Electric motor and method for controlling the same
First Claim
1. A single phase universal electric motor of a portable electric tool, the motor including a stator, a rotor assembly with a central rotor shaft and rotor windings, and a motor control system, the motor control system including:
- a current measuring device for directly or indirectly measuring the electric current in the rotor windings providing a rotor current value,an ambient temperature measuring device for measuring or estimating the ambient air temperature providing an air temperature value, and,a rotor temperature estimation device for determining a new rotor temperature estimate utilizing the rotor current value and the air temperature value.
1 Assignment
0 Petitions
Accused Products
Abstract
An electric motor (100) having a motor control system (400) including: —a current measuring means (402) for directly or indirectly measuring the electric current in the rotor windings (7) providing a rotor current value/s, —an ambient temperature measuring/estimation means (404) for measuring or estimating the ambient air temperature providing an air temperature value/s, —a rotor temperature estimation means (406, 407, 408, 409, 410, 411) for estimating a rotor temperature at least based on the rotor current value/s and the air temperature value/s, and—a current limiting means (405) for preventing overheating/burning of the rotor assembly (3) by limiting the electric current to the rotor windings (7) when the estimated rotor temperature exceeds a predetermined overheating threshold (412).
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Citations
17 Claims
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1. A single phase universal electric motor of a portable electric tool, the motor including a stator, a rotor assembly with a central rotor shaft and rotor windings, and a motor control system, the motor control system including:
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a current measuring device for directly or indirectly measuring the electric current in the rotor windings providing a rotor current value, an ambient temperature measuring device for measuring or estimating the ambient air temperature providing an air temperature value, and, a rotor temperature estimation device for determining a new rotor temperature estimate utilizing the rotor current value and the air temperature value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for controlling a single phase universal electric motor of a portable electric tool, the motor comprising a stator and a rotor assembly with a rotor shaft and rotor windings, the method comprising:
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a) determining a rotor current value by measuring the electric current in the rotor winding, b) determining an air temperature value by measuring the ambient air temperature, c) determining a rotor speed value by measuring the rotational speed of the rotor, d) determining a rotor temperature based on said rotor current value of step a), said air temperature value of step b), and on said rotor speed value of step c). - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification