AN3165 datasheet(14/31 Pages) STMICROELECTRONICS

14 / 31 page

STM32 dual motor field-oriented control

AN3165

14/31

Doc ID 17180 Rev 1

Dual motor driving is possible by way of two advanced PWM timers (TIM1 and TIM8) inside

the high density version of the STM32 microcontroller (STM32F103xC-D-E).

These two timers are kept synchronous using the master/slave feature of each timer

peripheral present in the microcontroller. The timers must be synchronized to ensure that

the current sampling occurs during the proper PWM period.

The single shunt solution implemented with the ST patented method expects two ADC

conversions for each motor to sample the phase currents. These two conversions are

normally performed within the first half of the PWM period or at most 3.5

μs after that time.

During each FOC execution rate (two PWM periods), the values of the phase currents are

sampled for one motor and the FOC algorithm related to that motor is executed. The

currents are therefore transformed with Clark and Park transformations, torque and flux PID

are executed and the voltage demand vector is computed using the reverse park

transformations and circle limitation.

The value of the three duty cycles to be applied to the inverter and the sampling points for

the current’s conversion are computed from the voltage demand vector, using the space

vector modulation. Depending on the selected firmware options, the state observer can be

used to estimate the rotor’s position and speed. The MTPA (flux weakening and feed

forward) can also be executed.

Figure 6.

Control strategy block diagram for STM32 dual FOC MC

AN3165 Datasheet(PDF) 14 Page - STMicroelectronics