US6448735B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Controller for a wound rotor slip ring induction machine
Assignee: ABB Industry Oy
•
Filing: 2001-04-26
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Granted: 2002-09-10
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Expires: 2021-04-26
Abstract
Abstract The direct torque control (DTC) principle is used to control the torque of a wound ring rotor slip induction machine, also known as a doubly fed or cascade machine, by utilizing a solid state inverter on the rotor side. In addition, the DTC principle is used to control the power factor at the stator terminals of the doubly fed machine to a desired level and also to perform the task of synchronization of stator voltage to the grid voltage. An integrated controller is used to implement these three functions.
Inventors
- 👤 Kalyan P. Gokhale
- 👤 Douglas W. Karraker
- 👤 Samuli J. Heikkilä
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:37
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/05; H02P21/00; H02P21/24; H02P21/28; H02P21/30; H02P23/00; H02P23/30
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
118 words
A method for controlling the torque and power factor of a doubly fed machine using direct torque control, comprising the steps of: (a) calculating the estimated torque of said machine; (b) determining a torque error from said estimated torque and a reference torque; (c) calculating the desired rotor flux command Ψr_ref; (d) calculating the actual rotor flux Ψr; (e) converting said actual rotor flux from the stator reference frame to the rotor reference frame by multiplying Ψr by e −jθm ; (f) determining a flux error from said desired rotor flux command and said actual rotor flux converted to the rotor reference frame; and (g) selecting an inverter voltage vector from said torque error and said flux error.
Claim 2
Independent Claim
118 words
A method for controlling the torque and power factor of a doubly fed machine using direct torque control, comprising the steps of: (a) calculating the estimated torque of said machine; (b) determining a torque error from said estimated torque and a reference torque; (c) calculating the desired rotor flux command Ψr_ref; (d) calculating the actual rotor flux Ψr; (e) converting said actual rotor flux from the stator reference frame to the rotor reference frame by multiplying Ψr by e −jθm ; (f) determining a flux error from said desired rotor flux command and said actual rotor flux converted to the rotor reference frame; and (g) selecting an inverter voltage vector from said torque error and said flux error.
Claim 3
Dependent Claim
27 words
The method of claim 1 wherein said estimated torque is calculated as the cross product of the stator flux vector and the stator current of said machine.
Claim 4
Dependent Claim
104 words
The method of claim 1 wherein Ψr_ref is calculated from the equation: ψ r_ref = - l · Torque * ψ g - j · ( Lr M · ψ g + Torque * ψ g · 1 - ( pf * ) 2 pf * ) where l is the leakage reactance, Torque* is the given torque command, pf* is the desired power factor, Ψg is the grid flux vector, and Lr is the rotor inductance and M is the mutual inductance of said doubly fed machine.
Claim 5
Dependent Claim
108 words
The method of claim 1 wherein Ψr_ref is calculated from the equation: ψ r_ref = - l · Torque * ψ g - j · ( Lr M · ψ g + var * ψ g · ω e ) where l is the leakage reactance, Torque* is the given torque command, var* are volt-amperes reactive, we is the electrical frequency of the stator of said doubly fed machine, Ψg is the grid flux vector, and Lr is the rotor inductance and M is the mutual inductance of said doubly fed machine.
Claim 6
Dependent Claim
99 words
The method of claim 1 wherein Ψr is calculated from the equation: ψ r = M Ls ψ s + LsLr - M 2 Ls Ir = M Ls ( ψ s + l · Ir ) where l is the leakage reactance, Ψr and Ψs are the rotor and stator flux vectors of said doubly fed machine, Ir and Is are the rotor and stator currents of said doubly fed machine, and Ls, Lr and M are the stator, rotor and mutual inductances of said doubly fed machine.
Claim 7
Dependent Claim
45 words
The method of claim 1 wherein said estimated torque is calculated as the cross product as one half of the sum of the stator flux vector of said machine and the grid flux vector of said electrical grid, and the stator current of said machine.
Claim 8
Independent Claim
190 words
A method for synchronizing a doubly fed machine having an induced stator voltage using direct torque control to an electrical grid having a grid voltage by controlling the tangential motion and radial length of a flux vector for the rotor of said machine, comprising the steps of: (a) determining the stator flux vector from said induced stator voltage; (b) determining the grid flux vector from said grid voltage; (c) calculating the angular error between said stator flux vector and said grid flux vector; (d) comparing said angular error to zero to determine an error signal for controlling said rotor flux vector tangential motion; (e) calculating the desired rotor flux command Ψr_ref; (f) calculating the actual rotor flux Ψr; (g) converting said actual rotor flux from the stator reference frame to the rotor reference frame by multiplying Ψr by e −jθm ; and (h) determining a flux error from said desired rotor flux command and said actual rotor flux converted to the rotor reference frame, said flux error for controlling said rotor flux vector radial length; and (i) selecting an inverter voltage vector from said torque error and said flux error.
