JPH02311732A - Wind-speed control apparatus for wind tunnel - Google Patents

Abstract

PURPOSE:To improve follow-up property under the stable state by performing feedback, and providing a feedforward control means. CONSTITUTION:In a low wind speed region, the rotation of a motor 3 for driving a blower 2 is controlled at a constant speed corresponding to the preset minimum wind-speed value Cmin from a minimum wind speed setting circuit 4 based on a wind-speed setting value Vsol from a chassis dynamo 1. At this time, a damper 5 undergoes feedforward control with a feedforward control circuit 6. In a high speed and wind region, feedback control is performed based on a measured wind speed value Vist from a means 7 which measures actual wind speed. The blower 2 is driven with a proportion/integration control circuit 8. Control is further performed in order to improve the response speed of the actual wind speed, namely in order to improve the follow-up property for the preset value Vsoll which is the output of the dynamo 1 and the real wind speed.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a wind speed control device for a wind tunnel.

BACKGROUND OF THE INVENTION Wind tunnels are widely used as a means to investigate the aerodynamic properties of structures such as bridges and high-rise buildings. Wind tunnels are also used to investigate the aerodynamic performance of vehicles and flying objects. Wind tunnels are also used to simulate atmospheric and weather conditions. Generally, when the object to be investigated is large, a scale model is used, and when the object to be investigated is small, the actual object is used for testing.

The wind tunnel equipment consists of a basic brush, (a) an airflow source that is a blower that causes the airflow, (b) an air conditioner that adjusts the temperature and humidity of the air, and (c) an object to be investigated. (d) a measuring device installed in the measuring section to measure the aerodynamic performance of the object to be investigated; (e) limiting the air flow locally to ensure a uniform flow; and (f) a control device for adjusting the air generation source and the air conditioner to obtain predetermined airflow conditions. This invention relates to a wind speed control device that adjusts wind speed.

Such a wind tunnel wind speed control device is known, for example, from Japanese Patent Application Laid-open No. 57
-149943 and JP-A-59-69817. In these prior art techniques, the followability of the actual wind speed to the wind speed setting value is poor, and there is a delay of several seconds or more, for example. This delay is caused by (a) when a pitot tube is used to detect the actual wind speed, the pitot tube is installed near the measuring section, which is far from the blower, and (b) the pitot tube itself is delayed. (c) The feedback control device that controls the deviation between the actual wind speed by the pitot tube and the set wind speed to zero has so-called proportional and integral action (abbreviation). P
One of the reasons for this is that since the control I) is performed, it is not possible to obtain a large gain in order to achieve stable operation.

Improving the followability of wind speed control is particularly required in wind tunnels where experiments on vehicles and the like are conducted. A chassis dynamo is provided that is rotated by the drive wheels of the vehicle, and by using the rotational speed output of this chassis dynamo as the set wind speed, it is possible to simulate the running of the vehicle while the vehicle is stopped at the measurement section. In order to do this, it is necessary to control the wind speed according to the speed of the vehicle or the wheels of the vehicle, that is, according to the rotational speed output of the aforementioned chassis dynamo. Therefore, it is necessary to use the traveling speed of the vehicle or the rotational speed of the wheels of the vehicle as the set wind speed as described above, and to make the actual wind speed quickly follow this set wind speed value.

However, as described above, in the prior art, it is not possible to improve the followability, and if an attempt is made to improve it, the proportional gain must be increased, resulting in unstable operation.

Problems to be Solved by the Invention An object of the present invention is to provide a wind tunnel wind speed control device that is stable in operation and has good followability of actual wind speed to set wind speed.

Means for Solving the Problems The present invention provides a wind speed control device for a wind tunnel in which air from a blower is blown onto a test object through a wind pipe provided with a damper, comprising means for setting the speed of the blown air. , means for detecting the wind speed of the blowing air; feedback control means for controlling the rotational speed of the blower so that the deviation between the wind speed setting means and the wind speed detecting means becomes zero; The rotation speed of
This is a wind speed control device for a wind tunnel, characterized in that it includes a feedforward control means that operates so that the rotation speed corresponds to a set wind speed.

The present invention also provides a rate-of-change limiting means that responds to the output of the wind speed setting means and replaces the set rate of change with the upper limit value when it exceeds a predetermined upper limit value. It is characterized by providing.

The present invention also provides a wind speed control device for a wind tunnel in which air from a blower is blown onto a test object through a wind pipe provided with a damper, comprising means for setting the speed of the blown air, and an output of the wind speed setting means. This is a wind speed control device for a wind tunnel, characterized in that it includes a feedforward control means for controlling an opening degree of a damper to an opening degree corresponding to a set wind speed in response to the set wind speed.

In addition, the present invention changes the opening degree of the damper over time at the upper limit value when the set rate of change in wind speed over time exceeds a predetermined upper limit value in response to the output of the wind speed setting means. The present invention is characterized by providing means for limiting the rate of change.

According to the present invention, a feedforward control means is provided which performs feedback based on the deviation between the set wind speed value and the actual wind speed, and calculates a control output directly from the set wind speed, whereby only the feedback control means is provided. This makes it possible to control the rotational speed of the blower and detect low wind speeds using the feedforward control means in a stable state without causing instability of the control system. By controlling the opening of the damper as described above, the rotation speed of the inverter that powers the motor that drives the blower can be changed from low to high wind speeds to avoid controlling the rotational speed in the region where low frequency stability is poor. Wind speed control can be performed smoothly and continuously up to the wind speed range.

