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Gradationally Controlled Voltage Inverter for More Electric Aircrafts

Mitsubishi Electric Corp.-Tetsuya Kojima, Masahiro Sugahara, Yusuke Shirouchi, Hisatoshi Fukumoto, Akihiko Iwata
IHI Corporation-Hitoshi Oyori
  • Technical Paper
  • 2019-01-1913
To be published on 2019-09-16 by SAE International in United States
Over recent decades, there has been a lot of progress toward a more electric aircraft (MEA) to reduce emissions and fuel consumption. In MEAs, many subsystems that previously used hydraulic or pneumatic power have been replaced by electrical systems with inverters and electrical machines. Therefore, MEAs reduce the weight, i.e. fuel consumption, and maintenance cost. To achieve advanced electrical systems, the weight of inverters has significant importance. In this work, a gradationally controlled voltage (GCV) inverter is proposed to reduce the weight and enhance reliability. A GCV inverter can supply gradational quasi-sinusoidal voltages combining two different voltages from a 3-phase 3-level (main) inverter and three single-phase H-bridge (sub) inverters. A dc power supply is required only for the main inverter. A main inverter with Si-IGBTs supplies the fundamental voltage by only one switching in the fundamental period. Consequently, the switching loss is minimized and hence the weight of cooling systems can be reduced. Sub inverters, which have the half of dc-link voltage of the main inverter, employ SiC-MOSFETs with higher switching frequency and compensate for…
 

A Study on Accomplishing Lean Combustion by Multistage Pulse Discharge Ignition Using an Optically Accessible Engine

Mitsubishi Electric Corp.-Taichiro Tamida, Takahiro Inoue
Nihon University-Yosuke Abe, Masaya Iimura, Takuma Furusho, Kotaro Takeda, Akira Iijima
Published 2018-10-30 by SAE International in United States
Lean burn technology has a problem of greater combustion fluctuation due to unstable initial flame formation and slow combustion. It is generally known that generating a flow field in the cylinder is effective for reducing combustion fluctuation and shortening the combustion period. In this study, we investigated the influence of the discharge condition and in-cylinder swirl flow on initial flame formation and ignition performance between conventional spark ignition (SI) and multistage pulse discharge (MSPD) ignition. Visualized photographs were obtained near the spark plug with a high-speed camera in an optically accessible engine. In-cylinder pressure analysis was also performed in order to explicate the combustion phenomena. The results revealed that ignition performance of both SI and MSPD was improved under a swirl flow condition in the cylinder and that combustion fluctuation was effectively reduced. Under the generation of in-cylinder swirl flow, the effect on reducing combustion fluctuation was greater with MSPD than with SI, and more stable combustion was obtained.
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Study of Discharge under Swirl Flow and Combustion Conditions

Mitsubishi Electric Corp.-Takahiro Inoue, Taichiro Tamida
Published 2018-10-30 by SAE International in United States
Combustion at a high EGR (Exhaust Gas Recirculation) ratio is an effective means for improving the fuel efficiency of a gasoline engine. However, there is a problem that the combustion speed decreases. So, it is necessary to intensify the in-cylinder flow to ensure the combustion speed. The spark discharge generated by the ignition coil is strongly influenced by the in-cylinder flow. It forms an arcuate discharge path along the flow, and may blow off and re-discharge under a strong gas flow. The behavior of spark discharge strongly affects the ignition, and consequently affects the stability of combustion. However, the phenomena in a combustion chamber are very complicated because of various environmental conditions, and the discharge and combustion phenomena under a strong gas flow remain unclear. In this research, in order to study these phenomena, discharge and combustion experiments under flow using a constant volume container were performed. We observed discharge channel and length from the images obtained by high-speed camera, and calculated the discharge resistance from the voltage and current waveforms of the plug, and…
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Development of Autonomous Driving System Using GNSS and High Definition Map

Mitsubishi Electric Corp.-Yu Takeuchi, Tanaka Hideyuki, Hitosugi Kazuo, Uno Tomoki
Published 2018-04-03 by SAE International in United States
Recently, development of vehicle control system targeting Full Driving Automation (autonomous driving level 5) has advanced. Some applications of autonomous driving systems like the Lane Keeping Assist system (LKA) and Auto Lane Change system (ALC) (autonomous driving level 1-3) have been put on the market. However, the conventional system using information from front camera, it is difficult to operate in some situations. For example the road that no line, large curvature and number of lane increases or decreases.We propose an autonomous driving system using high accuracy vehicle position estimation technology and a high definition map. An LKA system calculates the target steering wheel angle based on both vehicle position information from the Global Navigation Satellite System (GNSS) and the target lane of high the definition map, according to the method of front gaze driver model. Then, the system controls steering the wheel angle by Electric Power Steering (EPS). In the case of ALC, a target lane-change path is generated based on information of the vehicle’s own lane and the next one.The proposed system solved the…
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Development of Lane Keeping Assist System Using Lateral-Position-Error Control at Forward Gaze Point

