JP3768064B2 - Linear compressor drive unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a linear compressor drive device, and more particularly to a linear compressor drive device that generates a compressed gas by reciprocating a piston by a linear motor.
[0002]
[Prior art]
Development of applying a linear compressor as a drive mechanism for compressing expanded refrigerant gas in a cooling device such as a refrigerator is underway.
[0003]
FIG. 1 is a cross-sectional view showing a configuration of a known linear compressor (10). The linear compressor (10) is formed at one end of the cylinder (11) by inserting the piston (12) into the cylinder (11) so as to be reciprocally movable and reciprocating the piston (12) by the linear motor (40). The gas in the compressed compression chamber (13) is compressed.
[0004]
The linear motor (40) includes a stator (22) formed by winding electromagnetic coils (30) (30) around double cylindrical yoke portions (15) (15a) formed on the casing (14). And a movable body (20) having a cylindrical permanent magnet (32) formed at one end of the piston (12). The permanent magnet (32) is inserted between the yoke portions (15) and (15a) so as to be reciprocally movable. The movable body (20) is connected to the stator (22) via a piston spring (16), and the movable body (20) is further soundproofed and protected against the casing (14). A mounting spring (17) for vibration is attached.
The linear motor (40) can also be configured by winding the electromagnetic coil (30) around the movable body (20) and providing the permanent magnet (32) on the stator (22).
[0005]
When an AC voltage V is applied to the electromagnetic coil (30) and an electric current I flows, an electromagnetic force in a direction corresponding to the direction of the electric current I acts on the permanent magnet (32) that is the movable body (20), The piston (12) reciprocates in the cylinder (11).
In order to increase the energy efficiency (ratio of output energy to input energy) of the linear compressor (10), it is desirable to vibrate the movable body (20) in the vicinity of the resonance frequency.
The resonance frequency Fc of the linear compressor (10) is the weight of the movable body (20) including the piston (12), the so-called spring constant of the gas spring that occurs with the pressure fluctuation of the gas in the compression chamber (13), and the piston spring (16 ) Spring constant.
[0006]
Since the linear compressor (10) is generally driven by commercial power, the resonance frequency Fc of the linear compressor (10) is set to coincide with the frequency (50/60 Hz) of the AC voltage V of commercial power.
[0007]
When the spring constant of the gas spring changes due to a change in the load immediately after the start of operation or during steady operation, the vibration of the movable body (20) becomes a vibration with a frequency shifted from the resonance frequency Fc, which is the frequency of the power supply voltage V. There is a problem that the energy efficiency is lowered.
[0008]
When the inductance L due to the electromagnetic coil (30) is small, the AC voltage V of the power supply is shown in FIG. 7 (a), where the vertical axis is the real axis and the horizontal axis is the imaginary axis. Can be expressed as a combined vector of the back electromotive force E generated in step S3, the current I of the linear motor 40 and the voltage drop RI generated by the winding resistance R. The counter electromotive force E is an electromotive force proportional to the relative moving speed generated in the electromagnetic coil (30) when the electromagnetic coil (30) moves relative to the permanent magnet (32). .
Therefore, the applicant detects the phase difference θ ′ between the power supply voltage V supplied to the linear motor (40) and the current I of the linear motor (40) in Japanese Patent Application Laid-Open No. 9-112438, and FIG. As shown in FIG. 7 (b), the frequency of the AC power supply is adjusted so that the phase difference θ ′ = 0, and the resonance frequency Fc that fluctuates with the load fluctuation is made to coincide with the frequency F of the AC power supply. In addition, a linear motor drive device that performs energy-efficient operation has been proposed.
[0009]
[Problems to be solved by the invention]
When the inductance L of the electromagnetic coil (30) is small, as described above, the frequency F of the AC power supply is adjusted so that the phase difference θ ′ between the power supply voltage V and the current I flowing through the linear motor (40) is zero. Then, the linear motor (40) can be operated in a resonance state.
However, when the inductance L of the electromagnetic coil (30) is large, as shown in FIG. 3 (a), the voltage ωLI generated by the inductance L cannot be ignored. Therefore, the phase of the power supply frequency F is simply shifted by the phase difference θ. The resonance state could not be restored.
