Energy Recovery When The Engine Overruns

The BISG  recovers energy when the engine overruns to generate electric energy. This electric energy is stored in the MHEV  battery for used by the DC/DC  and the BISG  when required.

The recovered energy improves the fuel economy of the vehicle by 2 methods:

• Reducing the power generated by the BISG  using engine power to supply the DC/DC  .
• Assisting the engine by using the recovered energy to power the BISG  to reduce the fuel used by the engine for a given torque requirement.

The PCM  uses data from various modules to determine the amount of energy that can be recovered from the engine overruns. The PCM  uses sensors data and others from these:

• Accelerator Pedal Position (APP) sensor
• Engine speed
• Vehicle speed
• MHEV  battery state of charge
• Transmission gear.

When driving a MHEV  , the driver may notice increased engine braking when the engine overruns, this is normal operation.