Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a magnetic suspension sensor interference suppression method based on variable step length minimum mean square error, and the method is used for realizing the sensor interference vibration suppression of a magnetic suspension flywheel.
The first technical scheme adopted by the invention is as follows: a magnetic suspension sensor interference suppression method based on variable step length minimum mean square error comprises the following steps:
carrying out stress analysis and modeling on the rotor, and identifying parameters of a rotor magnetic suspension bearing system;
and introducing a variable step size minimum mean square error algorithm and setting a step size factor to suppress interference.
Further, the step of analyzing and modeling the stress of the rotor and identifying the parameters of the rotor magnetic suspension bearing system specifically further comprises:
carrying out stress analysis on the rotor, and obtaining a rotor dynamics equation according to a Newton's law and a Lagrange equation;
constructing a rotor magnetic suspension bearing system model according to a dynamic equation;
and identifying parameters of the rotor magnetic suspension bearing system.
Further, the rotor dynamics equation is formulated as follows:
in the above formula, FAX、FBXFor the electromagnetic force of the rotor in the x-direction, FAY、FBYThe electromagnetic force of the rotor along the y direction, alpha and beta are the angular displacement of the rotor rotating around the x and y axes, omega is the rotating speed, l is the length of the rotor, and m is the mass of the rotor.
Further, the expression of the rotor magnetic suspension bearing system model is as follows:
F=kii+kxx
in the above formula, kiAs a current stiffness system, kxIs the displacement stiffness coefficient.
Further, the parameter for identifying the rotor magnetic suspension bearing system is specifically the displacement stiffness coefficient k of the identification systemxAnd current stiffness coefficient kiThe method specifically comprises the following steps:
horizontally placing the rotor on a test bed and respectively calculating the ratio of the current rigidity coefficient and the displacement rigidity coefficient of the X channel and the Y channel according to the stable suspension of the rotor;
vertically installing a rotor and respectively calculating the current rigidity coefficient and the displacement rigidity coefficient of an X channel and a Y channel according to the stable suspension of the rotor;
and measuring the vertical offset displacement, the horizontal offset displacement, the rotor mass and the vertical angle between the normal direction of the magnetic pole surface and the ground, calculating the current rigidity coefficient and the displacement rigidity coefficient of the X channel, and calculating the current rigidity coefficient and the displacement rigidity coefficient of the Y channel.
Further, the step factor is expressed as follows:
in the above formula, f represents the rotor rotation frequency, μ1' denotes a positive parameter, | e (k) | denotes signal error.
The method and the system have the beneficial effects that: the method identifies the displacement stiffness coefficient and the current stiffness coefficient by establishing a model, introduces a variable step length minimum mean square error algorithm to realize suppression of vibration caused by sensor disturbance, and adopts a variable step length factor which changes along with the change of the rotor displacement signal frequency to realize balance, thereby realizing suppression of sensor disturbance vibration of the magnetic suspension flywheel.
Detailed Description
The invention is described in further detail below with reference to the figures and the specific embodiments. The step numbers in the following embodiments are provided only for convenience of illustration, the order between the steps is not limited at all, and the execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.
The invention provides a magnetic suspension sensor interference suppression method based on variable step length minimum mean square error, which comprises the following steps:
carrying out stress analysis and modeling on the rotor, and identifying parameters of a rotor magnetic suspension bearing system;
and introducing a variable step size minimum mean square error algorithm and setting a step size factor to suppress interference.
Specifically, for different rotation frequencies, a proper step factor needs to be selected to effectively filter the unbalanced interference, so that the fixed-step LMS algorithm can only have a good compensation effect on some fixed rotation frequencies.
Further, as a preferred embodiment of the method, the step of analyzing and modeling the stress of the rotor and identifying the parameters of the rotor magnetic suspension bearing system specifically further includes:
carrying out stress analysis on the rotor, and obtaining a rotor dynamics equation according to a Newton's law and a Lagrange equation;
constructing a rotor magnetic suspension bearing system model according to a dynamic equation;
and identifying parameters of the rotor magnetic suspension bearing system.
Specifically, the force analysis diagram refers to fig. 2.
Further as a preferred embodiment of the method, the rotor dynamics equation has the formula:
in the above formula, FAX、FBXFor the electromagnetic force of the rotor in the x-direction, FAY、FBYThe electromagnetic force of the rotor along the y direction, alpha and beta are the angular displacement of the rotor rotating around the x and y axes, omega is the rotating speed, l is the length of the rotor, and m is the mass of the rotor.
Further as a preferred embodiment of the method, the expression of the rotor magnetic suspension bearing system model is as follows:
F=kii+kxx (2)
in the above formula, kiAs a current stiffness system, kxIs the displacement stiffness coefficient.
