Simple Analog Control Research Articles

A load impedance emulation active interface for piezoelectric vibration energy harvesters

A single stage active AC/DC electronic interface able to emulate the optimal load impedance of a Resonant Piezoelectric Vibration Energy Harvester (RPVEH) is proposed. As theoretically shown, unlike an electronic interface that emulates an optimal load generator, an interface that emulates an optimal load impedance does not require adaptation to the acceleration of input vibrations. This allows the use of a very simple control, avoiding the implementation of Maximum Power Point Tracking algorithms that require lossy microcontrollers. Thus, the proposed interface is equipped with a simple analog controller allowing the RPVEH to work in its Maximum Power Point in both steady-state and variable conditions of vibrations, without recurring to multivariable perturbative approaches, as it happens for the most of single stage AC/DC interfaces proposed in the literature. The absence of perturbative techniques allows a significant improvement of both stationary and dynamic performances. Experimental tests of a prototype of the proposed interface confirm the theoretical findings and the predicted behavior.

Variable-Width Hysteretic Analog Control for QSW-ZVS and TCM Source/Sink Converters

This paper proposes a very simple analog control for quasi-square-wave zero voltage switching (QSW-ZVS) and triangular current mode bidirectional converters. The proposed circuit controls the inductance current, thanks to the use of a variable-width hysteretic current mode control. The upper and lower bounds of the hysteretic band are clamped to ensure QSW-ZVS operation with a single current command and independently from power flow direction. This enables the control to achieve a seamless transition between source and sink modes. The advantages and disadvantages of the proposed analog control are analyzed and two different power converters are built to demonstrate the validity of this solution: a 50 W, 48 to 24 V bidirectional buck converter and a 100 W, 24 to 48 V bidirectional boost converter.

An Improved Interleaved Boost Converter With PSO-Based Optimal Type-III Controller

This paper presents an improved interleaved boost converter (IBC) with optimal Type-III controller by utilizing voltage mode control. Due to the presence of several power switches in parallel path, the degree of freedom has been increased in IBC. Also, the IBC produces lower output voltage ripples, so the size and losses of the output filter can significantly be reduced compared with conventional BC. But due to the nonminimum phase problem of IBC, closed-loop bandwidth is restricted that causes slower converter dynamics. It is difficult for the conventional proportional-integral-differential controller to exhibit good performance with line, load changes, and parametric uncertainty. So an optimal Type-III controller is designed and implemented for achieving better closed-loop dynamic performance and stability. Initially, controller parameters have been designed by using the classical “k-factor” method, and then particle swarm optimization-based optimal Type-III controller is developed for the proposed IBC. The comparative closed-loop performances of BC and IBC with classical and optimal Type-III controllers have been presented. The proposed control scheme by utilizing the optimized Type-III controller in IBC is newly introduced in this paper and has not been reported earlier. The overall control circuit diagram using voltage-mode controlled two-phase IBC has been implemented by simple analog control circuit and the cost of complete experimental setup is very cheap. Simulation and experimental results have been produced to show the efficacy of the proposed converter control system.

An offset cancellation technique for comparators using body-voltage trimming

A novel offset cancellation technique based on body-voltage trimming is presented to be used in the comparators employed in high-speed analog-to-digital converters (ADCs) such as Flash ADCs. The proposed offset cancellation is achieved by body-voltage adjustment using a low-power simple analog control feedback circuit without any additional capacitive loading at the comparator output or complicated digital calibration scheme. The accuracy of the proposed technique is higher than its digital calibration counterparts due to its analog nature. Simulation results in a 1.8 V 0.18 μm CMOS technology show that using the proposed technique the standard deviation of the comparator offset is significantly reduced from 36.2 to 7.1 mV operating at 1 GHz with only 32 μW of power dissipation in the offset cancellation circuit.

