• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.4
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• pp.543-552
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• 1996

The goal of this paper is to developed a DSP based power analyzing and control system by 3-Dimensional (3-D) space current co-ordinates. A developed system is made up of 486-PC and DSP (Digital Signal Processor) board, Active Power Filter, Non-linear thyristor load, and Power analyzing and control program for Windows. Power is analyzed using signal processing techniques based on the correlation between voltage and current waveforms. Since power analysis algorithm is performed by DSP, power analysis is achieved in real-time even under highly dynamic nonlinear loading conditions. Combining control algorithm with power analysis algorithm is performed by DSP, power analysis is achieved in real-time even under highly dynamic nonlinear loading conditions. Combining control algorithm with power analysis algorithm, flexibility of the proposed system which has both power analysis mode and control mode, is greatly enhanced. Non-active power generated while speed of induction motor is controlled by modulating firing angle of thyristor converter, is compensated by Active Power Filter for verifying a developed system. Power analysis results, before/after compensation, are numerically obtained and evaluated. From these results, various graphic screens for time/frequency/3-D current co-ordinate system are displayed on PC. By real-time analysis of power using a developed system, power quality is evaluated, and compared with that of conventional current co-ordinate system. (author). refs., figs. tabs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.12
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• pp.1983-1993
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• 1993

A power-reduction technique for full-flash A/D converters is proposed. As the resolution of a full-flash A/D converter increases linearly, the number of comparators increases exponentially. The power dissipation is generally larger than other A/D converter architectures because there are many comparators, and they are operating continuously. In this proposed architecture, only a selected number of conmarators are made to operate instead of activating all the comparators of the full-flash A/D convertor. To determine whichcomparators should be activated, voltage levelfider circuits are used. A new clock driver is developed to suppress the dynamic glitch noise which is fed back into the input stage of the comparator. By using this clock driver, the glitch noise in the current source is reduced to one fourth of that when the typical clock signal is applied. The proposed architecture has been implemented with 1.2 m 5GHz BiCMOS technology. The maximum conversion speed is 350Msamples/s. and dissipates only 900mW.

• Journal of Power Electronics
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• v.17 no.2
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• pp.490-500
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• 2017

Fuel cell (FC) is a promising power supply in electric vehicles (EV); however, it has poor dynamic performance and short service life. To address these shortcomings, a super capacitor (SC) is adopted as an auxiliary power supply. In this study, the frequency decoupling control method is used in electric vehicle energy system. High-frequency and low-frequency demand power is provided by SC and FC, respectively, which makes full use of two power supplies. Simultaneously, the energy system still has rapidity and reliability. The distributed power system (DPS) of EV requires DC-DC converters to achieve the desired voltage. The stability of cascaded converters must be assessed. Impedance-based methods are effective in the stability analysis of DPS. In this study, closed-loop impedances of interleaved half-bridge DC-DC converter and phase-shifted full-bridge DC-DC converter based on the frequency decoupling control method are derived. The closed-loop impedance of an inverter for permanent magnet synchronous motor based on space vector modulation control method is also derived. An improved Middlebrook criterion is used to assess and adjust the stability of the energy system. A theoretical analysis and simulation test are provided to demonstrate the feasibility of the energy management system and the control method.

• Journal of Power Electronics
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• v.17 no.4
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• pp.1048-1057
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• 2017

An indirect matrix converter (IMC) is a modern power generation system that enables a direct ac/ac conversion without the need for any bulky and limited lifetime electrolytic capacitor. This system also allows four-quadrant operation, generation of sinusoidal output voltage waveforms with variable frequency and amplitude, and control of input power factor. This study proposes a pulse-width modulation-based sliding-mode controller to achieve unity input-power factor operation of the IMC independently of the active power exchanged with the grid, as well as a fast dynamic response. The designed equivalent control law determines, at each sampling period, the appropriate q-axis component of the modulated input current to be injected into the grid through the LC input filter. An integral term of the error is included in the expression of the sliding surface to increase the accuracy of the control method. A double space vector modulation method is used to synthesize the direction of the space vector of the input currents as required by the sliding-mode controller and the space vectors of the target output voltages. Simulation and experimental results are provided to show the effectiveness and evaluate the performance of the proposed control method.

• Journal of Advanced Navigation Technology
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• v.26 no.1
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• pp.35-45
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• 2022

In this paper, we modeled the devices used easily in PV system circuits. In addition, for full operation of the photovoltaic system, a complete operation system for the DC-DC buck-boost converter and the MPPT control system was modeled and simulated to confirm good operation. we were constructed an actual system with the same conditions in the simulation and experimented. The purpose is to confirm the stable power supply through the load leveling by presenting the PCS considering ESS of photovoltaic power generation. we will do study to apply hybrid capacitors that have high energy density to the same size compared to the EDLC to DVR. As a result, we proposed a single-phase 3 kW grid-connected solar power converter.

