User Manual

Motor Deactivation in Case of Output Stage Hardware Failure
Advanced Digital Motor Controller User Manual 35
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FIGURE 2-1. MOSFET Failures resulting in no motor activation
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FIGURE 2-2. MOSFET Failures resulting in battery short circuit and no motor activation
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FIGURE 2-3. MOSFET Failure resulting in motor activation
Two failure conditions (15 and 16) will result in the motor spinning out of control re-
gardless of whether the controller is on or off. While these failure conditions are rare,
users must take them into account and provide means to cut all power to the control-
ler’s power stage.
On controllers with STO circuitry an extra test is taken place upon power-up or when-
ever the STT command is executed (see STT - STO Self-Test, p.205). During this test
the FETS are checked whether they are shorted (and so damaged) or not. If either of
them is shorted then the MOSFail bit in the fault flags is set, as long as the EStop bit
and the FETs Off bit in Status flags. This fault is cleared only when the STT runs again
and the MOSFET failure goes away.