AMG-XB404 Datasheet, PDF (18/73 Pages) alpha microelectronics gmbh – Fully Integrated Single Motor Controller for Electrical Motors

AMG-XB404
Fully Integrated Single Motor Controller for Electrical Motors
N
ADC
1023
V (IDC)
OFFS
V (IAC)
OFFS
-I
0
PFC current range
+I
I
IN
DMCE current range
Figure 9: ADC current input characteristic
.
For the DC current channel VOFFS is set to nominally 445 mV. For the AC current channel VOFFS
is set to about 24 mV.
For improved noise rejection and accuracy the rectified AC voltage and the DC bus voltage values
are digitally low-pass filtered using IIR filters, the low-pass filtered values VACLP and VDCLP are
fed directly to the PFC controller. VDCLP is fed to the DMCE core and an inverter. The low-pass
filtered signal value for VACLP and VDCLP can be calculated as follows:
VACLP _N =₁₁₆₅⋅VACLP_{N −1}VAC _N VDCLP_N = ³³¹²â‹…VDCLP _{N −1}VDC _N
5.3.3. Triggering Analog Signal Acquisition
Sampling of the general purpose ADC channels 0 through 7 is triggered by writing the connected
flag within the register ADCREQ as one. Completion is indicated by reading the connected flag in
register ADCINT as one.
The rectified AC voltage and the DC bus voltage are sampled at the analog inputs VAC and VDC.
Sampling of these signals is triggered automatically every 1024 cycles of the system clock if
DMCE core is not reset. Sampling can also be triggered by setting the indirect request flag, IREQ,
via the IO expander (see section 5.2.20., page 12). The raw sample value can be read via the
ADC's registers (see table 6, p. 19), the low-pass filtered value using the respective DMCE and
PFC registers.
Sampling of DMCE current offset values is triggered when a zero-vector is set by the DMCE's
PWM unit. It is performed autonomously at the beginning of each PWM cycle when all low-side
switches of the PWM module are in ON-state, if the DMCE is not reset. Sampling can also be
triggered by setting the indirect request flag, IREQ, via the IO expander (see section 5.2.20., page
12). The raw sample value can be read using the ADC unit's registers as shown in table 7, p. 20,
the low-pass filtered value using the DMCE's register.
An on-chip temperature sensor provides a 0..1.8V analog signal that is sufficient for measurements
with an accuracy of 1.25 K/bit. The calibration setting of the temperature sensor is stored in the
EEPROM. Temperature sampling is triggered by setting the TREQ flag within the IO expander, see
section 5.2 p. 9. The TREQ flag will be reset to 0 when a temperature sample has been acquired.
AMG-XB404
Revision: A
2. Nov. 2012 © All rights reserved
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