JP2001270322A - Mode switch type refrigeration system control device using thermal load information, and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mode switch type refrigeration system control device using a thermal load information and a control method capable of reducing an energy consumption and enhancing a stability and an immediate responsive property of temperature control. SOLUTION: A thermal load function operator 61 operates a thermal load function value from an air temperature Tev at an inlet of evaporator 51 and an air flow rate value or a FAN set value Fn corresponding to the air flow rate value. A plurality of controllers 65 are arranged and a temperature of the respective controllers 65 can be adjusted such that a car room temperature Tin becomes a target temperature Tr. These respective controllers 65 are previously designed corresponding to the thermal load function value. The mode switch device 63 selects a controller 6 based on the thermal load function value operated by a thermal load function operator 61.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mode switching type refrigeration system controller and control method using heat load information, and more particularly to reducing the energy consumption of a refrigeration system and improving the stability and responsiveness of temperature control. The present invention relates to a mode switching type refrigeration system control device and control method using heat load information.

[0002]

2. Description of the Related Art Conventionally, temperature control of a refrigeration system includes classical control, modern control (especially optimal control), robust control,
Various methods using adaptive control theory and the like have been proposed. Classical control is suitable for designing control systems based on frequency characteristics, and modern control can be applied to multi-input multi-output systems if an accurate mathematical model is available. Robust control is effective when there is uncertainty or unknown disturbance in the control target, and adaptive control is suitable for unknown systems that change greatly.

Such a refrigeration system is a system in which physical parameters vary greatly, and high control performance cannot be expected by simply applying classical control or modern control to its temperature control. Hitherto, a method has been proposed in which parameter variation values are stored in the form of a table and a corresponding optimum control gain is obtained.

A mode switching control is known in which a plurality of controllers are designed for a controlled object that changes, and the controllers are switched according to a state or environmental change.

[0005]

However, the method for obtaining the optimum control gain presupposes the accuracy of the mathematical model, and calculates the optimum control solution using the mathematical model every time a physical parameter changes. And the burden on the computer was heavy.

In an actual control system design, an accurate mathematical model of a refrigeration system cannot always be obtained. In this case, even if a change in a physical parameter due to a change in heat load is found, an optimum control solution is obtained. You will not be able to do it.

On the other hand, the mode switching control includes a method of obtaining a plurality of controllers theoretically using a mathematical model and a method of obtaining a plurality of controllers by adjusting each state or environment without using a mathematical model. Can be considered.

The former is expected to have better control performance, but has the same weakness as the above-described method for obtaining the optimum control gain. In the latter case, a controller can be obtained empirically, but this is not always optimal.

Further, as a problem common to both, there is a problem that the control input changes discontinuously when the controller is switched. Discontinuities in the control input impact the control system and are likely to cause vibration and hunting.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and it is a mode switching type using heat load information which reduces energy consumption of a refrigeration system and improves stability and responsiveness of temperature control. It is an object to provide a refrigeration system control device and a control method.

[0011]

Therefore, the present invention provides a heat load function calculator for calculating a heat load function value from an air temperature and an air flow value at a predetermined location or a FAN set value corresponding to the air flow value. A plurality of controllers designed in advance corresponding to the magnitude of the heat load function value and capable of adjusting the temperature so that the temperature in the refrigeration system becomes the target temperature; and a heat load calculated by the heat load function calculator. A mode switch for selecting the controller based on the magnitude of the function value.

The heat load function calculator calculates a heat load function value from an air temperature and an air flow value at a predetermined location or a FAN set value corresponding to the air flow value. A plurality of controllers are provided, and each controller can adjust the temperature so that the temperature in the refrigeration system becomes a target temperature. Each controller is designed in advance in accordance with the magnitude of the heat load function value.

That is, these controllers may be configured by changing the parameters of the control elements, may be configured by changing the basic control theory itself, or may be configured by software.
Some control elements may be added or removed, or the like. The mode switch selects a controller based on the magnitude of the heat load function value calculated by the heat load function calculator.

As described above, it is possible to prevent overcooling in the refrigeration system and reduce energy consumption.
Also, switching to a controller that responds to environmental changes increases the stability of the system, thereby improving instantaneous temperature control performance.

Further, the invention is characterized in that the predetermined location is an evaporator inlet.

For example, when the refrigeration system is a car air conditioner, the air temperature at a predetermined location is the outside air temperature when outside air is introduced, and becomes the vehicle interior temperature when inside air is introduced.

Further, the present invention is characterized in that the controller has a PID controller and a speed corrector for correcting the output of the PID controller based on the rotation speed of the engine.

