UM0324 datasheet(28/105 Pages) STMICROELECTRONICS

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Running the demo program

UM0324

28/105

Moving the joystick left or right in these circumstances allows changing the context into the

second menu where it is possible to modify both the torque and flux reference.

Finally press either the KEY button or the joystick to start the motor (main state machine will

move from IDLE to START state).

The ramp up strategy is illustrated in Figure 13. Basically, the applied torque reference

reaches the final Iq value set with the joystick in the time that you configure in the

STARTUP_RAMP_DURATION

parameter (defined in MC_Control_Param.h) following a

linear ramp.

After STARTUP_RAMP_DURATION, if valid information from the speed sensor (tachometer or

encoder) is detected, the torque reference becomes adjustable on the fly from the joystick.

On the contrary, if no valid information from the speed sensor is detected, for example

because a problem occurred with speed sensor connections or because the load torque is

higher then the value that you set, then the final torque reference is kept constant until

STARTUP_TIMEOUT

Finally, when no valid speed information comes from the motor and STARTUP_TIMEOUT is

elapsed, the main state machine goes into FAULT state for two seconds and the error

message ‘Start-up failed’ is displayed on the LCD. In this case, it is strongly advised to

check speed sensor feedback connections first and then, if necessary, to increase the final

ramp torque reference in case the load torque is too high.

Caution:

In open loop operation, a constant torque reference is produced. Depending on the load

torque applied, this could lead to constant acceleration of the motor, making the speed rise

up to the motor’s physical limits.

Figure 13.

Open loop start-up strategy

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