Sawai Pongswatd

Simple VCO with negative voltage-frequency relation

A simple voltage controlled oscillator (VCO) with negative voltage-frequency (V-F) relation is presented in this paper. The realization technique is based on the use of commercial available devices to generate tunable sawtooth and square wave signals. Decreasing the control voltage linearly increases the output oscillation frequency. The proposed VCO consists of operational transconductance amplifiers (OTAs) and an RS Flip Flop. Experimental results showing the circuit performances are agreed with the expected values. The usefulness of the proposed circuit is demonstrated through application example with reducing the output ripple waveforms of a buck converter.

Application of GD 3 in value engineering for plastic-part design

This paper presents the technique in way engineering value that comes to apply for designing of product plastic. The technique analyzes the data of designing by GD3 and measures defensive problem in advance of engineering value. Consequently, the technique can prevent the problem and control the designing relate to engineering value before build a mold for product. For acquire knowledge give with the work and can design the product that can have picture stability. Moreover, This technique can decrease material loss, time operation and inventory.

Synthesis and analysis of a multiple-input parallel SC DC-DC converter

As compared with parallel converters employing buck converters or boost converters, the analysis of multiple-input parallel switched-capacitor (SC) DC-DC converters is not sufficient. In this paper, a multiple-input parallel DC-DC converter designed by using SC techniques is proposed for mobile back-lighting applications, and handy theoretical formulas are given concerning the power efficiency and equivalent circuit. The proposed parallel converter consists of two different kinds of converter blocks: 1. a 1.5× step-up SC DC-DC converter employing an input voltage from a lithium battery and 2. a novel step-up converter employing an input voltage from solar cells. The proposed converter can offer the output voltage for display back-lighting from solar energy, because the proposed step-up converter can achieve not only a large step-up conversion ratio but also a wide input range. Hence, the proposed converter will enable us to realize a long battery life, reduction of heat, and so on. Furthermore, derived theoretical formulas will be helpful to estimate circuit characteristics, because theoretical results agree well with SPICE simulation results. The validity of circuit design is confirmed by simulations and experiments.

Digital Technique to Generate Variable and Multiple PWM Signals

In this paper, we present a digital technique to generate pulse width modulation (PWM) signal using counters, comparators, and latching circuits implemented by Verilog HDL program based on FPGA. The proposed technique can simultaneously generate variable and multiple PWM outputs with parallel processing. Setting each reference-input signal can independently and easily vary the pulse width of each generated signal. The FPGA-based implementation can minimize the size of hardware. The communication can be easily done via a personnel computer. Application example in the design of the proposed technique as the parallel processing is also included.

Integration of WirelessHART and ISA100.11a field devices into condition monitoring system for starting IIoT implementation

This paper presents a technique to integrate wireless field devices using WirelessHART and ISA100.11a technologies into a condition monitoring system based on Wonderware InTouch software. The proposed integration brings the data from a field site with digital multi-device networking for automatic data collection to support the condition monitoring of instruments or smart connected equipment in preparation of the Industrial Internet of Things (IIoT) implementation. Data including process variables and diagnostics from WirelessHART and ISA100.11a devices are buffered and mapped into Modbus/TCP registers for real-time monitoring at the operator workstation. Experimental results confirm that the proposed integration functions correctly.

A Multiple-Input SC DC-DC Converter with Battery Charge Process

Aimed at a backlighting application, a multiple-input switched-capacitor (SC) DC-DC converter with battery charge process is proposed in this paper. Unlike conventional SC power converters such as a Dickson-type converter, etc., the proposed converter drives some LEDs by converting energy from solar cells when solar cells offer enough energy. Furthermore, the proposed converter can charge a lithium battery when an output load is light. Hence, the proposed converter enables us to realize long battery runtime. The validity of circuit design is confirmed by theoretical analyses, simulations, and experiments. The derived theoretical formulas will be helpful to estimate circuit characteristics, because theoretical results agree well with SPICE simulation results.

Design of a Step-Down AC-DC Converter for Energy Harvesting System Using Vibration-Based Energy

To realize battery-free operation employing energy harvesting, a step-down switched-capacitor-based converter has been used as a vibration-to-electricity converter. In this paper, to improve power efficiency, a step-down ACDC converter realizing 1/N (N=2,3,... ) conversion modes is designed by using switched-capacitor techniques. Although conventional converters offer an output by regulating the stored energy in a big capacitor, the proposed converter generates the output by performing AC-DC conversion. Thus, the proposed converter can improve power efficiency. Concerning the power efficiency, the effectiveness of the proposed converter is clarified by theoretical analysis. Furthermore, the validity of the circuit design is confirmed by simulations and experiments.

Accurate Dual Slope Analog-to-Digital Converter Using Bootstrap Circuit

This paper presents a simple and inexpensive implementation of the accurate dual slope analog-to-digital converter (ADC). The proposed technique with positive reference voltage takes advantages of a bootstrap circuit to function as a precise noninverting/ inverting integrator. To achieve the constant reference voltage during integrating analog input voltage interval, a sample/hold (S/H) circuit is employed. Experimental results are given to confirm the operation of the proposed ADC.

The technique to generate firing signal of converter for linear dc output

The firing angle adjustment of ac-dc converter that adjust firing angle proportional to control signal. The dc output voltage is not linear. This paper presents the technique to generate the firing signal for ac-dc converter which has linear dc output voltage. This technique decoded the arccosine value as binary data and save in ROM, before compare with control signal. All digital circuits and ROM were constructed using field programmable gate array (FPGA) and Verilog Hardware Description Language (Verilog HDL) so that the proposed technique has small size and ease of implementation. The experimental results show the dc output voltage and output waveform that agree with the design. Moreover, this technique can be applied to multi-output for dual converter and 3- phase system.

Integration of wireless HART network system into SCADA software for operation & management

This paper describes the technique to integrate HART field devices into SCADA (Supervisory Control and Data Acquisition) system. Wire HART field device is connected to WirelessHART adapter (THUM) and WirelessHART device are assigned act as RTU(Remote Terminal Unit) in SCADA system. In system, THUM and WirelessHART device communicate to WirelessHART gateway that collects their data and send to master station with Modbus/TCP. The paper presents the practices to install and configure the THUM with control valve wire HART device, WirelessHART transmitter, tags assignment, and so on that focus for HART parameters mapping in order to device operation and management. Effectiveness of the proposed system integration is verified by simulation and experimental results. Moreover, the technique can be applied in existing plants or in new project to support end-users to quickly and easily gain the benefits of device diagnostic and decision support for operation and management.