KR100414095B1 - Top dead center control apparatus for reciprocating compressor - Google Patents

Abstract

The present invention relates to a TDC control apparatus and method for a reciprocating compressor, and detects the phase difference between the stroke and the current, and changes the operating frequency so that the stroke length of the piston is near 'TDC = 0' for each load change, thereby improving operation efficiency. It is to improve. To this end, the present invention includes a detection means for detecting a phase difference between the motor current and the current piston stroke; Frequency determining means for determining an operating frequency in accordance with the phase difference; TDC command value determining means for determining a TDC command value by the driving frequency; Control means for comparing the TDC command value with the current piston TDC and outputting a TDC control signal accordingly; And a frequency varying means for varying a voltage applied to the motor by varying an operating frequency by the TDC control signal.

Description

TDC control device and method of reciprocating compressor {TOP DEAD CENTER CONTROL APPARATUS FOR RECIPROCATING COMPRESSOR}

The present invention relates to a TDC control apparatus and method for a reciprocating compressor, and more particularly, to a TDC control apparatus and method for a reciprocating compressor to vary the operating frequency by employing an inverter.

In general, a reciprocating compressor generates a torque by interrupting the power supplied to a coil wound around a multi-phase stator by using a switching element. By sequentially changing the excitation state between the rotor and the stator, The forward rotational torque can be generated by the suction force.

1 is a block diagram showing a configuration of an operation control device of a general reciprocating compressor. As shown in FIG. 1, the piston changes the stroke in vertical motion by the voltage applied to the internal motor according to the stroke command value. A reciprocating compression unit (L.COMP) for adjusting; A voltage detector (30) which detects a voltage generated in the reciprocating compression section (L.COMP) as the stroke is increased by an applied voltage; A current detector 20 which detects a current applied to the reciprocating compressor L.COMP as the stroke is increased by an applied voltage; A microcomputer (40) for calculating a stroke from the voltage and current detected by the voltage detector (30) and the current detector (20), comparing the stroke with a stroke command value, and outputting a switching control signal accordingly; In accordance with the switching control signal of the microcomputer 40, it consists of an electrical circuit section 10 for interrupting the AC power to the triac (Tr1) to apply a voltage to the reciprocating compression section (L.COMP), and thus The operation of the conventional apparatus will be described.

First, the reciprocating compression section (L.COMP), the piston is moved up and down by the applied voltage according to the stroke command value set by the user, thereby the stroke is variable to adjust the cooling force.

Meanwhile, the stroke of the triac Tr1 of the electric circuit unit 10 is increased due to a long turn-on period due to the switching control signal of the microcomputer 40, wherein the motor M of the reciprocating compressor L.COMP is increased. The voltage and the current applied to the) are detected by the voltage detector 30 and the current detector 20, and applied to the microcomputer 40.

Then, the microcomputer 40 calculates a stroke using the applied voltage and current detected from the voltage detector 30 and the current detector 20, and compares the stroke with the stroke command value and accordingly switches the control signal. Outputs

That is, when the calculated stroke is smaller than the stroke command value, the microcomputer 40 outputs a switching control signal for lengthening the on-cycle of the triac Tr1, thereby converting the voltage applied to the reciprocating compressor L.COMP. Increase.

Unlike the above, when the calculated stroke is larger than the stroke command value, the microcomputer 40 outputs a switching control signal for shortening the on-cycle of the triac Tr1 and is applied to the reciprocating compression unit L.COMP. Reduce the voltage.

However, since the reciprocating compressor operating as described above has a nonlinearity in which the mechanical motion characteristics are severe, there is a problem that precise control is impossible with a linear control method that does not take into account the nonlinearity.

In order to solve this problem, the reciprocating compressor improves the operating efficiency by controlling the operation so that the phase difference between the current and the stroke is the same.However, when the reciprocating compressor is continuously operated, the operating efficiency is increased due to the load variation according to the change of the surrounding environment. There is a problem of deterioration.

The present invention has been made to solve the above problems, by detecting the phase difference between the stroke and the current, by varying the operating frequency so that the stroke stroke of the piston is close to 'TDC = 0' for each load change, improving the operating efficiency It is an object of the present invention to provide a TDC control apparatus and method for a reciprocating compressor.

