• Journal of Electrical Engineering and Technology
• /
• 제10권1호
• /
• pp.271-279
• /
• 2015

Induction cooking application with multiple loads need high power inverters and appropriate control techniques. This paper proposes an inverter configuration with buck-boost converter for multiple load induction cooking application with independent control of each load. It uses one half-bridge for each load. For a given dc supply of $V_{DC}$, one more $V_{DC}$ is derived using buck-boost converter giving $2V_{DC}$ as the input to each half-bridge inverter. Series resonant loads are connected between the centre point of $2V_{DC}$ and each half-bridge. The output voltage across each load is like that of a full-bridge inverter. In the proposed configuration, half of the output power is supplied to each load directly from the source and remaining half of the output power is supplied to each load through buck-boost converter. With buck-boost converter, each half-bridge inverter output power is increased to a full-bridge inverter output power level. Each half-bridge is operated with constant and same switching frequency with asymmetrical duty cycle (ADC) control technique. By ADC, output power of each load is independently controlled. This configuration also offers reduced component count. The proposed inverter configuration is simulated and experimentally verified with two loads. Simulation and experimental results are in good agreement. This configuration can be extended to multiple loads.

• 전기학회논문지
• /
• 제58권4호
• /
• pp.832-839
• /
• 2009

In this paper, we introduce an design of fuzzy relation-based fuzzy neural networks with multi-output. Fuzzy relation-based fuzzy neural networks comprise the network structure generated by dividing the entire input space. The premise part of the fuzzy rules of the network reflects the relation of the division space for the entire input space and the consequent part of the fuzzy rules expresses three types of polynomial functions such as constant, linear, and modified quadratic. For the multi-output structure the neurons in the output layer were connected with connection weights. The learning of fuzzy neural networks is realized by adjusting connections of the neurons both in the consequent part of the fuzzy rules and in the output layer, and it follows a back-propagation algorithm. In addition, in order to optimize the network, the parameters of the network such as apexes of membership functions, learning rate and momentum coefficient are automatically optimized by using real-coded genetic algorithm. Two examples are included to evaluate the performance of the proposed network.

• 조명전기설비학회논문지
• /
• 제13권4호
• /
• pp.134-141
• /
• 1999

본 논문은 전동차량용 전원장치의 출력전압 제어 안정성을 향상시키기 위한 연구이다. 입력전압 변동 및 부하 변동 등 과도상태시 출력 정전압 제어를 수행할 경우, L-C 필터부에서 공진이 발생함으로써 출력전압이 흔들리고 시스템이 불안해진다. 본 논문에서, 출력전압제어의 안정성을 확보하기 위해 주필터부에 공진을 억제하는 댐핑회로를 새롭게 제안하고, 이에 적합한 제어방법을 소개한다. 제안한 댐핑회로는 R-L로서 소형이고 간단히 구성된다. 제어기에는 과도상태분의 궤환제어와 대역저지필터를 적용한다. 또한 전력회로는 3레벨 PWM방식을 적용하였다. 이로서 과도상태에서 출력전압의 흔들림없이 변동폭을 10[%]이하로 제어할 수 있었으며, 정상상태의 출력 전압 왜형율도 3[%]이하로 감소시켰다.

• Journal of Power Electronics
• /
• 제5권2호
• /
• pp.151-159
• /
• 2005

The errors generated from current measurement paths are inevitable, and they can be divided into two categories: offset error and scaling error. The current data including these errors cause periodic speed ripples which are one and two times the stator electrical frequency respectively. Since these undesirable ripples bring about harmful influences to motor driving systems, a compensation algorithm must be introduced to the control algorithm of the motor drive. In this paper, a new compensation algorithm is proposed. The signal of the integrator output of the d-axis current regulator is chosen and processed to compensate for the current measurement errors. Usually the d-axis current command is zero or constant to acquire the maximum torque or unity power factor in the ac drive system, and the output of the d-axis current regulator is nearly zero or constant as well. If the stator currents include the offset and scaling errors, the respective motor speed produces a ripple related to one and two times the stator electrical frequency, and the signal of the integrator output of the d-axis current regulator also produces the ripple as the motor speed does. The compensation of the current measurement errors is easily implemented to smooth the signal of the integrator output of the d-axis current regulator by subtracting the DC offset value or rescaling the gain of the hall sensor. Therefore, the proposed algorithm has several features: the robustness in the variation of the mechanical parameters, the application of the steady and transient state, the ease of implementation, and less computation time. The MATLAB simulation and experimental results are shown in order to verify the validity of the proposed current compensating algorithm.

