This invention concerns an electric drive system (200) for driving an output. The electric drive system comprises: a first electric motor (250) arranged to drive a first input shaft (230) at a first angular velocity, ω.sub.1, and a second electric motor (260) arranged to drive a second input shaft (240) at a second angular velocity, ω.sub.2. A gear mechanism (210) is provided and is arranged to transmit angular rotation of the first (230) and second (240) input shafts to drive the output (220) at an output angular velocity, ω.sub.out, such that ω.sub.out is proportional to aω.sub.1-bω.sub.2, where a and b are constants. The electric drive system (200) further comprises a controller (270) arranged to control operation of the first (250) and second (260) electric motors. When the output (220) is to be driven from ω.sub.out=0, the controller (270) is arranged to control the first (250) and second (260) electric motors to drive the first (230) and second (240) input shafts. The input shafts are driven in a first phase to primary first and second angular velocities, ω.sub.1,p and ω.sub.2,p, such that aω.sub.1,p≈bω.sub.2,p. The input shafts are also subsequently driven in a second phase in which the first angular velocity, ω.sub.1, or the second angular velocity, ω.sub.2, or both are varied such that aω 1≠b.sub.ω2 and the output is driven from ω.sub.out=0. The result of this is that the motors run in a more efficient part of their output profile, even whilst the vehicle is at rest, pulling off (especially in situations of high output load such as on off-road or otherwise difficult terrain), or moving at low velocity.

This invention concerns an electric drive system (200) for driving an output. The electric drive system comprises: a first electric motor (250) arranged to drive a first input shaft (230) at a first angular velocity, ω.sub.1, and a second electric motor (260) arranged to drive a second input shaft (240) at a second angular velocity, ω.sub.2. A gear mechanism (210) is provided and is arranged to transmit angular rotation of the first (230) and second (240) input shafts to drive the output (220) at an output angular velocity, ω.sub.out, such that ω.sub.out is proportional to aω.sub.1-bω.sub.2, where a and b are constants. The electric drive system (200) further comprises a controller (270) arranged to control operation of the first (250) and second (260) electric motors. When the output (220) is to be driven from ω.sub.out=0, the controller (270) is arranged to control the first (250) and second (260) electric motors to drive the first (230) and second (240) input shafts. The input shafts are driven in a first phase to primary first and second angular velocities, ω.sub.1,p and ω.sub.2,p, such that aω.sub.1,p≈bω.sub.2,p. The input shafts are also subsequently driven in a second phase in which the first angular velocity, ω.sub.1, or the second angular velocity, ω.sub.2, or both are varied such that aω 1≠b.sub.ω2 and the output is driven from ω.sub.out=0. The result of this is that the motors run in a more efficient part of their output profile, even whilst the vehicle is at rest, pulling off (especially in situations of high output load such as on off-road or otherwise difficult terrain), or moving at low velocity.

A system for maintaining battery cycle life for motorized battery-powered electric vehicles. Current battery-powered electric vehicles such as automobiles and trucks suffer from short cycle life of their batteries, meaning that these vehicles' batteries will become unusable well before reaching the normal useful life of combustion engine powered vehicles. Owners of vehicles using my system will enjoy vehicles with acceptable ranges, acquisition and operating costs, yet will enjoy battery lifetimes as long or as longer than the useful life of combustion engine vehicles.

In an electrical traction drive for a vehicle comprising at least two individual wheel drives that are to be controlled independently of each other, the drives are able to be operated redundantly in order for an emergency operating function to be implemented.

In an electrical traction drive for a vehicle comprising at least two individual wheel drives that are to be controlled independently of each other, the drives are able to be operated redundantly in order for an emergency operating function to be implemented.

A drive mechanism includes a mount block extending along an axis and a plurality of electric motors supported by the mount block. The electric motors are arranged in series along the axis to define an initial electric motor, one or more intermediate electric motors, and a final electric motor. The drive mechanism also includes a gear mounted to each of the electric motors, and an output member driven by the gear mounted to the final electric motor to receive the combined rotational torque from the gears of the series of electric motors.

A drive mechanism includes a mount block extending along an axis and a plurality of electric motors supported by the mount block. The electric motors are arranged in series along the axis to define an initial electric motor, one or more intermediate electric motors, and a final electric motor. The drive mechanism also includes a gear mounted to each of the electric motors, and an output member driven by the gear mounted to the final electric motor to receive the combined rotational torque from the gears of the series of electric motors.

A vehicular propulsion system is described that uses a plurality of direct current (DC) motors operatively attached to a common drive shaft or shafts of an electric vehicle (EV) or boat. Each motor is powered separately by direct current from a battery cassette or trays swappably inserted into the chassis of the vehicle. The battery cassettes are secured in racks, with one or more individual battery cassettes connected to each of individual motors. The individual battery cassettes are sized to have a weight suitable so as to be readily swapped out as needed for recharging, maintenance or replacement, enabling vehicle range to be extended en route by exchanging depleted battery cassettes for new batteries whenever needed. DC motors may be selected to obtain efficiencies greater than obtainable with AC motors, but require no expensive inverter unit.

A vehicular propulsion system is described that uses a plurality of direct current (DC) motors operatively attached to a common drive shaft or shafts of an electric vehicle (EV) or boat. Each motor is powered separately by direct current from a battery cassette or trays swappably inserted into the chassis of the vehicle. The battery cassettes are secured in racks, with one or more individual battery cassettes connected to each of individual motors. The individual battery cassettes are sized to have a weight suitable so as to be readily swapped out as needed for recharging, maintenance or replacement, enabling vehicle range to be extended en route by exchanging depleted battery cassettes for new batteries whenever needed. DC motors may be selected to obtain efficiencies greater than obtainable with AC motors, but require no expensive inverter unit.

A vehicular propulsion system is described that uses a plurality of direct current (DC) motors operatively attached to a common drive shaft or shafts of an electric vehicle (EV) or boat. Each motor is powered separately by direct current from a battery cassette or trays swappably inserted into the chassis of the vehicle. The battery cassettes are secured in racks, with one or more individual battery cassettes connected to each of individual motors. The individual battery cassettes are sized to have a weight suitable so as to be readily swapped out as needed for recharging, maintenance or replacement, enabling vehicle range to be extended en route by exchanging depleted battery cassettes for new batteries whenever needed. Air cooling is enabled by use of the smaller battery cassettes and smaller motor assemblies. The torque of the smaller motors, operating on a common drive shaft, is additive according to a first embodiment in which a set of like motors are supplied. Variable ratio gearboxes are provided in the drivetrain so that motors can be directly coupled to the driven axle. By dividing the batteries among the motor loads and by combining the torques of several smaller motors at the drive shaft, improved range, serviceability and decreased cost are achieved. According to a second embodiment in which a set of unlike motors are supplied, unlike motors having torque curves optimized for different propulsion states are combined so as to improve mileage in a range of real world mixed driving conditions. Series-wound DC motors may be used in combination with brushless direct current (BLDC) motors (operated with Hall-effect positional feedback, encoders, resolvers, H-bridge MOSFETs, field-oriented control or pulse width modulation), shunt-excited motors, or compound-excited DC motors. With both like and unlike DC motors, magnetic coupling of surface, radial or embedded permanent magnets (PM) may be selected to obtain efficiencies greater than obtainable with AC motors, but require no expensive inverter unit.