bldc - BLDC and AC-servo control component
loadrt bldc cfg=qi6,aH
This component is designed as an interface between the most common forms of
three-phase motor feedback devices and the corresponding types of drive.
However, there is no requirement that the motor and drive should necessarily
be of inherently compatible types.
Each instance of the component is defined by a group of letters describing the
input and output types. A comma separates individual instances of the
component. For example
loadrt bldc cfg=qi6,aH.
Input type definitions are all lower-case.
n No motor feedback. This mode could be used to drive AC induction
motors, but is also potentially useful for creating free-running motor
simulators for drive testing.
h Hall sensor input. Brushless DC motors (electronically commutated
permanent magnet 3-phase motors) typically use a set of three Hall sensors to
measure the angular position of the rotor. A lower-case
h in the cfg
string indicates that these should be used.
a Absolute encoder input. (Also possibly used by some forms of Resolver
conversion hardware). The presence of this tag over-rides all other inputs.
Note that the component still requires to be be connected to the
rawcounts encoder pin to prevent loss of commutation on index-reset.
q Incremental (quadrature) encoder input. If this input is used then the
rotor will need to be homed before the motor can be run.
i Use the index of an incremental encoder as a home reference.
f Use a 4-bit Gray-scale patttern to determine rotor alignment. This
scheme is only used on the Fanuc "Red Cap" motors. This mode could
be used to control one of these motors using a non-Fanuc drive.
Output type descriptions are all upper-case.
Defaults The component will always calculate rotor angle, phase angle and
the absolute value of the input
value for interfacing with drives such
as the Mesa 8I20. It will also default to three individual, bipolar phase
output values if no other output type modifiers are used.
B Bit level outputs. Either 3 or 6 logic-level outputs indicating which
high or low gate drivers on an external drive should be used.
6 Create 6 rather than the default 3 outputs. In the case of numeric
value outputs these are separate positive and negative drive amplitudes. Both
have positive magnitude.
H Emulated Hall sensor output. This mode can be used to control a drive
which expects 3x Hall signals, or to convert between a motor with one hall
pattern and a drive which expects a different one.
F Emulated Fanuc Red Cap Gray-code encoder output. This mode might be
used to drive a non-Fanuc motor using a Fanuc drive intended for the
"Red-Cap" motors.
T Force Trapezoidal mode.
The component can control a drive in either Trapezoidal or Sinusoidal mode, but
will always default to sinusoidal if the input and output modes allow it. This
can be over-ridden by the
T tag. Sinusoidal commutation is
significantly smoother (trapezoidal commutation induces 13% torque ripple).
To use an encoder for commutation a reference 0-degrees point must be found. The
component uses the convention that motor zero is the point that an unloaded
motor aligns to with a positive voltage on the A (or U) terminal and the B
& C (or V and W) terminals connected together and to -ve voltage. There
will be two such positions on a 4-pole motor, 3 on a 6-pole and so on. They
are all functionally equivalent as far as driving the motor is concerned. If
the motor has Hall sensors then the motor can be started in trapezoidal
commutation mode, and will switch to sinusoidal commutation when an alignment
is found. If the mode is
qh then the first Hall state-transition will
be used. If the mode is
qhi then the encoder index will be used. This
gives a more accurate homing position if the distance in encoder counts
between motor zero and encoder index is known. To force homing to the Hall
edges instead simply omit the
i.
Motors without Hall sensors may be homed in synchronous/direct mode. The better
of these options is to home to the encoder zero using the
iq config
parameter. When the
init pin goes high the motor will rotate (in a
direction determined by the
rev pin) until the encoder indicates an
index-latch (the servo thread runs too slowly to rely on detecting an encoder
index directly). If there is no encoder index or its location relative to
motor zero can not be found, then an alternative is to use
magnetic
homing using the
q config. In this mode the motor will go through an
alignment sequence ending at motor zero when the init pin goes high It will
then set the final position as motor zero. Unfortunately the motor is rather
springy in this mode and so alignment is likely to be fairly sensitive
to load.
