Katsuhiro Hata

A dynamic wireless power transfer (WPT) system for electric vehicles can extend their cruising distance and reduce the size of their energy storage system. Power control and efficiency maximization of WPT are preferable to be controlled on the secondary side because ground facilities of the dynamic charging system have to be simplified. Although previous research has proposed a secondary-side simultaneous control of the maximum efficiency and the desired power, the battery charging current canno

A dual-path hybrid DC-DC converter with the step-down ratio of less than half is proposed for the first time. In the proposed converter, the efficiency is higher than a conventional buck converter, because the output current is divided into inductor- and capacitor-path and the conduction loss due to ESR of the inductor is reduced. In the measurement, the peak efficiency of the proposed dual-path hybrid and conventional buck converters was 97.1% and 96.0% at 120W, 48V-to-12V conversion, respectiv

Wireless charging for moving electric vehicles could extend their cruising distance. Wireless power transfer via magnetic resonant coupling is suitable for this application. The transmitting efficiency can be maximized by using a DC-DC converter on the secondary side. The control system, however, must be designed properly to satisfy the response requirements depending on motion of the vehicle. Previous controllers were designed without considering the dynamics of the DC-DC converter for wireless

An always-dual-path hybrid (ADPH) DC-DC converter using one inductor and two flying capacitors with the step-down ratio from 3:1 to 1:1 is proposed to achieve high efficiency at the commonly used 2:1 step-down ratio by reducing the inductor current. The proposed ADPH converter is designed for a 24 V-to-13 V bus converter for truck auxiliary equipment. In the measurement, the peak efficiency of the proposed 24 V-to-13 V converter is 97.4 % at 146 W, and the inductor conduction loss is reduced by

In-motion wireless power transfer (WPT) system is expected to achieve unlimited driving range of electric vehicles (EV s) independent of their battery capacity. Previous research has developed an in-motion WPT system with individual vehicle detection units for power transmission control. However, in this paper, a charging infrastructure of in-motion WPT is designed and implemented based on a sensorless vehicle detection system only using power converters and power transmitting coils. In addition

Wireless power transfer (WPT) via magnetic resonance coupling has gathered attentions because of its high transmitting efficiency and robustness to misalignment. The efficiency characteristics of the WPT system are expressed by kQ product, which is given by coupling coefficient and quality factors of a transmitter and receiver. However, a conventional measuring method of the kQ product is quite burdensome because it requires to remove the resonance capacitors of the transmitter and receiver and

This paper focuses on the way to use the EDLC bank in a small electric vehicle (EV). In a recent study of an EV, a supercapacitor (EDLC; Electric Double Layer Capacitor) is adopted into an energy storage system to improve energy efficiency. Generally, the EDLC bank consists of a large number of cells because the EDLC bank cell voltage is very small compared with the battery terminal voltage, which is a DC bus voltage in the motor drive system. On the other hand, a small EV cannot be equipped wit

In-motion wireless power transfer (WPT) has the capability to drastically increase a cruising distance of electric vehicles (EVs). A vehicle detection technique is important for a road facility to reduce standby power consumption and to prevent an unnecessary magnetic field leakage. A sensorless vehicle detection method using voltage pulses has been proposed and fundamental experiments have been demonstrated with small-scale equipment. In this paper, a full-scale in-motion WPT system is implemen

A dynamic wireless power transfer (WPT) system for electric vehicles (EVs) has gathered attention and been expected to extend the limited driving range of EVs. Previous research has proposed secondary-side-only power and efficiency control to simplify the road-side facilities, which are installed over long distances. Although the primary voltage and the mutual inductance between the transmitter and receiver have to be given or estimated in the control, multi-parameter estimation from the seconda

Electric vehicles (EVs) have environmental advantages and the capacity for advanced motion control. However, EVs need to be charged frequently due to their limited mileage per charge. A dynamic wireless power transfer (WPT) system for EVs can extend their cruising distance and reduce the size of their energy storage system. However, when being applied to rugged roadways over long distances, it is important to simplify ground facilities as much as possible. While it is practical for a static syst

In-motion charging of electric vehicles (EVs) is expected to drastically increase the driving range of EVs. In order to keep enough charging time during high-speed driving, a transient response of an in-motion wireless power transfer (WPT) system should be improved. In this paper, an implemented in-motion WPT system is presented as an example of system development methodologies and a start-up control method with input shaping is proposed. The experiments show that the proposed method can suppres

In-motion charging of electric vehicles is required to achieve accurate vehicle detection and a quick start-up operation for keeping enough charging time. However, a transient response of wireless power transfer (WPT) may cause a huge current overshoot and it should be carefully considered to prevent overload damage and to reduce current stress on power converters. In this paper, a ramp-up based soft-start control method is proposed and the start-up time of the control is designed based on the t

A dynamic wireless charging system for electric vehicles (EVs) is expected to extend the limited driving distance of EVs. As the transmitting efficiency changes according to motion of the vehicle in dynamic charging, an efficiency maximization method is important. Previous research has proposed secondary-side efficiency control based on mutual inductance estimation to simplify the ground facilities, which would be installed over long distances. However, the ground facilities have to regulate the

A novel circuit topology for 48 V-to-12 V always-dual-path hybrid (ADPH) DC-DC converters is proposed using one inductor and two flying capacitors with only two circuit states to reduce the inductor DC current by 50 % compared to a conventional buck converter. The loss analysis shows that the proposed ADPH converter can achieve higher efficiency than the conventional buck converter over the entire output current range of the 48 V-to-12 V conversion. In the measurement, the efficiency at 15 A <in