JP5105854B2 - Operation control method for inverter-driven compressor and inverter-driven compressor - Google Patents

Description

  The present invention provides an operation control method for an inverter-driven compressor that uses a three-phase motor as a drive source and controls the operation of the compressor by changing the frequency of the alternating current input to the three-phase motor by an inverter, and the operation control method. The present invention relates to an inverter driven compressor.

  The inverter-driven compressor 1 includes a three-phase motor 15 as a drive source for the compressor body 10, and an inverter 30 is disposed between the three-phase motor 15 and a power source, and the inverter 30 inputs the power from the power source to the motor 15. The configuration is such that the rotational speed of the motor 15 can be controlled by changing the frequency of the alternating current (see FIG. 1).

Such motor rotation speed control by the inverter 30 is, for example, a compression supplied to the consumption side by providing a pressure detection means 60 such as a pressure sensor in a supply pipe 50 for supplying compressed gas to the consumption side. with sensing pressure P _d of the gas compressor, according to the pressure P _d of the compressed gas pressure detecting means 60 detects, by performing the rotation speed control of the motor 15 by the inverter 30, to be supplied to the consumer the pressure P _d of the gas is always controlled to be constant, also performs switching control of the suction port 10a of the compressor body 10 by operating the suction valve 41 in response to the pressure P _d of the compressed gas.

As an example, it sets the pressure of the compressed gas to be supplied to the consumer as a target pressure P _t, and set the no-load operation start pressure P _ul which is a predetermined high pressure to the target pressure P _t, the actual is the pressure of the compressed gas supplied to the consumer in the discharge-side pressure P _d of the compressor body 10 so as to coincide with the target pressure P _t, the discharge-side pressure P _d exceeds the target pressure P _t When the pressure detecting means 60 detects this, the frequency of the alternating current output to the motor 15 is decreased to shift the motor 15 to low speed operation, while the discharge side pressure P _d of the compressor body 10 is the target pressure P _t. If it falls below, the alternating current of the frequency _{fmax which} rotates the motor 15 at high speed is output to the motor 15, and the operation control which transfers the motor 15 to high speed operation is performed. When the pressure detection means 60 detects that the discharge side pressure is equal to or higher than the no-load operation start pressure, the suction valve 41 is operated to close the suction port 10a of the compressor body 10 and shift to the no-load operation. When the pressure detection means 60 detects that the discharge side pressure has decreased below the target pressure, the suction valve 41 is operated to open the suction port 10a of the compressor body 10 and shift to load operation.

In the inverter-driven compressor 1 configured as described above, the compressor main body 10 acts as a load on the motor 15, and the discharge side pressure of the compressor main body 10 is reduced to reduce the compressor main body 10. When the power required for driving decreases, the load on the motor 15 also decreases. For this reason, when the pressure of the compressed gas to be supplied to the consumer side (target pressure P _t ) is lowered, there is a margin in the output of the motor 15 as the pressure is lowered.

However, in the case of the conventional compressor, even when the pressure P _{t of the} compressed gas to be supplied to the consumer side is lowered, the maximum rotational speed N _max of the motor 15 (therefore, the frequency of the alternating current that generates this rotational speed). f _max), to which has been fixed to the fixed without changing this margin of the motor 15 caused by the drop in the target pressure P _t, the motor 15 has been used in not sufficiently exhibit its ability .

Therefore, in order to be able to perform the operation with the maximum performance of the motor 15, the maximum rotational speed N _max of the motor is made variable, and the set pressure (target) of the compressed gas supplied to the consumption side is set. There has been proposed an inverter-driven compressor in which the maximum rotational speed N _max of the motor can be increased as the pressure P _t ) is reduced (see Patent Document 1).

Prior art document information of the present invention includes the following.
Japanese Patent Laid-Open No. 9-209949

According to the invention described in the above-mentioned Patent Document 1, as described above, it is generated in the motor 15 by reducing the pressure (target pressure P _t ) set as the target value of the pressure of the compressed gas to be supplied to the consumer side. By rotating the output margin to increase the number of revolutions, the motor 15 is operated in a state where its capacity is fully exhibited, and the upper limit value of the discharge side pressure that can be set is 0.83 MPa. If the rotation speed of the motor that generates the rated power is 100%, the motor rotation speed can be increased by 20% when the set discharge side pressure is reduced to 0.59 MPa, and the motor can be operated at a rotation speed of 120%. I am doing so.

However, in the compressor control method described in Patent Document 1, the relationship between the discharge side pressure set value (P) and the maximum rotation speed ratio (x) is expressed by the following equation:
P = −0.0125x + 2.08
By regarded as linear change ( "0027" column and FIG. 4 of Patent Document 1), as shown in FIG. 5, the maximum value P _H of the discharge side pressure set value P, the rated output at the maximum value P _H A point A indicating the rotational speed N ₁ , a minimum value P _L of the discharge side pressure, and a point C indicating the rotational speed N _{3 at} which the rated output is obtained at the minimum value P _L are obtained, and the maximum value of the discharge side pressure is obtained. When the discharge pressure setting value P of the compressor is variable between P _H and the minimum value P _L , the maximum rotational speed (ratio) of the motor according to the change of the setting value P is a straight line connecting the points AC. Since it is determined according to (two-dot chain line in FIG. 5), the motor is operated in a state exceeding the rated output.

  That is, the correspondence between the change in the discharge side pressure P of the compressor body 10 and the change in the rotational speed N of the motor 15 that generates the rated output does not actually change linearly. As indicated by the solid line, the curve changes in accordance with a curved line that slightly bulges downward, and is assumed to be a straight line connecting the points A and C. The correspondence indicated by the two-dot chain line in FIG. There is a gap between the relationship.

Therefore, when the rotational speed of the motor is controlled in accordance with the AC line indicated by a two-dot chain line in FIG. 5, the motor is set except for the case where the discharge side pressure set value P is set to the maximum value P _H or the minimum value P _L. 15 is operated exceeding the rated output.

In particular, the set value of the discharge pressure of the compressor body 10, when set in the vicinity of the intermediate value P _M between the maximum value P _H and the minimum value P _L at the discharge side pressure significantly exceeds the highest output, at a rotational speed N ₂ is actually when the FIG. 5, the intermediate value P _M despite generating a rated output as an example, the motor is higher than the rotational speed N ₂ two, are operated at a rotational speed N _{2 '} The Rukoto.

  By the way, the motor 15 for driving the compressor main body is generally used with a margin for output, and within a predetermined allowable range (for example, exceeding about 10% of the rated output). , It is designed so that it can be operated without any trouble even if it exceeds the rated output.

However, when the motor 15 is operated beyond the above-mentioned allowable range with respect to the rated output of the motor 15, for example, a protection device provided in the inverter 30 is operated and the compressor is designed to make an emergency stop. Therefore, when the maximum number of rotations N _max of the motor 15 is controlled by the above-described control method, there is a possibility that the compressor may be brought to an emergency stop.

  Therefore, in order to avoid such an emergency stop, the straight line A-C indicated by a two-dot chain line in FIG. 5 is parallel to the lower side so that the motor 15 is not operated exceeding the rated output. It is also conceivable to shift and obtain the A′-C ′ straight line passing through the point B, and to control the rotational speed of the motor 15 according to this.

However, when controlling the maximum speed N _max of the motor 15 in accordance with the A'-C 'lines, the maximum value P _H of the discharge pressure, lower than the rotational speed N ₁ which generates the rated output, the rotation speed The motor is driven at N ₁ ′, and the motor is operated with a margin more than necessary for its output.

Further, even at the lowest value P _L of the discharge side pressure, the operation is performed at a rotational speed N ₃ ′ that is excessively lower than the maximum rotational speed N _{3 at} this pressure P _L. The performance is not fully demonstrated.

