400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-0790 Web: www.sae.org SAE TECHNICAL PAPER SERIES 2007-01-0271 Power Control Unit for High Power Hybrid System Yasuyuki Sakai an d Hiroshi Ishiyama DENSO CORPORATION Takaji Kikuchi TOYOTA MOTOR CORPORATION Reprinted From: Advanced Hybr id Vehicle Powertrains, 2007 (SP-2101) 2007 World Congress Detroit, Michigan April 16-19, 2007 By mandate of the Engin eering Meetings Board, th is paper has been approved for SAE publication upon completion of a peer review process by a minimum of three (3) industry experts under the supervision ofthe session organizer. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise,without the prior written permission of SAE. For permission and licensing requests contact:SAE Permissions 400 Commonwealth DriveWarrendale, PA 15096-0001-USAEmail: [email protected]: 724-776-3036Tel: 724-772-4028 For multiple print copies contact: SAE Customer Service Tel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Fax: 724-776-0790Email: Customer [email protected] ISSN 0148-7191 Copyright © 2007 SAE InternationalPositions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE.The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the pap er if it is publishe d in SAE Transactions. Persons wishing to submit papers to be considered for presentation or publication by SAE should send the manuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Meetings Board, SAE. Printed in USA Copyright © 2007 SAE International ABSTRACT The hybrid vehicle market is growing rapidly recently, while carmakers are planning to expand their lineup ofhybrid vehicles from the compact to the full-size. Tomake this rapid development possible, the Power ControlUnit (PCU) that controls traction motors of hybridvehicles is required both to be smaller in size for theease of packaging, and higher in output power to fulfillthe need for full-size vehicles. To achieve both of these targets, we have developed a PCU for the Lexus LS600h with higher output power pervolume through significantly improved cooling design forpower semiconductor chips by dissipating heat from bothsides of them. The following is an overview of thedeveloped technology. 1. INTRODUCTION Toyota has introduced the Toyota Hybrid System II(THS-II) since the 2004 Prius. A hybrid vehicle based onTHS-II employs a PCU that consists of a boost converterand two sets of inverters controlling each one of the twomotor/generators (MGs) [1]. Figure 1 shows a typicalschematic of a PCU main circuit for THS-II. It consists ofmany semiconductor switches. Two kinds of silicon chips,an Insulated-Gate Bipolar Transistor (IGBT) and a FreeWheeling Diode (FWD), are paired in parallel to form areverse-conductive switch. The PCU is required both to be smaller in size to fit in the engine compartment, and to have higher output power topropel heavier vehicles, resulting in a need for higheroutput power per volume, or higher power density. When converting an existing gasoline-powered vehicle design to a hybrid version, the space factor in the enginecompartment is often so tight that there is no room for aPCU to fit in. The only component that can be removedfrom the engine compartment is the 14V lead-acidbattery, because its peak current to drive the starter motor is no longer required and it isn’t necessary to beclose to the engine. If a PCU is sized and shaped as thelead-acid battery, then it can replace the 14V battery.Toyota has taken this method since 2006 in the LexusGS450h, the CAMRY Hybrid, and the Estima Hybrid [2]. Battery2 1MG 288V650V max. Inverter 1 Inverter 2Boost ConverterMG Battery2 1MG 288V65