1 is a circuit diagram showing the configuration of a TDC control apparatus of a general reciprocating compressor.

Figure 2 is a block diagram showing the configuration of the TDC control device of the reciprocating compressor of the present invention.

Figure 3 is an operation flowchart of an embodiment of a TDC control method of the reciprocating compressor of the present invention.

4 is a view showing a stable operation region in FIG.

FIG. 5 shows a relationship between frequency and load in FIG. 3; FIG.

FIG. 6 shows the movement of the inflection point of the phase difference with increasing load in FIG.

FIG. 7 shows the movement of the phase difference inflection point in the case of increasing the frequency at a certain load in FIG.

8 is a diagram showing the increase and decrease of the operating frequency according to the magnitude of the load in FIG.

9 is an operation flowchart of an embodiment of a TDC control method of the reciprocating compressor according to the present invention;

10 is a flowchart illustrating an embodiment of a TDC control method of the reciprocating compressor according to the present invention.

** Explanation of symbols for main parts of drawings **

100: current detection unit 200: phase difference detection unit

300,801: comparator 400: safety zone storage

500: Operation frequency determiner 600: TDC command value determiner

700: frequency / TDC storage 800: control

900: inverter

The present invention for achieving the above object comprises: detecting means for detecting a phase difference between the motor current and the current piston stroke; Frequency determining means for determining an operating frequency in accordance with the phase difference; TDC command value determining means for determining a TDC command value by the driving frequency; Control means for comparing the TDC command value with the current piston TDC and outputting a TDC control signal accordingly; And a frequency varying means for varying a voltage applied to the motor by varying an operating frequency by the TDC control signal.

The present invention for achieving the above object, the first process for detecting a load change while driving at a reference operating frequency; A second process of detecting an operating frequency in a stable region by adding or subtracting the reference operating frequency when a load change is detected; After determining the TDC command value corresponding to the operating frequency of the stable region, and performing a third process of controlling the TDC according to the TDC command value.

The present invention for achieving the above object, the first process for detecting the inflection point of the phase difference with respect to the piston stroke and the motor current while increasing the TDC setpoint; Setting a piston TDC at an inflection point for the phase difference between the piston stroke and the current to a TDC command value, and then detecting a load change; A third step of, if a load change is detected, subtracting or reducing a reference operating frequency, reducing the TDC command value by a predetermined value, and then feeding back to the first step; If a load change is not detected, the fourth process of controlling the TDC of the piston according to the set TDC command value is performed.

The present invention for achieving the above object comprises a first step of determining whether the current piston TDC is detected after the inflection point for the phase difference between the motor current and the stroke; A second process of comparing the magnitude of the piston TDC with the TDC command value at the time of the inflection point when the piston TDC is detected after the inflection point is generated, thereby increasing or decreasing the input of the compressor; ; As a result of the determination of the first process, if the piston TDC is detected before the inflection point occurs, it is performed as a third process of comparing the magnitude of the piston TDC and the current TDC command value to increase or decrease the input of the compressor accordingly. do.

Hereinafter, the operation and effects of the TDC control apparatus and method of the reciprocating compressor according to the present invention will be described in detail with reference to the accompanying drawings.

Fig. 2 is a block diagram showing an embodiment of a TDC control apparatus of the reciprocating compressor of the present invention, and as shown therein, a current detecting unit 100 for detecting a current flowing in a motor; TDC detection unit 101 for detecting the current piston TDC through a sensor built into the motor; A phase difference detection unit 200 for detecting a phase difference by receiving a piston stroke detected through a sensor embedded in a motor and the motor current of the current detection unit 100; A stable region storage unit 400 which detects and stores a phase difference stable region for performing stable operation through an experiment; A comparator (300) for comparing whether the phase difference of the phase difference detector (200) is included in the phase difference stable region; When the reference operating frequency is added or subtracted by a predetermined frequency unit and the phase difference between the current and the piston stroke enters the stable region, the operating frequency determiner 500 determines the frequency at that time as the operating frequency according to the comparison signal of the comparator 300. Wow; A TDC command value determiner (600) which determines a TDC command value by an operating frequency output from the driving frequency determiner (500); By experiment, the frequency / TDC storage unit 700 for storing the piston TDC for each operating frequency; A control unit 800 for comparing the TDC command value with the current piston TDC and outputting a TDC control signal according thereto; In accordance with the TDC control signal of the control unit 800, an inverter 900 for varying the operating frequency to vary the voltage applied to the motor, the operation of the present invention configured as described above will be described.