As described above, the change in the set value P _t of the discharge-side pressure, if the relationship between the change of the maximum rotational speed N _max of the motor, captures a linear change determining maximum speed N _max of the motor, The wider the setting range of the discharge side pressure of the compressor, the larger the gap between the actual maximum rotational speed N _max and the set maximum rotational speed N _max '.

Therefore, by changing the pulley provided on the output shaft of the motor 15 or the input shaft of the compressor main body, the speed increasing ratio when the power of the motor 15 is transmitted to the compressor main body 10 is made variable. the base of the compressor, the maximum pressure P _H ~ intermediate pressure and the high-pressure specifications and variable discharge-side pressure to P _M, a low-pressure specification that the setting of the discharge pressure variable in a range of intermediate pressure P _M ~ minimum pressure P _L It is conceivable that the motor speed can be selectively set to any one of the following specifications. In this case, the high speed ratio is set high for the low pressure specifications, and the high speed ratio is set low for the high pressure specifications. Adjust so that can be fully demonstrated.

In this way, even if the compressor can be used in either the high-pressure specification or low-pressure specification mode by changing the setting, as shown in FIG. _The pressure and frequency on the discharge side of the compressor change linearly between _H and the intermediate pressure P _{M and} between the intermediate set pressure P _M and the minimum set pressure P _L for the low pressure specification, as shown by the solid line in FIG. In order to control the motor on the assumption, the maximum frequency f _max ′ determined based on the assumed straight line and the maximum frequency f according to the discharge side pressure-maximum frequency curve (two-dot chain line in FIG. 6) There may be a deviation from _max and the motor may be operated at the rated output or higher. However, the set pressure between the maximum pressure P _H and the minimum pressure P _L described above is used for both high and low pressure specifications. The changeable pressure range is narrowed to 1/2 compared to a compressor with variable pressure Therefore, the deviation between the assumed pressure-frequency line and the actual pressure-frequency curve can be made relatively small, and even if the motor is controlled based on the assumed pressure-frequency line. The motor does not greatly exceed the rated value, and this can be stopped within the allowable output range of the motor, and the emergency stop device provided in the inverter does not operate and the compressor does not make an emergency stop.

However, in the above control method, the pressure range that can be set in one compressor is either the maximum set pressure P _H to the intermediate set pressure P _M or the intermediate set pressure P _M to the minimum set pressure P _L. In the compressor described in the above-mentioned Patent Document 1, the set pressure is variable in the entire range from the maximum set pressure P _H to the minimum set pressure P _L without changing the setting of the speed increasing device such as the pulley. In comparison, the setting range of the discharge side pressure is limited.

Moreover, since the slope of the discharge-side pressure P-maximum frequency f _max line, which is the reference for control, differs between the high-pressure specification and the low-pressure specification, the control program to be incorporated differs depending on whether the setting is high or low. There is a problem that cannot be achieved.

In each of the conventional techniques described above, the maximum motor speed N _max or the maximum frequency at which the maximum engine speed N _max is generated in response to the setting change of the discharge side pressure (target pressure P _t ) of the compressor. relates to a method for changing the settings of f _max, for example in the case of setting the target pressure P _t to the maximum set pressure P _H is the maximum speed makes the motor rated output N _max (maximum frequency f _max) is It is specified as the rotational speed N ₁ (frequency f ₁ in FIG. 5 and frequency f ₄ in FIG. 6), and the motor 15 is operated so as not to exceed the rotational speed N _max specified here.

However, the pressure of the compressed gas supplied to the consumption side, that is, the discharge side pressure P _d of the compressor body 10 always changes according to the consumption amount of the compressed gas on the consumption side, and in the above example, the discharge side pressure P _{When d} is less than the maximum set pressure P _H , the motor does not reach the rated output even when the motor is operated at the rotational speed N ₁ (for example, P _M where the discharge side pressure P _d is lower than the maximum set pressure P _H. If this is the case, the rated output is not reached until the motor speed is increased to N ₂ ). If the output margin generated in this way can be used to increase the number of revolutions, it is convenient to operate the motor 15 more efficiently.

  Accordingly, an object of the present invention is to solve the above-described drawbacks of the prior art, and in the inverter-driven compressor, the settable pressure range can be widened, and the settable pressure range is as described above. Inverter-driven compressor control that ensures that the power of the compressor body does not exceed the rated power, or even if the power exceeds the rated power, can be exceeded within the specified tolerance range It is an object of the present invention to provide an inverter-driven compressor that realizes the method and the control method.

Further, in response to the pressure P _d changes in the compressed gas supplied to the consumer, always the motor control method of the inverter-driven compressor which becomes possible to maximize the capability, and realizes the control method inverter An object is to provide a drive compressor.

In order to achieve the above object, the inverter-driven compressor 1 that realizes the first operation control method of the present invention applies to the motor 15 in accordance with the change in the target pressure P _t of the compressed gas to be supplied to the consumer side. It is configured so that the setting of the maximum frequency f _max of the input AC current can be changed.
A three-phase motor 15 for driving the compressor body 10, an inverter 30, a pressure detecting means for detecting the compressor body 10 of the outlet-side pressure P _d to change the frequency of the alternating current input to the three-phase motor 15 ( provided with a pressure sensor 60), based on the detected pressure of the pressure sensing means 60, the discharge-side pressure P _d of the compressor body 10, and controls the inverter 30 so as to match a predetermined target pressure P _t given In an inverter driven compressor provided with a control device 2 that outputs an alternating current of a frequency,
The control device 2 is
The maximum value P _H and the minimum value P _L that can be set as the target pressure P _t are stored, the pressure change between the maximum value P _H and the minimum value P _L, and the motor corresponding to the pressure change storing approximately represents the equation within a predetermined tolerance by the correspondence between the change in frequency f _max for generating a rotational speed N _max, which forms the rated output, combining multiple linear equation Storage means;
Based on the set target pressure P _t , the maximum frequency f _max of the alternating current input to the motor is calculated by the calculation formula, and a control signal having the calculated maximum frequency (f _max ) as an upper limit is calculated. A speed control signal output unit 22 for outputting to the inverter 30 is provided (claims 1 and 6).

The storage means replaces the calculation formula formed by combining the plurality of straight line expressions with a change in pressure between the maximum value P _H and the minimum value P _L, and the motor is rated according to the change in the pressure. may as storing formulas approximate representation curve the relationship between the change in the frequency f _max for generating a rotational speed N _max within a predetermined tolerance which forms the output (claim 2, wherein Item 7).

と，前記目標圧力Ｐ_tが，前記中間値Ｐ_M未満であるときに適用される最高周波数ｆ_maxの計算式

を前記複数の直線の式としてそれぞれ記憶すると共に，
前記速度制御信号出力部が，設定された前記目標圧力Ｐ_tに基づいて，前記いずれかの計算式により前記最高周波数ｆ_maxを算出する演算処理部（図示せず）を備えるものとして構成しても良い（請求項３，請求項８）。 In the inverter-driven compressor 1 of the arrangement, the storage unit 23 of the controller 2, the a maximum value P _H, the frequency f ₁ to the motor 15 to the rated output at outermost high P _H, the minimum value P _L When the frequency f ₃ to the motor 15 to the rated output at the minimum value P _L, and an intermediate value P _M and the maximum value P _H and the minimum value P _L, the motor 15 rated output in the intermediate value P _M And store the frequency f ₂
A based on the set the target pressure P _t a calculation formula for obtaining the maximum frequency f _max, the target pressure P _t is, calculation of the maximum frequency f _max to be applied when the at intermediate value P _M or more formula

And a calculation formula for the maximum frequency f _max applied when the target pressure P _t is less than the intermediate value P _M.

