• Journal of Power Electronics
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• v.10 no.3
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• pp.285-292
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• 2010

This paper presents a current mode integrated control technique (CM-ICT) using a modified voltage space vector modulation (MSVM) for Z-source inverter (ZSI) fed induction motor drives. MSVM provides a better DC voltage boost in the dc-link, a wide range of AC output voltage controllability and a better line harmonic profile. In a voltage mode ICT (VM-ICT), the outer voltage feedback loop alone is designed and it enforces the desired line voltage to the motor drive. An integrated control technique (ICT), with an inner current feedback loop is proposed in this paper for the purpose of line current limiting and soft operation of the drive. The current command generated by the PI controller and limiter in the outer voltage feedback loop, is compared with the actual line current, and the error is processed through the PI controller and a limiter. This limiter ensures that, the voltage control signal to the Z-source inverter is constrained to a safe level. The rise and fall of the control signal voltage are made to be gradual, so as to protect the induction motor drive and the Z-source inverter from transients. The single stage controller arrangement of the proposed CM-ICT offers easier compensation. Analysis, Matlab/Simulink simulations, and experimental results have been presented to validate the proposed technique.

• Journal of Power Electronics
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• v.13 no.5
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• pp.829-840
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• 2013

The modified sinusoidal pulse-width modulation (SPWM) is one of the PWM techniques used in three-phase AC-DC buck converters. The modified SPWM works without the current sensor (the converter is current sensorless), improves production of sinusoidal AC current, enables obtainment of near-unity power factor, and controls output voltage through modulation gain (ranging from 0 to 1). The main problem of the modified SPWM is the huge starting current and voltage (during transient) that results from a large step change from the reference voltage. When the load changes, the output voltage significantly drops (through switching losses and non-ideal converter elements). The single-input single-output (SISO) approach with minor-loop voltage feedback controller presented here overcomes this problem. This approach is created on a theoretical linear model and verified by discrete-model simulation on MATLAB/Simulink. The capability and effectiveness of the SISO approach in compensating start-up current/voltage and in achieving zero steady-state error were tested for transient cases with step-changed load and step-changed reference voltage for linear and non-linear loads. Tests were done to analyze the transient performance against various controller gains. An experiment prototype was also developed for verification.

• Journal of Power Electronics
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• v.15 no.2
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• pp.469-478
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• 2015

In order to promote the application of switched reluctance machines (SRM) in electric vehicles (EVs), the braking torque closed-loop control of a SRM is proposed. A hysteresis current regulator with the soft chopping mode is employed to reduce the switching frequency and switching loss. A torque estimator is designed to estimate the braking torque online and to achieve braking torque feedback. A feed-forward plus saturation compensation torque regulator is designed to decrease the dynamic response time and to improve the steady-state accuracy of the braking torque. The turn-on and turn-off angles are optimized by a genetic algorithm (GA) to reduce the braking torque ripple and to improve the braking energy feedback efficiency. Finally, a simulation model and an experimental platform are built. The simulation and experimental results demonstrate the correctness of the proposed control strategy.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.161-165
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• 2023

This paper designed a voltage feedback driving circuit to compensate for the characteristic deviation of the Active Matrix Organic Light Emitting Diode driving Thin Film Transistor. This paper describes a stable and fast circuit by applying charge sharing and polar stabilization methods. A 12-inch Organic Light Emitting Diode with a Double Wide Ultra eXtended Graphics Array resolution creates a screen distortion problem for line parasitism, and charge sharing and polar stabilization structures were applied to solve the problem. By applying Charge Sharing, all data lines are shorted at the same time and quickly positioned as the average voltage to advance the compensated change time of the gate voltage in the next operation period. A buffer circuit and a current pass circuit were added to lower the Amplifier resistance connected to the line as a polar stabilization method. The advantage of suppressing the Ringing of the driving Thin Film Transistor can be obtained by increasing the stability. As a result, a circuit was designed to supply a stable current to the Organic Light Emitting Diode even if the characteristic deviation of the driving Thin Film Transistor occurs.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.9 s.351
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• pp.23-30
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• 2006

