US2023318508A1PendingUtilityA1
Laundry treating machine and method for operating a laundry treating machine
Est. expiryJul 26, 2038(~12 yrs left)· nominal 20-yr term from priority
H02P 27/08H02P 21/22D06F 34/10D06F 23/02D06F 37/304H02P 21/14D06F 2105/46H02M 1/32H02M 5/458H02P 3/18H02P 21/36D06F 2103/46D06F 2103/24
70
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Claims
Abstract
A laundry machine having a casing, a drum a motor to rotate the drum, and an inverter-based apparatus to control the motor. The inverter-based apparatus comprises: an input stage configured to convert alternating mains voltage to rectified DC voltage, an electrolytic capacitor-less inverter configured to generate output currents to feed to the electric moto based on duty cycles of switching signals, a DC-link connecting the electrolytic capacitor-less inverter to the input stage and crossed by DC-link currents from/towards the electrolytic capacitor-less inverter, a DC-link capacitor connected to the DC-link, a regulator system configured to control duty cycles of switching signals based on determined/estimated motor values indicating a controlled parameter of said motor, and a motor reference value associated to the controlled parameter of the motor, and an active voltage limiter unit configured to regulate the motor reference value to limit the DC-link capacitor voltage within a predetermined voltage range.
Claims
exact text as granted — not AI-modified1 . A method for controlling a laundry treating machine comprising:
a casing, a laundry drum mounted inside said casing to rotate about a rotation axis, an electric motor configured to rotate said laundry drum about said rotation axis, an inverter-based apparatus configured to control said electric motor and comprising:
an input stage configured to be connected to mains lines for receiving AC lines currents and AC mains voltage and configured to convert said alternating mains voltage AC to a rectified DC voltage,
an electrolytic capacitor-less inverter configured to generate output currents to be fed to said electric motor based on duty cycles of switching signals,
a DC-link which connects said electrolytic capacitor-less inverter to said input stage and is crossed by DC-link currents from, or towards, said electrolytic capacitor-less inverter,
a DC-link capacitor connected to said DC-link, and
a regulator system which is configured to control the duty cycles of switching signals based on at least a determined/estimated motor value (Id,Iq),(T) indicative of a controlled parameter of said electric motor, and at least a motor reference value (Idref,Iqref),(Tref), which is associated to said controlled parameter of said electric motor;
wherein the method comprises regulating said motor reference value (Idref,Iqref),(Tref) in order to limit the DC-link capacitor voltage (Vdc(t)) within a predetermined voltage range.
2 . The method according to claim 1 , wherein:
said determined/estimated motor values correspond to said output currents (iu, iv, iw), and said motor reference values correspond to said current references (idref, iqref); and, said method further comprises:
determining the amplitude of said DC-link capacitor voltage (Vdc(t));
determining the amplitude of output currents (iu, iv, iw) provided to said electric motor by said electrolytic capacitor-less inverter;
operating said regulator system to control said duty cycles of the switching units of said electrolytic capacitor-less inverter based on said output currents (iu, iv, iw) and said current references (idref, iqref); and
regulating said current references (idref, iqref) of said regulator system in order to cause said DC-link capacitor voltage (Vdc(t)) to be limited within said predetermined voltage range.
3 . The method according to claim 2 , further comprising regulating said current references (idref, iqref) of said regulator system in order to cause said DC-link capacitor voltage (Vdc(t)) to be limited within said predetermined voltage range, without using said lines currents and/or DC-link currents.
4 . The method according to claim 2 , further comprising clamping said DC-link capacitor voltage (Vdc(t)) to a prefixed value, when said electric motor ( 2 ) regenerates back current to said the DC-link capacitor ( 11 ) via said electrolytic capacitor-less inverter.
5 . The method to according to claim 2 , further comprising:
determining an active current (ia)(iaref) based on said output currents (iu, iv, iw) and said duty cycles; and regulating said current references (idref, iqref) based on said active current (ia)(iaref) and said DC-link capacitor voltage (Vdc(t)).
6 . The method according to claim 5 , further comprising determining a first active current (ia) based on the d-q axis-wise duty cycles (Ud, Uq) which are indicative of said duty cycles of the switching signals and d-q axis-wise currents (id, iq) indicative of said output currents (iu, iv, iw).
7 . The method according to claim 5 , further comprising determining a second active current (iaref) based on the d-q axis-wise duty cycles (Ud, Uq) indicative of said duty cycles of the switching signals and said determined current references (idref, iqref).
8 . The method according to claim 5 , wherein determining said active current (ia(t))(iaref(t)) comprises computing a minimum current (laws) between said first (ia(t)) and second active currents (iaref(t)).
9 . The method according to claim 6 , further comprising determining two maximum absolute correction signals (idmax(t)),(iqmax(t)) on the basis of said second active current (iaref) and said d-q axis-wise duty cycles (Ud, Uq).
