JPH09201086A - Control apparatus for compressor of air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a control apparatus by which the operating efficiency of a compressor as an object to be controlled can be controlled at a small current without setting the compressor to an unstable state by a method wherein an output voltage is adjusted in such a way that either an output current value or a power value is made minimum according to a power value in an inverter circuit. SOLUTION: The speed of rotation of a compressor 7 is controlled to a prescribed target value by a frequency control means, and the output voltage of an inverter circuit 1 is controlled. Thereby, either a power value or a current value is made minimum according to the change amount of power or the absolute value of power in the inverter circuit 1, and the compressor 7 is controlled. In addition, the increase or decrease direction of a voltage in the start of the control of a minimization processing operation is set correctly by an optimum- slip-amount storage means 11 in which the speed of rotation and the slip amount of the compressor 7 are stored at a time when the power value or the current value is made minimum, and a minimization control and processing operation 12 is performed in a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor control device for controlling the operation of an induction motor for a compressor which is driven at a variable speed by an inverter device in an air conditioner.

[0002]

2. Description of the Related Art A conventional compressor control device for an air conditioner is
The induction motor is driven at a variable speed by an inverter device, and Japanese Patent Application Laid-Open No. 57-67735 discloses such a compressor control device. JP-A-57-677
In the control device disclosed in Japanese Patent Laid-Open No. 35-35, the induction motor is controlled according to an operation pattern in which the output voltage v of the inverter device and the output frequency f have a constant ratio v / f. Generally, the ratio v / f of the output voltage v and the output frequency f of the inverter device is:
It is set to maximize operating efficiency. The high operating efficiency means driving the induction motor to be controlled with the minimum inverter output power under a constant load condition. Therefore, when the induction motor is driven with an overload or a low load, a large motor slip etc. occurs,
The induction motor was operating with low operating efficiency.

Various control devices have been developed for the purpose of solving such problems. For example, JP
A control method for an air conditioner disclosed in Japanese Patent Laid-Open No. 2-152394 detects an output power of an inverter device and changes an output voltage while keeping a constant output frequency of the inverter device so that the output power is minimized. ing. And
The air conditioner of the preceding example is intended to operate the induction motor with high operation efficiency by changing the output voltage. Further, the AC motor control device disclosed in Japanese Patent Application Laid-Open No. 62-89493 detects the current of the AC motor and keeps the output frequency of the inverter device constant so that the current value is minimized. By changing the output voltage, an attempt was made to operate with good operation efficiency. Further, in the compressor operation control method disclosed in JP-A-6-78582, the target rotation speed of the compressor is set to a predetermined rotation speed so as to increase the operation efficiency of the compressor. The operation efficiency of the equipment incorporating this compressor was improved. The control methods disclosed in these publications control the inverter device in order to maximize the operating efficiency at that time in consideration of the load state of the compressor. Further, in order to eliminate the disturbance phenomenon in which the rotation is disturbed in the conventional compressor, there is disclosed in Japanese Patent Laid-Open No. 61-735
Japanese Patent Laid-Open No. 92-92 discloses a control that detects a change in current in a direct current section, determines a disturbance phenomenon by the switching mode of powering and regeneration, and increases or decreases the frequency at the switching timing to suppress the disturbance phenomenon. It had been.

[0004]