Claim 9
Independent Claim
190 words
A method for synchronizing a doubly fed machine having an induced stator voltage using direct torque control to an electrical grid having a grid voltage by controlling the tangential motion and radial length of a flux vector for the rotor of said machine, comprising the steps of: (a) determining the stator flux vector from said induced stator voltage; (b) determining the grid flux vector from said grid voltage; (c) calculating the angular error between said stator flux vector and said grid flux vector; (d) comparing said angular error to zero to determine an error signal for controlling said rotor flux vector tangential motion; (e) calculating the desired rotor flux command Ψr_ref; (f) calculating the actual rotor flux Ψr; (g) converting said actual rotor flux from the stator reference frame to the rotor reference frame by multiplying Ψr by e −jθm ; and (h) determining a flux error from said desired rotor flux command and said actual rotor flux converted to the rotor reference frame, said flux error for controlling said rotor flux vector radial length; and (i) selecting an inverter voltage vector from said torque error and said flux error.
Claim 10
Dependent Claim
35 words
The method of claim 7 wherein said angular error between said stator flux vector and said grid flux vector is calculated from the cross product of said stator flux vector and said grid flux vector.
Claim 11
Dependent Claim
46 words
The method of claim 7 wherein Ψr_ref is calculated from the equation: ψ r_ref = Lr M ψ g where Lr and M are the rotor and mutual inductances of said doubly fed machine and Ψg is said grid flux vector.
Claim 12
Dependent Claim
99 words
The method of claim 7 wherein Ψr is calculated from the equation: ψ r = M Ls ψ s + LsLr - M 2 Ls Ir = M Ls ( ψ s + l · Ir ) where l is the leakage reactance, Ψr and Ψs are the rotor and stator flux vectors of said doubly fed machine, Ir and Is are the rotor and stator currents of said doubly fed machine, and Ls, Lr and M are the stator, rotor and mutual inductances of said doubly fed machine.
Claim 13
Dependent Claim
44 words
The method of claim 7 further comprising the step of connecting said doubly fed machine to said electrical grid when said rotor flux vector radial length and tangential motion are the same as the radial length and tangential motion of said grid flux vector.
Claim 14
Independent Claim
167 words
A method for synchronizing a doubly fed machine having an induced stator flux vector using direct torque control to an electrical grid having a grid flux vector by controlling the tangential motion and radial length of a rotor flux vector for said machine, comprising the steps of: (a) calculating the angular error between said stator flux vector and said grid flux vector; (b) comparing said angular error to zero to determine an error signal for controlling said rotor flux vector tangential motion; (c) calculating the desired rotor flux command Ψr_ref; (d) calculating the actual rotor flux; (e) converting said actual rotor flux from the stator reference frame to the rotor reference frame by multiplying Ψr by e −jθm ; (f) determining a flux error from said desired rotor flux command and said actual rotor flux converted to the rotor reference frame, said flux error for controlling said rotor flux vector radial length; and (g) selecting an inverter voltage vector from said torque error and said flux error.
Claim 15
Independent Claim
167 words
A method for synchronizing a doubly fed machine having an induced stator flux vector using direct torque control to an electrical grid having a grid flux vector by controlling the tangential motion and radial length of a rotor flux vector for said machine, comprising the steps of: (a) calculating the angular error between said stator flux vector and said grid flux vector; (b) comparing said angular error to zero to determine an error signal for controlling said rotor flux vector tangential motion; (c) calculating the desired rotor flux command Ψr_ref; (d) calculating the actual rotor flux; (e) converting said actual rotor flux from the stator reference frame to the rotor reference frame by multiplying Ψr by e −jθm ; (f) determining a flux error from said desired rotor flux command and said actual rotor flux converted to the rotor reference frame, said flux error for controlling said rotor flux vector radial length; and (g) selecting an inverter voltage vector from said torque error and said flux error.
Claim 16
Dependent Claim
35 words
The method of claim 12 wherein said angular error between said stator flux vector and said grid flux vector is calculated from the cross product of said stator flux vector and said grid flux vector.
Claim 17
Dependent Claim
46 words
The method of claim 12 wherein Ψr_ref is calculated from the equation: ψ r_ref = Lr M ψ g where Lr and M are the rotor and mutual inductances of said doubly fed machine and Ψg is said grid flux vector.
Claim 18
Dependent Claim
100 words
The method of claim 12 wherein Ψr is calculated from the equation is: ψ r = M Ls ψ s + LsLr - M 2 Ls Ir = M Ls ( ψ s + l · Ir ) where l is the leakage reactance, Ψr and Ψs are the rotor and stator flux vectors of said doubly fed machine, Ir and Is are the rotor and stator currents of said doubly fed machine, and Ls, Lr and M are the stator, rotor and mutual inductances of said doubly fed machine.
Claim 19
Dependent Claim
44 words
The method of claim 12 further comprising the step of connecting said doubly fed machine to said electrical grid when said rotor flux vector radial length and tangential motion are the same as the radial length and tangential motion of said grid flux vector.
Claim 20
Dependent Claim
51 words
The method of claim 12 wherein said machine has an induced stator voltage and said electrical grid has a grid voltage and said method further comprises the step of integrating said induced stator voltage to obtain said stator flux vector and integrating said grid voltage to obtain said grid flux vector.
