• Journal of Power Electronics
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• v.16 no.1
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• pp.111-120
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• 2016

Generally, a single phase H-bridge converter feeding a single primary track is employed in conventional inductive power transfer systems. However, these systems may not be suitable for some high power applications due to the constraints of the semiconductor switches and the cost. To resolve this problem, a novel dual coupled primary tracks IPT system consisting of two high frequency resonant inverters feeding the tracks is presented in this paper. The primary tracks are wound around an E-shape ferrite core in parallel which enhances the magnetic flux around the tracks. The mutual inductance of the coupled tracks is utilized to achieve adjustable power sharing between the inverters by configuring the additional resonant capacitors. The total transfer power can be continuously regulated by altering the pulse width of the inverters' output voltage with the phase shift control approach. In addition, the system's efficiency and the control strategy are provided to analyze the characteristic of the proposed IPT system. An experimental setup with total power of 1.4kW is employed to verify the proposed system under power ratios of 1:1 and 1:2 with a transfer efficiency up to 88.7%. The results verify the performance of the proposed system.

• Journal of Power Electronics
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• v.17 no.2
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• pp.389-397
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• 2017

A control scheme for stand-alone inverters that utilizes an inductor current observer (ICO) is proposed. The proposed method measures disturbance load currents using a current sensor and it estimates the inductor current using the ICO. The filter parameter mismatch effect is analyzed to confirm the ICO's controllability. The ICO and controllers are designed in a continuous-time domain and transferred to a discrete-time domain with a digital delay. Experimental results demonstrate the effectiveness of the ICO using a 5-kVA single-phase stand-alone inverter prototype. The experimental results demonstrate that the observed current matches the actual current and that the proposed method can archive a less than 2.4% total harmonic distortion (THD) sinusoidal output waveform under nonlinear load conditions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1751-1758
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• 2003

This paper describes speed control of a permanent split capacitor single phase induction motor using SHE PWM inverters. The inverter is controlled by V55 microprocessor and its range is larger than other systems. Due to the V/F control with SHE(Selected Harmonic Elimination) PWM, continuously variable speed is attained and THD(Total Harmonic Distortion) is decreased. This is verified by simulations and experimental results.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.168-180
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• 2018

In order to achieve the high quality output voltage of single-phase voltage source inverters, in this paper an Adaptive Complementary Sliding Mode Control (ACSMC) is proposed. Firstly, the dynamics model of the single-phase inverter with lumped uncertainty including parameter variations and external disturbances is derived. Then, the conventional Sliding Mode Control (SMC) and Complementary Sliding Mode Control (CSMC) are introduced separately. However, when system parameters vary or external disturbance occurs, the controlling performance such as tracking error, response speed et al. always could not satisfy the requirements based on the SMC and CSMC methods. Consequently, an ACSMC is developed. The ACSMC is composed of a CSMC term, a compensating control term and a filter parameters estimator. The compensating control term is applied to compensate for the system uncertainties, the filter parameters estimator is used for on-line LC parameter estimation by the proposed adaptive law. The adaptive law is derived using the Lyapunov theorem to guarantee the closed-loop stability. In order to decrease the control system cost, an inductor current estimator is developed. Finally, the effectiveness of the proposed controller is validated through Matlab/Simulink and experiments on a prototype single-phase inverter test bed with a TMS320LF28335 DSP. The simulation and experimental results show that compared to the conventional SMC and CSMC, the proposed ACSMC control strategy achieves more excellent performance such as fast transient response, small steady-state error, and low total harmonic distortion no matter under load step change, nonlinear load with inductor parameter variation or external disturbance.

