Direct Electrical Connection and Transmission Coupling for Multi-Motor Hybrid Drive System

1 . A system of electric power management for a hybrid vehicle comprising:

(a) an engine;

(b) a first inverter coupled to a second inverter;

(c) a first electric machine coupled to the engine and the first inverter;

(d) a first transmission coupled between the engine and the first electric machine, wherein the first transmission has a transmission speed ratio operable such that the first electric machine operating speed operates independent of an engine operating speed;

(e) a second electric machine coupled to the second inverter and a wheel axle of the vehicle;

(f) a high voltage battery coupled to both the first inverter and the second inverter;

(g) a switch box disposed between the first electric machine and the second electric machine, the switch box for selectively forming a direct electrical connection from the first electric machine to the second electric machine.

2 . The system of claim 1 , wherein the switch box includes a plurality of switches that allow for vehicle operation in a plurality of operating states.

3 . The system of claim 2 , wherein the switches are all open in a first operating state preventing electrical connection between the first electric machine and the second electric machine.

4 . The system of claim 2 , wherein the switches are all closed in a second operating state forming electrical connection between the first electric machine and the second electric machine.

5 . The system of claim 2 , wherein the switches are all closed in a third operating state forming electrical connection between the first electric machine and the second electric machine such that one of the electric machines can operate in reverse.

6 . The system of claim 1 , wherein the electric machine is operable to be a generator when spinning in a negative torque direction and a motor when spinning in an opposite positive torque direction.

7 . The system of claim 1 , wherein power can be transferred from the engine to the battery and from the battery to the engine and the wheel axle.

8 . The system of claim 1 , further comprising a mechanical engagement device disposed between the engine and the first electric machine adapted to selectively decouple the engine from the first electric machine.

9 . The system of claim 1 , wherein the mechanical engagement device is a clutch.

10 . The system of claim 1 , further comprising a third electric machine coupled to a second wheel axle of the vehicle and the switch box.

11 . The system of claim 10 , wherein the switch box allows for direct electrical connection between both the first and second electric machine and the third electric machine.

12 . The system of claim 10 , further comprising a mechanical engagement device disposed between the second wheel axle and the third electric machine adapted to selectively decouple the wheel axle from the third electric machine.

13 . The system of claim 10 , wherein the third electric machine is directly coupled to the second inverter and the second electric machine.

14 . The system of claim 10 , wherein the third electric machine is directly coupled to the first inverter and the first electric machine.

15 . The system of claim 10 , further comprising a second switch box disposed between the third electric machine and the first electric machine and first inverter adapted to allow for selectively connecting the third electric machine and the first electric machine and the first inverter.

16 . The system of claim 15 , wherein the second switch box is further disposed between the first electric machine and the first inverter.

17 . The system of claim 1 , wherein the switch box includes a plurality of switches having power-electronic and mechanical contactors.

18 . The system of claim 1 , wherein the first transmission includes a plurality of speed ratios allowing the engine and the first electric machine to operate at different speeds corresponding to the transmission speed ratio.

19 . The system of claim 1 , further comprising a second transmission coupled between a motor and the second electric machine, wherein the second transmission has a transmission speed ratio operable such that the second electric machine operating speed operates independent of a motor operating speed.

20 . A method of operating a hybrid vehicle comprising the steps of:

(a) coupling an engine to a first electric machine adapted to spin the electric machine to generate power;

(b) providing a transmission between the engine and the first electric machine;

(c) selecting a predetermined transmission speed ratio of engine speed to electric machine speed and operating the engine at a first speed and operating the first electric machine according to the transmission speed ratio;

(d) delivering power from the first electric machine to a switch box and to a first inverter, wherein the first inverter is coupled to a second inverter and a high voltage battery and the second inverter is further coupled to a second electric machine coupled to a wheel axle of the vehicle; and

(e) selectively forming a direct electrical connection between the first electric machine and the second electric machine.

21 . The system of claim 1 , the switch box for selectively forming a direct electrical connection between at least one of the first electrical machine and the first inverter and the second electrical machine and the second inverter.