In position sensorless positioning servo systems, the parameter mismatch between interior permanent magnet synchronous motors (IPMSMs) and a position controller and/or a position estimator due to thermal variation and aged deterioration has not been sufficiently investigated. This paper proposes a convolutional integration-based second-order differential calculation to identify the parameters of IPMSMs for a high-performance positioning servo system in an adaptive scheme. In addition, we propose a high-frequency voltage injection strategy considering the trade-off between acoustic noise suppression and estimation performance. The effectiveness of the proposed second-order differential calculation calculation method, and the high-frequency voltage injection for the acoustic noise suppression is verified experimentally.
This paper presents an analysis of the maximum torque minimum peak phase current of the dual winding interior permanent magnet motor. Reducing the current contributes to small motor size. The peak phase current to generate the torque is reduced by the cancelation of the torque ripple generated by the two windings. The high harmonic current that does not generate torque ripple in the dual winding motor is analyzed. With the high harmonic current, the minimum peak phase current to generate a predetermined torque is calculated. The experiments were conducted to confirm the reduction of the peak phase current without increasing the torque ripple.
This paper presents a method for improving the position estimation accuracy for magnetic saliency based sensorless control. Conventional magnetic saliency based sensorless position estimation methods are based on the voltage equation of Interior Permanent Magnet Synchronous Motor without incorporation of the mutual inductances between the d-axis and q-axis of rotating reference frame synchronized with rotor. The mutual inductances are caused by magnetic saturation due to load current and high-frequency injection signal for position detection. Furthermore, the mutual inductances contain the harmonic components due to the motor structure. Consequently, the position estimation error is caused by the neglected mutual inductances. It is difficult to determine the actual value of mutual inductance, particularly the harmonic components that vary depending on the rotor position. Therefore, in this paper, a method for improvement of the position estimation accuracy by considering the cross-coupling factor without determining the mutual inductances is proposed. The experimental results demonstrate the validity of the proposed method.
This study evaluated the performance of the Quasi-Zenith Satellite System (QZSS) in Japan at an early stage for its future sustainable operation. After the four satellites of QZSS Michibiki started their official operation, the fixed-position and moving vehicles simultaneously received centimeter-class positioning augmentation signals, L6D-CLAS (Centimeter-Level Augmentation Service), and L6E-MADOCA (Multi-GNSS Advanced Demonstration tool for Orbit and Clock Analysis) from Michibiki. This is the first attempts the results of real-time.
To suppress the residual vibration of the resonance frequency of a three-inertia system, this paper proposes a current control system that has a resonance damping structure focusing on the vibration modes of the three-inertia system. Because the conventional position/velocity control system based on the two-inertia model focuses only on the primary resonance frequency, its residual vibration is induced by using the conventional control system based on a two-inertia model as against the three-inertia system. The conventional current control system does not include a resonance damping structure. The proposed current control system damps the secondary resonance frequency of the three-inertia system, whereas the ordinary position/velocity control system suppresses the primary resonance frequency of the three-inertia system. The effectiveness of the position/velocity control system using the proposed current control is confirmed through experiments.
The global navigation satellite system (GNSS) is a satellite positioning system. However, when the signal is shielded by reinforced concrete or metal, it is difficult to be received indoors. This study introduces an indoor location estimation scheme based on bluetooth low energy (BLE) for pedestrian navigation that can save power and reduce the installation density. We investigated indoor positioning methods with the use of the received signal strength indicator (RSSI) in association with two BLE transmitters as the main axis. The error of the single RSSI ranging is more than several tens of meters, and is insufficient for use for pedestrian navigation. However, this error is reduced to a few meters when the proposed simple proportional correction calculation is performed for the estimated distance. The target accuracy required for pedestrian navigation for healthy people is approximately 10m. This is equivalent to the accuracy of outdoor satellite positioning. For example, given that the size of the Shibuya underground shopping street is approximately 4,676m2, twenty BLE beacons can cover the entire area. If this technology is established, indoor positioning can become possible within a wider range with a lower cost and lower labor effort compared with the current state-of-the-art.
Measurement of airborne radiation must be performed before and after decontamination work to confirm whether decontamination has actually been performed. Conventional measurement procedures require enormous amounts of work. Without using a specific mark, it is difficult to find the same measurement location before and after the decontamination work. To overcome these problems, we developed an airborne radiation mapping system that can perform measurements precisely and quickly. The system enables the simultaneous measurement of airborne radiation at multiple heights by utilizing multiple measurement units. In addition, we developed a new navigation system to reduce workload. The airborne radiation mapping system facilitated quick measurement and easy movement.
This paper presents a method for the mathematical-model-based simulation of automotive alternators. In the proposed method, a rectifier and motor are expressed by an electrical circuit constant that includes resistance and inductance. Moreover, a power correction factor is introduced for considering the operation of the rectifier. Owing to this, the calculation accuracy can be improved over that of a conventional mathematical simulation method. To validate the effectiveness, calculation results are compared with the experimental results.
