Seven Level Voltage Source Converter Based Static Synchronous Compensator with a Constant DC-Link Voltage

Flexible alternating current transmission system (FACTS) controllers are important to enhance the quality of power in power systems. The stability of a system is achieved via a FACTS device (a Static Synchronous Compensator (STATCOM)). This paper aims to control the losses in the transmission system during peak energy demand circumstances with minimal losses in the economical and functional efficiency of the system. The STATCOM operation of a seven level voltage source converter (VSC) with binary-weighted transformers is proposed for controlling the reactive power variations and terminal voltage changes at dynamic circumstances in the transmission system. The STATCOM is operated at 132 kV and is a 50 Hz AC system with a single DC-Link capacitance and two VSC power circuits. Each VSC circuit consists of three H-bridges with specific switching angle control in order to achieve low total harmonic distortion at the fundamental frequency. The coupled control circuit phenomenon is imperative for computing the switching angle for a stable performance. The dynamic functional improvement efficiency is harvested with a minimum number of switches and transformers used in high voltage and high-power applications. The number of switches, transformers, and capacitors for 132 kV are optimized with a proposed STATCOM operation in seven level VSC with binary-weighted transformers. The simulated results prove that the proposed model significantly improved system performance and stability.

A 1.8 V high-speed 8-bit hybrid DAC with integrated rail-to-rail buffer amplifier in CMOS 180 nm

Purpose The purpose of this paper is to present the performance of an 8-bit hybrid DAC which is suitable for wireless application or part of a built-in test block for ADC. The hybrid architecture used is the combination of thermometer coding and binary-weighted resistor architectures. Design/methodology/approach The conventional DAC topology performance tends to degrade at high-resolution applications. A hybrid topology, which combines an equal number of bits of thermometer coding and binary-weighted resistor architectures operating at higher sampling frequency, was proposed in this work. The die was fabricated in 180 nm CMOS process technology with a supplied voltage of 1.8 V. Findings Measured results showed that the DNL and INL errors are within −1 to +1 LSB and −0.9 to +0.9 LSB, respectively for the input range of 0.9 V at the clock rate of 200 MHz, and this DAC was proven monotonic. This 0.068 mm2 DAC consumed 12.6 mW for the data conversion. Originality/value This paper is of value in showing the equal division of bits from thermometer coding and binary-weighted resistor architectures provides smaller die size and enhances the performance of hybrid DAC, in terms of linearity, which are DNL and INL errors and guarantees monotonicity at higher sampling frequency.

Further Improvement of Customized Vibration Generator for Machine–Human Feedbacks with the Help of Resonant Networks

Modern industrial, household and other equipment include sophisticated power mechanisms and complicated control solutions and require tighter human–machine–human interaction, forming the structures known as cyber–physical–human systems. Their significant parts are human–machine command links and machine–human feedbacks. Such systems are found in medicine, for example, in orthopedics, where they are important for operation and functional abilities of orthopedic devices—smart wheelchairs, verticalizers, prosthesis, rehabilitation units, etc. The mentioned feedbacks may be implemented based on the haptic perceptions that require vibration actuators. In orthopedics, such actuators can also be used for diagnostic purposes. This research brings forward the idea of the use of resonant operation of the driver of vibration actuator. The corresponding driver has been built and experimentally tested. It has been found that (1) the point of maximal current is actually defined by the resonant frequency, (2) change of the capacitance allows shifting of the point of maximal current output and (3) damping factors make the above-described effect less obvious. Further development of the proposed idea requires a comprehensive comparison of four-quadrant and two-quadrant schemes in this application and development of a real-time programmable capacitor pack consisting of several binary weighted capacitors and a commutating circuit, which is installable to these schemes.