Independent clutch and power device control of a multi-mode electro-mechanical infinitely variable transmission operating without electric energy storage device
A method and system for operating a multi-mode electro-mechanical infinitely variable transmission (EMIVT) that is coupled to an engine and includes two electric machines is described. In one example, operating modes of the two electric machines are controlled without regard to vehicle speed and system conditions that are external to the two electric machines.
1 . A driveline, comprising:
a transmission including a first electric machine, a second electric machine, a planetary gear set, and a DC voltage bus;
an internal combustion engine coupled to the transmission; and
a controller including executable instructions stored in non-transitory memory that cause the controller to operate the first electric machine in a first electric machine voltage control mode and the second electric machine in a second electric machine torque control mode in response to a speed of the second electric machine being less than a second threshold speed for voltage regulation of the DC voltage bus and a speed of the first electric machine being greater than a first threshold speed for voltage regulation of the DC voltage bus while operating the internal combustion engine in an engine torque control mode, and wherein the engine is operated in only the engine torque control mode and not in speed control mode for all vehicle speeds and all driver demand torque requests.
2 . The driveline of claim 1 , further comprising additional instruction to operate the second electric machine in a second electric machine voltage control mode and the first electric machine in a first electric machine torque control mode in response to the speed of the second electric machine being greater than the second threshold speed for voltage regulation of the DC voltage bus and the speed of the first electric machine being less than the first threshold speed for voltage regulation of the DC voltage bus while operating the internal combustion engine in the engine torque control mode, wherein the engine torque is adjusted via an engine actuator including one or more of a throttle, a cam phase adjuster, a fuel injector, and a turbocharger waste gate during the engine torque control mode.
3 . The driveline of claim 2 , further comprising additional instruction to operate the first electric machine in the first electric machine voltage control mode and the second electric machine in the second electric machine torque control mode in further response to the second electric machine being power limited for voltage regulation of the DC voltage bus.
4 . The driveline of claim 3 , further comprising additional instruction to operate the second electric machine in the second electric machine voltage control mode and the first electric machine in the first electric machine torque control mode in further response to the first electric machine being power limited for voltage regulation of the DC voltage bus.
5 . The driveline of claim 1 , further comprising a vehicle that includes the driveline, and where the internal combustion engine is operated in the engine torque control mode while the vehicle is operated at zero speed and at all times when the vehicle is traveling at speeds above zero speed, wherein the engine torque control mode comprises commanding the engine to follow a requested torque.
6 . The driveline of claim 1 , where the controller is a driveline controller, and wherein the engine is operated in the engine torque control mode in response to an electric energy storage device not being present or coupled to the DC bus.
7 . The driveline of claim 6 , further comprising and engine controller configured to adjust one or more actuators such that the internal combustion engine generates a torque requested via the driveline controller, and wherein the engine speed increases and decreases during the engine torque control mode.