Portable Inverter Power Generation Resonance Speed Control
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Solution Overview
Problem
Portable inverter power generation apparatuses face challenges in suppressing engine resonance noise without imposing a great burden on the engine, particularly due to rapid changes in AC output current, which are not effectively managed by control methods designed for hybrid vehicle electric generators.
Innovation Solution
A portable inverter power generation apparatus with a controller that sets and adjusts the target rotational speed of the engine based on detected AC output current, keeping the engine speed below or above resonance rotational speeds to minimize vibration and noise, while efficiently managing load current changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the rotational speed of the engine is controlled based on AC output current using conventional methods, then the engine can supply suitable current to the load, but engine resonance noise occurs when the rotational speed passes through the resonance region
Solution Approach 1:
The control device causes the engine rotational speed to skip through the resonance region by setting the target rotational speed to values above or below the resonance region, rather than allowing the speed to pass through it. This is achieved by comparing the target rotational speed with the resonance rotational speed and adjusting the target accordingly, thus preventing resonance noise while maintaining rapid response to load changes
Solution Approach 2:
The control device changes the parameter of target rotational speed based on the relationship between load current and resonance rotational speed. When the target speed approaches the resonance region, the control device adjusts the target speed parameter to be above or below the resonance region, thereby eliminating resonance noise while preserving the engine's ability to respond quickly to load current variations
2Object-affected harmful factors
If the target rotational speed is set above or below the resonance region to prevent noise, then engine resonance noise is suppressed, but the engine may be overburdened with rapid load current changes
Solution Approach 1:
The control device dynamically adjusts the target rotational speed based on the direction of speed change and the relationship with resonance rotational speed. When the engine speed is increasing, the target is set above the resonance region; when decreasing, the target is set below the resonance region. This dynamic adjustment prevents resonance noise while considering the engine's current operating state, thereby avoiding excessive burden on the engine
Solution Approach 2:
The control device uses feedback from the engine rotational speed and load current to continuously adjust the target rotational speed. By monitoring whether the current speed is above or below the resonance region and the direction of change, the control device adjusts the target speed to prevent resonance while maintaining smooth operation and avoiding sudden large changes that would burden the engine
3Object-affected harmful factors
If the engine rotational speed changes smoothly as in hybrid vehicle applications, then resonance noise is reduced, but the AC output current may severely increase and decrease in short periods without battery buffering
Solution Approach 1:
The control device segments the rotational speed adjustment process by dividing it into phases before and during passage through the resonance region. By identifying the resonance rotational speed and comparing it with the target speed, the control device creates distinct control regions (above and below resonance) that prevent resonance noise while allowing the engine to respond adequately to load current changes without requiring smooth transitions that would delay response
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 approach effectively prevents engine resonance noise and vibration without overburdening the engine, ensuring efficient operation and stable power output even with rapid changes in load current.
Implementation Method 1
an electric generator arranged to generate AC electric power by the rotation of the engine
Implementation Method 2
a rectifying circuit arranged to convert the AC electric power generated by the electric generator into DC electric power
Implementation Method 3
an inverter circuit arranged to convert the DC electric power obtained by the conversion into AC electric power
Implementation Method 4
a resonance rotational speed at which the engine resonates
Data Source
AI summary
In a portable inverter power generation apparatus, a rectifying circuit converts AC electric power generated by an electric generator into DC electric power, and an inverter circuit converts the DC electric power into AC electric power. A current sensor detects an AC output current from the inverter circuit. In a first case where the AC output current detected by the current sensor increases from a value lower than a first value to a value higher than the first value, a computer sets a target rotational speed to a value lower than a resonance rotational speed at which an engine resonates until the AC output current detected by the current sensor increases to a second value higher than the first value, and sets the target rotational speed to a value higher than the resonance rotational speed when the detected AC output current increases to the second value. In a second case where the AC output current detected by the current sensor decreases from a value higher than the second value to a value lower than the second value, the computer unit sets the target rotational speed to a value higher than the resonance rotational speed until the AC output current detected by the current sensor decreases to the first value, and sets the target rotational speed to a value lower than the resonance rotational speed when the detected AC output current decreases to the first value.