AN1905 ST Microelectronics, Inc., AN1905 Datasheet - Page 55

• Manufacturer Part Number: AN1905
• Description: St7mc Three-phase BLDC Motor Control Software Library
• Manufacturer: ST Microelectronics, Inc.

7.2 CONTROL STRATEGY CONSIDERATIONS
7.2.1 Voltage versus current mode
The motor control peripheral of the ST7MC allows voltage and current control modes. Both
modes set the PWM duty cycle according to:
- Voltage mode: the values of the MCPUH/L registers allow direct configuration of the duty
cycle in accordance to the maximum allowed current thanks to the comparator cell (see
34).
- Current mode: the current threshold that will turn the PWM into off-state (see
Figure 34. PWM duty cycle behaviour in voltage mode
Figure 35. PWM duty cycle behaviour in current mode
MTC peripheral
ST7MC
Microcontroller
Channel V
PWM
ST7MC
Microcontroller
MTC peripheral
Channel V
PWM
100nF
MTC peripheral
33K
current
reference
Max current
PWM
reference
ST7MC THREE-PHASE BLDC MOTOR CONTROL SOFTWARE LIBRARY
W12
33K
100nF
Pot 1
MCCREF
MCCREF
clock
PWM freq.
channel U
Vdd
OAZ/MCCFI1
+
-
OAZ/MCCFI1
+
-
OPAMP
OPAMP
Set
R
R
set
T4
T4
A
T1
A
T1
HV
HV
Max current
reference
Motor
Voltage
current
reference
Motor
Voltage
clock
I
I
step time
T1-T4
step time
T1-T4
step time
step time
T1-T6
T1-T6
Figure
35).
Figure
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