JP3869632B2 - Linear compressor drive controller - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drive control device for a linear compressor, and more particularly to a drive control device for a linear compressor that generates a compressed gas by reciprocating a piston in a cylinder by a linear motor.
[0002]
[Prior art]
In recent years, a linear compressor has been developed as a mechanism for compressing refrigerant gas expanded in a cooling device such as a refrigerator. In this linear compressor, gas is compressed by reciprocating a piston in a cylinder by a linear motor.
[0003]
In such a linear compressor, high efficiency can be obtained when the phase of the drive current of the linear motor and the speed of the piston coincide. That is, high efficiency is obtained when the frequency of the drive current matches the resonance frequency determined from the hardware configuration of the linear compressor, the gas spring constant, and the like. Further, the highest efficiency can be obtained when the closest distance between the piston head and the end of the inner wall of the cylinder is maintained at a minimum value.
[0004]
On the other hand, since the resonance frequency of the linear compressor varies depending on the load condition, in order to continue the operation with high efficiency, the drive frequency is changed so that the drive frequency falls within an allowable range near the resonance frequency.
[0005]
When the drive frequency approaches the resonance frequency, the electric power necessary for driving the piston decreases, so that an excessively large drive current is temporarily supplied to the linear motor. For this reason, there exists a possibility that the amplitude of a piston may exceed the target amplitude and may collide with the upper wall of a cylinder.
[0006]
In order to avoid such an overstroke of the piston, for example, in a linear compressor driving apparatus described in Japanese Patent Laid-Open No. 10-115290, a current gain when calculating a current command value serving as a reference for driving current is set. It was reduced by several percent in advance.
[0007]
[Problems to be solved by the invention]
However, the linear compressor driving apparatus described above has the following problems.
[0008]
In a conventional linear compressor drive device, after changing the drive frequency, it is confirmed whether the drive frequency is within an allowable range near the resonance frequency. When the drive frequency is not within the allowable range, the change of the drive frequency and the confirmation thereof are repeated until the drive frequency falls within the allowable range.
[0009]
As described above, when changing the drive frequency, the current gain is reduced by several percent in order to avoid the overstroke of the piston. For this reason, if the drive frequency is continuously changed, the amplitude (stroke) of the piston may become smaller than necessary. As a result, there has been a problem that the flow rate of the discharge gas discharged from the cylinder is reduced and the efficiency of the compressor is lowered.
[0010]
The present invention has been made to solve the above problems, and provides a drive control device for a linear compressor that can prevent the piston stroke from becoming unnecessarily small when changing the drive frequency. Objective.
[0011]
[Means for Solving the Problems]
The linear compressor drive control device according to the present invention includes current command means, position detection means, amplitude detection means, frequency control means, and amplitude control means. The current command means generates a current command value in accordance with a position function that serves as a reference for the position of the piston, and generates a drive current corresponding to the current command value. The position detection means detects the position of the piston in the cylinder. The amplitude detection means detects the amplitude of the piston in the cylinder. The frequency control means adjusts the drive frequency to a target resonance frequency. The amplitude control means matches the piston amplitude with a predetermined target amplitude based on the piston amplitude detected by the amplitude detection means. In the frequency control means, when the drive frequency is not within the allowable range of the target resonance frequency, processing for adjusting the drive frequency to the target resonance frequency is performed, and when the drive frequency is within the allowable range. The process of adjusting the drive frequency to the target resonance frequency is not performed. Further, in the amplitude control means, when the frequency control means matches the drive frequency to the target resonance frequency, the piston amplitude detected by the amplitude detection means exceeds a predetermined reference amplitude smaller than the target amplitude. Amplitude reduction processing for reducing the amplitude of the piston is performed, and when the piston amplitude does not exceed the predetermined reference amplitude, the amplitude reduction processing is not performed.
[0012]
According to this configuration, when the drive frequency is adjusted to the target resonance frequency in the frequency control means, the piston amplitude exceeds a predetermined reference amplitude smaller than the target amplitude. Ru In this case, amplitude reduction processing for reducing the piston amplitude is performed, and when the piston amplitude does not exceed a predetermined reference amplitude, the amplitude reduction processing is not performed. And the drive frequency is resonant frequency number If the value falls within the allowable value range, the drive frequency changing process is not performed, and the piston amplitude is adjusted to the target amplitude. Thus, even when the process of bringing the drive frequency close to the resonance frequency is repeated, the piston amplitude (stroke) does not become unnecessarily small. As a result, it is possible to prevent the efficiency of the linear compressor from being lowered due to a decrease in gas discharge amount.