Further, the present invention is characterized in that a PIDF controller is provided in place of the PID controller.

By providing the controller with a filter, PI
Noise due to D control can be removed. Further, the present invention provides a controllable controller based on an input signal and an output signal of the controller before switching as an initial value of a state quantity in the controller when the controller is switched by the mode switcher. An initial value calculated based on the quasi-system is set.

On condition that the input signal and the output signal of the controller remain unchanged before and after the switching of the controller, an initial value of a state quantity in the controller is calculated based on a controllable canonical system, and this initial value is calculated in the controller. Is set as the initial value of the state quantity. Therefore, the state quantity in the controller becomes continuous before and after the switching of the controller, the control input also changes continuously, and vibration and hunting hardly occur.

Further, the present invention provides heat load information provided with a plurality of controllers which are preset in accordance with the magnitude of the heat load function value and which can adjust the temperature so that the temperature in the refrigeration system becomes the target temperature. A control method of a mode switching type refrigeration system control device, wherein a heat load function value is calculated from an air temperature and an air flow value at a predetermined location or a FAN set value corresponding to the air flow value. The controller is selected based on the size of.

[0022]

Embodiments of the present invention will be described below. First, an air conditioner of an automobile is shown in FIG. FIG.
In, the evaporator 51 is located in front of the cabin of the automobile to cool the indoor air. The condenser 53 is located in the engine room of the vehicle, and discharges heat absorbed from the room to the outside of the vehicle.

The expansion valve 55 sharply reduces the pressure of the refrigerant gas from a high pressure to a low pressure. At the inlet of the evaporator 51, a temperature sensor (not shown) for detecting the air temperature T _ev is provided. For this reason, the temperature detected by this temperature sensor is the outside air temperature when introducing outside air, and becomes the vehicle interior temperature when introducing inside air.

Next, FIG. 2 shows a configuration diagram of a mode switching type controller 60 according to an embodiment of the present invention. In Figure 2, the heat load function calculator 61 is adapted FAN setting value F _n of the cooling fan 57 to the evaporator 51 inlet air temperature T _ev and the evaporator 51 and sends the air is input.

[0025] Then, it outputs the value of the calculated thermal load on the basis of the air temperature T _ev and FAN setting value F _n, is adapted to input to mode shifter 63. In the mode switch 63, an optimum controller 65 suitable for the value of the heat load is determined by the controller NO. One is selected from 1 to 9.

[0026] Each controller 65 is supplied with the vehicle interior temperature T _in the target temperature T the temperature deviation between the _r e and the rotational speed N of the engine, the temperature deviation e based on the rotation speed N calculated results A control input u, which is a signal, is output.

FIG. 3 is a simplified control block diagram of a refrigeration system (car air conditioner) to which the mode switching controller of FIG. 2 is applied. The control input u is amplified by the PWM amplifier 67, and the variable displacement mechanism 3 of the variable displacement gas compressor 10
0 is input. FIG. 4 is a cross-sectional view of the variable displacement gas compressor 10, and FIG. 5 is a cross-sectional view taken along line AA of FIG.

The variable displacement gas compressor 10 is mounted on an automobile, and changes the state quantity of the refrigerant gas flowing into the evaporator 51 connected to the suction port 1 of the variable displacement gas compressor 10 to change the state of the automobile. It has been used so on to control the passenger compartment of the temperature T _in the target temperature T _r.

The suction port 1 sucks refrigerant gas from an evaporator 51 connected to the outside. The cylinder 3 is sandwiched between the front head 5 and the rear side block 7. A rotor 9 is rotatably arranged in the cylinder 3.

The rotor 9 is fixed to the rotating shaft 11 so as to pass therethrough. The rotating shaft 11 is driven to rotate by an engine. The outer periphery of the rotor 9 has a radially extending vane groove 1.
A vane 15 is slidably mounted in the vane groove 13. When the rotor 9 rotates, the vane 15 is urged against the inner wall of the cylinder 3 by the centrifugal force and the oil pressure at the bottom of the vane groove 13.

In the cylinder 3, a rotor 9, vanes 15,
It is divided into a plurality of small rooms by 15. These small chambers are referred to as compression chambers 17, 17...

When the volume of the compression chambers 17 changes as the rotor 9 rotates, the low-pressure refrigerant gas is sucked in from the suction port 1 and compressed by the change in volume.
A case 19 is fixed to the peripheral ends of the cylinder 3 and the rear side block 7, and a discharge chamber 21 is formed inside the case 19.

