CN101242151A - Compensation method for levitation hysteresis - Google Patents

Abstract

The invention discloses a compensation method for magnetic levitation hysteresis. The specific steps of the method are: using a sensor to measure the offset; using a controller to generate a differential control signal, and judging the control signal that needs to be demagnetized; The control signal is weighted; the power amplifier is used to generate excitation currents for magnetization and demagnetization respectively; the excitation current makes the increase and decrease of the magnetic induction intensity generated by the differential electromagnet equal. Or in order to increase the compensation coil and the corresponding compensation power amplifier, the increase and decrease of the magnetic induction intensity generated by the differential electromagnet are equal to each other by increasing the compensation current. Adopting the present invention to compensate the hysteresis of the suspension maglev is simple, convenient, stable and reliable, and can make the increase and decrease of the magnetic induction intensity generated by the differential electromagnet equal, make the magnetization and demagnetization synchronized and equal, and ensure that the suspended matter returns to its original state. The balance position improves the stability of the magnetic levitation system.

Description

Compensation method for levitation hysteresis

technical field

The invention relates to the electromagnetic force control of the magnetic levitation, and more specifically, relates to a compensation method for the hysteresis of the magnetic levitation.

Background technique

The working principles of the magnetic levitation bearing and the electromagnetic strip steel stabilization system are basically the same, as shown in Figure 1, the suspended object 1 will deviate from the original equilibrium position under external disturbance, the deviation is measured by the sensors 3a and 3b, and the controller 5 according to The deviation generates differential control signals (u ₀ +Δu) and (u ₀ -Δu), and the power amplifiers 4a and 4b convert the control signals into excitation currents (I ₀ +Δi) and (I ₀ -Δi) of the coils 6a and 6b , the excitation current makes the electromagnets 2a and 2b generate differential magnetic fields respectively, and the suspended object 1 is subjected to the resultant force of the magnetic field in the differential magnetic field, and the direction points to the equilibrium position, so that the suspended object 1 returns to the equilibrium position. But there is hysteresis phenomenon in the actual process, as shown in Figure 2, when the suspended object deviates from the equilibrium position, the current of an electromagnet coil in the differential electromagnet increases by Δi, the corresponding magnetic field intensity increases by ΔH, and the magnetic induction intensity increases ΔB is larger; while the current of the other electromagnet coil decreases Δi, and the corresponding magnetic field strength decreases ΔH. Since the BH characteristic curve is a directional closed curve, the change of magnetic induction B always lags behind the change of magnetic field strength H, so The increase and decrease of B with H are not along the same curve, so the corresponding magnetic induction intensity does not decrease ΔB, but decreases ΔB′. The increase and decrease of magnetic induction intensity are not equal, which will lead to the two differential electromagnets respectively The generated magnetization and demagnetization are not synchronized in phase and have differences in magnitude, resulting in an unequal increase in magnetic force and decrease in magnetic force, which cannot ensure that the suspended object returns to its equilibrium position.

At present, soft magnetic materials with small coercive force and high saturation magnetic flux density are usually used to make differential electromagnets. Due to the small hysteresis loop area of this material and the weakened nonlinearity of B-H characteristics, the differential electromagnets produce The magnetic induction intensity is basically the same, so that the magnetization and demagnetization are also easy to be equal, so this method can meet the hysteresis compensation of most magnetic suspension bearings. However, for magnetic levitation strip steel, etc., due to the large air gap in the magnetic circuit and the nonlinear enhancement of B-H characteristics, it is difficult to ensure that the magnetic induction intensity generated by the differential electromagnet is equal, so that the magnetization and demagnetization are not synchronized and unequal, resulting in the electromagnetic force. The increase and decrease are not equal, and it is impossible to ensure that the suspended object returns to the equilibrium position, thereby increasing the difficulty of control and reducing the stability of the magnetic levitation system.

Contents of the invention

Aiming at the disadvantages in the prior art that the magnetization and demagnetization generated by the above-mentioned differential electromagnets are not synchronized and unequal, it is impossible to ensure that the suspended matter returns to the equilibrium position, which increases the difficulty of control and reduces the stability of the magnetic levitation. The present invention The purpose of the invention is to provide a compensation method for magnetic levitation hysteresis, which is simple and convenient, and can enhance the stability of the magnetic levitation system.