Problems to be Solved by the Invention JP-A-62-1523
In the air conditioner control method disclosed in Japanese Patent Laid-Open No. 94 or the AC motor control device disclosed in Japanese Patent Laid-Open No. 62-89493, when a control method that minimizes the actual electric power value of the electric motor is used, the load is When the output voltage was low, the power value remained almost unchanged even when the output voltage was changed, and there was a region where the operating efficiency did not change. In addition, when such a load is low, the current value may increase a little depending on how the output voltage is set. In addition, when a control method that minimizes the electric current value of the electric motor is used, the time when the electric current value is minimum does not match the time when the electric motor has the highest operating efficiency. Could not be maximized substantially. Further, in the compressor operation control method disclosed in JP-A-6-78582, the target rotation speed of the compressor is set in advance, and there is a problem in that it cannot cope with load fluctuations. Also, JP-A-61-73592
The disorder suppression device proposed in the publication requires a special circuit for determining the disorder, the circuit for determining the disorder is difficult to adjust, and the control method for inhibiting the disorder is also complicated. It was The present invention has been made in order to solve various problems in the conventional device as described above,
An object of the present invention is to provide a compressor control device for an air conditioner, which can reliably operate a compressor with high operating efficiency without causing a disturbance.

[0005]

In order to achieve the above object, in a compressor control device for an air conditioner of the present invention, an inverter circuit shifts the compressor in response to a change in output voltage and a change in frequency, and a current detecting means. Detects the output current of the inverter circuit, the power detection means detects the output power of the inverter circuit, and the rotation speed detection means detects the rotation speed of the compressor, thereby detecting the driving state of the compressor to be controlled. It is a composition. Further, in the compressor control device for an air conditioner of the present invention, the rotation speed of the compressor to be controlled is converged to the command rotation speed by the output frequency change of the inverter circuit by the frequency control means, and the minimization control means is: The output voltage of the inverter circuit is changed by a predetermined amount every predetermined period, and the current detected by the current detection unit or the power detection unit detects it according to the amount of change in the output power detected by the power detection unit at that time. Output power is minimized.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A compressor control device for an air conditioner according to the present invention detects an inverter circuit that drives a compressor of an air conditioner at a variable speed by an output voltage change and a frequency change, and an output current of the inverter circuit. Current detection means, power detection means for detecting the output power of the inverter circuit, rotation speed detection means for detecting the rotation speed of the compressor, and rotation of the compressor by changing the output frequency of the inverter circuit. Frequency control means for controlling the number to converge to the command rotation speed,
The output voltage of the inverter circuit is changed by a predetermined amount every predetermined period, and the current or the power detected by the current detection unit is changed according to the amount of change in the output power detected by the power detection unit at that time. And a minimization control means for minimizing any value of the output power detected by the detection means.

With the above structure, the compressor control device for an air conditioner of the present invention controls the output voltage of the inverter circuit while controlling the rotation speed of the compressor to a predetermined target value by the frequency control means. The value of either the output power or the current can be minimized according to the variation or absolute value of the output power at that time. Therefore, the compressor can be driven with high operation efficiency.

In the compressor control device for an air conditioner of the present invention, the minimization control means is detected by the current detection means in accordance with the absolute value of the output power detected by the power detection means. The output voltage of the inverter circuit is changed by a predetermined amount every predetermined period so as to minimize the value of either the current or the output power detected by the power detection means. Therefore, the drive control of the compressor can be performed with high operation efficiency.

Also, in the compressor control device for an air conditioner of the present invention, the minimization control means determines the number of rotations detected by the rotation speed detection means and the output frequency output from the frequency control means, An optimum slip amount storage that has a slip amount calculation means for obtaining the slip amount of the compressor, and stores the rotation speed and the slip amount of the compressor when the output power or current is minimized by the minimization control means. Means are provided, the minimization control means, at the start of the minimization process, the optimum slip amount and the current slip amount with respect to the current rotation speed of the compressor stored by the optimum slip amount storage means. And means for determining the increasing / decreasing direction of the output voltage of the inverter circuit in the minimization process according to the difference. With this configuration, the compressor control device for an air conditioner of the present invention can control the compressor to be controlled to the optimum state in a short time.

Further, the compressor control device for an air conditioner according to the present invention further comprises pressure detection means for detecting the discharge pressure of the compressor, and the rotation speed detection means is detected by the pressure detection means. It has means for judging the maximum frequency component in the pressure pulsation as the rotational speed. Therefore, the rotation speed of the compressor can be reliably detected.