Are respectively stored as the plurality of straight line expressions,
The speed control signal output unit is configured to include an arithmetic processing unit (not shown) that calculates the maximum frequency f _max by any one of the calculation formulas based on the set target pressure P _t. (Claim 3 and Claim 8).

を前記曲線の計算式として記憶すると共に，
前記速度制御信号出力部２２が，設定された前記目標圧力Ｐ_tに基づいて，前記計算式により前記最高周波数ｆ_maxを算出する演算処理部（図示せず）を備えるものとして構成しても良い（請求項４，請求項９）。 Further, in the storage unit 23 of the control device 2, the a maximum value P _H, the frequency f ₁ to the motor 15 to the rated output at outermost high P _H, wherein the minimum value P _L, in the minimum value P _L Each of the frequencies f _{3 at} which the motor 15 is rated output is stored, and
Formula for _{obtaining the} maximum frequency f _max based on the set target pressure P _t

Is stored as a formula for calculating the curve,
The speed control signal output unit 22 may be configured to include an arithmetic processing unit (not shown) that calculates the maximum frequency f _max by the calculation formula based on the set target pressure P _t. (Claims 4 and 9).

を前記曲線の計算式として記憶すると共に，
前記速度制御信号出力部２２が，設定された前記目標圧力Ｐ_tに基づいて，前記計算式により前記最高周波数ｆ_maxを算出する演算処理部（図示せず）を備えるもの，として構成しても良い（請求項５，１０）。 As still another configuration, the storage means 23 of the controller 2, the a maximum value P _H, the frequency f ₁ to the motor 15 to the rated output at outermost high P _H, and the minimum value P _L, the frequency f ₃ to the motor 15 to the rated output at the lowest value P _L, and an intermediate value P _M and the maximum value P _H and the minimum value P _L, the frequency of the motor 15 to the rated output at the intermediate value P _M memorize each f ₂ ,
Formula for _{obtaining the} maximum frequency f _max based on the set target pressure P _t

Is stored as a formula for calculating the curve,
The speed control signal output unit 22 may be configured to include an arithmetic processing unit (not shown) that calculates the maximum frequency f _max by the calculation formula based on the set target pressure P _t. Good (claims 5 and 10).

The inverter-driven compressor 1 that realizes the second operation control method of the present invention has the highest AC current input to the motor 15 according to the change in the pressure P _d of the compressed gas discharged from the compressor body 10. The frequency f _max can be changed.
In the same inverter-driven compressor 1, the control device 2 of the inverter-driven compressor 1 stores the maximum value P _H and the minimum value P _L in the range that can be set as the target pressure P _t , and the maximum the change in pressure between the value P _H and the minimum value P _L, a corresponding relationship between the change in frequency to generate the rotational speed made by the rated output of the motor 15 in response to a change in pressure, a plurality of straight lines of formula Storage means for storing a calculation expression approximately expressed within a predetermined allowable error range by combining
Based on the discharge side pressure P _d of the compressor body 10 detected by the pressure detection means 60, the maximum frequency f _max of the alternating current input to the motor 15 is calculated by the calculation formula, and the calculated maximum frequency Is provided with a speed control signal output unit 22 for outputting a control signal for causing the inverter 30 to output the control signal (claims 11 and 16).

The storage means replaces the calculation formula formed by combining the plurality of straight line expressions with a change in pressure between the maximum value P _H and the minimum value P _L, and the motor is rated according to the change in the pressure. may as storing formulas approximate representation curve the relationship between the change in the frequency f _max for generating a rotational speed N _max within a predetermined tolerance which forms the output (claim 12, wherein Item 17).

と，前記吐出側圧力Ｐ_dが，前記中間値Ｐ_M未満であるときに適用される最高周波数ｆ_maxの計算式

を前記複数の直線の式としてそれぞれ記憶すると共に，
前記速度制御信号出力部が，前記圧縮機本体の吐出側圧力Ｐ_dに基づいて，前記いずれかの計算式により前記最高周波数ｆ_maxを算出する演算処理部（図示せず）を備えるものとして構成しても良い（請求項１３，１８）。 Further, in the inverter-driven compressor 1 having a control device 2 of the structure, in the storage unit 23 of the control device 2, the maximum value P _H and the frequency to the motor rated output at outermost height P _H f ₁ , the minimum value P _L , the frequency f _{3 at} which the motor is rated output at the minimum value P _L , and
An intermediate value P _M between the maximum value P _H and the minimum value P _L and a frequency f _{2 at} which the motor 15 is rated output at the intermediate value P _M are respectively stored.
A calculation formula for obtaining the maximum frequency f _max, based on the discharge side pressure P _d of the compressor body, wherein the pressure detection means detects the discharge pressure P _d is, when the at intermediate value P _M or more Of maximum frequency f _max applied to

And a calculation formula for the maximum frequency f _max applied when the discharge side pressure P _d is less than the intermediate value P _M.

Are respectively stored as the plurality of straight line expressions,
The speed control signal output unit includes an arithmetic processing unit (not shown) that calculates the maximum frequency f _max by any one of the above formulas based on the discharge side pressure P _d of the compressor body. (Claims 13 and 18).

を前記曲線の計算式として記憶すると共に，
前記速度制御信号出力部が，前記圧縮機本体の吐出側圧力Ｐ_dに基づいて，前記計算式により前記最高周波数ｆ_maxを算出する演算処理部（図示せず）を備えるものとしても良い（請求項１４，１９）。 Motor addition, the storage unit 23 of the controller 2, the a maximum value P _H, the frequency f ₁ to the motor rated output at outermost high P _H, and the minimum value P _L, in the minimum value P _L And memorize the frequency f _{3 for} which
Based on the discharge side pressure P _d of the compressor body 10 detected by the pressure detection means, a calculation formula for obtaining the maximum frequency f _max is as follows:

Is stored as a formula for calculating the curve,
The speed control signal output unit may include an arithmetic processing unit (not shown) that calculates the maximum frequency f _max by the calculation formula based on the discharge-side pressure P _d of the compressor body. Item 14, 19).

を前記曲線の計算式として記憶すると共に，
前記速度制御信号出力部２２が，前記圧縮機本体１０の吐出側圧力Ｐ_dに基づいて，前記計算式により前記最高周波数ｆ_maxを算出する演算処理部（図示せず）を備えるものとして構成しても良い（請求項１５，２０）。 Also, the storage unit 23 of the controller 2, the a maximum value P _H, the frequency f ₁ to the motor 15 to the rated output at outermost high P _H, wherein the minimum value P _L, in the minimum value P _L The frequency f _{3 at} which the motor 15 is rated output, the intermediate value P _M between the maximum value P _H and the minimum value P _L , and the frequency f _{2 at} which the motor is rated output at the intermediate value P _M are stored. Along with
Formula for obtaining the maximum frequency f _max based on the discharge side pressure P _d of the compressor body detected by the pressure detection means

Is stored as a formula for calculating the curve,
The speed control signal output unit 22 includes an arithmetic processing unit (not shown) that calculates the maximum frequency f _max by the calculation formula based on the discharge side pressure P _d of the compressor body 10. (Claims 15 and 20).

With the configuration of the present invention described above, the inverter-driven compressor according to the present invention can change the maximum frequency f _max output from the inverter 30 and thus the maximum rotation speed N _max of the motor 15 in accordance with the setting of the target pressure P _t. is a of the control method, even when the wide setting range of the target pressure P _t, prevent the motor without being operated well beyond the rated output, the compressor is emergency stop did it.

Further, since the frequency, and hence the motor speed, can be increased so as not to decrease the output of the motor as the target pressure P _t decreases, the motor 15 can be used at full capacity and is economical. , The amount of air supplied to the consumer side could be increased.

  Furthermore, since the pressure setting range was widened, two types of compressors, high-pressure specifications and low-pressure specifications, could be shared as a single compressor.

