• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1589-1596
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• 2015

A novel control method of a three-phase PWM inverter with LC filter is proposed. The transfer function of LC filter is the same as that of 2nd order low pass filter(2nd LPF) which has a zero damping ratio. A simple method of implementing 2nd LPF with damping ratio is to add resistor to inductor or capacitor of LC filter. In an industrial application, it is not practical to adopt damping resistor because it results in losses being proportional to square of current flowing through resistor. Instead of using damping resistors, the proposed active damping control(ADC) utilizes all pass filter(APF) and considers inherent processing delay of digital controller. The overall transfer function of the proposed method is the same as a 2nd LPF and its damping ratio is also controllable via control variables. Detailed design and implementation of controller is also presented. Experiments are conducted with a 7.5kVA induction motor drive system controlled by PWM converter and inverter. Test waveforms are also presented to verify the proposed LC filter control algorithm.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.944-951
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• 2015

Pulse Width Modulation (PWM) techniques are increasingly employed for PWM inverter fed induction motor drive. Among various popular PWM methods used, Selective Harmonic Elimination PWM (SHEPWM) has been widely accepted for its better harmonic elimination capability. In addition, using SHEPWM, it is also possible to maintain better voltage regulation. Hence, in this paper, an attempt has been made to apply Bacterial Foraging Algorithm (BFA) for solving selective harmonic elimination problem. The problem of voltage harmonic elimination together with output voltage regulation is drafted as an optimization task and the solution is sought through proposed method. For performance comparison of BFA, the results obtained are compared with other techniques such as derivative based Newton-Raphson method, and Genetic Algorithm. From the comparison, it can be observed that BFA based approach yields better results. Further, it provides superior convergence, reduced computational burden, and guaranteed global optima. The simulation results are validated through experimental findings.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.5
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• pp.384-398
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• 1990

This paper compares and shows the characteristics of various PWM strategies used to generate pulse signals of voltage source inverter. We designed the inverter using PTR and constituted the variable speed drive (VSD) system. For each PWM strategy, acoustic noise level, line-to-line voltage and current waveform, and current harmonic spectrum are measured with respect to the VSD of induction motor. The Suboptimal PWM strategy showed the similar harmonic effects to those of the Optimal PWM strategy. In addition, the microprocessor application was available to the former. The TP PWM strategy was excellent in that it could reduce the CPU load and increase the output voltage since the strategy could control only two phase of the three.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.6
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• pp.569-577
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• 2005

In this paper, a new control scheme to use 6-switch IGBI module for 3-phase switched reluctance motors(SRM) is proposed. Compared with the conventional asymmetric bridge converter topology, it can minimize the entire system size and cost. Therefore, it may have a new topology lot SRM to compare the other ac motors, such as induction motors, brushless dc motors, and so on. The validity of the proposed method is verified by simulation, and experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.561-569
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• 1999

In this paper, the diode bridge-type ZVT(Zero- Voltage Transition) inverter is proposed. It consists of one a auxiliaI${\gamma}$ switch, three resonant inductors and six blockin당 diodes. So, the main advantage of the proposed t torXJ!ogy is the reduction of the auxiliar${\gamma}$ switch compare to the conventional ZVT inverter. The topology of t the propostxl lVT inverter is analyztxl with a description of the control conditions based on the load current. A And the resonant period control for operating the proposed inverter optimally is discussed by using resonant i inductor current ftxxlback. To verify the proposed topology, the detailed simulation and exJX끼mental results i indicate that zero volta당e operation during transition can be achieved.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.5
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• pp.430-437
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• 2004

This thesis proposes novel SRP-PWM(Separately Random Pulse Position PWM) techniques and novel two-phase switching pattern applied to four-switch inverter, having various advantages such as operation time decrease that is required for decrease of switching damage, easy of implementation and inverter control at high frequency switching. In this thesis, we wish to confirm that SRP-PWM techniques disperse harmonic spectrum of inverter output current evenly into wide frequency area, that is, side-band of specification frequency. And we confirm the harmonic reduction effect of proposed techniques. Therefore, we will achieve an experiment by IGBT inverter using DSP and will verify the validity of proposed techniques compared with simulation results that use MATLAB/SIMULINK.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.749-752
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• 1993

This paper deals with the development of three phase 440[V], 500[KVA] Inverter system using the IGBT Devices. IGBT's have been used very successfully in variable frequency induction motor drive equipment. Problems associated with power devices characteristics when power devices are operated in parallel, such as balanced switching behavior and thermal stability, can be solved by using NPT type IGBT's. By Experimental results, it is confirmed that the voltage overshoot and reverse recovery current was very low. The equipment had proved to be reliable and short circuit proof. In addition, the performances in term of thermal characteristics, protection functions and stability are satisfactory.

