Datasheet

10. Start-up Procedure
When the motor is in stand-still, the phase of the permanent magnet flux vector cannot be detected with the used
algorithm. So an appropriate start-up procedure has to be applied.
The idea is to move the motor in feed-forward (with higher current than that required to win the load), till a speed at
which the estimation algorithm can work. Then the system can be aligned to the estimated phase, and the current can be
reduced to the strictly necessary quantity.
The following graph illustrates the strategy used (the suffix “
ref
” stands for reference, the suffix “
mea
” stands for
measured).
Start Up Process Graph
Referring to the graph, the start-up procedure (in case of three shunts current reading) is described below.
At the beginning t
0
, the system phase is unknown. No current is imposed to the motor; the system phase is arbitrarily
decided to be 
a
= 0. All the references: id
ref
, iq
ref
and speed
ref
are set to zero.
From the moment t
0
, while the iq
ref
and the speed
ref
are maintained to zero, id
ref
is increased with a ramp till the value
i
start
is reached at the moment t
1
.
The references are referred to an arbitrary (d
a
, q
a
) system based on the arbitrary phase 
a
. From this moment, the phase
estimation algorithm begins to be performed, and the estimated phase is 
est
.
The components of the current referred to the arbitrary (d
a
, q
a
) system are controlled to follow the references by the
current PI controllers, so they will be i
d
=i
start
and i
q
=0. If we refer the measurements to the estimated phase we would
obtain those which in the graph are called id
mea
and iq
mea
(referred to (d, q) estimated system); since the phase 
est
is still
not correctly estimated, id
mea
and iq
mea
have no physical meaning.
At t = t
1
, while iq
ref
is maintained to zero and id
ref
is maintained to its value i
start
, speed
ref
is increased with a ramp till the
value s
start
is reached at t = t
2
. The system phase 
a
(t) is obtained simply by integration of speed
ref
; in the meanwhile, the
phase estimation algorithm begins to align with the real system phase. Furthermore id
mea
and iq
mea
begin to be similar to
the real flux and torque components of the current.
t
1
t
0
t
2
t
3
t
i
start
s
start
id
0
iq
0
speed
ref
id
ref
iq
ref
id
mea
iq
mea