JPH10174488A - Torque control method for compressor, and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the sound and vibration of a compressor, and sharply sup press the drop of the general efficiency of the compressor by controlling the current or voltage given to a motor by means of an inverter, and driving a compressor for a rotary system of air conditioner by means of this motor. SOLUTION: Three-phase AC power to convert a DC power is supplied to a DC motor 2 from an inverter circuit 1. A microcomputer 8 operates processing of the rotational speed and the speed ripple of a motor and performs ripple control, receiving the input of the positional signal of a rotor 2a that a zero- cross comparator 7 detects and outputs the integrated signal from the differential voltage VNM between the stator winding of the motor 2 and the resistor, and a speed command and a speed change command. The microcomputer calculates the amplitude of compensating voltage, and adds it to the average voltage amplitude and outputs it as an inverter voltage, and further, it supplies a switch command to the inverter circuit 1 through a base drive circuit 9. Consequently, the control to maximize the efficiency, keeping it on a vibration level without hindrance, without performing the reduction of the speed change more than necessary can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a torque of a compressor, and more particularly, to a method for controlling a torque of a compressor.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a current or a voltage applied to a motor by an inverter and controlling a generated torque of the motor in driving a compressor by the motor.

[0002]

2. Description of the Related Art Conventionally, rotary compressors have been widely used as inverter-type air conditioners. This rotary type compressor has a small number of parts, is low in cost, and can achieve high efficiency over a wide operating range (rotation speed range).

[0003] As a rotary type compressor,
A one-cylinder structure and a two-cylinder structure are generally used. Among them, the two-cylinder structure is used for the purpose of reducing the compression torque fluctuation causing the speed fluctuation which is a main factor of the vibration by devising the mechanical structure, and reducing the sound and vibration of the outdoor unit of the air conditioner. However, since the two-cylinder compressor has a structure having two one-cylinder rotary compressors, the production cost is high, and the efficiency of the compressed gas leaks to each built-in compressor. There is a problem that it is reduced as compared with a compressor having a one-cylinder structure.

[0004] On the other hand, a compressor having a one-cylinder structure has rotational fluctuations caused by torque fluctuations.
There is a problem that vibration increases. As a method for solving such a problem, as shown in Japanese Patent Publication No. 4-36000, a method for controlling the motor that drives the compressor to eliminate fluctuations in the rotation of the compressor and vibration of the compressor. (Torque control means) has been proposed.

Further, as a torque control method focusing on the periodicity of the compressor load, a method of performing learning control has been proposed as disclosed in Japanese Patent Publication No. 6-48916.

[0006]

[Problems to be solved by the invention]
In the case of adopting the method disclosed in Japanese Patent Application Laid-Open No. 6000, the motor is controlled so that the speed fluctuation of the compressor approaches zero, so that the peak value of the motor current becomes large and the efficiency of the motor section is reduced. In particular, the drop in efficiency becomes large in a low-speed range where there is no speed fluctuation suppression effect due to inertial force, and as shown in FIG. 20, the overall compressor efficiency (= compressor mechanism efficiency × motor efficiency) decreases. become.

When the system disclosed in Japanese Patent Publication No. 6-48916 is adopted, a high gain is obtained for all frequency components of the compressor load, and a motor torque corresponding to a small torque fluctuation of a third-order component or more is generated. Therefore, the motor current increases, and it is extremely difficult to minimize the motor loss.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in view of the above circumstances. An air that can reduce the sound and vibration of a rotary type compressor and can significantly suppress a decrease in overall compressor efficiency. An object of the present invention is to provide a torque control method and a device for a compressor for a harmonic machine.

[0009]

According to a first aspect of the present invention, there is provided a torque control method for an air conditioner compressor, wherein a current or a voltage applied to a motor is controlled by an inverter, and the rotary type air conditioner compressor is controlled by the motor. A method for driving a motor, wherein a current or voltage applied to a motor is controlled so that a decrease in efficiency is suppressed to a predetermined value or less, and fluctuations in rotation speed during one revolution of a main shaft of the compressor do not cause practical problems in sound and vibration. This is a method of controlling so as to fall within a range of a value as large as possible.

According to a second aspect of the present invention, there is provided a method for controlling a current or a voltage applied to a motor such that a decrease in efficiency is minimized. According to a third aspect of the invention, there is provided a torque control method for a compressor, which employs a one-cylinder compressor as the compressor. A torque control device for a compressor according to claim 4, wherein the current or voltage applied to the motor is controlled by an inverter, and the motor is used to drive a compressor for a rotary air conditioner. In order to suppress the decrease in efficiency to a predetermined value or less,
In addition, a torque control means for controlling the rotation speed fluctuation during one revolution of the main shaft of the compressor to be as large as possible within a range where sound and vibration do not cause a practical problem is included.

