• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.8
• /
• pp.1355-1361
• /
• 2016

The inter-turn fault (ITF) causes the negative sequence components in the d -q voltage equation due to an increase in the unbalance of three-phase input currents. For this reason, d -q voltage equation become complicate as the voltage equation is classified into positive and negative components. In this study, we propose a simplified d -q equivalent circuit of an interior permanent magnet synchronous motor under ITF state. First, we proposed modeling method for d -q current based on the finite element method simulation results. Then, we developed the simplified d -q equivalent circuit by applying the proposed d -q current modeling.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.49 no.9
• /
• pp.43-48
• /
• 2012

This paper presents an iterative single-frequency continuous-wave signal-based I/Q regeneration method for improving image-rejection performance of multi-port junction-based direct receivers (MPDRs). This paper analyzes I/Q regeneration in MPDRs as I/Q mismatch compensation for direct conversion receivers. Based on the analysis, this paper evaluates the accuracy of I/Q regeneration in terms of the image-rejection ratio (IRR). The proposed method improves the IRR performance more than 20 dB compared to existing I/Q regeneration methods. Simulation results show that MPDRs using the proposed method can achieve an IRR of more than 70 dB, and that the bit error rate performances are almost the same as those of conventional coherent demodulators, even in fading channels.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.1
• /
• pp.45-52
• /
• 2021

The space vector control based voltage control method for a three-phase PWM rectifier requires a lot of effort to design an optimal switching pattern since a switching pattern for the switching section must be designed. In this study, a D-Q control based SPWM output voltage control algorithm was studied for the three-phase six-pulse CVS type rectifier. In the output voltage control algorithm, three-phase reference signals are obtained from the D-Q transformation based on the space vector representation method, instead of the switching pattern, SPWM method is used to generate rectifier switching control signals. Next, a three-phase six-pulse CVS PWM rectifier based on D-Q transformation and SPWM was modeled using EMTP-RV. Finally, the validity of the D-Q control-based SPWM voltage control algorithm was confirmed by comparing the output voltage waveform obtained through EMTP-RV simulation works with a reference value and confirming that the output voltage accurately follows the reference voltage.

• Journal of the Korean Society of Safety
• /
• v.13 no.3
• /
• pp.163-170
• /
• 1998

The differential quadrature method (D.Q.M.) is applied to computation of eigenvalues of small-amplitude free vibration for horizontally curved beams including a warping contribution. Fundamental frequencies are calculated for a single-span, curved, wide-flange beam with both ends simply supported or clamped, or simply supported-clamped end conditions. The results are compared with existing exact solutions and numerical solutions by other methods for cases in which they are available. The differential quadrature method gives good accuracy even when only a limited number of grid points is used.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.1
• /
• pp.54-60
• /
• 2020

A digital current control scheme using virtual d-q transformation for a boost single-phase power factor correction (PFC) converter is proposed. The use of virtual d-q transformation in single-phase power converters is known to improve current control performance. However, the conventional virtual d-q transformation-based digital current control scheme cannot be directly applied to the boost single-phase PFC converter because the current and average voltage waveforms of the inductor used in the converter are not sinusoidal. To cope with this problem, this study proposes a virtual sinusoidal signal generation method that converts the current and average voltage waveform of the inductor into a sinusoidal waveform synchronized with the grid. Simulation and experimental results are provided to show that the virtual d-q transformation-based digital current control is successfully applied to the boost single-phase PFC converter with the aid of the proposed virtual sinusoidal signal generation method.

• Bulletin of the Korean Mathematical Society
• /
• v.60 no.5
• /
• pp.1237-1252
• /
• 2023

A fundamental problem in coding theory is to find n_q(k, d), the minimum length n for which an [n, k, d]_q code exists. We show that some q-divisible optimal linear codes of dimension 4 over 𝔽_q, which are not of Belov type, can be constructed geometrically using hyperbolic quadrics in PG(3, q). We also construct some new linear codes over 𝔽_q with q = 7, 8, which determine n₇(4, d) for 31 values of d and n₈(4, d) for 40 values of d.