[0013]
Such an amplitude reduction process preferably includes a process for reducing the current command value generated by the current command means to a predetermined ratio. Moreover, it is preferable that the process which reduces the amplitude of a position function to a predetermined ratio is included.
[0014]
Preferably, speed detection means for detecting the speed of the piston in the cylinder, and phase difference detection means for detecting a phase difference between the current command value generated by the current command means and the speed detected by the speed detection means, And the frequency control means controls the frequency of the position function so that the phase difference detected by the phase difference detection means is eliminated.
[0015]
Thereby, the drive frequency is controlled so as to approach the resonance frequency.
Preferably, in the amplitude detection means, the top dead center side amplitude corresponding to the length between the top dead center and the origin of the piston, the bottom dead center and the origin of the piston based on the detection result of the position detection means. The bottom dead center side amplitude corresponding to the length between the top dead center side amplitude and the bottom dead center side amplitude detected in advance by the amplitude control means is previously determined by the amplitude control means. It is controlled so as to coincide with a predetermined target amplitude.
[0016]
Thereby, even if the neutral point of the piston deviates from the origin, the piston can be prevented from colliding with the upper wall surface of the cylinder. Here, the origin is a point defined as the center of vibration of the position function.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
A linear compressor drive control apparatus according to an embodiment of the present invention will be described. First, FIG. 3 shows an example of the structure of a linear compressor. As shown in FIG. 3, the linear compressor 1 includes a pair of cylinders 11 a and 11 b provided at an upper end portion and a lower end portion of a cylindrical casing 10, and 1 inserted into the cylinders 11 a and 11 b, respectively. A pair of pistons 12a and 12b is provided.
[0018]
A pair of compression chambers 13a and 13b are formed between the heads of the pistons 12a and 12b and the upper walls of the cylinders 11a and 11b, respectively. Suction valves 14a and 14b and discharge valves 15a and 15b that open and close according to the gas pressure in the compression chambers 13a and 13b are attached to the cylinders 11a and 11b, respectively.
[0019]
The pair of pistons 12a and 12b are connected to one end and the other end of one rod 16, respectively. The rod 16 is supported by a pair of bearings 17a, 17b and coil springs 18a, 18b so as to reciprocate within the casing 10 and the cylinders 11a, 11b.
[0020]
The linear compressor 1 also includes a linear motor 20 for reciprocally driving the pistons 12a and 12b. The linear motor 20 is a voice coil motor, and includes a fixed portion including a yoke portion 10a and a permanent magnet 21, and a movable portion including a coil 23 and a cylindrical support member 24. The yoke portion 10 a constitutes a part of the casing 10. The permanent magnet 21 is fixed to the inner peripheral wall of the yoke portion 10a.
[0021]
One end of the support member 24 is loosely inserted into a cylindrical space between the permanent magnet 21 and the outer wall of the main body barrel 12, and the other end is connected to the center of the rod 16. The coil 23 is attached to one end of the support member 24 and faces the permanent magnet 21.
[0022]
A magnet plate 42 in which N poles and S poles are alternately magnetized at a constant pitch is fixed to an arm 160 protruding from the center of the rod 16. An MR element 41 is attached to the protrusion 100 formed on the inner surface of the casing 10 so as to face the magnet plate 42. The MR element 41 and the magnet plate 42 constitute the displacement sensor 4. The displacement sensor 4 has outputs of the A phase and the B phase corresponding to the displacement, and an output to the Z phase when the rod 16 is at the origin position of the pair of pistons 12a and 12b.
[0023]
The linear compressor 1 described above has a resonance frequency determined by the masses of the pistons 12a and 12b, the rod 16, the coil 23 and the support member 24, the gas spring constant of the compression chambers 13a and 13b, the spring constant of the coil spring 18, and the like. Yes. This resonance frequency is usually set near the frequency of commercial power (for example, 60 Hz). By driving the linear motor 20 at this resonance frequency, the gas can be alternately compressed in the pair of upper and lower compression chambers 13a and 13b with high efficiency.