Further, according to the present invention, since the change rate limiting means is provided to limit the upper limit value of the time change rate of the set wind speed, when the feedforward control means is configured with, for example, a differentiating circuit, the differential This prevents the output from becoming too large, prevents the wind speed from changing rapidly, and also reduces the stress on the mechanical structure to prevent breakdowns.

Embodiment FIG. 1 is an overall block diagram of an embodiment of the present invention. Based on the wind speed setting value Vso#l from the chassis dynamo 1, which is the wind speed setting means, in the low wind speed region, the motor 3 that drives the blower 2 operates at a constant speed corresponding to the minimum wind speed setting value Cm1n from the minimum wind speed setting circuit 4. The rotation is controlled by
At this time, the damper 5 is subjected to feedforward control by the feedforward control circuit 6. In the high wind speed range, the wind speed measurement value V from the means 7 for detecting the actual wind speed
ist, feedback control is performed to drive the blower 2 by a proportional and integral (abbreviated as P■) control circuit 8, and in order to improve the response speed of the actual wind speed, the wind speed that is the output from the chassis dynamo 1 is In order to improve the followability between the set value Vsoll and the actual wind speed,
It is controlled by a feedforward control circuit 9.

FIG. 2 is a diagram showing the overall configuration of the wind tunnel.

The entire air path is covered with a wind pipe 10, and a blower 2 is installed inside the wind pipe 10. The blower 2 is driven by the motor 3 as described above. The motor 3 is sometimes connected directly to the blower 2, but sometimes is configured to be driven via a belt or a gear train. An air conditioner 11 is provided downstream of the blower 2. The air conditioner 11 has a heat exchanger through which hot water is introduced and exchanges heat with the air in order to adjust the temperature of the airflow, and sometimes room temperature water is supplied instead of hot water. A guide vane 1 is installed inside the wind pipe 10.
2 is provided. An object to be tested, for example, a vehicle 14, is placed in the measuring section 13 where measurement experiments are performed, and a nozzle 15 for forming an airflow is placed in front. The measuring section 13 includes
Heater 16 that generates road surface heat and heater 17 that generates solar heat
etc. are provided, and together with the air conditioner 11, a thermal equilibrium state can be formed. There is a bell mouth 18 downstream of the measuring section 13, which draws the air flow diffused in the measuring section 13 into the wind pipe again. In addition to the open type in which the measuring part 13 is open as shown in FIG. 2, the measuring part 13 itself may be a closed type wind tunnel covered with a wind pipe. When the measuring part 13 is a closed type wind tunnel, In place of the nozzle 15, an airflow restrictor called a condenser and means for forming a predetermined condition for obtaining local uniformity of wind speed are provided and covered by a housing 19.

The air sucked into the bell mouth 18 is supplied to the blower 2 again. Such a wind tunnel is called a circulating wind tunnel. In addition, a wind tunnel type may be used in which the air coming out of the blower 2 is released into the atmosphere and is not supplied to the blower 2 again.

A main damper 5 is provided between the air conditioner 11 and the measuring section 13, and a bypass duct 20 is provided in front of the main damper 5. The other end of the bypass duct 20 is connected to the wind pipe 10 on the downstream side of the measurement section 13, and a bypass damper 21 is arranged near the entrance of the bypass duct 2o. The main damper 5 and the bypass damper 21 can be opened and closed, and the air passage cross-sectional areas of the main air passage wind pipe 10a and the bypass duct 20 can be adjusted respectively.

These dampers 5, 21 are configured to be interlocked by a double-acting hydraulic cylinder 22, as shown in FIG.

The dampers 5 and 21 are configured to operate in reverse so that when the opening degree of one of them increases, the opening degree of the other one decreases, and when the main damper 5 is closed, the bypass damper 21 is open. , and when the bypass damper 21 is closed, the main damper 5 is open.

The bypass duct 20 is installed to improve the airflow performance at low wind speeds, particularly the performance of wind speed control. The bypass duct 2o is also used to maintain a thermal equilibrium state. Depending on the purpose of the experiment in the measuring section 13, the bypass duct 20 and damper 21 may be omitted.

The chassis dynamo 1 provided on the floor is driven by the driving wheels of the vehicle 14, which is the object to be measured, provided in the measurement unit 13, and thereby the output corresponding to the wheel speed, that is, the vehicle speed, is adjusted to the above-mentioned wind speed setting value. It is derived as Vsoll. A pitot tube 23 is provided to measure the wind speed in the measuring section 13, and the temperature of the air supplied to the measuring section 13 is detected by a thermometer 24. The outputs from the pitot tube 23 and the thermometer 24 are given to the wind speed calculation circuit 25, and the actual wind speed Vist is thus calculated based on the first equation.

■1st=kv・(273÷te)・ΔP−(
1) Here, kv is a constant, te is the temperature measured by the thermometer 24, and ΔP is the dynamic pressure detected by the Pitot tube 23. The pitot tube 23, the thermometer 24, and the wind speed calculation circuit 25 constitute the wind speed detection means 7.

A signal representing the actual wind speed Vist is derived from the wind speed calculation circuit 25 to a line 26, and the characteristic is derived from the subtraction circuit 27 from the given circuit 5.
6 and line 28 to two subtraction circuits.

