Sirichai Tammaruckwattana

A novel resolver-to-DC converter based on OTA-based inverse-sine function circuit

A new technique for realizing the resolver-to-DC converter using the OTA-based inverse-sine function circuit is presented. The proposed converter comprises the demodulator, absolute detector, minimum detector, plusmn unity-gain amplifier, controlled signal logic circuit, and OTA-based inverse-sine function circuit. The output voltage is linearly proportional to the resolver angle with maximum absolute error of about 0.195%, which is less than the error from the conventional resolver-to-DC converter based on the similar OTA-based inverse-sine function circuit. PSPICE simulation and experimental results verifying the performances of the proposed circuit are in close agreement with the expected values.

Experimental Assessment with Wind Turbine Emulator of Variable-Speed Wind Power Generation System using Boost Chopper Circuit of Permanent Magnet Synchronous Generator

This paper presents experimental results and its assessment of a variable-speed wind power generation system (VSWPGS) using permanent magnet synchronous generator (PMSG) and boost chopper circuit (BCC). Experimental results are obtained by a test bench with a wind turbine emulator (WTE). WTE reproduces the behaviors of a windmill by using servo motor drives. The mechanical torque references to drive the servo motor are calculated from the windmill wing profile, wind velocity, and windmill rotational speed. VSWPGS using PMSG and BCC has three speed control modes for the level of wind velocity to control the rotational speed of the wind turbine. The control mode for low wind velocity regulates an armature current of generator with BCC. The control mode for middle wind velocity regulates a DC link voltage with a vector-controlled inverter. The control mode for high wind velocity regulates a pitch angle of the wind turbine with a pitch angle control system. The hybrid of three control modes extends the variable-speed range. BCC simplifies the maintenance of VSWPGS while improving reliability. In addition, VSWPGS using PMSG and BCC saves cost compared with VSWPGS using a PWM converter.

Modeling and simulation of wind power generation system using diode bridge rectification circuit for converter

This paper presents the variable-speed permanent magnet synchronous generator wind power system using the diode bridge rectification circuit for the converter. The wind speed model which simulates the actual wind is investigated, and it is realized as the Simulink model. The parameters of the permanent magnet synchronous generator are measured and the generator torque characteristic using the obtained parameters is calculated. The wind turbine torque characteristic and the range of the wind speed in which the wind power system can operate is clarified by comparing with boost converter method and PWM converter method. The diode bridge rectification circuit system simplifies the maintenance and improves the reliability and reduces the cost in compare with boost converter method and PWM converter method.

Bitmap picture to toolpaths converter for NC machine

A simple method to create the toolpaths from bitmap picture of the workpiece for NC machine is described in this article. Halftone process is used to reproduce a continuous tone picture to binary tone picture for making a prototype picture. The obtained two dimensions picture with halftone process is employed to create the toolpaths of the sample workpiece. The workpiece dimension can be scaled to limitation of work table of NC machine by user with independent of picture resolution. The toolpaths are created as cutter location data (CL) that can be imported to postprocessor for NC machine. The proposed method is developed using visual C# programming language under window environment. Experimental implementation exhibits that the proposed bitmap picture to toolpath converter is efficient for the postprocessor to generate machine command for sculpture the workpiece from bitmap picture.