According to a fifth aspect of the present invention, there is provided a torque control device for a compressor, as a torque control means, a proportional / integral operation means for performing a proportional / integral operation by inputting a deviation between a detected speed and a speed command;
Compensation model calculation means for calculating a compensation amount corresponding to the deviation of the detected speed and the speed command based on a model representing a predetermined harmonic component of the compression torque, And an adder for adding the output from the compensation model calculator and outputting a voltage command.

According to a sixth aspect of the present invention, there is provided a torque control device for a compressor, as a torque control means, which attenuates or holds a compensation amount calculated and output by a compensation model calculation means in response to a predetermined speed fluctuation. , Which further includes a switching signal calculating means functioning to keep the speed at a predetermined level. According to a seventh aspect of the present invention, there is provided a torque control device for a compressor, wherein compensation model calculation means is provided for two harmonic components of the compression torque.

According to a eighth aspect of the present invention, there is provided a torque control device for a compressor, wherein a compensation model calculating means is provided for one harmonic component of the compression torque. The torque control device for a compressor according to claim 9 employs a one-cylinder compressor as the compressor.

[0014]

According to the first aspect of the present invention, there is provided a method for controlling torque of a compressor.
An inverter controls a current or a voltage applied to a motor. When the compressor is driven by the motor, the current or the voltage applied to the motor is controlled so that a decrease in efficiency is suppressed to a predetermined value or less. The motor speed is controlled so that the rotation speed fluctuation is within the range of the largest possible value within the range where sound and vibration do not pose a practical problem, so that the peak value of the motor current increases and the motor efficiency decreases. Inconvenience can be suppressed,
In addition, the sound and vibration of the compressor can be kept within a range that does not pose a problem in practical use. As a result, the overall efficiency of the compressor is increased over a wide operating range from low speed to high speed, and the energy saving effect of the air conditioner is greatly improved. Can be done.

According to the compressor torque control method of the second aspect, the current or voltage applied to the motor is controlled so that the reduction in efficiency is minimized. Can be maximized. According to the torque control method for a compressor of claim 3, since a one-cylinder compressor is employed as the compressor for the air conditioner, it is caused by torque fluctuation as compared with the case of employing a two-cylinder compressor. However, the efficiency of the motor can be improved, and the efficiency of the motor can be reduced by adopting the torque control method of claim 1 or 2. In addition, the noise and vibration of the one-cylinder compressor can be kept within a range that does not pose a practical problem, thereby increasing the overall efficiency of the compressor over a wide operating range from low speed to high speed, and consequently energy saving of the air conditioner. The effect can be greatly improved.

According to the fourth aspect of the present invention, the current or voltage applied to the motor is controlled by the inverter, and when the compressor for the rotary air conditioner is driven by the motor, the torque control means is used. The current or voltage applied to the motor is reduced as much as possible within a range where fluctuations in rotation speed during one revolution of the main shaft of the compressor do not cause sound and vibration problems in practical use. Since the control is performed so as to be within the range of the values, the disadvantage that the peak value of the motor current becomes large and the efficiency of the motor is reduced can be suppressed, and the sound and vibration of the compressor can be practically reduced. This can increase the overall efficiency of the compressor over a wide operating range from low speed to high speed, and consequently the air conditioner. The energy effect can be greatly improved.

According to a fifth aspect of the present invention, the torque control means includes a proportional / integral calculating means for performing a proportional / integral calculation by using a deviation between the detected speed and the speed command as an input; Compensation model calculation means for calculating a compensation amount corresponding to a predetermined harmonic component of the compression torque based on a model representing a predetermined harmonic component of the compression torque with a deviation from the command as input, and output from the proportional / integration calculation means and compensation model calculation means And an adding means for adding the output from the control unit and outputting a voltage command, so that the same operation as that of claim 4 can be achieved.

In the torque control device for a compressor according to claim 6, as the torque control means, the compensation amount calculated and output from the compensation model calculation means in response to reaching the predetermined speed fluctuation, or Since the apparatus further includes a switching signal calculating means that functions to hold and maintain the predetermined speed fluctuation, in addition to the effect of claim 5, it is possible to maintain the predetermined speed fluctuation.

