TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.04 • 2018-Dec-11
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3 FOC Basics
This section gives a short introduction into some basics of Field Oriented Control (FOC) of electric motors.
3.1 Why FOC?
The Field Oriented Control (FOC), alternatively named Vector Control (VC), is a method for the most
energy-efficient way of turning an electric motor.
3.2 What is FOC?
The Field Oriented Control was independently developed by K. Hasse, TU Darmstadt, 1968, and by Felix
Blaschke, TU Braunschweig, 1973. The FOC is a current regulation scheme for electro motors that takes
the orientation of the magnetic field and the position of the rotor of the motor into account, regulating
the strength in such way that the motor gives that amount of torque that is requested as target torque.
The FOC maximizes active power and minimizes idle power - that finally results in power dissipation - by
intelligent closed-loop control illustrated by figure 1.
Figure 1: Illustration of the FOC basic principle by cartoon: Maximize active power and minimize idle power and
power dissipation by intelligent closed-loop control.
3.3 Why FOC as pure Hardware Solution?
The initial setup of the FOC is usually very time consuming and complex, although source code is freely
available for various processors. This is because the FOC has many degrees of freedom that all need to fit
together in a chain in order to work.
The hardware FOC as an existing standard building block drastically reduces the effort in system setup.
With that off the shelf building block, the starting point of FOC is the setup of the parameters for the FOC.
Setting up and implement the FOC itself and building and programming required interface blocks is no
longer necessary. The real parallel processing of hardware blocks de-couples the higher lever application
software from high speed real-time tasks and simplifies the development of application software. With the
TMC4671, the user is free to use its qualified CPU together with its qualified tool chain, freeing the user
from fighting with processer-specific challenges concerning interrupt handling and direct memory access.
There is no need for a dedicated tool chain to access the TMC4671 registers and to operate it - just SPI (or
UART) communication needs to be enabled for any given CPU.
The integration of the FOC as a SoC (System-on-Chip) drastically reduces the number of required compo-
nents and reduces the required PCB space. This is in contrast to classical FOC servos formed by motor
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