System Description

HYBRID / BATTERY CONTROL: HYBRID CONTROL SYSTEM: SYSTEM DESCRIPTION

1. OPERATION

(a) Operation of Hybrid Vehicle

(1) The hybrid system uses motive force provided by the engine and MG2, and it uses MG1 as a generator. The system optimally combines these forces in accordance with various driving conditions.

(2) The power management control ECU (HV CPU) constantly monitors the engine coolant temperature, SOC, HV battery temperature and electrical load conditions. If any of the monitoring conditions fails to satisfy the requirements, and when the vehicle is in the READY-on state and the shift position is any positions other than N, the power management control ECU (HV CPU) starts the engine.

(3) The hybrid system drives the vehicle by optimally combining the operations of the engine, MG1 and MG2 in accordance with the driving conditions listed below. The vehicle conditions listed below are examples of typical vehicle driving conditions.









(b) Driving Condition B: Starting Off

(1) When the vehicle is started off, the vehicle operates powered by MG2. If the required drive torque increases when running with MG2 only, MG1 is activated to start the engine.





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(c) Driving Condition C: Constant-speed Cruising

(1) When the vehicle is running under low load and constant-speed cruising, the motive force of the engine is transmitted by the power split planetary gear unit. Some of this motive force is output directly, and the remaining motive force is used for generating electricity through MG1. Through the use of the electrical power path of an inverter, this electrical power is transmitted to MG2 to be output as the motive force of MG2. If the SOC level of the HV battery is low, it is charged by MG1 driven by the engine.





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(d) Driving Condition D: During Full Throttle Acceleration

(1) When the vehicle driving condition changes from low load cruising to full-throttle acceleration, the system supplements the motive force of MG2 with electrical power from the HV battery.





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(e) Driving Condition E: During Deceleration

(1) While the vehicle decelerates with drive (D) selected, the engine is turned off and the motive force changes to zero. At this time, the wheels drive MG2, causing MG2 to operate as a generator, charging the HV battery. If the vehicle decelerates from a higher speed, the engine maintains a predetermined speed without stopping, in order to protect the planetary gears.





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(f) Driving Condition F: During Reverse

(1) When the vehicle is being driven in reverse, the required power is supplied by MG2. At this time, MG2 rotates in the opposite direction, the engine remains stopped, and MG1 rotates in the normal direction without generating electricity.





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2. SYSTEM DIAGRAM









3. FUNCTION OF MAIN COMPONENTS

(a) The main components of the hybrid system have the following functions: