Parallel Inverter Synchronization via Average Duty Cycle Control
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Solution Overview
Problem
In aeronautical electrical generation systems with parallel inverters, circulating currents caused by differences in duty cycle and synchronization lead to phase shifts, which are typically mitigated by adding output inductance, increasing system mass, a critical concern in aeronautics.
Innovation Solution
A method involving data processing units to calculate and synchronize an average duty cycle across multiple inverters, ensuring all emit the same output signal, thereby eliminating the need for additional output inductance and reducing mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If output inductance is added to reduce circulating currents, then circulating currents are reduced, but system mass increases
Solution Approach 1:
The invention changes the control parameters of the inverters by implementing an average duty cycle calculation and synchronization method. Each inverter calculates the average of its own duty cycle and received duty cycles, then modulates its output signal accordingly. This parameter adjustment eliminates circulating currents without requiring additional inductance components, thus reducing system mass while maintaining current stability.
Solution Approach 2:
The invention replaces the mechanical/electrical solution of adding physical inductance components with a control-based solution using data processing units and modulation algorithms. Instead of using hardware elements (inductors) to suppress circulating currents, the system uses computational methods to calculate average duty cycles and synchronize output signals, substituting physical components with intelligent control.
2Device complexity
If duty cycle differences exist between parallel inverters, then system complexity is reduced, but phase shifts occur in output currents
Solution Approach 1:
The invention implements a feedback mechanism where each inverter receives duty cycle information from other inverters, calculates the average duty cycle, and adjusts its own output signal accordingly. This feedback loop ensures that all inverters synchronize their output signals to the same duty cycle, eliminating phase shifts while maintaining simple individual inverter designs.
Solution Approach 2:
The invention merges the control strategies of multiple inverters by calculating an average duty cycle from all inverters and applying this common value to all outputs. This merging approach combines the individual duty cycles into a unified control parameter, ensuring synchronized operation and stable output signals without increasing individual inverter complexity.
Data Source
AI summary
The invention concerns a method for controlling an assembly of at least two inverters (1a, 1b) in an electricity generating system with parallel inverters. The method comprises the implementation by at least one data processing unit (2a, 2b) of the steps: (a) for each inverter (1a, 1b) of the assembly, obtaining an input duty factor (PWMi) of an input signal (Si) received by the inverter (1a, 1b), (b) calculating a mean duty factor (PWMm) from the input duty factors (PWMi), (c) modulating and synchronising the input signal (Si) received by each inverter (1a, 1b) into an output signal (So) having an output duty factor (PWMo) corresponding to the mean duty factor (PWMm).