First, the invention is to detect the inflection point of the phase difference (PHASE_CS) between the piston stroke and the current, and to vary the operating frequency so that the motor is driven in the stable region including the point where TDC = 0 as shown in Figure 4, that is, the current detection unit 100 detects the current applied to the motor and applies it to the phase difference detection unit 200, and the TDC detection unit 101 detects the piston TDC through a sensor built in the motor.

Here, the phase difference detection unit 200, in addition to the phase difference (PHASE_CS) of the piston stroke and the current detected through the sensor built into the motor, the power supply voltage (220V / 60Hz, 220V / 50Hz, 110V / 60Hz, 110V / 50Hz) and The phase difference with respect to the motor current, the phase difference between the motor current and the motor voltage, or the phase difference between the piston acceleration and the motor current, or the phase difference between the piston speed and the motor current is detected to control the operation to be 'TDC = 0'.

At this time, the stable region storage unit 400, in advance through the experiment, when the mechanical resonance is the motor current and the piston speed or motor current and piston acceleration or the motor current and the piston stroke or the motor current and the motor voltage and ± delta relative to the phase difference between the motor current and the motor voltage Area within (predetermined value) is detected and stored.

The comparator 300 receives the phase difference PHASE_CS of the piston stroke of the phase difference detecting unit 200 and the current and compares the phase difference PHASE_CS to the safety area of the stable area storage unit 400 to compare the phase difference PHASE_CS. The comparison signal is applied to the driving frequency determiner 500.

Accordingly, the driving frequency determiner 500 adds or subtracts the reference driving frequency by a predetermined frequency unit, and when the phase difference PHASE_CS of the current and the piston stroke enters the stable region, the comparison signal of the comparator 300 determines the operation frequency. The frequency of the time point is determined as an operating frequency and applied to the TDC command value determiner 600.

Accordingly, the TDC command value determiner 600 determines the TDC command value by the driving frequency output from the driving frequency determiner 500.

That is, by experiment, the piston TDC for each frequency is stored in the frequency / TDC storage unit 700, by reading the piston TDC corresponding to the operating frequency output from the operating frequency determiner 500 is determined as the TDC command value do.

Thereafter, the controller 800 receives the TDC command value output from the TDC command value determiner 600, compares the TDC command value with the piston TDC of the TDC detector 101, and outputs a TDC control signal accordingly, that is, a comparator. 801 compares the TDC command value and the piston TDC and outputs the difference value, and the TDC control unit 802 applies the corrected TDC control signal to the inverter 900 by the difference value.

Accordingly, the inverter 900 varies the operating frequency by the TDC control signal of the controller 800 to change the voltage applied to the motor.

More specifically, referring to FIG. 3, the load fluctuation is detected while operating at the reference operating frequency (SP1, SP2), and the load fluctuation includes the phase difference PHASE_CS between the piston stroke and the motor current in a predetermined stable region section. Whether or not the phase difference between the piston acceleration or the piston speed and the motor current is included in the predetermined stable region, or whether the phase difference between the motor voltage and the motor current is included in the predetermined stable region. Detect by

At this time, as shown in Figure 5, when the piston TDC is constant, if the load increases the operating point moves from 'A' to 'B', if the load decreases from 'A' to 'C'.

In addition, as shown in Fig. 6, when the driving frequency is constant, when the load increases, the inflection point of the phase difference PHASE_CS between the piston stroke and the current moves above the stable region.

Therefore, when the load variation is detected, the reference frequency is added or subtracted to detect the operating frequency in the stable region (SP3 to SP7).

That is, if the phase difference PHASE_CS between the current and the piston stroke is greater than the upper limit phase difference between the stable region, as shown in Fig. 7, the operating frequency is increased (SP4), and the phase difference PHASE_CS between the current and the piston stroke is equal to the stable region. If it is smaller than the lower limit phase difference, the driving frequency is decreased (SP5), and then the operating frequency is determined by determining whether the added or decreased operating frequency is included in each stable region section (SP6, SP7).

Next, after determining the TDC command value corresponding to the operating frequency of the stable region (SP8), TDC control is performed according to the TDC command value (SP9).

