Electric motor drives are being used increasingly for automotive water, oil, and fuel pumps, fans, and air conditioning systems. In conjunction with powerful control algorithms running on optimized microcontrollers, brushless DC (BLDC) motors offer very efficient solutions. For brushless motors, various control schemes, including field oriented control (FOC), are available.
Higher energy efficiency, better dynamics, and reduced running noise today constitute important design requirements for motor drives. For this reason, advanced control concepts, such as FOC, are also increasingly deployed in drives used for automotive electronics.
On the other hand, the effective implementation of these innovative control concepts call for optimized microcontroller architecture and tools that are easy to use. (Infineon provides a comprehensive portfolio of application kits with scalable reference designs for motor drives.) These kits include all the relevant hardware and software components for plug-and-play designs: Microcontrollers, power semiconductors in addition to passive components, plus documentation such as recommendations for hardware design. Furthermore, the application kits include the reference software and a complete real-time test environment.
Field oriented control
Using FOC, it is possible to boost the efficiency of an electric motor by up to 95%, with reduced power consumption, lower running noise, and better dynamics. This in turn improves the efficiency of the inverter, while allowing smaller power stages and motor dimensions with the same speed possible.
The FOC algorithm eliminates time and speed dependencies and, in doing so, permits direct and independent control of the magnetic flow and torque, via the mathematical conversion of the electric motor status into time-independent rotation coordinates. The corresponding mathematical formulas are known as Clarke and Park transformations. FOC can be used both for AC induction motors as well as for brushless DC motors.
For the complete article, which includes a comprehensive description of an automotive BLDC motor drive development kit, click here, courtesy of Automotive Designline Europe.
This is a very good design article. Since the simplest algorithm to control a BLDC motor is implemented using hall sensors , I would be interested to see a comparison of the hall sensor based control Vs FOC , in terms of the circuit complexity, software complexity , the advantages in terms of increase in efficiency, any advatanges related to motor protection, MOSFET protection etc.
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