US 12,169,033 B2
Methods for controlling and diagnosing an actuator for a low power system
Tom Nøhr Christiansen, Kvistgaard (DK)
Assigned to S-RAIN CONTROL A/S, Kvistgaard (DK)
Appl. No. 17/439,573
Filed by S-RAIN CONTROL A/S, Kvistgaard (DK)
PCT Filed Mar. 12, 2020, PCT No. PCT/EP2020/056717
§ 371(c)(1), (2) Date Sep. 15, 2021,
PCT Pub. No. WO2020/187706, PCT Pub. Date Sep. 24, 2020.
Claims priority of application No. 19163260 (EP), filed on Mar. 15, 2019.
Prior Publication US 2022/0154847 A1, May 19, 2022
Int. Cl. F16K 37/00 (2006.01); F16K 31/06 (2006.01); G05B 15/02 (2006.01); H01F 7/08 (2006.01)
CPC F16K 37/0041 (2013.01) [F16K 31/0644 (2013.01); G05B 15/02 (2013.01); H01F 7/081 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A method of controlling an actuator for an irrigation system, comprising a movable element and an electromagnetic coil for generating a magnetic field for displacing said movable element along the axis of said electromagnetic coil, said movable element comprising a magnetic material, said actuator having an active state and a passive state, said movable element being closer to said electromagnetic coil when said actuator being in said active state than when said actuator being in said passive state, said method comprising the steps:
applying a DC inrush voltage, Vi, to said electromagnetic coil such that a current runs through said electromagnetic coil, whereby the current running through said electromagnetic coil increases until it has reached an inrush steady state current, Is,
optimizing an operational hold voltage, Voper, where optimizing said operational hold voltage, Voper, comprises the steps:
a) applying a hold voltage, Vh, which is lower than said DC inrush voltage, Vi,
b) applying said DC inrush voltage, Vi, to said electromagnetic coil,
c) determining when said movable element moved from said passive state to said active state due to the magnetic field produced by said electromagnetic coil during application of said DC inrush voltage, Vi, in step b), wherein determining when said movable element moved from said passive state to said active state comprises the steps:
retrieving a raise time Ti, where said raise time is the time it takes for the current through said electromagnetic coil, to reach an inrush current, Ii, where said inrush current is equal to said inrush steady state current, Is, or said inrush current is lower than said inrush steady state current,
retrieving a hold current, Ih, where said hold current, Ih, is the steady state current through said electromagnetic coil, when said hold voltage, Vh, is applied to said electromagnetic coil,
retrieving a hold current time, Th, where said hold current time, Th, is the time it takes for the current through said electromagnetic coil to go from zero current to said hold current, Ih, when the inrush voltage, Vi, is applied to said electromagnetic coil,
measuring a test raise time, Ttest, where said test raise time, Ttest, is the time it takes for the current through said electromagnetic coil to go from said hold current, Ih, and to said inrush current, Ii, and
determining that said movable element moved from said passive state to said active state or from said active state to said passive state when the sum of said hold current time, Th, and said test raise time, Ttest, is equal to said raise time, Ti,
d) repeating steps a)-c) to determine one or more values of said hold voltage, Vh, for which said movable element was determined not to have moved and, optionally, one or more values of said hold voltage, Vh, for which said movable element was determined to have moved upon the subsequent application of said DC inrush voltage, Vi,
e) selecting said operational hold voltage, Voper, to have a value equal to or higher than the lowest value of said hold voltage, Vh, for which it was determined that said movable element did not move upon subsequent application of said DC inrush voltage, Vi,
f) applying said operational hold voltage, Voper, to said electromagnetic coil to maintain said movable element in said active state.