Rotor Temperature Estimation Using Node-Based Thermal Loss Balance

The patent uses an intermediary thermal model that mediates between difficult-to-measure rotor temperatures and easily measurable stator temperatures. The model acts as a virtual sensor, translating accessible electrical measurements into rotor temperature estimates without physical contact, thereby avoiding the complexity of direct thermocouple installation while maintaining measurement accuracy.

The patent replaces the mechanical thermocouple measurement system with an electrical-field-based thermal model. Instead of physically inserting sensors into the rotor, the system uses electrical measurements from the stator and a computational thermal model to estimate rotor temperatures, substituting a complex mechanical sensing system with a simpler electrical measurement and calculation approach.

The patent adapts the thermal model by changing key parameters specific to DFIM rotors, including copper losses, iron losses, and ventilation losses. By modifying the loss calculation parameters and thermal resistance values to reflect rotor-specific conditions rather than transformer conditions, the model maintains structural simplicity while achieving accurate temperature predictions for the rotating machine.

The patent introduces dynamic elements to account for the rotating operation of the DFIM rotor. The thermal model incorporates rotational speed variations and their effect on ventilation losses and heat dissipation, transforming a static transformer model into a dynamic rotor model that adapts to changing operating conditions while maintaining computational efficiency.

The patent employs the stator as an intermediary measurement point to indirectly infer rotor temperatures. Rather than placing sensors directly on the rotating rotor where reliability is compromised, the system measures temperatures and electrical parameters on the stationary stator and uses a thermal model to calculate rotor temperatures, thereby obtaining the needed data without exposing sensors to the harsh rotating environment.

The patent creates a virtual copy of the rotor thermal state through computational modeling. Instead of physically measuring rotor temperatures with sensors, the system generates a digital replica of the rotor's thermal conditions by solving the thermal differential equations based on stator measurements, providing accurate temperature information without physical intrusion into the rotor.

The patent performs preliminary setup by defining the thermal model parameters, thermal resistances, and loss coefficients before operation. Once configured, the real-time monitoring requires only substitution of measured electrical values into pre-established equations, significantly reducing the computational complexity during actual operation while maintaining continuous safety monitoring capability.

The patent implements a balanced level of real-time calculation by focusing on critical temperature points in the rotor rather than computing the entire thermal field. By calculating only the most relevant temperatures needed for safety monitoring, the system achieves adequate operational safety without the excessive computational burden of a complete thermal analysis.