The excessive change rate of the wind speed set value Vsoll from the chassis dynamo 1 is limited by a change rate limiting circuit 29, and its output sv is given to a subtracter 31 from a line 30, and its output sv1 is further sent to a characteristic imparting circuit. 32 to a subtracter 33, whose output Svo is further fed to a subtracter 29 from line 34. The deviation ε between the signal from line 34 and the signal from line 28 is given to a PI control circuit 8 for feedback control, its output MV is passed from line 36 to an adder circuit 37, and the adder output MVO is sent to line 38. derived.

Signal MVO on line 38 is applied to adder circuit 39 . The output Cm1n from the minimum rotational speed setting circuit 4 is applied to the adder circuit 39 as described above, and the rotational speed setting value N5olr obtained in this way is applied to the motor drive circuit 41 from the line 40.

The motor drive circuit 41, which is means for controlling the rotation speed of the blower, includes a subtracter 42, a rotation speed control circuit 44, and a rotation speed detector 45 for detecting the rotation speed of the motor 3, and is configured to perform feedback control. It is composed of In this way, the blower 2 is controlled by the rotational speed setting value N5oll.

Signal SVQ from line 34 is feedforward 1
The output FF is inputted to the 1m circuit 9, and the output FF is inputted to the adder 37, thereby performing feedforward control of the motor 3 and thus the blower 2.

The signal s■ from the line 30 is given to the feedforward control circuit 6 for the damper 5, and its output SVd is given to the function generation circuit 46, which generates a signal representing the opening degree θ of the damper 5 corresponding to the input SVd on the line. 47 and applied to the damper opening degree control circuit 48.

This damper opening degree control circuit 48 has a subtracter 49, a servo controller 50, an electro-hydraulic servo valve 51, and a detector 52 for detecting the opening degree of the damper 5. The hydraulic cylinder 22 is driven in double action, the damper 5 is controlled to an opening degree corresponding to the output θ of the function generating circuit 46, and the bypass damper 21 is also driven accordingly.

The function generating circuit 46 has a characteristic that the opening degree θ of the damper 5 increases as the output SVd of the feedforward control circuit 6 increases, and this characteristic is as shown in FIG. In this way, the opening degree θ of the damper 5 is directly calculated based on the signal SVd. Therefore, as shown in FIG. 4(1), as the speed of the vehicle 14 (i.e., vehicle speed) and therefore the signal Sv corresponding to the wind speed setting value VsoZf increases, as shown in FIG. 4(1), As the opening degree of the damper 5 increases, for example, the vehicle speed increases to 40 km /
Above h, the opening is 100%.

Further, as shown in FIG. 4(2), the rotational speed of the motor 3 that drives the blower 2 is the speed of the vehicle 14, and therefore the signal SV corresponding to the wind speed setting value Vsoll is 0 to 35.
In the km/h range, Ik small rotation speed setting circuit 4
The value Cm1n is set in , and the vehicle speed is 35 km
/ h or more, motor 3
is configured such that the rotational speed of is increased. Wind speed 35~4
In the range of 0 km/h, both the damper 5 and the blower 2 are controlled, and a smooth change in the wind speed in the measuring section 13 is achieved.

In order to control the blower 2, the signal Sv on the line 30 is applied to the subtracter 31 as described above.
is given the output SVmin from the lower limit wind speed setting circuit 55. Signal S output from lower limit wind speed setting circuit 55
Vmin is the vehicle speed 35 explained in relation to FIG. 4 (2).
km/)1. The subtracter 31 calculates its output SV 1 (=SV-8Vmin) and provides it to the characteristic imparting circuit 32 . This characteristic imparting circuit 3
2 is the output of the subtracter 31, Svl, as shown in FIG.
When is negative, an output that is zero is derived, and the subtracter 31
When the output of is greater than or equal to zero, the output SVI is
is derived and given to the subtracter 33. In this way, the blower 2 operates at a wind speed SVmin (=for example, a vehicle speed of 35 k
m/h), the characteristic imparting circuit 3
The output of No. 2 is zero, and the rotation speed is controlled at a constant rotation speed Cm1n set by the minimum rotation speed setting circuit 4.

In this way, in a low wind speed region where the vehicle speed is 40 km/h or less, the opening degree of the damper 5 is adjusted to adjust the wind speed at the measuring section 13, which generally makes it difficult to detect wind speed with high accuracy at low wind speeds. A control circuit I that prevents malfunctions due to
Prevents operational instability caused by poor stability at low frequencies of the inverter included in #44. Vehicle speed 40
km/h or higher, the damper 5 is fully open, and the rotational speed of the motor 3 that drives the blower 2 is stably controlled.

The output of the lower limit wind speed setting circuit 55 is also given to a subtractor H27, and the output of this subtracter 27 is sent to the above-mentioned characteristic imparting circuit 32.
As a result, when the wind speed is below the lower limit of 5 Vrnin, the output from the characteristic providing circuit 56 to the line 28 is zero.

Although the rotational speed control circuit 44 may include an inverter, it may also be configured to control the rotational speed of the motor 3 using other configurations.

Instead of the double-acting hydraulic cylinder 22 and the electrohydraulic servo valve 51 that drive the damper 5, a power amplification circuit and a servo motor may be used, or other configurations may be used.