• 조명전기설비학회논문지
• /
• 제19권7호
• /
• pp.113-121
• /
• 2005

본 논문에서는 오존발생장치의 전원측 파형에 포함되는 고주파수의 노이즈를 제거하고, 디지털 궤환 제어에 의해 오존 출력을 제어하기 위하여 전원장치의 출력측 LC 필터와 방전관 용량으로부터 커패시터 전압과 전류를 검출하여 2중의 제어루프를 설계하였다. 디지털 제어기의 연산지연시간을 보상하기 위하여 연산지연시간을 전원장치 플랜트의 고유한 파라미터로 가정하고, 플랜트 모델에 포함시켜 모델링 하였다. 오존발생장치의 부하변동에 따르는 과도상태 응답특성을 개선하고, 파라미터 변동에 강인한 특성을 얻기 위하여 내부 전류 모델 제어기를 제안하였다. 또한 오존발생장치용 전원장치에서 영 오차의 정상 상태를 얻기 위하여 외부 전압 제어루프를 구성하여 비례 제어기와 공진 제어기를 병렬로 연결한 비례-공진 전압제어기를 제안하였다.

• 전기학회논문지P
• /
• 제51권3호
• /
• pp.120-125
• /
• 2002

The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. In the switching-mode power converter, the output voltage is generally controlled by varying the duty ratio of main switch. When a converter operates in steady state, duty ratio of the converter is kept constant. So the power of switching noise is concentrated in specific frequencies. Generally, to reduce the EMI and improve the immunity of converter system, the switching frequency of converter needs to be properly modulated during a rectified line period instead of being kept constant. Random Pulse Width Modulation (RPWM) is performed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300V/1kW with 5%~30% white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.

• 전자공학회논문지SC
• /
• 제37권2호
• /
• pp.29-36
• /
• 2000

본 논문에서는 트랜지스터 동작영역에 독립적인 일정 트랜스컨덕턴스 rail-to-tail 입력회로 및 AB-급 출력회로를 갖는 2단 연산증폭기를 제시한다. rail-to-rail 입력회로는 추가 NMOS 및 PMOS 차동 입력단 구조를 사용하여, 전체 동상 입력 전압에서 항상 일정한 트랜스컨덕턴스를 갖도록 하였다. 이러한 입력단 회로는 기존 MOS의 정확한 전류-전압 관계식을 사용하지 않고, 트랜지스터의 동작영역에서, 즉 강 반전 및 약 반전, 독립적인 새로운 광역 선형 전류관계를 제안한다. 본 논문에서 제안한 입력단 회로를 SPICE를 사용하여 모의실험 결과, 전체 동상 입력 전압에 대해서 4.3%의 변화율이 나타남을 검증하였다. AB-급 출력단 회로는 공급 전압원에 독립적인 일정한 동작 전류값을 갖고, 출력 전압은 Vss+0.1에서 Vdd-0.15까지 구동하는 전압 특성을 나타내었다. 또한 출력단은 AB-급 궤환 제어 방식을 사용하여 저전압에서 동작 할 수 있다. 전체 연산 증폭기의 단일-이득 주파수 및 DC 전압이득 변화율은 각각 4.2% 및 12%로 나타냈다.