Here, a stable area for performing stable operation is detected and stored in advance through experiments, and a TDC for each driving frequency is detected and stored.

Referring to FIG. 8, the operation frequency variable operation according to the load variation will be described. When the constant piston TDC operation is performed at the current operating point, the load variation is not severe, and the operation is performed when the phase difference PHASE_CS between the piston stroke and the current is within the safe region. If the load increases and becomes larger than the stable region without changing the frequency, the operating frequency is moved in the solid line direction, and when the load decreases and becomes smaller than the stable region, the operating frequency is moved in the dotted line direction.

Fig. 9 is an operation flowchart of another embodiment of the reciprocating compressor of the present invention, after operating the reciprocating compressor at the reference operating frequency, and detecting the inflection point of the phase difference (PHASE_CS) with respect to the piston stroke and the motor current while increasing the TDC command value ( SP11 to SP13), the process of increasing the TDC command value is repeated until the inflection point of the phase difference PHASE_CS between the piston stroke and the motor current is detected.

If an inflection point for the phase difference PHASE_CS between the piston stroke and the current is detected, the piston TDC at the inflection point is set to the TDC command value (SP14), and the load fluctuation is detected (SP15).

Then, when the load variation is detected, it is determined whether the load is increased or decreased (SP16), and accordingly the reference operating frequency is adjusted (SP17, SP18), so that the phase difference (PHASE_CS) between the current and the piston stroke is the upper limit of the stable region. If it is larger than the phase difference, the operating frequency is increased (SP17). If the phase difference (PHASE_CS) between the current and the piston stroke is smaller than the lower limit phase difference of the stable region, the operating frequency is decreased (SP18).

Then, the TDC command value is decreased by a predetermined value (SP19), and the operation is repeatedly performed. The predetermined value is experimentally used to easily detect an inflection point for the phase difference PHASE_CS between the piston stroke and the current. Set it.

Here, in addition to the phase difference PHASE_CS between the piston stroke and the current, the phase difference between the piston speed and the current, the phase difference between the piston acceleration and the current, and the phase difference between the voltage and the current may be used.

10 is a flowchart of another embodiment of the TDC control method of the reciprocating compressor of the present invention, and it is determined whether the current piston TDC has been detected after the inflection point for the phase difference PHASE_CS of the motor current and the piston stroke has occurred (SP21, FIG. SP22).

As a result of the determination, when the piston TDC is detected after the inflection point is generated, the magnitude of the TDC command value at the inflection point occurrence of the phase difference PHASE_CS between the piston stroke and the motor current is compared (SP23), thereby increasing or decreasing the input of the compressor. (SP25, SP26)

That is, if the piston TDC is larger than the TDC command value at the inflection point of the phase difference (PHASE_CS) between the piston stroke and the motor current, the compressor input is reduced (SP26), and the piston TDC is the inflection point of the phase difference (PHASE_CS) between the piston stroke and the motor current. If it is smaller than the TDC command value at the time of occurrence, the input of the compressor is increased (SP25).

If the piston TDC is detected before the inflection point of the phase difference PHASE_CS between the piston stroke and the motor current occurs, the magnitude of the piston TDC and the current TDC setpoint is compared (SP24), thereby increasing or decreasing the input of the compressor. (SP25, SP26).

That is, if the piston TDC is larger than the current TDC setpoint, the input of the compressor is reduced (SP26). If the piston TDC is smaller than the current TDC setpoint, the input of the compressor is increased (SP25).

Here, in addition to the phase difference PHASE_CS between the piston stroke and the current, the phase difference between the piston speed and the current, the phase difference between the piston acceleration and the current, and the phase difference between the voltage and the current may be used.

As described in detail above, the present invention has the effect of improving the operating efficiency by controlling the TDC by varying the operating frequency so that the stroke distance of the piston, which is the resonance frequency region, is around 'TDC = 0'.