A Simple Analog BLDC Drive Control for Electro-Mechanical Energy Storage System

Electro-Mechanical Batteries have important advantages compared with chemical batteries. High speed, slotless, external rotor, BLDC machines are used in these systems as Motor/Generator. It is used for converting the electrical energy to the rotational kinetic energy and vice versa. A bidirectional, variable frequency, variable amplitude, three phase BLDC drive needs for its operation in charge and discharge state. Generally, microprocessors are used for their control. But they are complex and expensive. In this paper, limitations, considerations, design and construction of a simple analog control circuit presents. Experimental results are verifying the design proses

Design of Complex BPF with Automatic Digital Tuning Circuit for Low-IF Receivers

This paper describes the architecture and implementations of an automatic digital tuning circuit for a complex bandpass filter (BPF) in a low-power and low-cost transceiver for applications such as personal authentication and wireless sensor network systems. The architectural design analysis demonstrates that an active RC filter in a low-IF architecture can be at least 47.7% smaller in area than a conventional gm-C filter; in addition, it features a simple implementation of an associated tuning circuit. The principle of simultaneous tuning of both the center frequency and bandwidth through calibration of a capacitor array is illustrated as based on an analysis of filter characteristics, and a scalable automatic digital tuning circuit with simple analog blocks and control logic having only 835 gates is introduced. The developed capacitor tuning technique can achieve a tuning error of less than ±3.5% and lower a peaking in the passband filter characteristics. An experimental complex BPF using 0.18µm CMOS technology can successfully reduce the tuning error from an initial value of -20% to less than ±2.5% after tuning. The filter block dimensions are 1.22mm × 1.01mm; and in measurement results of the developed complex BPF with the automatic digital tuning circuit, current consumption is 705µA and the image rejection ratio is 40.3dB. Complete evaluation of the BPF indicates that this technique can be applied to low-power, low-cost transceivers.

A Simple Analog Controller for Single-Phase Half-Bridge Rectifier

A simple analog controller is proposed for the single-phase half-bridge pulsewidth modulation rectifier to maintain near unity power factor at the input and balance the voltages across each half of the dc bus. The controller works in the principle of constant-frequency current programmed control. The required gating pulses are generated by comparing the input current with a linear and bipolar carrier without sensing the input voltage. Two voltage controllers and a single reset-integrator are used to generate the carrier. All the necessary control operations are performed without using any phase locked loop, multiplier, and/or divider circuits. Resistor based sensors are used to measure the voltages across two halves of the dc bus and the input current. The controller can be fabricated as a single integrated circuit. The averaged small signal models and all the necessary design equations are provided. The condition of stability against subharmonic oscillation is analyzed. Calculation of switching and conduction losses is presented. The control concept is validated through simulation and also experimentally on an 800-W half-bridge rectifier. Experimental results are presented for ac-dc application, and also for ac-dc-ac application with both linear and nonlinear loads at two different output fundamental frequencies (50 and 60Hz)

Harmonic reducer converter

A new strategy to accomplish low-frequency Regulation EN 61000-3-2 at system level is proposed in this paper. By means of a simple converter, connected in parallel with the loads, the harmonic currents generated by them are greatly reduced, it being unnecessary to include additional power-factor-correction converters. This approach is based on the well-known parallel active power filters, but the difference is that it is placed on the DC side. Its position, at the rectified line voltage, produces some important advantages such as a simple power stage, a simple analog control, and flexibility in the design of the system. Moreover, this converter features high efficiency and small size. The experimental results show the benefits of this solution.

A Simple Analog Controller for Switched Reluctance Motor

This paper presents a simple analog scheme for speed control of switched reluctance motor (SRM). It is designed to operate with minimum number of switching devices. The scheme makes use of signals of rotor position, speed, and current in the closed loop feedback control. The analog controller is tested for four quadrant operation of the drive. Use of off-the-shelf electronic components makes the controller simple and economical. The test results are presented for a 4kW, 4-phase, 1500 rpm 8/6 pole SR motor. The proposed scheme is shown to be simple, cost effective and useful for low power applications.