  In addition, the pressure setting range can be widened only by a relatively simple change in the configuration by changing the calculation formula in the conventional control program, and there is no need to change the structure of the compressor.

Inverter-driven compression of the present invention in which the pressure change of the compressed gas supplied to the consumption side is measured by the discharge side pressure P _d of the compressor body 10 and the maximum frequency f _max of the alternating current output to the motor 15 is variable. in the control method of the machine, even when the wide setting range of the target pressure P _t, without the motor is operated well beyond the rated output, that the compressor emergency stop I was able to prevent it.

Further, for example, even if the discharge side pressure P _d detected by increasing the consumption of compressed gas on the consumption side suddenly decreases, by increasing the frequency f _max and operating the motor 15 at high speed, The supply of compressed gas was increased, and it was possible to respond immediately to the increase in compressed gas consumption on the consumer side.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 is an inverter-driven compressor. In the illustrated embodiment, the inverter-driven compressor 1 is a compressor main body 10 and a drive source for the compressor main body 10. A motor 15 and an inverter 30 that converts the frequency of the alternating current from the power source and outputs the same to the motor 15 are provided. By driving the compressor body 10 by the motor 15, the suction port 10a of the compressor body 10 is provided. A compressed gas, that is, air in the illustrated example, is introduced into the cylinder of the compressor body 10 through the connected intake valve 41, and the compressed gas introduced into the cylinder is compressed by the rotation of the rotor. The obtained compressed air is configured to be discharged from the discharge port 10 b of the compressor body 10.

  In this embodiment using an oil-cooled screw compressor that injects lubricating oil into the cylinder and compresses and discharges the compressed gas as the compressor body 10, the lubrication is performed by the compressor body 10. A receiver tank 17 into which compressed gas discharged together with the oil is introduced is provided, the compressed gas and the lubricating oil are separated in the receiver tank 17, and the separated compressed gas is supplied to the consumption side through the supply pipe 50. At the same time, the lubricating oil recovered in the receiver tank 17 is supplied to the oil supply port 10c of the compressor body 10 through the oil supply circuit.

Capacity control device The inverter drive type compressor 1 having the basic configuration as described above includes a speed control means (inverter 30) for controlling the rotational speed of the compressor body 10 by controlling the rotational speed of the motor 15, and a compression The detection signal from the pressure control means 40 for detecting the pressure of the compressed gas supplied to the consumption side and the pressure of the compressed gas supplied to the consumer side in the present embodiment, the suction control means 40 for controlling the amount of air to be compressed. On the basis of this, there is provided a capacity control device comprising a control device 2 for outputting a control signal for controlling the operation of each part of the speed control means 30 and the suction control means 40.

The speed control means 30 described above detects the discharge side pressure P _d of the compressor body 10 detected by the pressure detection means 60 such as a pressure sensor (in the present embodiment, the pressure in the supply pipe 50 described above). Is controlled so as to coincide with a preset target pressure P _t, and thus the rotation speed of the compressor body 10 driven by the motor 15 is controlled. Depending on the discharge side pressure P _d of the compressor body 10, opening / closing control or opening degree control of the suction valve 41 provided at the suction port 10 a of the compressor body 10 is performed, so that the compressor body 10 is compressed. and controlling the intake amount of gas, by a such speed control as suction control, the discharge pressure P _d of the compressor body 10, closer to the target pressure P _t, a substantially consuming the compressed gas constant pressure Can be supplied It is configured so that.

Suction control means The above-described suction control means 40, which is one of the constituent elements of the above-described capacity control device, includes a suction valve 41 provided in the suction port 10a of the compressor body 10 and the suction valve in the illustrated embodiment. It comprises a conduit 42 communicating between the pressure receiving chamber of the valve 41 and the receiver tank 17 and an electromagnetic valve 43 for controlling the opening and closing of the conduit 42, and a control signal from the control device 2 to be described later is sent to the solenoid valve. 43, the solenoid valve 43 is controlled to open and close to operate the suction valve 41, the suction amount of the compressor body 10 is controlled, and the discharge side pressure P _d (supplied to the consumption side) of the compressor body 10 is controlled. controlled so that the pressure of the compressed gas) is set target pressure P _t.

In the present embodiment, the discharge-side pressure P _d of the compressor body 10 is equal to or no-load operation start pressure P _ul or set as a predetermined high pressure to a predetermined target pressure P _t, below the controller 2 outputs a control signal to the electromagnetic valve 43 to operate the above-described electromagnetic valve 43, whereby the intake valve 41 is operated in a no-intake state with the intake port 10a of the compressor body 10 closed (no load operation). Then, when the pressure P _d in the supply pipe 50 drops below the target pressure P _t stored in the storage means, the control device 2 controls the electromagnetic valve 43 to open the suction valve 41, thereby compressing it. The suction port 10a of the machine body 10 is opened, and the operation shifts to the load operation.

Speed control means Speed control for controlling the operating speed of the compressor body 10 by controlling the rotational speed of the motor 15 by operating in accordance with the pressure change of the compressed gas supplied to the consumption side together with the suction control means 40 described above. Means 30 are provided.

This speed control means 30 is composed of an inverter 30 that converts an alternating current from a power source into a desired frequency and outputs it to a motor 15 that drives the compressor body 10. The pressure P _d is detected by the pressure detection means 60, and the discharge side pressure P _d is set to the target pressure P so that the discharge side pressure P _{d of} the compressor body 10 matches the target pressure P _t according to the detection signal. _{When the} pressure detection means 60 detects that _t has been exceeded, the frequency of the alternating current output to the motor 15 is reduced based on a control signal from the control device 2 to be described later, and the motor 15 is shifted to low speed operation and consumed. the pressure P _d of the compressed gas supplied to the side is, when falls below a predetermined target pressure P _t, in accordance with a control signal from the control unit 2, maximum frequency f _max which forms the motor 15 and speed operation And is configured to output an alternating current to the motor 15.

Control Device The control device 2 for controlling the inhalation control means 40 and the speed control means 30 is constituted by an electronic control device or the like storing a predetermined program, and a central processing unit (not shown) of the electronic control device. ) Activates the previously stored program and controls each part according to the program, so that the suction control means 40 is based on a detection signal from the pressure detection means 60 provided on the discharge side of the compressor body 10. An inhalation control signal output unit 21 that outputs a predetermined control signal and a speed control signal output unit 22 that outputs a predetermined control signal to the speed control means 30 are realized.

Suction control signal output unit The above-described suction control signal output unit 21 starts the no-load operation based on a detection signal from a pressure detection means (pressure sensor) 60 that detects a pressure change in the supply pipe 50. When the pressure is _{equal to} or higher than P _ul , the suction control means 40 is controlled to close the suction port 10a of the compressor body 10, and the pressure of the compressed gas supplied to the consumption side is less than a predetermined target pressure P _t . Then, a control signal is output to the suction control means 40 so that the suction control means 40 opens the suction port 10a of the compressor body 10.

  In the configuration of the suction control means 40 shown in FIG. 1, the suction control signal output unit 21 controls the electromagnetic valve 43 that controls the start / stop of introduction of compressed gas in the receiver tank 17 with respect to the working pressure chamber of the suction valve 41. , A control signal for controlling the opening and closing of the electromagnetic valve 43 is output to perform the operation.

When the speed control signal output unit foregoing speed control signal output unit 22 based on the detection signal from the pressure sensing means 60, the discharge-side pressure P _d of the compressor body 10, which exceeds the target pressure P _t, above When the control signal for reducing the frequency of the alternating current output to the motor 15 is output to the inverter 30 that is the speed control means, and the pressure of the compressed gas supplied to the consumption side becomes less than the target pressure P _t , A control signal is output to the inverter 30 to output an alternating current of the maximum frequency f _max that makes the motor 15 operate at high speed.