According to the torque control device for a compressor of claim 7, since the compensation model calculating means is provided for two harmonic components of the compression torque, the compensation accuracy can be improved. The same operation as the sixth aspect can be achieved. According to the torque control device for a compressor of claim 8, since the compensation model calculation means is provided for one harmonic component of the compression torque, the compensation model calculation means can be simplified. The same operation as that of No. 6 can be achieved.

In the torque control device for a compressor according to the ninth aspect, a one-cylinder compressor is employed as the compressor. Although the induced rotational fluctuation increases, and the sound and vibration increase, the efficiency can be increased. By adopting the torque control device according to claim 4 or 5, the motor efficiency decreases. And the sound and vibration of the one-cylinder compressor can be kept within a range that does not pose a practical problem. As a result, the overall efficiency of the compressor can be increased over a wide operating range from low speed to high speed, and as a result, the air conditioner The energy saving effect can be greatly improved.

This will be described in more detail. A rotary air conditioner compressor as an example of a compressor is usually supported by an elastic body (for example, rubber or the like) as shown in FIG. Is connected to the heat exchanger by means of a refrigerant pipe having a shape having a shape, a considerable part of the vibration is absorbed by the elastic body and the refrigerant pipe. And
As is apparent from FIG. 19 showing the change characteristic of the excitation force of the outer plate of the outdoor unit with respect to the rotation speed when the speed fluctuation caused by the compression torque fluctuation is changed, even if the speed fluctuation is not asymptotically reduced to zero, It can be seen that the excitation force of the outer panel of the outdoor unit can be sufficiently reduced.

The present invention has been made based on the above findings. A value as large as possible within a range where sound and vibration do not cause a practical problem can be determined empirically, for example, in accordance with the installation environment of the outdoor unit.

[0023]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an electric circuit diagram showing an embodiment of a compressor drive control device to which the torque control method of the present invention is applied, FIG. 2 is a diagram showing a control model corresponding to FIG. 1, and FIG. It is a block diagram shown in detail.

This compressor drive control device includes an inverter circuit 1 for converting a DC power supply into a three-phase AC power supply by performing a switching operation based on a switch command given from the outside, and a three-phase AC power output from the inverter circuit 1. A brushless DC motor 2 whose power is supplied to Y-connected stator windings 2u, 2v, 2w, a compressor 3 driven by a rotor 2a of the brushless DC motor 2, and a stator winding 2
u, 2v, 2w
u, 4v, 4w, a differential amplifier 5 for obtaining a difference voltage VNM between the neutral point voltage of the stator windings 2u, 2v, 2w and the neutral point voltage of the resistors 4u, 4v, 4w, and the obtained difference. An integrator 6 that integrates the voltage VNM and outputs an integration signal ∫VNMdt;
Detecting the zero crossing of the integration signal ∫VNMdt, the rotor 2
A zero cross comparator 7 that outputs a position signal indicating the rotational position of a, a speed command, a speed fluctuation command, and a position signal are input to perform necessary processing, and a switch command is supplied to the inverter circuit 1 via the base drive circuit 9. And a microcomputer 8. In addition, the differential amplifier 5, the integrator 6, and the zero-cross comparator 7 constitute a position detector.

As shown in FIG. 2, a control model corresponding to the compressor drive control device shown in FIG.
Subtraction unit 101 for calculating the difference from the rotation speed of C motor 2
And a PI control unit 102 that performs proportional control and integral control using the difference output from the subtraction unit 101 as an input to output a proportional control result and an integral control result, and performs N rotation using the difference output from the subtraction unit 101 as an input. (N is a natural number) a speed fluctuation average value calculation unit 103 that calculates an average size Δω of speed fluctuations, and the average value of the speed fluctuation Δω output from the speed fluctuation average value calculation unit 103 is used as an input. Or 1
, A multiplication unit 105 that multiplies the rotation speed of the brushless DC motor 2 by the output from the switching unit 104 to output a multiplication result, and a multiplication result output from the multiplication unit 105 as an input. A variable structure first-order component compensator 106 that performs next-order component compensation and outputs a compensation value;
The adder 107 outputs the voltage command by adding the proportional control result, the integration control result, and the compensation value, the amplifier 107 ′ that receives the voltage command output from the adder 107 as input, and the amplifier 107 ′. A subtracting unit 108 that calculates and outputs a difference between the output voltage to be output and a portion Eτ− related to generation of a torque component current among the motor speed electromotive voltage;
A voltage / current transfer function (first-order lag element determined by the resistance and inductance of the motor winding) 109 of a motor that outputs a current with the difference output from the subtraction unit 108 as an input,
The current output from the voltage / current transfer function 109 of the motor and the current iτ- equivalently representing a torque error component caused by not directly controlling the current waveform (phase / amplitude) according to the rotor position. Subtraction unit 110 that calculates and outputs the difference
And a current / torque transfer function 111 of a motor that outputs a motor torque using the difference output from the subtractor 110 as an input.
And a subtractor 112 for subtracting the motor torque and the compressor load torque output from the motor current / torque transfer function 111 to output a compressor shaft torque; and a compressor shaft torque output from the subtractor 112 as an input. , And a torque / speed transfer function 113 of the motor that outputs the speed.
The subtraction unit 108, the voltage / current transfer function 109, the subtraction unit 110, the current / torque transfer function 111, the subtraction unit 112
And the torque / speed transfer function 113 constitute the brushless DC motor 2.

