Summary of Research Project Results under JSPS FY2003
"Research for the Future Program"

1.Research Institution Nagoya Institute of Tcchnology
2.Research Area Physical and Engineering Sciences
3.Research Field Reduction of Electromagnetic Noise Levels
4.Term of Project FY 1999 - FY 2003
5.Project Number 99P01503
6.Title of Project Control of Electromagnetic Environment in Low Frequency Band Less than 100 kHz

7.Project Leader
Name Institution,Department Title of Position
Nobuyuki,Matsui Nagoya Institute of Technology President

8.Core Members

Names Institution,Department Title of Position
Tsutomu,Ohmae Chuo University, Faculty of Science and Engineering Professor
Kouhei,Ohnishi Keio University, Faculty of Science and Technology Professor

9.Summary of Research Results

   With an increase in the number of the power electronics equipments, the associate problem of the conducted electromagnetic noise generated by the high-speed switching operation is becoming more serious. In order to reduce the conducted electromagnetic noise in low frequency band, the research was promoted from two points of view as follows.
1. Reduction of Noises for Individual Equipments

(1) To reduce the common-mode noise generated by the switched-mode power converters, the basic design circuit concept of a balanced switching converter was proposed. By using the proposed concept, more than 20 dB noise reduction was possible. Also, more than 20 dB noise reduction was possible using the common-source type active-clamp technique and more than 40 dB noise reduction was possible by the developed super-low-noise switched-mode power converter.

(2) To reduce the common-mode noise of the converter-inverter system for motor drives, a new inverter multi-layer printed board was proposed. In addition, the new printed circuit boards for input and output ac lines of the inverter were proposed to suppress the common mode noises. Using the proposed method, 10-25 dB noise reduction was confirmed by experiments.
2. Suppression of Harmonics for Consumer and Distribution System

(1) In the source current detection type active filter to suppress the outflow of the harmonic current from consumer, a general-purpose control algorithm was developed by which the anti-resonance as well as the line harmonic was effectively damped.

(2) To measure and examine the harmonics flow in the distribution system, the multi-points synchronized measurement system was developed. Using the high performance DSP and recursive DFT, the 6-ch, 60 kHz-sampling real time analysis of harmonics was realized at 3 kHz measurement frequency.

(3) Using the developed multi-points synchronized measurement system above, a new control scheme for series active filter was proposed, by which the effective suppression without local harmonic propagation was confirmed by experiments.

10.Key Words
(1)electromagnetic noise   (2)harmonics suppression   (3)motor drive system
(4)switched-mode power converter   (5)active filter   (6)Multi-points synchronized measurement
(7)common-mode noise   (8)power distribution system   (9)Route Control