[0010]
An object of the present invention is to provide a drive device for a linear compressor that can be operated in a resonance state and maintain high energy efficiency even when the inductance L of the electromagnetic coil is large.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the drive device (60) of the linear compressor (10) according to claim 1 of the present invention is provided with a permanent magnet (32) on one of the movable body (20) and the stator (22). A driving device for a linear compressor comprising a linear motor (40) provided with an electromagnetic coil (30) on the other side,
An AC power source (50) capable of controlling the frequency of the drive voltage V applied to the electromagnetic coil (30);
Voltage detection means (52) for detecting the drive voltage V of the AC power supply (50);
Current detection means (53) for detecting the current I flowing in the electromagnetic coil (30);
A phase detection means (55) for detecting a phase difference θ between the drive voltage V detected by the voltage detection means (52) and the current I detected by the current detection means (53);
An imaginary axis component Vi of the driving voltage V is calculated from the phase difference θ detected by the phase detecting means (55) and the driving voltage V detected by the voltage detecting means (52), and the calculated imaginary axis component Vi and By calculating the frequency correction amount ΔF corresponding to the difference between the voltage ωLI generated in the electromagnetic coil (30) and correcting the frequency of the drive voltage V of the AC power source (50) by a value corresponding to the frequency correction amount ΔF. And a correcting means (57) for matching the frequency of the drive voltage V with the resonance frequency of the movable body (20).
[0012]
According to a second aspect of the present invention, in the driving device (60) of the linear compressor (10), a permanent magnet (32) is provided on one of the movable body (20) and the stator (22), and an electromagnetic coil ( 30) a linear compressor drive comprising a linear motor (40),
An AC power source (50) capable of controlling the frequency of the drive voltage V applied to the electromagnetic coil (30);
Voltage detection means (52) for detecting the drive voltage V of the AC power supply (50);
Current detection means (53) for detecting the current I flowing in the electromagnetic coil (30);
A phase detection means (55) for detecting a phase difference θ between the drive voltage V detected by the voltage detection means (52) and the current I detected by the current detection means (53);
An imaginary axis component Vi of the driving voltage V is calculated from the phase difference θ detected by the phase detecting means (55) and the driving voltage V detected by the voltage detecting means (52), and the calculated imaginary axis component Vi and The imaginary axis component Ei of the counter electromotive voltage E generated in the electromagnetic coil (30) is calculated from the difference from the voltage ωLI generated in the electromagnetic coil (30), and based on the counter electromotive voltage E and the imaginary axis component Ei of the counter electromotive voltage E. The phase difference ψ between the back electromotive force E and the current I is calculated, the frequency correction amount ΔF corresponding to the calculated phase difference ψ is calculated, and only the value corresponding to the frequency correction amount ΔF is AC power source (50). Correction means (57) for making the frequency of the drive voltage V coincide with the resonance frequency of the movable body (20) by correcting the frequency of the drive voltage V.
[0013]
[Action and effect]
According to the linear compressor drive device of the first aspect of the present invention, the calculation is based on the phase difference θ between the drive voltage V supplied to the electromagnetic coil (30) and the current I flowing through the electromagnetic coil (30). The frequency correction amount ΔF is calculated according to the difference between the imaginary axis component Vi of the generated drive voltage V and the voltage ωLI generated in the electromagnetic coil, the frequency of the drive voltage V is corrected based on the calculated value ΔF, and the drive The frequency of the voltage V can be matched with the resonance frequency of the movable body (20).
Since the frequency of the drive voltage V is controlled in consideration of the inductance of the electromagnetic coil (30), the energy efficiency does not decrease due to the initial operation state or load fluctuations, and the low power factor linear motor However, highly efficient resonant operation is possible.
[0014]
According to the linear compressor drive device of the present invention, the calculation is based on the phase difference θ between the drive voltage V supplied to the electromagnetic coil (30) and the current I flowing through the electromagnetic coil (30). The imaginary axis component Ei of the counter electromotive voltage E generated in the electromagnetic coil (30) is calculated according to the difference between the imaginary axis component Vi of the generated drive voltage V and the voltage ωLI generated in the electromagnetic coil. A phase difference ψ between the back electromotive voltage E and the current I is calculated. A frequency correction amount ΔF corresponding to the calculated phase difference ψ is calculated, the frequency of the drive voltage V is corrected based on the calculated value ΔF, and the frequency of the drive voltage V is matched with the resonance frequency of the movable body (20). be able to.
Also in claim 2, since the frequency control of the drive voltage V is performed in consideration of the inductance of the electromagnetic coil (30), the energy efficiency is not lowered even by the initial operation state or load fluctuations. Resonant operation with high efficiency is possible even with a low power factor linear motor.
