Two-Phase Rotary Current Controller Phase-Unbalanced Control
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Solution Overview
Problem
Two-phase three-phase controllers face inefficiencies due to unequal root mean square current values in their controlled phases, leading to overdesign of power semiconductors and heat sinks, which increases costs and can result in uneven load distribution and instability, especially with varying rotation directions.
Innovation Solution
Implementing phase-unbalanced control by adjusting the trigger delay for each phase to match root mean square current values, allowing for optimized operation and reduced semiconductor and heat sink requirements, while maintaining functionality in reducing starting currents and torques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three-phase controllers use three sets of thyristors connected back-to-back in parallel, then the reliability and current handling capability are improved, but the cost increases significantly
Solution Approach 1:
The patent extracts one set of thyristors from the traditional three-phase controller configuration, reducing from three sets to two sets. This is achieved by utilizing the neutral point and implementing a control method that allows one phase to be controlled through the existing two thyristor sets, thereby reducing component count and cost while maintaining functional capability
Solution Approach 2:
The two thyristor sets are designed to perform multiple functions: they control two phases directly and, through the control method described in the patent, can also control the third phase by utilizing the neutral point. This multi-functionality allows the reduced component configuration to achieve three-phase control capability
2Ease of manufacture
If two-phase three-phase controllers are used with only two sets of thyristors, then the cost is reduced, but the root mean square current values in the two controlled outer conductors become unequal
Solution Approach 1:
The patent intentionally introduces asymmetry in the control parameters of the two thyristor sets. By applying different trigger delay angles (α1 and α2) to the two phases, the control method compensates for the unequal current distribution caused by the two-phase configuration, thereby achieving balanced current values in both outer conductors
Solution Approach 2:
The patent changes the control parameters (trigger delay angles) of the two thyristor sets to different values. This parameter adjustment allows the system to compensate for the inherent current imbalance in two-phase controllers and achieve equal root mean square current values in both controlled conductors
3Reliability
If power semiconductors are designed for higher current values to handle maximum current, then the current handling capability is improved, but the cost and device size increase
Solution Approach 1:
The patent implements a control method that monitors and balances the current values in the two controlled outer conductors. By using feedback control with different trigger delay angles, the system ensures that neither phase exceeds the designed current capacity, allowing power semiconductors to be sized for the actual operating conditions rather than worst-case scenarios
Data Source
AI summary
A method is disclosed for operating a two-phase rotary current controller. In order to optimize the operation of a two-phase rotary current controller, magnitudes of a parameter that can be varied in both controllable phases of a two-phase rotary current controller is matched in these phases. In particular, the existing principle of phase-symmetric control with a uniform ignition delay in both controlled outer conductors is abandoned, and a separate ignition delay is stipulated for each of the two controlled outer conductors.