| CPC H02P 25/04 (2013.01) [H02P 21/18 (2016.02); H02P 27/045 (2013.01)] | 27 Claims | 

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               20. A system for controlling inducer motor speed, the system comprising: 
            a switching device configured to be operable for changing stator voltage of an inducer motor; 
                a speed sensor configured to be operable for determining actual inducer motor speed; and 
                a control configured to be operable for changing the stator voltage of the inducer motor to a value at which the actual inducer motor speed is controllably regulated and/or maintained substantially at a set speed without significant speed oscillations; 
                wherein: 
                the control is operable for determining whether the actual inducer motor speed is greater than a sum of the set speed plus a first delta speed; and 
                  upon the control determines that the actual inducer motor speed is greater than the sum of the set speed plus the first delta speed, then the control is operable for reducing the actual inducer motor speed by using the switching device with a higher firing angle to thereby obtain a lower stator voltage for the inducer motor; 
                wherein if the control determines that the actual inducer motor speed is not greater than the sum of the set speed plus the first delta speed, then the control is operable for determining whether the actual inducer motor speed is less than a difference of the set speed minus a third delta speed. 
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