As shown in FIG. 3, the microcomputer 8 includes a period measuring timer 8 for stopping, resetting and restarting by interrupt processing 1 upon receiving a position signal.
1, a position signal period calculator 82 that calculates the position signal period using the timer value when the period measurement timer 81 stops as an input, and a speed that uses the position signal period output from the position signal period calculator 82 as an input. A speed calculating unit 83 that calculates and outputs a current speed and calculates a difference between a speed command given from the outside and a current speed output from the speed calculating unit 83 and outputs a deviation as a speed fluctuation. A calculation unit 84, a switching signal calculation unit 85 that calculates and outputs a switching signal with the speed fluctuation output from the deviation calculation unit 84 and a speed fluctuation command given from the outside as inputs,
A primary component compensation model computing unit 86 that computes and outputs a primary component compensation model with the speed fluctuation output from the deviation computing unit 84 and the switching signal output from the switching signal computing unit 85 as inputs, and a deviation computing unit 84 A PI calculation unit 87 that performs a PI calculation using the speed fluctuation output from the unit as an input and outputs a calculation result, and a primary component compensation model and a PI calculation unit 87 output from a primary component compensation model calculation unit 86
And an adder 88 that outputs the result as a voltage command, and calculates a timer value by inputting the cycle of the position signal output from the position signal cycle calculator 82 and a phase amount command given from the outside. Value calculation unit 89 for outputting the timer signal, and the timer value output from the timer value calculation unit 89 are set, started by the interrupt processing 1 by receiving the position signal, and the set timer value is counted. And a timer value output from a timer value calculation unit 89 is set.
The power-on control timer 91 outputs a count-over signal when the set timer value is counted, and the count-over signal is output from the phase correction timer 90. An inverter mode selection unit 9 for reading and outputting a voltage pattern from the memory 93 by interrupt processing 2 by a signal or interrupt processing 3 by a count-over signal output from a conduction width control timer 91
2, and a PWM unit 94 that performs pulse width modulation using a voltage command output from the adder 88 and a voltage pattern output from the inverter mode selection unit 92 as inputs, and outputs a switch signal.

The first-order component compensation model calculation section 86 has
Compensation is performed in which the gains other than the next component are 0. Therefore, there is no problem even if the speed fluctuation is used as an input to the primary component compensation model calculation unit 86. That is, the speed command is constant (DC) in a steady state.
The next component compensation model calculation unit 86 receives a direct current (or a signal having a frequency different from the output signal of the signal model)
Its output is zero. In other words, even if the speed fluctuation (= motor speed-speed command) is used as an input to the primary component compensation model calculation unit 86, the output of the primary component compensation model calculation unit 86 is determined only by the motor speed. Therefore, the control performance is not affected.

FIGS. 4 to 6 are flowcharts for explaining the processing of the microcomputer 8. FIG. 4 shows the interrupt processing 1
FIG. 5 illustrates the interrupt process 2 and FIG. 6 illustrates the interrupt process 3. The processing of the flowchart in FIG.
This is performed every time a position signal is received. Step SP
In step SP1, the value of the phase correction timer 90 is calculated from the phase amount command.
Is set in step SP3. In step SP3, the phase correction timer 90 is started.
In step SP4, the period measurement timer 81 is stopped. In step SP5, the value of the period measurement timer 81 is read. In step SP6, the value of the period measurement timer 81 is reset, and the period measurement timer 8 is reset for the next period measurement.
Start one. In step SP7, the cycle of the position signal is calculated. In step SP8, the motor rotation speed is calculated from the calculation result of the cycle of the position signal. In step SP9, the speed fluctuation is calculated based on the motor rotation speed and the speed command. And step SP1
0, PI control is performed on the speed fluctuation, an average voltage amplitude command is calculated, and in step SP11, an average value of the magnitude of the speed fluctuation is calculated, and a switching signal is output based on the obtained average value. In step SP12,
Compensation voltage amplitude is calculated based on the speed fluctuation and the switching signal, and in step SP13, the compensation voltage amplitude is added to the average voltage amplitude, and this is output as an inverter voltage, and the process returns to the original processing.