Further, the compressor control device for an air conditioner according to the present invention detects a disordered state of the compressor based on the discharge pressure of the compressor, and in the case of a disordered state, a disorderly determination signal is sent to the minimization control means. When the minimization control means receives the turbulence determination signal from the turbulence determination means, the output voltage of the inverter circuit is increased or decreased to avoid the turbulence state of the compressor. Have means. Therefore, in the compressor control device for the air conditioner of the present invention, the turbulent state of the compressor is reliably avoided in the control of the inverter circuit.

Further, in the compressor control device for an air conditioner of the present invention, the irregularity determining means selects the rotation speed detected by the rotation speed detecting means from among the pressure pulsation detected by the pressure detecting means. It has means for measuring the amount of frequency components other than the components and outputting a disturbance determination signal when the amount is larger than a predetermined amount. Therefore, the disordered state is accurately detected, and the disordered state of the compressor is reliably avoided in the minimization process.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a compressor control device for an air conditioner according to the present invention will be described below with reference to the drawings. First, the control principle of the compressor control device for an air conditioner of this embodiment will be described. 1 and 2 are graphs showing an example of a variation state of an inverter output current and a variation state of output power with respect to a variation of an inverter output voltage from a set voltage in a general inverter circuit. FIG.
[Fig. 4] is a graph showing each variation state of the inverter output current and output power when the compressor is operated under a constant relatively high load condition. As shown in FIG. 1, there is a point where both the inverter output current and the output power at the changed inverter output voltage from the set voltage become the minimum.

FIG. 2 is a graph showing the inverter output current and output power at a changed inverter output voltage from the set voltage under a constant relatively low load condition. Similar to FIG. 1, there is a point that both the inverter output current and the output power at the changed inverter output voltage from the set voltage become the minimum, but the output power fluctuation rate is considerably smaller than the inverter output current fluctuation rate. ,
It is very difficult to search for the minimum point of fluctuation in output power. Actually, the operating efficiency under the low load condition hardly changes at any point in the variation amount of the inverter output voltage, so that the effect of setting the variation amount of the voltage to the optimization is small.

However, since the fluctuation amount of the inverter output current under the low load condition is relatively larger than the fluctuation amount of the output power, the minimum point of the fluctuation amount of the inverter output current can be easily searched. Minimizing the output power under the constant rotation speed of the compressor corresponds to maximizing the operating efficiency, that is, performing the same work with the minimum output power. For this reason, minimizing the output power maximizes operating efficiency. On the other hand, minimizing the inverter output current is equivalent to minimizing the exciting current of the compressor, and therefore minimizing the load on the drive element of the inverter device and improving the operating efficiency. Become. In the compressor control device of the present invention,
Detects the amount of output power fluctuation in the inverter circuit,
Depending on the amount of fluctuation, it is switched between power minimization processing and current minimization processing. That is, when the variation of the output power is less than the predetermined value, the inverter output current is minimized, and when the variation of the output power exceeds the predetermined value, the output power is minimized. . By performing the minimization process as described above,
The compressor control device for an air conditioner of the present invention realizes control with high operation efficiency.

FIG. 3 is a system configuration diagram showing a preferred embodiment of a compressor control device for an air conditioner according to the present invention. In the inverter circuit 1 connected to the three-phase power source 2, the three-phase power source 2 is rectified by the rectifying unit 3 and then smoothed by the smoothing capacitor 4 or the like to form a direct current. This DC current is converted into an AC current by the inverter unit 6 and drives the motor of the compressor 7. The discharge pressure of the compressor 7 is detected by the pressure sensor 10, and the pressure signal from the pressure sensor 10 is subjected to frequency analysis by the rotation speed detection means 14 to detect the rotation speed of the compressor 7. The rotation speed detected by the rotation speed detection means 14 is transmitted to the frequency control means 15. The frequency control means 15 controls the frequency formed in the inverter circuit 1 so that the rotation speed of the compressor 7 matches the command frequency f ′ given from the outside.

