Rotary speed control for a universal motor, in particular for a washing machine drive

US6854299B2 · kind B2 · utility

Assignee

• Diehl AKO Stiftung & Co. KG · DE

Inventors

• Martin Weinmann · Bad Waldsee, DE
• Roland Morent · Schallstadt, DE

Key dates

• Filing date: Jan 5, 2004
• Grant date: Feb 15, 2005
• Expiry date: Jan 5, 2024

Classification

• Technology area (CPC H): Electricity
• CPC primary: H02P25/14
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

In the context of a single-phase universal motor, which has proven its worth in particular as an agile washing machine drive, the novel control provides for a substantial reduction in the remagnetization losses, rotary speed dependency, level of efficiency, and the fluctuations in the motor current pulsating at double the mains frequency, together with the resulting losses and production of noise in particular because of torque fluctuations and electromagnetically excited oscillations of the stator iron core. The motor is no longer operated by way of the phase-angle control, which is synchronized with the mains frequency, of a pulse-fired triac which is self-turning off with the current zero crossing and also no longer operated by way of the pulse duty factor of a chopper oscillating freely at high frequency. Instead, a power switch is switched on and off electronically to conduct in mains relationship over variable periods of time from before the end of a mains half-period to after the beginning of the following mains half-period. The motor current remains virtually unchanged during the switching gaps by way of a free-wheeling diode.