A method for improving the efficiency of an electromagnetic acoustic source using permanent magnets and a transducer made by the method

Abstract

The application discloses a method for improving the efficiency of an electromagnetic sound source by using a permanent magnet and a transducer manufactured by the method, and relates to the field of acoustics. The method comprises the following steps: step one, determining a static working point of a high driving force current ratio according to a driving force-driving current model of a "pot type" non-permanent magnet electromagnetic transducer, and designing direct current excitation; step two, adding a suitable permanent magnet according to the designed direct current excitation to generate a bias magnetic field; step three, equivalently adding a direct current excitation current according to the bias magnetic field of the permanent magnet; step four, determining influencing factors of the driving force current ratio according to a driving force-driving current model of a "pot type" permanent magnet electromagnetic transducer; step five, using a finite element method to optimize parameters with the motor conversion efficiency as an optimization target; and step six, calculating the driving force current ratio. The application has the effect of improving the motor conversion efficiency of the electromagnetic sound source.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of acoustics, in particular to a method for improving the efficiency of an electromagnetic sound source using a permanent magnet and a transducer made by the method. BACKGROUND

[0002] The electromagnetic transducer forms a magnetic circuit under the magnetic conduction of the magnetic yoke and the armature, and generates an electromagnetic force on the armature, which in turn drives the armature to vibrate.

[0003] Under certain structural dimensions, the drive force-current ratio of the electromagnetic transducer increases with the increase of input current; this shows that the electromagnetic transducer has higher motor efficiency under high-power driving, while under low-power driving, the drive force-current ratio of the electromagnetic transducer is very small, which shows that the electromagnetic transducer is not conducive to improving the motor efficiency under low-power driving.

[0004] The current electromagnetic transducer driving technology at least has the following problems: low-frequency electromagnetic sound sources are mostly large-power and wide-band sound sources, and their electro-acoustic conversion efficiency is not high, which cannot meet the demand of long-time work under some limited power supply conditions; especially when the driving current is small, the electro-acoustic conversion efficiency is low. SUMMARY

[0005] In order to improve the electro-acoustic conversion efficiency, the present application provides a method for improving the efficiency of an electromagnetic sound source using a permanent magnet and a transducer made by the method.

[0006] In a first aspect,

[0007] The method for improving the efficiency of an electromagnetic sound source using a permanent magnet provided by the present application adopts the following technical solution:

[0008] A method for improving the efficiency of an electromagnetic sound source using a permanent magnet, comprising the following steps:

[0009] Step one, determine the static working point of high driving force-current ratio according to the driving force-driving current model of the "pot type" non-permanent magnet electromagnetic transducer, and design direct current excitation;

[0010] Step two, add a suitable permanent magnet according to the designed direct current excitation to generate a bias magnetic field;

[0011] Step three, add direct current excitation current equivalent to the bias magnetic field of the permanent magnet;

[0012] Step four, determine the influencing factors of the driving force-current ratio according to the driving force-driving current model of the "pot type" permanent magnet electromagnetic transducer;

[0013] Step five, use the finite element method to optimize the parameters with the motor conversion efficiency as the optimization target;

[0014] Step six, calculate the driving force current ratio.

[0015] By adopting the above technical scheme, the existing "pot type" non-permanent magnet electromagnetic transducer is improved, a permanent magnet is added on the basis of the existing "pot type" non-permanent magnet electromagnetic transducer, the permanent magnet generates a bias magnetic field in the "pot type" non-permanent magnet electromagnetic transducer, direct current excitation bias is introduced, the static operating point of the transducer is adjusted, and the conversion efficiency is improved; the driving mode of the permanent magnet avoids the copper loss and mutual inductance influence introduced by directly adding the direct current excitation, and can adjust the driving force current ratio; under the same structure parameters, when the driving current is less than 500mA, the method can improve the driving force current ratio by more than 3 times, thereby greatly improving the motor conversion efficiency, especially in the case of small current, the motor conversion efficiency is remarkable, and can reach 84.43%; the transducer designed by the method has the characteristics of high driving force current ratio and high motor efficiency under low-power driving of the electromagnetic sound source, and can effectively improve the motor efficiency of the electromagnetic sound source.