In the inverter circuit 1, the power detection means 9, for example, a power sensor, detects the output power of the inverter circuit 1 by detecting the voltage across the protective shunt resistor 5 provided in the DC portion of the inverter circuit 1. To do. The output current of the inverter unit 6 is detected by the current detection means 8, for example, a current sensor. The minimization control means 12 controls the adjustment voltage Vc of the inverter circuit 1 so as to minimize the output power detected by the power detection means 9 or the current detected by the current detection means 8. The optimum slip amount storage means 11 calculates and stores the optimum slip amount of the compressor 7 when the output power or current is minimized, and outputs the data to the minimization control means 12. Disturbance determination means 13
Determines a disordered state of the compressor 7 (an unstable state causing abnormal vibration) from the pressure signal of the pressure sensor 10, and outputs a disordered state determination signal to the minimization control means 12 when the compressor 7 is in the disordered state.

Next, the operation of the compressor controller of the air conditioner of the present embodiment constructed as described above will be explained. The frequency control means 15 calculates therein the difference between the drive frequency f for the inverter circuit 1 and the rotation speed r of the compressor 7 detected by the rotation speed detection means 14, that is, the slip amount m. Further, the slip amount m calculated in this way is added to the input command frequency f ′ to obtain a new drive frequency f.
Is calculated and output to the inverter circuit 1. As a result, the rotation speed r of the compressor 7 is controlled to converge to the rotation speed of the command frequency f '. In addition, the power detection unit 9 detects the output power P output from the rectification unit 3 by detecting the voltage across the shunt resistor 5 for protection. The current detection means 8 uses the current I output from the inverter unit 6.
To detect. The minimization control means 12 outputs the output power P detected by the power detection means 9 or the current I detected by the current detection means 8 in a state where the rotation speed r of the compressor 7 is controlled to converge to the command frequency f ′. The regulated voltage Vc for the inverter circuit 1 is controlled in order to minimize

Next, the control method in the minimization control means 12 configured as described above will be described with reference to the flowchart of FIG. FIG. 4 is a flow chart showing a minimization process in the minimization control means 12, and the minimization process is executed at a predetermined fixed cycle, for example, every one second. First, in step S1, the minimization control means 12 determines whether or not the current operating state of the compressor 7 is a disordered state, that is, a state in which low-cycle vibration is generated, based on the output signal of the disorderedness determination means 13. To do. If the compressor 7 is in the disordered state, in step S20, the output voltage Vt + 1 at the next time of the inverter circuit 1 is returned to the output voltage Vt-1 at the previous time when the disorder was not generated, and the compressor concerned. This flow is terminated while avoiding the disordered state of 7. The reason why such a flow is set is that the output voltage V that causes the turbulent state of the compressor 7 is generated.
The range of t is limited and is based on the fact that it is a very narrow range. By manipulating the output voltage Vt in this manner, the turbulent state of the compressor 7 can be easily avoided.

In step S1, if the compressor 7 is not in the disordered state, the current output power Pt is input in step S2, and the current output power Pt and the output power Pt-1 at the previous time are input in step S3. The difference of the predetermined value Po
It is determined whether it is greater than. In step S3, when the change in the output power Pt is large, the output power Pt
Is minimized. On the contrary, when the change in the output power Pt is small, the current minimization control is performed.
If the change in the output power Pt is large in step S3, the increase / decrease state of the output power Pt is checked in step S4. If the current output power Pt is increasing, the increase / decrease state of the output voltage Vt is checked in step S5. When it is determined in step S5 that the output power Pt is increasing due to the increase in the output voltage Vt, the operating efficiency is deteriorating. Therefore, in step S6, the output voltage Vt + 1 at the next time is increased by a predetermined amount ΔV. Then, the flow ends. If it is determined in step S5 that the output power Pt has increased due to the decrease in the output voltage Vt, it means that the operating efficiency is improved. Therefore, in step S7, the output voltage Vt + 1 at the next time is set to the predetermined amount Δ.
Add only V.

