CN108412731A - A kind of stroke evaluation method and device for Linearkompressor - Google Patents

Abstract

The present invention provides a kind of stroke evaluation method for Linearkompressor, the Linearkompressor includes linear electric machine, and linear electric machine includes the coil for driving mover to move in a straight line, and is included the following steps：During mover moves to reversed maximum travel position from positive maximum travel position, the counter electromotive force of coil is obtained, and generate the characteristic value of the counter electromotive force；When determining that the characteristic value is less than preset value, increases the power of the linear electric machine, otherwise, reduce the power of the linear electric machine.So as to be accurately controlled the stroke of Linearkompressor.

Description

A stroke estimation method and device for a linear compressor

technical field

The invention relates to the technical field of refrigeration equipment, in particular to a stroke estimation method and device for a linear compressor.

Background technique

The linear compressor is a promising compressor in the field of refrigerators. During the working process of the linear compressor, a power will be set for the linear compressor, which makes the stroke of the linear compressor within a reasonable range, but During the operation of the refrigerator, the suction and exhaust pressure of the system will change (that is, fluctuate). It is understandable that if the suction and exhaust pressure changes, the stroke will fluctuate. When the limit value is exceeded, it is easy to hit the exhaust valve. Or there are problems such as abnormal impact noise; on the contrary, the stroke becomes smaller. It can be seen that during the operation of the linear compressor, it is necessary to perform stroke protection (that is, to control the output power of the linear motor) to prevent the stroke from exceeding the limit value, and to make quick actions against sudden system fluctuations or working condition drifts. Protect linear motors.

Therefore, how to control the stroke of the linear compressor becomes an urgent problem to be solved.

Contents of the invention

The object of the present invention is to provide a stroke estimation method and device for a linear compressor.

In order to achieve one of the objectives of the above invention, an embodiment of the present invention provides a stroke estimation method for a linear compressor, the linear compressor includes a linear motor, and the linear motor includes a coil for driving the mover to move linearly , comprising the following steps: during the process of moving the mover from the forward maximum travel position to the reverse maximum travel position, obtaining the counter electromotive force of the coil, and generating the characteristic value of the counter electromotive force; determining that the characteristic value is less than the preset When the value is , increase the power of the linear motor, otherwise, decrease the power of the linear motor.

As a further improvement of an embodiment of the present invention, the generation of the characteristic value of the counter electromotive force includes: Among them, E(t) is the counter electromotive force, t is the time variable, and E(t) is proportional to Acos(t), A is the maximum stroke during the movement of the mover from the forward maximum stroke position to the reverse maximum stroke position, The moment when the mover is at the maximum stroke position in the forward direction ≤ T ₁ ≤ _{T 2} ≤ The time when the mover is at the maximum stroke position in the reverse direction.

As a further improvement in an embodiment of the present invention, the generation of the eigenvalue of the back electromotive force includes: eigenvalue=|E(t)|, wherein E(t) is the back electromotive force, t is a time variable, E(t ) is not equal to zero and is proportional to Acos(t), A is the maximum travel of the mover in the process of moving from the forward maximum travel position to the reverse maximum travel position, and the moment when the mover is at the forward maximum travel position≤t≤mover The moment at the reverse maximum travel position.

As a further improvement of an embodiment of the present invention, the generation of the characteristic value of the counter electromotive force includes: Where E(t) is the back electromotive force, t is the time variable, Not equal to zero and E(t) is proportional to Acos(t), A is the maximum stroke during the process of moving the mover from the forward maximum stroke position to the reverse maximum stroke position, and the moment when the mover is at the forward maximum stroke position≤t ≤The moment when the mover is at the reverse maximum travel position.

As a further improvement in an embodiment of the present invention, the generation of the eigenvalue of the back electromotive force includes: the maximum value of eigenvalue=|E(t)|, wherein E(t) is the back electromotive force, t is a time variable, And E(t) is proportional to Acos(t), A is the maximum stroke during the process of the mover moving from the forward maximum stroke position to the reverse maximum stroke position, and the moment when the mover is at the forward maximum stroke position≤t≤mover The moment when the sub is in the reverse maximum travel position.

As a further improvement of an embodiment of the present invention, the generation of the characteristic value of the counter electromotive force includes: Among them, E(t) is the counter electromotive force, t is the time variable, and E(t) is proportional to Acos(t), A is the maximum stroke during the movement of the mover from the forward maximum stroke position to the reverse maximum stroke position, B is the moment when the mover is at the forward maximum travel position.

As a further improvement of an embodiment of the present invention, the generation of the characteristic value of the counter electromotive force includes: Among them, E(t) is the counter electromotive force, t is the time variable, and E(t) is proportional to Acos(t), A is the maximum stroke during the movement of the mover from the forward maximum stroke position to the reverse maximum stroke position, C is the moment when the mover is at the reverse maximum travel position.

An embodiment of the present invention provides a stroke estimation device for a linear compressor, the linear compressor includes a linear motor, the linear motor includes a coil for driving the mover to perform linear motion, and includes the following modules: eigenvalue generation The module is used to obtain the back electromotive force of the coil during the process of the mover moving from the forward maximum stroke position to the reverse maximum stroke position, and generate the characteristic value of the back electromotive force; the processing module is used to determine the characteristic When the value is less than the preset value, the power of the linear motor is increased; otherwise, the power of the linear motor is decreased.

An embodiment of the present invention provides a linear compressor equipped with the above-mentioned stroke estimation device.

An embodiment of the present invention provides a refrigerator equipped with the above-mentioned linear compressor.

Compared with the prior art, the technical effect of the present invention is that the embodiment of the present invention provides a method for estimating the stroke of a linear compressor, the linear compressor includes a linear motor, and the linear motor includes a motor for driving the mover The linear motion coil comprises the following steps: during the process of moving the mover from the forward maximum stroke position to the reverse maximum stroke position, obtaining the back electromotive force of the coil, and generating the eigenvalue of the back electromotive force; determining the characteristic When the value is less than the preset value, the power of the linear motor is increased; otherwise, the power of the linear motor is decreased. Therefore, the stroke of the linear compressor can be precisely controlled.

Description of drawings

FIG. 1 is a schematic flow chart of a method for estimating a journey in an embodiment of the present invention;

Fig. 2 is a schematic structural diagram of a circuit for obtaining the back electromotive force of a linear motor in an embodiment of the present invention;

Fig. 3 is a schematic diagram of the principle of the stroke estimation method in the embodiment of the present invention;

Fig. 4 is the first graph of the back electromotive force of the linear motor in the embodiment of the present invention;

Fig. 5 is the second graph of the back electromotive force of the linear motor in the embodiment of the present invention;

FIG. 6 is a third graph of the back electromotive force of the linear motor in the embodiment of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with various embodiments shown in the drawings. However, these embodiments do not limit the present invention, and any structural, method, or functional changes made by those skilled in the art according to these embodiments are included in the protection scope of the present invention.

An embodiment of the present invention provides a stroke estimation method for a linear compressor, the linear compressor includes a linear motor, and the linear motor includes a coil for driving the mover 3 to perform linear motion, as shown in Figure 1, including The following steps:

Step 101: During the movement of the mover 3 from the forward maximum stroke position to the reverse maximum stroke position, obtain the back electromotive force of the coil, and generate the characteristic value of the back electromotive force; here, during the operation of the linear motor, The mover 3 will move back and forth in a straight line, that is, move back and forth between the first side and the second side; in a reciprocating back and forth movement, the mover 3 will first move from the first side to the second side, and then Then move back to the first side, and then do the next round of reciprocating back and forth, and cycle continuously; therefore, you can set the first side to the forward maximum stroke position and the second side to the reverse maximum stroke position position, or set the second side as the forward maximum travel position and the first side as the reverse maximum travel position. It can be understood that during the movement of the mover 3, a counter electromotive force will be generated in the coil. Here, the circuit diagram shown in Figure 2 can be used to obtain the counter electromotive force, that is, through the first motor power line 1 and the second motor power line Line 2 to get back EMF.

Step 102: When it is determined that the characteristic value is smaller than a preset value, increase the power of the linear motor, otherwise, decrease the power of the linear motor. Here, the power can be increased or decreased by changing the supply voltage etc. to the linear motor.

As shown in Figure 3, assuming that A1 is the forward maximum stroke position and A2 is the reverse maximum stroke position, when the mover 3 moves from A1 to A2, if the power of the linear motor is too large, the movement speed of the mover 3 It must be too fast, then it will inevitably cross A2 (that is, the stroke exceeds the limit value), and will eventually stop (for example, at the position A3 in Figure 3), then it is very likely that there will be an impact on the exhaust valve or an abnormal impact Noise and other issues; and because the frequency of the linear motor is usually fixed, therefore, because the moving speed of the mover 3 is too fast, at the same time, the counter electromotive force of the coil must also become larger (relative to the normal speed situation); Similar to this, if the moving speed of the mover 3 is too slow, then the mover 3 will definitely not reach A2 and will stop. Therefore, at the same time, the counter electromotive force of the coil must also become smaller (compared to the situation when the speed is normal) Said); so that the power of the linear motor can be judged according to the counter electromotive force of the coil.

Optionally, during the first reciprocating movement, during the movement of the mover 3 from the forward maximum stroke position to the reverse maximum stroke position (for ease of description, this movement is set as the first half), if it is judged If the power of the linear motor is too small, you can increase the power of the linear motor when the mover moves from the reverse maximum stroke position back to the forward maximum stroke position (for the convenience of description, this movement is set as the second half). , Conversely, reduce the power of the linear motor. Here, since the time interval between the first half and the second half is usually relatively short, if the power in the first half is too large, the possibility of excessive power in the second half will be relatively high, and the latter can be reduced. The power in the first half; on the contrary, if the power in the first half is too small, the power in the second half may be relatively large, so you can increase the power in the second half.

Optionally, during the first reciprocating movement, during the movement of the mover 3 from the forward maximum stroke position to the reverse maximum stroke position, if it is judged that the power of the linear motor is too small, then the second In the reciprocating motion, the power of the linear motor is increased, and vice versa, the power of the linear motor is decreased. Here, since the time interval between the first reciprocating movement and the second reciprocating movement is usually relatively short, the first power required for the first reciprocating movement and the second reciprocating movement required The difference between the second powers is usually relatively small. Therefore, if the second power is equal to the first power, it can effectively prevent the possibility that the stroke is not within a reasonable range during the second reciprocating movement.

In this stroke estimation method, when the mover 3 moves from the forward maximum stroke position to the reverse maximum stroke position, the electromotive force of the coil will be obtained to adjust the power. It can be seen that the control granularity is very fine (that is, in the mover 3, during each reciprocating movement, it will detect whether the stroke of the mover is suitable), and fine control can be carried out. Therefore, in the initial start-up stage of the refrigeration system, the whole system is extremely unstable and the working conditions continue to change. The stroke estimation method can reflect the maximum stroke position in each operation cycle in real time, and provide position feedback information in real time, so as to adjust the control amount in real time and achieve the purpose of stroke protection.

In a linear motor, the mover is usually a magnet, and the mathematical model of its motion can be understood as a simple harmonic motion, that is, the relationship between the stroke X and the time t is: X(t)=A*sin(ω*t), where X is the stroke of the mover 3 at time t, and A is the maximum stroke of the mover 3; since the frequency of the linear motor changes very little, that is, the periodicity is relatively stable, for the convenience of discussion, the value of ω will not be discussed temporarily; its waveform is shown in Figure 4 Show.

According to the mover motion stroke equation X(t), the mover speed V equation at time t can be obtained: (ignoring the value of ω), its waveform is shown by the dotted line in Figure 5; as shown in Figure 5, the phase difference between the stroke and the back EMF is 90°, that is, when the stroke is the largest, the back EMF is 0, and when the stroke is the smallest, the back EMF is the largest. When the mover is at the forward maximum travel position and the reverse maximum travel position, the velocity V=0, and then reverse movement. According to Faraday's law of electromagnetic induction, the counter electromotive force generated when the mover moves in the magnetic field is: E=B*L*V*sinθ, where B is the magnetic field strength, L is the length of the wire coil moving in the magnetic field, and V is the wire motion Velocity, θ is the angle between the magnetic field and the moving direction of the wire, and B*sinθ is understood as the component of the magnetic field perpendicular to the moving direction of the coil. To sum up, the equation of back electromotive force E at time t can be obtained as E(t)=B*sinθ*L*A*cos(t). For a fixed motor, both B*sinθ and L are set Quantity. It can be seen from the above formula that during the movement of the mover, the instantaneous value of the counter electromotive force is proportional to A*cos(t). It can be seen from the above formula that when the maximum stroke A of the cycle is different, the obtained counter electromotive force is different. For example, in Fig. 6, the solid line is the situation of A=5, the dotted line is the situation of A=7, and from the figure It can be seen that some eigenvalues of these two curves are different, therefore, it can be determined whether A meets the requirements (that is, whether the stroke of the linear compressor meets the requirements) based on the eigenvalues.