The maximum frequency f _max output from the inverter 30 by the speed control signal output unit 22 is determined by one of the following methods.

Determination of the maximum frequency f _max based on the set value of the target pressure P _{t When} the maximum frequency f _max is determined by the target pressure P _t , the maximum pressure that can be set as the target pressure P _t in the storage means of the control device 2 in advance. A calculation formula that approximates the correspondence between the change in pressure between the value P _H and the minimum value P _L and the frequency at which the motor generates a rated output in response to this change in pressure is stored. When the target pressure _Pt is input / set by operating an operation key provided on the operation panel 1 or the like, the arithmetic processing unit (not shown) of the speed control signal output unit 22 receives the input target pressure Pt. _{From t} , the maximum frequency f _max is calculated based on the calculation formula, the calculated f _max is stored in the storage means 23, and the maximum frequency output from the inverter 30 is calculated from the calculated f _max by the calculation. Set as Controlling said inverter Te.

Thereby, in the inverter drive compressor 1 of the present invention, the maximum frequency f _max is changed with the change of the pressure setting of the compressed gas supplied to the consumer side (change of the target pressure P _t ). When the setting for reducing the pressure _Pt is changed, it is possible to obtain a margin generated in the motor 15 due to the pressure drop, an increase in the maximum frequency f _max , and thus an increase in the rotational speed of the motor. .

Determination of the maximum frequency f _max based on the detected pressure P _{d When} the maximum frequency f _max is determined based on the measured value of the discharge side pressure P _d of the compressor body 10, the pressure P _d can be previously stored in the storage means 23. A calculation formula that approximates the correspondence between the change in pressure between the maximum value P _H and the minimum value P _L and the frequency at which the motor 15 generates a rated output in response to this change in pressure is stored. An arithmetic processing unit (not shown) of the speed control signal output unit 22 is identified by the received detection signal in accordance with a detection signal from the pressure detection means 60 that detects the pressure in the supply pipe 50 that supplies compressed gas to the consumption side. Based on the calculated pressure P _d , the maximum frequency f _max is calculated based on the calculation formula, and based on the calculated f _max , the maximum frequency f _max of the alternating current output to the inverter 30 is changed as needed (FIG. 3). (B))

As a result, in the inverter driven compressor 1 of the present invention, the maximum frequency f _max increases when the detected discharge side pressure P _d decreases, for example, when the consumption of compressed gas on the consumption side increases. Thus, it is possible to increase the supply amount of compressed gas to the consumption side by rotating the motor 15 at a high speed.

Correspondence Relationship between Target Pressure _Pt or Detected Pressure _Pd and Maximum Speed _{fmax As} described above, the maximum frequency _fmax of the alternating current input to the motor 15 is set to the target pressure _Pt or the compressor body 10. to derive on the basis of the discharge side pressure P _d, correspondence between change in the target pressure P _t, or sensed pressure P _d, and the frequency for generating the rated output to the motor 15 with respect to the change of the pressure (maximum frequency f _max) In the present invention, the following calculation formula is used as an approximate expression of the relationship.

In the following description, the example in which the maximum frequency f _max is obtained based on the discharge side pressure P _d of the compressor body 10 detected by the pressure detection means 60 has been shown, but instead of this, the target pressure P _{t is used.} When the maximum frequency f _max is obtained, the target pressure P _t that is input and set via the input key or the like on the operation panel may be substituted for the discharge side pressure P _d in the equation.

Approximate correspondence 1
In the present embodiment, as the first of the approximate representation of the above-mentioned correspondence relationship, the maximum frequency f _max is obtained by two equations: an equation representing the straight line AB shown in FIG. 3 and an equation representing the straight line _BC. The coordinates of the points A, B, and C are the maximum value P _H , the minimum value P _L and the intermediate value P _M that the pressure P _d in the supply pipe 50 can take, Each of these pressures is represented by frequencies f ₁ , f ₂ , and f ₃ that cause the motor 15 to generate a rated output.

In the present embodiment, by example, by operating the input keys provided on the operation panel, the frequency f ₁ to generate a rated output of the motor at the highest value P _H and the maximum value P _H, and the minimum value P _L frequency f ₃ to generate a rated output of the motor at the minimum value P _L, and the maximum value P _H and the minimum value P _L intermediate value P _M, and the frequency f for generating the rated output to the motor in the intermediate value P _{M When 2} is input, the input numerical values are stored in the storage means of the control device described above, the stored pressure values, the highest frequencies f _{1 to} f ₃ in the pressure values, and the pressure detection means The pressure P _d in the supply pipe 50 detected by 60 is substituted into either of the following “Equation 1” or “Equation 2”, and the maximum frequency f _max to be output under this condition is obtained.

Which of “Expression 1” and “Expression 2” is used to determine the maximum frequency f _max is determined by the pressure P _d of the compressed gas detected by the pressure detecting means 60, and the compressed gas detected by the pressure detecting means 60 When the pressure P _d is equal to or higher than the intermediate value P _M , the frequency f _max to be output by the inverter 30 is determined by “Equation 1”, and the pressure P _{d of the} compressed gas detected by the pressure detecting means 60 is the intermediate value. If it is less than P _M , the maximum frequency f _max that the inverter 30 should output is determined by “Equation 2”, and the pressure detection means 60 that detects the pressure P _{d of the} compressed gas supplied to the consumption side during operation. According to the detection signal from, f _max is calculated by one of the following formulas.

A diagram schematically representing the correspondence between the change in the discharge side pressure _{Pd and} the change in the maximum frequency f _max by the above-described “Expression 1” and “Expression 2” is as shown by a solid line in FIG.

The correspondence between the change in the discharge side pressure P _{d and} the change in the maximum frequency f _max is actually slightly swelled downward as shown by the broken lines passing through points A, B and C in FIG. because a curve, generates the rated output to the motor 15 at the maximum value P _H and the pressure can take the pressure P _d of the compressed gas supplied to the consumer as the prior art described with reference to FIG. 5 The point A representing the frequency f _{1 is connected} to the minimum value P _{L that} can be taken by the pressure P _{d of the} compressed gas supplied to the consumer side, and the point C representing the frequency f _{3 at} which the motor 15 generates a rated output at this pressure. When the rotational speed of the motor 15 is approximately controlled by the straight line A-C, the motor 15 may exceed the rated power beyond the allowable range in the vicinity of the intermediate value P _M. and when the pressure P _d is equal to or higher than the intermediate value P _M, medium By parted calculation formula for obtaining the maximum frequency f _max and the case of less than a value P _M, the motor 15 according to the corresponding relationship approximating a curve showing the actual relationship between the discharge side pressure P _d and the maximum frequency f _max It became possible to control the rotation speed.

Note that the formula 1, even by the highest frequency f _max, which is calculated by Equation 2 when controlling the motor 15, or regarded as varying the maximum frequency f _max linearly, motor 15 is rated output Although when operated excess to occur, since the divided a method of calculating the maximum frequency f _max the intermediate value P _M as a boundary as mentioned above, even this excess occurs, the excess predetermined It is possible to keep within the allowable range, and it is possible to suitably prevent the compressor from being emergency stopped.

  In addition, since the motor 15 can be operated at the rated output, the motor 15 can be used to its full capacity and economical, and the amount of air supplied to the consumption side can be increased.

  In addition, the pressure setting range can be widened, and two types of compressors, high-pressure specifications and low-pressure specifications, can be used as a single compressor.

Moreover, instead of the formula for calculating the maximum frequency f _max of the conventional control program, the above two types of formulas for calculating the maximum frequency f _max are added, and the frequency calculated by any one of the formulas based on the detected pressure is calculated. By simply changing the configuration by simply adding the control program to be selected, the pressure setting range can be widened and there is no need to change the compressor structure.