The high-pressure refrigerant gas compressed in the compression chamber 17 is
It is sent to the discharge chamber 21 via the discharge port 23 and the discharge valve 25. Then, the refrigerant gas is sent from the discharge chamber 21 to the condenser 53 via the discharge port 27.

The variable displacement gas compressor 10 has a variable displacement mechanism 30. The variable displacement mechanism 30, the discharge capacity of the refrigerant gas has a variable adjustable as by cabin temperature T _in. FIG. 6 shows a configuration example of the variable capacity mechanism 30.

The control plate 29 is disposed in the front head 5 so as to face the side of the cylinder 3. Control board 2
9 is provided with two notches 29a. The notch 29a allows communication between the inside of the cylinder 3 and the suction chamber 31 communicating with the suction port 1. On the other hand, a compression chamber 17 is formed in a portion of the control plate 29 without a notch, an inner wall of the cylinder 3 and a space closed by the vane 15.

When the control plate 29 is rotated clockwise, the notch 29
By rotating a to the right, the position where the compression chamber 17 is formed also moves to the right, and the capacity of the compression chamber 17 at this time also decreases. As described above, by rotating the control plate 29, the discharge capacity can be adjusted.

The control plate 29 is rotated by a hydraulically driven drive shaft 39 via a pin 33. By adjusting the opening of the control valve 37, oil is injected from the discharge chamber 21 into the sleeve 35, and the drive shaft 39 is caused to linearly move by the oil pressure at this time.

Then, the linear motion is converted into a rotational motion via the pin 33, and the control plate 29 is rotated. The amount of oil to be injected can be changed by changing the opening of the control valve 37. The change of the opening is performed by changing the duty ratio shown in FIG. This duty ratio corresponds to the control input u. The control plate 29 includes a sleeve 35
It is rotated to the original balance between the elastic force of the spring 38 and the control pressure P _C of the inner accordance differential pressure of the pressure P _S in the suction chamber 31.

Next, the operation of the embodiment of the present invention will be described. In a car air conditioner, the variable capacity gas compressor 10 connected to the engine shaft by a belt and rotating controls the gas refrigerant flow rate. Therefore, when the engine speed of the automobile increases, the refrigerant flow rate also increases, and the supercooling occurs. Become.

Therefore, the cooling air is reheated by the heater and sent into the vehicle interior. In addition, heat load disturbance also occurs due to a low to high temperature environment of an automobile, opening and closing of a door, heat generation by a passenger, and the like. In the present embodiment, the control mode is switched to the optimum control mode in accordance with the heat load function value that changes every moment due to the heat load disturbance.

First, the definition of the heat load function will be described. Here, it is assumed that the characteristics of the refrigeration system differ depending on the difference in the heat load. Therefore, the heat load is calculated using the heat load function
(X). x is a real variable vector and L
(X) takes a real value.

Well-known physical variables related to the heat load include an outside air temperature T _ev , a target temperature T _r , a humidity H, and an air flow rate Q. Equation 1 holds between these physical variables.

[0043]

(Equation 1)

Here, in a car air conditioner application, the target temperature _Tr should be excluded from the variables since it is assumed that the desired value is almost determined by the outside air temperature T _ev including the variation.

The air flow rate Q is set at the FAN set value _Fn.
Is determined by The humidity H is ignored this time. Therefore, the heat load function adopted here is as shown in Equation 2.

[0046]

(Equation 2)

That is, the heat load y is limited to a real value, and x represented by a transposed matrix is a real number having two components.

Next, a method of qualitatively examining the heat load function value will be described. _Outside air temperature T _ev and FAN set value F
Assuming that the heat load is determined corresponding to _n , a map as shown in FIG. 8 can be constructed. In this map, the magnitude of the heat load is evaluated using real values of 1.0 to 5.0.

The thermal load as the outside air temperature T _ev is high is large, as the value of F _n is large, around the hot air to the evaporator 51, the heat load to move heat to the refrigerant is increased to increase. Although the set value of FAN is almost proportional to the air flow rate, but not proportional to the air flow rate, the increase / decrease value for the difference in the F value at the same outside air temperature is set to a small value. Here, a heat load of 1.0 means that the heat load function value is the minimum, and a heat load of 5.0 means that the heat load function value is the maximum.

Next, a mode switching control method will be described. It is assumed that controllers 65 capable of controlling the temperature corresponding to the individual heat load function values can be individually designed.

