Synchronous Motor Field Discharge Resistor Thermal Management
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Solution Overview
Problem
Existing field discharge resistor units in synchronous motors are vulnerable to thermal damage and difficult to adjust resistance values and heat capacity, leading to reduced operational reliability.
Innovation Solution
A field discharge resistor unit with a hub coupled to a rotary shaft, featuring conductor disks that function as resistors, allowing for adjustable resistance and heat capacity through varying the number and shape of disks, and enhanced cooling via air flow channels and fan blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a wound coil type field discharge resistor is used, then the resistor can be integrated into the motor structure, but thermal damage occurs in insulation and operational reliability degrades
Solution Approach 1:
The field discharge resistor is segmented into multiple conductor bars arranged in series, with each bar isolated from others by insulating material. This segmentation prevents thermal damage from propagating through the entire structure and eliminates the need for complex wound coils, thereby improving reliability while maintaining integration.
2Device complexity
If a wound coil type field discharge resistor is used, then the resistor structure is compact, but resistance value and heat capacity cannot be easily adjusted
Solution Approach 1:
The resistor structure uses individual conductor bars that can be independently selected, added, or removed from the series configuration. This dynamic arrangement allows the resistance value and heat capacity to be easily adjusted by changing the number or configuration of active conductor bars, while the overall compact structure is maintained through the modular bar design.
3Ease of operation
If direct-on-line starting is used, then the motor can be started simply, but high voltage is induced into the rotor coil causing thermal damage
Solution Approach 1:
The field discharge resistor acts as an intermediary component connected to the rotor coil. During direct-on-line starting, it provides a controlled discharge path for induced high voltage, limiting the current magnitude and preventing thermal damage to the rotor coil insulation, thereby enabling simple starting operation without compromising safety.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides improved thermal stability and reliability by reducing thermal damage during motor startup and allowing for easy adjustment of resistance and heat capacity, enhancing the motor's operational performance.
Implementation Method 1
the field discharge resistor unit includes a hub which has a receiving space therein and is coupled to the rotary shaft of the synchronous motor so that a rotary movement of the hub matches that of the shaft; and at least one conductor disk received in the receiving space of the hub and may function as a resistor when an electric current flows therethrough
Data Source
AI summary
A field discharge resistor unit according to an embodiment of the present invention is a device coupled to a rotary shaft of a synchronous motor and connected to a coil wound on a rotor of the synchronous motor, to reduce a magnitude of an electric current flowing through the coil wound on the rotor, and comprises: a hub which has a receiving space therein and is coupled to the rotary shaft of the synchronous motor so that a rotary movement of the hub matches that of the shaft; and at least one conductor disk received in the receiving space of the hub and may function as a resistor when an electric current flows therethrough.