Optionally, when the mover 3 moves from the forward maximum stroke position to the reverse maximum stroke position, the linear compressor is in the suction and exhaust process, and the speed V(t) curve of the mover when the mover is running at high power compression on the exhaust side Slight distortion changes will affect the back electromotive force curve and jitter, so according to actual needs, the value of E(t) on the suction side is relatively stable.

Preferably, said generating the eigenvalue of said back electromotive force includes: Among them, E(t) is the counter electromotive force, t is the time variable, and E(t) is proportional to Acos(t), A is the maximum stroke during the movement of the mover from the forward maximum stroke position to the reverse maximum stroke position, The moment when the mover is at the maximum stroke position in the forward direction ≤ T ₁ ≤ _{T 2} ≤ The time when the mover is at the maximum stroke position in the reverse direction. Here, as shown in Figure 6, assuming that the A=5 solid line meets the requirements, the dotted line corresponding to A=7 is the situation of forming too large, then the eigenvalue corresponding to A=5 (ie ) is smaller than the eigenvalue corresponding to A=7 (ie ).

Preferably, said generation of the eigenvalue of the back electromotive force includes: eigenvalue=|E(t)|, wherein E(t) is the back electromotive force, t is a time variable, E(t) is not equal to zero and is proportional to Acos (t), A is the maximum stroke during the process of moving the mover from the forward maximum stroke position to the reverse maximum stroke position, the moment when the mover is at the forward maximum stroke position≤t≤the time when the mover is at the reverse maximum stroke position time.

Preferably, said generating the eigenvalue of said back electromotive force includes: Where E(t) is the back electromotive force, t is the time variable, Not equal to zero and E(t) is proportional to Acos(t), A is the maximum stroke during the process of moving the mover from the forward maximum stroke position to the reverse maximum stroke position, and the moment when the mover is at the forward maximum stroke position≤t ≤The moment when the mover is at the reverse maximum travel position.

Preferably, said generation of the eigenvalue of the back electromotive force includes: the maximum value of eigenvalue=|E(t)|, wherein E(t) is the back electromotive force, t is a time variable, and E(t) is proportional to Acos(t), A is the maximum stroke during the process of the mover moving from the forward maximum stroke position to the reverse maximum stroke position, the moment when the mover is at the forward maximum stroke position≤t≤the mover is at the reverse maximum stroke position moment.

Preferably, said generating the eigenvalue of said back electromotive force includes: Among them, E(t) is the counter electromotive force, t is the time variable, and E(t) is proportional to Acos(t), A is the maximum stroke during the movement of the mover from the forward maximum stroke position to the reverse maximum stroke position, B is the moment when the mover is at the forward maximum travel position.

Preferably, said generating the eigenvalue of said back electromotive force includes: Among them, E(t) is the counter electromotive force, t is the time variable, and E(t) is proportional to Acos(t), A is the maximum stroke during the movement of the mover from the forward maximum stroke position to the reverse maximum stroke position, C is the moment when the mover is at the reverse maximum travel position.

The embodiment of the present invention also provides a stroke estimation device for a linear compressor, the linear compressor includes a linear motor, and the linear motor includes a coil for driving the mover to perform linear motion, including the following modules:

An eigenvalue generation module, used to obtain the back electromotive force of the coil during the movement of the mover from the forward maximum stroke position to the reverse maximum stroke position, and generate the eigenvalue of the back electromotive force;

A processing module, configured to increase the power of the linear motor when it is determined that the characteristic value is smaller than a preset value, otherwise, decrease the power of the linear motor.

An embodiment of the present invention provides a linear compressor equipped with the above-mentioned stroke estimation device.

An embodiment of the present invention provides a refrigerator installed with the above-mentioned linear compressor.