The signal representing the deviation ε derived from the subtractor 29 is applied to the PI control circuit R8 from the line 35 as described above. As shown in FIG. 6, the proportional gain Kp in the PI control circuit 8 is changed by the proportional gain changing circuit 57 in accordance with the actual wind speed Vist. Further, the integration time Ti of the PII control circuit 8 is also changed by the integration time change circuit 58 according to the actual wind speed Vist, as shown in No. 7 eJK. In this way, good wind speed control is achieved in line with the drastic changes in plant characteristics from low wind speed ranges to high wind speed ranges.

The PI control circuit 8 responds to the input signal of the error ε and calculates its output MV as shown in the second equation based on the outputs Kp and Ti of the circuits 57 and 58.

Here, Kp and Ti are shown by the third and fourth equations, respectively, and fi and fp are functions of the actual wind speed V i s t.

Kp −= Ip (Vist) ・
...(3) Ti = ll(Vist)
=.(4) By appropriately calculating the proportional gain Kp and the integral constant Ti in this way, control performance can be improved.

The feedforward control circuit 9 is provided to improve the followability of wind speed control. In other words, the wind speed setting value V
A motor 3 that directly drives the blower 2 according to the
By controlling the PI control circuit 8, response delay and instability peculiar to the feedback control means including the PI control circuit 8 are eliminated, and stable control with good followability is realized. A specific configuration of the feedforward control circuit 9 is shown in FIG.

This feedforward control circuit 9 has two paths, one with a gain of 0. The output UFFI is given to an adder 60 through five first amplifier circuits having a differentiator 61 and a gain K. This is the path through which the output U□2 is given to the adder 60 via the amplifier circuit 62 of □.

The output FF of the adder 60 is given to the adder 37 and P
It is added to the output MV of the I control circuit 8 and used as the output MVO for commanding the rotational speed.

As shown in FIG. 9(1), when the signal S0 from the line 34 is in an accelerated state, the differentiator 61 provides an output ΔSv to the amplifier circuit 62 at a level corresponding to its time rate of change. . Thus, the differentiator 61 serves to add energy when the blower 2 accelerates or decelerates.

By providing the differential circuit 61 in the feedforward control circuit 9, the energy necessary for accelerating the air in the blower 2 and the wind pipe IO can be reflected in the control output at the same time as the wind speed setting value Vsoll of the chassis dynamo 1 increases. Since the blower 2 and the damper 5 can be quickly driven, followability can be further improved.

By providing an amplifier circuit 62 subsequent to the differentiating circuit 61 and adjusting its gain K DFF, an acceleration state suitable for the equipment can be obtained.

The feedforward control circuit 6 for the damper 5 has a similar configuration to the feedforward control circuit 9 described above.

In another embodiment of the present invention, the feedforward control circuit 6 for the damper may be omitted and the signal SV may be directly applied to the frequency generating circuit 46.

FIG. 10 is a block diagram of a portion of another embodiment of the invention. The feedforward control circuit 9 includes an amplifier circuit 59 having a gain KllFF as shown in FIG.
This gain □ may be 1 or may be zero to inactivate its function, and its value is variable.

FIG. 11 shows a part of still another embodiment of the present invention,
The feedforward control circuit 9 includes a differentiation circuit 61 and a gain K. 1 and an amplifier circuit 62 having 1.

Furthermore, as shown in FIG. 12, the feedforward control circuit 9 may include a filter 64 interposed between the differentiating circuit 61 and the amplifier circuit 62.
This functions to alleviate an excessive rate of change in the rotational speed of the motor 3, perform stable wind speed control with good followability, and reduce the mechanical load on the mechanical structure to prevent failure.

FIG. 13 is a waveform diagram for explaining the operation of the feedforward circuit 9 shown in FIG. 12. When the step waveform shown in FIG. 13 (1) is input as the input
As the output y, the pulse shown in FIG.
is derived using a waveform that alleviates the excessive rate of change of y shown in FIG. 13(3).

FIG. 14 is a waveform diagram for explaining another operation of the feedforward control circuit 9 shown in FIG. 12. When a waveform as shown in FIG. 14 (1) is input to the differentiating circuit 61 as the input X, the differentiating circuit 61 outputs
The pulse-like waveform shown by the solid line of the 14th [U(2) is derived as follows. The filter 64 derives the waveform shown by the broken line in FIG. 14(2) as output 2. In this way,
The filter 64 functions to stabilize the rotational speed of the motor 3 as described above.

FIG. 15 shows a specific configuration of the filter 64. This filter 64 is realized by an operational amplifier 65, resistors R1 to R3, and a capacitor C1, and its transfer function G has a time constant of T and a Laplace transformer. When S is, it is expressed by the fifth equation.

G=□ (5) 1+T−s FIG. 16 is a block diagram showing another specific configuration of the filter 64. The output y of the differentiating circuit 61 is applied from a line 66 to a subtracter 67 and input to a limiter 68.

This limiter 68 has the input/output characteristics shown in FIG. 17, and derives a fixed output at the upper or lower limit when the input level is excessive. The output of the limiter 68 is input to an integrating circuit 69. The transmission ryj number G of the integrating circuit is expressed by the sixth formula % Formula % The output 2 of the integrating circuit 69 is input to a subtracter 67, and is also given to the subsequent amplifier circuit 62 shown in FIG.