[0016] Optionally, in step one, a driving force-driving current model of the "pot type" non-permanent magnet electromagnetic transducer is established, and the driving force current ratio

[0017]

[0018] N is the number of turns, μ0 is the air permeability, S is the equivalent magnetic pole area, d is the air gap height, F m is the driving force, I m is the driving current.

[0019] Among them,

[0020]

[0021] S1 is the annular area of the magnetic yoke, and S2 is the circular area of the magnetic yoke pot core column.

[0022] By adopting the above technical scheme, the driving force-driving current model of the permanent magnet electromagnetic transducer is established, the driving force current ratio is determined, and the static operating point of the high driving force current ratio is determined, so that the direct current excitation process is facilitated.

[0023] Optionally, in step four, a driving force-driving current model of the permanent magnet electromagnetic transducer is established, and the driving force current ratio

[0024]

[0025] N is the number of turns, μ0 is the air permeability, S is the equivalent magnetic pole area.

[0026] Among them,

[0027]

[0028] S1 is the annular area of the magnetic yoke, S2 is the circular area of the magnetic yoke tank core column, μ r is the relative permeability of the permanent magnet, d is the air gap height, F m is the driving force, I m is the driving current, σ is the thickness of the permanent magnet, H c is the coercive force of the permanent magnet material.

[0029] By adopting the above technical scheme, the driving force-driving current model of the permanent magnet electromagnetic transducer is established, and the influencing factors of the driving force current ratio are determined according to the driving force-driving current model of the "tank type" permanent magnet electromagnetic transducer. The subsequent improvement needs to be made to the influencing factors determined by the good driving force current ratio, which narrows the parameter range selected for subsequent improvement, and facilitates the design process.

[0030] Optionally, in step five, the finite element simulation optimizes the permanent magnet thickness, air gap height and tank core column radius contained in the driving force-driving current model.

[0031] By adopting the above technical scheme, the influencing factors of the driving force current ratio determined in step four, that is, the influencing factors that need to be optimized in step four include the permanent magnet thickness, air gap height and tank core column radius. By optimizing these influencing parameters, the influence of the influencing parameters is reduced, thereby improving the sound-electric conversion efficiency.

[0032] Optionally, in step one, the coil winding on the center tank core column of the "tank type" non-permanent magnet electromagnetic transducer fills the magnetic yoke gap.

[0033] By adopting the above technical scheme, the transducer is improved on this basis, which facilitates the subsequent design process.

[0034] The second aspect,

[0035] The application also provides a transducer made by a method of improving the efficiency of an electromagnetic sound source by using a permanent magnet, which comprises a permanent magnet, an armature, a coil, a magnetic yoke and a tank core column.

[0036] By adopting the above technical scheme, by adding a certain thickness of permanent magnet on the center column of the magnetic yoke of the "tank type" electromagnetic transducer, direct current excitation bias is introduced, and the static operating point of the transducer is adjusted, thereby improving the conversion efficiency.

[0037] Optionally, the radius of the permanent magnet is the same as the radius of the center tank core column of the magnetic yoke, and the two are coaxially arranged.

[0038] By adopting the technical scheme, the permanent magnet is coaxially arranged with the center pot core column of the magnetic yoke, the driving mode using the permanent magnet avoids the copper loss of the direct current coil and the mutual inductance influence caused by directly adding the direct current excitation, and the driving force current ratio can be adjusted.

[0039] Optionally, the transducer is a semi-closed rotary body structure.

[0040] By adopting the technical scheme, the semi-closed rotary body structure has the characteristics of less magnetic leakage and high magnetic symmetry, and the conversion efficiency is further improved.