To achieve the above object, the present invention adopts the following technical solutions:

Option 1, the compensation method for the levitation hysteresis includes the following steps:

A. Use the sensor to measure the offset;

B. Use the controller to generate differential control signals and judge the control signals that need to be demagnetized;

C. weighting the control signal that needs to be demagnetized generated in step B;

D. Use a power amplifier to generate excitation currents that generate magnetization and demagnetization respectively;

E. The excitation current generated in step D makes the increase and decrease of the magnetic induction generated by the differential electromagnet equal.

Preferably, the weighting process in step C is to multiply the control signal by a weighting factor.

Preferably, the calculation steps of the weighting factor are as follows:

C1. Draw the magnetization B-H characteristic curve of the core material of the differential electromagnet;

C2. Linearize the magnetization B-H characteristic curve at the static operating point to obtain the slopes of magnetization and demagnetization of the differential electromagnet respectively;

C3. Calculate the weighting factor.

Preferably, the formula for calculating the weighting factor in step C3 is:

$\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="k"\; filenames="A20071003719700101.png,A20071003719700121.png"\; state="\{\{state\}\}">k</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ></span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

Among them, k is a weighting factor, k ₁ is the magnetic slope of the iron core, and k ₂ is the demagnetization slope of the iron core;

Preferably, the increase and decrease of the excitation current for magnetization and demagnetization in step D are different.

Scheme 2, the specific steps of the compensation method for the suspension magnetic levitation hysteresis are as follows:

A. Add compensation coils and corresponding compensation power amplifiers to the two differential electromagnets;

B. Use the sensor to measure the offset;

C. Use the controller to generate differential control signals and judge the control signals that need to be demagnetized;

D. Use the controller to generate a compensation signal;

E. Use the corresponding compensation power amplifier to convert the compensation signal generated in step D into the compensation current of the compensation coil;

F. The compensation current generates compensation electromagnetic induction, so that the increase and decrease of the magnetic induction intensity generated by the differential electromagnet are equal.

Preferably, the calculation steps of the compensation current in D of the step are as follows:

D1. Draw the magnetization B-H characteristic curve of the core material of the differential electromagnet;

D2. Linearize the magnetization B-H characteristic curve at the static operating point to obtain the slopes of magnetization and demagnetization of the differential electromagnet respectively;

D3. Calculate the compensation current.

Preferably, the calculation formula of the compensation current in D3 of the step is:

${\mathrm{<span\; class="notranslate">\; \&Delta;i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; \&Delta;i</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="k"\; filenames="A20071003719700101.png,A20071003719700121.png"\; state="\{\{state\}\}">k</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ></span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

Among them, Δi' is the compensation current, k ₁ is the magnetic slope of the iron core, k ₂ is the demagnetization slope of the iron core, and Δi is the increment of the excitation current of the corresponding differential electromagnet.

Preferably, the direction of the compensation current is opposite to that of the exciting current of the corresponding differential electromagnet.

In the above-mentioned technical solution, the compensation method of the magnetic levitation hysteresis of the present invention uses the sensor to measure the offset; uses the controller to generate the differential control signal, and judges the control signal that needs to be demagnetized; weights the control signal that needs to be demagnetized Processing; use the power amplifier to generate excitation currents that generate magnetization and demagnetization respectively; the excitation current makes the increase and decrease of the magnetic induction intensity generated by the differential electromagnet equal. The compensation method for magnetic levitation hysteresis of the present invention also adds compensation coils and corresponding compensation power amplifiers on the two differential electromagnets; uses sensors to measure offsets; uses controllers to generate differential control signals, and judges A control signal for demagnetization is required; use a controller to generate a compensation signal; use a corresponding compensation power amplifier to convert the compensation signal generated in step D into a compensation current for the compensation coil; the compensation current generates a compensation electromagnetic induction, so that the differential electromagnet produces The increase of magnetic induction is equal to the decrease. Adopting the present invention to compensate the hysteresis of the suspension maglev is simple, convenient, stable and reliable, and can make the increase and decrease of the magnetic induction intensity generated by the differential electromagnet equal, make the magnetization and demagnetization synchronized and equal, and ensure that the suspended matter returns to its original state. The balance position improves the stability of the magnetic levitation system.

Description of drawings

Fig. 1 is a schematic diagram of the working principle of the prior art magnetic levitation;

Fig. 2 is a schematic diagram of the B-H characteristic curve of the prior art magnetic levitation;

Fig. 3 is a schematic diagram of the principle of scheme one of the present invention;

Fig. 4 is a schematic block diagram of a process flow of scheme one of the present invention;

Fig. 5 is the B-H characteristic curve schematic diagram of scheme one of the present invention;

6 is a schematic diagram of the second scheme of the present invention;

Fig. 7 is a schematic block diagram of the second scheme of the present invention;

Fig. 8 is a schematic diagram of the B-H characteristic curve of the second solution of the present invention.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example 1

The method of weighting the control signal that needs to be demagnetized is adopted, that is, the software method.

