Safe torque off using digital isolator

A control system for safe torque off (STO) operation, comprising:

• a motor;
• a digital signal processor (DSP) which outputs a multi-phase low side pulse width modulation (PWM) signal and a multi-phase high side PWM signal;
• an inverter receptive of the multi-phase low side PWM signal and the multi-phase high side PWM signal, the inverter being configured to combine the multi-phase low side PWM signal and the multi-phase high side PWM signal into a multi-phase high-voltage output to control the motor;
• and
• a digital isolator electrically interposed between the DSP and the inverter and configured to selectively block at least a portion of the multi-phase high side PWM signal from being received by the inverter.

A method of controlling safe torque off (STO) operation of an elevator system, the method comprising:

• outputting, from a digital signal processor (DSP), a multi-phase low side pulse width modulation (PWM) signal and a multi-phase high side PWM signal;
• combining, in an inverter, the multi-phase low side PWM signal and the multi-phase high side PWM signal into a multi-phase high-voltage output to control a motor;
• determining that the STO operation is in effect;
• and
• blocking, at a digital isolator electrically interposed between the DSP and the inverter, at least a portion of the multi-phase high side PWM signal from being received by the inverter.