| US 7,349,814 B2 | ||
| Measurement method and arrangement | ||
| Srikanth Venkatachari, Bangalore (India); Mikael Holmberg, Porvoo (Finland); and Asko Salminen, Espoo (Finland) | ||
| Assigned to ABB Oy,, Helsinki (Finland) | ||
| Appl. No. 10/590,883 PCT Filed Mar. 04, 2005, PCT No. PCT/FI2005/000134 § 371(c)(1), (2), (4) Date Aug. 28, 2006, PCT Pub. No. WO2005/085772, PCT Pub. Date Sep. 15, 2005. |
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| Claims priority of application No. 20040351 (FI), filed on Mar. 04, 2004. | ||
| Prior Publication US 2007/0185661 A1, Aug. 09, 2007 | ||
| Int. Cl. G01F 1/00 (2006.01); G01F 23/00 (2006.01) | ||
| U.S. Cl. 702—50 [702/45; 702/98] | 23 Claims |
| 1. A method for measuring a flow in a pump system, in which a liquid flow is generated by means of a pump and the pump is
actuated by an electric drive, in which the rotation speed of an alternating-current motor is controlled with a control unit,
comprising:
measuring (402) a pump power (P) in the pump system,
measuring a rotation speed (v) of the pump,
measuring (504) a static pressure (Hs),
setting an estimate of a dynamic pressure (Hd) to a pre-estimated constant value,
determining (506) an estimate of a total pressure (H) on the basis of the static pressure, a difference (Δh) of height between static pressure
sensors, and the estimate of the dynamic pressure,
determining a first estimate (410, 416) of the liquid flow on the basis of the measured pump power (P) and rotation speed variables,
determining a second estimate (514, 516) of the liquid flow on the basis of the estimate of a total pressure (H) and rotation speed variables,
determining a flow measurement result by a logical selection or any other predetermined function on said first estimate of
the liquid flow and said second estimate of the liquid flow,
determining (520) a new estimate of a dynamic pressure (Hd) on the basis of the flow measurement result,
re-determining the estimate of a total pressure (H) on the basis of the static pressure, the difference (Δh) of height between
the static pressure sensors, and the new estimate of the dynamic pressure,
re-determining the second estimate of the liquid flow on the basis of the estimate of a total pressure (H) and rotation speed
variables, and
re-determining the flow measurement result by a logical selection or any other predetermined function on said first estimate
of the liquid flow and said second estimate of the liquid flow.
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