Armature Winding Five Parallel Circuits Voltage Balance
Solution Overview
Problem
In large-capacity rotating electrical machines with indirect cooling, armature windings with multiple parallel circuits face issues of voltage imbalance and circulating currents due to increased thermal resistance and current density, necessitating a balanced configuration to minimize losses.
Innovation Solution
A three-phase even-numbered-pole armature winding with five parallel circuits is housed in 45 slots per pole, divided into phase belts with specific coil piece arrangements to achieve balanced voltage and phase angle deviations, using jumper wires to connect coil pieces in series and reduce interference between connection and lead-out conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the voltage of armature winding is increased, then the machine capacity is improved, but the thickness of main insulation is increased causing current density to increase and loss to increase
Solution Approach 1:
The armature winding is divided into five parallel circuits instead of using a single series circuit. This segmentation allows the voltage across each circuit to be reduced while maintaining the total machine capacity, thereby reducing the required insulation thickness and current density in each circuit, which ultimately reduces energy loss.
2Reliability
If the thickness of main insulation is increased, then the voltage withstand capability is improved, but the cross-sectional area of conducting portion is reduced causing current density to increase
Solution Approach 1:
By dividing the armature winding into five parallel circuits, the voltage across each circuit is reduced to one-fifth of the total voltage. This reduction allows the use of thinner main insulation while maintaining adequate voltage withstand capability, thereby preserving the cross-sectional area of the conducting portion and reducing current density and energy loss.
3Temperature
If the number of parallel circuits is increased, then the cooling capacity is improved, but the voltage imbalance between circuits increases causing circulating current to increase
Solution Approach 1:
The patent applies local quality by strategically placing coil pieces of different parallel circuits in specific slots within phase belts. This non-uniform distribution pattern ensures that each parallel circuit generates equal voltage despite the increased number of circuits, thereby eliminating circulating currents while maintaining improved cooling capacity through the five-parallel-circuit configuration.
4Reliability
If coils of each parallel circuit are placed in phase belts, then the voltage balance is improved, but the complexity of coil placement increases
Solution Approach 1:
The patent employs preliminary action by pre-planning and specifying the exact slot positions for coil pieces of each parallel circuit within the phase belts. This predetermined arrangement pattern simplifies the manufacturing process by providing clear placement guidelines, reducing the actual complexity during assembly while achieving balanced voltage generation across all five parallel circuits.
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
This configuration effectively balances voltage and phase angle deviations, reducing circulating currents and enhancing the reliability and efficiency of the armature winding, suitable for indirect cooling type large-capacity rotating electrical machines.
Implementation Method 1
an armature winding is provided with upper and lower coil pieces arranged in slots of a laminated iron core
Implementation Method 2
in an indirect cooling type machine in which the armature winding is cooled from an outer side of the main insulation
Data Source
AI summary
According to one embodiment, there is provided a three-phase even-numbered-pole two-layered armature winding housed in forty five slots per pole provided in a laminated iron core. Coil pieces corresponding to first and second parallel circuits are arranged in the first phase belt, coil pieces corresponding to fourth and fifth parallel circuits are arranged in the second phase belt, coil pieces corresponding to the third parallel circuit are arranged in the first and second phase belts, and the upper coil pieces and the lower coil pieces of each parallel circuit are placed in same-numbered positions from a pole center.