Stable and passive observer-based V/Hz control for synchronous motors

An electric drive configured to drive a synchronous motor, the electric drive comprising an inverter and a computing device including a processor, and a memory storing instructions for performing an observer-based V/Hz control of the synchronous motor, wherein the instructions, when executed by the processor, cause the computing device to:

• obtain a stator current vector of the synchronous motor;
• estimate, using a state observer, a stator flux linkage vector of the synchronous motor based on the stator current vector, a stator voltage reference vector and a stator angular frequency reference and optionally a control-rotor rotation angle estimated by the state observer, wherein the control-rotor rotation angle is an angle between control coordinates and rotor coordinates and the state observer is a speed-sensorless back-electromotive-force-based state observer defined in the control coordinates and being based on a mathematical model for the synchronous motor;
• perform speed-sensorless state-feedback control based on the estimated stator flux linkage vector, the stator current vector, a stator flux linkage reference vector and the stator angular frequency reference so as to calculate the stator voltage reference vector;
• and
• apply the stator voltage reference vector to the inverter for feeding the synchronous motor.

A method for an observer-based V/Hz control of a synchronous motor, the method comprising:

• obtaining a stator current vector of the synchronous motor;
• estimating, using a state observer, a stator flux linkage vector of the synchronous motor based on the stator current vector, a stator voltage reference vector and a stator angular frequency reference and optionally a control-rotor rotation angle estimated by the state observer, wherein the control-rotor rotation angle is an angle between control coordinates and rotor coordinates and the state observer is a speed-sensorless back-electromotive-force-based state observer defined in the control coordinates and being based on a mathematical model for the synchronous motor;
• performing speed-sensorless state-feedback control based on the estimated stator flux linkage vector, the stator current vector, a stator flux linkage reference vector and the stator angular frequency reference so as to calculate the stator voltage reference vector;
• and
• applying the stator voltage reference vector to an inverter of a drive feeding the synchronous motor.

A computer program product comprising program instructions embodied on a non-transitory computer readable medium for performing an observer-based V/Hz control of a synchronous motor, the performing comprising at least the following steps:

• obtaining a stator current vector of the synchronous motor;
• estimating, using a state observer, a stator flux linkage vector of the synchronous motor based on the stator current vector, a stator voltage reference vector and a stator angular frequency reference and optionally a control-rotor rotation angle estimated by the state observer, wherein the control-rotor rotation angle is an angle between control coordinates and rotor coordinates and the state observer is a speed-sensorless back-electromotive-force-based state observer defined in the control coordinates and being based on a mathematical model for the synchronous motor;
• performing speed-sensorless state-feedback control based on the estimated stator flux linkage vector, the stator current vector, a stator flux linkage reference vector and the stator angular frequency reference so as to calculate the stator voltage reference vector;
• and
• applying the stator voltage reference vector to an inverter of a drive feeding the synchronous motor.