Claim 21
Dependent Claim
163 words
In a controller for controlling the torque and power factor of a doubly fed machine using direct torque control, a method comprising the steps of: selecting either a first operating mode of said controller for controlling the torque and power factor of said machine or a second operating mode of said controller for synchronizing said machine to an electrical grid; said method comprising when said first operating mode is selected the further steps of: calculating the estimated torque of said machine; determining a torque error from said estimated torque and a reference torque; calculating the desired rotor flux command Ψr_ref; calculating the actual rotor flux Ψr; converting said actual rotor flux from the stator reference frame to the rotor reference frame by multiplying Ψr by e −jθm ; determining a flux error from said desired rotor flux command and said actual rotor flux converted to the rotor reference frame; and selecting an inverter voltage vector from said torque error and said flux error.
Claim 22
Dependent Claim
163 words
In a controller for controlling the torque and power factor of a doubly fed machine using direct torque control, a method comprising the steps of: selecting either a first operating mode of said controller for controlling the torque and power factor of said machine or a second operating mode of said controller for synchronizing said machine to an electrical grid; said method comprising when said first operating mode is selected the further steps of: calculating the estimated torque of said machine; determining a torque error from said estimated torque and a reference torque; calculating the desired rotor flux command Ψr_ref; calculating the actual rotor flux Ψr; converting said actual rotor flux from the stator reference frame to the rotor reference frame by multiplying Ψr by e −jθm ; determining a flux error from said desired rotor flux command and said actual rotor flux converted to the rotor reference frame; and selecting an inverter voltage vector from said torque error and said flux error.
Claim 23
Dependent Claim
48 words
The method of claim 18 wherein said estimated torque of said machine is calculated as the cross product of the one-half of the sum of the stator flux vector of said machine and the grid flux vector of said electrical grid, and the stator current of said machine.
Claim 24
Dependent Claim
104 words
The method of claim 18 wherein Ψr_ref is calculated from the equation: ψ r_ref = - l · Torque * ψ g - j · ( Lr M · ψ g + Torque * ψ g · 1 - ( pf * ) 2 pf * ) where l is the leakage reactance, Torque* is the given torque command, pf* is the desired power factor, Ψg is the grid flux vector, and Lr is the rotor inductance and M is the mutual inductance of said doubly fed machine.
Claim 25
Dependent Claim
108 words
The method of claim 18 wherein Ψr_ref is calculated from the equation: ψ r_ref = - l · Torque * ψ g - j · ( Lr M · ψ g + var * ψ g · ω e ) where l is the leakage reactance, Torque* is the given torque command, var* are volt-amperes reactive, ωe is the electrical frequency of the stator of said doubly fed machine, Ψg is the grid flux vector, and Lr is the rotor inductance and M is the mutual inductance of said doubly fed machine.
Claim 26
Dependent Claim
99 words
The method of claim 18 wherein Ψr is calculated from the equation: ψ r = M Ls ψ s + LsLr - M 2 Ls Ir = M Ls ( ψ s + l · Ir ) where l is the leakage reactance, Ψr and Ψs are the rotor and stator flux vectors of said doubly fed machine, Ir and Is are the rotor and stator currents of said doubly fed machine, and Ls, Lr and M are the stator, rotor and mutual inductances of said doubly fed machine.
Claim 27
Dependent Claim
162 words
The method of claim 18 wherein said machine has an induced stator flux vector and said electrical grid has a grid flux vector and said machine is synchronized to said grid by controlling the tangential motion and radial length of a rotor flux vector for said machine, said method comprising when said second operating mode is selected the further steps of: calculating the angular error between said stator flux vector and said grid flux vector; comparing said angular error to zero to determine an error signal for controlling said rotor flux vector tangential motion; calculating the desired rotor flux command Ψr_ref; calculating the actual rotor flux Ψr; converting said actual rotor flux from the stator reference frame to the rotor reference frame by multiplying Ψr by e −jθm ; and determining a flux error from said desired rotor flux command and said actual rotor flux converted to the rotor reference frame, said flux error for controlling said rotor flux vector radial length.
Claim 28
Dependent Claim
42 words
The method of claim 23 wherein when said second operating mode is selected said angular error between said stator flux vector and said grid flux vector is calculated from the cross product of the stator flux vector and the grid flux vector.
Claim 29
Dependent Claim
53 words
The method of claim 23 wherein when said second operating mode is selected Ψr_ref is calculated from the equation: ψ r_ref = Lr M ψ g where Lr and M are the rotor and mutual inductances of said doubly fed machine and Ψg is said grid flux vector.
Claim 30
Dependent Claim
106 words
The method of claim 23 wherein when said second operating mode is selected Ψr is calculated from the equation: ψ r = M Ls ψ s + LsLr - M 2 Ls Ir = M Ls ( ψ s + l · Ir ) where l is the leakage reactance, Ψr and Ψs are the rotor and stator flux vectors of said doubly fed machine, Ir and Is are the rotor and stator currents of said doubly fed machine, and Ls, Lr and M are the stator, rotor and mutual inductances of said doubly fed machine.
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