FIG. 9 shows a configuration example of the controller 65. The PIDF controller with speed correction 70 includes a PIDF controller and a speed corrector 69. Also, this PIDF controller uses P
Made from the low pass filter 73 constant F when the ID controller 71, and outputs a control input _{u b.}

[0052] Here, _{K i} is an integration constant, the _{K d} is a differential constant, _{K p} is a proportional constant. On the other hand, the speed compensator 69
Stores a speed correction table, and corrects the duty ratio based on the input engine speed N. Therefore, to output a corrected input _{u a.}

[0053] The control input _{u b} and the correction input _{u a} are added by the adder 77, the output signal c. This output signal c
Becomes the control input u after passing through the saturation circuit 79. When saturation is detected in the saturation circuit 79, this detection signal is sent to a changeover switch 75 provided on the input side of the integrator 1 / S to prevent hunting and the like. At this time, the input signal is forcibly set to 0 value.

In the example of FIG. 8, since there are nine types of heat load function values, a maximum of nine types of controllers are designed by respectively changing K _i , K _d , K _p , time constant F, and speed correction table. Then, as shown in FIG.
So the air temperature _{T ev} and FAN setting value _{F n,} to determine with any thermal load of the nine.

Based on the result of this determination, the mode switch 63 determines the optimum controller 65 suitable for the value of the heat load by the controller NO. 1 to NO. Select one from nine. Thereafter, the temperature is adjusted by the selected controller 65.
It should be noted that if the difference between the controllers corresponding to the near heat load function values is small, they can be shared, so that the number of necessary controllers can be reduced.

As described above, it is possible to prevent overcooling of the car air conditioner and reduce energy consumption. Also, switching to a controller that responds to environmental changes increases the stability of the system, thereby improving instantaneous temperature control performance.

Next, a method of correcting the initial value of the operation amount at the time of mode switching will be described. The PIDF type controller with speed correction 70 is mounted on a computer, and is equivalently converted to a state equation type controller.

The two state variables in the state equation are stored during control and are updated at each sampling time. Therefore,
When the control mode is switched, an initial value of the state quantity of the new controller 65 is determined, and a new control is restarted under the initial value.

First, the method of calculating the initial state quantity will be described.
I do. Final input deviation e when using controller 65 before switching
And control output u (= u_a+ U _b) Is saved. However
Then u_a, U_bAre the correction input of the speed corrector 69 and
This is a control input of the low-pass filter 73.

[0060] _{Here, u a,} u _b value is determined as follows. The elements that are newly changed when switching modes are
It is _Ki , _Kd , _Kp , time constant F, and a speed correction table. This _will change the u a, _{u b} both. On the other hand, the control output u (= u
_a + _{u b)} is not changed. If it is the former u _a determination mode, after so amount uniquely determined by the rotational speed N, the following equation 3 of calculations, it is necessary to obtain the corresponding u _b.

[0061]

(Equation 3)

Next, a method for determining an internal variable of the PIDF controller will be described. The transfer function of the PIDF controller composed of the PID control unit 71 and the low-pass filter 73 is expressed as in Equation 4.

[0063]

(Equation 4)

The realization by the controllable canonical system is as shown in Equation 5.

[0065]

(Equation 5)

FIG. 10 shows a state realization model based on the controllable canonical system of the PIDF control system. Further, when Expression 5 is expanded, Expression 6 is obtained.

[0067]

(Equation 6)

However, K_i, K_p, F are non-zero.
x₁, X₂Is the state quantity, x ₁Is the integrator 1 / S
Is equivalent to the output of x₂Is the deviation e with the time constant F
This corresponds to the output passed through the pass filter 73. Controller 65
Changes, K_i, K_d, K_p, F changes, but
The difference e is instantaneously invariant and u_bThe value is also unchanged.
Thus a new appropriate x₁, X₂You should choose
No. Under the conditions so far, Equation 6 is ax₁+ Bx₂
= C-type two-variable equation. Where a, b and c are
Equation 7 is as follows.

[0069]

(Equation 7)

However, in this state, x₁, X
₂Is not uniquely determined. Then, x₂And the deviation e
From the relationship, when switching, x₂= F · e,
x₁ Is determined as shown in Equation 8.

[0071]

(Equation 8)

Therefore, as long as the system is stable after the switching, both state quantities will converge to a new equilibrium point. The above initial value correction operation is summarized in the initial value correction flow of FIG. FIG. 11 shows that four operations are required.

At the time of mounting, each coefficient of Expression 8 is set to the mode No. It is better to calculate in advance according to M. As described above, the state quantity in the PIDF controller becomes continuous before and after the switching of the controller 65, the control input also changes continuously, and vibration and hunting can be suppressed.

