Yasushi Kusaka

Novel Power Conversion System for Cost Reduction in Vehicles with 42V/14V Power Supply

In recent years, attention is being given to 42V power supply technology for solving the problem of increased power demand in vehicles. Since 2001, Toyota Motor Corporation has been marketing a mild hybrid system (THS-M) in order to further improve fuel economy and reduce emissions; this system requires both 42V and 14V power sources. The THS-M system consists of a 42V motor generator (M/G) connected to the engine crankshaft with a belt; an inverter; a 36V battery; a DC/DC converter for stepping down the 42V power supply to a conventional 12V battery; and high-power related electrical components. These components require additional costs, which must be reduced in order to increase the sales volume of THS-M vehicles. We have devised a method to eliminate the conventional DC/DC converter from the THS-M, and as a result we have developed a new, revolutionary power conversion system (multi-function inverter). Instead of using a DC/DC converter, we derived a 14V power line from the neutral point of the motor generator, and added a reactor (a type of smoothing inductor) in this line for reducing ripple. In addition, we applied a new inverter switching system which allows us to simultaneously and independently control both the 14V and 42V system voltages, which are taken from the motor-generator drive, and connected to the 12V and 36V batteries, respectively. The paper reports on the principle of operation and the test results, including torque and efficiency characteristics of the multi-function inverter.

EPS System Analysis using Multi Domain Simulation for Power Network Design in a Vehicle

An EPS system requires large electrical power depending on steering torque. Recently, the required steering torque is getting larger especially for luxury sedans and large Sports Utility Vehicles. In heavy vehicles, the steering without driving and the emergency steering are becoming a very heavy load for a conventional 12 V battery system. Therefore, it is important to estimate the battery power management and the voltage behavior using the multi domain simulation for concept planning. The purpose of this research is to show that multi domain simulation is effective to discuss power electronics system and power network in the vehicle. This paper describes modeling method for an EPS system using VHDL-AMS. Static steering and dynamic steering results were validated in comparison with experimental data.

EPS system analysis using multi domain simulation for conventional 12V power network design in a vehicle

An EPS system requires large electrical power depending on steering torque. Recently, the required steering torque is getting larger especially for luxury sedans and large Sports Utility Vehicles. In heavy vehicles, the steering without driving and the emergency steering are becoming a very heavy load for a conventional 12V battery system. Therefore, it is important to estimate the battery power management and the voltage behavior using the multi domain simulation for concept planning. The purpose of this research is to show that multi domain simulation is effective to discuss power electronics system and power network in the vehicle. This paper describes modeling method for an EPS system using VHDL-AMS [1] [2]. Static steering and dynamic steering results were validated in comparison with experimental data

Control methods for induction machine directly coupled to engine

Abstract For the purpose of low fuel consumption and low emissions, we have developed a hybrid powertrain system with an induction machine directly coupled to the engine, and power capacitors as a power source, which offers such functions as starting and assisting the engine, and regenerating braking energy. This paper describes three different motor control methods suitable for such a system. The first is a method without using a conventional high-resolution speed sensor, the second, a method for high accuracy of torque control by rotor resistance estimation, and the third, a method for high efficiency by controlling the flux according to changes in DC link voltage.