Charge depletion control method and apparatus for hybrid powered vehicles

A method of operating a hybrid electric vehicle having an electric motor, a battery powering the electric motor, and an auxiliary power unit, comprising the steps of:

• (a) sensing the speed of the vehicle;
• (b) sensing the level of the depth of discharge of the battery;
• (c) at vehicle speeds above a first threshold speed, activating the auxiliary power unit to power the vehicle and using the electric motor to supplement the auxiliary power unit when required;
• (d) at vehicle speeds below a second threshold speed, deactivating the auxiliary power unit and using the electric motor to power the vehicle;
• and
• (e) automatically and dynamically adjusting at least one of said first and second threshold speeds as a function of said level of the depth of discharge.

An apparatus for controlling operation of a hybrid powered vehicle having an electric motor, a battery powering said electric motor, and an auxiliary power unit, comprising:

• (a) means for sensing the speed of the vehicle;
• (b) means sensing the level of the depth of discharge of the battery;
• (c) means, at vehicle speeds above a threshold speed, for activating said auxiliary power unit to power said vehicle and for using said electric motor to supplement said auxiliary power unit when required;
• (e) means, at vehicle speeds below said threshold speed, for deactivating said auxiliary power unit and using said electric motor to power said vehicle;
• (f) means for automatically dynamically adjusting said threshold speed as a function of said level of the depth of discharge.

A control apparatus for a hybrid powered vehicle having an electric motor, a battery powering the electric motor, and an auxiliary power unit, comprising:

• (a) means for sensing the speed of the vehicle;
• (b) means for sensing the level of the depth of discharge of the battery;
• (c) means for, at vehicle speeds above a first threshold speeds activating the auxiliary power unit to power the vehicle and using the electric motor to supplement the auxiliary power unit when required;
• (d) means for, at vehicle speeds below a second threshold speed, deactivating the auxiliary power unit and using the electric motor to power the vehicle;
• (f) means for automatically and dynamically adjusting at least one of said first and second threshold speeds as a function of said level of the depth of discharge.

A method of controlling the operation of a hybrid electric vehicle having an electric motor, a battery powering the electric motor, and an auxiliary power unit, comprising the steps of:

• (a) charging the battery from a power source external to the vehicle;
• (b) sensing the speed of the vehicle;
• (c) sensing the level of the depth of discharge of the battery;
• (d) at vehicle speeds above a threshold speed, automatically activating the auxiliary power unit to power the vehicle and using the electric motor to supplement the auxiliary power unit when required;
• (e) at vehicle speeds below the threshold speed, automatically deactivating the auxiliary power unit and using the electric motor to power the vehicle until the battery charge is substantially depleted;
• and
• (f) recharging the battery from at least one of the following:
• (i) said auxiliary power unit;
• (ii) regenerative braking;
• and
• (iii) a power source external to the vehicle.

A method of controlling the operation of a hybrid electric vehicle having an electric motor, a battery powering the electric motor, and an auxiliary power unit, comprising the steps of:

• (a) sensing the speed of the vehicle;
• (b) sensing the level of the depth of discharge of the battery;
• (c) at vehicle speeds above a threshold speed, activating the auxiliary power unit to power the vehicle and using the electric motor to supplement the auxiliary power unit when required;
• (d) at vehicle speeds below the threshold speed, deactivating the auxiliary power unit and using the electric motor to power the vehicle;
• (e) automatically and dynamically reducing the threshold speed as the depth of discharge increases, wherein the charge on said battery is depleted by operation of said electric motor;
• and
• (f) recharging the battery under a condition selected from the group comprising:
• (i) when said battery is in a substantially depleted state;
• (ii) when said battery is in a fully depleted state.