• Journal of Magnetics
• /
• v.17 no.4
• /
• pp.280-284
• /
• 2012

This paper presents a method for evaluating interior permanent magnet synchronous motor (IPMSM) performance over the entire operation region. Using a d-q axis equivalent circuit model consisting of motor parameters such as the permanent magnetic flux, copper resistance, core loss resistance, and d-q axis inductance, a conventional mathematical model of an IPMSM has been developed. It is well understood that in IPMSMs, magnetic operating conditions cause cross saturation and that the iron loss resistance - upon which core losses depend - changes according to the motor speed; for the sake of convenience, however, d-q axis machine models usually neglect the influence of magnetic cross saturation and assume that the iron loss resistance is constant. This paper proposes an analysis method based on considering a magnetic cross saturation and estimating a core loss resistance that changes with the operating conditions and speed. The proposed method is then verified by means of a comparison between the computed and the experimental results.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.509-512
• /
• 2007

In this paper, we report our successful implementation of Q tensor model in threedimensional finite element method (FEM) simulator. The 3D-FEM Q tensor-model-based simulation revealed that the spaly-to-bend transition occurs only at 4 V while the vector-model based FEM solver provides an erroneous transition voltage of 8 V.

• Journal of Power Electronics
• /
• v.8 no.1
• /
• pp.91-100
• /
• 2008

The d-q harmonic detecting algorithms are dominant methods to generate current references for active power filters (APF). They are often implemented in the synchronous frame and time domain. This paper researches the frequency characteristics of d-q synchronous transformations, which are closely related to the analysis and design issues of control system. Intuitively, the synchronous transformation is explained with amplitude modulation (AM) in this paper. Then, the synchronous filter is proven to be a time-invariant and linear system, and its transfer function matrix is derived in the stationary frames. These frequency-domain models imply that the synchronous transformation has an equivalent effect of frequency transformation. It is because of this feature, the d-q method achieves band-pass characteristics with the low pass filters in the synchronous frame at run time. To simplify these analytical models, an instantaneous positive-negative sequence frame is proposed as expansion of traditional symmetrical components theory. Furthermore, the synchronous filter is compared with the traditional bind-pass filters based on these frequency-domain analytical models. The d-q harmonic detection methods are also improved to eliminate the inherent coupling effect of synchronous transformation. Typical examples are given to verify previous analysis and comparison. Simulation and experimental results are also provided for verification.

• International Journal of Automotive Technology
• /
• v.8 no.4
• /
• pp.493-504
• /
• 2007

This paper proposes a stereo vision-based forward obstacle detection and distance measurement method. In general, stereo vision-based obstacle detection methods in automotive applications can be classified into two categories: IPM (Inverse Perspective Mapping)-based and disparity histogram-based. The existing disparity histogram-based method was developed for stop-and-go applications. The proposed method extends the scope of the disparity histogram-based method to highway applications by 1) replacing the fixed rectangular ROI (Region Of Interest) with the traveling lane-based ROI, and 2) replacing the peak detection with a constant threshold with peak detection using the threshold-line and peakness evaluation. In order to increase the true positive rate while decreasing the false positive rate, multiple candidate peaks were generated and then verified by the edge feature correlation method. By testing the proposed method with images captured on the highway, it was shown that the proposed method was able to overcome problems in previous implementations while being applied successfully to highway collision warning/avoidance conditions, In addition, comparisons with laser radar showed that vision sensors with a wider FOV (Field Of View) provided faster responses to cutting-in vehicles. Finally, we integrated the proposed method into a longitudinal collision avoidance system. Experimental results showed that activated braking by risk assessment using the state of the ego-vehicle and measuring the distance to upcoming obstacles could successfully prevent collisions.