The short cruising distance per charge is a major technical challenge associated with electric vehicles (EVs), compared to hybrid and conventional vehicles with internal combustion engines. Dynamic wireless power transfer (DWPT) is a feasible solution to increase the cruising distance of EVs equipped with small capacity batteries. DWPT eliminates the need to use a large capacity batteries in an EV. This makes EVs lighter and thus reduces the energy required for cruising. Notably, the manufacture of large capacity batteries cause large quantity of greenhouse gas (GHG) emissions. Therefore, DWPT can contribute to reducing GHG emissions. This study estimates the GHG emissions of passenger electric vehicles with the DWPT system, including transmitter coils and inverters, and compares their emissions with those of passenger EV equipped with large capacity batteries. The number of DWPT transmitter coils was estimated by simulation using actual driving data on local roads and expressway gradient data. The comparison results show that DWPT system can reduce 34.1% of GHG emission compared to EV with large capacity batteries.

The flux-modulating hybrid-field consequent pole motor (FHCM) is a new type of double-stator axial-gap motor in which the field poles are composed of consequent poles and ring-shaped DC field windings. This paper proposes a field flux model to investigate the torque enhancement mechanism of the FHCM. The electromagnetic performance of the FHCM is also compared with that of three existing double-stator axial-gap flux modulating motors whose field poles are composed of permanent magnets, a field winding, or both of them, in addition to a standard radial-gap interior permanent magnet motor. Furthermore, experimental results are provided for a prototype machine to justify the theoretical and three-dimensional finite element analysis approaches. The results show that the FHCM can achieve both the highest efficiency and torque among the compared motors by adjusting the field current.

Green bus stations use solar energy to operate the station, a notable innovation in the public transportation sector. The station is capable of providing its own energy source due to the solar power and energy storage systems. The solar energy source is exploited by an innovative maximum power point tracking (MPPT) method that can optimally exploit the available solar energy source. The improved MPPT method exhibits a fast convergence time in all solar intensity conditions. The fast convergence time ranges from 0.54 – 0.64 seconds. The bus station is integrated with other amenities – such as fans, smart lighting systems or smartphone chargers – to create comfort for passengers. A station model was built to encourage people to use public transportation, contributing to the goal of global environmental protection.

Electrical machines are at the center of future aircraft propulsion architectures, and their improvement is key in increasing the market uptake of cleaner transport. This paper investigates recent/ongoing improvements within the constituent technology bricks, including the magnetic materials, insulation, thermal management, coil winding, and wire technologies, and estimates the performance entitlements from each considering an 800 kW 1800 rpm direct drive aircraft propulsion motor. The combination of advanced technology bricks is then discussed for two aerospace machine case studies involving a 4 MW, 15 krpm, 17.3 kW/kg generator and a 300 kW, 6500 rpm, 15-25 kW/kg motor.

This paper proposes a relationship between the M- and T-axis currents for the maximum torque per ampere (MTPA) control of permanent magnet synchronous motors (PMSMs). This paper focuses on a rotating reference frame, which is synchronized with the stator flux-linkage vector. The validity of the proposed relationship is confirmed by using finite element analysis (FEA) and measured values of the tested motor. The control characteristics of the M- and T-axis current control system are also evaluated.

This article presents an input/output passive common-mode noise canceller to suppress common-mode (CM) currents on the input and output sides of a three-phase pulse-width-modulation inverter-fed motor drive system. Unlike conventional configurations where common-mode transformers (CMTs) are concentrated only on the input or output side of the inverter, the proposed method distributes CMTs on both sides. The proposed configuration enables the CM current flowing through the heat sink ground wire of the inverter to be suppressed effectively. Consequently, the proposed method improves the CM current attenuation characteristics of conventional methods. Experimental results demonstrate the effectiveness of the proposed method.

The operation of SiC MOSFETs with high 𝑑𝑖/𝑑𝑡 and 𝑑𝑣/𝑑𝑡, coupled with high parasitic oscillation frequency due to low device parasitic capacitances, can increase electromagnetic interference (EMI) noise in the high-frequency region. For the prediction of conducted EMI emissions, analytical models are preferred. However, they require accurate circuit switching transients and noise-propagation path parasitics modeling. To analytically model device switching transients, circuit parasitics values are required. Despite their importance, complete parasitic models of power modules are rarely provided by manufacturers. In this study, a wiring parasitic inductance characterization method for a full-bridge power module, based on 4-port S-parameter measurements, is proposed. A numerical model of power module wiring parasitics is presented and experimental S-parameter data is used to calculate parasitic inductances. These calculated parasitics values are validated by comparing them with FEM simulation results.