[0024]
Next, a drive device as a drive control device for the linear compressor will be described. FIG. 1 is a block diagram showing the configuration of the driving device 2. As shown in FIG. 1, the driving device 2 of the linear compressor 1 includes a motor driver 3, a control circuit 5, and a sensor signal processing circuit 6. The motor driver 3 supplies a drive current I to the linear motor of the linear compressor 1. The control circuit 5 is constituted by a microcomputer composed of a CPU, a memory, etc., and the control cycle by the CPU is, for example, 150 μsec.
[0025]
A sensor signal S output from a displacement sensor 4 provided in the linear compressor 1 is supplied to a sensor signal processing circuit 6 and converted into a square wave. The number of the square waves is counted, and position data Pa representing the displacement of the piston is created based on the count value and supplied to the control circuit 5.
[0026]
The control circuit 5 creates a control signal φc according to the position data Pa from the sensor signal processing circuit 6 and outputs the control signal φc to the motor driver 3 to control the output current I.
[0027]
FIG. 2 is a block diagram showing the configuration of the control circuit 5 shown in FIG. As shown in FIG. 2, the control circuit 5 includes a position command value generator 30, a position / speed controller 31, As current command means Current command value generator 32, As a position detection means Position / velocity detector 33, As an amplitude detection means Vertical dead center detector 34, current / velocity phase difference detector 35, As an amplitude control means Current gain control unit 36 and amplitude neutral position control unit 37 As frequency control means The frequency control unit 38 is configured.
[0028]
The position / velocity detection unit 33 takes in the position data Pa from the sensor signal processing circuit 6 and sets it as the current position value Pnow, and differentiates the current position value Pnow to obtain the current speed value Vnow.
[0029]
The top and bottom dead center detection unit 34 is based on a series of current position values Pnow obtained from the position / velocity detection unit 33, and corresponds to the length between the top dead center and the origin of the pistons 12a and 12b. The bottom dead center side amplitude corresponding to the amplitude and the length between the bottom dead center and the origin is detected. The detection of the top dead center side amplitude and the bottom dead center side amplitude is performed every time one cycle of the position command Pref is completed. That is, it is performed every time the position command Pref passes through the zero cross point (− → +).
[0030]
The current / velocity phase difference detection unit 35 is generated by the position / velocity detection unit 33. speed A phase difference between the current value Vnow and the current command value Iref generated by the current command value generation unit 32 is detected. This phase difference is a value corresponding to the difference between the current drive frequency and the resonance frequency. This phase difference is detected every time one cycle of the current position value Pnow is completed. That is, it is performed every time the current position value Pnow passes the zero cross point (− → +).
[0031]
The frequency control unit 38 determines whether or not the phase difference detected by the current / velocity phase difference detection unit 35 exceeds a predetermined allowable value, and if so, controls to eliminate the phase difference. That is, the angular frequency ω used in the position command value generation unit 30 is corrected so as to obtain the resonance frequency, and the corrected angular frequency ω is supplied to the position command value generation unit 30 as the target drive frequency.
[0032]
The amplitude neutral position control unit 37 compares the top dead center side amplitude and the bottom dead center side amplitude detected by the top and bottom dead center detection unit 34, and the position command value generation unit 30 reduces the difference between the two amplitudes. The shift amount B used is controlled every time one cycle of the position command value Pref is completed. That is, the amplitude neutral position control unit 37 corrects the shift amount B to the negative side (downward) when the top dead center side amplitude is larger than the bottom dead center side amplitude. On the other hand, when the top dead center side amplitude is smaller than the bottom dead center side amplitude, the shift amount B is corrected to the positive side (upward).
[0033]
Normally, the shift amount B is substantially constant due to the characteristics of the apparatus such as the asymmetry of the valve, so the work amount per shift amount B is set to a small value (for example, 1 μm). By controlling the shift amount B in this way, the top clearances of the pair of pistons 12a and 12b can be accurately controlled to the same value.
[0034]
The position command value generation unit 30 generates a position command value Pref based on the sine table stored in the memory, the amplitude A, the angular frequency ω, the shift amount B, and the expression Pref = Asinωt + B (sine function). The generated position command value Pref is given to the position / speed control unit 31.
[0035]
When generating the position command value Pref, the position command value generation unit 30 discretely extracts data sequentially from the sine table as a position function at a constant cycle (for example, 450 μsec). The drive frequency is determined by the data extraction interval at this time.
[0036]
The position / speed control unit 31 calculates the speed command value Vref based on the position command value Pref generated by the position command value generation unit 30, the current position value Pnow generated by the position / speed detection unit 33, and the deviation Pref-Pnow. Generate. Furthermore, a speed control value Vc is generated based on a deviation Vref−Vnow between the speed command value Vref and the current speed value Vnow generated by the position / speed detector 33.
[0037]
The current gain control unit 36 compares the top dead center side amplitude and the bottom dead center side amplitude detected by the top and bottom dead center detection unit 34, and is larger of the top dead center side amplitude and the bottom dead center side amplitude. Is the maximum amplitude current value Anow, and the value of the current gain Gi used in the current command value generation unit 32 is set so that the maximum amplitude current value Anow matches the predetermined maximum amplitude target value Aref. Control every cycle of vibration.
[0038]
Further, the current gain control unit 36 has a phase difference detected by the current / velocity phase difference detection unit 35 exceeding a predetermined allowable value at a rate of once every several hundred cycles of the reciprocation of the pistons 12a and 12b. Determine if you are. If it is determined that the phase difference exceeds the allowable value, it is further determined whether or not the phase difference exceeds a predetermined excess determination criterion.
[0039]
When it is determined that the phase difference exceeds a predetermined excess determination criterion, the angular frequency ω is corrected so that the drive frequency approaches the resonance frequency. Then, the magnitude relationship between the maximum amplitude current value Anow and a predetermined reference amplitude (position) is determined.
[0040]
When it is determined that the maximum current amplitude value Anow is larger than the predetermined reference amplitude and smaller than the maximum amplitude target value Aref, that is, when the maximum amplitude current value Anow exceeds the predetermined reference amplitude, the current command value The value of the current gain Gi used in the generation unit is decreased by a predetermined rate. On the other hand, when the maximum current amplitude value Now does not exceed a predetermined reference amplitude, the process of decreasing the value of the current gain Gi is not performed.
[0041]
Further, when it is determined that the phase difference exceeds the predetermined allowable value but does not exceed the predetermined excess determination criterion, the minimum resolution by the position command value generation unit 30 without decreasing the current gain Gi. The frequency changing process is executed.
[0042]
In this embodiment, two-stage determination criteria are set as will be described later as a predetermined excess determination criterion for the phase difference.
[0043]
The current command value generation unit 32 generates a current command value Iref based on the speed control value Vc generated by the position / speed control unit 31, the current gain Gi, and the formula Iref = Gi × Vc. Further, the current command value Iref is converted into a control signal φc and supplied to the motor driver 3. Control of the output current I of the motor driver 3 is performed, for example, by the PWM method.
[0044]
In the control circuit 5 described above, a position command value Pref is first generated by the position command value generation unit 30, a speed control value Vc is generated by the position / speed control unit 31, In the current command value generation unit 32 A control signal φc is generated. When a current is supplied from the motor driver 3 to the coil 23 of the linear motor 20, the movable part of the linear motor 20 starts a reciprocating motion and gas compression is started.
[0045]
Next, a specific control procedure of the control circuit 5 will be described based on the flowcharts shown in FIGS. First, in step S0, a data extraction interval extension value for sequentially extracting data from the sign table is calculated.
[0046]
Next, in step S1, the position / velocity detection unit 33 reads the position data Pa. In step S2, the position / velocity detection unit 33 calculates the current position value Pnow and the current speed value Vnow.
[0047]
In step S <b> 3, the position / speed control unit 31 performs speed control. That is, the position / speed control unit 31 generates the speed control value Vc based on the deviation between the speed command value Vref and the current speed value Vnow and supplies the speed command value Vc to the current command value generation unit 32.
[0048]
In step S4, the current command value generation unit 32 generates a current command value Iref that is the product of the speed control value Vc and the current gain Gi. In step S <b> 5, current command data corresponding to the current command value Iref, that is, a control signal φc is output from the current command value generation unit 32 to the motor driver 3.
[0049]
In step S6, the control circuit 5 The counter value of a first counter (not shown) included in the counter is incremented (+1). In step S7, it is determined whether or not the count value of the first counter has reached a set value (3 in the present embodiment).
[0050]
If it is determined in step S7 that the count value of the first counter has reached the set value, the process proceeds to step S8. In step S8, the position command value generation unit 30 generates the amplitude A and the angular frequency ω based on the position correction amount and the frequency setting value. Further, a position command value Pref = Asinωt + B is generated based on the sine table data, the amplitude A, the shift amount B, and the angular frequency ω.
[0051]
Next, in step S <b> 9, position control is performed by the position / speed control unit 31. That is, the position / speed control unit 31 generates the speed command value Vref based on the deviation between the position command value Pref and the current position value Pnow. After the position control is completed, the process proceeds to step S10 and the count value of the first counter is reset.
[0052]
If it is determined in step S7 that the count value of the first counter has not reached the set value, steps S8 to S10 are not executed.
[0053]
Next, in step S11, By the position / speed detector 33 It is determined whether one cycle of the position command value Pref has been completed. This determination can be replaced with a determination of whether the current position value has zero-crossed from a negative value to a positive value.
[0054]
If it is determined in step S11 that one cycle of the position command value Pref has been completed, the process proceeds to step S12. In step S12, the top dead center side amplitude and the bottom dead center side of the pistons 12a and 12b based on the maximum and minimum values of the current position value Pnow obtained from the position / velocity detection unit 33 by the vertical dead center detection unit 34 The amplitude is calculated.
[0055]
Next, in step 13, By the amplitude neutral position control means 37 When the magnitude relationship between the top dead center side amplitude and the bottom dead center side amplitude is compared, and it is determined that the top dead center side amplitude is greater than the bottom dead center side amplitude, the process proceeds to step S14. In step S <b> 14, a negative correction amount is set as the correction amount of the shift amount B by the amplitude neutral position control unit 37. Next, in step S15, the top dead center side amplitude is set as the maximum current amplitude value Now.
[0056]
If the result of the magnitude comparison between the top dead center side amplitude and the bottom dead center side amplitude in step S13 indicates that the bottom dead center side amplitude is greater than the top dead center side amplitude, the process proceeds to step S16. . In step S <b> 16, a positive correction amount is set as the correction amount of the shift amount B by the amplitude neutral position control unit 37. In step S17, the bottom dead center side amplitude is set as the maximum amplitude current value Now.
[0057]
Next, in step S18, the current gain Gi is controlled and set by the current gain controller 36 so that the maximum amplitude current value Anow matches the maximum amplitude target value Aref. In step S <b> 19, the maximum and minimum values of the current position value Pnow are reset in the vertical dead center detection unit 34.
[0058]
If it is determined in step S11 that one cycle of the position command value Pref is not completed, steps S12 to S19 are not executed. Next, in step S20, the upper and lower dead center detector 34 detects and holds the maximum value and the minimum value of the current position value Pnow.
[0059]
In step S21, By the position / speed detector 33 It is determined whether or not one cycle of the current position value Pnow has been completed. This determination can be replaced with a determination of whether the current position value has zero-crossed from a negative value to a positive value. If it is determined in step S21 that one cycle of the current position value Pnow has been completed, the process proceeds to step S22. In step S22, the phase difference between the current command value Iref and the current speed value Vnow is detected by the current / speed phase difference detector 35.
[0060]
In step S23, the count value of a second counter (not shown) is incremented. Next, in step S24, it is determined whether or not the count value of the second counter has reached a set value (for example, 300). If it is determined in step S24 that the count value of the second counter has reached the set value, the process proceeds to step S25.
[0061]
In step S25, By the current / speed phase difference detector 35 It is determined whether or not the phase difference between current command value Iref and current speed value Vnow is within an allowable value. If it is determined in step S25 that the phase difference is not within the allowable value, the process proceeds to step S26.
[0062]
In step S26, it is determined whether or not the phase difference exceeds the first excess determination criterion. If it is determined in step S26 that the phase difference does not exceed the first excess determination criterion, the process proceeds to step S27.
[0063]
In step S27, it is determined whether or not the phase difference exceeds a second excess determination criterion that is smaller than the first excess determination criterion. If it is determined in step S27 that the phase difference does not exceed the second excess determination criterion, the process proceeds to step S28.
