• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.4
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• pp.193-199
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• 2011

The next generation domestic high speed railway system is a power distributed type and uses vector control method for motor speed control. Nowadays, inverter driven induction motor system is widely used. However, recently PMSM drives are deeply considered as a alternative candidate instead of an induction motor driven system due to their advantages in efficiency, noise reduction and maintenance. The next-generation high-speed train is composed of 2 converter units, 4 inverter units, and 4 Traction Motor units. Each motor is connected to the inverter directly. In this paper, the effects of IPMSM parameter variation to the system operation characteristics of the multi inverter driven high speed train system are investigated. The parallel connected inverter input-output characteristics are analyzed to the parameter mismatches of the IPMSM in 1C1M control using Matlab/Simulink, then the reliability of the simulation results are verified through experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.1
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• pp.38-44
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• 2015

This paper presents the sensorless drive method for mono inverter dual parallel (MIDP) surface mounted permanent magnet synchronous motor (SPMSM) drive system. MIDP motor drive system is a technique that can reduce the cost of the multi motor driving system. To maximize this merit of the MIDP motor drive system, the sensorless technique is essential to eliminate the position sensors. This paper adopts an appropriate sensorless method for MIDP SPMSM drive system, which uses the reduced order observer and phase locked loop (PLL) to reduce the calculation burden. The I-F control method is implemented for start-up and low speed operation. The validity and performance of the proposed algorithm are shown via experiments with 600-W SPMSMs.

• Journal of Power Electronics
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• v.10 no.6
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• pp.686-693
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• 2010

In this paper, a fault diagnosis method based on fuzzy logic for the three-parallel power converter in a wind turbine system is presented. The method can not only detect both open and short faults but can also identify faulty switching devices without additional voltage sensors or an analysis modeling of the system. The location of a faulty switch can be indicated by six-patterns of a stator current vector and the fault switching device detection is achieved by analyzing the current vector. A fault tolerant algorithm is also presented to maintain proper performance under faulty conditions. The reliability of the proposed fault detection technique has been proven by simulations and experiments with a 10kW simulator.

• The KSFM Journal of Fluid Machinery
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• v.18 no.2
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• pp.67-72
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• 2015

The purpose of this study is to achieve energy saving effect of inverter driving multistage centrifugal pump. For determining the operation points in the pump system, the system curves should be obtained experimentally. To get the system curves, three pumps combined in parallel and one pump operated with different rotational speeds. But for variable speed pump system, energy saving rates can not be evaluated from operation efficiencies. That is why operation efficiencies, system curves, duty cycles, and input powers of the pump system were measured by the constructed experimental apparatus. The duty cycle segmented into different flow rates and weighting the average value for each segment by the interval time. The system was operated with two different periods. The mean duty cycles were collected from apartment and found that the system operated at 40% and at 50% or below capacity. Measured energy saving rate was 58.16%. Estimating method of energy saving rate could be more effective operation index than that of operation efficiency.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.3
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• pp.244-251
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• 2010

High speed motors have been widely used in industries to reduce system size and improve power conversion efficiency. However, the high speed motors sometimes suffer from core losses caused by PWM current ripple; noting that the phase inductance, $L_s$, of high speed motor is smaller than that of ordinary motors. In the proposed topology, three PWM inverters are connected in parallel through nine coupled inductors. Compared to the PWM current ripple of the conventional single inverter system, that of the proposed scheme can be conspicuously reduced without the voltage drop at the inductors. In this paper a theoretical analysis of the output voltage of the proposed topology is presented, and then the validity of the proposed method is verified by experimental results.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1908-1916
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• 2018

This paper proposes a controller design method for suppressing the resonance generated in the slave motor in the middle and low speed operation range, according to the load and parameter differences between two motors, during parallel operation using the master and slave method that controls two surface permanent magnet synchronous motors connected in parallel by a single inverter. The proposed resonance suppression controller is directly obtained by analyzing the resonance characteristics, using the lead controller method. Therefore, it is possible to fundamentally reduce trial and error to set the controller gain. In addition, because the proposed resonance suppression controller was designed as a lead controller, the stability region of the system increased owing to the added zero point, making the system robust with respect to parametric variations. Simulations and experiments confirmed the usefulness of the proposed method and the system's robustness with respect to parametric variations.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.351-352
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• 2016

Since anti-islanding scheme of grid-connected inverter is a key function of standards compliance, unintentional islanding results in safety hazards, reliability, and many other issues. Therefore, many anti-islanding schemes have been researched, however, existing anti-islanding schemes show poor power quality and non-detection zone issues. Besides, most of them have problems which deteriorate performance of islanding detection under parallel-operation. Therefore, this paper proposes a new anti-islanding scheme that has both negligible power quality degradation, no non-detection zone and precise islanding detection under parallel-operation. Finally, both simulation and experimental results validate the proposed scheme.

• Journal of Industrial Technology
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• v.18
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• pp.149-155
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• 1998

This paper describes a reference flux angle selection for a vector control in the parallel operation system that consists of a inverter and several induction motors. In particular, this paper suggests which flux angle of motors prefers for the vector control in the train drive system that diameters of wheels are different. Through simulation for a 210[kW] induction motor drive system, it is clear that the vector control by using of the flux angle of a motor having a minimum wheel diameter leads to a minimum torque difference. However, it requires too many current sensors. So, it is shown that the vector control by a average flux angle of motors is preferable.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1222-1223
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• 2007

This paper suggests a 6-pulse-shift converter with PWM current-source inverter based on buck-boost configuration to improve the efficiency and to reduce the switching frequency of inverter for photovoltaic generation system, the device can be operated as interface system between solar module system and power system grid without energy storage cell. the circuit has six current-source buck-boost converter which operate chopper part has one full bridge inverter which make a decision the polarity of AC output. Therefore, the proposed PWM power inverter has advantages such as the reduction of witching loss and realization of unity power factor operation. the theoretical backgrounds are discussed and the input-output characteristics for the implemented prototype inverter using TMS320F2812 are verified experimentally in this paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.10
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• pp.1481-1487
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• 2017

This paper proposes a sensorless speed control algorithm for parallel-connected dual Surface-mounted Permanent Magnet Synchronous Motors fed by a single inverter. For stable parallel operation of synchronous motors with a single inverter, each motor has to be constantly kept in the synchronization state regardless of load torque. If the master motor with the larger load is controlled, the synchronous state will be maintained. Therefore, detection of the master motor is essential. Conventionally, the master motor is determined by comparing the rotor position error from the relation between the back-EMF for torque angle and the flux position. consequently, the position sensor is deemed essential for finding the rotor position. In this paper, we proposed a method that decides the magnitude of the load from the power angle of two motors due to the load variation and selects the motor to control through the sign function for the sensorless speed control without the position sensor. The results of simulation and experiment conducted verify the efficacy of the proposed method.