Board description
UM1036
18/48
Doc ID 18293 Rev 1
Overcurrent protection acts as soon as the voltage on the CIN pin rises above the internal
voltage reference (typical value
V
REF_INT
is 0.53 V). Considering the default value of the
OCP shunt resistor, it follows that the maximum allowed current is equal to:
Equation 1
With the default values this gives:
I
shunt_MAX
~ 20 A
Figure 10.
Overcurrent protection
Overcurrent protection can be disabled if the W2 jumper is set to the “B” position. This may
be necessary and is often useful when the user decides to make the brake operate by
turning on the three low-side switches. In fact, if the motor acts as a generator, it is
necessary to protect the hardware, preventing the bus voltage from exceeding a safety
threshold. In addition to dissipating the motor energy on a brake resistor, it's possible to
short the motor phases, preventing the motor current from flowing through the bulk
capacitors. Please note that if the OCP is disabled, the demonstration board is not protected
against any overcurrent event.
3.3.6
Current sensing amplifying network
The STEVAL-IHM028V1 motor control demonstration board can be configured to run in
various current reading configuration modes:
●
Three-shunt configuration - suitable for field oriented control (FOC)
●
Single-shunt configuration - suitable for FOC in a single-shunt configuration
●
Single-shunt - six-step configuration - suitable for scalar control.
I
sh un t MAX
0.53
R1
R2
R
+
×
2
R3
R1
R3
×
+
×
(
)
×
3.3
R1
R2
×
×
–
R
LS
R2
R3
×
×
-----------------------------------------------------------------------------------------------------------------------------------------------------
=
2,3
SENSE
RESISTOR
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6
2%&
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5
34')03+
#).
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2 2
2 2
2 2
3$
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6
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