To execute the filter 64 by a computer program, the input of the filter 64 is yi, the output of the filter 64 is zi, i is the number of sampling times, and α is a constant representing the size of the delay. Perform the calculation shown in Equation 7.

Zt = (1a) −yl + a・z+−+
-(7) FIG. 18 is a block diagram of a part of still another embodiment of the present invention. In this embodiment, the feedforward control circuit 9 includes a differentiating circuit 61 and a limiter 71.
and an amplifier circuit 62 having a gain Koty. That is, this limiter 71 is
It is used in place of the filter 64 of the embodiment shown in the figure. The limiter 71 operates when the output of the differentiating circuit 61 is excessive.
It works to limit its output.

FIG. 19 shows a specific configuration of the rate of change limiting circuit 29.
and a second change rate limiting circuit 73. The first rate-of-change limiting circuit 72 inputs the manual input means 74 with the switches SWI, SW2. SW3 is operated in conjunction. The switching states of the switches swi, SW2 and SW3 shown in FIG. 19 are during normal operation, that is, when the wind speed is not set to zero, and when the wind speed is set to zero,
The contact 5W1a of the switch SW1 becomes conductive, and thereby a signal from the setting circuit 75 for setting the wind speed to zero is derived,
In addition, contact 5W1b is cut off, switch SW2 is cut off,
Contact SW 3 a conducts, and contact 5W3b disconnects.

In the first rate of change limiting circuit 72, the signal from the chassis dynamo 1 is applied to the subtracter 76 via the contact 5W1b, and the signal SVA is input to the second rate of change limiting circuit 73 from the line 77a. The output of line 77a is also provided to contact S W 3 a. The signal from the wind speed zero setting circuit 75 is given to the subtraction circuit 77 from the contact 5W3b. The output of the subtraction circuit 77 is input to a limiter 78.

As shown in FIG. 20, the limiter 78 limits its output when its input is excessive. The output of the limiter 78 is input to an integrating circuit 79. The integration circuit 79 has time constants T and v, and has a transfer interval G expressed by the eighth equation.

G=□ (8) T, Ma·S The output of this integrating circuit 79 is given to the subtracting circuit 76 and also to the subtracting circuit 77 via the switch SW2.

FIG. 21 shows the first change rate limiting circuit 7 shown in FIG. 19.
2 is a graph for explaining the operation of No. 2.

Before time t1 in FIG. 21(1), the contact SW
1 a and S W 3 a are electrically connected and the signal Sv on the line 77a is outputting the wind speed Ok m/h, the damper 5 is fully closed and the blower 2 is at the minimum rotation speed. When the manual input means 74 is operated at 9 time t1 when the operation is being performed at the set value Cmin, and the switches SWI, SW2 and SW3 are brought into the switching state shown in FIG. 19, over the period from time t1 to t2, The signal SVA changes to increase over time, and at time t2, the output Vsoll of the chassis dynamo 1 increases.
The value of reaches. In this way, sudden changes in the output SVA are prevented.

The 211th again? As shown by J(2), the switch S
WI, SW2. When the switching state of SW3 is as shown in FIG. 19, the output of line 77a is the value V s of chassis dynamo 1.

11, the manual input means 74 is operated at time t3, and switches swi, SW2 . When the switching state of SW3 is changed to make the contacts 5W1a and SW3a conductive, the signal S on the line 77a is changed between time t3 and t4.
WA decreases with the passage of time and becomes zero at time t4. In this way, the output SVA on line 77 is prevented from changing suddenly. As a result, the differential circuit 61 included in the feedforward control circuit 9 (as shown in FIG.
It is possible to prevent the output shown in FIGS. 11, 12, and 18 from becoming excessively large, to prevent the wind speed from changing suddenly, and to protect the machine.

The second change rate limiting circuit 73 derives its output Sv according to the time change rate of the input signal SVA. Here Δ
When T (s) is the sampling period and j is the number of sampling times, (al) SVA+JI SV+J-++': 6 km/
h/s ・ΔT...(9) When SV+J+ = SV[J-116 km/? t/
s ・ΔT-<10) (bl) S V A (J I S V I J -11≦-
6km/h/s・ΔT...(11) When 5VIJI = SV+J-++ -6km/h/
s ・ΔT-(12)(cl) When other than the above (al) and (bl), 5VLJl = SVA+J+
-(13) FIG. 22 shows the second rate of change limiting circuit 73
FIG. 2 is a block diagram showing a specific configuration. This second change rate limiting circuit 73 includes a differentiating circuit 81, a limiter 82,
It has an integrating circuit 83. The limiter 82 has a configuration similar to that of the limiter 8 described above. When the input of the differentiating circuit 81 is xl and the output is yl, in an analog system, xl yt=□...〈14)dt In addition, this differentiating circuit 81, in a digital system, when i is the sampling number, y L = xL xL−+ ,,+
(15) Also, as shown in FIG.
1 is an operational amplifier circuit 84, a resistor R5, and a capacitor C2.
It may be configured to perform the calculation shown in Equation 16. Here, C1l is a constant.

x1 3/1=-C1l・□...
(16) dt The integration circuit 83 takes its input as x2 and its output as y2
When , the calculation of Equation 17 is performed.

y2 = (x2-dt
---<17) In a digital system, where i is the number of sampling times and ΔT is the sampling period, y2+=Σx2+−++ΔT−Δx2. =1
18a) Δx2+ = x2t −X2t−+
-(18b) As shown in FIG. 24, this integrating circuit 83 may be realized by an operational amplifier circuit 85, a resistor R6, and a capacitor C3, and configured to perform the calculation of equation 19. .

y2=-C21-! x2-dt...(1
9) Here, C21 in Equation 19 is a constant.