The process of the flowchart of FIG. 5 is performed every time the count over signal is output from the phase correction timer 90. In step SP1, the inverter mode is advanced by one step, and in step SP2, a voltage pattern corresponding to the advanced inverter mode is output,
In step SP3, the timer value of the conduction width control timer is calculated from the conduction width command, and in step SP4, the timer value ｛= (conduction angle−120) de is supplied to the conduction width control timer.
The timer value 分 の for g is set, and in step SP5, the energization width control timer is started, and the process returns to the original processing.

The process of the flowchart of FIG. 6 is performed every time the count-over signal is output from the power supply width control timer 91. In step SP1, the inverter mode is advanced by one step. In step SP2, a voltage pattern corresponding to the advanced inverter mode is output, and the process returns to the original processing.

FIG. 7 is a diagram showing signal waveforms at various parts of the compressor drive control device shown in FIGS. Brushless D
When the compressor 3 is driven by the C motor 2, FIG.
The difference voltage VNM is obtained as shown in FIG. 7A, the integration signal ∫VNMdt is obtained as shown in FIG. 7B, and the position signal is obtained as shown in FIG.

The phase correction timer 90 is started as shown in FIG. 7D by the interrupt processing 1 based on the position signal (see the starting point of the arrow shown in FIG. 7D). Then, every time a count over signal is output from the phase correction timer 90 {see the end point of the arrow shown in FIG. 7D}, the energization width control timer 91 starts as shown in FIG. 7E. {See the starting point of the arrow shown in FIG. 7 (E)}.

A count-over signal is output from the phase correction timer 90 {see the end point of the arrow shown in FIG. 7D}, and a count-over signal is output from the conduction width control timer 91 {FIG. The inverter mode is advanced by one step as shown in (M) of FIG. 7 for each｝ with reference to the end point of the arrow shown in (E).
As shown in the middle (K), the switching transistors 12u1, 12u2, 12v1, 12v of the inverter circuit 1
The on-off states of 2, 12w1 and 12w2 are switched corresponding to the inverter mode. Also, (L) in FIG.
Each switching transistor is chopper-controlled by the PWM control unit based on the inverter output voltage as shown in FIG. Note that the broken line shown in (L) in FIG.
The output (average voltage) of the calculation unit 87 is shown, and the solid line shown in (L) in FIG. 7 is the output (compensation voltage) of the primary component compensation model calculation unit 86.

Next, the control model of FIG. 2 will be described in more detail. The transfer function Gm (s) of the motor from the torque to the rotation speed is as shown in FIG. 8, and Gm (s) = 1
/ (Jm · s + Dm). Here, J
m is the moment of inertia of the rotating part of the compressor including the motor, Dm
Is the friction coefficient of the rotating part of the compressor including the motor, τm is the motor generated torque, τL is the compressor load torque (compression torque)
Are respectively shown.

Here, as shown in FIG. 9A, the compression torque waveform of the compressor having a one-cylinder structure is a repetitive waveform of one cycle at one rotation angle of the compressor rotating part. Also,
As shown in FIG. 9B, the harmonic component included in the compression torque has a large DC component, a primary component, and a secondary component.
Higher order components attenuate rapidly. Japanese Patent Publication No. 6-489 as a torque control system focusing on the periodicity of the compressor load
A learning control method disclosed in Japanese Patent Publication No. 16 is proposed. In this learning control method, a high gain is provided for all frequency components of the load, and a motor torque corresponding to a small torque fluctuation of a third-order component or more is generated. Accordingly, the motor current increases, and it becomes extremely difficult to minimize the motor loss.

Here, a torque controller capable of independently giving a gain to each frequency component of the compression torque as a disturbance will be considered by applying the principle of an internal model. FIG. 10 shows a speed control configuration of a conventional compressor. According to the internal model principle, the necessary and sufficient condition for controlling the output with respect to the disturbance input {the control output (in this case, the speed) becomes 0} is that the loop transfer function of the control system includes the signal model B (s). It is. This signal model B
(S) is configured such that a predetermined disturbance is obtained as an output with respect to the impulse input.