Enhanced Low Frequency Transmission Loss of Light Weight Trim Panels Using PZT Inertial Actuators

One method of enhancing the low frequency transmission loss of noise into the cabin of a propeller driven aircraft or helicopter is to replace selected sections of the interior trim with stiff, ultra light panels that are driven with PZT inertial actuators. Given the proper control signals, the panels can be driven by the actuators such that their net volume velocity is minimized. Experiments are described that measure the sound transmission loss for a soft mounted, double layer corrugated aluminum panel driven by four actuators consisting of symmetrically-mounted, cantilevered beams with end masses driven by unimorph piezoelectric elements. A feedback control system is designed by serially connecting three Tow-Thomas biquad filters which are based on a Motorola LF347N integrated circuit design. Using this simple analog controller with the panel’s accelerations as an input, experimental results show that the inertial actuators mounted at the center of the panel produce up to 13 dB improvement in both vibration reduction and noise transmission loss of the panel.

Frequency-locked light scattering: real-time Doppler velocimetry with closed-loop feedback control

Real-time measurement capability of a frequency-modulated filtered light-scattering- (FM FLS) Doppler velocimeter has been demonstrated. Doppler-shifted light from a frequency-modulated Ti:sapphire laser scattered from a supersonic flow is imaged through a potassium vapor cell and is detected by FM spectroscopy. The FM signal is used in closed-loop feedback control of the laser frequency to lock the Doppler-shifted scattered light to the resonance frequency of the filter. The difference between the filter resonance frequency and the laser frequency when the scattered light is frequency locked to the filter resonance is the flow-induced Doppler shift. Changes in flow velocity are tracked by changes in laser frequency, which is subsequently measured to obtain the Doppler shift. The frequency-locking capability of the technique was achieved with use of a simple analog controller. The random Doppler shift measurement errors (2varsigma) were approximately 20 MHz, which correspond to velocity measurement errors for the real-time measurement of less than 3% in a 10-Hz bandwidth.

Three-dimensional tracking using qualitative bionic sonar

A sonar-driven robot, ROBAT 3D , has been implemented to track an object moving in three dimensions using qualitative interpretation of the sonar signals. ROBAT 3D is equipped with a sonar system consisting of five identical transducers configured in the form of a cross. The center transducer emits an acoustic pulse and the echoes are detected by pairs of receivers that flank the transmitter horizontally and vertically. The vertically-oriented receivers are used to control the pitch while those oriented horizontally control the yaw. ROBAT 3D is driven by four air jets that provide lateral forces that direct the heading toward the object. Two bits of information are extracted from each emission, one for pitch correction and the other for yaw correction. The correction is determined by which sensor in a pair first detects the echo. That sensor actuates an air valve supplying the contralateral jet to correct the heading. The range to the object can be determined from the echo time-of-flight. This simple nonlinear analog control system is very fast and can track an object that has an angular velocity upto π /2 rad /s. A trade-off exists between the size of a limit cycle oscillation and the bandwith of the system, determined by the thrust of the jets and the delay in the sonar sensing.

A control system for multi-stage flash desalination plants

A system of simple analog control loops has been investigated experimentally in a 6-stage flashing test unit, which is aimed to automate the plant operation and to improve the distillation process within any required operating condition. The control circuit includes the control of liquid levels and temperatures in the first and last flashing chamber, adjusting automatically the amount of steam to the brine heater, and the brine flow rates in both the heat rejection and the heat recovery section. Using this system, the load can be changed more easily and quickly than by manual operation, which is an important factor for dual purpose plant coupling. Experiments have been carried out and simulated with a modified. form of a digital computer code published, by ORNL (ref. 3). Calculated and experimental results have been found to agree with one another very closely. The computer program was also applied to a MSF plant design with a higher number of stages. One of the main results is that, by decreasing the load, interstage blow-through can occur in the middle stages of the plant, even if the liquid levels in the first and in the last stage are kept constant. It is shown that the presence of weirs in the flashing chambers reduces this tendency.