Claims (18)

Detecting means for detecting a phase difference between the motor current and the current piston stroke; Frequency determining means for determining an operating frequency in accordance with the phase difference; TDC command value determining means for determining a TDC command value by the driving frequency; Control means for comparing the TDC command value with the current piston TDC and outputting a TDC control signal accordingly; And a frequency variable means for varying a voltage applied to the motor by varying an operating frequency by the TDC control signal. According to claim 1, wherein the frequency determining means, Stable region storage means for detecting and storing a phase difference stable region for performing a stable operation through an experiment; And a comparison means for comparing whether or not the phase difference of the detection means is included in the phase difference stable region. The frequency determining means according to claim 1 or 2, A TDC control apparatus for a reciprocating compressor, characterized in that the reference operating frequency is added or subtracted by a predetermined frequency unit, and when the phase difference between the current and the stroke enters the stable region, the frequency at that time is determined as the operating frequency. The method of claim 3, wherein the frequency determining means, And a driving frequency is increased when the phase difference between the current and the stroke is greater than the upper limit phase difference in the stable region. The method of claim 3, wherein the frequency determining means, TDC control apparatus of the reciprocating compressor characterized by reducing an operating frequency, when the phase difference of an electric current and a stroke is smaller than the lower limit phase difference of a stable area. The method of claim 1, wherein the TDC command value determining means, Experimentally, the TDC control apparatus of the reciprocating compressor, characterized in that it comprises a means for storing the TDC for each operating frequency. The method of claim 1, wherein the frequency variable stage, TDC control device of a reciprocating compressor, characterized in that the inverter to change the DC voltage to AC voltage. The method of claim 7, wherein the inverter, TDC control device of a reciprocating compressor characterized in that the single-phase inverter that changes the DC voltage into a single-phase AC voltage. A first step of detecting a load change while driving at a reference operating frequency; A second process of detecting an operating frequency in a stable region by adding or subtracting the reference operating frequency when a load change is detected; And determining a TDC command value corresponding to the operating frequency of the stable region, and then performing a third process of controlling the TDC according to the TDC command value. 10. The method of claim 9, comprising detecting and storing a phase difference stable region for performing stable operation. 10. The method of claim 9, comprising storing the TDC for each operating frequency. The method of claim 9, wherein the second process comprises: Increasing the operating frequency if the phase difference between the current and the piston stroke is greater than the upper limit phase difference between the stable region sections; If the phase difference between the current and the piston stroke is smaller than the lower limit phase difference between the stable region sections, reducing the operating frequency; And determining the operating frequency by determining whether the subtracted driving frequency is included in each stable region section. A first step of detecting an inflection point of the phase difference with respect to the piston stroke and the motor current while increasing the TDC setpoint; Setting a piston TDC at an inflection point for the phase difference between the piston stroke and the current to a TDC command value, and then detecting a load change; A third step of, if a load change is detected, subtracting or reducing a reference operating frequency, reducing the TDC command value by a predetermined value, and then feeding back to the first step; If the load change is not detected, the TDC control method of the reciprocating compressor, characterized in that the fourth step of controlling the TDC of the piston in accordance with the set TDC command value. The method of claim 13, wherein the predetermined value is, TDC control method of a reciprocating compressor, characterized in that it is set to facilitate the detection of the inflection point for the phase difference between the piston stroke and the current through the experiment. The method of claim 13, wherein the third process comprises: Increasing the operating frequency if the phase difference between the current and the piston stroke is greater than the upper limit phase difference in the stable region; And if the phase difference between the current and the piston stroke is smaller than the lower limit phase difference in the stable region, reducing the operating frequency. A first step of determining whether the current piston TDC is detected after an inflection point for the phase difference between the motor current and the piston stroke occurs; A second process of comparing the magnitude of the piston TDC with the TDC command value at the time of the inflection point when the piston TDC is detected after the inflection point is generated, thereby increasing or decreasing the input of the compressor; ; As a result of the determination of the first process, if the piston TDC is detected before the inflection point occurs, it is performed as a third process of comparing the magnitude of the piston TDC and the current TDC command value to increase or decrease the input of the compressor accordingly. TDC control method of a reciprocating compressor. The method of claim 16, wherein the second process comprises: Reducing the input of the compressor if the piston TDC is greater than the TDC command value at the time of inflection point generation; And increasing the input of the compressor if the piston TDC is smaller than the TDC command value at the time of inflection point generation. The method of claim 16, wherein the third process, Reducing the input of the compressor if the piston TDC is greater than the current TDC setpoint; And increasing the input of the compressor if the piston TDC is less than the current TDC setpoint.