On the other hand, if it is determined in step S4 that the current output power Pt has decreased compared to the output power Pt-1 at the previous time, the output voltage Vt in step S8.
The increase / decrease state of is investigated. If it is determined in step S8 that the output power Pt has decreased due to the increase in the output voltage Vt, it means that the operating efficiency is improved. Therefore, in step S9, the output voltage Vt + 1 at the next time is set to the predetermined amount ΔV.
Just add and end this flow. When it is determined in step S8 that the output power Pt has decreased due to the decrease in the output voltage Vt, the output voltage Vt + 1 at the next time is decreased by the predetermined amount ΔV in step S10, and this flow ends. As described above, by controlling the output voltage Vt in the direction in which the output power Pt decreases, the output power Pt can be converged to the minimum point. When it is determined in step S3 that the variation amount of the output power Pt is smaller than the predetermined value Po, the current current It is input from the current detection means 8 in step S11, and the current current It and the previous time are input in step S12. The magnitude relationship between the difference in the current It-1 and the predetermined value Io is examined. Step S1
In 2, when the variation amount of the current It is larger than the predetermined value Io, the current minimization control is performed. On the other hand, in step S12, when the variation amount of the current It is smaller than the predetermined value Io, it is determined that the minimization process has been completed, and this flow ends.

When it is determined in step S12 that the variation amount of the current It has increased or decreased beyond the predetermined value Io, the current minimization control is performed as follows. First, the increase / decrease state of the current It is determined in step S13, and if the current It is increasing, step S1
At 4, the increase / decrease state of the output voltage Vt is checked. If it is determined in step S14 that the current has increased due to the increase in the output voltage Vt, it means that the operating efficiency is deteriorated. Therefore, in step S15, the output voltage V at the next time is increased.
t + 1 is reduced by a predetermined amount ΔV. Conversely, step S1
If it is determined in 4 that the output voltage Vt has increased due to the decrease, it means that the operating efficiency is improved, so in step S16, the voltage Vt + 1 at the next time is added by a predetermined amount ΔV. On the other hand, if it is determined in step S13 that the current It is decreasing, the increase / decrease state of the output voltage Vt is checked in step S17.
When it is determined in step S17 that the current has decreased due to the increase in the output voltage Vt, the operation efficiency is improved, so in step S18, the output voltage Vt + 1 at the next time is increased by the predetermined amount ΔV. Conversely, step S
When it is determined in 17 that the current has decreased due to the decrease of the output voltage Vt, the operating efficiency is improved, so in step S19, the output voltage Vt + 1 at the next time is reduced by a predetermined amount ΔV, and this flow is executed. Ends.

As described above, step S11 of this embodiment.
In the subsequent minimization process, the output voltage V
By controlling t, the current is converged to the point where it becomes the minimum. In this embodiment, the current minimization or the power minimization is switched depending on the magnitude of the variation in the output power, but the switching may be performed by comparing the absolute value of the output power with a predetermined value. For example, when the output power is less than or equal to the predetermined value, it is determined that the load is low, and the current minimization process is performed as described above. Conversely, when the output power is at or above the predetermined value, the above is performed. Power minimization process. By performing such a minimization process, the same effect as in the case of the above-described embodiment in which control is performed according to the amount of change in output power can be obtained.

