Apr. 17, 2003
Toyota's Develops New Hybrid System
High-voltage Control Architecture Increases Efficiency,
Tokyo―TOYOTA MOTOR CORPORATION announced today it has completed a next-generation hybrid system that radically enhances the synergy between electric motor and internal combustion engine by employing a high-voltage power-control system for greater motor output. THS II―developed under Toyota's "Hybrid Synergy Drive" concept―boasts improved environmental performance and drastically raises the "fun to drive" quotient for hybrid vehicles.
The new system represents the latest evolutionary stage in Toyota hybrid technologies, starting with those constituting the Toyota Hybrid System (THS) that powered the Toyota Prius into history books in 1997 as the world's first mass-produced hybrid passenger vehicle. Like THS, THS II places greater emphasis on the role of the motor than do systems that use a low-output motor to temporarily supplement a primary-drive-force engine.
As the world's leading manufacturer of hybrid vehicles, Toyota has aimed to revolutionize the automobile for the 21st century. Following the Prius, it introduced the THS-C-driven Estima Hybrid featuring a continuously variable transmission and the THS-M-propelled mild hybrid Crown, both in 2001. The technologies used in THS and its derivatives made possible the commercial launch of the TOYOTA FCHV fuel cell hybrid vehicle in 2002. Toyota has now sold more than 130,000 hybrid vehicles worldwide.
Plans include efforts to heighten THS II’s performance for application in heavy vehicles that require larger engines. The next-generation Prius, which features the new system, is currently on display at the ongoing New York International Automobile Show.
|At acceleration from start and at low to mid-range speeds
The engine is stopped when it encounters a poor-efficiency range under a wider range of operational conditions such as acceleration from standing start and up to mid-range speed. The vehicle runs entirely on power generated by the motor.
|During driving under normal conditions
Power generated by the engine is distributed two ways by the power split device. One power stream is used to drive the generator, which in turn drives the motor. The other power stream is used to directly drive the wheels. The distribution of these power streams is controlled to provide maximum efficiency.
|During sudden acceleration
During sudden acceleration, extra power is supplied from the battery while the engine adds drive to the high-output motor, providing good response and a smooth drive, as well as improved acceleration performance.
|During deceleration, such as through braking
During deceleration, such as through braking, the high-output motor functions as a large capacity generator, controlling power distribution to the wheels. The system functions as an efficient regenerative braking system recovering the vehicle's kinetic energy as electrical energy. The recovered energy is then stored in the high-performance battery.
|While the battery is recharging
The battery is controlled to maintain a certain level of charge. When the charge level becomes low the generator kicks in to recharge it.
|When the vehicle is stopped, the engine automatically stops.|
(high-expansion ratio cycle)
(high-expansion ratio cycle)
|Maximum output in kw (Ps)/rpm||57 (78)/5,000||53 (72)/4,500|
|Maximum torque in N-m (kg m)/rpm||115 (11.7)/4,200||115 (11.7)/4,200|
|Motor||Type||Synchronous AC motor||Synchronous AC motor|
|Maximum output in kw (Ps)/rpm||50 (68)/1,200 – 1,540||33 (45)/1,040 – 5,600|
|Maximum torque in N-m (kg m)/rpm||400 (40.8)/ 0 – 1,200||350 (35.7)/ 0 - 400|
in kW (Ps)/vehicle speed km/h
|82 (113)/85 or higher||74 (101)/120 or higher|
|Output at 85km/h in kW(PS)||82 (113)||65 (88)|
in N-m (kg m)/vehicle speed km/h
|478 (48.7)/22 or lower||421 (42.9)/11 or lower|
|Torque at 22km/h in N-m (kg m)||478 (48.7)||378 (38.5)|
|Battery||Type||Nickel-metal hydride||Nickel-metal hydride|