• The Korean Journal of Physiology
• /
• 제8권2호
• /
• pp.19-31
• /
• 1974

In oder to study the correlation between daily urinary output of sodium chloride and blood pressure, twenty four hour urine samples were collected from 224 cases (70 male and 154 female) of healthy Koreans whose age varied from 18 to 70 years old. The volume and concentration of sodium, chloride and potassium and total nitrogen were measured, along with the resting blood pressure. Results obtained are summarized as follows; 1. Daily urinary output was increased as a function of age. However, daily urinary output per unit sulface area was maintained at approximately 800 to 900 $ml/m^2$ in all age groups of male and it increased as a function of age in female groups. There was no significant difference between male and female. 2. The daily urinary sodium concentration was decreased gradually acceding to age in both sexes. Daily excretion of sodium was constant regardless of age in both sexes but especially high in 25-39 year female age group, which was slightly greater in males than in females. 3. The daily urinary chloride concentration was at approximately 250 meq/L in all age groups of male and which decreased as a function of age in females. 4. Hence the daily urinary output of sodium chloride was constant in all age groups of males which increased as a function of age in female groups. However, daily excretion of sodium chloride per unit sulface area was maintained at approximately 11 $gm/m^2$ in males and which increased as a function of age in females. 5. The daily urinary excretion of potassium was constant regardless of age in both sexes. 6. Urinary K/Na ratio was maintained at approximately 0.27 in males and 0.33 in females. 7. The daily urinary output of total nitrogen amount was approximately $8{\sim}10$ gm in males and $7{\sim}9$ gm in females. However, daily urinary output of nitrogen per unit sulface area was constant regardless of age in both sexes. 8. The systolic blood pressure was increased gradually according to the age in both sexes and was higher for males than females under 40 years of age. However, there was no significant difference between both sexes in ages over 40 years. 9. Quantitative comparisons indicated that daily urinary output and sodium chloride excretion are higher while daily potassium output, nitrogen excretion and urinary K/Na ratio are significantly lower among Koreans than a among Occidentals. These findings suggest that average Koreans live on low-protein and high-salt diet throughout their livers. Statistical result obtained may he summarized as follows; 10. The relation between blood pressure and sodium concentration of urine. The correlation between systolic blood pressure and sodium concentration was negatively associated for both sexes and the correlation coefficient was significant for females $({\gamma}_1=-.19<-{\gamma}_{152},\;_{0.05}=-0.159)$ and it was not significant for males $({\gamma}_1=-.19>-{\gamma}_{68},\;_{0.05}=-0.232)$ tut may be due to the sample size for males. The correlation between diastolic blood Pressure and sodium concentration was negatively associated for both sexes and the correlation coefficient was significant for males $({\gamma}_1=-.37<-{\gamma}_{68},\;0.05=-0.232)$ and the relation was not significant for females $({\gamma}_1=-.11>-{\gamma}_{152},\;_{0.05}=-0.159)$. 11. The relation between blood pressure and daily urinary sodium chloride excretion. The association between systolic blood pressure and sodium chloride excretion was positively correlated for both sexes and the relation was significant for females $({\gamma}_1=.20>{\gamma}_{152},\;_{0.05}= 0.159)$ and it was insignificant for males $({\gamma}_1=.09<{\gamma}_{68},\;_{0.05}=0.232)$, The relation between diastolic blood pressure and sodium chloride excretion was positively associated and insignificant for both sexes males $({\gamma}_1=.17<{\gamma}_{68},\;_{0.05}=0.232)$ and females $({\gamma}_1=.09<{\gamma}_{152},\;_{0.05}=0. 159)$. 12. The relation between daily urinary nitrogen excretion and sodium chloride excretion. The association between daily nitrogen excretion and sodium chloride excretion was positively significant for both sexes, males $({\gamma}_1=.31>{\gamma}\;_{68},\;_{0.05}=0.232)$ and females $({\gamma}_1=.36>{\gamma}_{-152},\;_{0.05}=0.159)$.

• 전기학회논문지
• /
• 제60권6호
• /
• pp.1152-1162
• /
• 2011

In this paper, a single-phase DC-AC inverter using two embedded Z-source converters is proposed. The proposed inverter is composed of two embedded Z-source converters with common DC source and output AC load. The output AC voltage of the inverter is obtained by the difference of output capacitor voltages of each converter. The output voltage of each converter take shape of the asymmetrical AC waveform centering zero voltage. Therefore, the proposed inverter can generate the same output voltage despite low VA rating L-C elements, compared to the conventional inverter using high DC voltage with AC ripple. To verify the validity of the proposed system, the PSIM simulation was achieved under the condition of rapid increase of DC source (110[V]${\rightarrow}$150[V]) and R-load (50[${\Omega}$]${\rightarrow}$300[${\Omega}$]). For controlling the voltage of the inverter system, the one-cycle controller was adopted. As results, the proposed inverter output the constant AC voltage (220[V]rms/60[Hz]) for all conditions. Also, the R-L load and nonlinear diode load were adopted for the proposed inverter loads, and we could know that the its output voltage characteristics were as good as the pure R-load. Finally, the RMS and THD of output AC voltage were examined for the different loads, input DC voltages and reference voltage signals.

• 제어로봇시스템학회논문지
• /
• 제22권3호
• /
• pp.233-240
• /
• 2016

This paper describes a three-dimensional reference trajectory generation method for giving commands to an unmanned air vehicle (UAV). The trajectory is a set of consecutive curves with constant acceleration during each interval and passing through via-points at specified times or speeds. The functional inputs are three-dimensional positions and times (or speeds) at via-points, and velocities at both boundaries. Its output is the time series of position values satisfying the piecewise constant acceleration condition. To be specific, the shape of the trajectory, known as the path, is first represented by splines using third degree polynomials. A numeric algorithm is then suggested, which can overcome the demerits of cubic spline method and promptly generate a piecewise constant acceleration trajectory from the given path. To show the effectiveness of the present scheme, trajectory generation cases were treated, and their speed calculation errors were evaluated.