Voltage mode driving

AN4144

10/28

DocID023491 Rev 3

The supply voltage of the systems limits the maximum phase current which is a function of

the motor speed. If the phase voltage which is needed to obtain the target current is greater

than the supply voltage, the phase current cannot reach the expected value (Figure 4).

Figure 4. Maximum output current limitation example

Parameter

Formula

Unit

Intersect speed

Starting slope

Final slope





 A

/V

=%





step

cycle

---------------

=

Hz





step

cycle

---------------



/H





step/s

=

/V

BUS

V

Hz

------- /

step

cycle

---------------



 =/ V

=% s/step



2

 L

m

+



/4

/V

BUS

V

Hz

------- /

step

cycle

---------------



 =/ V

=% s/step



^

D

s

s

s

s

D

Z

>

,

s,

AM12860V2