-
bldc.N (requires a floating-point
thread)
-
- bldc.N.hall1 bit in [if personality &
0x01]
- Hall sensor signal 1
- bldc.N.hall2 bit in [if personality &
0x01]
- Hall sensor signal 2
- bldc.N.hall3 bit in [if personality &
0x01]
- Hall sensor signal 3
- bldc.N.hall-error bit out [if personality
& 0x01]
- Indicates that the selected hall pattern gives inconsistent
rotor position data. This can be due to the pattern being wrong for the
motor, or one or more sensors being unconnected or broken. A consistent
pattern is not neceesarily valid, but an inconsistent one can never be
valid.
- bldc.N.C1 bit in [if ( personality &
0x10 )]
- Fanuc Gray-code bit 0 input
- bldc.N.C2 bit in [if ( personality &
0x10 )]
- Fanuc Gray-code bit 1 input
- bldc.N.C4 bit in [if ( personality &
0x10 )]
- Fanuc Gray-code bit 2 input
- bldc.N.C8 bit in [if ( personality &
0x10 )]
- Fanuc Gray-code bit 3 input
- bldc.N.value float in
- PWM master amplitude input
- bldc.N.lead-angle float in [if personality
& 0x06] (default: 90)
- The phase lead between the electrical vector and the rotor
position in degrees
- bldc.N.rev bit in
- Set this pin true to reverse the motor. Negative PWM
amplitudes will alsoreverse the motor and there will generally be a Hall
pattern that runs the motor in each direction too.
- bldc.N.frequency float in [if (
personality & 0x0F ) == 0]
- Frequency input for motors with no feedback at all, or
those with only an index (which is ignored)
- bldc.N.initvalue float in [if personality
& 0x04] (default: 0.2)
- The current to be used for the homing sequence in
applications where an incremental encoder is used with no hall-sensor
feedback
- bldc.N.rawcounts s32 in [if personality
& 0x06] (default: 0)
- Encoder counts input. This must be linked to the encoder
rawcounts pin or encoder index resets will cause the motor commutation to
fail.
- bldc.N.index-enable bit io [if personality
& 0x08]
- This pin should be connected to the associated encoder
index-enable pin to zero the encoder when it passes index. This is only
used indicate to the bldc control component that an index has been
seen.
- bldc.N.init bit in [if ( personality &
0x05 ) == 4]
- A rising edge on this pin starts the motor alignment
sequence. This pinshould be connected in such a way that the motors
re-align any time that encoder monitoring has been interrupted. Typically
this will only be at machine power-off. The alignment process involves
powering the motor phases in such a way as to put the motor in a known
position. The encoder counts are then stored in the offset
parameter. The alignment process will tend to cause a following error if
it is triggered while the axis is enabled, so should be set before the
matching axis.N.enable pin. The complementary init-done pin can be
used to handle the required sequencing.
Both pins can be ignored if the encoder offset is known explicitly, such as
is the case with an absolute encoder. In that case the offset
parameter can be set directly in the HAL file.
- bldc.N.init-done bit out [if ( personality
& 0x05 ) == 4] (default: 0)
- Indicates homing sequence complete.
- bldc.N.A-value float out [if ( personality
& 0xF00 ) == 0]
- Output amplitude for phase A
- bldc.N.B-value float out [if ( personality
& 0xF00 ) == 0]
- Output amplitude for phase B
- bldc.N.C-value float out [if ( personality
& 0xF00 ) == 0]
- Output amplitude for phase C
- bldc.N.A-on bit out [if ( personality
& 0xF00 ) == 0x100]
- Output bit for phase A
- bldc.N.B-on bit out [if ( personality
& 0xF00 ) == 0x100]
- Output bit for phase B
- bldc.N.C-on bit out [if ( personality
& 0xF00 ) == 0x100]
- Output bit for phase C
- bldc.N.A-high float out [if ( personality
& 0xF00 ) == 0x200]
- High-side driver for phase A
- bldc.N.B-high float out [if ( personality
& 0xF00 ) == 0x200]
- High-side driver for phase B
- bldc.N.C-high float out [if ( personality
& 0xF00 ) == 0x200]
- High-side driver for phase C
- bldc.N.A-low float out [if ( personality
& 0xF00 ) == 0x200]
- Low-side driver for phase A
- bldc.N.B-low float out [if ( personality
& 0xF00 ) == 0x200]