When the maximum frequency f _max obtained by the above formulas 1 and 2 exceeds the maximum frequency f ₃ at the minimum set pressure P _L , regardless of the maximum frequency f _max obtained by the above formulas 1 and 2. The operation may be performed at the maximum frequency f _{3 at} the minimum set pressure P _L.

Approximate correspondence 2
As described above, in the formulas 1 and 2 described with reference to FIG. 3, the intermediate value P _{M in the} range that the discharge side pressure P _d can take is a boundary, and in the case where the value is equal to or greater than the intermediate value P _M. maximum frequency f _max and the calculation of, by divided the equation for calculating the maximum frequency f _max in the case of less than the intermediate value P _M, relatively simple changes and the highest frequency f _max of the discharge pressure P _d by formula However, instead of this, as shown in FIG. 4, a hyperbola connecting points A and C is obtained by calculation, and this hyperbola is detected by the pressure detecting means 60. and changes in pressure P _d, as approximately representing a change in the frequency of generating the rated output to the motor 15 with respect to the change of the pressure P _d, to control the rotational speed of the motor 15 on the basis of the hyperbola, The motor 15 operates exceeding the rated output beyond the allowable range. It can also be as to not.

  In order to obtain such a hyperbola, an expression to be stored by the storage means 23 of the control device 2 is shown in “Expression 3”.

As described above, the expression shown as “Expression 3” is stored in the storage means 23 of the control device 2, and the value of the pressure P _d that can be obtained by operating the operation key provided on the operation panel is set. By inputting the maximum value P _H , the frequency f ₁ at which the rated output is generated in the motor at this pressure, the minimum value P _{L at} which the pressure P _d can be taken, and the frequency f ₃ at which the rated output is generated in the motor 15 at this pressure. The speed control signal output unit 22 of the control device 2 calculates the maximum frequency f _max at which the motor 15 is operated at the rated output, based on the compressed gas pressure P _d detected by the pressure detection means 60.

Therefore, the speed control signal output unit 22 of the control device 2 outputs a control signal for causing the inverter 30 to output the calculated maximum frequency f _max to the inverter 30, and the input maximum frequency f _max Thus, the motor 15 generates a rated output.

Even if the motor 15 may be operated exceeding the rated output due to the input of the maximum frequency f _max , this excess can be kept within the allowable range described above.

Incidentally, the control of the motor 15, so that never exceed a frequency f ₃ corresponding to the set minimum set pressure P _L, the maximum frequency f _max, which is calculated based on the equation 3, the minimum pressure P _L When the frequency f ₃ in the above is exceeded, the motor 15 is driven by the f ₃ regardless of the calculation result by the equation 3.

In the control method of the present embodiment configured as described above, instead of the conventional control method in which the motor 15 is controlled based on an expression representing a “straight line” connecting the point A and the point C, the point A The maximum frequency f _max to be input to the motor 15 is determined on the basis of an expression representing a “curve” (hyperbola) that forms a curved shape that swells downward and slightly bulges downward, and this maximum frequency f an alternating current of _max enter that controls the rotational speed of the motor 15 to the motor 15, the actual discharge pressure P _d and the maximum frequency f _max, based on the curve approximation and the curve showing the relationship between the maximum frequency f _max can be obtained, and the output of the motor 15 can be prevented from exceeding the rated output beyond the allowable range. Therefore, the compressor 1 can be prevented from performing an emergency stop or the like.

  Further, since the frequency, that is, the number of revolutions of the motor 15 can be increased so as to increase the power of the compressor body 10 with respect to the rated output of the motor 15, the motor 15 can always be used at its full capacity and is economical. At the same time, the amount of air supplied to the consumer can be increased.

  In addition, the pressure setting range can be widened, and two types of compressors, high-pressure specifications and low-pressure specifications, can be used as a single compressor.

In addition, the pressure setting range can be widened and the structure of the compressor can be changed by simply replacing the equation for calculating the maximum frequency f _max in the conventional control program with the aforementioned equation for calculating the hyperbola. There is no need.

Approximate correspondence 3
In the above description of the second approximate correspondence relationship, the correspondence relationship between the discharge side pressure and the frequency is approximately obtained by an equation for obtaining a hyperbola passing through points A and C in each graph, and thereby the rotational speed of the motor 15 is obtained. However, an equation for obtaining a quadratic curve passing through all points A, B, and C according to the following “Equation 4” is stored in the storage means 23 of the control device 2, thereby The correspondence relationship between the side pressure and the frequency may be approximately obtained to control the rotation speed of the motor 15.

According to the control method of the present embodiment configured as described above, the correspondence relationship between the discharge side pressure _Pd and the maximum frequency _fmax is approximately defined by the quadratic curve passing through the point B. The rotation speed of the motor 15 can be controlled by approximating the pressure P _d and the maximum frequency by a curve representing the relationship of f _max , and the output of the motor 15 can be made closer to the rated output.

Schematic explanatory drawing of an inverter drive compressor. The functional block diagram of a control apparatus. Table showing the first approximate correspondence between the pressure P _d and the maximum rotational speed f _max. Table showing the second and third approximate correspondence between the pressure P _d and the maximum rotational speed f _max. The chart which shows the correspondence of the setting pressure and the maximum number of rotations which were used by the conventional control. The chart which shows the correspondence of the setting pressure and the maximum number of rotations which were used by the conventional control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inverter drive compressor 2 Control apparatus 21 Suction control signal output part 22 Speed control signal output part
221 Arithmetic processing unit 23 Storage means 10 Compressor body 10a Suction port 10b Discharge port 10c Refueling port 15 Motor 17 Receiver tank 30 Speed control unit (inverter)
40 Suction control means 41 Suction valve 42 Pipe line 43 Solenoid valve 50 Supply piping 60 Pressure detection means (pressure sensor)

Claims (20)

A three-phase motor for driving the compressor body, an inverter for changing the frequency of the alternating current input to the three-phase motor, pressure detection means for detecting the discharge side pressure (P _d ) of the compressor body, Control that outputs an alternating current of a predetermined frequency by controlling the inverter so that the discharge side pressure (P _d ) of the compressor body matches a predetermined target pressure (P _t ) based on the detection pressure of the detection means. In an inverter driven compressor equipped with a device,
Set the maximum value (P _H ) and the minimum value (P _L ) of the range that can be set as the target pressure (P _t ),
A correspondence relationship between a change in pressure between the maximum value (P _H ) and the minimum value (P _L ) and a change in frequency that generates a rotation speed that makes the motor a rated output in response to the change in pressure, By combining multiple linear equations, a calculation formula that is approximately expressed within a predetermined tolerance range is set.
Based on the set pressure as the target value (P _t), and calculates the calculating formula I Ri highest frequency (f _max), the calculated out the maximum frequency (f _max) of the upper and eggplant alternating current Is output to the inverter. An operation control method in an inverter drive compressor. A three-phase motor for driving the compressor body, an inverter for changing the frequency of the alternating current input to the three-phase motor, pressure detection means for detecting the discharge side pressure (P _d ) of the compressor body, Control that outputs an alternating current of a predetermined frequency by controlling the inverter so that the discharge side pressure (P _d ) of the compressor body matches a predetermined target pressure (P _t ) based on the detection pressure of the detection means. In an inverter driven compressor equipped with a device,
Set the maximum value (P _H ) and the minimum value (P _L ) of the range that can be set as the target pressure (P _t ),
Predetermined correspondence between the change in pressure between the maximum value (P _H ) and the minimum value (P _L ) and the change in frequency that generates the rotational speed at which the motor makes a rated output in response to the change in pressure. Set the calculation formula of the curve approximately expressed within the tolerance of
Based on the set pressure as the target value (P _t), and calculates the calculating formula I Ri highest frequency (f _max), the calculated out the maximum frequency (f _max) of the upper and eggplant alternating current Is output to the inverter. An operation control method in an inverter drive compressor. Said maximum value (P _H), the frequency of the motor rated output at outermost height _{(P H) (f 1)} ,
The minimum value (P _L ), the frequency (f ₃ ) at which the motor is rated output at the minimum value (P _L ), and
An intermediate value (P _M ) between the maximum value (P _H ) and the minimum value (P _L ) and a frequency (f ₂ ) at which the motor is rated output at the intermediate value (P _M ) are obtained, respectively.
When the set target pressure (P _t ) is equal to or greater than the intermediate value (P _M )

