Why is the Slip Ring Ventilation and Cooling Structure Used in Wound Rotor Motors?

 Introduction

Wound - rotor asynchronous motors are widely used in heavy - duty equipment such as mining machinery, port cranes, and metallurgical rolling mills due to their wide speed - regulation range and high torque output. During long - term operation, the slip ring, which is a component for current transmission and signal control in winding motors, often suffers from overheating problems. This, in turn, leads to a decline in the overall lifespan and efficiency of the motor.

To address this issue, the ventilation and cooling structure of the slip ring has been designed. But do you know why the slip ring heats up and how this structure dissipates heat? Today, we will discuss this issue in this article.

 

Heat Source Analysis of the Slip Ring in Wound Rotor Motors

The slip ring connector transfers power, data, and signals between the rotor circuit of the wound rotor motor and the external stationary circuit. This is achieved through the sliding contact between the rotating conductive ring and the fixed brush. During operation, the causes of its heat generation generally include:

(1) Joule Heat from Contact Resistance: The microscopic unevenness of the contact surface between the brush and the conductive ring can lead to an increase in local resistance, generating heat (Q = I²R).

(2) Heat Generated by Friction: During high - speed rotation, the mechanical friction between the brush and the ring further intensifies the temperature rise.

(3) Environmental Heat Conduction: The heat loss from the internal windings and core of the motor is transferred to the slip ring area through air convection.



Definition and Design of the Slip Ring Ventilation and Cooling Structure

The slip ring ventilation and cooling structure is an active heat - dissipation solution that reduces the temperature rise of the slip ring by forced air - flow circulation. It integrates the principles of fluid mechanics and thermodynamics.

(1) Core Components

 Air Duct System: Directional guide plates are designed inside the slip ring cavity to guide the cooling air flow to flow along the surface of the slip ring.

 Centrifugal Fan: Integrated at the end of the motor shaft, it uses the rotational power of the rotor to drive air circulation.

 Enhanced Heat Sink: This is a fin - like structure added to the outer surface of the slip ring to increase the heat - dissipation area.

 Filter Module: Generally, a metal wire mesh and non - woven fabric are installed at the inlet for filtering to prevent dust from invading.


(2) Common Cooling Modes

Type

Air - flow Path

Applicable Scenarios

Axial Ventilation

Flows parallel to the motor axis

Medium - and low - speed motors (< 1500 rpm)

Radial Ventilation

Spreads spirally perpendicular to the axis

High - speed motors (> 1500 rpm)


Why Use This Structure in Wound Rotor Motors?

(1) Improve Heat - dissipation Efficiency: Experimental data from IEEE Xplore shows that under the same load, the surface temperature of the slip ring with an axial ventilation structure can be reduced by 25 - 35°C (compared to natural cooling), and the temperature - rise curve becomes gentler.

(2) Prolong Component Lifespan: When the brush wear rate of the slip ring is reduced by more than 50%, the replacement cycle can be extended from 3 months to 6 - 8 months. This also makes the stability of the surface oxide film higher.

(3) Enhance System Operating Stability: A stable operating temperature enables the slip ring to maintain a contact resistance fluctuation range of ±5% (±15% for the traditional structure), reducing the interference of current harmonics on the control system.

(4) Optimize Environmental Adaptability: By adjusting the cross - sectional area of the air duct and the fan inclination angle, the slip ring can adapt to a wider temperature range of operating conditions, such as from - 40°C to +60°C.


BYTune: Custom - made Slip Ring Solutions for Your Motors

As a slip ring provider with over 26 years of focus on industrial transmission systems, BYTune offers full - life - cycle slip ring custom olutions, including:

 Precise Air Duct Design: Based on ANSYS Fluent's fluid - thermal coupling analysis, we will optimize the air - duct structure and material selection.

 Modular Component Library: This covers slip rings with diameters ranging from 3 - 500 mm, supporting the rapid configuration of axial/radial/mixed ventilation solutions.

Contact BYTune engineers now to get your exclusive heat - dissipation optimization solution!

 

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