• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.631-634
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• 1999

A new multiple-output dc-to-dc converter based on a switched capacitor circuit is proposed. The proposed converter offers multiple outputs that can be individually regulated by a direct output voltage feedback or indirect cross regulations. The performance of the new converter is demonstrated using a 10W experimental converter that delivers 5V/1A output and 3.3V/1A output from a 10∼15V input source.

• Journal of Power Electronics
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• v.19 no.6
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• pp.1536-1543
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• 2019

This paper presents an improved torque predictive control (TPC) for permanent magnet synchronous motors (PMSMs) using an indirect matrix converter (IMC). The IMC has characteristics such as a high power density and sinusoidal waveforms of the input-output currents. Additionally, this configuration does not have any DC-link capacitors. Due to these advantages of the IMC, it is used in various application field such as electric vehicles and railway cars. Recently, research on various torque control methods for PMSM drives using an IMC is being actively pursued. In this paper, an improved TPC method for PMSM drives using an IMC is proposed. In the improved TPC method, the magnitudes of the voltage vectors applied to control the torque and flux of the PMSM are adjusted depending on the PMSM torque control such as the steady state and transient response. Therefore, it is able to reduce the ripples of the output current and torque in the low-speed and high-speed load ranges. Additionally, the improved TPC can improve the dynamic torque response when compared with the conventional TPC. The effectiveness of the improved TPC method is verified by experimental results.

• Journal of Power Electronics
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• v.15 no.3
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• pp.702-711
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• 2015

In this paper, an effective carrier-based modulation (CBM) strategy to reduce the switching losses for indirect matrix converters (IMCs) is presented. The discontinuous pulse width modulation method is applied to decrease the switching numbers in one carrier cycle, and an optimum offset voltage is selected to avoid commutations of the high output phase currents. By decreasing the switching numbers along with avoiding commutation of the high currents, the proposed CBM strategy significantly reduces the switching losses in IMCs. In addition, the proposed CBM strategy is independent of load conditions, such as load power and power factor, and it has good performance in terms of the input/output waveforms. Simulation and experimental results are provided to verify the effectiveness of the proposed CBM strategy.

• Journal of Power Electronics
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• v.19 no.5
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• pp.1142-1152
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• 2019

This paper presents a control method for reducing the current distortion in an indirect matrix converter (IMC) operating in boost mode under unbalanced input conditions. IMCs operating in boost mode are useful in distributed generation (DG) systems. They are connected with renewable energy systems (RESs) and the grid to transmit the power generated by the RES. However, under unbalanced voltage conditions of the RES, which is connected with the input stage of the IMC operating in boost mode, the input-output currents are distorted. In particular, the output current distortions cause a ripple of the power, which is transferred to the grid. This aggravates the reliability and stability of the DG system. Therefore, in this paper, a control method using positive/negative sequence voltages and currents is proposed for reducing the current distortion of both side in IMCs operating in boost mode. Simulation and experimental results have been presented to validate effectiveness of the proposed control method.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.4
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• pp.466-472
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• 2013

The paper presents a novel DC grid connection topology and control strategy for doubly-fed induction generator (DFIG) based wind power generation system. In order to achieve the wind power conversion, the stator side converter and the rotor side converter is used to implement the DFIG control based on the indirect air-gap flux orientation, and a DC/DC converter is used for the DFIG system to DC grid connection. The maximum power point tracking and DC voltage droop control can also be implemented for the proposed DFIG system. Finally, a 4-terminal DFIG-based multi-terminal DC grid system is developed by Matlab to validate the availability of the proposed system and control strategy.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.10
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• pp.15-27
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• 1997

Quasti-static cutting force variations in milling process are measured indirectly using spindle motor current. Quasi-static sensitivity of the spindle motor current is higher than that of the feed motor current. Magnitude of the spindle motor current is independent of cutting direction. The linear relationship between the cutting force and the spimdle motor RMS current at various spindle rotational speed is obtained. Frequency/ Voltage(F/V) converter voltage is measured to identify the spindle speed and to determine the cutting force at various spindle speeds. Overload on the tool during milling process can be detected using the proposed indirect cutting force measurement. Based on these measurements, cutting force is regulated at a constant level by feedrate control.

• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.255-262
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• 1998

The neural network can roughly be classified as the specialized control, indirect control and general schemes. Neural network is adopted for MPPT of solar array. And back propagation algorithm also is used to train neural network controller. We investigate the possibilities of $P_{max}$ control using the neural networks, and then we also examine about operating the solar cell at an optimal voltage comprise of temperature compensated voltage with boost converter. Proposed boost converter of MPPT system is studied by simulation and is implemented by using a microprocessor(80c196kc) which controls duty ratio of the boost converter.

• Journal of Power Electronics
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• v.14 no.3
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• pp.458-467
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• 2014

In this paper, a single-phase current-source bidirectional converter topology for V2G applications is proposed. The proposed converter consists of a single-phase current-source rectifier (SCSR) and an auxiliary switching network (ASN). It offers bidirectional power flow between the battery and the grid in the buck or boost mode and expands the output voltage range, so that it can be compatible with different voltage levels. The topology structure and operating principles of the proposed converter are analyzed in detail. An indirect control algorithm is used to realize the charging and discharging of the battery. Finally, the semiconductor losses and system efficiency are analyzed. Simulation and experimental results demonstrate the validity and effectiveness of the proposed topology.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.5
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• pp.420-423
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• 2020

This study proposes an indirect constant voltage control algorithm for hybrid solid-state transformers (HSSTs) by using primary side information. Considering the structure of HSSTs, measuring voltage and current information on the primary side of a transformer is necessary to control the converter and inverter of the power converter. The secondary side output voltage is measured to apply the conventional secondary side constant voltage control algorithm, and thus, the digital control board requires the same rated insulation voltage as that of the transformer. To solve this problem, the secondary voltage of the transformer obtained from the tap voltage is used. Moreover, output voltage decreases as load increases because the proposed indirect constant voltage control scheme does not consider the cable impedance between the secondary output terminal and the load. This study also proposes a technique for compensating the secondary output voltage by using the primary current of the transformer and the resistance value of the cable. An experiment is conducted using a scale-down HSST prototype consisting of a 660 V/220 V tap transformer. The problem of the proposed indirect constant voltage control strategy and the improvement effect due to the application of the compensation method are compared using the derived experimental results.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.370-372
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• 1996

A control scheme for the Voltage-sourced PWM converter based on space vector equations is introduced. The main advantages of this new control scheme are that sinusoidal line currents with nearly unity power factor, ripple-free DC voltage output are achevied without current sensors. The dynamical equations with battery model is derived. The proposed scheme is verified by computer simulation.