[0041] In summary, the present application has at least one of the following beneficial technical effects:

[0042] 1. The existing "pot type" non-permanent magnet electromagnetic transducer is improved, a permanent magnet is added on the basis of the existing "pot type" non-permanent magnet electromagnetic transducer, the permanent magnet generates a bias magnetic field in the "pot type" non-permanent magnet electromagnetic transducer, direct current excitation bias is introduced, the static operating point of the transducer is adjusted, and the conversion efficiency is improved; the driving mode using the permanent magnet avoids the copper loss of the direct current coil and the mutual inductance influence caused by directly adding the direct current excitation, and the driving force current ratio can be adjusted; under the same structure parameters, when the driving current is less than 500 mA, the proposed method can increase the driving current ratio by more than 3 times, and the smaller the driving current, the more obvious the driving force current ratio and efficiency advantage of adding the permanent magnet, thereby greatly improving the motor conversion efficiency, especially in the case of small current, the motor conversion efficiency is remarkable, which can reach 84.43%; the transducer related to the method has the characteristics of high driving force current ratio and high motor efficiency under low-power driving of the electromagnetic sound source, and the motor efficiency of the electromagnetic sound source can be effectively improved;

[0043] 2. By reasonably designing the direct current excitation, the driving force current ratio can be improved to improve the efficiency, and the driving force current ratio is basically not affected by the driving current within a certain driving current range; using the permanent magnet to realize the direct current excitation can avoid the copper loss of the direct current coil and the influence of mutual inductance;

[0044] 3. Compared with the non-permanent magnet electromagnetic transducer, the present application retains the basic structure and performance of the transducer, and greatly improves the electromechanical conversion efficiency under low-power driving of the electromagnetic sound source only by adding the permanent magnet. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a method step diagram for improving the efficiency of the electromagnetic sound source of the present embodiment;

[0046] Figure 2 is a structure schematic diagram of the permanent magnet electromagnetic transducer of the present embodiment;

[0047] Figure 3is a driving force-driving current curve diagram of a non-permanent magnetic electromagnetic transducer of the embodiment;

[0048] Figure 4 is a driving force-driving current ratio simulation comparison result of the embodiment and a traditional electromagnetic transducer.

[0049] Label explanation: 1, permanent magnet; 2, armature; 3, coil; 4, pot core column. DETAILED DESCRIPTION

[0050] The following will be combined with the Figures 1-4 The application is further described in detail.

[0051] The embodiment of the application discloses a method for improving the efficiency of an electromagnetic sound source by using a permanent magnet. Figures 1-4 , a method for improving the efficiency of an electromagnetic sound source by using a permanent magnet comprises the following steps:

[0052] Step one, according to the driving force-driving current model of the "pot type" non-permanent magnetic electromagnetic transducer, determine the static working point of the high driving force current ratio, design the direct current excitation;

[0053] Step two, according to the designed direct current excitation, add a suitable permanent magnet to generate a bias magnetic field;

[0054] Step three, according to the bias magnetic field of the permanent magnet, equivalently add the direct current excitation current;

[0055] Step four, according to the driving force-driving current model of the "pot type" permanent magnetic electromagnetic transducer, determine the influencing factors of the driving force current ratio;

[0056] Step five, use the finite element method to optimize the parameters with the motor conversion efficiency as the optimization target;

[0057] Step six, calculate the driving force current ratio.

[0058] Refer to Figure 1 In step one, the driving force-driving current model of the "pot type" non-permanent magnetic electromagnetic transducer, that is, the driving force current ratio

[0059]

[0060] N is the number of turns, μ0 is the air permeability, S is the equivalent magnetic pole area, d is the air gap height, F m is the driving force, I m is the driving current.

[0061] Among them,

[0062]

[0063] S1 is the annular area of the magnetic yoke, and S2 is the circular area of the magnetic yoke core column.

[0064] Referring to Figures 1-4 In step two, direct current excitation is added to the "pot type" non-permanent magnetic electromagnetic transducer, and the driving force-driving current curve obtained according to the driving force-driving current model in step one is used to move the working point of the non-permanent magnetic electromagnetic transducer back and forth between points c and a.