[0015]
According to the linear compressor driving apparatus of the present invention, the driving voltage V of the AC power source (50) is corrected in consideration of the inductance L of the electromagnetic coil (30), and the stroke of the movable body (20) is kept constant. Therefore, a large amount of power is supplied when the load is high, and a small amount of power is supplied when the load is low, and an appropriate cooling characteristic can be obtained for a refrigerator using this.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The linear motor (40) mounted on the linear compressor is formed by connecting an AC power supply (50) and an electromagnetic coil (30). When this is shown by an equivalent circuit, as shown in FIG. 2, the AC power source (50), the inductance L of the electromagnetic coil (30), the winding resistance R of the electromagnetic coil (30), and the reverse generated in the electromagnetic coil (30) It can be represented by an electromotive voltage E.
The counter electromotive voltage E generated in the electromagnetic coil (30) is a voltage generated in proportion to the relative moving speed between the electromagnetic coil (30) and the permanent magnet (32).
If the drive voltage of the AC power source (50) is V, and the current flowing through the equivalent circuit is I, the voltage drop of the inductance L is represented by ωLI, and the voltage drop due to the winding resistance is represented by RI.
[0017]
As shown in FIG. 3A, the drive voltage V has a voltage drop ωLI due to inductance L, a voltage drop RI due to winding resistance, and a back electromotive force E when the vertical axis is a real axis and the horizontal axis is an imaginary axis. And a composite vector.
[0018]
By the way, when the frequency of the current I does not match the resonance frequency Fc of the linear motor (40), referring to FIG. 3 (a), the back electromotive force E is advanced in phase by ψ with respect to the current I. (It may be a phase lag). In this case, a phase difference ψ is generated between the back electromotive voltage E and the current I, and these are not synchronized, so the linear motor (40) cannot be driven in a resonance state.
Therefore, by setting the phase difference ψ between the counter electromotive voltage E and the current I to zero as shown in FIG. 3 (b), the relative electromagnetic coil (30) in proportion to the counter electromotive voltage E is relative. The linear motor (40) is driven in a resonance state by synchronizing the moving speed with the current I.
[0019]
As described above, FIG. 4 shows the configuration of a specific driving device for operating the linear motor (40) in the resonance state, and FIG. 5 shows the flow of the control.
As shown in FIG. 4, the drive device (60) includes an AC power source (50), an electromagnetic coil (30) serving as a power source for the linear compressor (10), a voltage detection means (52), a current detection means (53), and A computer (58) is provided, and the computer (58) includes a phase detection means (55) and a correction means (57) for performing calculation and control.
[0020]
The AC power supply (50) applies a drive voltage V having a frequency f corresponding to the frequency control signal from the correction means (57) of the computer (58) to the electromagnetic coil (30). The voltage detection means (52) detects the voltage V applied to the electromagnetic coil (30) from the AC power supply (50), converts the detected value into a digital signal, and outputs the phase detection means (55) of the computer (58). (Step 1). The current detection means (53) detects the current I flowing from the AC power supply (50) to the electromagnetic coil (30), converts the detected value into a digital signal, and detects the phase detection means (55) of the computer (58). (Step 1).
[0021]
The phase detection means (55) of the computer (58) calculates the rise timing of the waveforms of the voltage V and current I based on the digital signals transmitted from the voltage detection means (52) and the current detection means (53). (Step 2) The phase difference θ of the current I with respect to the drive voltage V is calculated (Step 3 and FIG. 3 (a)). From the magnitude of the drive voltage V and the phase difference θ, the imaginary axis component Vi of the drive voltage V can be calculated (step 4). The imaginary axis component Vi represents the sum of the voltage drop ωLI due to the inductance L and the imaginary axis component Ei (= Esinψ) of the back electromotive voltage E, as shown in FIG. Since the voltage drop ωLI due to the inductance L can be calculated based on the current I measured by the current detection means (53), the difference between the imaginary axis component Vi of the drive voltage V and the voltage drop ωLI due to the inductance L (= Vi−ωLI). ), The imaginary axis component Esinψ of the back electromotive force E is calculated.
In the correcting means (57), the relationship between the imaginary axis component Esinψ of the back electromotive force E and the frequency correction amount ΔF necessary for setting the phase difference ψ to zero is stored as a calculation formula or a data table. The correction means (57) calculates the frequency correction amount ΔF corresponding to the phase difference ψ detected by the phase detection means (55) (step 5), and the frequency control amount F (= F + ΔF) based on the calculation result is calculated as the frequency. The control signal is transmitted to the AC power source (50) (step 7).