• Journal of Advanced Navigation Technology
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• v.16 no.6
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• pp.1123-1133
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• 2012

This study configuration Vector Control System which is stable and has outstanding Dynamic Characteristics in Very Low Speed Region and Low Speed Region, and proposes Instantaneous Speed Observer and Very Low Speed Control method and vector control system of the speed estimation a using Reduced-Dimensional State Observer. The Observer proposed in this system, by appling Reduced-Dimensional State Observer to Load-Torque estimation and using for speed estimation, implements system composition simply and is capable of accurate Instantaneous Speed estimation in Very Low Speed Region. Also, this study reduces influence by System Noise and suggests an induction motor speed control system which is effective in Load Disturbance, modeling error, estimation noise and so on without changing pole of an Observer.

• Journal of Electrical Engineering and Technology
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• v.2 no.4
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• pp.468-477
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• 2007

The DTC of voltage source inverter-fed PMSMs is based on hysteresis controllers of torque and flux. It has several advantages, namely, elimination of the mandatory rotor position sensor, less computation time, and rapid torque response. In addition, the stator resistance is the only parameter, which should be known, and no reference frame transformation is required. The DTC theory has achieved great success in the control of induction motors. However, for the control of PMSM drives proposed a few years ago, there are many basic theoretical problems that must be clarified. This paper describes an investigation into the effect of the zero voltage space vectors in the DTC system and points out that if using it rationally, not only can the DTC of the PMSM drive be driven successfully, but torque and flux ripples are reduced and overall performance of the system is improved. The implementation of DTC in PMSM drives is described and the switching tables specific for an interior PMSM are derived. The conventional eight voltage-vector switching table, which is namely used in the DTC of induction motors does not seem to regulate the torque and stator flux in a PMSM well when the motor operates at low speed. Modelling and simulation studies have both revealed that a six voltage-vector switching table is more appropriate for PMSM drives at low speed. In addition, the sources of difficulties, namely, the error in the detection of the initial rotor position, the variation of stator resistance, and the offsets in measurements are analysed and discussed.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.26-34
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• 1999

According to increase of nonlinear power electronics equipment, active power filters have been researched and developed for many years to compensate harmonic disturbances and reactive power. However the commercial of active power filter is being proceeded slowly, because the cost of active power filter compared to the passive filter for harmonic and reactive power compensation is expensive. Especially, the use of DSP (Digital Signal Processing) chip, which is frequently used to control 3-phase active power filter, is a factor of increasing the cost of active power filters. On the other hand, the use of only analog controller makes the controller's circuits much more complicate and depreciates the flexibilities of controller. In this paper, a controller with low cost for 5[kVA] 3-phase active power filter system is designed. To reduce the expense of active filter system, the presented controller is composed of digital control part using Intel 80C196KC $\mu$P and analog control part using hysteresis controller for current control. Characteristic analysis of designed controller for active filter system is performed by computer simulation and compensating characteristics of the designed controller are verified by experiment.tegy can apply to the vector control, leading to better output torque capability in the ac motor drive system. This strategy is that in the overmodulation range, the d-axis output current is given a priority to regulate the flux well, instead the q-axis output curent is sacrificed. Therefore, the vector control even in the overmodulation PWM operation can be achieved well. For this purpose, the d-axis output voltage of a current controller to control the flux is conserved. the q-axis output voltage to control the torque is controlled to place the reference voltage vector on the hexagon boundary in case of the overmodulation. The validity of the proposed overall scheme is confirmed by simulation and experiments for a 22[kW] induction motor drive system.