The greater the number of degrees of freedom a manipulator possesses, the higher the gravitational torque required, which can result in excessive energy consumption. One of the solutions to this problem is gravity compensation, which mechanically suppresses the gravitational force and torque without external energy supply. Although numerous studies on gravity compensation have been conducted over the past decades, certain challenges persist, such as increased manipulator weight and restricted range of motion due to additional components required for gravity compensation. Therefore, this study proposed a tendon-driven mechanism of gravity compensation. In this method, springs are employed for gravity compensation, and these elements can be mounted away from manipulators. Moreover, this mechanism has a spherical joint actuated by parallel tendon mechanism, which enables manipulators to realize threed-imensional motion. The novelty of the proposed approach lies in the absence of additional components within the manipulator body. By utilizing a tendon-driven and parallel-tendon mechanism, the proposed design overcomes the limitations of conventional gravity compensation methods. In this study, we created a two-link manipulator according to this proposed mechanism and confirmed the effectiveness of the proposed gravity compensation mechanism.

Robots should be able to interact more actively with the general public to operate close to them. However, human communication is sometimes performed at high speed and involves collisions, which poses a safety problem when humans and robots interact. To perform these actions safely, the energy involved in a collision should be reduced, and it is useful to reduce the inertia of the robot. Additionally, it is crucial that the back-drivability is sufficiently large to follow external forces. We used an in-link actuator to reduce the inertia of a robot with direct-drive joints. In-link actuators, with a drive mechanism incorporated into the links, enable the creation of a low-inertia robot with joints that can be driven quickly even with a small torque. Experiments were conducted to confirm the effectiveness of the in-link actuator in contact motion. By measuring the force during a collision and moving while holding down a fragile object, we demonstrate that the use of in-link actuators enables a higher level of interaction without damaging the outside object compared to the use of motors.

This study proposes a power compensation method for a single-phase ac power supplied dual inverter without a large electrolytic capacitor. In the electrolytic capacitor-less dual inverter, a primary inverter outputs a pulsating power to improve the grid power factor without a power factor correction circuit. However, the low-voltage utilization owing to the power pulsation, which reduces the motor-operating region and system efficiency, is a primary limitation of the system. The proposed method generates voltage reference values of two inverter based on the instantaneous motor power. This facilitates dealing with power flow in the electrolytic capacitor-less dual inverter. In this study, the primary and secondary inverter only output active and reactive power, respectively, using the proposed method. Consequently, a reactive power pulsation, which is unnecessary for the power factor correction, is eliminated, and the voltage utilization of the primary inverter is improved. The simulation and experimental results show that the proposed method increases the output torque and system efficiency by up to 72 % and 11.8 pt., respectively, compared with the conventional control method.

This letter presents a condition-monitoring method of a DC-link capacitor in a vehicle-to-everything (V2X) bidirectional electric vehicle (EV) charger. EVs have gained considerable attention because of portable energy sourses, thereby resulting in the development of V2X bidirectional EV chargers. Surveys of reliability in power electronics indicare that 20-30% of converter failures are attributed to capacitors. The proposed method enables condition monitoring of DC-link capacitors for the charge or discharge output changes.

This paper presents a ripple-current compensation method for a dual active bridge (DAB) converter with a matching transformerless series DC active filter (DCAF) in a DC distribution feeder. The input and output currents of the DAB converter contain large ripples, which can negatively affect connected devices such as batteries and solar cells. A matching transformerless DCAF is connected in series between the DC source and DAB converter. The DCAF compensates for the ripple voltage and current of the DAB converter. Experimental results indicate that the proposed method lowers the ripple voltage and current of the DAB converter to 44.9% and 65.0%, respectively.

In physical human-robot interactions, a collaborative robot physically interacts with a human to perform tasks in industrial settings. For safe interaction during collaborative work, analyzing the stability is beneficial. The previous study has analyzed the stability with the bias of a human's force perception and reproduction and interaction models with a reproductive controller, where a robot reproduces the force applied by a human. However, the effect of a force controller was not investigated. Thus, this study investigated different effects of a model-based controller, where a robot produces the force based on a human's input-output characteristic of force reproduction, and the reproductive controller for discrete-event physical human-robot interaction. We analyzed the stability and convergence on interactions using the reproductive and model-based controllers. Then, we found that the interactive force using the model-based controller significantly converged toward a human's implicit equilibrium point caused by the bias, and found faster convergence of the model-based controller than the reproductive controller.

This paper addresses the hierarchically decentralized disturbance observer-based controller (HD-DOBC) for large-scale dynamical systems. Particularly, this paper focuses on a control configuration that employs lower-to-upper aggregation in the physical-space, and upper-to-lower distribution in the cyber-space. To simplify the design process, a role-sharing mechanism between global and local controllers is introduced through a “global/local shared model set,” which is employed at both layers. This approach establishes a fairly general framework and derives a procedure that enabling global and local controllers to be designed using standard robust control techniques. Importantly, the complexity of system design remains independent of the number of local agents. The proposed approach was validated via a dual-propeller testbench, where the global objective was yaw angle control, and the local objective was propeller speed control. Leveraging the shared model set, the global/local trade-off was experimentally examined. Test results demonstrate that, even under strong wind conditions, the HD-DOBC reduces the attitude tracking error by 33% compared to a conventional control system that applies DOB only in the upper-layer.