As shown in FIG. 12, the signal model B (s) for the step disturbance (the DC component of the compressor load torque)
= 1 / s is included in the loop transfer function of the conventional control system of FIG. Therefore, it is understood that the control output based on the average torque of the compressor load, that is, the speed can be set to zero. Here, the primary components included in the compressor load are shown in FIG.
Referring to FIG. 12, it is understood that the conventional control system does not satisfy the output regulation condition based on the internal model principle. Here, the response of the conventional control system to the DC component and the primary component (frequency is 20 Hz) is P
The proportional gain KP and the integral gain KI of the I controller are KP = 1.0 (A · s / rad) and KI = 0.1 (A /
rad), the motor moment of inertia Jm and the friction coefficient Dm are each Jm = 0.001 (Nm · s ² / ra).
d), Dm = 0.0001 (Nm · s / rad), and the torque τm generated by the motor driving power converter is K
FIG. 13 shows a simulation result on the assumption that torque linearization control of T = 1.0 (Nm / A) is realized.
As shown in FIG.

As is apparent from the simulation result of FIG. 13, the speed based on the DC component of the load torque converges to 0 (see FIG. 13A), and the influence is eliminated, but the DC component of the load torque depends on the primary component. Speed fluctuation cannot be suppressed {see (B) in FIG. 13}. FIG. 11 shows a disturbance model for the first-order component added to the open-loop transfer function.
Is a gain for stabilizing the control system and adjusting its response speed.

FIG. 14 shows the DC component of the compressor load torque,
12 shows the results of simulating the response of the control system of FIG. 11 to the next component, respectively. As is clear from the simulation results of FIG. 14, the DC component of the load torque shows a response equivalent to that of the conventional control system of FIG.
4 (see (A)), and the speed fluctuation due to the primary component converges to 0 (see (B) in FIG. 14), so that the influence of disturbance can be eliminated. A similar effect can be obtained by adding a model to a second-order or higher-order disturbance component. FIG.
In the first control system, the stability of the control system and the adjustment of the response time are performed by the proportional element, but may be realized by a combination of other elements (for example, an integral element and a differential element).

However, if the control system shown in FIG.
Because the target value of the movement becomes 0,
Did not solve the problems of the method shown in the report.
No. Therefore, as shown in FIG. 2, the control system shown in FIG.
And a switching unit 104 is added. This switching unit 104
Is the average magnitude of the speed fluctuation during the N rotations of the compressor (average speed)
The output F is set to 0 when Δω falls below a predetermined value,
When the input of the variable structure first-order component compensator 106 is set to 0,
, The signal model (transfer function) B '(s)
B ′ (s) = ω1 / ｛(s
+ Α)^Two+ Ω1^TwoChange to｝. Of course, average speed fluctuation
When Δω is larger than the predetermined value, the switching unit 104
Sets the output F to 1 and inputs the variable structure first-order component compensation unit 106
The force is set to the rotation speed of the motor, and the signal model B '
(S) is calculated as B ′ (s) = ω1 / (s ^Two+ Ω1^TwoChange to)
You. The switching unit 104 also sets the switching frequency
Hysteresis characteristics of appropriate width to prevent
I'm sorry. When the output F = 0, the transfer function B '
The reason for changing (s) to have an attenuation characteristic is that the transfer function
The output of B '(s) is determined by the immediately preceding state quantity (initial value).
Flow signal, for example, when the compressor load torque is low.
If it becomes worse, the amount of compensation of the first-order component becomes high apparently.
To prevent the speed fluctuation from becoming unnecessarily small.
To stop.

FIG. 15 is a diagram showing a simulation result of the operation of the control system of FIG. 15 (A) shows the change over time of the average speed variation Δω, and FIG. 15 (B) shows the change over time of the magnitude of the output of the variable structure primary component compensator 106.
Each is shown. Also, in FIGS. 15A and 15B, a shows a case where the switching unit 104 is provided, and b shows a case where the switching unit 104 is not provided.

As described above, in order to suppress the decrease in motor efficiency due to the torque control, "the periodicity of the compressor load torque and the internal model principle which can easily derive a compensator corresponding to each frequency component, The built controller suitable for minimizing the motor current "and" When the speed fluctuation reaches a predetermined value or less, the input of the compensator corresponding to the primary (or, in addition, the secondary or higher) component is set to 0. Further, the transmission characteristic of the compensator is changed so that each compensator output has an attenuation characteristic during the period, and the speed fluctuation is kept near a predetermined value. " Realize control that does not reduce speed fluctuations (sets speed fluctuations to a predetermined value other than zero), maintains vibration levels that do not hinder practical application as an air conditioner system, and maximizes the efficiency of air conditioners. Can be. In particular, when a one-cylinder compressor is used, the efficiency of the compressor itself can be improved and a sufficient vibration damping effect can be achieved. Also, it goes without saying that a two-cylinder type compressor can be used.