Mitsubishi Electric Corp.-Takayuki Tanaka, Shunsuke Nakajima, Takahiro Urabe, Hideyuki Tanaka
Published 2016-04-05 by SAE International in United States
Mitsubishi Electric has been developing a lane keeping assist system (LKAS). This system consists of our products such as an electric power steering (EPS), a camera, and an electronic control unit (ECU) for ADAS. In this system, the camera detects a lane marker, the ECU estimates reference path and vehicle position, and calculates reference steering wheel angle, and the EPS controls a steering wheel angle based on reference steering wheel angle. In this paper, we explain the calculation method of reference steering wheel angle for path tracking control. We derive a formula of reference steering wheel angle calculation that converges lateral position deviation in desired time by using lateral position deviation change rate control on forward gaze point as path tracking control algorithm. Since the formula is obtained from the vehicle model, we can easily design a controller depending on the vehicle type, by using known vehicle specifications. In addition, we confirmed that the algorithm can be used for LKAS by simulation and examination. The algorithms uses just the lateral position deviation, yaw angle deviation…
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Development of High Speed Motor and Inverter for Electric Supercharger

Mitsubishi Electric Corp.-Kazuhiro Nishiwaki, Masahiro Iezawa, Hideyuki Tanaka, Takashi Goto
Mitsubishi Heavy Industries, LTD.-Byeongil An
Published 2013-04-08 by SAE International in United States
In recent years, the fuel consumption improvement of automobiles is indispensable due to the global move to reduce CO₂ emissions. Downsizing of engines by turbocharger obtains the output equal to a large engine, and improves the fuel consumption. However, turbocharger has the response delay called turbo lag. In order to improve a transient response, we developed a high-speed motor. The electric supercharger consists of high-speed motor and compressor, and drives compressor by high-speed motor instead of an exhaust gas turbine. By combining conventional turbocharger and electric supercharger, we developed two-stage turbocharger system.In this paper, we explained development of high-speed motor and inverter. And, as application example, we explained electric two-stage turbocharger system. The high-speed motor and inverter are connected without harness, and assembled in one single unit. The motor is driven at high efficiency by vector control. The performance test shows a high speed response of 0.7 sec acceleration time from zero to maximum speed 90,000 rpm. Electric two-stage turbocharger, applying high-speed motor, is evaluated by engine simulation tool (GT-Power) and engine bench test. As…
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High Efficiency Isolated AC-DC Converter with Gradationally Controlled Voltage Inverter for On-Board Charger

SAE International Journal of Alternative Powertrains

Mitsubishi Electric Corp.-Takashi Kaneyama, Kazutoshi Awane, Mamoru Takikita, Naohisa Uehara, Ryota Kondo, Masaki Yamada
  • Journal Article
  • 2013-01-1756
Published 2013-04-08 by SAE International in United States
A new isolated AC-DC converter for an on-board charger has been developed. It consists of an AC-DC converter with Gradationally Controlled Voltage Inverter and an isolated zero-voltage-switching DC-DC converter. To make these converters cooperate efficiently over the wide range of operating voltage conditions, we developed an optimized converter control. As a result, the new isolated AC-DC converter can operate with power conversion efficiency of over 94%.
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Luminance Control of In-Vehicle Display Based on Visual Field Driving Environment (First Report)

Mitsubishi Electric Corp.-Atsushi Shimada, Yoshitomo Nakamura
Seikei Univ.-Masanori Takemoto, Satoru Kuobta
  • Technical Paper
  • 2012-08-0433
Published 2012-10-03 by Society of Automotive Engineers of Japan in Japan
Visual field luminance determines the optimum display luminance necessary for adequate visibility. In this study, we developed a method that estimates the luminance level of a driver's visual field using an illuminance sensor and investigated its actual characteristics. We then simulated the visual field of a driver's seat environment under experimental conditions. In our experiments, test subjects evaluated the optimum display luminance of a car-navigation system under static conditions, with variations added to simulate time of day and weather. As a result, we obtained an equation that predicts the adequate display luminance level based on driver's visual field luminance level.
 

Lane Departure Warning System Using Rearview Camera

Mitsubishi Electric Corp.-Shintaro Watanabe, Makito Seki, Tetsuji Haga, Hiroshi Kage, Takashi Hirai
  • Technical Paper
  • 2011-08-0048
Published 2011-10-12 by Society of Automotive Engineers of Japan in Japan
It is difficult to detect lane positions using a rearview camera because of combined problems, for instance, low illumination at night, and headlight glare from following cars. In this paper, we propose a robust lane detection method based on vanishing point tracking using particle filter and Hough transform.
 

Use of Multi-Modal Detection Task to Assess Driver's Cognitive Workload

Mitsubishi Electric Corp.-Atsushi Shimada, Masaharu Wakamatsu
Kansai University of Welfare Sciences-Takahiko Kimura
  • Technical Paper
  • 2010-08-0477
Published 2010-09-29 by Society of Automotive Engineers of Japan in Japan
This study examined the availability of the multi-modal detection task as an assessment tool of mental workload. An experiment involving simulated driving while performing some secondary tasks including operation of a car navigation and a handheld cell phone was conducted. Result showed that the reaction time and detection error increased when participants performed secondary tasks as compared with the baseline driving and that reaction profiles to each stimulus task varied according to the experimental condition, suggesting that the multi-modal detection task is useful for assessing both the quantitative and qualitative aspect of mental workload induced by engaging in an in-vehicle task.