Power system

A method of operating a mobile machine, the mobile machine having a prime mover, an electric machine, a multiple-ratio transmission with a rotary input member and a rotary output member, one or more propulsion devices drivingly connected to the rotary output member, and a coupler connected between the rotary input member and each of the prime mover and the electric machine, the method comprising:

• in at least some circumstances, controlling the operating speeds of the prime mover and the electric machine independently of the operating speed of the rotary input member while the coupler accommodates any incompatibilities between the operating speed of the rotary input member and the operating speeds of the prime mover and the electric machine by slipping;
• selectively causing the coupler to slip while transmitting power between the rotary input member and at least one of the prime mover and the electric machine;
• when the mobile machine is in motion, changing the drive ratio of the multiple-ratio transmission from a first drive ratio to a second drive ratio;
• and
• in concert with changing the drive ratio of the multiple-ratio transmission, operating the electric machine to adjust an operating speed of the prime mover toward a synchronous speed for the second drive ratio.

A power system, comprising:

• a prime mover;
• an electric machine;
• a multiple-ratio transmission having a rotary input member and a rotary output member;
• a variable-slip coupler connected between the prime mover and the rotary input member, the variable-slip coupler also being connected between the electric machine and the rotary input member;
• and
• power-system controls operable to
• selectively cause the variable-slip coupler to slip while transmitting power between the rotary input member of the multiple-ratio transmission and at least one of the prime mover and the electric machine, and
• in concert with a change in a drive ratio of the multiple-ratio transmission from a first drive ratio to a second drive ratio, operate the electric machine to adjust an operating speed of the prime mover toward a synchronous speed for the second drive ratio.