US 8,552,674 B2Granted

Method for control of synchronous electrical motors

OwnerRadek Georgiev Nachev, Blagovest Georgiev Nachevinventors

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Abstract

Method for control of synchronous electrical motors that enables determining the instantaneous motor load angle and rotor speed without using rotor position sensors. The method is realized with solving the set of differential equations that govern the currents in the stator windings of the motor for the time intervals between each two consecutive crossings of the currents in the windings of their set values and deriving relationships between the induced in the windings back-electromotive force voltages and the parameters of the Pulse Width Modulation. The parameters of the Pulse Width Modulation are measured and stored in a memory and based on the derived relationships the values of the back-electromotive force voltages are calculated continuously in time. From the values of the back-electromotive force voltages the motor load angle and rotor speed are calculated and used as feedback signals for the closed-loop control of the motor.

Claims2

Dependent claims

Method for control of synchronous electrical motor, characterized with this, that resistances R, inductances L and the time constants τ=L/R of the motor windings are determined and stored in a memory;

a value of a supply voltage E of the motor is measured and stored in the memory;
durations of time intervals tOFF1 and tOFF2 when the respective windings are short-circuited, and durations of time intervals tON1 and tON2 when the respective windings are connected to the supply source, between each two consecutive crossings of the currents in the windings of their set values are measured and stored in the memory;
the set values I11 and I21 of the currents in the respective windings at the beginning of the time intervals when they are short-circuited, and the set values I12 and I22 of the currents in the respective windings at the end of the time intervals when they are connected to the supply source, are also stored in the memory;
from all the stored values and based on the following formulas the values of the induced in the motor windings back-electromotive force voltages ubemf1 and ubemf2 are calculated:
u
bemf
⁢
⁢
1
=
E
⁡
(
1
-
ⅇ
-
t
ON
⁢
⁢
1
/
τ
)
+
RI
11
⁢
ⅇ
-
(
t
ON
⁢
⁢
1
+
t
OFF
⁢
⁢
1
)
/
τ
-
RI
12
1
-
ⅇ
-
(
t
ON
⁢
⁢
1
+
t
OFF
⁢
⁢
1
)
/
τ
u
bemf
⁢
⁢
2
=
E
⁡
(
1
-
ⅇ
-
t
ON
⁢
⁢
2
/
τ
)
+
RI
21
⁢
ⅇ
-
(
t
ON
⁢
⁢
2
+
t
OFF
⁢
⁢
2
)
/
τ
-
RI
22
1
-
ⅇ
-
(
t
ON
⁢
⁢
2
+
t
OFF
⁢
⁢
2
)
/
τ
from the calculated values of the back-electromotive force voltages ubemf1 and ubemf2, instantaneous values of motor load angle θ and angular rotor speed ω are calculated based on the following formulas:
ubemf1=Um cos β=kω cos β
ubemf2=Um sin β=kω sin β
θ=α−β
where Um is the amplitude of ubemf1 and ubemf2, κ is a motor constant that is determined from the datasheet parameters of the motor, β is the angular position of the rotor with respect to the rotor zero position, α is the angular position of the vector of the stator magnetic field with respect to the rotor zero position;
based on the calculated motor load angle θ and angular rotor speed ω a closed-loop control of the motor is executed.

135 more elements

Method for control of synchronous electrical motor, characterized with this, that resistances R and inductances L of the motor windings are determined and stored in a memory;

a value of a supply voltage E of the motor is measured and stored in the memory;
durations of time intervals tOFF1 and tOFF2 when the respective windings are short-circuited, and durations of time intervals tON1 and tON2 when the respective windings are connected to the supply source, between each two consecutive crossings of the currents in the windings of their set values are measured and stored in the memory;
the set values I11 and I21 the currents in the respective windings at the beginning of the time intervals when they are short-circuited, and the set values I12 and I22 of the currents in the respective windings at the end of the time intervals when they are connected to the supply source, are also stored in the memory;
from all the stored values and based on the following formulas the values of the induced in the motor windings back-electromotive force voltages ubemf1 and ubemf2 are calculated:
u
bemf
⁢
⁢
1
=
E
⁢
⁢
t
ON
⁢
⁢
1
t
ON
⁢
⁢
1
+
t
OFF
⁢
⁢
1
-
RI
11
-
L
⁡
(
I
12
-
I
11
)
t
ON
⁢
⁢
1
+
t
OFF
⁢
⁢
1
u
bemf
⁢
⁢
2
=
E
⁢
⁢
t
ON
⁢
⁢
2
t
ON
⁢
⁢
2
+
t
OFF
⁢
⁢
2
-
RI
21
-
L
⁡
(
I
22
-
I
21
)
t
ON
⁢
⁢
2
+
t
OFF
⁢
⁢
2
from the calculated values of the back-electromotive force voltages ubemf1 and ubemf2, instantaneous values of motor load angle θ and angular rotor speed ω are calculated based on the following formulas:
ubemf1=Um cos β=kω cos β
ubemf2=Um sin β=kω sin β
θ=α−β
where Um is the amplitude of ubemf1 and ubemf2, κ is a motor constant that is determined from the datasheet parameters of the motor, β is the angular position of the rotor with respect to the rotor zero position, α is the angular position of the vector of the stator magnetic field with respect to the rotor zero position;
based on the calculated motor load angle θ and angular rotor speed ω a closed-loop control of the motor is executed.

105 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/692,386Filed 3 Dec 2012 · continuation
Priority: BG 10999715 Nov 2007
Published: US 2013/0113403 A19 May 2013
Granted: 8 Oct 2013
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

H02P 6/08
Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position;…:…
H02P 6/34
Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position;…:…
H02P
Control or regulation of electric motors, electric generators or dynamo-electric converters

Family

Application12/676,362Parent of this continuation · filed 4 Mar 2010
US 2013/0113403 A1Pre-grant publication · published 9 May 2013
US 8,358,092 B2Parent of this continuation
US 2010/0201297 A1Published application
US 8,552,674 B2This patent

From the US filing history. Foreign family members aren’t listed.