And determine the maximum frequency (f _max ) according to
When the target pressure (P _t ) is less than the intermediate value (P _M )

The operation control method for an inverter-driven compressor according to claim 1, wherein the maximum frequency (f _max ) is determined according to: Said maximum value (P _H), the frequency of the motor rated output at outermost height _{(P H) (f 1)} ,
The minimum value (P _L ) and the frequency (f ₃ ) at which the motor is rated output at the minimum value (P _L ) are obtained,
Based on the set target pressure (P _t ),

3. The operation control method for an inverter-driven compressor according to claim 2, wherein the maximum frequency (f _max ) is determined according to: Said maximum value (P _H), the frequency of the motor rated output at outermost height _{(P H) (f 1)} ,
The minimum value (P _L ), the frequency (f ₃ ) at which the motor is rated output at the minimum value (P _L ), and
An intermediate value (P _M ) between the maximum value (P _H ) and the minimum value (P _L ) and a frequency (f ₂ ) at which the motor is rated output at the intermediate value (P _M ) are obtained, respectively.
Based on the set target pressure (P _t ),

3. The operation control method for an inverter-driven compressor according to claim 2, wherein the maximum frequency (f _max ) is determined according to: A three-phase motor for driving the compressor body, an inverter for changing the frequency of the alternating current input to the three-phase motor, pressure detection means for detecting the discharge side pressure (P _d ) of the compressor body, Control that outputs an alternating current of a predetermined frequency by controlling the inverter so that the discharge side pressure (P _d ) of the compressor body matches a predetermined target pressure (P _t ) based on the detection pressure of the detection means. In an inverter driven compressor equipped with a device,
The control device is
The maximum value (P _H ) and the minimum value (P _L ) of the settable range are stored as the target pressure (P _t ), and the pressure change between the maximum value (P _H ) and the minimum value (P _L ) Corresponding to the change in pressure and the change in frequency that generates the rotational speed of the motor as a rated output, the approximate relationship can be approximated within a predetermined tolerance by combining a plurality of linear expressions. Storage means for storing the calculation formula expressed in
Based on the set target pressure (P _t ), the maximum frequency (f _max ) of the alternating current input to the motor is calculated by the calculation formula, and the calculated maximum frequency (f _max ) is set as the upper limit. An inverter-driven compressor comprising a speed control signal output unit that outputs a control signal to the inverter. A three-phase motor for driving the compressor body, an inverter for changing the frequency of the alternating current input to the three-phase motor, pressure detection means for detecting the discharge side pressure (P _d ) of the compressor body, Control that outputs an alternating current of a predetermined frequency by controlling the inverter so that the discharge side pressure (P _d ) of the compressor body matches a predetermined target pressure (P _t ) based on the detection pressure of the detection means. In an inverter driven compressor equipped with a device,
The control device is
The maximum value (P _H ) and the minimum value (P _L ) of the settable range are stored as the target pressure (P _t ), and the pressure change between the maximum value (P _H ) and the minimum value (P _L ) And a calculation formula of a curve that approximately represents a correspondence relationship between a change in frequency and a change in frequency that generates a rotational speed that makes the motor a rated output corresponding to the change in pressure within a predetermined allowable error range. Storage means;
Based on the set target pressure (P _t ), the maximum frequency (f _max ) of the alternating current input to the motor is calculated by the calculation formula, and the calculated maximum frequency (f _max ) is set as the upper limit. An inverter-driven compressor comprising a speed control signal output unit that outputs a control signal to the inverter. The storage means of the control device comprises:
Said maximum value (P _H), the frequency of the motor rated output at outermost height _{(P H) (f 1)} ,
The minimum value (P _L ), the frequency (f ₃ ) at which the motor is rated output at the minimum value (P _L ), and
An intermediate value (P _M ) between the highest value (P _H ) and the lowest value (P _L ) and a frequency (f ₂ ) at which the motor is rated output at the intermediate value (P _M ) are stored respectively.
A calculation formula based on the set the target pressure (P _t) obtaining the maximum frequency (f _max), applies when the target pressure (P _t) is the said intermediate value (P _M) or Formula for maximum frequency (f _max )

And a calculation formula for the maximum frequency (f _max ) applied when the target pressure (P _t ) is less than the intermediate value (P _M ).

And remember each
The speed control signal output unit includes an arithmetic processing unit that calculates the maximum frequency (f _max ) by any one of the calculation formulas based on the set target pressure (P _t ). Item 7. The inverter-driven compressor according to item 6. The storage means of the control device comprises:
Said maximum value (P _H), the frequency of the motor rated output at outermost height _{(P H) (f 1)} ,
The minimum value (P _L ) and the frequency (f ₃ ) at which the motor is rated output at the minimum value (P _L ) are stored respectively.
Formula for _{obtaining the} maximum frequency (f _max ) based on the set target pressure (P _t )

And remembering
It said speed control signal output unit, based on the set the target pressure (P _t), according to claim 7, characterized in that it comprises an arithmetic processing unit for calculating the maximum frequency (f _max) by the equation Inverter driven compressor. The storage means of the control device comprises:
Said maximum value (P _H), the frequency of the motor rated output at outermost height _{(P H) (f 1)} ,
The minimum value (P _L ), the frequency (f ₃ ) at which the motor is rated output at the minimum value (P _L ), and
An intermediate value (P _M ) between the highest value (P _H ) and the lowest value (P _L ) and a frequency (f ₂ ) at which the motor is rated output at the intermediate value (P _M ) are stored respectively.
Formula for _{obtaining the} maximum frequency (f _max ) based on the set target pressure (P _t )

