There are applications that require multiple electric machine drives, such as electric or hybrid electric vehicles, where there is a main traction motor and one or more accessory motors or generators. To control the speed or power of these multiple motors or generators independently, each motor or generator requires an inverter. The use of an inverter enables the motor or generator to run in either a motoring mode or a generating mode. A consequence of this design is that each vehicle requires a number of inverters and inverter controllers, plus the engine volume to house them all.
To improve options for motor design, an integrated inverter control was developed for directing multiple inverters with a single processer. This invention reduces the number of components required in an electric engine, lowering the total component cost. It also supports the design of smaller engines.
The integrated inverter control permits each inverter to share one or more of the following: a common DC bus, a DC bus filtering capacitor, a gate drive circuit, a process control circuit, voltage sensors, current sensors, speed sensors, or position sensors. With a proper control algorithm, the motors/generators can be run in either a motoring mode (providing power to the motor shaft) or in a generating mode (power is transferred from the motor shaft to the inverter direct current source). The invention can be used in synchronous machines, induction machines, or permanent magnet machines.
The invention provides advantages of lower cost and a smaller volume for drive systems in specific applications such as the electric or hybrid vehicle. In this application, one machine serves as a main traction machine while other machines are used to power accessory devices on the vehicle.