Please combine with Figure 3 and Figure 4, when the suspended object 1 deviates from the original equilibrium position under external disturbance, use the sensors 3a and 3b to measure the deviation, and then use the controller 5 to generate a differential control signal according to the deviation ( u ₀ +Δu) and (u ₀ -Δu), from which it is judged that the control signal that needs to be demagnetized is (u ₀ -Δu), and the control signal (u ₀ -Δu) is weighted, and multiplied by a weighting factor k to obtain (u ₀ -kΔu) control signal, use the power amplifier 4a to convert the control signal (u ₀ +Δu) into the excitation current (I ₀ +Δi) of the coil 6a, use the power amplifier 4b to convert the control signal (u ₀ -kΔu) Converted into the excitation current (I ₀ -kΔi) of the coil 6b, please combine it as shown in Figure 5, due to the increase Δi of the magnetic induction intensity of the differential electromagnet 2a that needs to be magnetized and the magnetic induction of the differential electromagnet 2b that needs to be demagnetized If the reduction of the intensity kΔi is not equal, the increase and decrease of the generated electromagnet magnetic induction intensity can be equal to ΔB, so that the magnetization and demagnetization generated by the two differential electromagnets 2a and 2b are synchronized in phase and in phase. The magnitudes are equal, so that the increase and decrease of the electromagnetic force of the differential electromagnet are equal to ensure that the suspended object 1 returns to the equilibrium position. Please refer to Figure 5 again, the calculation steps of the weighting factor k are as follows: first, through experimental research, draw the magnetization BH characteristic curve of the iron suspension material of the differential electromagnet, and then linearize the magnetization BH characteristic curve at the static operating point , respectively obtain the slope k ₁ of magnetization and the slope k ₂ of demagnetization of the differential electromagnet, and finally calculate the weighting factor k through the calculation formula. The formula used to calculate the weighting factor k is $k=\frac{k_1}{k_2}$ , where k is a weighting factor, k ₁ is the magnetic slope of the iron core, k ₂ is the demagnetization slope of the iron core, and the magnetic addition slope k ₁ is greater than the demagnetization slope k ₂ .

Example 2

The method of increasing the compensation current by adding compensation coils and corresponding compensation power amplifiers is the hardware method.

Please combine with Fig. 6 and Fig. 7, add a compensation coil 7a and a compensation power amplifier 4c corresponding to the compensation coil 7a on the differential electromagnet 2a; Coil 7b correspondingly compensates power amplifier 4d. When the suspended object 1 deviates from the original equilibrium position under external disturbance, use the sensors 3a and 3b to measure the deviation, and then use the controller 5 to generate differential control signals (u ₀ +Δu) and (u ₀ - Δu), from which it is judged that the control signal that needs to be demagnetized is (u ₀ -Δu), and the power amplifiers 4a and 4b are used to convert the control signals (u ₀ +Δu) and (u ₀ -Δu) into the excitation of the coils 6a and 6b respectively current (I ₀ +Δi) and (I ₀ -Δi); then use the controller 5 to generate a compensation signal Δu', and use the corresponding compensation power amplifier 4d to convert the compensation signal Δu' into compensation on the electromagnet 2b that needs to be demagnetized The compensation current Δi′ of the coil 7b, since the direction of the compensation current Δi′ is opposite to that of the excitation current (I ₀ -Δi) of the corresponding differential electromagnet 2b, please combine it with Fig. 8, the compensation current Δi′ generates a compensation electromagnetic induction, which is convenient The increase and decrease of the generated electromagnet magnetic induction can be equal to ΔB, so that the reduction of the magnetic induction of the electromagnet 2b that needs to be demagnetized is equal to the increase of the magnetic induction of the magnetized electromagnet 2a, so that the two differential The magnetization and demagnetization produced by the electromagnets 2a and 2b are synchronized in phase and equal in size, so that the increase and decrease of the electromagnetic force of the differential electromagnet are equal to ensure that the suspended object 1 returns to the equilibrium position. Please refer to Figure 8 again, the calculation steps of the compensation current Δi′ are as follows: first, through experimental research, draw the magnetization BH characteristic curve of the iron core material of the differential electromagnet, and then linearize the magnetization BH characteristic curve at the static operating point Processing, the slope k ₁ of magnetization and the slope k ₂ of demagnetization of the differential electromagnet are respectively obtained, and finally the compensation current Δi′ is calculated through the calculation formula. The formula used to calculate the compensation current Δi' is ${\mathrm{\&Delta;i}}^{\&prime;}=\frac{k_1-k_2}{k_2}\mathrm{\&Delta;i},$ Among them, Δi' is the compensation current, k ₁ is the magnetization slope of the iron core, k ₂ is the demagnetization slope of the iron core, Δi is the increment of the excitation current of the corresponding differential electromagnet, and the magnetization slope k ₁ is greater than the demagnetization slope k ₂ .

