Portable Oxygen Concentrator Motor Speed Oscillation Control
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Solution Overview
Problem
Portable oxygen concentrators face challenges in reducing noise and vibration due to the variable torque load caused by the movement of pistons in the compressor, leading to undesirable speed oscillations of the motor.
Innovation Solution
A controller is used to minimize speed oscillations of the motor in the compressor by varying the applied voltage over multiple commutation steps during rotational cycles, based on actual motor speeds and average motor speeds, to reduce differences between the applied motor torque and the variable torque load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compressor with motor and pistons is used to pressurize ambient air, then oxygen concentration capability is improved, but noise and vibration increase due to variable torque load
Solution Approach 1:
The patent applies vibration isolation elements (mounts) between the compressor and the housing to reduce the transmission of vibrations. These mounts are specifically designed to isolate the compressor's vibrations from the overall device structure, directly addressing the noise and vibration problem while maintaining the compressor's oxygen concentration function.
Solution Approach 2:
The patent modifies the operational parameters of the motor by varying the applied voltage over multiple commutation steps during rotational cycles. This voltage variation compensates for the variable torque load caused by piston movement, minimizing speed oscillations and thereby reducing noise and vibration while maintaining effective compression.
2Volume of moving object
If compressor size is reduced for portability, then device portability is improved, but torque load variation increases causing greater speed oscillations
Solution Approach 1:
The patent implements dynamic voltage adjustment during motor operation, varying the applied voltage according to the specific commutation step and rotational cycle. This dynamic control adapts to the changing torque load conditions caused by piston movement, stabilizing motor speed despite the compact compressor design that exacerbates torque variations.
Solution Approach 2:
The patent uses feedback from actual motor speed measurements to determine the voltage pattern for subsequent rotational cycles. By comparing actual motor speeds at each commutation step with average motor speeds, the system adjusts voltage application to minimize speed oscillations, creating a closed-loop control system that stabilizes motor operation.
3Object-affected harmful factors
If voltage is varied over commutation steps to minimize speed oscillations, then noise and vibration are reduced, but control system complexity increases
Solution Approach 1:
The patent determines the voltage pattern during one rotational cycle and applies it in subsequent rotational cycles. This preliminary determination and reuse of voltage patterns reduces the computational burden in real-time control, as the system establishes a reusable voltage schedule rather than continuously recalculating optimal voltage at each commutation step.
Solution Approach 2:
The patent applies voltage variations in a periodic manner synchronized with the motor's rotational cycles and commutation steps. This periodic control approach aligns with the natural operating rhythm of the compressor, allowing the control system to use repeating patterns rather than complex continuous adjustments, thereby reducing control complexity while maintaining effectiveness.
Data Source
AI summary
A portable oxygen concentrator includes a compressor and a controller. The compressor includes a motor, at least one chamber, and at least one piston operably coupled to the motor and movable within the at least one chamber. In some embodiments, the controller is configured to: determine actual motor speeds for commutations steps of the motor during a first rotational cycle; determine an average motor speed during the first rotational cycle; determine a voltage pattern based at least on a comparison of the average motor speed during the first rotational cycle and the actual motor speeds for the commutation steps of the motor during the first rotational cycle; and cause the voltage pattern to be applied to the motor during a second rotational cycle to reduce differences between applied motor torque and variable torque load imparted by the at least one piston.