Next, a method of calculating the transfer function B '(s) suitable for microcomputer calculation will be described. Here, for convenience, the interruption point based on the position signal is referred to as a sampling point. Further, the control calculation is performed for each sample point. First, in order to perform digital processing, the model of the primary component shown in FIG.
Discretization is performed by transformation to obtain Equation 1.

[0044]

(Equation 1) Here, T is a control cycle, and in the processing systems of FIGS. 3 to 6, control calculation and output are performed for each output of the position detection circuit.
In the case of a pole motor (inverter output frequency = twice the motor rotation frequency), T = 2π / (12 · ω1).
Therefore, Equation 1 becomes Equation 2.

[0045]

(Equation 2) However, the numerator of Equation 2 includes a product with a non-integer term, and requires sufficient calculation accuracy to eliminate control performance degradation. There is a problem that time becomes long and control becomes difficult.

Therefore, if the operation of the formula 1 is performed every two sample periods and the gain K1 for adjusting the response time of the control is set to K1 / z to simplify the operation expression, the compensation amount u1 (z ) Becomes Equation 3.

[0047]

(Equation 3) The compensation amount u1 (z) between the two samples for which the output of the first-order component compensator is not calculated is estimated from the calculation output result one sample before and three samples before according to Equation 4, and the compensation amount is smoothly output. (See FIG. 16 and Equation 4 was empirically derived).

[0048]

(Equation 4) In addition, when F = 0, the arithmetic expression is represented by Expression 5.

[0049]

(Equation 5) At this time, the constant for determining the speed of the attenuation of the torque compensation amount is a non-integer, and a product-sum operation with this is required. If it is desired to accurately determine the decay speed, there is a problem in calculation. However, there is no problem in controlling the speed fluctuation to be close to the target value even if the calculation accuracy is reduced (the decay time cannot be precisely adjusted). Was.

When the above is modified and arranged, and described by the arithmetic expression of the microcomputer, Equation 6 is obtained. Here, k indicates a sample point.

[0051]

(Equation 6) FIG. 17 shows actual measurement results of the relationship between the target speed fluctuation and the overall compressor efficiency. In this compressor drive system, if the speed fluctuation is set to about 4 to 6 (rpm), both the energy saving effect and the vibration suppression effect can be achieved.

[0052]

According to the first aspect of the present invention, it is possible to suppress the disadvantage that the peak value of the motor current is increased and the efficiency of the motor is reduced, and the sound and vibration of the compressor are practically problematic. Thus, the compressor has a unique effect that the overall efficiency of the compressor can be increased over a wide operating range from low speed to high speed, and the energy saving effect of the air conditioner can be greatly improved.

The invention of claim 2 has a specific effect that the efficiency can be maximized in addition to the effect of claim 1. According to the third aspect of the present invention, the efficiency of the compressor can be increased, the decrease in the efficiency of the motor can be suppressed, and the sound and vibration of the one-cylinder compressor can be kept within a range that does not cause a practical problem. The unique effect is that the overall efficiency of the air conditioner can be increased over a wide operating range from low speed to high speed, and the energy saving effect of the air conditioner can be greatly improved.

According to the present invention, the disadvantage that the peak value of the motor current becomes large and the efficiency of the motor is reduced can be suppressed, and the sound and vibration of the compressor do not cause a practical problem. Accordingly, the compressor has a unique effect that the overall efficiency of the compressor can be increased over a wide operating range from low speed to high speed, and the energy saving effect of the air conditioner can be greatly improved.

The fifth aspect of the invention has the same effect as the fourth aspect. The invention of claim 6 provides the effect of claim 5,
This has a specific effect that a predetermined speed fluctuation can be maintained. According to the seventh aspect of the present invention, the compensation accuracy can be increased, and the same effect as that of the fifth or sixth aspect can be obtained.

According to the eighth aspect of the present invention, the compensation model calculating means can be simplified, and the same effects as those of the fifth or sixth aspect can be obtained. According to the ninth aspect of the present invention, it is possible to increase the efficiency of the compressor, suppress a decrease in the efficiency of the motor, and make the sound and vibration of the one-cylinder compressor within a range that does not cause a practical problem. The unique effect is that the overall efficiency of the air conditioner can be increased over a wide operating range from low speed to high speed, and the energy saving effect of the air conditioner can be greatly improved.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of a compressor drive control device to which a torque control method according to the present invention is applied.

