• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.9 no.5
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• pp.51-56
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• 1995

The transistors of single phase 3 level PWM Inverter compose output power transistors and neutral point clamping transistors, which are NPN transistors. Waveforms of driving signals for this are PWM waves for power transistors and period operating waves for neutral point clamping transistors, which signals made W-type modulation from rectangular and sine wave. The output power transistors operate at ON-time complementary and neutral point clamping transistors operate at OFF-time complementary respectively. Therefore, each transistors operate in half period at parallel. Characteristics of this inverter circuit is parallel switching method about series switching method of general inverter. As modulation of 3 level drive signals made from full-wave rectifier of sine wave and rectangular wave, which are level wave about 3 level of complementary transistor inverter. So, this circuit composed complementary operation inverter of NPN transistors only compare with PNP-NPN complementary inverter, which have high power 3 level inverter of complementary operation.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.167-174
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• 2008

In this paper, the analysis on type effect of inverter output voltage distortion on the control of an induction motor is discussed. The inverter output voltage is distorted differently from the reference voltage owing to the inverter nonlinear characteristic. The inverter nonlinear characteristic results from the voltage drop, the inherent characteristic of the power semiconductor, and the dead time for preventing the short circuit of the inverter leg. This characteristic distorts the inverter output voltage and then, causes the motor flux estimation error. Although this characteristics do not significantly effect in the general-purpose induction motor control, but significantly effect on the low-speed operation of high performance motor control such as the sensorless vector control.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.534-537
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• 1997

Solar power systems have become popular in the modem electric energy system. In order to supply the DC power, generated by solar cells, to the electric power system, the solar power system requires DC-to-AC power conversion. A line-commutated inverter or a forced-commutated inverter can be used in the DC-to-AC power conversion. Because of the nonlinear V-I characteristics of the solar cells, multiple operating points determined by the control mode of the inverter exist in the DC V-I state plane of the solar power system. In this paper, the stability of utility-interactive solar power system with a line-commutated inverter is analyzed at various operating points, using the eigenvalue method and the state-plane analysis technique. The stability of a forced-commutated inverter case is also anaiyzed and compared to that of the line-commutated inverter case.

• Journal of Power Electronics
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• v.16 no.2
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• pp.532-541
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• 2016

A single-phase asymmetrical cascaded multilevel inverter is introduced with the goal of increasing power quality with the reduction of power in insulated-gate bipolar transistor (IGBT) switches. In the present work, the proposed inverter topology is analyzed and generalized with respect to different proposed algorithms for choosing different voltage source values. To prove the advantages of the proposed inverter, a case study involving a 17-level inverter is conducted. The simulation and experimental results with reduced THD are also presented and compared with the MATLAB/SIMULINK simulation results. Finally, the proposed topology is compared with different multilevel inverter topologies available in the literature in terms of the number of IGBT switches required with respect to the number of levels generated in the output of inverter topologies.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.1-6
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• 2014

In-wheel driving inverter inside engine room sometimes operates in the harsh environment like high temperature of about $105^{\circ}C$. Especially, the size and power density of the inverter has become smaller and more increased. Thus, it is essential to manage the temperature of the inverter with IGBT (Insulated Gate Bipolar Transistor) switching devices for performance and endurance, because the temperature can be getting increase. In this paper, we performed the thermal flow analysis of inverter models with wave type and pin fin type cooling channels, and investigated the heat transfer characteristics of the inverter models using cooling water on channels at 8 L/min and $65^{\circ}C$. Also, we compared the thermal performance under various conditions such as coolant flow rate and layered power module structure. Therefore, we determined the feasibility of the initial inverter models and the thermal performance enhancement.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.804-810
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• 2016

Photovoltaic system construction of the module capacity in domestic is specified criteria to less than 105% of the inverter capacity. However, the modules are installed in the outdoor actual output is reduced due to factors such as the irradiation intensity, module surface temperature. Thus, it needs the capacity of the inverter to be designed according to the actual module output. In this paper, the first approach to find the actual module output is to analyze the actual PV system monitoring data. Next, four sites where the loss analysis, system utilization, inverter utilization, and the ratio of the inverter overload are performed using PVSYST software. By changing the ratio of the module capacity, the inverter capacity of the site B is confirmed 20% less than the module capacity. Site A, C, D are identified as the ratio of the inverter capacity is 10% less than the module capacity.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.1
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• pp.24-31
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• 1992

A 24 pulse current source inverter for reducing the harmonics in output currents is presented in this paper. The proposed system operates a 24 pulse inverter by adding only tap changing circuit which consists of several taps and static switching elements to the 12 pulse inverter, which is the double connected 3 phase 6 pulse inverter with an auto transfomer. Also to optimize the effectiveness of the harmonic reduction, the optimum turn ratio and tap changing control angle of auto transfomer are decided by digital simulation and its validity is verified with experiment. And under the optimum condition, it is clarified that the harmonics components involved in the output current of the proposed inverter are nearly equal to those of the conventional 24 pulse inverter.

• Journal of the Semiconductor & Display Technology
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• v.13 no.4
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• pp.43-48
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• 2014

Two-level inverter has some disadvantages like high harmonics contained in the output current, efficiency limit and stress to switching device as IGBT and FET. Many researches have reported multi-level inverter to complement two-level inverter of problems. In this paper, we suggest MPPT algorithm of multi-string three-level solar inverter that considered nowadays. We added midpoint controller in order to implement the MPPT algorithm because the three-level inverter has to need midpoint controller and procured the stability of direct current link. We verify the superiority of multi-string T-Type inverter and the algorithm we suggested with solar irradiance variation experiment and MPPT efficiency measurement. The MPPT efficiency was confirmed with a high efficiency more than 99.97%.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.313-314
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• 2012

In this paper presents study of T-Type multi level inverter for utility interactive photo voltaic inverter. In order to increase efficiency and performance of utility interactive photo voltaic (UIPV) system, we propose multi level PCS topology, such as T-type inverter. The control algorithm for utility interactive inverter is implemented by simulation and experimentation, which includes dc-bus and midpoint voltage controller, ac-grid current controller and PLL algorithm.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.187-189
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• 2007

In this paper, the cascade 3-phase IHMCL inverter using two low frequency transformers is proposed. The proposed inverter is constructed by connecting a 3-phase IHCML inverter. the cascade 3-phase IHCML inverter has several advantages. One advantage is that only one input power source is required because of using transformers to isolate. Another advantage is that the switching frequency of the high power switches is almost fundamental frequency of reference and the other the switching frequency of the low power switches is higher. It can be known that cascade 3 phase IHCML inverter has the excellent efficiency and the outstanding electric quality. lastly, we tested the 5kW cascade 3-phase IHCML inverter to clarify the proposed electric circuit and reasonableness of control signal for the proposed inverter.