[0064]
In step S28, By the frequency control unit 38 A procedure is performed to change the piston drive frequency by a minimum resolution. Specifically, a procedure for updating the data extraction interval extension value by adding 1 to the data extraction interval extension value when increasing the frequency and subtracting 1 from the data extraction interval extension value when decreasing the frequency is executed. The Next, in step S29, the count value of the second counter is reset.
[0065]
If it is determined in step S21 that one cycle of the current position value Pnow has not ended, steps S22 to S29 are not executed.
[0066]
If it is determined in step S24 that the count value of the second counter has not reached the set value, steps S25 to S29 are not executed. If it is determined in step S25 that the phase difference is within the allowable value, steps S26 to S28 are not executed.
[0067]
If it is determined in step S26 that the phase difference exceeds the first excess determination criterion, the process proceeds to step S33. In step S33, the frequency change amount is set to a large value (for example, 0.15 Hz), and frequency control / setting is executed.
[0068]
Next, in step S34, By the amplitude neutral position control unit 37 It is determined whether or not the piston amplitude exceeds a predetermined reference amplitude (reference position). In step S34, as shown in FIG. 6, when it is determined that the amplitude of the piston exceeds the reference position, the process proceeds to step S35. In step S35, By the current gain control unit 36 The current gain of the current command value is reduced by a predetermined value (for example, 30%), and the process proceeds to step S29.
[0069]
If it is not determined in step S34 that the piston amplitude exceeds the reference position, that is, as shown in FIG. 7, if the piston amplitude is smaller than the reference position, step S35 is not executed and the process proceeds to step S29. To do.
[0070]
In Step S27, when it is determined that the phase difference exceeds the second excess reference, the process proceeds to Step S30. In step S30, the frequency change amount is set to a small value (for example, 0.03 Hz), and frequency control / setting is executed.
[0071]
Next, in step S31, By the amplitude neutral position control unit 37 It is determined whether the amplitude of the piston exceeds a predetermined reference position. As shown in FIG. 6, when it is determined that the amplitude of the piston exceeds a predetermined reference position, the process proceeds to step S32. In step S32, By the current gain control unit 36 The current gain of the current command value is reduced by a predetermined value (for example, 15%), and the process proceeds to step S29.
[0072]
In step S31, as shown in FIG. 7, when the amplitude of the piston does not exceed the predetermined reference position, step S32 is not executed and the process proceeds to step S29.
[0073]
Next, in step S36, it is determined whether or not the control should be terminated due to the operation stop of the linear compressor or the like. If it is determined that the control should be terminated, the procedure is terminated. On the other hand, if it is determined that the control should not be terminated, the process returns to step S1 and the above-described control is repeated.
[0074]
According to the flowchart described above, when the phase difference between the current and the speed is within the allowable value range, the drive frequency changing process is not performed, but when the phase difference is not within the allowable value range, that is, the drive frequency. Is shifted from the resonance frequency, the drive frequency is changed. At this time, a predetermined current gain reduction process is performed along with the change of the driving frequency.
[0075]
That is, as described in steps S31 and S34, when it is determined that the piston amplitude exceeds the predetermined reference position, the current gain is reduced. On the other hand, when the piston amplitude does not exceed the reference position, the current gain is not reduced.
[0076]
In this way, when the drive frequency is changed, if the piston amplitude does not exceed the reference position, the current gain is not reduced, so that when the drive frequency is changed repeatedly, the piston stroke is reduced. It will not be smaller than necessary. Then, when the drive frequency falls within the allowable range of the resonance frequency, the current gain is controlled so that the piston amplitude matches the target amplitude without changing the drive frequency, so that the piston It is possible to return quickly to the amplitude of.
[0077]
As a result, it is possible to prevent the discharge gas amount from being greatly reduced and the efficiency of the linear compressor from being lowered. Further, the vicinity of the reference position becomes the minimum value of the piston stroke, and the driving can be performed in the vicinity of the target stroke.
[0078]
In the above embodiment, the current gain is decreased by a predetermined ratio in order to decrease the amplitude of the piston. However, for example, the value of the sine table as a position function is decreased by a predetermined ratio. May be.
