Inverter Sleep Control Using Load Response Frequency Check
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Solution Overview
Problem
Inverter systems controlling multiple motors face inefficiencies in energy management, particularly when loads are sensitive to changes, leading to repeated sleep and wake operations and potential abnormal modes due to inappropriate sleep and wake levels.
Innovation Solution
A method for controlling an inverter that checks if the load amount has reduced below a sleep level and verifies if a sleep delay has passed, then varies the motor's operating frequency to determine if the load requires normal operation or sleep mode, preventing errors from no-load operations and optimizing energy usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the inverter enters sleep mode when load amount is below sleep level, then energy consumption is reduced, but repeated sleep and wake operations occur when loads are sensitive to changes, causing system instability and potential abnormal modes
Solution Approach 1:
The patent applies preliminary action by implementing a sleep delay timer before transitioning to sleep mode. When the load amount falls below the sleep level, the system does not immediately enter sleep mode but waits for a predetermined delay period to confirm sustained low load conditions. This preliminary waiting action prevents premature sleep transitions that would cause repeated wake-sleep cycles in load-sensitive scenarios, thereby maintaining system stability while still enabling energy savings.
2Ease of operation
If the inverter uses a simple sleep level threshold for mode transition, then control simplicity is maintained, but inappropriate sleep and wake levels cause repeated operations and errors in load-sensitive scenarios
Solution Approach 1:
The patent enhances the simple threshold-based control by adding a preliminary delay confirmation step. The sleep delay timer acts as a buffer that verifies whether the load remains below the threshold for a sustained period before triggering mode transition. This preliminary verification maintains the simplicity of threshold-based control while eliminating the instability caused by transient load fluctuations, thus resolving the contradiction between ease of operation and reliability.
3Speed
If the inverter immediately transitions to sleep mode when load is low, then energy saving responsiveness is improved, but errors from no-load operations occur due to premature sleep mode entry
Solution Approach 1:
The patent resolves the contradiction between fast response and safe operation by introducing a sleep delay timer as a preliminary confirmation mechanism. When load drops below the sleep level, the system initiates a delay period before actual sleep mode transition. This preliminary delay is brief enough to maintain fast overall response while long enough to ensure load conditions are truly sustained, preventing premature sleep entry that would cause no-load operation errors.
Data Source
AI summary
A method for controlling an inverter in a system including a load, a motor for driving the load, and an inverter for operating the motor comprises when a load amount of the load is reduced to below a sleep level, checking whether a time corresponding to a sleep delay has lapsed; when the load amount of the load is still below the sleep level even after the sleep delay, varying an operating frequency of the motor, and if there is no change in a feedback from the load in response to the variation in the operating frequency, controlling the inverter to enter a sleep mode.