This paper presents the design of a hybrid state observer that estimates the sway angle in trolley systems with a pendulum, such as overhead cranes. In the system, sway angle signals detected by angular sensors are generally used for designing the anti-sway control of the pendulum or observing the pendulum state. By contrast, in this study, a linear state observer without sensors is applied to estimate the sway angle of the pendulum. The use of a standard asymptotic state observer leads to estimation error due to the system's nonlinearities and parametric errors. This paper proposes using a hybrid state observer design that combines discrete event sensing with a linear state observer. In the hybrid state observer, the estimation performance is improved by correcting the state of the system based on the discrete sway angle and angular velocity using discrete sensing. In addition, the parametric error of the pendulum length of the system is identified using the same hybrid setting. The effectiveness of the hybrid state observer and the parametric adaptation of the pendulum length are verified by conducting experiments using a downscaled prototype of a trolley system with a pendulum.
This paper presents a new control system for permanent magnet synchronous motors composed of a 2-degree-of-freedom deadbeat control with a disturbance compensation method using a field-programmable gate array (FPGA). The purpose is to achieve quick response and improve the tracking accuracy of motor current and the robustness against parameter variations. The proposed control system using a FPGA based the hardware controller with simple implementation can compute all calculation process within the dead time of an inverter, realizing ideal real time feedback control without sample delay. The performance of the proposed control strategy was verified in comparison with the conventional deadbeat control method through simulations and experimental results.
The calculation of core loss of power electronics converters requires a large number of core loss data, including the excitation frequency, flux density ripple, and DC magnetic field bias characteristic under rectangular voltage excitation. However, in the case of the conventional method (that employs a B-H analyzer with a chopper circuit), a very long time is required to collect this core loss base data, because circuit parameter tuning is needed for each measurement point. Therefore, we propose a high-speed core loss base data collection method for core loss calculation under power electronics converter excitation. The core loss base data collection time was substantially reduced upon usage of a pulse width modulated (PWM) inverter and a neural network because various core loss characteristics were expressed upon excitation of the PWM inverter, and these core losses were learned by the neural network. The core loss base data, as measured via the proposed and conventional methods, were compared to validate the measurement accuracy of the proposed method, and the difference was found to be lesser than 12%. Thus, the proposed method achieves high-speed core loss base data collection.
Partial shading on a photovoltaic (PV) panel consisting of multiple substrings is known to trigger a significant reduction in energy yield and the occurrence of multiple maximum power points (MPPs), including one global and multiple local MPPs. Uneven irradiance on curved PV panels, such as flexible panels and solar roofs of electric vehicles, also causes characteristic mismatch, triggering the same issues. Although various types of differential power processing (DPP) converters have been proposed to preclude the characteristic mismatch issues, the DPP converter is separately required in addition to an existing boost converter for panel control, resulting in increased system complexity, cost, and volume. This study proposes a novel integrated converter that realizes system simplification and circuit miniaturization by integrating a PWM boost and a DPP converter into a single unit. Laboratory and field tests were performed emulating partial shading and characteristic mismatch conditions. The proposed converter eliminated local MPPs and increased maximum power while boosting the panel voltage, demonstrating the efficacy of the proposed integrated converter.
This paper presents a bidirectional converter with multi-stage FETs featuring voltage balance control function using variable capacitors. The proposed converter is constructed using low-voltage Si-FETs in a series connection, and it improves the voltage balance between the drain-source voltages of the series connected FETs in the OFF period. Using the converter figure of merit (FOM), which can estimate the converter losses from the specifications of the FETs, the effectiveness of the proposed converter is compared to that of a converter using SiC-FETs. The factors of the voltage unbalance are analytically clarified using the equivalent circuit. The principle of voltage balance control function using the variable capacitor is discussed. The experimental results show that the proposed converter can achieve a maximum power conversion efficiency of 99.2%.
We have been studying the application of amorphous metal with low loss to axial gap motors. However, since radial gap motors are the most widly used motors, a motor structure that can apply amorphous metal to a radial gap motor was studied. In our previous study, we reported the study on SPM motors with concentrated winding. In this study, we evaluated the effect of high efficiency on the distributed winding IPM motor with high magnetic flux density inside the iron core. As a result, it was confirmed that the efficiency can be improved by reducing the iron core loss.
This paper presents a bidirectional non-isolated dc-dc converter based on three-level flying-capacitor converters intended to be applied to electric railway systems. It consists of several main converters with four power devices per converter, multiple auxiliary converters each of which is formed by cascaded chopper cells, and inductors for current control. The dc-dc converter can achieve zero-current switching (ZCS) for all the power devices in the main converters, not only under steady-state conditions but also under transient-state conditions including sudden changes in the supply voltage. This paper presents a current control method based on dq0 transformation and a voltage control method for the floating dc capacitors used in the auxiliary converters. The validity of the control methods proposed in this paper is verified through experiments using a 200-V, 2-kW downscaled model.