Parallel Modular Converter Load Balancing for Circulating Current Reduction

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Solution Overview

Problem

Conventional power distribution systems in vehicles require multiple oversized motor controllers, leading to excessive capacity, underutilization, and inefficiency, as each controller is sized for maximum load with safety margins, despite most motors operating at lower capacities and intermittently.

Innovation Solution

A modular power distribution system with parallel modular converter modules that can operate individually or in parallel, using a load balancer to monitor and equalize output currents, reducing circulating current and phase-to-phase imbalances, and dynamically reconfiguring to meet power demands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple oversized motor controllers are used to meet maximum power demands, then system reliability and power capacity are improved, but device complexity and underutilization increase

Engineering Contradiction:

Improvesystem reliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system divides the power control function into multiple modular converter modules, each capable of operating independently or in parallel. This segmentation allows the system to scale capacity by adding modules rather than using fewer oversized controllers, reducing complexity while maintaining reliability through modular redundancy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically reconfigures the parallel modular converters based on real-time power demands and module performance. Controllers can be dynamically assigned to different loads, and modules can be taken offline for maintenance or replaced without shutting down the entire system, enhancing reliability while optimizing resource utilization.

Inventive Principle:

Principle #15Dynamics

2Reliability

If each motor controller is sized for maximum load with safety margins, then system reliability is improved, but efficiency deteriorates due to underutilization

Engineering Contradiction:

Improvesystem reliabilityVSAvoidefficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Each modular converter module is designed with universal functionality to handle various power levels and be assigned to different loads. The modules can operate individually or in parallel combinations, allowing the system to efficiently match controller capacity to actual load requirements rather than always using oversized controllers at partial capacity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system changes operational parameters by dynamically adjusting which modules are active and how they are configured in parallel based on real-time power demands. This allows the system to optimize efficiency by using only the necessary capacity while maintaining reliability through the ability to scale up by activating additional modules when needed.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If parallel modular converters are used to reduce underutilization, then efficiency is improved, but circulating current and phase-to-phase imbalances increase

Engineering Contradiction:

ImproveefficiencyVSAvoidcirculating current

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The system incorporates feedback mechanisms that continuously monitor the output of each modular converter module and adjust control parameters to balance load distribution. This feedback control eliminates circulating currents by ensuring that parallel modules share loads equally and corrects phase-to-phase imbalances by adjusting module output based on real-time measurements.

Inventive Principle:

Principle #23Feedback

4Device complexity

If fixed motor controller assignments are used, then system simplicity is maintained, but adaptability deteriorates when failures or changing demands occur

Engineering Contradiction:

Improvesystem simplicityVSAvoidadaptability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The system transitions from fixed controller assignments to dynamic, reconfigurable assignments where controllers can be automatically reassigned based on module status and power demands. This dynamic capability allows the system to adapt to failures by redistributing loads to healthy modules and to changing demands by optimizing the configuration of parallel modules, all while maintaining relatively simple operation through automated control.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9991719B2Systems and methods for reducing circulating current and phase to phase imbalance in a parallel modular converter system

Publication Date: 2018.06.05 THE BOEING CO

AI summary

A system and method for providing power to a vehicle with reduced circulating current and phase-top-phase imbalance is disclosed. The system can include a plurality of parallel module converter for prioritizing and allocating each electrical load to one or more parallel modular converter modules. The system can also comprise a load balancer to ensure that differences in the properties (e.g., impedance) of the parallel modular converter modules do not create circulating currents or phase-to-phase imbalances. The load balancer can monitor the outputs to the plurality of parallel modular converter modules and modify the inputs to equalize, synchronize, or both the outputs.