摘要:
A method for determining a change in a mass of a fan impeller. The method includes inducing a torque to the fan impeller and determining a change in the angular speed of the fan impeller, induced by the torque. A value for a first parameter representing a present mass of the fan impeller is determined on the basis of the change in the angular speed and the torque. The change in the mass is then determined on the basis of the first parameter and a second parameter representing the reference mass of the fan impeller.
摘要:
A method for determining a change in a mass of a fan impeller. The method includes inducing a torque to the fan impeller and determining a change in the angular speed of the fan impeller, induced by the torque. A value for a first parameter representing a present mass of the fan impeller is determined on the basis of the change in the angular speed and the torque. The change in the mass is then determined on the basis of the first parameter and a second parameter representing the reference mass of the fan impeller.
摘要:
A method of correcting the stator flux estimate midpoint in alternating-current systems, the method comprising the step of determining a stator flux estimate (&PSgr;s, est?). The method is characterized in steps of forming the sum of the squares of the rectangular components (&PSgr;sx, est?, &PSgr;sy, est?) of the stator flux estimate to obtain a reference variable (k), low-pass filtering the reference variable (k) in order to obtain a low-frequency component (kfilt) of reference variable, subtracting the low-frequency component (kfilt) from the reference variable (k) in order to obtain a difference variable (e), determining rectangular correction term components (&PSgr;sx, corr?, &PSgr;sy, corr?) of the stator flux estimate (&PSgr;s, est?) by multiplying the difference variable (e) by the rectangular components (&PSgr;sx, est?, &PSgr;sy, est?) of the stator flux and a correction coefficient (K&PSgr;corr), and forming a midpoint-corrected stator flux estimate (&PSgr;s, fin?) by adding the correction term components to the components of the stator flux estimate.
摘要:
The invention relates to a method of correcting the flux midpoint in flux-controlled alternating current systems, the method comprising the steps of determining a stator flux estimate (&psgr;s,est) and determining the magnitude of stator current (is). The method is characterized by the steps of forming the scalar product between the stator flux estimate (&psgr;s,est) and the stator current (is) in order to obtain a reference variable (k), low-pass filtering the reference variable (k) in order to obtain a low-frequency component (kfilt) of the reference variable (k), subtracting the low-frequency component (kfilt) from the reference variable (k) in order to obtain a difference variable (e), determining correction term components (&psgr;s,x,corr, &psgr;s,y,corr) of the staror flux estimate (&psgr;s,est) by multiplying the difference variable (e) by the components (&psgr;s,x,est, &psgr;s,y,est) of the stator flux and correction coeficient (K&psgr;corr), and forming a stator flux (&psgr;s,fin) with a corrected midpooint on the basis of the components (&psgr;s,x,est, &psgr;s,y,est) of the stator flux estimate and correction term components (&psgr;s,x,corr, &psgr;s,y,corr).
摘要:
A method for controlling an electrical machine while it is connected to an inverter comprising phase-specific switching components generating an output voltage, an optimum switching table arranged to select a switching combination for the switching components on the basis of the stator flux and torque of the electrical machine, the method comprising steps of defining the stator current vector (is) of the electrical machine, and determining the rotation speed of the electrical machine. The method also comprises the step of defining a switching combination for the switching components on the basis of the stator current vector (is) and stator current reference vector (&psgr;s, ref) of the electrical machine when the determined rotation speed is lower than a predefined limit.