• Journal of Power Electronics
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• v.17 no.2
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• pp.533-541
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• 2017

This paper presents a novel Parameter-Independent Fictive-Axis (PIFA) approach for the Voltage-Oriented Control (VOC) algorithm used in grid-tied single-phase inverters. VOC is based on the transformation of the single-phase grid current into the synchronous reference frame. As a result, an orthogonal current signal is needed. Traditionally, this signal has been obtained from fixed time delays, digital filters or a Hilbert transformation. Nevertheless, these solutions present stability and transient drawbacks. Recently, the Fictive Axis Emulation (FAE) VOC has emerged as an alternative for the generation of the quadrature current signal. FAE requires detailed information of the grid current filter along with its transfer function for signal creation. When the transfer function is not accurate, the direct and quadrature current components present steady-state oscillations as the fictive two-phase system becomes unbalanced. Moreover, the digital implementation of the transfer function imposes an additional computing burden on the VOC. The PIFA VOC presented in this paper, takes advantage of the reference current to create the required orthogonal current, which effectively eliminates the need for the filter transfer function. Moreover, the fictive signal amplitude and phase do not change with a frequency drift, which results in an increased reliability. This yields a fast, linear and stable system that can be installed without fine tuning. To demonstrate the good performance of the PIFA VOC, simulation and experimental results are presented.

• Journal of Power Electronics
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• v.11 no.6
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• pp.811-818
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• 2011

Modulation strategies for multilevel inverters have typically focused on synthesizing a desired set of sinusoidal voltage waveforms using a fixed number of dc voltage sources. This makes the average power drawn from different dc voltage sources unequal and time varying. Therefore, the dc voltage sources are unregulated and require that corrective control action be incorporated. In this paper, first two new selections are proposed for determining the dc voltage sources values for asymmetric cascaded multilevel inverters. Then two modulation strategies are proposed for the dc power balancing of these types of multilevel inverters. Using the charge balance control methods, the power drawn from all of the dc sources are balanced except for the dc source used in the first H-bridge. The proposed control methods are validated by simulation and experimental results on a single-phase 21-level inverter.

• 전기의세계
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• v.30 no.1
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• pp.41-46
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• 1981

In the current source inverters (CSI), which are widely used recently in many applications, in order to reduce the harmonic contents in the output line current, twelve-step waveform is synthesized usually by a phase-shifted addition of the output currents of two single CSI's. In this paper a new method of synthesis of the 12-step current waveform is suggested which employes a main and a new auxiliary inverters having lower capacity, and thus is economically advantageous over the conventional scheme. DC-side commutation and energy rebond circuit as described in Part I are also employed in this proposed twelve-step CIS for effective commutation and high reliability. Experimental results are also given in oscillgrams.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.147-148
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• 2015

This paper presents an odd harmonic repetitive controller for single-phase UPS inverters. The proposed repetitive controller achieves the low output voltage THD and reduces the steady-state error by eliminating odd harmonic distortions caused by nonlinear and unbalanced loads. The proposed control scheme is verified through experiment using a 5kW single-phase T-type inverter.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.1
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• pp.47-53
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• 2006

In this paper, a simple scheme compensating for the effect of dc-link ripple voltages on output voltage of two-leg and three-phase PWM inverters is proposed, where single-phase half-bridge PWM convertor and two-leg inverter are used. The voltage at neutral point of the dc-link is controlled so that the upper-half of do-link voltage is equal to the lower-half voltage in average concept. However, the effect of the do-link ripple voltage results in the inverter output voltage and current distortion. This effect can be eliminated by introducing a compensation voltage in switching time calculation. Also, the inverter dead time should be compensated for sinusoidal output waveform. The proposed scheme has been verified by experimental results which were obtained from the V/F constant operation of the induction motor fed by two-leg inverter.

• Journal of Power Electronics
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• v.13 no.2
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• pp.322-328
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• 2013

This paper presents a modified Current Source Parallel Resonant Push-pull Inverter (CSPRPI) for single phase induction heating applications. One of the most important problems associated with current source parallel resonant inverters is achieving ZVS in transient intervals. This paper shows that a CSPRPI with the integral cycle control method has dynamic ZVS. According to this method, it is the Phase Locked Loop (PLL) circuit that tracks the switching frequency. The advantages of this technique are a higher efficiency, a smaller package size and a low EMI in comparison with similar topologies. Additionally, the proposed modification results in a low THD of the ac-line current. It has been measured as less than %2. To show the validity of the proposed method, a laboratory prototype is implemented with an operating frequency of 80 kHz and an output power of 400 W. The experimental results confirm the validity of the proposed single phase induction heating system.