This paper proposes a position sensorless drive system combined with on-line parameter identification for an interior permanent magnet synchronous motor. The accuracy of the position estimation can be improved by the proposed system, in which the motor parameters used for the position estimation are identified according to the operating conditions. First, the influence of the parameter error on the estimation position error is examined from the simulation and experimental results. Next, the characteristics of the sensorless drive system and the performance of parameter identification are shown. The experimental results show that the proposed system can achieve more accurate position estimation than the drive system without the parameter identification for all operating conditions.
We developed a 6.6-kV 1-MVA transformerless converter making use of a snubberless insulated gate bipolar transistor (IGBT) 8-series connection using an Active-Gate-Control. The Active-Gate-Control can balance the collector voltage of IGBTs connected in series enabling the IGBT series connection. It allows the converter to output a high enough AC voltage to directly connect to 6.6-kV distribution lines. Therefore, the converter does not need a step-up and step-down transformer, and is extremely small and compact.
This paper compares the capabilities and costs of Advanced 14v, 42v and High Voltage (144-300V) systems for hybrid and fuel cell vehicle applications against the environmental benefits obtained in different operating conditions (e.g. “typical car driving”, delivery van usage, etc.). To support this the electrical architectures for a number of vehicles optimised for different usages will be presented together with their measured environmental gains (fuel consumption, CO2, etc.). It will be shown that usage patterns (operating conditions) significantly impact the cost/performance benefits obtained. Suitable electrical architectures showing good cost/performance benefits for particular usage patterns are described.
This paper proposes a new method of compensating harmonic currents for wind power generation systems with the soft starter using a hybrid active filter. The hybrid active filter consists of single-tuned LC and small-rated active filters. The single-tuned LC filter absorbs the harmonic current while behaving as a phase-leading capacitor for the fundamental component. The small-rated active filter improves the compensation characteristics of the passive filter under the soft start of the constant-speed wind turbine. The required rating of the active filter can be reduced because the active filter does not supply the fundamental reactive current. The basic principle of the proposed compensation method is discussed, and then confirmed by digital computer simulation using PSCAD/EMTDC. Simulation results demonstrate that the waveform of the source current becomes sinusoidal under the soft start. The required rating of the active filter is about 8.5% of the induction generator rating. A new calculation method of THD with the detrending algorithm is proposed for the transient state. The THD of the source current is about 7.3% using the hybrid active filter.
Matrix converters have no boost capabilities. Their output voltage amplitude is therefore reduced compared to back-to-back inverter topologies. Moreover, they are sensitive to grid voltage fluctuations and disturbances and the voltage transfer ratio is further reduced under such grid perturbations. The present paper analyses the behaviour and limits of the two-stage matrix converters. It proposes and investigates three alternative topologies that modify the DC-link voltage of the two-stage matrix converter, by the means of additional circuitry, in order to increase the voltage transfer ratio above unity and to obtain immunity to grid disturbances. A high-performance control of the grid current is required to obtain a power factor close to unity. An effective control method is proposed for each converter. Feed-forward model based controllers allow obtaining good performances. Finally, the performances of the topologies are analysed and compared.
In this paper two bi-directional DC-DC converters for a 1MW next-generation BTB system of a distribution system, as it is applied in Japan, are presented and compared with respect to design, efficiency and power density. One DC-DC converter applies commercially available Si-devices and the other one high voltage SiC switch, which consists of a SiC JFET cascode (MOSFET+1 JFET) in series with five SiC JFETs. In the comparison also the high frequency, high voltage transformer, which ensures galvanic isolation and which is a core element of the DC-DC converter, is examined in detail by analytic calculations and FEM simulations. For validating the analytical considerations a 20kW SiC DC-DC converter has been designed in detail. Measurement results for the switching and conduction losses have been acquired from the SiC and also for a Si system for calculating the losses of the scaled 1MW system.
Equivalent circuit constants of permanent magnet synchronous motors are needed in the calculation of operation characteristics, construction of a control system, etc. These constants can be computed from the data on structural form and materials. However, measurements are necessary to obtain highly precise values. Measurement methods of the d- and q-axis inductances can be roughly divided into rotational and standstill methods. The standstill methods have the advantage that they are easy to carry out. However, it is difficult to consider magnetic saturation and distortion of the change in armature winding inductance. The accuracy of the standstill method can be improved if these effects can be readily taken into account. This paper describes a standstill method for measuring accurate d- and q-axis synchronous inductances of permanent magnet synchronous motors. By utilizing the fact that the EMF interference terms in the motor voltage equation considering the distortion of the inductance change are equal to zero when the rotor is in a specific position, the proposed method determines the inductances considering both magnetic saturation and inductance distortion effects from simple off-line standstill testing. In addition, this method is capable of taking cross-magnetic saturation into account when used with the necessary testing equipment. The proposed method is implemented on a 0.4kW interior permanent magnet synchronous motor with concentrated stator winding. The validity of the proposed method is demonstrated by comparing measured and calculated results of no-load and on-load characteristics.