And remembering
It said speed control signal output unit, based on the set the target pressure (P _t), according to claim 7, characterized in that it comprises an arithmetic processing unit for calculating the maximum frequency (f _max) by the equation Inverter driven compressor. A three-phase motor for driving the compressor body, an inverter for changing the frequency of the alternating current input to the three-phase motor, pressure detection means for detecting the discharge side pressure (P _d ) of the compressor body, Control that outputs an alternating current of a predetermined frequency by controlling the inverter so that the discharge side pressure (P _d ) of the compressor body matches a predetermined target pressure (P _t ) based on the detection pressure of the detection means. In an inverter driven compressor equipped with a device,
A maximum value (P _H ) and a minimum value (P _L ) of a range that can be set as the target pressure (P _t ) are set, and
A correspondence relationship between a change in pressure between the maximum value (P _H ) and the minimum value (P _L ) and a change in frequency that generates a rotation speed that makes the motor a rated output in response to the change in pressure, By combining multiple linear equations, a calculation formula that is approximately expressed within a predetermined tolerance range is set.
Based on the discharge side pressure (P _d ) of the compressor main body detected by the pressure detection means, the maximum frequency (f _max ) of the alternating current input to the motor is calculated and changed by the calculation formula, and the calculation is performed. An operation control method for an inverter-driven compressor , wherein the inverter outputs the highest frequency (f _max ) . A three-phase motor for driving the compressor body, an inverter for changing the frequency of the alternating current input to the three-phase motor, pressure detection means for detecting the discharge side pressure (P _d ) of the compressor body, Control that outputs an alternating current of a predetermined frequency by controlling the inverter so that the discharge side pressure (P _d ) of the compressor body matches a predetermined target pressure (P _t ) based on the detection pressure of the detection means. In an inverter driven compressor equipped with a device,
A maximum value (P _H ) and a minimum value (P _L ) of a range that can be set as the target pressure (P _t ) are set, and
Predetermined correspondence between the change in pressure between the maximum value (P _H ) and the minimum value (P _L ) and the change in frequency that generates the rotational speed at which the motor makes a rated output in response to the change in pressure. Set the calculation formula of the curve approximately expressed within the tolerance of
Based on the discharge side pressure (P _d ) of the compressor main body detected by the pressure detection means, the maximum frequency (f _max ) of the alternating current input to the motor is calculated and changed by the calculation formula, and the calculation is performed. An operation control method for an inverter-driven compressor , wherein the inverter outputs the highest frequency (f _max ) . Said maximum value (P _H), the frequency of the motor rated output at outermost height _{(P H) (f 1)} ,
The minimum value (P _L ), the frequency (f ₃ ) at which the motor is rated output at the minimum value (P _L ), and
An intermediate value (P _M ) between the maximum value (P _H ) and the minimum value (P _L ) and a frequency (f ₂ ) at which the motor is rated output at the intermediate value (P _M ) are obtained, respectively.
Based on the discharge side pressure (P _d ) of the compressor body detected by the pressure detection means,
When the discharge side pressure (P _d ) is equal to or higher than the intermediate value (P _M )

And changing the maximum frequency (f _max ) according to
When the discharge side pressure (P _d ) is less than the intermediate value (P _M )

The operation control method for an inverter-driven compressor according to claim 11, wherein the maximum frequency (f _max ) is changed according to: Said maximum value (P _H), the frequency of the motor rated output at outermost height _{(P H) (f 1)} ,
The minimum value (P _L ) and the frequency (f ₃ ) at which the motor is rated output at the minimum value (P _L ) are obtained,
Based on the discharge side pressure (P _d ) of the compressor body detected by the pressure detection means,

The operation control method for an inverter-driven compressor according to claim 12, wherein the maximum frequency (f _max ) is changed according to: Said maximum value (P _H), the frequency of the motor rated output at outermost height _{(P H) (f 1)} ,
The minimum value (P _L ), the frequency (f ₃ ) at which the motor is rated output at the minimum value (P _L ), and
An intermediate value (P _M ) between the maximum value (P _H ) and the minimum value (P _L ) and a frequency (f ₂ ) at which the motor is rated output at the intermediate value (P _M ) are obtained, respectively.
Based on the discharge side pressure (P _d ) of the compressor body detected by the pressure detection means,

The operation control method for an inverter-driven compressor according to claim 12, wherein the maximum frequency (f _max ) is changed according to: A three-phase motor for driving the compressor body, an inverter for changing the frequency of the alternating current input to the three-phase motor, pressure detection means for detecting the discharge side pressure (P _d ) of the compressor body, Control that outputs an alternating current of a predetermined frequency by controlling the inverter so that the discharge side pressure (P _d ) of the compressor body matches a predetermined target pressure (P _t ) based on the detection pressure of the detection means. In an inverter driven compressor equipped with a device,
The control device is
The maximum value (P _H ) and the minimum value (P _L ) of the settable range are stored as the target pressure (P _t ), and the pressure change between the maximum value (P _H ) and the minimum value (P _L ) Corresponding to the change in pressure and the change in frequency that generates the rotational speed of the motor as a rated output, the approximate relationship can be approximated within a predetermined tolerance by combining a plurality of linear expressions. Storage means for storing the calculation formula expressed in
Based on the discharge side pressure (P _d ) of the compressor body detected by the pressure detection means, the maximum frequency (f _max ) of the alternating current input to the motor is calculated by the calculation formula, and the calculated maximum An inverter-driven compressor comprising a speed control signal output unit that outputs a control signal for causing the inverter to output a frequency. A three-phase motor for driving the compressor body, an inverter for changing the frequency of the alternating current input to the three-phase motor, pressure detection means for detecting the discharge side pressure (P _d ) of the compressor body, Control that outputs an alternating current of a predetermined frequency by controlling the inverter so that the discharge side pressure (P _d ) of the compressor body matches a predetermined target pressure (P _t ) based on the detection pressure of the detection means. In an inverter driven compressor equipped with a device,
The control device is
The maximum value (P _H ) and the minimum value (P _L ) of the settable range are stored as the target pressure (P _t ), and the pressure change between the maximum value (P _H ) and the minimum value (P _L ) And a calculation formula of a curve that approximately represents a correspondence relationship between a change in frequency and a change in frequency that generates a rotational speed that makes the motor a rated output corresponding to the change in pressure within a predetermined allowable error range. Storage means;
Based on the discharge side pressure (P _d ) of the compressor body detected by the pressure detection means, the maximum frequency (f _max ) of the alternating current input to the motor is calculated by the calculation formula, and the calculated maximum An inverter-driven compressor comprising a speed control signal output unit that outputs a control signal for causing the inverter to output a frequency. The storage means of the control device comprises:
Said maximum value (P _H), the frequency of the motor rated output at outermost height _{(P H) (f 1)} ,
The minimum value (P _L ), the frequency (f ₃ ) at which the motor is rated output at the minimum value (P _L ), and
An intermediate value (P _M ) between the highest value (P _H ) and the lowest value (P _L ) and a frequency (f ₂ ) at which the motor is rated output at the intermediate value (P _M ) are stored respectively.
A calculation formula for obtaining the maximum frequency (f _max ) based on the discharge side pressure (P _d ) of the compressor body detected by the pressure detection means, wherein the discharge side pressure (P _d ) is the intermediate value Formula of maximum frequency (f _max ) applied when (P _M ) or more

And a calculation formula for the maximum frequency (f _max ) applied when the discharge side pressure (P _d ) is less than the intermediate value (P _M ).

And remember each
The speed control signal output unit includes an arithmetic processing unit that calculates the maximum frequency (f _max ) by any one of the calculation formulas based on a discharge side pressure (P _d ) of the compressor body. The inverter drive compressor according to claim 16. The storage means of the control device comprises:
Said maximum value (P _H), the frequency of the motor rated output at outermost height _{(P H) (f 1)} ,
The minimum value (P _L ) and the frequency (f ₃ ) at which the motor is rated output at the minimum value (P _L ) are stored respectively.
Based on the discharge side pressure (P _d ) of the compressor body detected by the pressure detection means, a calculation formula for obtaining the maximum frequency (f _max ) is as follows:

And remembering
The said speed control signal output part is provided with the arithmetic processing part which calculates the said highest frequency ( _fmax ) by the said calculation formula based on the discharge side pressure ( _Pd ) of the said compressor main body. The inverter-driven compressor according to 17. The storage means of the control device comprises:
Said maximum value (P _H), the frequency of the motor rated output at outermost height _{(P H) (f 1)} ,
The minimum value (P _L ), the frequency (f ₃ ) at which the motor is rated output at the minimum value (P _L ), and
An intermediate value (P _M ) between the highest value (P _H ) and the lowest value (P _L ) and a frequency (f ₂ ) at which the motor is rated output at the intermediate value (P _M ) are stored respectively.
Formula for determining the maximum frequency (f _max ) based on the discharge side pressure (P _d ) of the compressor body detected by the pressure detection means

And remembering
The said speed control signal output part is provided with the arithmetic processing part which calculates the said highest frequency ( _fmax ) by the said calculation formula based on the discharge side pressure ( _Pd ) of the said compressor main body. The inverter-driven compressor according to 17.

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