Abstract: Methods and apparatus may implement controlled generation of oxygen enriched air in an oxygen concentrator while implementing control that reduces pneumatic imbalance between the concentrator's canisters, such as dynamic pressure imbalance or other pneumatic characteristic. One or more controllers may regulate operation of a compressor that feeds a pressurised air stream to the concentrator's canisters. This may regulate speed of the compressor to a speed set point for generating the pressurised stream. The regulating may involve generating a compressor control signal having a characteristic parameter such as a power parameter. The controller(s) may operate valve(s) in a cyclic pattern so as to produce oxygen enriched air in an accumulator. A cycle of the cyclic pattern may include a plurality of phases, where each of the plurality of phases has a duration. The controller(s) may then generate a dynamic adjustment to the duration(s) based on an evaluation of the characteristic parameter.

Abstract: Oxygen concentrator methods and apparatus estimate sieve bed effective capacity. Estimation applies function(s) to a parameter of a measured pressure-time characteristic of the bed, characteristic of a phase of an adsorption cycle of the concentrator at a predetermined motor speed of its compression system. Estimation may involve operating the concentrator at a predetermined bed pressure and measuring a mass flow of gas entering or exiting the bed, and may use the measured mass flow and one or more functions. Estimation may involve a measured bed exhaust mass flow for a purge phase when bed pressure is regulated to maintain a predetermined target pressure using motor speed adjustment. The estimation may apply exhaust mass flow function(s) to the measured exhaust mass flow. Estimation of the effective capacity may involve applying motor speed function(s) to measured motor speed, such as an adjusted one for regulating canister pressure to achieve a target pressure.