- Low-side driver for phase B
- bldc.N.C-low float out [if ( personality
& 0xF00 ) == 0x200]
- Low-side driver for phase C
- bldc.N.A-high-on bit out [if ( personality
& 0xF00 ) == 0x300]
- High-side driver for phase A
- bldc.N.B-high-on bit out [if ( personality
& 0xF00 ) == 0x300]
- High-side driver for phase B
- bldc.N.C-high-on bit out [if ( personality
& 0xF00 ) == 0x300]
- High-side driver for phase C
- bldc.N.A-low-on bit out [if ( personality
& 0xF00 ) == 0x300]
- Low-side driver for phase A
- bldc.N.B-low-on bit out [if ( personality
& 0xF00 ) == 0x300]
- Low-side driver for phase B
- bldc.N.C-low-on bit out [if ( personality
& 0xF00 ) == 0x300]
- Low-side driver for phase C
- bldc.N.hall1-out bit out [if ( personality
& 0x400 )]
- Hall 1 output
- bldc.N.hall2-out bit out [if ( personality
& 0x400 )]
- Hall 2 output
- bldc.N.hall3-out bit out [if ( personality
& 0x400 )]
- Hall 3 output
- bldc.N.C1-out bit out [if ( personality
& 0x800 )]
- Fanuc Gray-code bit 0 output
- bldc.N.C2-out bit out [if ( personality
& 0x800 )]
- Fanuc Gray-code bit 1 output
- bldc.N.C4-out bit out [if ( personality
& 0x800 )]
- Fanuc Gray-code bit 2 output
- bldc.N.C8-out bit out [if ( personality
& 0x800 )]
- Fanuc Gray-code bit 3 output
- bldc.N.phase-angle float out (default:
0)
- Phase angle including lead/lag angle after encoder zeroing,
etc. Useful for angle/current drives. This value has a range of 0 to 1 and
measures electrical revolutions. It will have two zeros for a 4 pole
motor, three for a 6-pole, etc.
- bldc.N.rotor-angle float out (default:
0)
- Rotor angle after encoder zeroing etc. Useful for
angle/current drives which add their own phase offset such as the 8I20.
This value has a range of 0 to 1 and measures electrical revolutions. It
will have two zeros for a 4 pole motor, three for a 6-pole, etc.
- bldc.N.out float out
- Current output, including the effect of the dir pin and the
alignment sequence.
- bldc.N.out-dir bit out
- Direction output, high if /fBvalue/fR is negative XOR
/fBrev/fR is true.
- bldc.N.out-abs float out
- Absolute value of the input value
- bldc.N.in-type s32 r (default:
-1)
- state machine output, will probably hide after debug
- bldc.N.out-type s32 r (default:
-1)
- state machine output, will probably hide after debug
- bldc.N.scale s32 rw [if personality &
0x06] (default: 512)
- The number of encoder counts per rotor revolution.
- bldc.N.poles s32 rw [if personality &
0x06] (default: 4)
- The number of motor poles. The encoder scale will be
divided by this value to determine the number of encoder counts per
electrical revolution.
- bldc.N.encoder-offset s32 rw [if
personality & 0x0A] (default: 0)
- The offset, in encoder counts, between the motor electrical
zero and the encoder zero modulo the number of counts per electrical
revolution
- bldc.N.offset-measured s32 r [if
personality & 0x04] (default: 0)
- The encoder offset measured by the homing sequence (in
certain modes)
- bldc.N.drive-offset float rw (default:
0)
- The angle, in degrees, applied to the commanded angle by
the drive in degrees. This value is only used during the homing sequence
of drives with incremental encoder feedback. It is used to back-calculate
from commanded angle to actual phase angle. It is only relevant to drives
which expect rotor-angle input rather than phase-angle demand. Should be 0
for most drives.
- bldc.N.output-pattern u32 rw [if
personality & 0x400] (default: 25)
- Commutation pattern to be output in Hall Signal translation
mode. See the description of /fBpattern/fR for details.
- bldc.N.pattern u32 rw [if personality
& 0x01] (default: 25)
- Commutation pattern to use, from 0 to 47. Default is type
25. Every plausible combination is included. The table shows the
excitation pattern along the top, and the pattern code on the left hand
side. The table entries are the hall patterns in H1, H2, H3 order. Common
patterns are: 0 (30 degree commutation) and 26, its reverse. 17 (120
degree). 18 (alternate 60 degree). 21 (300 degree, Bodine). 22 (240
degree). 25 (60 degree commutation).