With reference to FIG. 25, the second change rate limiting circuit 73
When the signal shown in 7(1) is input, ASV = 5VAthlSV, J-11...(20
), as shown in FIG. 25 (2), when ΔSV exceeds the upper limit value 6 km/h/s・ΔT and the formula 9 holds true, the time mt5 to t5a
During the period, the output S■ changes according to equation 10, and becomes as shown in FIG. 25 (3). Further, ΔSV is from time t6 to t6a,
When the lower limit value -6 km/h/s·ΔT is reached between t and t7a and the above-mentioned formula 11 is satisfied, S■ changes gradually according to formula 12.

Similarly, when the signal SVA is input to the second change rate limiting circuit 73 as shown in FIG. 26(1), the output S■ becomes as shown in FIG. 26(2). That is, when the signal SVA suddenly changes from time t8 to t8a,
At time 8~tab, the above-mentioned formula 9 holds true, and the output Sv
changes rapidly. Similarly, time t9 to t9a
When the signal SVA suddenly changes at , the above-mentioned equation 11 is established from time t9 to t9b, and the output S■ changes gradually.

In addition, as shown in FIG. 27, the input SVA is as shown in FIG. 27 (
As shown in FIG. 27(2), when neither of the above-mentioned equations 9 and 11 holds true, that is, when the signal SVA changes slowly, the output S becomes the input as shown in FIG. 27(2). It has the same waveform as S■A, and at this time, the above-mentioned formula 13 is established. In this way, the set value SV for the blower 2 is prevented from changing suddenly.

Since the PIillIItN circuit 8 for feedback, the feedforward control circuit 9, and the change rate limiting means 29 are provided at the front stage of the feedforward control circuit 6, the wind speed setting value Vso is controlled from the chassis dynamo 1.
When ll contains noise, or due to fluctuations due to the resolution of the analog/digital conversion circuit, it is possible to prevent the output of the subsequent differentiating circuit 61 from occurring and disturbing the control system.

Further, according to the present invention, the following configuration is adopted to prevent the inverter included in the motor 3 and the rotational speed control circuit 44 from stopping and tripping due to overload. With this configuration, operation continues under overload, but overload operation for a long period of time is prevented. Trip refers to detecting when some abnormality occurs and stopping the operation of equipment or equipment. In this embodiment, even if an overload occurs, the trip does not occur immediately, but if the overload continues to occur (for example, for one minute), this is detected and the operation is stopped to protect the equipment and equipment. . The purpose of this configuration is to prevent operation from stopping due to overload and to improve the efficiency of experiments. Another objective is to keep equipment capacity low and reduce costs. In other words, the purpose of this configuration is to detect when an overload occurs and prevent equipment or devices from remaining in an overload area for a long time.

A line 88 to which power is supplied from the rotational speed control circuit 44 of the motor 3 is provided with eight current transformers for detecting the load current, as shown in FIG.

The outputs of these eight current transformers are input to a comparator circuit 90 shown in FIG. The comparison circuit 90 has a so-called hysteresis characteristic, as shown in FIG. 29. This comparator circuit 90 has a predetermined overload value Ia (
For example, if the current exceeds 120% of the rated current, the logic becomes "1".
, ie, an output that is on, and then derives a logic "0", ie, an output that is off, when the load current falls below a value Ib below the rated current (eg, 90% of the rated current).

The output of the comparison circuit 90 is input to an overload limiting circuit 91 which is an overload control means.

A specific configuration of the overload limiting circuit 91 is shown in FIG. In FIG. 30, a line 35 from which a signal representing the deviation ε is derived is input from a line 92 to a subtracter 93 after being multiplied by a gain 99 from a line 1oo via a contact 5W4a of a switch SW4. The output of the subtracter 93 is applied to a limiter 94 to limit excessive input, and then applied to an integrating circuit 95. Integrating circuit 95
has a transfer function G expressed by Equation 21.

TLM here? represents the time constant.

The output of this integrating circuit 95 is given to the subtracting circuit 33 as well as to the subtracting circuit 93 .

The output of the wind speed zero setting circuit 75 is given to the line 92 via the contact 5W4b. Switch SW4 is the comparator circuit 9
In response to an output of 0, when that output is a logic "IJ,"
When the contact 5W4a is conductive and the contact 5W4b is cut off, and the output of the comparison circuit 90 is logic r OJ, the contact SW4a is cut off as shown in FIG.
Make W4b conductive.

For example, when the output of chassis dynamo 1 is accelerating,
When the output of the comparator circuit 90 becomes logic "1" and turns on, the deviation ε>0, so the output LMT of the integrator circuit 95 is positive, and the signal SV2 given via the characteristic imparting circuit 32 is reduced by the subtraction circuit 33, so that the wind speed set value from the chassis dynamo 1 is apparently limited to a small value. In other words, the sudden acceleration that causes the overload is weakened and the signal SvO on the line 34 is reduced, so that the inverter included in the motor 3 and the rotational speed control circuit 44 that controls it can escape from the overload region. do.