The equivalent circuit, the efficiency and the important characteristics of moving pick-up type contactless power transfer systems are described. If primary series capacitor and the secondary parallel capacitors are chosen correctly and the winding resistances are ignored, the equivalent circuit of the transformer with these capacitors becomes the same as an ideal transformer at the resonant frequency. This simple approximation helps to understand the phenomena with load changes. As the circuit analysis becomes simple, the approximate value of power transfer efficiency can be derived. This paper describes the determination of the capacitor values, the derivation of the equivalent circuit and the efficiency, and the test results.
High-frequency leakage current that may cause serious conducted EMI problems flows through an inverter system. The paths of the leakage current are stray capacitors that are formed inside of motors, cables and IGBT modules. This paper proposes a new IGBT module that realizes low conducted emission noise by flipping the IGBT chip of lower-voltage-side to decrease its stray capacitance. The leakage current flowing through the low-noise IGBT module becomes small, since the stray capacitor is a main path of the current. Through an experiment, it is clarified that the conducted emission level is reduced by 13dB at a maximum when the low-noise IGBT module is applied to a resonant-type inverter.
Recently, renewable resources supplies, such as fuel cells, photovoltaic cells, wind power and engine generators, for distributed power system have been studied intensely. Conventional compensators with switching devices are constructed based on a voltage source inverter using six arms. Therefore, conventional power quality compensators require a large electrolytic capacitor in the dc link part of the equipment. The use of a large capacitor hinders downsizing efforts and the lowering of equipment costs. Direct converters, which do not have a large electrolytic capacitor and an initial charge circuit, can be used to realize downsizing and lowering of equipment costs, when compared with conventional converters. This paper proposes one of new applications of a matrix converter to a PM generator for power quality compensation, such as reactive power compensation, harmonic current and power interruption. The novel point of this work is that the matrix converter provides reactive power with harmonic current. Simulated and experimental results confirm that the matrix converter can maintain high performance as same as a conventional active filter and an uninterruptible power supply (UPS).
In these years, plant control systems are highly automated and applied to many industries. The control performances change with the passage of time, because of the deterioration of plant facilities. This is why human experts tune the control system to improve the total plant performances. In this study, PID control system for the oil refining chemical plant process is treated. In oil refining, there are thousands of the control loops in the plant to keep the product quality at the desired value and to secure the safety of the plant operation. According to the ambiguity of the interference between control loops, it is difficult to estimate the plant dynamical model accurately. Using neuro emulator and recurrent neural networks model (RNN model) for emulation and tuning parameters, PID gain tuning system of chemical plant controller is constructed. Through numerical experiments using actual plant data, effect of the proposed method was ascertained.
In order to suppress slip/skid phenomenon, we have already proposed anti-slip/skid re-adhesion control system based on disturbance observer, and we have confirmed that this system drives the train with high adhesion force utilization ratio. However, this system does not consider the vibration phenomenon of actual bogie dynamics of electric commuter train, tangential force estimation is affected by bogie vibration. Hence, the drive control system cannot determine the appropriate motor torque reference, and sometimes reduces the adhesion force utilization ratio. This paper proposes a new anti-slip/skid re-adhesion control system based on the disturbance observer considering the first resonant frequency of the bogie system. In order to confirm the validity of the performance of the proposed anti-slip/skid re-adhesion control system, this paper confirms the validity of the proposed system by using the numerical simulation. This paper shows the numerical simulation results simulated using 4M1C motor car model which has a sensor-less vector control system. As the results, the proposed disturbance observer is effective for the vibration suppression of estimated tangential force. The numerical simulation results point out that the proposed adhesion control method has the fine performance.
A modular multilevel converter (MMC) is one of the next-generation multilevel PWM converters intended for high- or medium-voltage power conversion without transformers. The MMC consists of cascade connection of multiple bidirectional PWM chopper-cells, thus requiring voltage-balancing control of their chopper-cells. However, no paper or article has been presented or published on the voltage-balancing control with theoretical and experimental verifications. This paper deals with two types of modular multilevel PWM converters with focus on their circuit configurations and voltage-balancing control. Combination of averaging and balancing controls enables the MMCs to achieve voltage balancing without any external circuit. The viability of the MMCs as well as the effectiveness of the PWM control method is confirmed by simulation and experiment.
Medical devices have been obliged to satisfy electromagnetic compatibility by revision of the pharmaceutical affairs law. However, even if the medical devices satisfy the electromagnetic compatibility based on the law, it is not necessarily safe. Sometimes, malfunctions of cardiac pacemaker are caused by the magnetic field leaked from an induction heating cooker. In this paper, a new method of electromagnetic susceptability (EMS) evaluation is proposed, and a loop coil for the magnetic field immunity test in the frequency range from 10kHz to 3MHz is designed and developed. As a result, the loop coil made on an experimental basis generated uniform magnetic field with a fluctuation within 3.3dB in the loop coil pane and 5.6dB along the coil axis.