This paper proposes a new circuit topology for a high efficiency isolated DC/DC converter using series compensation. The proposed converter consists of a high efficiency resonance half-bridge converter and a series converter. The series converter regulates the output voltage the provides only the differential voltage between the input voltage and output voltage. Therefore, the circuit achieves high efficiency when the input voltage is almost equal to the output voltage, because then only the resonance converter will operate. In this paper, the approach employed to achieve a high efficiency by using the proposed series compensation method is introduced. In addition, the fundamental operation and the method of designing the proposed circuit are described. The suitability of the proposed circuit was confirmed by performing an experiment and loss analysis, maximum efficiency achieved was 96.2%.
This paper presents an electronic ballast system with lamp rating detection capability. From the experimentally obtained operating frequency of the lamps, a possibility weight is constructed to help facilitate the lamp classification. The proposed detection algorithm employs a multi-step lamp power regulation algorithm where decision making is based on the sensed frequency and the possibility weight. Simulation and experimental results show that the proposed detection method can successfully detect the targeted lamp power rating and deliver the desired power to the lamp.
The servo system of a permanent magnet (PM) motor should always maintain fine torque and fine speed responses. Accurate motor parameter identification is necessary for the PM motor servo system because the current control system is designed by considering the electric parameters of the PM motor. However, the motor parameters vary with the age of the motor and temperature. Moreover, current sensors have offset values. When the current sensor has offset values, the PM motor servo system produces torque ripple. In order to overcome these problems, this paper proposes a new real-time estimation method for both current sensor offsets and electrical parameters (resistance Ra, inductance La, and magnetic flux φfa) of the surface permanent magnet (SPM) motor. The proposed method involves the use of a real-time algorithm and a current simulator, which is operated using a DSP software system. In order to accurately estimate the motor parametera, the proposed method is using estimate currents, DC terms of sensor currents, and nominal motor parameter value. The experimental results of this study confirm that the proposed method satisfactorily estimates the current sensor offset of the U phase and V phase, as well as the electrical motor parametersRa, La, and φfa accurately.
Series connections of energy-storage modules such as electric double-layer capacitors (EDLCs) and lithium-ion batteries result in voltage imbalance because of the nonuniform properties of individual modules. Conventional voltage equalizers based on traditional dc-dc converters require numerous switches and/or transformers, and therefore, their costs and complexity tend to increase. This paper proposes a novel single-switch equalization charger using multiple stacked buck-boost converters. The single-switch operation not only reduces the circuit complexity but also contributes to increasing the reliability. The fundamental operating principles and design procedures of key components are presented in detail. An experimental charge test using a 25W prototype of the proposed equalization charger was performed for four series-connected EDLC modules whose initial voltages were intentionally imbalanced. Experimental results demonstrated that the proposed equalization charger could charge the series-connected modules preferentially in the order of increasing module voltage and that all the modules could be charged up to a uniform voltage level.
A parallel computing method for rotating machines excited by the voltage source with the three-dimensional finite element method is developed. In this method, the matrix equations which contains voltage equations are divided into multiple subdomains and the matrix-vector products for the voltage equations in each subdomain are calculated efficiently. The validity and the usefulness of the method are verified through the computation of an IPM motor with the off-centered rotor on the Earth Simulator.
Automotive industry is considered to be one of the main contributors to environmental pollution and global warming. Therefore, many car manufacturers are in near future planning to introduce hybrid electric vehicles (HEV), fuel cell electric vehicles (FCEV) and pure electric vehicles (EV) to make our cars more environmentally friendly. These new vehicles require highly efficient and small power converters. In recent years, considerable improvements were made in designing such converters. In this paper, an approach based on so called Snubber Assisted Zero Voltage and Zero Current Switching topology otherwise also known as SAZZ is presented. This topology has evolved to be one of the leaders in the field of highly efficient converters with high power densities. Evolution and main features of this topology are briefly discussed. Capabilities of the topology are demonstrated on two case study prototypes based on different design approaches. The prototypes are designed to be fully bi-directional for peak power output of 30kW. Both designs reached efficiencies close to 99% in wide load range. Power densities over 40kW/litre are attainable in the same time. Combination of MOSFET technology and SAZZ topology is shown to be very beneficial to converters designed for EV applications.
Many research groups are developing series voltage compensators. In the series converter, since a transformer is used in series in the power system, the power system current flows into the voltage source inverter through the transformer. The inverter current, which is determined by the transformation ratio, gives rise to an error voltage that consists of a dead-time voltage and an impedance voltage; the error voltage is generated even when the reference voltage is zero. This paper describes the generation mechanism of the error voltage and proposes a method for reducing the error voltage.
Several researchers have reported the regression tree analysis for semiconductor yield. However, the scope of these analyses is restricted by the difficulty involved in applying the regression tree analysis to a small number of samples with many attributes. It is often observed that splitting attributes in the route node do not indicate the hypothesized causes of failure. We propose a method for verifying the hypothesized causes of failure, which reduces the number of verification hypotheses. Our method involves selecting sets of analysis data with the same cause of failure, extracting the hypothesis by applying the regression tree analysis separately to each set of analysis data, and merging and sorting attributes according to the t value. The results of an experiment conducted in a real environment show that the proposed method helps in widening the scope of applicability of the regression tree analysis for semiconductor yield.
This paper describes the dynamic analysis method of a three degree-of-freedom electromagnetic spherical actuator considering the mutual effect among X-, Y- and Z-axis employing the 3-D finite element method, in which the magnetic field equation is fully combined with equations of electric circuit and motion. The validity of the analysis is confirmed by comparing with the measured results on a prototype.
This paper presents a simple and energy-saving method for controlling hybrid powered railway vehicles that run on rural non-electrified railway lines and have diesel engine and electrical double layer capacitors (EDLCs). The aim this study is to reduce both the fuel consumption and the capacitance of EDLCs. A basic idea proposed in this paper is that EDLCs supply and absorb the kinetic energy of the vehicle and the engine output compensates supply the energy loss with the vehicle running. Thus, the energy loss is not taken into consideration while expressing the EDLC voltage reference (equation 1); energy loss is considered when the engine is in operating mode. The proposed method is examined by performing numerical simulations for various values of engine operation time, load, and grade section. The results of this study reveal the relationship between the capacitance of the EDLCs and the fuel consumption. Using this proposed control methods, excessive charging of EDLCs can be avoided. The results of this study are expected to expedite the development of energy-saving railway vehicles for the non-electrified lines. Finally, the results of this study increase the possibility of developing hybrid powered railway vehicles.
Through experiments, this paper newly validates analytical correlation characteristics between rotor and major-axis phases of high-frequency current trajectory caused by injection of the generalized high-frequency ellipse voltage.
The ordinary experimental equipment has a long stroke or a large cylindrical rotating secondary side in order to measure the drive characteristics of Linear Induction Motor (LIM). In this paper, we propose the measurement method of the drive characteristics of LIM with the experimental equipment implemented a disc-shaped secondary side. This method makes the experimental equipment smaller in size. It has been shown that the drive characteristics of LIM can be successfully measured.
This paper presents a new general analysis about salient-pole characteristics of permanent-magnet synchronous motors (PMSMs) that have the magnetic cross-coupling. In the actual case with magnetic cross-coupling, salient-pole and N-pole phases are not the same, and there is phase error between them. The unique general solution of the phase error is presented.
This paper proposes a new quadrature signal generator and an estimation method for fundamental components of single phase signals with the generator. In the proposed method, the quadrature signal is generated with the difference of input signal and the first order LPF output. The effectiveness of the estimation method for the fundamental components with the quadrature signal is confirmed by the simulation results.