It should be understood that although this description is described according to implementation modes, not each implementation mode only contains an independent technical solution, and this description in the description is only for clarity, and those skilled in the art should take the description as a whole, and each The technical solutions in the embodiments can also be properly combined to form other embodiments that can be understood by those skilled in the art.

The series of detailed descriptions listed above are only specific descriptions for feasible implementations of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent implementation or implementation that does not depart from the technical spirit of the present invention All changes should be included within the protection scope of the present invention.

Claims (10)

1. A stroke estimation method for a linear compressor, the linear compressor includes a linear motor, and the linear motor includes a coil for driving the mover to do linear motion, it is characterized in that, comprising the following steps: During the process of the mover moving from the forward maximum stroke position to the reverse maximum stroke position, the back electromotive force of the coil is obtained, and the characteristic value of the back electromotive force is generated; When it is determined that the characteristic value is smaller than a preset value, the power of the linear motor is increased; otherwise, the power of the linear motor is decreased. 2. The stroke estimation method according to claim 1, wherein said generating the eigenvalue of said counter electromotive force comprises: Among them, E(t) is the counter electromotive force, t is the time variable, and E(t) is proportional to Acos(t), A is the maximum stroke during the movement of the mover from the forward maximum stroke position to the reverse maximum stroke position, The moment when the mover is at the maximum stroke position in the forward direction ≤ T ₁ ≤ _{T 2} ≤ The time when the mover is at the maximum stroke position in the reverse direction. 3. The stroke estimation method according to claim 1, wherein said generating the eigenvalue of said counter electromotive force comprises: Eigenvalue=|E(t)|, where E(t) is the counter electromotive force, t is the time variable, E(t) is not equal to zero and is proportional to Acos(t), A is the mover moving from the forward maximum stroke position to The maximum stroke during the reverse maximum stroke position, the moment when the mover is at the forward maximum stroke position≤t≤the time when the mover is at the reverse maximum stroke position. 4. The stroke estimation method according to claim 1, wherein said generating the eigenvalue of said counter electromotive force comprises: Where E(t) is the back electromotive force, t is the time variable, Not equal to zero and E(t) is proportional to Acos(t), A is the maximum stroke during the process of moving the mover from the forward maximum stroke position to the reverse maximum stroke position, and the moment when the mover is at the forward maximum stroke position≤t ≤The moment when the mover is at the reverse maximum travel position. 5. The stroke estimation method according to claim 1, wherein said generating the eigenvalue of said counter electromotive force comprises: Eigenvalue = the maximum value of |E(t)|, where E(t) is the counter electromotive force, t is the time variable, and E(t) is proportional to Acos(t), A is the movement of the mover from the positive to the maximum stroke position The maximum stroke during the process to the reverse maximum stroke position, the moment when the mover is at the forward maximum stroke position ≤ t ≤ the time when the mover is at the reverse maximum stroke position. 6. The stroke estimation method according to claim 1, wherein said generating the eigenvalue of said counter electromotive force comprises: Among them, E(t) is the counter electromotive force, t is the time variable, and E(t) is proportional to Acos(t), A is the maximum stroke during the movement of the mover from the forward maximum stroke position to the reverse maximum stroke position, B is the moment when the mover is at the forward maximum travel position. 7. The stroke estimation method according to claim 1, wherein said generating the eigenvalue of said counter electromotive force comprises: Among them, E(t) is the counter electromotive force, t is the time variable, and E(t) is proportional to Acos(t), A is the maximum stroke during the movement of the mover from the forward maximum stroke position to the reverse maximum stroke position, C is the moment when the mover is at the reverse maximum travel position. 8. A stroke estimation device for a linear compressor, the linear compressor includes a linear motor, and the linear motor includes a coil for driving the mover to perform linear motion, characterized in that it includes the following modules: An eigenvalue generation module, used to obtain the back electromotive force of the coil during the movement of the mover from the forward maximum stroke position to the reverse maximum stroke position, and generate the eigenvalue of the back electromotive force; A processing module, configured to increase the power of the linear motor when it is determined that the characteristic value is smaller than a preset value, otherwise, decrease the power of the linear motor. 9. A linear compressor, characterized in that the stroke estimating device according to claim 8 is installed. 10. A refrigerator, characterized in that the linear compressor according to claim 9 is installed.