Product specifications

R01AN0168ED0101 Rev. 01.01 48
Application Note
Chapter 7 Performing Zero Point Detection
The following chapters are referring to the steps indicated within Figure 7-10
“Executing a ZPD Table” on page 47
.
(1) Rotating the Anchor to 0°
Assuming that we are in Quadrant 0, the anchor is set to a horizontal direction
by applying 100% PWM for horizontal and 0% PWM for vertical.
(2) Rotating the Anchor to 270° (approaching the Measurement Position)
A right turn of -90° is performed by applying 100% vertical PWM and 0%
horizontal PWM in
Quadrant 3. By applying 0% PWM, the energy of the
horizontal coil is recirculated, so that its self-induction pulse is reduced.
(3) Preparing the ZPD Measurement
Using Direct I/O Control, the vertical coil is kept full powered, while the
horizontal coil is disconnected. This phase is used as a delay, to approach the
time-window of the ZPD induction within the horizontal coil. During this phase,
the anchor is still moving towards the 270° position.
(a) Optional additional Delay
Depending on the clocking of ISM and the setting of GUD, additional delay
steps can be required to wait on the correct time-window position. This can be
realized by simply repeating the phase
3 “Preparing the ZPD Measurement”.
(4) ZPD Measurement Phase
By activating ZMT, the ZPD measurement is started. At the same time, the
horizontal coil is pulled to ground on one side, while its other side is attached to
the analogue measurement input, which is selected by the
ZIS setting. The
vertical coil remains powered, in order to complete the anchor rotation.
Blanking Delay can be used to add further delay with higher precision to the
time-window.
The ZPD measurement is performed using the defined
Measurement Cycles.
In our example, the level is reached that indicates that the zero point was not
yet reached.
As a consequence, as
ZSS is set, the horizontal coil is recirculated, as soon as
the detection of non-zero-point has happened.
(a) Optional additional Delay within Measurement
By adding identical steps of phase 4 “ZPD Measurement Phase”, the
measurement phase can be extended. If the measurement phase ends by a
step with
ZMT cleared, the decision of stopping the execution is taken.
(5) Delay of ZPD Measurement Completion
This optional delay phase shall achieve that the anchor has finally reached the
270° position.
(6) Rotating the Anchor to 180°
By using PWM, the anchor is now rotated to the 180° position, which is in
Quadrant 2. At this point, alternatively, a new measurement can already be
prepared by continuing with an adjusted phase
3 “Preparing the ZPD
Measurement”.
Note Following further steps must achieve, that the anchor completes at least one
full turn within one pass of the ZPD table. Like this, the motor keeps on turning,
until the ZPD table execution is aborted in case the ZP is reached.