Multi Output Inverter Ripple Current Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Large DC to AC inverters face challenges with high ripple current, which leads to increased heat production, reduced battery life, and potential for audible interference and equipment reset due to insufficient reservoir capacitors, as well as issues with load dump transients and the need for frequent maintenance of brushed DC motors.
Innovation Solution
A multi-output DC to AC inverter with phase controllers that dynamically adjust the phase, frequency, and waveform of output channels to minimize ripple current and manage load distribution, incorporating a switching network to consolidate or split output channels and connect loads efficiently, while also measuring equivalent series resistance for energy store degradation monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the inverter uses a standard reservoir capacitor, then the circuit is simple and cost-effective, but the ripple current causes increased heat production and reduced battery life
Solution Approach 1:
The invention segments the capacitor bank into multiple individual capacitors (typically three) connected in parallel, each with its own ESR. This segmentation allows the ripple current to be distributed across multiple components, reducing the thermal stress and wear on each individual capacitor and the battery, thereby extending system life while maintaining circuit simplicity
Solution Approach 2:
The invention combines multiple capacitors in parallel to create an equivalent capacitance that behaves like a single larger capacitor with lower effective ESR. This merging approach reduces the overall ripple voltage and heat generation while keeping the circuit design simple and cost-effective
2Power
If the inverter draws high ripple current from the DC supply, then the power delivery is sufficient, but the ripple voltage causes audible interference and equipment reset
Solution Approach 1:
Multiple capacitors are combined in parallel to create a larger equivalent capacitance that can absorb more ripple current. This reduces the ripple voltage amplitude, preventing it from reaching levels that would cause audible interference in audio equipment or trigger under-voltage protection circuits
Solution Approach 2:
The invention converts the harmful ripple current into a beneficial effect by using it to charge multiple capacitors in parallel. The distributed charging action across multiple capacitors with combined capacitance smooths out the voltage ripple, transforming the problematic high-current draw into a controlled charging process that benefits the entire system
3Reliability
If the inverter uses a larger reservoir capacitor to reduce ripple current, then the ripple voltage is reduced, but the cost and size of the capacitor bank increases
Solution Approach 1:
Instead of using one large expensive capacitor, the invention segments the required capacitance into multiple smaller, more economical capacitors connected in parallel. This segmentation achieves the same or better ripple reduction performance while using readily available, cost-effective standard capacitor values
Solution Approach 2:
The invention uses multiple smaller, cheaper capacitors that can be individually replaced if needed, rather than one large expensive capacitor. This approach reduces the overall cost of the capacitor bank while achieving the desired ripple current management performance
4Device complexity
If the inverter consolidates output channels to reduce complexity, then the control system is simpler, but the ability to handle multiple motor loads simultaneously is reduced
Solution Approach 1:
The inverter employs dynamic phase control that can adjust the phase angles of multiple output channels in real-time. This dynamic capability allows the system to handle multiple motor loads simultaneously with optimized current distribution, while the control complexity is managed through microcontroller-based automation
Solution Approach 2:
The inverter is designed with universal output channels that can independently drive multiple types of motor loads (single-phase, two-phase, three-phase motors) simultaneously. Each channel is equipped with phase control capability that allows it to adapt to different load requirements, providing multi-functionality without proportionally increasing system complexity
Data Source
AI summary
The present invention relates to a multi output inverter that is adapted to supply mains powered appliances 47-49 and/or poly-phase motors 50, 51.