UM1756 datasheet(22/49 Pages) STMICROELECTRONICS

22 / 49 page

Device configuration

UM1756

22/49

DocID026263 Rev 2

4.2

Voltage mode driving (EVAL6480H-DISC)

The configuration parameters of the voltage mode driving can be obtained through the

BEMF compensation tool embedded into the SPIN family software.

A wrong setup of these parameters could cause several issues, in particular:



The phase current decreases with the speed and the motor is stall.



The wrong voltage is applied to the motor and the system is very noisy.



The phase current reaches the overcurrent limit.

The BEMF compensation form uses the application parameters as inputs in order to

evaluate the proper device setup.

The required inputs are:



Supply voltage.



Target phase current (r.m.s. value) at different motion conditions (acceleration,

deceleration, constant speed and holding).



Target operating speed (maximum speed).



Motor characteristics.

The motor characteristics are: the electrical constant (Ke), phase inductance and

resistance. The inductance and the resistance of the phase are given in the motor

datasheet. The Ke is rarely given in the specification and must be measured.

In the help section of the SPIN family software, a step by step procedure is explained. The

same procedure can also be found in the application note AN4144: “Voltage mode control

operation and parameter optimization” on www.st.com.

Click on the “evaluate” button to get the suggested setup for the voltage mode driving. Then

click on the “write” button to copy the data into the registers of the device.

Figure 15. B.E.M.F compensation - SPIN family evaluation software

UM1756 Datasheet(PDF) 22 Page - STMicroelectronics