[0065] The direct current excitation current is added to move the static working point from the origin to point b in the figure, and the alternating current with an input amplitude of I m will generate a driving force with an amplitude of F m ;

[0066] At this time, the driving force current ratio will be the tangent slope of point b on the curve, and the inclination angle θ2 is greater than θ1. The driving force current ratio under direct current bias is higher than that without bias.

[0067] At the same time, the driving force current ratio is independent of the input current size and is related to the static working point. The higher the static working point, the greater the driving force current ratio.

[0068] Referring to Figures 1-4 , the permanent magnet provides a bias magnetic field in the magnetic circuit, which is equivalent to adding a direct current excitation current, that is, adding a permanent magnet with the same radius on the magnetic yoke core column of the "pot type" non-permanent magnetic electromagnetic transducer, and using the permanent magnet to provide a bias magnetic field in the magnetic circuit.

[0069] The bias magnetic field of the permanent magnet is equivalent to adding a direct current excitation current I0, which avoids the copper loss of the direct current coil and the mutual inductance influence of the direct current coil and the driving coil.

[0070] In step four, the driving force-driving current model of the permanent magnetic electromagnetic transducer is established, that is, the driving force current ratio

[0071]

[0072] N is the number of turns, μ0 is the air permeability, and S is the equivalent magnetic pole area.

[0073] Among them,

[0074]

[0075] S1 is the annular area of the magnetic yoke, S2 is the circular area of the magnetic yoke core column, μ r is the relative permeability of the permanent magnet, d is the air gap height, F m is the driving force, I m is the driving current, σ is the thickness of the permanent magnet, and H c is the coercive force of the permanent magnet material.

[0076] Reference Figures 1-4 In step five, the key parameters are designed according to the following... Figure 3 The permanent magnet electromagnetic transducer structure shown is combined with the driving force-driving current model in step four. Finite element simulation is used to optimize the permanent magnet thickness, air gap height and core column radius included in the driving force-driving current model to improve the efficiency of the electromagnetic sound source. The optimized transducer motor efficiency simulation value can reach 84.43%.

[0077] Reference Figures 1-4 In step six, the driving force-current ratio is calculated. Under the same structural parameters, the driving force-current ratio of a traditional electromagnetic transducer and a permanent magnet electromagnetic transducer is simulated. Simultaneously, the driving force-current ratio is calculated using the formulas from steps one and four. The results are as follows: Figure 4 As shown.

[0078] Under the same structural parameters, when the driving current is less than 500mA, the ratio of driving force to current with the addition of a permanent magnet is ( Figure 4 The slope of the curve is more than three times that of the traditional model, and the smaller the driving current, the more obvious the driving force-current ratio and efficiency advantage of adding permanent magnets.

[0079] Secondly,

[0080] This application also discloses a transducer manufactured using a method of improving the efficiency of an electromagnetic sound source by utilizing permanent magnets, namely a "can-shaped" permanent magnet electromagnetic transducer, see reference. Figures 1-4 The transducer includes a permanent magnet 1, an armature 2, a coil 3, and a yoke. The radius of the permanent magnet 1 is the same as the radius of the central core column 4 of the yoke, and the two are placed coaxially. The transducer has a semi-enclosed rotating structure. That is, the permanent magnet 1 is added to the core column 4 of the "can-shaped" electromagnetic transducer, which is filled with the coil 3 winding on the central core column 4 to fill the gap of the yoke, to introduce magnetic bias and form a permanent magnet electromagnetic drive. By using the permanent magnet 1 on the core column 4 to provide bias magnetic force for the "can-shaped" electromagnetic transducer in the magnetic circuit, the static operating point of the transducer is adjusted, the driving force-current ratio is improved, and thus the efficiency of the electromagnetic sound source is improved. At the same time, while using the permanent magnet 1 to provide bias magnetic field in the magnetic circuit, the copper loss of the DC coil 3 caused by the addition of the DC coil 3 and the mutual inductance between the DC coil 3 and the driving coil 3 are avoided, further improving the conversion efficiency.