10 . The method according to claim 9 , further comprising determining an instantaneous maximum allowable regeneration current (iaIstAbs(t)) based on a measured voltage level and a parameter (iaMaxAbs) indicative of a maximum absolute active current for regeneration.
11 . The method according to claim 10 , wherein determining the instantaneous maximum allowable regeneration current (iaIstAbs(t)) is based on the following equation
i a IstAbs ( t )=ω V ( t ) i a MaxAbs
wherein ω V (t) is a weight coefficient that depends on:
said DC-link capacitor voltage Vdc(t),
a nominal DC-link voltage (Vdcnom), and
a predetermined high-voltage limit (Vhigh).
12 . The method according to claim 11 , further comprising determining a negative fraction of correction to be applied according to an empirical saturated-cubic equation:
ρ
(
t
)
=
sat
[
(
i
a
ws
(
t
)
+
i
a
I
st
Ab
s
(
t
)
i
a
I
st
Ab
s
(
t
)
)
3
]
-
1
0
13 . The method according to claim 12 , further comprising determining unconstrained axis-wise corrections as a fraction of the maximum correction by the following equation:
i d unc ( t )=ρ( t ) i d max ( t )
i q unc ( t )=ρ( t ) i q max ( t )
14 . The method according to claim 13 , further comprising determining constrained axis-wise current corrections by applying the following saturation and correction equations
i
qcorr
(
t
)
=
{
max
(
i
qunc
(
t
)
,
0
)
if
ω
(
t
)
>
0
min
(
i
qunc
(
t
)
,
0
)
if
ω
(
t
)
<
0
i
d
corr
(
t
)
=
min
(
i
d
unc
(
t
)
,
0
)
-
K
qd
abs
(
i
q
corr
(
t
)
-
i
q
unc
(
t
)
)
wherein:
Kqd is a positive tuning gain that usable to transfer to the d-axis part of the correction originally computed for the q-axis, when saturation occurs, and
idunc and iqunc are said axis-wise current corrections.
15 . The method according to claim 14 , further comprising modifying said current references according to the following equations:
i d refMod ( t )= i d ref ( t )+ i d corr ( t ) i q refMod ( t )= i q ref ( t )+ i q corr ( t )
16 . The method according to claim 1 , wherein
said determined/estimated motor values correspond to an estimated torque (T) of said electric motor; said motor reference values correspond to a torque reference (Tref); and the method further comprises:
operating said regulator system to receive said estimated torque (T) and said torque reference (Tref) and control the switching units of said electrolytic capacitor-less inverter based on said estimated torque (T) and said torque reference (Tref), and
regulating said torque reference (Tref) of said regulator system in order to cause said DC-link capacitor voltage (Vdc(t)) to be limited within said predetermined voltage range.
17 . The method according to claim 16 , further comprising regulating said torque reference (Tref) of said regulator system in order to cause said DC-link capacitor voltage (Vdc(t)) to be limited within said predetermined voltage range, without using said lines currents and/or DC-link currents.
18 . The method according to claim 17 , further comprising:
receiving first voltage signals (Uα(t), Uβ(t) indicative of the duty cycles of said switching signals; receiving first current signals (iα(t),iβ(t) indicative of said output currents (iu, iv, iw) provided to said electric motor; receiving said voltage (Vdc(t)) of the DC-link capacitor; and determining a torque limit value (Tref_lim) based on said first voltage signals (Uα(t), Uβ(t), said first current signals (iα(t),iβ(t), and said voltage (Vdc(t)) of the DC-link capacitor.
19 . The method according to claim 18 , further comprising:
determining an active current (ia(t)) based on said first voltage signals (Uα(t), Uβ(t) and said first current signals (iα(t),iβ(t)); determining an instantaneous maximum allowable regeneration current (iaIstAbs(t)) based on the measured voltage level and the prefixed parameter (iaMaxAbs) corresponding to a maximum absolute active current (ia(t)) for regeneration by means of the following equation:
ia Ist Abs( t )=ω V*Ia MaxAbs,
wherein ωV is a weight coefficient that depends on the voltage Vdc(t) and a nominal DC-link voltage Vdcnom and on a highvoltage limit Vhigh;
calculating a current value (Ai) indicative of the difference between said active current (ia(t)) and said maximum allowable regeneration current (iaIstAbs(t)); and performing a proportional-integral function on said current value (Ai) to calculate said torque limit (Tref_lim).
20 . The method according to claim 19 , further comprising:
comparing said torque target (Tt) with said torque limit (Tref_lim); and setting the torque reference (Tref(t)) with the torque limit (Tref_lim(t)), when said motor speed (ω) is positive and said torque target (Tt(t)) is lower or equal to said torque limit (Tref_lim(t)).
21 . The method according to claim 20 , further comprising setting the torque reference (Tref(t)) with the torque limit (Tref_lim(t)), when the motor speed ω is negative and the torque target (Tt(t)) is greater than, or equal to the torque limit (Tref_lim(t)).Join the waitlist — get patent alerts
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