This paper describes a new sensorless control technique for switched reluctance motors. The proposed system injects voltage pulses into the two unexcited windings and observes their currents. Timing signals for commutating the inverter are generated by comparing these currents. Almost no predetermined parameters are required for system setup. In the experiments, the proposed drive system is verified at 1000 and 3000min-1 under load. The system achieves acceptable commutation timing accuracy and provides robustness to DC-link voltage ripple and to output torque.
This paper proposes fade torque control to reduce unexpected steering torque and self-steer for a driver switching between the two steering modes (manual steering and automated steering). This fade torque control provides the driver stable steering torque, and it also allows him/her to operate the steering wheel safety. We demonstrate the effectiveness of the proposed fade control through experimental verification.
A multi-phase DC-DC converter is effective for miniaturization and achieving high power density in a switching power supply. However, its mathematical modeling becomes complex as the phase number of the circuit increases. This study proposes a new modeling method to derive a reduced order method in a simple manner. The frequency characteristics of the reduced order model are fit to those of the original mathematical model of the multi-phase DC-DC converter. Therefore, the efficacy of the proposed method is validated.
An X-ray computed tomography (CT) apparatus is required for the inspection of semiconductor packages to detect fine voids with high accuracy. However, obtaining high-quality CT images stably is difficult because of object misalignment. In this paper, we propose a method for improving the X-ray CT image quality by estimating the mechanical misalignment of each projection image. The estimation is conducted by using an iterative method based on the characteristic features obtained from the reconstructed image. In experiments, we verified the effectiveness of proposed method by using projection images with simulated misalignments added. The results indicated that the proposed method may be useful for improving the quality of CT imaging.
In this paper, a control method for reducing the switching ripple currents flowing to a DC-link capacitor in a two-stage single-phase charger is presented. The switching sequences of both converter circuits are addressed by applying triangular and saw-tooth carrier waveforms in order to reduce the switching ripple current of the DC capacitor. Moreover, a sampling method of the current that is suitable for application in the control procedure is proposed. The proposed method varies the sampling frequency and points according to the input and output voltage conditions. The reduction effect of the switching ripple current is confirmed by analysis and the results of an experiment in which a DC-DC converter with power factor correction was used under the conditions of a source voltage 100V and an output power 1 kW.
This paper describes the inverter drive characteristics of a 2.4 MW permanent magnet generator (PMG) for a diesel electric propulsion system. We demonstrated the relations between the PWM (Pulse-Width Modulation) pulse patterns and temperature rise in a permanent magnet in a PMG. Additionally, we demonstrated that inverter failure has a significant impact on the current and torque in a PMG.
This paper proposes the harmonic current control of a permanent magnet synchronous machine using complex vector form PI controllers. The complex vector form PI controllers are designed based on voltage equations written in complex vector notation in multiple reference frames that synchronize with the harmonic current. Thus, a decoupling control in each reference frame can be achieved that has been difficult to realize in the past. The proposed method improves the transient response of the harmonic current control by realizing the decoupling control in each reference frame. Moreover, the proposed harmonic current control method can be designed and implemented easily because the PI gain design method for all harmonic orders is the traditional pole-zero cancellation method, which is well known. This paper presents the transient response and parameter sensitivity of the proposed harmonic current control that were obtained from the results of the simulation and experiment conducted, which reveal the effectiveness of the proposed method.
In this study, a static synchronous compensator (STATCOM) with a delta-connected modular multilevel converter (MMC) was considered. Because a low harmonic distortion is realized with MMC topology, the switching frequency can be reduced to one-pulse, and an extremely low switching loss can be achieved. However, details on one-pulse control of an MMC-STATCOM have not been clarified. This paper describes control strategies for one-pulse control of a delta-connected MMC-STATCOM and proposes an individual balance control to balance all capacitor voltages with a low modulation index or redundant configuration. Experimental results verified the proposed balance control and one-pulse operation under stable and system fault conditions.
The weld-bonding method uses adhesion and spot welding it has the advantages of high fatigue resistance, high rigidity, no need of a jig for adhesion, and so on. However, the conventional adhesive is an epoxy resin, which is cured by a chemical reaction. Therefore, the adhesive needs a long curing time. In an automobile assembly factory, the adhesive is cured by drying during the body painting process. The standby period before the drying process influences the quality of the adhesive. To solve this problem, we propose a new method that uses an epoxy resin with a thermal agent added and induction heating (IH) for quick curing. We obtained the fundamental data of IH coil heating steels for practical application of the new method. Based on the experimental and analytical results, suitable conditions regarding the frequency and IH coil position for automobile steel models were selected. Finally, we determined a semi-cured heating temperature for the adhesive of more than 120°C and IH coil movement of 10cm/s for practical application.
Partial shading on a photovoltaic (PV) panel comprising of multiple substrings connected in series leads to major issues, such as decreased power generation and occurrence of multiple power point maxima. Various PV equalizers have been proposed to preclude partial shading issues. However, system complexity increases because of the addition of PV equalizers, and circuits are prone to complexity because each PV equalizer contains switches. This study proposes a single-switch PWM converter integrating a PV equalizer using a series-resonant voltage multiplier (SRVM) for PV panels under partial shading. A PWM converter and PV equalizer can be integrated into a single unit, which decreases the switch count, achieving system- and circuit-level simplifications. Detailed operation analysis was performed for the SRVM, using which a dc equivalent circuit was mathematically derived. Experimental tests using a prototype for three substrings connected in series were performed with solar array simulators. The integrated converter successfully precluded the occurrence of multiple power point maxima and significantly improved the extractable maximum power as compared to that without equalization, demonstrating its efficacy.
Single-phase diode rectifiers offer simple topology, low high-frequency noise, high reliability, and high environmental durability. However, diode rectifiers produce undesirable lower order harmonics in the input current. To overcome the problem, the authors present a single-phase power factor correction diode rectifier without active switching devices. To illustrate the validity of the rectifier, experimental results obtained from a 1.5kW, 200V system are shown.