The magnetic levitation hysteresis compensation method of the present invention is simple and convenient to use, stable and reliable, through the compensation of the excitation current or the method of increasing the compensation current, the magnetic induction intensity generated by the differential electromagnet can be increased and decreased by the same magnitude, so that the increase The magnetism and demagnetization are synchronized and equal, which ensures that the suspended object in the suspension maglev system returns to the equilibrium position in high-precision applications, and improves the stability of the maglev system.

Claims (9)

1. A compensation method for magnetic levitation hysteresis, characterized in that, The specific steps of the method are as follows: A. Use the sensor to measure the offset; B. Use the controller to generate differential control signals and judge the control signals that need to be demagnetized; C. weighting the control signal that needs to be demagnetized generated in step B; D. Use a power amplifier to generate excitation currents that generate magnetization and demagnetization respectively; E. The excitation current generated in step D makes the increase and decrease of the magnetic induction generated by the differential electromagnet equal. 2. the compensation method of magnetic levitation hysteresis as claimed in claim 1, is characterized in that, The weighting process in step C is to multiply the control signal by a weighting factor. 3. the compensation method of magnetic levitation hysteresis as claimed in claim 2, is characterized in that, The calculation steps of the weighting factor are as follows: C1. Draw the magnetization B-H characteristic curve of the core material of the differential electromagnet; C2. Linearize the magnetization B-H characteristic curve at the static operating point to obtain the slopes of magnetization and demagnetization of the differential electromagnet respectively; C3. Calculate the weighting factor. 4. the compensation method of magnetic levitation hysteresis as claimed in claim 3, is characterized in that, The calculation formula of the weighting factor in the step C3 is: $\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ></span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$ Among them, k is the weighting factor, k ₁ is the magnetic slope of the iron core, and k ₂ is the demagnetization slope of the iron core. 5. the compensation method of suspension maglev hysteresis as claimed in claim 1, is characterized in that, The increase and decrease of the excitation current for magnetization and demagnetization in step D are different. 6. A compensation method for magnetic levitation hysteresis, characterized in that, The specific steps of the method are as follows: A. Add compensation coils and corresponding compensation power amplifiers to the two differential electromagnets; B. Use the sensor to measure the offset; C. Use the controller to generate differential control signals and judge the control signals that need to be demagnetized; D. Use the controller to generate a compensation signal; E. Use the corresponding compensation power amplifier to convert the compensation signal generated in step D into the compensation current of the compensation coil; F. The compensation current generates compensation electromagnetic induction, so that the increase and decrease of the magnetic induction intensity generated by the differential electromagnet are equal. 7. the compensation method of suspension maglev hysteresis as claimed in claim 6, is characterized in that, The calculation steps of the compensation current in D of the step are as follows: D1. Draw the magnetization B-H characteristic curve of the core material of the differential electromagnet; D2. Linearize the magnetization B-H characteristic curve at the static operating point to obtain the slopes of magnetization and demagnetization of the differential electromagnet respectively; D3. Calculate the compensation current. 8. the compensation method of suspension maglev hysteresis as claimed in claim 7, is characterized in that, The calculation formula of the compensation current in D3 of the step is: $\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}\mathrm{<span\; class="notranslate">\; \&Delta;i</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ></span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$ Among them, Δi' is the compensation current, k ₁ is the magnetic slope of the iron core, k ₂ is the demagnetization slope of the iron core, and Δi is the increment of the excitation current of the corresponding differential electromagnet. 9. The compensation method of the suspension magnetic levitation hysteresis as described in any one of claim 6-8, it is characterized in that: The direction of the compensation current is opposite to that of the exciting current of the corresponding differential electromagnet.

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