ARCP Converter Leg Timing Control for Parallel Current Balance
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Solution Overview
Problem
Current parallel-connected power converters experience current imbalances due to parameter differences and varying impedances, leading to uneven stress on switch components and premature wear, as well as increased temperature and efficiency losses.
Innovation Solution
The implementation of an auxiliary resonant commutated pole (ARCP) converter system with a resonant swing time controller that adjusts the turn-on instant of auxiliary switching devices to control the resonant swing time duration towards a reference value, ensuring equal current sharing across parallel-connected ARCP converter legs through closed-loop feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple inverter units are connected in parallel to increase output power capability, then the power output is improved, but current imbalance occurs between units due to parameter differences and varying impedances
Solution Approach 1:
The patent implements a feedback mechanism where the actual resonant swing time duration is measured and fed back to the resonant swing time controller. The controller compares the actual value with a reference value and adjusts the turn-on instant of auxiliary switching devices accordingly to maintain equal current sharing among parallel-connected inverter units
Solution Approach 2:
The patent changes the timing parameter (turn-on instant) of auxiliary switching devices dynamically to compensate for parameter differences between parallel-connected inverter units. By adjusting the resonant swing time duration, the system equalizes current distribution without requiring identical component parameters
2Reliability
If switch control pulses are modified to balance currents by delaying turn-on or turn-off instants, then current balance is improved, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The resonant swing time controller autonomously measures the actual resonant swing time duration and automatically adjusts the turn-on instant of auxiliary switching devices without requiring external intervention or complex coordination with other inverter units. Each unit independently equalizes its own current contribution
Solution Approach 2:
The system performs preliminary measurement of the resonant swing time duration and adjusts the switching instants before current imbalance causes excessive stress or temperature rise. The feedback control proactively maintains current balance rather than reacting to overheating or failure conditions
3Power
If higher current flows through switch components to compensate for imbalance, then power output is maintained, but temperature increases and efficiency decreases due to higher dissipated power
Solution Approach 1:
By dynamically adjusting the resonant swing time duration to match the reference value, the system optimizes the current distribution among parallel units. This prevents excessive current through any single unit, reducing I²R losses and improving overall system efficiency while maintaining the required power output
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 solution effectively reduces differential output currents and suppresses circulating currents, leading to more uniform stress distribution and improved efficiency by controlling the resonant swing time to a reference value in each ARCP inverter leg, thereby enhancing the performance and longevity of the power converter system.
Implementation Method 1
an auxiliary resonant commutated pole (ARCP) converter leg, particularly an ARCP half-bridge
Data Source
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AI summary
A power converter system comprises an auxiliary resonant commutated pole (ARCP) converter leg, particularly an ARCP half-bridge, and a resonant swing time controller for the ARCP converter leg. The resonant swing time controller is configured to control a resonant swing time duration of ARCP commutations to a reference value of the resonant swing time by means of a closed loop feedback of an actual resonant swing time duration. In an embodiment, the resonant swing time controller is configured to provide, based on an error (ts_error) between the actual resonant swing time duration (ts_meas) and the reference value (ts_ref ), control values (Aux_delay command) to adjust a turn-on instant of at least one auxiliary switching device of the ARCP converter leg earlier or later in time so that resonant swing time duration of ARCP commutations is controlled towards the reference value.