of load, and the fast transient response is achieved. The recovery time at undershoot and overshoot conditions are 5.3 mu s and 5.8 mu s, respectively.
Linear switched impulsive systems (SIS) are characterized by ordinary differential equations as modes dynamics and state jumps at the switching time instants. The presence of possible jumps in the state makes nontrivi...
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Linear switched impulsive systems (SIS) are characterized by ordinary differential equations as modes dynamics and state jumps at the switching time instants. The presence of possible jumps in the state makes nontrivial the application of classical averaging techniques. In this paper we consider SIS with pulse width modulation (PWM) and we propose an averaged model whose solution approximates the moving average of the SIS solution with an error which decreases with the multiple of the switching period and by decreasing the PWM period. The averaging result requires milder assumptions on the system matrices with respect to those needed by the previous averaging techniques for SIS. The interest of the proposed model is strengthened by the fact that it reduces to the classical averaged model for PWM systems when there are no jumps in the state. The theoretical results are verified through simulations obtained by considering a switched capacitor electrical circuit.(c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://***/licenses/by/4.0/).
In this study, we compared conventional pulse width modulation (PWM) methods for Class-D amplifiers and we proposed a modified PWM pattern for high efficiency and lower common mode voltage. Bipolar PWM and Unipolar PW...
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ISBN:
(纸本)9781665406895;9781665406888
In this study, we compared conventional pulse width modulation (PWM) methods for Class-D amplifiers and we proposed a modified PWM pattern for high efficiency and lower common mode voltage. Bipolar PWM and Unipolar PWM methods are the main switching patterns for Class-D amplifiers. Unipolar PWM is advantageous in terms of doubling effective switching frequency, hence reducing filter size, compared to the Bipolar PWM. On the other hand, common mode performance worsens due to the asymmetrical switching pattern. In this study, we proposed a Modified Unipolar PWM pattern and we demonstrated its advantages in Class-D amplifiers for underwater acoustic applications. Throughout the paper, we presented the analytical loss calculations. The proposed pattern provides an intermediate solution in between Bipolar PWM and Unipolar PWM methods in terms of comparable efficiency and common mode performance. We demonstrated the applicability of the proposed Modified Unipolar PWM switching method and verified its performance through computer simulations and experimental test results.
Cyber-physical systems (CPS) consist of integrated computational and physical components. The dynamics of physical components (e.g., a robot arm) are controlled by actuators via actuation signals. In this work, we ana...
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ISBN:
(纸本)9781939133311
Cyber-physical systems (CPS) consist of integrated computational and physical components. The dynamics of physical components (e.g., a robot arm) are controlled by actuators via actuation signals. In this work, we analyze the extent to which intentional electromagnetic interference (IEMI) allows an attacker to alter the actuation signal to jam or control a class of widely used actuators: those that use pulse width modulation (PWM) to encode actuation data (e.g., rotation angle or speed). A theory of False Actuation Injection (FAI) is developed and experimentally validated with IEMI waveforms of certain frequencies and modulations. Specifically, three attack waveforms, denoted as Block, Block & Rotate, and Full Control, are described that can be utilized by an attacker to block (denial of service) or alter the actuation data encoded in the PWM signal sent by an actuator's legitimate controller. The efficacy of the attack waveforms is evaluated against several PWM-controlled actuators, and it is observed that an attacker can implement denial-of-service attacks on all the tested actuators with Block waveform. Additionally, attackers can take control of servo motors from specific manufacturers (Futaba and HiTec) with reported Block & Rotate, and Full Control waveforms. A coupling model between the attack apparatus and victim PWM-based control system is presented to show that the attacker can utilize magnetic, resonant coupling to mount attacks at an appreciable distance. Indoor and in-flight attacks are demonstrated on the actuators of an unmanned aerial vehicle (UAV), the effects of which are shown to seriously impact the safe operation of said UAV, e.g., change in the flight trajectory. Additionally, the denial of service attacks are demonstrated on other actuators such as DC motors, the rotational speed of which is controlled with PWM, and possible countermeasures (such as optical actuation data transmission) are discussed.
