Method for operating a universal motor

• US 10,461,680 B2
• Filed: 10/07/2014
• Issued: 10/29/2019
• Est. Priority Date: 10/17/2013
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Wiszniewski, Jacek, Dengler, Klaus
• Primary Examiner(s): Islam, Muhammad S
• Application Number:
  US15/029,438
• Publication Number:
  US 20160254773A1
• Time in Patent Office: 1,848 Days
• Field of Search: 318375, 318 11, 318 55, 318635, 318 88, 318104
• CPC Class Codes: H02P 1/16 for starting dynamo-electric motors or dynamo-electric converters
• CPC Class Codes: H02P 1/18 for starting an individual dc motor
• CPC Class Codes: H02P 25/14 Universal motors H02P25/12 takes precedence
• CPC Class Codes: H02P 3/06 for stopping or slowing an individual dynamo-electric motor or dynamo-electric converter

Abstract

A method for operating a universal motor, comprising the following steps: —establishing a synthetic variable from at least two physical operating parameters of the universal motor; and —operating the universal motor using operating parameters of this type so that the synthetic variable remains at a substantially constant level or at least does not exceed a defined permissible upper limit.

Claims

1. A method for operating a universal motor, the method comprising:

measuring a first physical operating variable corresponding to a rotational speed of an armature in the universal motor;

measuring a second physical operating variable corresponding to one of an amperage, armature voltage, and armature field voltage, in the universal motor;

ascertaining with a control device a synthetic variable corresponding to a mathematical combination of the first physical operating variable and the second physical operating variable; and

operating the universal motor with the control device to influence a firing angle to adjust the second physical operating variable to maintain the synthetic variable at or below a predetermined level while the rotational speed of the armature in the universal motor changes during at least one of a braking and a start-up operation to reduce or eliminate sparking from a plurality of brushes in the universal motor.

2. The method as claimed in claim 1, the operating the universal motor further comprising:

operating the universal motor with the control device to influence the firing angle of the motor to adjust the second physical operating variable to maintain the synthetic variable at a substantially constant level while the rotational speed of the universal motor changes.

3. The method as claimed in claim 1, the operating the universal motor further comprising:

ascertaining with the control device the synthetic variable as a product of (i) the rotational speed of the armature, and (ii) an amperage in the universal motor.

4. A universal motor comprising:

a commutator;

a plurality of brushes;

an armature; and

a control device configured to control a firing angle of an electrical signal supplied to the plurality of brushes and the commutator to turn the armature, the control device being configured to;

measure a first physical operating variable corresponding to a rotational speed of an armature in the universal motor;

measure a second physical operating variable corresponding to one of an amperage, armature voltage, and armature field voltage, in the universal motor;

ascertain a synthetic variable corresponding to a mathematical combination of the first physical operating variable and the second physical operating variable; and

operate the universal motor to influence a firing angle to adjust the second physical operating variable to maintain the synthetic variable at or below a predetermined level while the rotational speed of the armature in the universal motor changes during at least one of a braking and a start-up operation to reduce or eliminate brush sparking in the universal motor.

5. The universal motor as claimed in claim 4, the control device being further configured to:

operate the universal motor to influence the firing angle of the motor to adjust the second physical operating variable to maintain the synthetic variable at a substantially constant level while the rotational speed of the universal motor changes.

6. The universal motor as claimed in claim 4, the control device being further configured to:

ascertain the synthetic variable as a product of (i) the rotational speed of the armature, and (ii) an amperage in the universal motor.