• Journal of Power Electronics
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• 제9권3호
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• pp.343-353
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• 2009

In this paper, a nonlinear controller is proposed for Doubly-Fed Induction Machine (DFIM) drives. The nonlinear controller is designed based on an adaptive backstepping control technique, using a fifth order model of an induction machine in the synchronous d & q axis rotating reference frame, whose d axis coincides with the space voltage vector of the main AC supply, and using the rotor current and stator flux components as state variables. The nonlinear controller can perfectly track the torque reference signal measured in the stator terminals under the condition of unity power factor regulation, in spite of the stator and rotor resistance variations. In order to make the drive system capable of operating in the motoring and generating modes below and above the synchronous speed, two level Space-Vector PWM (SV-PWM) back-to-back voltage source inverters are employed in the rotor circuit. It is confirmed through computer simulation results that the proposed control approach is effective and valid.

• Journal of the Semiconductor & Display Technology
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• 제3권1호
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• pp.21-26
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• 2004

Recently with the development of power switching device and DSP which has peripheral devices to control AC servo system, the servo technology has met a new development opportunity. Those things make it possible to reduce the time of developing a AC servo system. Fixed point DSP such as TMS320F240x, and TMS320F28x series have a disadvantage in calculating floating number where TMS320C32 or TMS320C31 are floating point DSP. However they usually become a complex hardware system to implement the AC servo system and it increases the cost. In this study, a DSP based AC servo system with a 3-phase PMSM is proposed. The newly produced DSP TMX320F28l2-version C which has the performance of fast speed, 150MIPS, and a rich peripheral interface such as a 12bit high speed AD converter, QEP(Quadrature Encoder Pulse) circuit, PDPINT(Power Drive Protect Interrupt), SVPWM module and dead time module are used. This paper presents a method to overcome fixed point calculating using scaling all parameters. Also space vector pulse width modulation (SVPWM) using off-set voltage and a digital PI control are implemented to the servo system.

• Proceedings of the KIEE Conference
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.260-262
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• 1998

A new method of induction motor drive, which requires not shaft encoder, is presented. This system has both torque and speed controls that are performed by vector control. The scheme is on the basis of a rotor flux speed control, which is performed by torque producing current and rotor flux, derived from the stator voltages and currents. But, there is a problem with respect to the calculated rotor flux vector, which is an integrating operation by which the rotor induced voltage is converted into the rotor flux. The calculated rotor flux does not work so that it is unstable in initial operation, as motor speed approaches zero. For the proposed rotor flux estimator, a lag circuit is employed, to which both the motor-induced voltage and rotor flux command are imposed, and it is possible to calculate even a low frequency down to standstill. We show the validity of the proposed control method through several computer simulations.

• Proceedings of the KIEE Conference
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.693-695
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• 2000

Wide operating range and speed control is needed for wind power generating and a Doubly Fed Induction Generator(DFIG) has good adaptivity for that purpose. This paper deals with power and power factor control using the Grid connected DFIG in the wide speed regions, by controlling frequency and voltage fed to the rotor. Power flow of the DFIG and steady-state algebraic equations of the equivalent circuit are analyzed. For a normal operating region, in which the generator ratings were not exceeded, the rotor current was either less than or equal to the rated value. Accordingly, the optimal power factor can be selected relative to the permissible rated current at the rotor coil which controls the magnitude of the injected rotor voltage to the rotor according to a given rotor frequency.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1528-1538
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• 2018

In this paper, configuration of $1-{\phi}$ seven-level boost DC-link cascade based reversing voltage multilevel inverter (BDCLCRV MLI) is proposed for uninterrupted power supply (UPS) applications. It consists of three level boost converter, level generation unit and full bridge circuit for polarity generation. When compared with conventional boost cascaded H-bridge MLI configurations, the proposed system results in reduction of DC sources, reduced power switches and gate drive requirements. Inverter switching is accomplished by providing appropriate switching angles that is generated by any optimization switching angle techniques. Here, round modulation control (RMC) method is taken as the optimization method and switching angles are derived and the same is compared with various switching angles methods i.e., equal-phase (EP) method, and half-equal-phase (HEP) method which results in improved quality of obtained AC power with lowest total harmonic distortion (THD). Reduction in DC sources and switch count makes the system more cost effective. A simulation and prototype model of $1-{\phi}$ seven-level BDCLCRV MLI system is developed and its performance is analyzed for various operating conditions.

• Proceedings of the KIEE Conference
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.336-338
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• 1996

Inverter is classified into voltage source and current source by the circuit's configuration. VSI (voltage source inverter) has the excellent generality, economical effects and high power-factors. CSI (current source inverter) is proper to frequent acceleration and deceleration of induction motor, the energy recovering accomplished to ac power line without any other device. But CSI inverter have some troubles such that the numbers of components are increased and the circuits are complicated. To solve these problems, a new inverter is proposed in this paper. This method gives protection of inverters when appears both an instantaneous load-open circuits and an instantaneous load-short circuits, and it has the both merits of both VSI and CSI.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• 제5권3호
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• pp.127-137
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• 2012

In this paper, method using electric braking from stop area to high-speed area was presented in order to improve air-brake. And electric braking method can be improved environmental problems, efficiency, economy, etc. Method for electrical complete braking are two ways that method of inserting series resistance between the motor and the inverter, and method of inverter output voltage increase. In this paper, use series resistance insert method because economical and easy to apply. In addition, Series resistor is used short circuit method for reduce the power loss. In improved efficiency and the laboratory environment for secure braking, resistance insert method and inverter output voltage increase method showed same characteristics in all areas.

• JSTS:Journal of Semiconductor Technology and Science
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• 제4권4호
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• pp.280-285
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• 2004

In this paper, a 9-bit analog-to-digital converter (ADC) is designed for optical disk drive (ODD) servo applications. In the ADC, the circuit technique to increase the operating range of the sample-and-hold amplifier is proposed, which can process the wide-varying input common-mode range. The algorithmic ADC structure is chosen so that the area can be significantly reduced, which is suitable for SoC integration. The ADC is fabricated in a 0.18-$\mu\textrm{m} $ CMOS 1P5M technology. Measurement results of the ADC show that SNDR is 51.5dB for the sampling rate of 6.5MS/s. The power dissipation is 36.3mW for a single supply voltage of 3.3V.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1867-1870
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• 2003

The analysis and simulation are the method to study the behavior, response, and specification of the driver device. This paper proposes brushless DC drive which using the vector control technique. The encoder is used detect the rotor position and decode to Three-phase step signal. The step signal is modulated with triangle signal and change to the pulse width modulation (PWM) signal. The PWM signal is used for control the input power of the motor based on the vector control technique. The experimental results of the driver circuit and motor response performed under the following condition: as the motor was started, change the load torque, and vary the supply voltage. The experimental performs with a dynamometer and the test results are compared to the simulation method is the same result.

• Proceedings of the KIEE Conference
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.537-539
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• 1996

In this paper, a design method of the phase shift ZVS-PWM converter is proposed to minimize the volume and increase the efficiency. The trade-offs of switching frequency, efficiency vs volume and ZVS range vs efficiency is also presented. The simulation of the designed converter is performed using the P-SPICE in which a phase-shift controller is proposed. For minimization of the converter volume, switching frequency is selected 100kHz, a simple drive circuit and single auxiliary supply are applied. In consideration of efficiency and load condition, ZVS range is decided from 50% to full load. A 28V, 1Kwatt prototype converter, of which the switch is MOSFET is made, verified the performance.