• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.6
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• pp.682-690
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• 2012

In this paper, a highly linear self oscillating mixers(SOM) using second harmonic injections are presented. The H-slot defected ground structure(DGS) is designed as a balanced resonator for oscillation in the proposed SOM. Since the H-slot DGS resonator achieves a high Q factor, it is a suitable structure to provide low phase noise for the oscillator. The single balanced mixer is utilized in this work and it provides good LO-RF isolation since balanced LO signals are suppressed at the RF input port. In order to inject the second harmonic of the IF, we propose two different methods using feedback loops. In the first method, IF achieves a 3.08 dB conversion gain at 226 MHz with input power of -20 dBm at 5 GHz RF input signal. The IF achieves 2 dB conversion gain at 423 MHz with the input power of -20 dBm at 5.2 GHz RF input signal in the second method. The measured IMD3s are 61.8 dB and 65 dB for the each method. These SOMs present improved linearity compared to that without the second harmonic injection because IMD3s are improved by 18. dB and 21 dB for each method.

• Journal of Power Electronics
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• v.18 no.2
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• pp.604-614
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• 2018

This paper proposes a synchronous switching technique for a Vienna rectifier that uses carrier-based pulse width modulation (CB-PWM). A three-phase Vienna rectifier, similar to a three-level T-type converter with three back-to-back switches, is used as a PWM rectifier. Conventional CB-PWM requires six independent gate signals to operate back-to-back switches. When internal switches are operated synchronously, only three independent gate signals are required, which simplifies the construction of gate driver circuits. However, with this method, total harmonic distortion of the input current is higher than that with conventional CB-PWM switching. A reactive current injection technique is proposed to improve current distortion. The performance of the proposed synchronous switching method and the effectiveness of the reactive current injection technique are verified using simulations and experiments performed with a set of Vienna rectifiers rated at 5 kW.

• Journal of Power Electronics
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• v.13 no.4
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• pp.719-728
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• 2013

A novel hybrid active power filter (NHAPF) that can be adopted in high-voltage systems is proposed in this paper. The topological structure and filtering principle of the compensating system is provided and analyzed, respectively. Different controlling strategies are also presented to select the suitable strategy for the compensation system. Based on the selected strategy, the harmonic suppression function is used to analyze the influence of system parameters on the compensating system with MATLAB. Moreover, parameters in the injection branch are designed and analyzed. The performance of the proposed NHAPF in harmonic suppression and reactive power compensation is simulated with PSim. Thereafter, the overall control method is proposed. Simulation analysis and real experiments show that the proposed NHAPF exhibits good harmonic suppression and reactive power compensation. The proposed compensated system is based on the three-phase four-switch inverter, which is inexpensive, and the control method is verified for validity and effectiveness.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1236-1238
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• 2000

This paper considers the problem of eliminating harmonics in the inverter output waveforms. The approach is based on the minimization of the current harmonics in the induction motor by space vector modulation method. Reference voltage is compensated with injection of controlled current harmonics which are calculated to reduce current harmonics through sampled current harmonic analyzing algorithm. The theoretical analysis is carried out using computer simulation. It is verified that proposed SVM technique could reduce current harmonic component and improve THD.

• Journal of IKEEE
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• v.26 no.1
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• pp.95-103
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• 2022

In this paper, the efficiency of a sensorless method with square-wave injection for a low-cost inverter, so called B4 inverter is presented. This inverter comprises only 4 switches to reduce system cost. It is distinguished from the conventional B6 inverter that has 6 of switching elements. The B4 inverter, injected a 1 kHz of harmonic wave, has been modelled using the functions and library in Matlab/Simulink. This paper described each component of sensorless algorithm. Among them, the Notch Filter is used to extract the harmonic component of the phase current and a second-order low-pass filter was used to reduce the ripple of the estimated speed. It is shown through simulation that the rotor angle of a permanent magnet synchronous motor is detected by multiplying the current waveform extracted using the notch filter by the harmonic voltage. The feasibility of the proposed method is shown through Simulink simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.59-65
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• 2018

A new single-stage flyback power converter with PFC for electrolytic capacitor-less LED driver is proposed in this study. This method minimizes the peak-to-average ratio of the LED driving pulsating current by adding the LED driving current near the LED current valley area, as well as the third harmonic component injection into the input current. The reduced peak current value of the LED drive current minimizes the thermal stress of the LED itself, thereby increasing the reliability of the LED, as well as achieving a long lifetime. Simulation and experimental results show the usefulness of the proposed topology.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.451-455
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• 1991

The PWM control technique is proposed which can eliminate the harmonic components of the nonsinusoidal ac line current such as the current of 6-phase rectifier by injecting PWM current. TSC(Time-Sharing Control) is adopted to avoid the unbalance between three PWM injection currents at the three-phase system. Also a new power circuit for three-phase filter is suggested for realizing the proposed PWM control technique. The operation characteristics are investigated theoretically and experimentally to show the feasibility of the optimized injection method.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.269-272
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• 2003

A low phase noise frequency synthesizer at X-Band which employs the subharmonic injection locking was designed and tested. The frequency synthesizer consists of two oscillators - master and slave : A 1.75GHz master oscillator made of PLL synthesizer produces 6th harmonic at 10.5GHz, which excites the following 10.5GHz slave oscillator. The realized frequency synthesizer has a 4.5dBm of output power, and a phase noise of -108dBc/Hz at the 100kHz offset frequency.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.24 no.2
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• pp.112-117
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• 2013

Background and Objectives : This study aimed to determine the clinical effect of $Artecoll^{(R)}$ injection laryngoplasty for patients with vocal atrophy and mild sulcus vocalis. Materials and Method : Forty-one patients with vocal atrophy and/or mild sulcus vocalis received transcutaneous $Artecoll^{(R)}$ injection into the vocal folds under local anesthesia. Subjective evaluations including voice handicap index (VHI) and perceptual grading with Grade, Roughness, Breathiness, Asthenia, Strain (GRBAS) scales and objective evaluations including jitter, shimmer, noise-to-harmonic ratio (NHR), speaking fundamental frequency (SFF) and maximum phonation time (MPT) were evaluated before and 3 months after the injection. Results : VHI and Grade, Breathiness and Strain scales in GRBAS showed significant improvement 3 months after injection. SFF and MPT also significantly improved after the injection ; MPT increased and SFF in male patients decreased. Conclusion : Injection laryngoplasty with $Artecoll^{(R)}$ is an effective method for correcting the glottal insufficiency and improving voice quality in patients with vocal atrophy and/or mild sulcus.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.1076-1081
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• 2003

A new technique for generating millimeter-wave signals from a semiconductor laser is presented. The method multiples the signal frequency by using optical injection of short optical pulses at a sub-harmonic of the cavity round-trip frequency to drive the laser oscillating at its resonant frequency. A 32GHz signal is generated using a multisection semiconductor laser operated under continuous wave conditions, by injection optical pulses at a repetition rate equal to the fourth subhamonic(8GHz). The generated millimeter-wave signal exhibits a large submamonic suppression ratio(＞17 dB), large frequency detuning range (>300 MHz) low levels of phase-noise(-77.5 dBc/Hz), and large locking (>400 MHz)