UM-YROTATE-IT-RX62T datasheet(30/54 Pages) RENESAS

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RX62T

YROTATE-IT-RX62T Motor Control Kit

UM-YROTATE-IT-RX62T Rev.1.00

Page 30 of 51

Jan 15, 2014

15. 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).

Referring to the graph, the startup procedure (in case of three shunts current reading) is described below.

a) At the beginning t0, 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: idref, iqref and speedref are set to zero.

b) From the moment t0, while the iqref and the speedref are maintained to zero, idref is increased with a ramp till

the value istart is reached at the moment t1.

The references are referred to an arbitrary (da, qa) system based on the arbitrary phase

a. From this moment, the

phase estimation algorithm begins to be performed, and the estimated phase

est is used to calculate the

components of the measured current, referred to the (d, q) system based on the estimated phase, idmea and iqmea.

The components of the current referred to the arbitrary (da, qa) system are controlled to follow the references by the

current PI controllers. On the other hand, since the phase

est is still not correctly estimated, idmea and iqmea have no

physical meaning. Even if they are not shown in the graph, the applied voltages are subjected to the same treatment

(vdmea and vqmea are calculated in the algorithm).

c) At t = t1, while iqref is maintained to zero and idref is maintained to its value istart, speedref is increased with a

ramp till the value sstart is reached at the t = t2. The system phase

a(t) is obtained simply by integration of

speedref; in the meanwhile, the phase estimation algorithm begins to align with the real system phase.

istart

sstart

id0

iq0

speedref

idref

iqref

idmea

iqmea

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