In addition, referring to fig. 3, many interference sources exist in the magnetic suspension GMW control system, unbalanced interference force is vibration interference introduced in a rotor dynamics link and is influenced by factors such as a processing technology and installation errors, and interference is also introduced in a sensor measurement link and a magnetic force generation link.
Sensor runout (Sensor disturbance) is expressed in Sensor coordinates as:
in the above formula, i is the harmonic order, i is 1,2, … … n; x is the number ofai,xbiAmplitude of ith harmonic of output signal of sensor at two ends of magnetic bearings A and BValue of thetaai,θbiRespectively, corresponding to the initial phase.
Further as a preferred embodiment of the method, the parameter for identifying the rotor magnetic suspension bearing system is specifically a displacement stiffness coefficient k of the identification systemxAnd current stiffness coefficient kiThe method specifically comprises the following steps:
horizontally placing the rotor on a test bed and respectively calculating the ratio of the current rigidity coefficient and the displacement rigidity coefficient of the X channel and the Y channel according to the stable suspension of the rotor;
vertically installing a rotor and respectively calculating the current rigidity coefficient and the displacement rigidity coefficient of an X channel and a Y channel according to the stable suspension of the rotor;
measuring vertically displaced offset displacement E [ i ]vx(t)]Horizontally placed offset displacement E [ i ]hx(t)]The rotor mass m and the vertical angle theta between the normal direction of the magnetic pole surface and the ground front surface are calculated, and the current rigidity coefficient k of the X channel is calculatedixAnd coefficient of displacement stiffness khxCalculating the current rigidity coefficient k of the Y channeliyAnd coefficient of displacement stiffness khy。
In particular, the coefficient of stiffness k for displacementxAnd current stiffness coefficient kiAnd (5) performing identification. When the rotor is horizontally placed on the test bed, the kinetic equation is:
when the rotor was stably suspended, it was considered that:
taking the average value of two sides of the formula (4):
according to formula (6):
for the X channel, E [ i ] is measuredhx(t)]And E [ x ]h(t)]Then, the ratio of the current stiffness coefficient to the displacement stiffness coefficient can be calculated, and the Y channel is the same as the current stiffness coefficient and the displacement stiffness coefficient.
When the rotor is vertically mounted, the kinetic equation:
when the rotor was stably suspended, it was considered that:
average value of two sides of formula (8)
Due to the existence of the control action, the displacement rigidity force generated by the offset displacement is the same as that generated when the control current is horizontally placed, and the control current additionally comprises a part which is excessive by overcoming the component force of gravity. Subtracting equation (6) from equation (10):
influenced by an integral term in a PID controller, after a displacement offset instruction is given, the final steady-state displacement deviation is 0, the given offset displacement instruction is equal, and the method comprises the following steps:
the following can be obtained:
measured to obtain E [ ivx(t)]、E[ivx(t)]M and theta, k can be calculatedixIn order to improve the accuracy, the average value can be obtained by multipoint measurement, and k can be obtained from the equations (7) and (13)hx。
Further as a preferred embodiment of the method, referring to fig. 3 and fig. 4, a variable step minimum mean square error algorithm is introduced to define x (t) ═ sin (ω)0t) cos(ω0t)]TFor the input signal vector, W (t) ═ wL1(t) wL2(t)]TIs a weight vector, d (t) is a signal to be filtered, Y (t) is an algorithm input signal, e (t) is an error signal, ω is0For filtering angular frequencies, μ is the step size. Then there are:
e(t)=d(t)-Y(t)=d(t)-XT(t)W(t)
Y(t)=Y1(t)wL1(t)+Y2wL2(t)
Wk+1(t)=Wk(t)+μe(t)X(t)
the closed loop transfer function from d (t) to e (t) is known as:
in the above formula, ω0=2πf0T and T are system sampling periods.
To ensure convergence, the step length should satisfy the condition:
zero of the function is
When the frequency f of d (t) is equal to the algorithm input signal frequency f
0When there is H
LWhere (z) ═ 0, filtering of d (t) can be achieved.
Further as a preferred embodiment of the method, for convenient parameter design, an improved variable step length minimum mean square error algorithm is provided, and the step length factor is set as:
in the above formula, f represents the rotor rotation frequency, μ1' denotes a positive parameter, | e (k) | denotes signal error.
A magnetic suspension sensor interference suppression device based on variable step length minimum mean square error comprises:
at least one processor;
at least one memory for storing at least one program;
when the at least one program is executed by the at least one processor, the at least one processor is enabled to implement the method for magnetic levitation sensor interference suppression based on variable step size minimum mean square error as described above.
The contents in the above method embodiments are all applicable to the present system embodiment, the functions specifically implemented by the present system embodiment are the same as those in the above method embodiment, and the beneficial effects achieved by the present system embodiment are also the same as those achieved by the above method embodiment.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.