Referring to FIGS. 30 and 31, as the deviation ε derived to line 35 of subtractor 29 changes, the positive output given to subtraction circuit 33 from integration circuit 95 changes over time. signal on line 92 and integrator circuit 95.
and the signal applied to the subtraction circuit 93 via line 96 are equal, so that the signal applied from the subtraction circuit 93 to the line 9
The signal applied to the integrating circuit 95 via the limit and the ivy 94 becomes zero, and the output LMT of the integrating circuit 95 becomes proportional to the deviation ε.

Therefore, as shown in FIG. 32, during rapid acceleration, the time rate of change of the signal S0 from the subtraction circuit 33 is:
The angle θ1 corresponding to the output LMT of the integrating circuit 95 is lowered, and the sudden acceleration is weakened.

This prevents the motor 3 and the inverter from leaving the overload region and tripping them, as described above.

The current transformer 89 detects that the load current of the motor 3 has decreased, and the load current has a value Tb (see FIG. 29).
When it becomes less than
Switching from the state shown in the figure, a signal indicating that the wind speed is zero is given from the wind speed zero setting circuit 75. As a result, the output of the integrating circuit 95 decreases with the passage of time, and the output of the integrating circuit 95 decreases over time.
The output of 5 becomes zero. As a result, the overload limiting circuit 91
has no effect on the PI control circuit 8 and feedforward control circuit 9 for the blower 2.

FIG. 33 shows the next embodiment 6. That is, the output of the means for calculating the rate of change of the wind speed setting means may be used in addition to the above-mentioned deviation as an input to the overload limiting circuit.

The means for calculating the rate of change of the wind speed setting means comprises a change rate calculator 104 and a gain 105. The output Sv derived from line 101 is input to rate of change calculator 104 . The calculation formula of the rate of change calculator 104 is expressed by Formula 22, where J is the number of sampling times.

DSV = 5V-J, -SV, J-11-(22)
However, DSV is the output of the rate of change calculator.

The output of the rate of change calculator 104 is amplified at a gain 105 via line 102, and is input as DSVI via line 103 to the overload limiting circuit in the same way as the deviation.

The explanation after I)3V1 is input to the overload limit circuit is as follows.
This is the same as the explanation of the embodiment when the deviation is input.

Further, as shown in FIG. 34, the input N5oll of the means for calculating the rate of change of the means for controlling the rotational speed of the blower by +X may be used as the input to the overload limiting circuit.

The difference between the means for calculating the rate of change of the wind speed setting means and the means for calculating the rate of change of the means for controlling the rotational speed of the fan is that in the means for calculating the rate of change of the wind speed setting means, the input is the wind speed setting value. and the input of the means for calculating the rate of change of the means for controlling the rotational speed of the blower is to use the input of the means for controlling the rotational speed of the blower.

Further, FIG. 35 shows the next embodiment. That is, in addition to subtracting the output of the overload limiting circuit from the output of the wind speed setting means, the output LMT of the overload limiting circuit may be subtracted from the input of the means for controlling the rotational speed of the blower.
Input N5ole derived from line °40 via
is subtracted from the subtractor 107. Subtractor output N5
oll 1 is input via line 108 to means for controlling the rotational speed of the blower.

FIG. 36 shows a configuration in which the input of the overload control means is the output of the means for calculating the rate of change in the output of the wind speed setting means, and the output of the overload control means is subtracted from the output of the wind speed setting means. .

In FIG. 37, the input of the overload control means is the output of the means for calculating the rate of change of the output of the wind speed setting means, and the overload 5I
A configuration is shown in which the output of the Ja1 means is subtracted from the input of the means for controlling the rotational speed of the blower.

In FIG. 38, the input of the overload control means is the output of the means for calculating the rate of change of the means for controlling the rotational speed of the blower, and the output of the overload control means is subtracted from the output of the wind speed setting means. Show the configuration.

FIG. 39 shows that the input of the overload control means is the output of the means for calculating the rate of change of the means for controlling the rotational speed of the blower;
A configuration is shown in which the output of the overload control means is subtracted from the input of the means for controlling the rotational speed of the blower.

Such an overload limiting circuit 91 is connected to the chassis dynamo 1.
It also operates when the motor 3 suddenly decelerates, thereby causing the motor 3 to perform regenerative braking.

The present invention can be implemented in connection with circulating wind tunnels and single flow wind tunnels, and can also be implemented with respect to wind tunnels that do not have dampers 5, 21, and furthermore, dampers 5, 21.
, 21 may have a pneumatic servo system in addition to a hydraulic or electric type, and the rotational speed of the motor 3 may be controlled not only by an inverter but also by other configurations.

In the above embodiment, the current transformer 89 is used as an example of overload detection means, but the amount of electric power supplied to the motor may be used instead. The amount of electric power can be detected by known means. Furthermore, a torque meter may be attached to the motor shaft, and this torque meter may be used as an overload detection means.Furthermore, an electronic thermal circuit consisting of a motor drive circuit and a bimetal is provided,
This may allow overload to be detected.

As another embodiment of the present invention, a vane opening degree control device may be provided instead of a rotation speed control device using an inverter device or the like.

Generally, the wind speed can be adjusted by changing the rotation speed of the blower, but inverter devices are expensive. The electric motor that drives the blower rotates at a constant speed in synchronization with the power supply frequency, and vanes are installed at the inlet (upstream) or outlet (downstream) of the blower to adjust the circuit cross-sectional area, and the wind speed is changed by adjusting the opening of this vane. You can also do that.