FIG. 2 is a diagram showing a control model corresponding to FIG.

FIG. 3 is a block diagram showing a microcomputer of FIG. 1 in detail.

FIG. 4 is a flowchart illustrating interrupt processing 1;

FIG. 5 is a flowchart illustrating interrupt processing 2;

FIG. 6 is a flowchart illustrating interrupt processing 3;

FIG. 7 is a diagram showing signal waveforms at various parts of the compressor drive control device shown in FIGS. 1 and 4;

FIG. 8 is a diagram illustrating a transfer function of a motor from a torque to a rotation speed.

FIG. 9 is a diagram showing a compression torque waveform and a frequency distribution of the compression torque of the one-cylinder compressor.

FIG. 10 is a block diagram showing a conventional control system.

11 is a block diagram showing a control system in which a first-order component compensator is added to the control system of FIG.

FIG. 12 is a diagram showing waveforms and models of a DC component, a primary component, and a secondary component of a compression torque.

FIG. 13 is a diagram showing a speed response to a disturbance of the control system of FIG. 10;

FIG. 14 is a diagram showing a speed response to a disturbance of the control system of FIG. 11;

FIG. 15 is a diagram illustrating the operation of the control model in FIG. 2;

FIG. 16 is a diagram showing a timing of a compensation amount calculation and a compensation output.

FIG. 17 is a diagram illustrating an example of a relationship between speed fluctuation and overall compressor efficiency.

FIG. 18 is a schematic diagram showing a state where the compressor for an air conditioner is incorporated in an outdoor unit.

FIG. 19 is a diagram illustrating a change in the exciting force of the outdoor unit outer plate with respect to the rotation speed.

FIG. 20 is a diagram showing the relationship between rotational speed fluctuation and overall compressor efficiency when a one-cylinder compressor is driven by conventional torque control.

[Explanation of symbols]

 Reference Signs List 1 inverter circuit 2 brushless DC motor 3 compressor for air conditioner 4 microcomputer

Claims (9)

[Claims] 1. A method of controlling a current or a voltage applied to a motor (2) by an inverter (1) and driving a compressor (3) by the motor (2), wherein the current or the voltage applied to the motor (2) is controlled. The voltage falls within a range in which the reduction in efficiency is suppressed to a predetermined value or less, and a value as large as possible within a range in which fluctuations in rotation speed during one revolution of the main shaft of the compressor (3) do not cause practical problems with sound and vibration. The torque control method for a compressor according to claim 1, wherein the control is performed so as to fall within the range. 2. The method for controlling torque of a compressor according to claim 1, wherein a current or a voltage applied to the motor (2) is controlled so that a decrease in efficiency is minimized. 3. The torque control method for a compressor according to claim 1, wherein the compressor (3) is a one-cylinder compressor (3). 4. An apparatus for controlling a current or a voltage applied to a motor (2) by an inverter (1) and driving a compressor (3) by the motor (2), wherein the current or the voltage applied to the motor (2) is controlled. The voltage is set to a value as large as possible so as to suppress the decrease in the efficiency to a predetermined value or less and so that the rotation speed fluctuation during one revolution of the main shaft of the compressor (3) does not cause sound or vibration in practical use. A torque control device for a compressor, comprising: a torque control means (4) for controlling the inside of the compressor. 5. A torque control means (4) for performing a proportional / integral calculation by using a deviation between a detected speed and a speed command as an input, and a deviation between the detected speed and the speed command. A compensation model computing means (86) for computing a compensation amount corresponding to the model based on a model representing a predetermined harmonic component of the compression torque, and a proportional / integral computing means (87)
The torque control device for a compressor according to claim 4, further comprising an adding means (88) for adding the output from the compensation model calculation means and the output from the compensation model calculation means (86) to output a voltage command. 6. The compensation model calculation means (8) responds to the fact that the predetermined speed fluctuation has been reached.
6. The torque control device for a compressor according to claim 5, further comprising a switching signal calculation means (85) that functions to attenuate or hold the compensation amount calculated and output from (6) and maintain a predetermined speed fluctuation. 7. A compensation model calculating means for two harmonic components of the compression torque.
3. The torque control device for a compressor according to claim 1. 8. A compensation model calculating means for one harmonic component of the compression torque.
3. The torque control device for a compressor according to claim 1. 9. The torque control device for a compressor according to claim 4, wherein the compressor (3) is a one-cylinder compressor (3).