[0081] The implementation principle of the method for improving the efficiency of an electromagnetic sound source by using a permanent magnet and the transducer made by the method is as follows: a permanent magnet 1 with a certain thickness is added to the magnetic yoke tank core column 4 of a "tank type" electromagnetic transducer to introduce a permanent magnetic sound source driving mode with static magnetic force bias; the driving force current ratio can be improved by reasonably designing the direct current excitation, thereby improving the efficiency, and the driving force current ratio is basically not affected by the driving current within a certain driving current range; the use of the permanent magnet 1 to realize the direct current excitation can avoid the copper loss of the direct current coil 3 and the influence of mutual inductance; compared with a non-permanent magnetic electromagnetic transducer, the application retains the basic structure and performance of the transducer, and only by adding the permanent magnet 1, the electromechanical conversion efficiency of the low-power electromagnetic sound source under small power driving is greatly improved; under the same structural parameters, when the driving current is less than 500 mA, the driving force current ratio of the transducer with the permanent magnet 1 is more than 3 times that of the original model, and the smaller the driving current, the more obvious the advantages of the driving force current ratio and the efficiency of the transducer with the permanent magnet 1.

[0082] The above are preferred embodiments of the application, and do not limit the protection scope of the application, so: any equivalent changes made in the structure, shape, principle of the application should be covered within the protection scope of the application.

Claims

1. A method for improving the efficiency of an electromagnetic sound source using a permanent magnet, characterized in that, Includes the following steps: Step 1: Determine the static operating point with a high driving force-current ratio based on the driving force-driving current model of the "can-type" non-permanent magnet electromagnetic transducer, and design DC excitation. Step 2: Add a suitable permanent magnet according to the designed DC excitation to generate a bias magnetic field; Step 3: Apply DC excitation current equivalent to the bias magnetic field of the permanent magnet; Step 4: Determine the influencing factors of the driving force-driving current ratio based on the driving force-driving current model of the "can-type" permanent magnet electromagnetic transducer; Step 5: Optimize parameters using the finite element method with motor conversion efficiency as the optimization objective; Step 6: Calculate the driving force-current ratio; In step one, a driving force-driving current model is established for the "can-shaped" non-permanent magnet electromagnetic transducer, where the driving force-current ratio is... ； The number of coil turns. air permeability, The equivalent magnetic pole area, The air gap height, As the driving force, For driving current; in, ； Let be the annular area of ​​the magnetic yoke. Let be the circular area of ​​the magnetic yoke core column. As the driving force, For driving current; In step four, a driving force-driving current model for the permanent magnet electromagnetic transducer is established, where the driving force-current ratio is... ； The number of coil turns. air permeability, This represents the equivalent magnetic pole area; in, ； Let be the annular area of ​​the magnetic yoke. Let be the circular area of ​​the magnetic yoke core column. As the driving force, For driving current, For the thickness of the permanent magnet, The coercivity of the permanent magnet material.

2. The method for improving the efficiency of an electromagnetic sound source using a permanent magnet according to claim 1, characterized in that: In step five, finite element simulation optimizes the permanent magnet thickness, air gap height, and core column radius included in the driving force-driving current model.

3. The method for improving the efficiency of an electromagnetic sound source using a permanent magnet according to claim 1, characterized in that: In step one, the coil winding on the central core column of the "can-shaped" non-permanent magnet electromagnetic transducer fills the magnetic yoke gap.

4. A transducer manufactured using the method of improving the efficiency of an electromagnetic sound source by utilizing a permanent magnet as described in claim 1, characterized in that: The transducer includes a permanent magnet (1), an armature (2), a coil (3), a yoke, and a core column (4).

5. The transducer according to claim 4, characterized in that: The radius of the permanent magnet (1) is the same as the radius of the central core column (4) of the magnetic yoke, and the two are placed coaxially.

6. The transducer according to claim 4, characterized in that: The transducer has a semi-enclosed rotating body structure.

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