Next, the minimization control means 12 of the above-mentioned embodiment.
The control method at the time of starting the control will be described with reference to the flowchart of FIG. The process shown in the flowchart of FIG. 5 is started by the minimization control means 12 several seconds after the rotation speed of the compressor 7 is stabilized. In step S100 when the control is started, the rotation speed r of the compressor 7 and the drive frequency f of the frequency control means 15 are input to the minimization control means 12 having a slip amount calculating means. In step S101, the slip amount m is obtained by subtracting the rotation speed r from the drive frequency f. In step S102, the optimum slip amount m ′ for the current drive frequency f stored in the optimum slip amount storage means 11 is input. In step S103, the current slip amount m and the optimum slip amount m ′ are compared to determine the current slip amount m.
Is larger than the optimum slip amount m ', step S1
At 04, the output voltage Vt + 1 at the next time is decreased by a predetermined amount ΔV to bring the current slip amount m close to the optimum slip amount m ′. On the other hand, when it is determined in step S103 that the current slip amount m is smaller than the optimum slip amount m ′, the output voltage Vt + 1 at the next time is increased by a predetermined amount ΔV to optimize the current slip amount m. Move closer to the slip amount m '.
As described above, at the start of control of the minimization control process,
Since the increasing / decreasing direction of the output voltage Vt can be set correctly, quick convergence control is possible.

[0025]

[Table 1]

Table 1 is an example of information on the optimum slip amount stored in the optimum slip amount storage means 11. The optimum slip amount m'is set by setting the optimum slip amount for each frequency at constant frequency intervals, and this information is used by the minimization control means 1.
The amount of slip when the control completion signal 2 is output is stored.

Next, a detection method of the rotation speed detection means 14 of the compressor control device in this embodiment will be described with reference to the drawings. FIG. 6 is a waveform diagram showing an example of the output signal of the pressure sensor 10 when the compressor 7 is operating at a rotation speed of 48 Hz. As shown in the waveform diagram of FIG. 6, the pressure pulsation of this signal has the same frequency component as the rotation speed of the compressor 7.
It is possible to detect the rotation speed of. FIG. 7 is a block diagram of the rotation speed detection means 14 in this embodiment. The pressure signal U (t) from the pressure sensor 10 is input to a plurality of filters 16a to 16n having different frequency characteristics. FIG. 8 is a characteristic diagram showing an example of frequency characteristics in each of the filters 16a to 16n. Each filter 16a
16n have frequency characteristics as shown in FIG.
When (t) is an input signal and y (t) is an output signal, the output signals y (t) of the filters 16a to 16n are obtained by the following calculation.

Y (t) = a0 · y (t-1) + a1 · y (t-2) + b1 ·
U (t-1) + b2 ・ U (t-2)

In this equation, t is the current time,
t-1 indicates the previous time and t-2 indicates the previous time. Further, a0, a1, b1 and b2 are filter coefficients, which are determined by the value of the passing frequency. Therefore, the filters 16a to 16n have a property of passing only a signal of a certain frequency component and blocking the other frequency components. Further, each of the plurality of filters 16a to 16n is set to have an amplitude peak at different frequencies. Therefore, each of the filters 16a-16
By looking at the distribution of the amplitude of the output signal y (t) at n, it can be detected which frequency component the pressure signal U (t), which is the input signal, has. As shown in FIG. 7, the maximum value determination means 17 to which the output signals y (t) from the filters 16a to 16n are input detects the maximum value of the amplitudes of the output signals of the filters 16a to 16n. Input signal U
The maximum frequency of (t) can be determined. As a result,
The maximum frequency component in the pressure signal U (t) from the pressure sensor 10 is detected, and the rotation speed of the compressor 7 is reliably detected.

Next, the pressure signal U from the pressure sensor 10
The operating principle of the disturbance determination means 13 for determining the disturbance state of the compressor 7 based on (t) will be described. FIG. 9 shows the pressure sensor 1 when a disordered state occurs in the compressor 7.
The waveform diagram of the pressure signal U (t) which is an output signal of 0 is shown, and is an example of the waveform diagram when the actual rotation of the compressor 7 is 35 Hz. As shown in the waveform diagram of FIG.
In addition to the actual rotation frequency of 35 Hz, another frequency, for example, a frequency component having a cycle of about 3 times is generated. In such a turbulent state, there are many components other than the frequency component of the actual rotation speed. Therefore, by recognizing the presence of such a component, it is possible to determine whether or not the compressor 7 is in the turbulent state. Is.