• Journal of Power Electronics
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• v.16 no.1
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• pp.362-373
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• 2016

The on-line measurement of high-power IGBT collector current is important for the hierarchical control and short-circuit and overcurrent protection of its driver and the sensorless control of the converter. The conventional on-line measurement methods for IGBT collector current are not suitable for engineering measurement due to their large-size, high-cost, low-efficiency sensors, current transformers or dividers, etc. Based on the gate driver, this paper has proposed a current measuring circuit for IGBT collector current. The circuit is used to conduct non-intervention on-line measurement of IGBT collector current by detecting the voltage drop of the IGBT power emitter and the auxiliary emitter terminals. A theoretical analysis verifies the feasibility of this circuit. The circuit adopts an operational amplifier for impedance isolation to prevent the measuring circuit from affecting the dynamic performance of the IGBT. Due to using the scheme for integration first and amplification afterwards, the difficult problem of achieving high accuracy in the transient-state and on-state measurement of the voltage between the terminals of IGBT power emitter and the auxiliary emitter (u_Ee) has been solved. This is impossible for a conventional detector. On this basis, the adoption of a two-stage operational amplifier can better meet the requirements of high bandwidth measurement under the conditions of a small signal with a large gain. Finally, various experiments have been carried out under the conditions of several typical loads (resistance-inductance load, resistance load and inductance load), different IGBT junction temperatures, soft short-circuits and hard short-circuits for the on-line measurement of IGBT collector current. This is aided by the capacitor voltage which is the integration result of the voltage uEe. The results show that the proposed method of measuring IGBT collector current is feasible and effective.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.1
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• pp.1-8
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• 2019

In this study, a maximum power point tracking (MPPT) algorithm based on the perturb and observe (P&O) method with variable step size is proposed to improve the dynamic response characteristic of MPPT, using the existing P&O method. The proposed algorithm, which we verified by simulation and experiment, can track the maximum power point (MPP) through duty control and consisted of three operation modes, namely, constant voltage mode, fast mode, and variable step mode. When the insolation is constant, the voltage variation of the operating point at the MPP is reduced through the step size reduction of the duty in the variable step mode. Consequently, the vibration of the operating point is reduced, and the power generation efficiency is increased. When the insolation changes, the duty and the photovoltaic (PV) voltage are kept constant through the constant voltage mode. The operating point then rapidly tracks the new MPP through the fast-mode operation at the end of the insolation change. When the MPP is reached, the operation is changed to the variable step mode to reduce the duty step size and track the MPP. The validity of the proposed algorithm is verified by simulation and experiment of a PV system composed of a PV panel and a boost converter.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1110-1121
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• 2016

The mathematical model of a three phase PWM converter under the stationary αβ reference frame is deduced and constructed based on a Proportional-Resonant (PR) regulator, which can replace trigonometric function calculation, Park transformation, real-time detection of a Phase Locked Loop and feed-forward decoupling with the proposed accurate calculation of the inductance voltage vector. To avoid the parallel resonance of the LCL topology, the active damping method of the proportional capacitor-current feedback is employed. As to current vector error elimination, an optimized PR controller of the inner current loop is proposed with the zero-pole matching (ZPM) and cancellation method to configure the regulator. The impacts on system's characteristics and stability margin caused by the PR controller and control parameter variations in the inner-current loop are analyzed, and the correlations among active damping feedback coefficient, sampling and transport delay, and system robustness have been established. An equivalent model of the inner current loop is studied via the pole-zero locus along with the pole placement method and frequency response characteristics. Then, the parameter values of the control system are chosen according to their decisive roles and performance indicators. Finally, simulation and experimental results obtained while adopting the proposed method illustrated its feasibility and effectiveness, and the inner current loop achieved zero static error tracking with a good dynamic response and steady-state performance.

• Journal of Sensor Science and Technology
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• v.6 no.2
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• pp.137-144
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• 1997

In this paper, the design of a 10-bit 40-MS/s pipelined A/D converter is implemented to achieve low static power dissipation of 70 mW at the ${\pm}2.5\;V$ or +5 V power supply environment for high speed applications. A 1.5 b/stage pipeline architecture in the proposed ADC is used to allow large correction range for comparator offset and perform the fast interstage signal processing. According to necessity of high-performance op amps for design of the ADC, the new op amp with gain boosting based on a typical folded-cascode architecture is designed by using SAPICE that is an automatic design tool of op amps based on circuit simulation. A dynamic comparator with a capacitive reference voltage divider that consumes nearly no static power for this low power ADC was adopted. The ADC implemented using a $1.0{\mu}m$ n-well CMOS technology exhibits a DNL of ${\pm}0.6$ LSB, INL of +1/-0.75 LSB and SNDR of 56.3 dB for 9.97 MHz input while sampling at 40 MHz.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.239-241
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• 2008

A powered system with fuel cell is regarded as a high current and low voltage source. Effects of the loads on the electrical power source are important to optimize the integrated power system. The design parameters of the system should be chosen by taking into account the characteristics of the fuel cell, so the costs of the power system at given operating conditions can be reduced. Furthermore, the dynamics characteristic of the system is crucial to acquire performance in applications, particularly interactions between loads and the fuel cell system. Currently, no integrated simulation has been approached to analyze interrelated effects. Therefore, the dynamic models of power conversion system with a PEM fuel cell that includes the PEM fuel cell stack, DC/DC converter and associated controls is developed. Electric lads for the system are derived by using a power theory that separates a load current into active, reactive, distortion or a mixed current component. Dependency of the DC capacitor on the loads are analyzed.