Electric motor

1. A system comprising an electric motor and an external receiving unit, the electric motor comprising a housing, a stator, a rotor with a rotor winding or permanent magnets, a thermal protection device to protect the electric motor from overheating, the thermal protection device comprising a sensor unit housed on the rotor, the sensor unit having a temperature sensor for detecting temperature-based measured values, a radio module with antenna for transmitting sensor signals of temperature-based measured values, and a microcontroller, and the sensor unit receiving operating power by induction from the coil and stator,

wherein the sensor unit comprises a memory, and data derived from the temperature-based measured values are transmitted to the external receiving unit via radio, the sensor unit being configured to transmit data packets at spaced apart time intervals to transmit the sensor signals of temperature-based measured values or data or information derived therefrom, and the sensor unit being configured to transmit a data packet repeatedly in successions;

wherein the sensor unit transmits a same data packet at least twice over a specified rotor offset.

2. The system according to claim 1 , wherein the electrical power for operating the sensor unit is induced from alternating fields or is drawn off via a tap of a collector.

3. The system according to claim 1 , wherein the antenna comprises a loop antenna or a ceramic antenna.

4. The system according to claim 1 , wherein an SRD (short range) ISM band is provided as the working frequency.

5. The system according to claim 1 , wherein the radio power of the radio transmission is set at least essentially to a radius of up to 30 m.

6. The system according to claim 1 , wherein the sensor unit carries out a tuning routine of the antenna for transmitting the sensor signals or the data or information derived therefrom via radio to the external receiving unit.

7. He system according to claim 6 , wherein the tuning routine of the antenna is performed during initial start-up and/or during operation before a data packet is sent.

8. The system according to claim 6 , wherein the adjustment parameters determined from the tuning routine of the antenna are stored in the memory of the sensor unit.

9. The system according to claim 1 , wherein a maximum transmission power of 30 mW, and/or a data rate of 50 kbit/s is provided for the transmission.

10. The system according to claim 1 , wherein for the transmission, a duration of the data packet is less than or equal to 0.1% of a holding time of the channel.

11. The system according claim 1 , wherein the sensor unit is configured to transmit measured values or data or information derived therefrom which contain the following:

an individual address of the sensor unit and/or test data for parity measurement and/or rotational speed of the rotor and/or vibration data of the rotor axis or of the rotor and/or positive and/or negative acceleration and/or a blockage of the rotor and/or data on operating states above a limit temperature, as a time measurement and/or sensor unit data relating to self-supply and energy management.

12. The system according to claim 1 , wherein power and/or operation of the electric motor is controlled based on temperature-based measured values and further additional measured values or data or information derived therefrom.