# Emerging Technologies for Advanced Power Electronics and Machine Design in Electric Drives
## 4 Integration of Power Electronics and Electric Machines
### Trends in Integration of the Control Stage  
In addition to the improvements in the power stage, decisive improvements are also being made in the control stage. This includes stand-alone or integrated three-phase gate drivers, motor control application-specific integrated circuits (ASICs) with integrated current measurement and control, and motor control-oriented microcontroller units (MCUs) with pulse-width modulation (PWM) modules for streamlined integration. These MCUs have features such as dead-time generation, a PWM signal chopper that can generate high-frequency signals routed through galvanic isolation, and other advanced functionalities. In addition, there is a growing trend towards highly integrated solutions that include all of the above components [163; 164]. These integrated solutions offer a comprehensive approach to motor control.  
As far as software is concerned, many manufacturers of motor control-oriented microcontroller units (MCUs) now offer special software libraries. These libraries include algorithms for current control, field-oriented control (FOC), various space vector modulation (SVM) algorithms [173; 174], and sensorless control. These software resources aim to simplify and accelerate the development of motor control software and provide developers with a solid foundation for efficient implementation.  
For multiphase drives and/or drives that use multilevel/multi-leg converters, the situation is quite different, as these designs are usually customized or still in the research phase. Although there are some solutions for most common three-level converters at the power stage level [175; 176], the solutions at the signal/control electronics and software level are practically non-existent. There are no off-the-shelf ASICs for multilevel, multiphase converters, and there are no widely available libraries for multilevel, multiphase PWM generation in motor control/power conversion. This could be due to both low demand and the many degrees of freedom available, as power stage modulation (PWM signals) for multilevel, multiphase drives can be optimized for different objectives and there are currently no clear optimal solutions compared to the space vector modulation in B6 converters. To the best knowledge of the authors, there are no libraries/examples of current control or FOC control algorithms for multiphase drives. Moreover, since the multilevel/multiphase converters require numerous PWM signals to control the increased number of power switches, there are no integrated MCU solutions for inverters with a high number of power switches (higher number of voltage levels). Therefore, most of the multilevel/multiphase solutions, used in practice and not for research or development purposes, are based on field programmable gate arrays (FPGAs). FPGA-based solutions offer much more computational power and can be much faster, but these advantages only come to play at higher switching frequencies. At lower switching frequencies, FPGAs are usually used to generate all the required PWM signals. The major disadvantage of FPGA solutions compared to MCU-based solutions is the significantly higher integration complexity [177]. While MCUs already have integrated PWM, ADC, RAM, and FLASH, FPGAs have all these components externally. This requires significantly more effort in the design of the PCB (high-speed DRAM/FLASH interface) and in the design of the software (customized design of ADC sequencer, customized PWM implementation, etc.).  
Although many solutions [175; 176; 178; 179] already exist for the design of multi-level/multiphase machines and power stages, more effort needs to be put into the control electronics to enable the market to offer cost-effective solutions for such drives.