This paper proposes a cross–coupled two–degree–of–freedom (2–DOF) tubular surface permanent magnet synchronous motor (SPMSM). In the proposed motor, the stator part consists of two bobbins with helical three–phase windings. The mover part is a shaft on which the segment permanent magnets are pasted in the checkered pattern. As a result, two orthogonal Lorentz forces in helical directions can be generated. The thrust force can be controlled as a sum and the rotational torque can be controlled as difference. This implies that the proposed motor has modal decomposition function of common mode and differential mode as a distinctive feature of its structure. This paper establishes the mathematical modeling of the proposed motor to represent the motion principle. The finite element analysis (FEA) results show the adequacy of the established theory. Moreover, the utility of the proposed motor is verified through experimental results obtained from prototype.

This paper introduces the bidirectional functionality of a flyback converter achieved using a soft-switching technique. The proposed method can harness electrical energy more efficiently than conventional circuits, which are restricted to unidirectional power supplies. We focused on the flyback converter circuit, which uniquely integrates soft-switching and bidirectional operation, thus facilitating superior power conversion. Specifically, we assessed the power conversion efficiency of the assembled circuit during the boost and buck operations at a switching frequency of 1 MHz. The empirical results demonstrated that the power conversion efficiency was 83.2% in boost operation and 81.9% in buck operation. Furthermore, we successfully implemented bidirectional operation by simply adjusting the duty cycle and phase of the switching devices.

Model predictive current control (MPCC) is a fast and accurate current control method for interior permanent magnet synchronous motors (IPMSMs), which controls the current on the basis of current values predicted using a mathematical model of the IPMSM. MPCC requires accurate motor parameters, and a parameter estimation using a current ripple caused by MPCC has been proposed. As this ripple causes acoustic noise and vibration, a voltage smoother has recently been proposed to suppress the ripple. High-performance current control necessitates an appropriate combination of both parameter estimation and voltage smoothing; however, combining them is difficult. Suppression of the current ripple makes parameter estimation difficult. Therefore, a novel estimation method based on dynamic regressor extension and mixing (DREM) is proposed for realizing high-performance current control in MPCC-controlled IPMSM. Experimental results demonstrate the validity of the proposed approach.

This paper proposes a novel optimal control method for operating each powertrain component of a series hybrid electric vehicle (SHEV) while reducing the total energy loss during a trip with a given speed profile. The proposed method formulates the SHEV energy management problem (EMS) as a novel optimization problem. This study has novel aspects: 1) The proposed method simultaneously optimizes the ignition on/off timing and operating points of powertrain components without involving any binary variable. 2) Function 1) is realized by defining the reference values and actual values of ignition on/off timing, engine output torque, and inverter conversion rate as continuous variables separately, setting the reference values as optimization variables and including a designed function in the performance function to avoid engine ignition when the engine speed is lower than the idling speed. 3) The entire brake-specific fuel consumption (BSFC) map is modeled for optimization instead of restricting the engine operating point to the optimal line of BSFC. 4) A rule-based control method is established according to the control method used on commercial SHEVs to validate the effectiveness of the proposed method. 5) The control results under four initial conditions are compared to validate the rationality and effectiveness of the rule-based and proposed methods in reducing the total energy loss. Both methods can efficiently control the powertrain components. However, in all four case studies with different initial state of charge values, the proposed method and the rule-based method generate different ignition timing and operating points for the components in the powertrain. The proposed method reduces the total energy loss and fuel consumption by over 19.41% and 13.75%, respectively. Moreover, the proposed method eliminates the chattering of the engine ignition on/off switch.

Automotive motors are necessary to reduce vibrations and improve reliability. Double-star permanent-magnet synchronous motors (PMSMs) improved reliability however, they generate a radial force, causing vibrations similar to those of conventional three-phase PMSMs. This study introduces a radial force suppression method using a double-star PMSM which increases the degrees of freedom of synchronous frames from two to four, and two redundant degrees of freedom. Superimposing harmonic currents on the redundant degrees of freedom suppresses the radial force. The performance of the proposed suppression scheme is evaluated using finite element analysis and experimental results. The scheme targets the generated second-order component, which is larger than the other order components. The results indicate that harmonic current can suppress the second-order radial force and second-order radial acceleration on the stator core. Superimposing the harmonic current suppresses the second-order radial acceleration from 0.0865 to 0.0082 m/s2, and the suppression effect is 90.5%.

High-speed switching with wide bandgap semiconductor switches is increasingly being applied to motor drive sys- tems in electric vehicles. However, the MHz ringing phenomenon caused by high-speed switching leads to an increase in losses in magnetic materials of the motors. This letter proposes a low-pass filter (LPF) to suppress the MHz ringing phenomenon. And, it demonstrates that the use of the proposed LPF results in the reduction of iron and copper losses.