[0079]
In the above-described embodiment, a two-piston type linear compressor has been described as an example, but even when applied to a one-piston type, the stroke of the piston is prevented from becoming unnecessarily small. Therefore, it is possible to prevent the discharge gas amount from being greatly reduced, and it is possible to perform a highly efficient operation of the linear compressor.
[0080]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0081]
【The invention's effect】
According to the drive control device for a linear compressor according to the present invention, when the drive frequency is adjusted to the target resonance frequency in the frequency control means, when the piston amplitude exceeds a predetermined reference amplitude smaller than the target amplitude, Amplitude reduction processing for reducing the piston amplitude is performed. If the piston amplitude does not exceed a predetermined reference amplitude, the amplitude reduction processing is not performed. If the drive frequency falls within the allowable range of the resonance frequency, the drive frequency is not changed, and the piston amplitude is adjusted to the target amplitude. Thus, even when the process of bringing the drive frequency close to the resonance frequency is repeated, the piston amplitude (stroke) does not become unnecessarily small. As a result, it is possible to prevent the efficiency of the linear compressor from being lowered due to a decrease in gas discharge amount.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a drive control apparatus for a linear compressor according to an embodiment of the present invention.
FIG. 2 is a block diagram of a control circuit in the drive control device in the embodiment.
FIG. 3 is a cross-sectional view showing the structure of the linear compressor in the same embodiment.
FIG. 4 is a flowchart showing the first half of the control procedure of the control circuit in the same embodiment;
FIG. 5 is a flowchart showing the second half of the control procedure of the control circuit in the same embodiment;
FIG. 6 is a first graph showing the displacement of the piston in the same embodiment.
FIG. 7 is a second graph showing the displacement of the piston in the same embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Linear compressor, 2 Drive control apparatus, 3 Motor driver, 4 Displacement sensor, 5 Control circuit, 11a, 11b Cylinder, 12a, 12b Piston, 20 Linear motor.

Claims (5)

A current command means for generating a current command value according to a position function serving as a reference for the position of the piston, and generating a drive current according to the current command value;
Position detecting means for detecting the position of the piston in the cylinder;
Amplitude detecting means for detecting the amplitude of the piston in the cylinder;
Frequency control means for adjusting the drive frequency to a target resonance frequency;
Based on the amplitude of the piston detected by the amplitude detection means, the amplitude control means for matching the amplitude of the piston with a predetermined target amplitude,
In the frequency control means, when the drive frequency is not within the range of the allowable value of the target resonance frequency, processing for adjusting the drive frequency to the target resonance frequency is performed, and the drive frequency is within the range of the allowable value. Is not performed to match the drive frequency to the target resonance frequency,
In the amplitude control means, when the drive frequency is adjusted to a target resonance frequency in the frequency control means, the piston amplitude detected by the amplitude detection means is a predetermined reference amplitude smaller than the target amplitude. If it exceeds, an amplitude reduction process for reducing the amplitude of the piston is performed, and if the amplitude of the piston does not exceed the predetermined reference amplitude, the amplitude reduction process is not performed. Control device. The linear compressor drive control device according to claim 1, wherein the amplitude reduction process includes a process of reducing the current command value generated by the current command unit to a predetermined ratio. The linear compressor drive control apparatus according to claim 1, wherein the amplitude reduction process includes a process of reducing the amplitude of the position function to a predetermined ratio. Speed detecting means for detecting the speed of the piston in the cylinder;
A phase difference detection means for detecting a phase difference between the current command value generated by the current command means and the speed detected by the speed detection means;
With
The drive control apparatus for a linear compressor according to any one of claims 1 to 3, wherein the frequency control means controls the frequency of the position function so that the phase difference detected by the phase difference detection means is eliminated. In the amplitude detection means, the top dead center side amplitude corresponding to the length between the top dead center of the piston and the origin based on the detection result of the position detection means, and the bottom dead center between the piston bottom dead center and the origin. The bottom dead center amplitude corresponding to the length is detected,
In the amplitude control means, the larger one of the top dead center side amplitude and the bottom dead center side amplitude detected by the amplitude detection means is controlled so as to coincide with the predetermined target amplitude. The drive control apparatus of the linear compressor in any one of Claims 1-4.

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