System Description

WARNING: This page is about a different car, the 2004 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

GENERAL
The THS-II control system consists of the following controls.

Fig 1: THS-II Control System Table (1 Of 2)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: THS-II Control System Table (2 Of 2)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
BASIC OPERATION
1. This system controls the following modes in order to achieve the most efficient operations to match the driving conditions:
  1. Supply of electrical power from the HV battery to MG2 provides force to drive the wheels.
    
    Fig 3: Supplying Electrical Power From HV Battery To M62 (1 Of 2)
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. While the wheels are being driven by the engine via the planetary gear, MG1 is rotated by the engine via the planetary gears, in order to supply the generated electricity to MG2.
    
    Fig 4: Supplying Electrical Power From HV Battery To M62 (2 Of 2)
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. MG1 is rotated by the engine via the planetary gear, in order to charge the HV battery.
    
    Fig 5: Adjusting M61 Rotated By Engine Via Planetary Gear
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  4. When the vehicle is decelerating, kinetic energy from the wheels is recovered and converted into electrical energy and used to recharge the HV battery by means of MG2.
  Fig 6: Using To Recharged HV Battery By Means Of M62
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. The HV control ECU switches between these modes ((1), (2), (3), (1) + (2) + (3), or (4)) according to the driving condition. However, when the SOC (State of Charge) of the HV battery is low, the HV battery is charged by the engine by turning MG1.
As a result, it achieves far greater fuel economy compared to conventional gasoline engine vehicles, at a reduced level of exhaust gas emissions. Furthermore, this revolutionary power-train has eliminated the constraints that are associated with electric vehicles (such as their short cruising range or their reliance on external recharging units).
SYSTEM DIAGRAM

Fig 7: Hybrid Control System Diagram
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
FUNCTION OF MAIN COMPONENTS

Fig 8: Hybrid Control System Main Components List

*: Only on model with Enhanced VSC System