FIG. 10 is a block diagram showing the irregularity judging means 13. In FIG. 10, the filter 18
Is a filter having a frequency characteristic similar to the frequency characteristic shown in FIG. 8 described above and passing only a specific frequency component. This passing frequency is set to the value of the rotation speed r of the compressor 7 detected by the rotation speed detection means 14 described above. The filter 18 of the disorder determining unit 13 shown in FIG. 10 outputs the passing signal z (t) and the cutoff signal e (t). The passing signal z (t) is a signal that passes through the filter 18 with respect to the input signal V (t), and the cutoff signal e (t) is a signal that is cut off by the filter 18. This interruption signal e
(t) is obtained by subtracting the passing signal z (t) from the input signal V (t) and is expressed as follows.

E (t) = V (t) -z (t)

In the irregularity judging means 13, the comparing means 19
Compares the amplitudes of the passing signal z (t) and the cutoff signal e (t). When the amplitude of the cutoff signal e (t) is larger than the predetermined ratio with respect to the passing signal z (t), the comparison means 19 determines that the compressor 7 is in disorder and outputs a disorder determination signal.
On the contrary, when the amplitude of the cutoff signal e (t) is smaller than the predetermined ratio with respect to the passing signal z (t), the comparison means 19 causes the compressor 7
Is not in the disordered state and does not output the disorderly determination signal. Each unit such as the minimization control unit 12 in the compressor control device for an air conditioner of the present invention can be realized by using a dedicated hardware circuit, or can be realized by software using a computer. it can.
Further, in the above-described embodiment, even if the input power source of the inverter circuit 1 is a power source other than the three-phase power source, for example, a single-phase power source, the same effect as that of the above-described embodiment is obtained.

[0034]

As described above, since the compressor control device for an air conditioner of the present invention is provided with the minimization control means to minimize the electric power and the electric current, the compressor to be controlled is controlled. Drive control can be performed with high operating efficiency with a small amount of power and current.

Further, the compressor control device for the air conditioner of the present invention is provided with the optimum slip amount storage means for storing the number of revolutions and the slip amount of the compressor when the electric power or current becomes the minimum. Since the output voltage increasing / decreasing direction of the inverter circuit at the start of control in the minimization process can be set correctly, the compressor to be controlled can be controlled to the optimum state in a short time.

Further, in the compressor control device for an air conditioner of the present invention, the rotation speed detecting means is configured to detect the rotation speed of the compressor to be controlled from the pressure detected by the pressure detecting means. Accurate control is possible by reliably detecting the number of revolutions of.

Further, by providing the disorder condition judging means, the disorder condition of the compressor can be accurately detected, and the disorder condition of the compressor can be surely avoided during the control.

[Brief description of drawings]

FIG. 1 is a characteristic diagram of an inverter output current and an output power with respect to a change in an inverter output voltage at a high load in a general inverter device.

FIG. 2 is a characteristic diagram of inverter output current and output power with respect to changes in the inverter output voltage when the load is low in a general inverter device.

FIG. 3 is a block diagram of a preferred embodiment of a compressor control device for an air conditioner according to the present invention.

FIG. 4 is a flow chart in the minimization control means of the compressor control device for an air conditioner according to the present invention.

FIG. 5 is a flowchart at the start of control in the minimization control means of the compressor control device for an air conditioner according to the present invention.

FIG. 6 is a waveform diagram showing an example of an output signal of a pressure sensor used in the compressor control device for an air conditioner according to the present invention.

FIG. 7 is a block diagram of rotation speed detection means of the compressor control device for the air conditioner according to the present invention.