When the AC power source (50) corrects the drive voltage V according to the received frequency control amount F, the phase difference between the back electromotive force E and the current I becomes zero as shown in FIG. The relative movement speed of 30) coincides with the current I, the linear motor (40) resonates, and the control ends (step 8).
[0022]
The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. Moreover, each part structure of this invention is not restricted to the said Example, A various deformation | transformation is possible within the technical scope as described in a claim.
[0023]
For example, in step 5, the frequency correction amount ΔF is calculated from the imaginary axis component Esinψ of the drive voltage V in the above, but as shown in FIG. The phase difference ψ with the voltage E may be calculated, and the frequency correction amount ΔF corresponding to the calculated value may be derived (step 9 to step 11). In this case, the correction means (57) of the computer (58) indicates the relationship between the phase difference ψ between the back electromotive force E and the current I and the frequency correction amount ΔF necessary for making the phase difference ψ zero. It may be stored as a calculation formula or a data table.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a linear compressor.
FIG. 2 is an equivalent circuit of a linear motor.
FIG. 3A is a vector diagram showing the relationship between voltage and current when the current and speed are not synchronized; FIG. 3B is a diagram showing the relationship between the voltage and current in the resonance state when the current and speed are synchronized; It is a vector diagram which shows the relationship.
FIG. 4 is a block diagram showing a driving apparatus for a linear compressor according to the present invention.
FIG. 5 is a flowchart showing a control flow of the present invention.
FIG. 6 is a flowchart showing a different embodiment of the present invention.
7A and 7B are vector diagrams showing a conventional control method, in which FIG. 7A shows a state in which current and voltage are not synchronized, and FIG. 7B shows a state in which current and voltage are synchronized.
[Explanation of symbols]
(10) Linear compressor
(30) Electromagnetic coil
(40) Linear motor
(50) AC power supply
(52) Voltage detection means
(53) Current detection means
(55) Phase detection means
(57) Correction means

Claims (2)

A linear compressor driving device comprising a linear motor (40) in which a permanent magnet (32) is provided on one of a movable body (20) or a stator (22) and an electromagnetic coil (30) is provided on the other. ,
An AC power source (50) capable of controlling the frequency of the drive voltage V applied to the electromagnetic coil (30);
Voltage detection means (52) for detecting the drive voltage V of the AC power supply (50);
Current detection means (53) for detecting the current I flowing in the electromagnetic coil (30);
A phase detection means (55) for detecting a phase difference θ between the drive voltage V detected by the voltage detection means (52) and the current I detected by the current detection means (53);
An imaginary axis component Vi of the driving voltage V is calculated from the phase difference θ detected by the phase detecting means (55) and the driving voltage V detected by the voltage detecting means (52), and the calculated imaginary axis component Vi and By calculating the frequency correction amount ΔF corresponding to the difference between the voltage ωLI generated in the electromagnetic coil (30) and correcting the frequency of the drive voltage V of the AC power source (50) by a value corresponding to the frequency correction amount ΔF. Correction means (57) for matching the frequency of the drive voltage V with the resonance frequency of the movable body (20);
A linear compressor driving device characterized by comprising: A linear compressor driving device comprising a linear motor (40) in which a permanent magnet (32) is provided on one of a movable body (20) or a stator (22) and an electromagnetic coil (30) is provided on the other. ,
An AC power source (50) capable of controlling the frequency of the drive voltage V applied to the electromagnetic coil (30);
Voltage detection means (52) for detecting the drive voltage V of the AC power supply (50);
Current detection means (53) for detecting the current I flowing in the electromagnetic coil (30);
A phase detection means (55) for detecting a phase difference θ between the drive voltage V detected by the voltage detection means (52) and the current I detected by the current detection means (53);
An imaginary axis component Vi of the driving voltage V is calculated from the phase difference θ detected by the phase detecting means (55) and the driving voltage V detected by the voltage detecting means (52), and the calculated imaginary axis component Vi and The imaginary axis component Ei of the counter electromotive voltage E generated in the electromagnetic coil (30) is calculated from the difference from the voltage ωLI generated in the electromagnetic coil (30), and based on the counter electromotive voltage E and the imaginary axis component Ei of the counter electromotive voltage E. The phase difference ψ between the back electromotive force E and the current I is calculated, the frequency correction amount ΔF corresponding to the calculated phase difference ψ is calculated, and only the value corresponding to the frequency correction amount ΔF is AC power source (50). Correction means (57) for making the frequency of the drive voltage V coincide with the resonance frequency of the movable body (20) by correcting the frequency of the drive voltage V of
A linear compressor driving device characterized by comprising:

Images