Toshiya Hisada

Measurement and analysis of impulsive noise on in-vehicle power lines

In-vehicle signal transmission requires dedicated communication cables such as twisted metal wires and optical fiber cables, which increase the weight and the volume of wiring harnesses in vehicles. Furthermore, the number of electronic control units (ECUs) and the other electronic devices in vehicles is increasing. As a result, in-vehicle networks are becoming more and more complex and unstable. In-vehicle power line communication (PLC) system has been proposed to carry out signal transmissions between ECUs via in-vehicle power lines. The in-vehicle PLC system simplifies in-vehicle networks and reduces the weight and the volume of wiring harnesses. To design communication systems, we analyze communication environments which are mainly characterized by propagation channels and additive noise. In this paper, the measurement and the analysis of frequency responses for in-vehicle power lines are presented to analyze the propagation channels. Thus we observe frequency-selective fading channels which have several notches in the frequency domain because of reflection of signals at impedance mismatching points.We also analyze the noise and the interference in order to design reliable communication systems. For this purpose, the measurement and analysis of the noise on in-vehicle power lines are presented. A lot of bursty impulsive noises are observed while actuators in vehicles are active. A time-frequency analysis is applied to the observed noise and we show time-varying frequency spectra of the observed noise. Finally, we discuss in-vehicle PLC schemes which are suitable for signal transmissions.

Statistical impulse detection of in-vehicle power line noise using hidden Markov model

Control signal networks in vehicles using dedicated communication cables such as twisted wires and fiber optics cables have been built in order to communicate between electronic control units (ECUs). However, there are problems such as the increase in weight of the cable harness and the difficulty to insure the reliability of complicated network architectures. Communication systems using in-vehicle power lines have been investigated. This paper proposes an impulse detection scheme and its four criteria to decide the impulse occurrence in a communication cycle by using the two-state hidden Markovian-Gaussian noise model for noise on in-vehicle power lines. The new scheme involves the maximum a posteriori (MAP) estimation using the Baum-Welch (BW) algorithm and the moment method to estimate the model parameters. The proposed scheme is applied to noise generated from the hidden Markov model and noise observed on in-vehicle power lines and investigate their detection accuracy. It is shown that the detection accuracy is substantially improved by using an impulse occurrence criterion based on the number of free parameters.

Capacity determination of a battery energy storage system based on the control performance of load leveling and voltage control

AbstractThis paper proposes a method to determine the combined energy (kWh) and power (kW) capacity of a battery energy storage system and power conditioning system capacity (kVA) based on load leveling and voltage control performances. Through power flow calculations, a relationship between the capacity combination and the control performance is identified and evaluated. A tradeoff relationship between the capacity combination and control performance is confirmed, and the proper capacity combination for operation is determined based on the evaluated relationship. In addition, the control performance of the capacity combination is evaluated through the power flow calculation, confirming that the proposed method is effective for determining the optimized capacity combination.