Electricity: motive power systems – Motor-reversing – Periodic- or intermittent-reversing
Reissue Patent
1992-02-18
2001-09-11
Ro, Bentsu (Department: 2837)
Electricity: motive power systems
Motor-reversing
Periodic- or intermittent-reversing
C318S132000, C318S254100, C318S443000
Reissue Patent
active
RE037360
ABSTRACT:
This invention relates to electronic controls for electric motors, laundry machines including such controls and/or methods of operating said controls.
It is an object of the present invention to provide an electronic motor control for controlling electric motors and/or a laundry machine including such controls and/or a method of operating
a
laundry machine using such controls which will at least provide the public with a useful choice.
Accordingly in one aspect the invention may broadly be said to consist
in
of
a method of cyclically reversing an electronically commutated motor having a plurality of windings on a stator and a rotor having magnetic poles rotatable relative to said stator and using electronic control apparatus and means to indicate the position of the rotor, said method comprising the steps of
(a) Initiating and then continuing a correct sequence of commutations for a desired time or desired number of commutations,
(b) Removing all power from the windings and allowing the rotor to coast towards zero rotation,
(c) Testing the position of the rotor relative to the stator, and
(d) When the rotor is in condition to be reversed and its position relative to the stator is known, changing the sequence of commutations to cause the rotor to change direction
the
to
correct commutations following automatically to maintain rotor rotation in the changed direction, and repeating the steps to give cyclical reversal for a desired time.
In a further aspect the invention consists in control apparatus for an electronically commutated motor having a plurality of windings on a stator adapted to be selectively commutated and a rotor having magnetic poles rotatable relative to said stator said control apparatus comprising:
(a) Timing means to time the period of rotation or counting means to count the number of rotations of the rotor in a desired direction,
(b) Commutation switching means to disconnect power from said windings to allow the rotor to run down towards zero rotation,
(c) Detecting means to indicate rotor position relative to said stator, and
(d) Pattern reverse means operable in response to a signal from said detecting means when the rotor is in condition to be reversed to cause the control signals to cause commutation changes which cause said rotor to change direction without testing for rotor direction.
In a still further aspect the invention consists
in
of
a method of cyclically controlling the supply of power to an electric motor having a rotor said method including the steps of starting rotation of said rotor in one direction setting an initial “power on” time during which power is applied to said motor, switching off power at the end of said initial “power on” time, causing the rotor to slow until in a condition to be reversed, checking the ramp down time the rotor takes to slow to a condition ready for reversal, causing reversal of direction of rotation of said rotor, as soon as the rotor is in condition to be reversed, and repeating the said steps as desired.
In a still further aspect the invention consists in a method of cyclically controlling the supply of power to an electric motor having a rotor said method including the steps of setting a desired time of rotation of said rotor in one direction starting rotation of said rotor in said one direction setting an initial “power on” time during which power is applied to said motor, switching off power at the end of said initial “power on” time, causing the rotor to slow until in a condition to be reversed, checking the ramp down time to rotor takes to slow to a condition ready for reversal, causing reversal of direction of rotation of said rotor, applying power to said rotor for a further “power on” time which is such that said further “power on” time plus said ramp down time equals said desired time, switching off power to said rotor at the end of said further “power on” time, again checking the next ramp down time reversing direction of the rotor to said one direction when said rotor is in condition for reversal and applying power to said rotor for a still further “power on” time which is such that said still further “power on” time plus said next down ramp time equals said desired time and repeating the cycles for a desired length of time, adjusting the “power on” time at desired intervals of time so that the adjusted “power on” time for a further half cycle plus the down ramp time for a previous half cycle equals said desired time.
In a still further aspect the invention consists in a method of electronically cyclically controlling the supply of power to an electric motor said method including the steps of setting a desired speed of rotation of the rotor of the motor, sensing the resistance to rotation of the motor and using responses from the sensing means to actuate adjustment means to adjust the power supplied to the motor to change the motor speed towards said desired speed and then operate the motor within a range of speeds at or close to said desired speed of rotation, switching off the supply of power to the motor, stopping its rotation and then repeating the cycle of operations with the motor running in the reverse direction.
In a still further aspect the invention consists in an electrical control means for cyclically controlling the supply of electrical power to an electric motor having a rotor said control means comprising switching means to switch power to said motor on and off, coasting timing means to time the length of time said rotor takes from the time power is switched off thereto to the time when said rotor is in condition for reversal of direction of rotation, and reversing means to reverse the direction of said rotor when said rotor is in condition for reversing and to switch on said switching means when reversing is to be effected.
In a still further aspect the invention consists in an electronic control means for cyclically controlling the supply of electrical power to an electric motor said electronic control means including setting means operable to set a desired speed of rotation of the rotor of said motor, sensing means to sense resistance to rotation of the motor and adjustment means responsive to said sensing means to adjust the power supplied to the motor to accelerate said motor towards the desired speed and to then operate the motor within a range of speeds at or close to said desired speed of rotation, switching means to switch off the supply of said motor after a desired time and reversing means operable after the motor has substantially stopped to cause the cycle of operating to be repeated with the motor running in the reverse direction.
In a still further aspect the invention consists in an electrical control means for cyclically controlling the supply of electrical power to an electric motor having a rotor said control means comprising switching means to switch power to said motor on and off, power timing means to time the length of power time when power is switched on, coasting timing means to time the length of time said rotor takes from the time power is switched off thereto to the time when said rotor is in condition for reversal of direction of rotation, stroke timing means to time the stroke time during which said rotor rotates between reversals setting means to set said stroke timing means to a desired stroke time, algebraic subtracting means to
algebracially
algebraically
subtract a previous coast time from said stroke time to arrive at a time setting for said power time and reversing means to reverse the direction of said rotor when said rotor is in condition for reversing and to switch on said switching means when reversing is to be effected.
In a still further aspect the invention consists in a method of operating a laundry machine having a container for a wash load of soiled fabrics in wash water and a reciprocable agitator in said container and an electric motor driving said agitator, said method comprising the steps of starting rotation of said motor in one direction setting an initial “power on” time during which power is applied to said motor
Christie Parker & Hale LLP
Fisher & Paykel
Ro Bentsu
LandOfFree
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