Note that a number of incorrect commutations will have non-zero net torque
which might look as if they work, but don't really.
If your motor lacks documentation it might be worth trying every pattern.
| Phases, Source - Sink |
|
|
|
|
|
|
|
| pat |
B-A |
C-A |
C-B |
A-B |
A-C |
B-C |
|
| 0 |
000 |
001 |
011 |
111 |
110 |
100 |
| 1 |
001 |
000 |
010 |
110 |
111 |
101 |
| 2 |
000 |
010 |
011 |
111 |
101 |
100 |
| 3 |
001 |
011 |
010 |
110 |
100 |
101 |
| 4 |
010 |
011 |
001 |
101 |
100 |
110 |
| 5 |
011 |
010 |
000 |
100 |
101 |
111 |
| 6 |
010 |
000 |
001 |
101 |
111 |
110 |
| 7 |
011 |
001 |
000 |
100 |
110 |
111 |
| 8 |
000 |
001 |
101 |
111 |
110 |
010 |
| 9 |
001 |
000 |
100 |
110 |
111 |
011 |
| 10 |
000 |
010 |
110 |
111 |
101 |
001 |
| 11 |
001 |
011 |
111 |
110 |
100 |
000 |
| 12 |
010 |
011 |
111 |
101 |
100 |
000 |
| 13 |
011 |
010 |
110 |
100 |
101 |
001 |
| 14 |
010 |
000 |
100 |
101 |
111 |
011 |
| 15 |
011 |
001 |
101 |
100 |
110 |
010 |
| 16 |
000 |
100 |
101 |
111 |
011 |
010 |
| 17 |
001 |
101 |
100 |
110 |
010 |
011 |
| 18 |
000 |
100 |
110 |
111 |
011 |
001 |
| 19 |
001 |
101 |
111 |
110 |
010 |
000 |
| 20 |
010 |
110 |
111 |
101 |
001 |
000 |
| 21 |
011 |
111 |
110 |
100 |
000 |
001 |
| 22 |
010 |
110 |
100 |
101 |
001 |
011 |
| 23 |
011 |
111 |
101 |
100 |
000 |
010 |
| 24 |
100 |
101 |
111 |
011 |
010 |
000 |
| 25 |
101 |
100 |
110 |
010 |
011 |
001 |
| 26 |
100 |
110 |
111 |
011 |
001 |
000 |
| 27 |
101 |
111 |
110 |
010 |
000 |
001 |
| 28 |
110 |
111 |
101 |
001 |
000 |
010 |
| 29 |
111 |
110 |
100 |
000 |
001 |
011 |
| 30 |
110 |
100 |
101 |
001 |
011 |
010 |
| 31 |
111 |
101 |
100 |
000 |
010 |
011 |
| 32 |
100 |
101 |
001 |
011 |
010 |
110 |
| 33 |
101 |
100 |
000 |
010 |
011 |
111 |
| 34 |
100 |
110 |
010 |
011 |
001 |
101 |
| 35 |
101 |
111 |
011 |
010 |
000 |
100 |
| 36 |
110 |
111 |
011 |
001 |
000 |
100 |
| 37 |
111 |
110 |
010 |
000 |
001 |
101 |
| 38 |
110 |
100 |
000 |
001 |
011 |
111 |
| 39 |
111 |
101 |
001 |
000 |
010 |
110 |
| 40 |
100 |
000 |
001 |
011 |
111 |
110 |
| 41 |
101 |
001 |
000 |
010 |
110 |
111 |
| 42 |
100 |
000 |
010 |
011 |
111 |
101 |
| 43 |
101 |
001 |
011 |
010 |
110 |
100 |
| 44 |
110 |
010 |
011 |
001 |
101 |
100 |
| 45 |
111 |
011 |
010 |
000 |
100 |
101 |
| 46 |
110 |
010 |
000 |
001 |
101 |
111 |
| 47 |
111 |
011 |
001 |
000 |
100 |
110 |
Andy Pugh
GPL