In the case of a wind tunnel facility having such a configuration, the present invention can be implemented by providing a device for controlling the opening degree of the vane instead of the rotation speed control device.

Effects of the Invention As described above, according to the present invention, stable wind speed control with good followability, which is difficult to achieve using only the feedback control means, can be easily performed using the feedforward control means.

[Brief explanation of drawings]

FIG. 1 is an overall block diagram of an embodiment of the present invention, and FIG.
M is a wind tunnel system diagram of an embodiment of the present invention, FIG. 3 is a graph showing the characteristics of the function generator 46 having characteristics that compensate for the nonlinear characteristics of the damper, and FIG. 5 is the characteristics of the characteristic imparting circuit 32.56. FIG. 4 is a graph showing the control characteristics of the damper 5 and motor 3, FIG. 6 is a graph showing the characteristics of the gain change circuit, FIG. 7 is a graph showing the characteristics of the integral time change circuit 58, and FIG. 9 is a block diagram showing the configuration of the feedforward circuit 9, FIG. 9 is a graph showing the characteristics of the feedforward circuit 9, FIG. 10 is a block diagram showing another configuration of the feedforward control circuit 9, and FIG. 11 is a graph showing the characteristics of the feedforward circuit 9. A block diagram showing another configuration of the feedforward control circuit 9, FIG. 12 is a block diagram showing another configuration of the feedforward control circuit 9, FIGS. 13 and 14 [! l is a waveform diagram showing the characteristics of the filter 64 shown in FIG. 12;
FIG. 15 is a graph showing a specific configuration of the filter 64;
FIG. 16 is a block diagram showing another specific configuration of the filter 64, FIG. 17 is a graph showing the characteristics of the limiter 68, FIG. 18 is a block diagram showing another configuration of the feedforward control circuit 9, and FIG. 20 is a block diagram showing a specific configuration of the rate-of-change limiting means 29, FIG. 20 is a graph for explaining the operation of the limiter 78 included in the first rate-of-change limiting circuit 72, and FIG. 21 is a graph showing the first change. A waveform diagram for explaining the operation of the rate limiting circuit 72, FIG. 22 is a waveform diagram for explaining the operation of the rate limiting circuit 72.
23 is a block diagram showing a specific configuration of the second rate-of-change limiting circuit 73 included in FIG. Electric circuit diagrams showing the configuration; FIGS. 25, 26, and 27 are waveform diagrams for explaining the operation of the second rate-of-change limiting circuit 73; FIG. 28 is a current transformer 89 for overload detection. 29 is a diagram for explaining the operation of the comparison circuit 90, FIG. 30 is a block diagram showing the specific configuration of the overload limiting circuit 91, and FIGS. 31 and 32 are
33, 34 and 35 are block diagrams showing embodiments of a pond having an overload limiting circuit, and FIGS. 36 and 37. , FIG. 38, and FIG. 39 are block diagrams showing the configuration of other embodiments having an overload limiting circuit. 1...Chassis dynamo, 2...Blower, 3...
Motor, 5.21... Damper, 6, 9... Feedforward control circuit, 7... Wind speed detection means, 8...
PI control circuit, 10... Wind pipe, 13... Measuring section, 1
4... Object to be tested, 29... Rate of change limiting circuit, 89
...Current transformer, 90...Comparison circuit, 91...Overload limit circuit Agent Patent attorney Keiichi Saikyo Figure 3 e ('/,) Figure 5 Input Sv1 Chapter 41 Angle 14/ )Rice shop (km/h) Kasagetsu 14/) Speed (km/h) Figure 8 Figure 10 Figure 95I! Special opening time 111 m2 Fig. 13 Sunny time 1 m2 Fig. 14 Kikuma time 15 Fig. 16 Fig. 1121 Fig. time Time 232 242 25 ffi Time Fig. 26 4 m j 1271! Time Time Figure 28 Figure 29 rzt Ib Ia Current

Claims (4)

[Claims] (1) A wind speed control device for a wind tunnel that blows air from a blower to a test object through a wind pipe provided with a damper, including means for setting the wind speed of the blowing air and detecting the wind speed of the blowing air. feedback control means for controlling the rotation speed of the blower so that the deviation between the wind speed setting means and the wind speed detection means becomes zero; and feedback control means for controlling the rotation speed of the blower in response to the output of the wind speed setting means.
1. A wind tunnel wind speed control device comprising: feedforward control means that operates to achieve a rotation speed corresponding to a set wind speed. (2) In response to the output of the wind speed setting means, when the time rate of change of the set wind speed exceeds a predetermined upper limit value, change rate limiting means is provided, which is realized by replacing the set rate with the upper limit value. A wind speed control device for a wind tunnel according to claim 1, characterized in that: (3) In a wind speed control device for a wind tunnel that blows air from a blower to a test object through a wind pipe provided with a damper, a means for setting the wind speed of the air to be blown out, and a response to the output of the wind speed setting means. and feedforward control means for controlling the opening degree of the damper so that the opening degree corresponds to the set wind speed. (4) In response to the output of the wind speed setting means, when the set rate of change over time of the wind speed exceeds a predetermined upper limit value, the opening degree of the damper is changed over time by the upper limit value. 3. The wind tunnel wind speed control device according to claim 2, further comprising change rate limiting means.