Methods and systems for a transmission. In one example, the transmission system includes a first electric motor that is rotationally coupled to a first shaft with a first gear idly mounted thereto and a second electric motor that is rotationally coupled to a second shaft with a second gear idly mounted thereto. The transmission system further includes an intermediate shaft with a third gear fixedly coupled thereto, a first clutch configured to selectively rotationally couple the first gear and the first shaft, and a second clutch configured to selectively rotationally couple the second gear and the second shaft.

Disclosed in the present invention is a dual-structured power output apparatus of an electric drive and power system that provides a means for outputting both mechanical power and electrical power. It comprises dual motor/generators having two stator assemblies, two rotor assemblies and a power transmission unit all integrated into a single housing for easy mounting. The power transmission unit is disposed adjacent to the two motor/generators and coupled on both ends to rotating shafts mechanically linked to the rotor assemblies such that they are rotatable relative to each other. It function is to change the rotational speed and torque of at least one of the rotors in order to reduce weight and physical size of the apparatus, and thus significantly improving the power density and capability. The structure of the apparatus is well-suited to improve the performance and fuel efficiency of the prior art hybrid powertrain.

When at least one of motor generators is not under normal control and where the MG1 temperature is less than an upper limit value, an ECU is configured to perform an inverter-less running control. In the inverter-less running control, an inverter is brought into a gate shutoff state and an engine is driven to cause the motor generator to generate a counter-electromotive voltage which consequently produces a counter-electromotive torque. During the inverter-less running control, the ECU makes a voltage difference between the counter-electromotive voltage and the voltage of a power line connecting a converter and an inverter when the MG1 temperature is equal to or greater than a predetermined value smaller than the voltage difference when the MG1 temperature is less than the predetermined value.

Disclosed in the present invention is a dual-structured power output apparatus of an electric drive and power system that provides a means for outputting both mechanical power and electrical power. It comprises dual motor/generators having two stator assemblies, two rotor assemblies and a power transmission unit all integrated into a single housing for easy mounting. The power transmission unit is disposed adjacent to the two motor/generators and coupled on both ends to rotating shafts mechanically linked to the rotor assemblies such that they are rotatable relative to each other. It function is to change the rotational speed and torque of at least one of the rotors in order to reduce weight and physical size of the apparatus, and thus significantly improving the power density and capability. The structure of the apparatus is well-suited to improve the performance and fuel efficiency of the prior art hybrid powertrain.