FIG. 8 is a graph showing an example of frequency characteristics of the filter of the rotation speed detection means of the compressor control device for an air conditioner according to the present invention.

FIG. 9 is a waveform diagram showing an example of an output signal when a disordered state of a pressure sensor used in the compressor control device for an air conditioner according to the present invention is detected.

FIG. 10 is a block diagram of a disturbance regulation unit of a compressor control device for an air conditioner according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inverter circuit 7 Compressor 8 Current detection means 9 Electric power detection means 11 Optimal slip amount storage means 12 Minimization control means 13 Disturbance determination means 14 Rotation speed detection means 15 Frequency control means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiteru Ito 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Tsuneoka Yoshioka, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Hideo Ogata 4-2-5 Takaidahondori, Higashiosaka-shi, Osaka, Matsushita Refrigerating Machinery Co., Ltd. (72) Inventor ▲ Yoshi ▼ Izumi 4-2 Takaida-hondori, Higashiosaka, Osaka No. Matsushita Refrigerator Co., Ltd. (72) Inventor Shusaku Watanabe 4-5 Takaidahondori, Higashi-Osaka City, Osaka Prefecture Matsushita Refrigerator Co., Ltd.

Claims (6)

[Claims] 1. An inverter circuit that shift-drives a compressor of an air conditioner according to a change in output voltage and a frequency, a current detection unit that detects an output current of the inverter circuit, and a power that detects an output power of the inverter circuit. A detection means, a rotation speed detection means for detecting the rotation speed of the compressor, a frequency control means for changing the output frequency of the inverter circuit to converge the rotation speed of the compressor to a command rotation speed, The output voltage of the inverter circuit is changed by a predetermined amount every predetermined period, and the current detected by the current detection unit or the power detection is performed according to the amount of change in the output power detected by the power detection unit at that time. A minimization control means for minimizing any value of the output power detected by the means, and a compressor for an air conditioner, Control device. 2. The minimization control means controls the current detected by the current detection means or the output power detected by the power detection means in accordance with the absolute value of the output power detected by the power detection means. The compressor control device for an air conditioner according to claim 1, wherein the output voltage of the inverter circuit is changed by a predetermined amount every predetermined period so as to minimize any one of the values. 3. The slippage amount calculation means for obtaining the slippage amount of the compressor based on the rotation speed detected by the rotation speed detection means and the output frequency output from the frequency control means. Having the optimum slip amount storage means for storing the rotation speed and the slip amount of the compressor when the output power or the current is minimized by the minimization control means, and the minimization control means is provided. , At the start of the minimization process,
A comparison is made between the optimum slip amount and the current slip amount with respect to the current rotational speed of the compressor stored by the optimum slip amount storage means, and the output voltage increase / decrease direction of the inverter circuit in the minimization process according to the difference. The compressor control device for an air conditioner according to claim 1, further comprising means for determining. 4. The pressure detecting means for detecting the discharge pressure of the compressor is further provided, and the maximum frequency component in the pressure pulsation detected by the pressure detecting means by the rotation speed detecting means is defined as the rotation speed. The compressor control device for an air conditioner according to claim 1, further comprising a determining unit. 5. A turbulence determination means for detecting a turbulence state of the compressor based on the discharge pressure of the compressor and outputting a turbulence determination signal to the minimization control means in the case of the turbulence state,
The air according to claim 1, further comprising means for increasing or decreasing an output voltage of the inverter circuit to avoid a turbulent state of the compressor when the minimization control means receives a turbulence determination signal from the turbulence determination means. Compressor control device for the harmony machine. 6. The irregularity determining means measures the amount of frequency components other than the rotational speed component detected by the rotational speed detecting means from the pulsation of the pressure detected by the pressure detecting means, and the amount thereof is measured. 6. The compressor control device for an air conditioner according to claim 5, further comprising means for outputting a disturbance determination signal when is larger than a predetermined amount.