Advanced Engineering Forum Vol. 38

Abstract: A phase difference image using phase-shifting digital holography, which is applied for non-contact shape measurement, contains speckle noises and filtering to reduce them is inevitable for its application. We have developed a new filter which causes less deformation than commonly used filters.

Abstract: In general, we need a lot of data for improving the accuracy of machine learning. However, the number of biological samples what we can obtain are not enough for machine learning. This problem exists in the classification of glomerular epithelial cells with the progress of disease, and its accuracy is contrary to our intuitive impression. Therefore, we would like to improve the accuracy by generating a lot of fake images using Generative Adversarial Nets (GANs). About podocyte cells, it was difficult to obtain an arbitrary disease by previous method. In this paper, we propose the model with restriction of learning by shapes information based on ACGANs, and we investigate how much fake images generated by our method are similar to real images. According to the results, the passage number of fake images by our method is 17% higher than conventional method.

Abstract: This paper describes two algorithms for generating test signals to efficiently test the linearity of ADCs. Linearity is an important testing item for ADCs, and it takes a long time (hence is costly) to test especially low-sampling-rate, high-resolution ADCs. We have proposed to generate a test signal consisting of multiple-sine waves, to precisely test the linearity for specific important codes (such as around the center of the output codes), using an arbitrary waveform generator (AWG) and an analog filter in our previous studies. Here, we formulate them for general use. Their verification is performed on a single sine wave, and good results are obtained to show the validity of the derivation algorithm.

Abstract: We developed the photon counting CT system by using a conventional laboratory X-ray source and a CdTe line sensor. Attenuation coefficients were obtained from the measured CT image data. Our suggested method for deriving the electron density and effective atomic number from the measured attenuation coefficients was tested experimentally. The accuracy of the electron densities and effective atomic numbers are about <5 % (the averages of absolute values are 2.6 % and 3.1 %, respectively) for material of 6< Z and Zeff <13. Our suggested simple method, in which we do not need the exact source X-ray spectrum and detector response function, achieves comparable accuracy to the previous reports.

Abstract: This paper proposes the method of the Electro-Magnetic Interference (EMI) noise reduction of the AC-DC rectifiers and the DC-DC converters with the insulated transformers. For the Power Factor Correction (PFC) rectifier, the power factor is the most important item, but the EMI noise emitted from the clock pulse is not remarked. For the DC-DC converters such as the forward converter, the efficiency is the most important. We have focused on the EMI noise reduction for the PFC rectifier and insulated DC-DC converters with the frequency modulation of the clock pulses. First, the spectrum level of the clock pulse is introduced to be much reduced by shaking the clock frequency for the PFC rectifier and the forward converter. Next, we have investigated the EMI reduction of the LLC converter whose operating frequency varies to make the output voltage stable. It is difficult to modify the operating frequency to reduce the EMI noise. We have investigated to reduce the EMI noise by shaking the duty ratio of the resonant signals for the LLC converter. In this case, the output voltage ripple is increased by much EMI noise reduction. Finally, the technology to stabilize the increased ripple is introduced.

Abstract: This paper proposes a new technology about generating notch characteristics in noise spectrum of DC-DC switching converters for the communication devices. There are very few reports about the pulse coding controlled switching converter, though it is sometimes used in digital-to-analog converter (DAC) field, to our knowledge. We have investigated the pulse coding technology to switching converters to generate automatically the notch characteristics in the noise spectrum. The notch frequency Fn in the spectrum of the switching pulses is created by two coding pulses to control the main power switch. The clock and coding pulses are automatically generated from the input frequency Fin to create the notch frequency Fn=Fin. In addition, the notch frequency is experimentally confirmed with the prototype circuit.

Abstract: This paper proposes a new EMI reduction and automatic ripple cancellation technique about the ripple-controlled converter with the ripple injection and Constant-On Time (COT) method. The ripple-controlled converters have no stable clock and it is difficult to reduce the EMI noise by shaking the operating frequency. The new method of EMI reduction is that the COT pulse width is modulated by the triangular signal so that the operating frequency is modulated and the spectrum peak level of the clock frequency is greatly reduced. But the output voltage ripple is much increased because of the change of the duty ratio of the operating frequency. The increaced ripple is canceled by adding the modulation signal to the ripple injection circuit. Moreover stabiliztion of the operating frequency on Discontinuous Conduction Mode (DCM) is reported. The operating frequency falls down on DCM mode in the COT converters. To stabilize the operating frequency, cheking the operating period is fedback to control the COT pulse width

Abstract: This paper proposes a new multi-phase switching converter with atuotomatic current barance technique. It is well-known that the multi-phase switching converter is suitable to handle large output current with small output voltage ripple for the buck converters which use the clock pulse. This paper investigates a multi-phase controlled method for the ripple-controlled converters and the soft switching converters, that use no clock pulse; for this reason, these converters are difficult to realize multi-phase converter configurations. There are some multi-phase hysteretic controlled converters; they utilize a main clock generator or an external sub-clock pulse, which has the master-slave synchronization method. But it is difficult to respond to a frequency change of the master converter. These multi-phase converters have not considered the imbalance among phase currents caused by variations of inductors and semiconductor switches in the power stage. For the commercialized multi-phase Voltage Regulating Modules (VRMs), the inductors and the semiconductor switches are selected to adjust the balance among the phase currents. However, there is no multi-phase soft switching converter.Then we have developed the multi-phase ripple-controlled converter and the multi-phase soft switching converter with the technique of detecting 180-degree from the variable operating frequency of the main converter. Moreover, in these converters, there appears the current imbalance because of the element variations among inductors and capacitors, if some cares are not taken there. Then we have developed the automatic correction for the current imbalance by modifying the width of the Constant On Time (COT) pulse or modifying the slope of the saw-tooth signal.

Abstract: This paper proposes new EMI reduction technologies and automatic output voltage ripple cancellation method for the PWM buck converter with voltage-mode or current-mode and the ripple-controlled converters. Genenrally, modfying the clock frequeny is effective to reduce the EMI noise, but it may increase the output ripple substantially. We have developed techniques to cancel the increased ripple by modifying the slope of the saw-tooth signal or current of the ripple injection circuit. The EMI spectrum of the operating frequency is reduced by more than 15dB and the modified large ripple is canceled to the stable level.

Abstract: This paper proposes an EMI spread spectrum technology with automatically setting the notch frequency using the pulse coding controlled method of the DC-DC switching converter. In the automatic notch generation method, by usage of the input frequency F_in, the clock frequency F_ck and the coding pulses P_H, P_L are generated automatically using the equation (see formula in the paper). Here the conversion voltage ratio is given by (see formula in the paper) . If shifts, the balance of the inductor current is shifted and then the output voltage ripple is influenced. Moreover, as the power supply IC, it is necessary to automatically detect or set the conditions for V_in and V_out, and hence we also provide discussion about the conversion voltage ratio D_o in many situations.