US 12,034,395 B2
Apparatus and methods for reduced voltage starting of motors with bumpless force transition
Stan R. Simms, Arden, NC (US); Thomas A. Farr, Arden, NC (US); and Gabriel Teixeira Braga, Belo Horizonte (BR)
Assigned to Eaton Intelligent Power Limited, Dublin (IE)
Filed by Eaton Intelligent Power Limited, Dublin (IE)
Filed on Nov. 4, 2022, as Appl. No. 18/052,879.
Prior Publication US 2024/0154552 A1, May 9, 2024
Int. Cl. H02M 1/34 (2007.01); H02P 6/21 (2016.01)
CPC H02P 6/21 (2016.02) 20 Claims
OG exemplary drawing
 
1. A motor starter comprising:
a plurality of semiconductor switches configured to selectively connect a power source to a motor; and
a controller configured to operate the semiconductor switches to apply a controllable fraction of a full line voltage of the power source to the motor, wherein the controller is further configured to:
apply a first voltage ramp to cause a voltage to be provided from the power source to the motor while maintaining a current flow to the motor to be within a programmable current limit;
determine, based on detecting a speed of the motor, whether the motor has reached a rated motor speed;
determine, in response to determining that the speed of the motor is below the rated motor speed, whether one or more force transition criteria are met, wherein the one or more force transition criteria are correlated with overheating of the semiconductor switches or overheating of a load connected to the motor; and
apply, in response to determining that the one or more force transition criteria are met, a second voltage ramp to increase the voltage provided to the motor to the full line voltage.