Integrated Modular Motor Drives

Thermally integrated power electronics in electrical machines

Integrated modular motor drive: what and why?

Emerging power electronic technologies are characterized by a high energy-efficiency, a high power density and a high operational temperature. Therefore, they resulted in the transition of a physically split motor and a power electronic inverter to a more compact system with higher power density in which the power electronic inverter is integrated in the motor. In literature, these systems are called integrated motor drives (IMDs). In such an integrated system, the electrical machine and power electronics share the same housing.

Due to the redundancy of an individual housing, the volume of these IMDs can be strongly reduced. In addition, cables between the machine and the power electronics converter can be omitted, which has a beneficial effect on the overall system weight, reduces the risk of emitted EMI and avoids overvoltage due to transmission line effects by the PWM voltage waveforms.

A major step in this integration process is the discretization of both the motor and the power electronics converter into modules. In this manner, an integrated modular motor drive (IMMD) is created. In this approach, the stator of the electric machine is made up of a number of pole drive units. This modular approach simplifies the construction of the drive system, allows to control of the winding currents individually, and is perfectly suited for special control and fault tolerant techniques.

The main disadvantage of this integration is that the power electronics components are exposed to the high temperatures, vibration and electromagnetic fields inherently present in electrical machines.

Certainly, the high operating temperature of the motor in relation to that of traditional power electronics components is referred to in the literature as one of the main points that inhibits the commercialization of these integrated systems.

Research topics:

  • Integrated cooling
  • SiC/GaN FET based designs
  • DC-link (capacitance) optimization