Direct torque control of permanent magnet synchronous machines - analysis and implementation
Luukko, Julius (2000-06-30)
Väitöskirja
Luukko, Julius
30.06.2000
Acta Universitatis Lappeenrantaensis
Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:978-952-335-054-0
https://urn.fi/URN:ISBN:978-952-335-054-0
Tiivistelmä
The direct torque control (DTC) has become an accepted vector control method beside
the current vector control. The DTC was first applied to asynchronous machines, and
has later been applied also to synchronous machines. This thesis analyses the application
of the DTC to permanent magnet synchronous machines (PMSM).
In order to take the full advantage of the DTC, the PMSM has to be properly dimensioned.
Therefore the effect of the motor parameters is analysed taking the control principle
into account. Based on the analysis, a parameter selection procedure is presented.
The analysis and the selection procedure utilize nonlinear optimization methods.
The key element of a direct torque controlled drive is the estimation of the stator flux
linkage. Different estimation methods – a combination of current and voltage models
and improved integration methods – are analysed. The effect of an incorrect measured
rotor angle in the current model is analysed and an error detection and compensation
method is presented. The dynamic performance of an earlier presented sensorless flux
estimation method is made better by improving the dynamic performance of the lowpass
filter used and by adapting the correction of the flux linkage to torque changes.
A method for the estimation of the initial angle of the rotor is presented. The method
is based on measuring the inductance of the machine in several directions and fitting the
measurements into a model. The model is nonlinear with respect to the rotor angle and
therefore a nonlinear least squares optimization method is needed in the procedure.
A commonly used current vector control scheme is the minimum current control. In
the DTC the stator flux linkage reference is usually kept constant. Achieving the minimum
current requires the control of the reference. An on-line method to perform the
minimization of the current by controlling the stator flux linkage reference is presented.
Also, the control of the reference above the base speed is considered.
A new estimation flux linkage is introduced for the estimation of the parameters of
the machine model. In order to utilize the flux linkage estimates in off-line parameter
estimation, the integration methods are improved. An adaptive correction is used in
the same way as in the estimation of the controller stator flux linkage. The presented
parameter estimation methods are then used in a self-commissioning scheme.
The proposed methods are tested with a laboratory drive, which consists of a commercial
inverter hardware with a modified software and several prototype PMSMs.
the current vector control. The DTC was first applied to asynchronous machines, and
has later been applied also to synchronous machines. This thesis analyses the application
of the DTC to permanent magnet synchronous machines (PMSM).
In order to take the full advantage of the DTC, the PMSM has to be properly dimensioned.
Therefore the effect of the motor parameters is analysed taking the control principle
into account. Based on the analysis, a parameter selection procedure is presented.
The analysis and the selection procedure utilize nonlinear optimization methods.
The key element of a direct torque controlled drive is the estimation of the stator flux
linkage. Different estimation methods – a combination of current and voltage models
and improved integration methods – are analysed. The effect of an incorrect measured
rotor angle in the current model is analysed and an error detection and compensation
method is presented. The dynamic performance of an earlier presented sensorless flux
estimation method is made better by improving the dynamic performance of the lowpass
filter used and by adapting the correction of the flux linkage to torque changes.
A method for the estimation of the initial angle of the rotor is presented. The method
is based on measuring the inductance of the machine in several directions and fitting the
measurements into a model. The model is nonlinear with respect to the rotor angle and
therefore a nonlinear least squares optimization method is needed in the procedure.
A commonly used current vector control scheme is the minimum current control. In
the DTC the stator flux linkage reference is usually kept constant. Achieving the minimum
current requires the control of the reference. An on-line method to perform the
minimization of the current by controlling the stator flux linkage reference is presented.
Also, the control of the reference above the base speed is considered.
A new estimation flux linkage is introduced for the estimation of the parameters of
the machine model. In order to utilize the flux linkage estimates in off-line parameter
estimation, the integration methods are improved. An adaptive correction is used in
the same way as in the estimation of the controller stator flux linkage. The presented
parameter estimation methods are then used in a self-commissioning scheme.
The proposed methods are tested with a laboratory drive, which consists of a commercial
inverter hardware with a modified software and several prototype PMSMs.
Kokoelmat
- Väitöskirjat [1037]