This paper presents a design of a high-efficiency CMOS DC-DC boost converter using a current-sensing feedback method. High-precision current-sensing circuity is incorporated in order to sense the current flowing in the inductor, which determines the switching scheme of the pulse-width modulation. The external components or large chip area for the frequency compensation can be avoided while maintaining the stable operations of the converter. Various input/output voltage levels can be available through the external resistor strings. The designed DC-DC converter is fabricated in a 0.18-um CMOS technology with a thick-gate oxide option. The converter shows the maximum efficiency over 90% for the output voltage of 3.3V and load current larger than 200mA. The load regulation is 1.15% for the load current change of 100mA.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.7
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• pp.1447-1456
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• 2011

In this paper, we propose a T-S fuzzy feedback linearization method for controlling a non-linear system with multi-input, and the method is applied for trajectory tracking control of wheeled mobile robot. First, an error dynamic equation of wheeled mobile robot is represented by a T-S fuzzy model, and then the T-S fuzzy model is transformed to a linear control system through the nonlinear fuzzy coordinate change and the nonlinear state feedback input. Simulation results showed that the trajectory tracking controller by using the proposed multi-input feedback linearization method gives better performance than the trajectory tracking controller by using the PDC(Parallel Distributed Compensation) method for controlling the T-S Fuzzy system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2172-2177
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• 2015

The DF-MZEP-CME (decision feedback - maximum zero-error probability for constant modulus errors) algorithm that makes the probability for constant modulus error (CME) close to zero and employs decision feedback (DF) structures shows more improved performance in channel distortion compensation. However the DF-MZEP-CME algorithm has a computational complexity proportional to a sample size for probability estimation and this property plays a role of an obstacle in practical implementation. In this paper, the gradient of DF-MZEP-CME is proposed to be estimated recursively and shown to solve the computational problem by making the algorithm independent of the sample size. For a sample size N, the conventional method has 10N multiplications but the proposed has only 20 regardless of N. Also the recursive gradient estimation for weight update is kept in continuity from the initial state to the steady state without any error propagation.

• Journal of Biomedical Engineering Research
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• v.27 no.5
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• pp.282-290
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• 2006

We have developed a multi band digital hearing aid algorithm emphasizing feedback cancellation and a hardware module to evaluate the performance of our algorithm. The hearing aids should be able to compensate for individual hearing loss characteristics of hearing impaired person. Thus hearing aids need the function of multi-bands amplification and the capabilities of feedback cancellation that can remove howling caused by acoustic feedback. In this paper, we proposed a digital hearing aid algorithm which has multi-bands compensation using modified discrete cosine transform (MDCT) and can efficiently remove acoustic feedbacks. Moreover, we have developed digital hearing aid hardware module, which can evaluate hearing aid algorithms in real time operation. The developed algorithm and hardware module were verified through computer simulation and clinical tests. Through operational experiments, good performances in real time operation environment and an efficient howling cancellation were also observed. The developed hardware module can operate in stable condition and it is expected to become a good hardware platform for developing hearing aid algorithms.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.337-340
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• 2003

This paper presented practical details about control-loop design and dynamic analysis for a peak current-mode controlled asymmetrical half-bridge(ASHB) do-to-dc converter, Graphical loop gain method is used to design the feedback compensation and analyze the closed-loop performance of ASHB converter. The results of the control design and closed-loop analysis are validated by experiments on a prototype converter.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.553-555
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• 1994

Various nonlinear loads such as diode rectifiers, and phase controlled converters connected to at source cause harmonic pollutions in ac mains. Recently some filters have been proposed to minimize the potential problems. This study describes a method to improve the performances of a voltage source active filter. Two feedback loops are used in the scheme : one for reactive power compensation and the other for harmonic eliminations.