4.642.536 2/1987 Boyd, Jr. et al 318/254 X
4.642.537 2/1987 Young 318/254 X
4,654,566 3/1987 Erdman 318/254 X
4,857,814 8/1989 Duncan 318/138 X
Primary Examiner—William M. Shoop, Jr.
Assistant Examiner—David Martin
Attorney, Agent, or Firm—Trexler, Bushnell, Giangiorgi
& Blackstone, Ltd.
A method of cyclically accelerating an electric motor for example for use during an agitation cycle in a laundry machine. A desired speed, direction of rotation and acceleration time is set and power is applied to the motor in a series of incremental steps, each successive step corresponding to an increase in the level of power applied during the previous step. The steps are initially estimated to be sufficient to enable sufficient energy to be supplied to the motor for it to reach the desired speed in the acceleration time. The speed of the motor is monitored and the steps of accelerating the motor are repeated with the series of incremental steps adjusted to adjust the supply of energy to the motor dependant on the speed reached in the acceleration time of the previous cycle.
13 Claims, 3 Drawing Sheets