[0074]

Next, a specific description will be given based on a simple switching operation example. Now consider two control modes. Mode 1
_{K p = 1, K i =} 1, K d = 1 in, and _u a = 0.35 o'clock rotational speed N = N0. On the other hand, K _p = 1.5, K _i = 2.0, K _d =
0.5, u _a at the rotation speed N = N0 = 0.15.

Then, while the control system is operating, mode 1 to mode 2
And switch to U = 0.5, e just before switching
= 1.8, rotation speed N0, before switching: u = 0.5, u _a = 0.35, u
_b = 0.5-0.35 = 0.15, switched at the _{time: u a = 0.15, u b} = u-u a = 0.5-0.15 = 0.35, x 2 = F · e = 1.8 × 2 = 3.6 Thus, _{x 1} can be obtained as in equation 9.

[0076]

(Equation 9)

With the above, the initialization correction is completed. This embodiment can be realized as an electric / electronic circuit and a program on a computer. Further, the present embodiment is not limited to a car air conditioner, but can be applied to a refrigeration system in general.

[0078]

As described above, according to the present invention, since the controller is selected based on the magnitude of the heat load function value, it is possible to prevent overcooling in the refrigeration system and reduce energy consumption. Is possible. Also, switching to a controller that responds to environmental changes increases the stability of the system, thereby improving instantaneous temperature control performance.

Further, when the controller is switched, an initial value calculated based on the controllable canonical system based on the input signal and output signal of the controller before switching is used as an initial value of the state quantity in the controller. Since the control input continuously changes, vibration and hunting hardly occur.

[Brief description of the drawings]

FIG. 1 is a diagram showing an air conditioning system of an automobile.

FIG. 2 is a configuration diagram of a mode switching type controller according to an embodiment of the present invention.

FIG. 3 is a simplified control block diagram of a refrigeration system to which a mode switching controller is applied.

FIG. 4 is a sectional view of a variable displacement gas compressor.

FIG. 5 is a sectional view taken along line AA in FIG. 4;

FIG. 6 shows a configuration example of a variable capacity mechanism.

FIG. 7 is a diagram illustrating a duty ratio.

Fig. 8 Qualitative heat load map

FIG. 9 is a block diagram of a PIDF controller with speed correction.

FIG. 10 is a state realization model of a PIDF control system using a controllable canonical system.

FIG. 11 is an initial value correction flowchart.

[Description of Signs] 10 Variable displacement gas compressor 30 Variable displacement mechanism 51 Evaporator 53 Condenser 57 Cooling fan 60 Mode switching type controller 61 Heat load function calculator 63 Mode switching unit 65 Controller 69 Speed compensator 70 Speed PIDF controller with correction 71 Control unit 73 Low-pass filter

Claims (6)

[Claims] 1. A heat load function calculator for calculating a heat load function value from an air temperature and an air flow value at a predetermined location or a FAN set value corresponding to the air flow value, and a heat load function calculator corresponding to the magnitude of the heat load function value. A plurality of controllers that are designed in advance and are capable of temperature adjustment so that the temperature in the refrigeration system becomes the target temperature,
A mode switcher for selecting the controller based on the magnitude of the heat load function value calculated by the heat load function calculator. A mode switching type refrigeration system control device using heat load information. . 2. The mode switching type refrigeration system control device using heat load information according to claim 1, wherein the predetermined portion is an evaporator inlet. 3. The controller according to claim 2, wherein the controller comprises a PID controller,
A mode switching type refrigeration system control device using heat load information, comprising a speed corrector that corrects the output of the D controller based on the rotation speed of the engine. 4. A PIDF controller (a controller having a structure in which a low-pass filter having a time constant F is inserted in series with the PID controller is referred to as a PIDF controller instead of the PID controller. The same applies hereinafter). 4. The mode switching type refrigeration system control device using heat load information according to claim 3, wherein: 5. A controllable canon based on an input signal and an output signal of the controller before switching as an initial value of a state quantity in the controller when the controller is switched by the mode switch. 5. The mode switching type refrigeration system control device using heat load information according to claim 4, wherein an initial value calculated based on the system is set. 6. Mode switching using heat load information comprising a plurality of controllers designed in advance corresponding to the magnitude of the heat load function value and capable of adjusting the temperature in the refrigeration system to the target temperature. A method of controlling the refrigeration system control device, wherein a heat load function value is calculated from an air temperature and an air flow value at a predetermined location or a FAN set value corresponding to the air flow value, and the magnitude of the heat load function value is calculated. A mode switching type refrigeration system control method using heat load information, wherein the controller is selected based on the controller.