In this work, a new carrier-based pulse width modulation (CPWM) scheme is built for three-to-three phase indirect matrix converter (IMC). In the existing CPWM schemes, the control schemes of the source side converter ...
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In this work, a new carrier-based pulse width modulation (CPWM) scheme is built for three-to-three phase indirect matrix converter (IMC). In the existing CPWM schemes, the control schemes of the source side converter of the IMC are developed based on either sector based complex calculations or over-modulation operation to obtain the required performance. In the new CPWM scheme, the simplified modulation equations for the source side converter of the IMC are proposed which provide the required performance without resorting to the sector based duty cycle calculations or over-modulation operation. The source and load side converter stages of the IMC are modulated with the standard CPWM principles of the conventional inverter and rectifier topologies in the present work. This work also compares the new CPWM scheme with the SVPWM scheme based on the mathematical calculations which proves that the new CPWM scheme requires less mathematical operations as compared to SVPWM scheme. The simulation and experimental results for both modulation schemes are presented which proves that the new CPWM scheme provides the equivalent input and output performances to those of the SVPWM scheme. The control devices DSP (TMS320F28335) and FPGA (Spartan-6) are used to implement the CPWM and SVPWM schemes.
pulse width modulation (PWM) is widely used in different applications. PWM transforms the information in the amplitude of a bounded input signal into the pulsewidth output signal without suffering from quantization n...
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pulse width modulation (PWM) is widely used in different applications. PWM transforms the information in the amplitude of a bounded input signal into the pulsewidth output signal without suffering from quantization noise. The frequency of the output signal is usually constant. In this paper, the new PWM system with frequency changing (PWMFM) is described. In such PWMFM the pulsewidth and also the carrier frequency are changed. Therefore, two independent pieces of information can be simultaneously transmitted over one channel;hence PWM and frequency modulation (FM) are simultaneously used. But such system needs 2 demodulators, one for PWM and the second for FM. PWMFM can be used in the following applications: LED light intensity control via PWM and several LED block switching by FM PWMFM is highly useful in motor speed control applications by PWM and direction of rotation with FM. PWMFM can be used also in a class-D audio amplifier for power control, e.g. coarse by means of FM and fine by PWM. PWMFM can be used for the simultaneous transmission of two independent information between all, mutual combinations of analog and digital circuits. The analog and digital circuits for modulation and demodulation of PWMF signal are described and measuring results are presented in this work.
An interleaved pulse width modulation (PWM) can be employed in a parallel operation of three-phase converters because the interleaved PWM increases the equivalent switching frequency and significantly enhances the out...
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An interleaved pulse width modulation (PWM) can be employed in a parallel operation of three-phase converters because the interleaved PWM increases the equivalent switching frequency and significantly enhances the output current harmonics. However, interleaved voltage pulse patterns provoke a huge circulating current, and a coupled inductor is employed to suppress the circulating current. Therefore, this study aims to improve the harmonics of voltage and current in parallel operation with a coupled inductor. For the aim, the harmonics of the interleaved PWM have been analyzed. Based on the analysis, a new PWM strategy has been devised by modifying the interleaved carrier. The proposed PWM improves the harmonics of voltage and current. However, unintended additional device switching occurs in the proposed method. Accordingly, a cost index (CI) is defined to show the improvement in the harmonics considering the additional device switching. The validity, feasibility, and effectiveness of the proposed method have been demonstrated by using CI. As a result, the computer simulation and experimental results show that the proposed PWM has efficiently improved the harmonics in various modulation indices.
This paper utilises the concept of pulse numbers to provide a new optimal pulse width modulation strategy for permanent magnet synchronous motor operation. The benefits of traditional modulation systems are preserved,...
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Permanent magnet synchronous motor (PMSM) drive traction system has the advantages of high speed, high efficiency and energy saving, which has become the development direction of the next generation of rail transit tr...
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