Method of controlling electric vehicle driven by an internal combustion engine

Claim 1

A method of controlling the power operation of a vehicle having an AC generator driven by an internal combustion engine, a first power convertor for converting the AC generator output to DC voltage, an intermediate DC circuit having an input connected to output of the first power converter, a second power converter for converting the DC output of the intermediate circuit to an AC voltage, AC induction motors connected to the output of the second power convertor for driving the vehicle wheels, and breaking resistors in the intermediate DC circuit for consuming power during vehicle braking said method including the steps of: controlling the AC voltage output of the generator during a first speed range of the vehicle from zero to a predetermined first vehicle speed to maintain a first substantially constant DC voltage in the intermediate circuit; controlling the voltage output of the generator during a second speed range of the vehicle from the first predetermined vehicle speed to a second predetermined vehicle speed higher than said first predetermined vehicle speed to increase the DC voltage in the intermediate circuit in proportion to said vehicle speed; controlling the AC voltage output of the generator during a third speed range of the vehicle from the predetermined second speed to a predetermined third speed higher than the second predetermined speed, maintaining a second substantially constant DC intermediate circuit voltage; varying the frequency of the AC voltage output of the second power convertor during the first, second and third speed ranges and the amplitude of the AC voltage output of the second power convertor during the first and second speed ranges; and maintaining the AC voltage output of the second power converter substantially constant during the third speed range.

Claim 2

A method of controlling the power operation of a vehicle having an AC generator driven by an internal combustion engine, a first power convertor for converting the AC generator output to DC voltage, an intermediate DC circuit having an input connected to output of the first power converter, a second power converter for converting the DC output of the intermediate circuit to an AC voltage, AC induction motors connected to the output of the second power convertor for driving the vehicle wheels, and breaking resistors in the intermediate DC circuit for consuming power during vehicle braking said method including the steps of: controlling the AC voltage output of the generator during a first speed range of the vehicle from zero to a predetermined first vehicle speed to maintain a first substantially constant DC voltage in the intermediate circuit; controlling the voltage output of the generator during a second speed range of the vehicle from the first predetermined vehicle speed to a second predetermined vehicle speed higher than said first predetermined vehicle speed to increase the DC voltage in the intermediate circuit in proportion to said vehicle speed; controlling the AC voltage output of the generator during a third speed range of the vehicle from the predetermined second speed to a predetermined third speed higher than the second predetermined speed, maintaining a second substantially constant DC intermediate circuit voltage; varying the frequency of the AC voltage output of the second power convertor during the first, second and third speed ranges and the amplitude of the AC voltage output of the second power convertor during the first and second speed ranges; and maintaining the AC voltage output of the second power converter substantially constant during the third speed range.