Brushless DC motor control in just one day

April 07, 2011 // By Ralf Koedel, Alexander Schmidt
Electric motor drives are being used increasingly for water, oil and petrol pumps, fans and air conditioning systems in automotive applications. In conjunction with powerful control algorithms running on optimised microcontrollers, BLDC motors offer very efficient solutions. For brushless motors, various control schemes, including field oriented control (FOC), are available. The article explains how to implement of a complete motor control in just one day.

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 field oriented control, are also increasingly deployed in drives used for automotive electronics. On the other hand, the effective implementation of these innovative control concepts call for optimised 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&Play designs. These complete solutions comprise microcontrollers, power semiconductors in addition to passive components, plus the 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, whilst making 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. This is achieved 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.

Automotive BLDC Motor Drive Kit

Using the new development kit (Fig. 1), it is possible to quickly realise scalable solutions for the efficient control of 3-phase inverters with BLDC motors. To this end, the kit is based on two efficient automotive microcontrollers, the 8-bit MCU XC886 and the 16-bit MCU XC2236N, both of which support sensor-driven and sensor less control concepts. A new, highly integrated B6 bridge driver, the TLE7184F, is used as an interface to the

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