Parallel Converter Leg Gate Voltage Adjustment for Current Sharing
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Solution Overview
Problem
Current imbalance in parallel-connected power converters leads to uneven stress and premature wear of switch components due to differing impedances and switch component parameters, resulting in higher dissipated power and temperature.
Innovation Solution
Implement an autonomous leg-specific gate voltage adjustment for each parallel-connected converter leg based on leg-current-related information to balance current sharing without requiring information exchange between legs, using controllable semiconductor power switching devices and a control arrangement to adjust gate voltages inversely proportional to leg current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If parallel-connected converter legs use identical control signals, then system simplicity is maintained, but current imbalance occurs due to parameter differences and differing impedances
Solution Approach 1:
The patent applies local quality by providing each converter leg with an individual gate voltage adjustment mechanism that operates autonomously based on its own current measurements. Each leg has its own control arrangement that modifies gate voltages locally according to its specific current conditions, allowing each component to be optimized for its local operating conditions rather than forcing uniform control across all legs.
Solution Approach 2:
The control arrangement enables self-service by allowing each converter leg to autonomously adjust its own gate voltages based on its own current measurements without requiring communication or coordination with other legs. The leg with higher current automatically reduces its gate voltage, while the leg with lower current maintains or increases its gate voltage, creating a self-regulating current balancing mechanism.
2Productivity
If gate voltage is increased to boost current in a converter leg, then current capability is improved, but power dissipation and temperature increase
Solution Approach 1:
The patent implements feedback by continuously measuring the current in each converter leg and using this measurement to dynamically adjust the gate voltages. The control arrangement monitors the actual current output and modifies the gate voltage accordingly, creating a closed-loop control system that automatically responds to changes in operating conditions and maintains optimal current distribution.
Solution Approach 2:
The patent applies parameter changes by dynamically varying the gate voltage parameter based on measured current conditions. When a converter leg draws excessive current, the system changes the gate voltage parameter to reduce it, thereby controlling power dissipation and temperature without requiring manual intervention or system shutdown.
3Manufacturing precision
If switch component parameters are standardized across all converter legs, then manufacturing consistency is improved, but current imbalance persists due to impedance differences in parallel branches
Solution Approach 1:
The patent applies dynamics by transitioning from static, identical control signals to dynamic, adaptive gate voltage adjustments. The gate voltages are no longer fixed or identical but continuously vary based on real-time current measurements, allowing the system to adapt to parameter variations and impedance differences that exist despite manufacturing precision.
Data Source
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AI summary
In a power converter system, converter legs (INV1, INV2) are connected in parallel between a common dc system (4) and a common ac system (6) or between two common dc systems to provide respective leg currents (Iο1, Io2). A gate driver circuitry is coupled to provide dedicated gate voltages to gates of controllable semiconductor switching devices (S11, S21, S12, S22) of parallel-connected converter legs. A control arrangement is configured to balance a current sharing between the parallel-connected converter legs (INV1, INV2) by means of having an individual autonomous leg-specific gate voltage adjustment for the semiconductor power switching devices of each of parallel connected converter legs in function of the leg current (Io1, I02) or leg-current-related information of the respective converter leg.