Claims
- 1. A method for detecting a temperature of a starting motor with a still stationary rotor having a complex impedance with a real and an imaginary element, the method which comprises:determining values of a current and a voltage of the starting motor with the still stationary rotor; and determining a motor temperature of the starting motor with the still stationary rotor by determining a value of a real element R of a motor impedance of the starting motor with the still stationary rotor and comparing with a value of a real element R of a motor impedance which have been obtained at a known temperature, in which the real element R of the motor impedance is determined by the relationships R=U^22P(1+1-4ω2L2P2U^4)andL=L1σ+L′2σfrom the measured values and known characteristic variables for the motor, whereÛ=peak value of the voltage P=DC component of power L=inductance in a motor equivalent circuit L1σ=inductance of a stator L′2σ=inductance of a rotor, transposed to the stator ω=2πf.
- 2. The method according to claim 1, which comprises determining the real element R of the motor impedance by digital calculation.
- 3. The method according to claim 1, which further comprises:determining a power signal having a DC element and an AC element by analog multiplication of the current and the voltage; and extracting the DC element from the power signal.
- 4. The method according to claim 3, wherein the power signal AC element has a frequency of twice a mains frequency; and further comprising eliminating the AC element from the power signal.
- 5. The method according to claim 4, which comprises obtaining the DC element from the power signal by low-pass filtering.
- 6. A method for detecting a temperature of a starting motor with a still stationary rotor having a complex impedance with a real and an imaginary element, the method which comprises:determining values of a current and a voltage of the starting motor with the still stationary rotor; and determining a motor temperature of the starting motor with the still stationary rotor by determining a value of a real element R of a motor impedance of the starting motor with the still stationary rotor and comparing with a value of a real element R of a motor impedance which have been obtained at a known temperature, where the real element R of the motor impedance is determined from the relationship R=U^I^cos φfrom electrical variables, whereÛ=peak values of the voltage: Î=peak value of the current, and ψ=phase shift between the voltage and the current.
- 7. The method according to claim 6, wherein the voltage has a constant amplitude.
- 8. The method according to claim 6, which comprises determining the real element R of the motor impedance by digital calculation.
Priority Claims (1)
Number |
Date |
Country |
Kind |
197 43 046 |
Sep 1997 |
DE |
|
CROSS-REFERENCE TO RELATED APPLICATION
This is a continuation of copending International Application PCT/DE98/02800, filed Sep. 21, 1998, which designated the United States.
US Referenced Citations (5)
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DE |
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Non-Patent Literature Citations (1)
Entry |
Japanese Patent Abstract No. 08159890 (Atsushi), dated Jun. 21, 1996. |
Continuations (1)
|
Number |
Date |
Country |
Parent |
PCT/DE98/02800 |
Sep 1998 |
US |
Child |
09/537884 |
|
US |