• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.8
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• pp.331-337
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• 1985

An inverter-excited induction generator is discussed in this paper. A brief review of the capacitor-excited induction generator is given and the steady state characteristics of the induction generator excited by an inverter are evaluated. It is shown that the output voltage of the system can be controlled by adjusting the slip, for given operating conditions. The introduction of feedback control makes it possible to control the output voltage stably over the wide range of speed and load. Experimental results are given. The output of the induction generator is then converted into a CVCF(Constant Voltage-Constant Frequency) power source using a PWM inverter with simple control circuit.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.2
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• pp.86-93
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• 2018

In this work, control methods and operating modes are proposed to manage standalone microgrid. A standalone microgrid generally consists of two sources, namely, battery energy storage system (BESS) and diesel generator (DG). BESS is the main source that supplies active and reactive power regardless of load conditions, whereas DG functions as an auxiliary power source. BESS operates in a constant voltage constant frequency (CVCF) control, which includes proportional-integral + resonant controller in a parallel structure. In CVCF control, the concept of fundamental positive and negative transformation is utilized to generate a three-phase sinusoidal voltage under imbalanced load condition. Operation modes of a standalone microgrid are divided into three modes, namely, normal, charge, and manual modes. To verify the standalone microgrid along with the proposed control methods, a demonstration site is constructed, which contains 115 kWh lead-acid battery bank, 50 kVA three-phase DC - AC inverter, and 50 kVA DG and controllable loads. In the CVCF control, the total harmonic distortion of output voltage is improved to 1.1% under imbalanced load. This work verifies that the standalone microgrid provides high-quality voltage, and three operation modes are performed from the experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.4
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• pp.567-575
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• 2016

This paper proposed the voltage control of stand-alone inverter for power quality improvement under unbalanced and non-linear load. The 3-phase DC-AC inverter controls CVCF(Constant Voltage Constant Frequency) and selective harmonic eliminate method in stand-alone mode by PR controller, and the stand-lone inverter supplies stable sinusoidal voltage to balanced, unbalanced and non-linear loads. The total harmonic distortion(THD) of line-to-line load voltage($V_{LL}$) is 1.2% in the balanced load. THD of $V_{LL}$ is reduced from 5.2% to 1.4% and 6.7% to 3.5%, respectively unbalanced and non-linear load. The stand-alone inverter can be supplies sinusoidal balanced voltage to unbalanced load because the voltage unbalanced factor(VUF) of $V_{LL}$ is reduced from 5.2% to 1.4% in the unbalanced load. Feasibility of control method for a stand-alone inverter will be verified through 30kW stand-alone inverter system.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.348-351
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• 2001

In this paper, voltage-fed high frequency resonant inverter of instantaneous current phaser control method used to DC voltage source separated is proposed. In the output control method, a novel circuit type of phase shift driving signal method with CVCF illustrated, also the operation principle of the proposed circuit is described in detail and its characteristics are presented as to normalized parameters. According to the each mode, in order to the circuit analysis and characteristic evaluation of the state equation are derives and present used to normalized parameter. In the future, this proposed inverter show that it can be practically used as power source system for the lighting equipment of discharge lamp, DC-DC converter etc.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.548-551
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• 2000

The battery charger for high speed trail car is very important power source for the purpose of safty and system stability. it provides control power of VVVF, CVCF, DC/DC converter and inverter for traction motor. This paper included power circuit of the ZVZCS type battery charger for high speed trail car and battery included power circuit of the ZVZCS type battery charger for high speed trail car and inverter for traction motor. This paper included power circuit of the ZVZCS type battery charger for high speed trail car an battery charging algorithm. Also the optimum parallel operation of 50Kw battery charger for high speed trail car and charging control method of Ni-Cd battery illustrates validity and effectiveness through the experiments.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.185-189
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• 2001

This paper presents a precision voltage control technique of a single phase PWM inverter for a constant voltage and constant frequency(CVCF) applications. The proposed control employes a PLL compensating loop which minimize the steady state error and phase delay. The computer simulation and experiment are carried out for the actual single phase PWM inverter and the results well demonstrate the effectiveness of the proposed control.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1224-1226
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• 2000

In this paper, load paralleled type FB series resonant inverter of a new novel type is proposed. In the output control method, phase-shift driving signal control method with CVCF introduces. Also by driving signal patterns, the operation principle of the proposed circuit in detail is described and its characteristics are compared on separated ratio(n). According to each the mode in order to the analysis and characteristic evaluation of the circuit state equations are derived and presented using normalized parameter. To verify the theoretical analysis result, experimental results are provided.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1720-1728
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• 2018

This paper proposes a novel soft starting algorithm by using PWM inverter technique to control an amplitude of the motor starting current at a single-phase induction motor (SPIM). Traditional SPIM starting methods such as a Split-Phase, Capacitor-Start, Permanent-Split Capacitor (PSC), Capacitor-Start Capacitor-Run (CSCR), basically cannot control the magnitude of starting current due to the fixed system structures. Therefore, in this paper, a soft starting algorithm based on a proportional resonant (PR) control with a variable and constant frequency is proposed to reduce the inrush current and starting up time. In addition, a transition algorithm for operation modes is devised to generate a constant voltage and constant frequency (CVCF). The validity and effectiveness of the proposed soft starting method and transition algorithm are verified through experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.2
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• pp.131-138
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• 2007

In this paper, a novel nonlinear control method of the CVCF(constant voltage and constant frequency) output voltage for the three-phase PWM inverter with LC output filters is proposed. A nonlinear modeling including the output LC filters is linearized by feedback linearization theory, the controllers of which can be designed based on a linear control theory. It is applied to the DC/AC power conversion of the PWM inverter for stand-alone wind power generation system. It has been verified by the experimental results that the proposed control scheme gives high dynamic responses at load variation as well as a zero steady-state error.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1088-1091
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• 1992

Programmed PWM(Pulse Width Modulated) generation techniques eliminating several low order harmonics have been widely used in the inverter circuit which produces minimum current ripple, reduced torque pulsation and thereby improves overall system performance. However, the applications of the programmed PWM technique are limited to CVCF(Constant Voltage Constant Frequency) applications and various motor drives. Although the programmed PWM produces a lower harmonic distorted waveform than the carrier modulated PWM, real-time programming is not possible because of the complicated calculation required for the gating signal. In this paper, a new programmed PWM technique named TAM (time averaging model) is developed to compensate for the demerits of the conventional programmed PWM technique with moderate harmonic distortion. Computer simulations are performed to verify the performance of the proposed algorithm.