JP2009055719A - Air compressor and motor drive control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a rise of a current value of a motor means to not less than a target current value and to control driving of the motor means by considering a rotation state of the motor means when the current value is not more than the target current value. <P>SOLUTION: An air compressor is provided with a compressed air generating means generating compressed air, a tank part storing compressed air generated by the compressed air generating means, the motor means for driving the compressed air generating means, control means 5 and 20 controlling a driving amount of the motor means and a current detecting means 28 detecting a driving current value used for driving the motor means. The control means 5 and 20 control the driving amount of the motor means based on the driving current value detected by the current detecting means 28. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an air compressor and a motor drive control method, and more particularly to an air compressor and a motor drive control method for motor means that can drive motor means to supply compressed air to a building drive tool. .

  When a driving tool such as a nailing machine using compressed air is used at a construction site, it is necessary to install an air compressor that supplies compressed air to the driving tool. The air compressor has a structure in which compressed air is generated in the compressed air generation unit by driving the motor unit, and the generated air is stored in the tank unit to provide compressed air of a predetermined pressure to the driving tool. Yes. Here, the air compressor is provided with a plug for a general outlet (AC power supply), and is supplied with driving power for driving the motor unit by connecting the plug to the outlet (for example, Patent Document 1).

  On the other hand, there are many tools that are used at work sites or the like and need to be supplied with driving power via an outlet, in addition to the air compressor. However, the total amount of power that can be used in each outlet is specified in advance, and a breaker is usually provided to temporarily cut off the power supply to the outlet when the available current value is exceeded. It has been.

When the power is cut off by the breaker, the operation of all the driving tools connected to the same outlet is stopped, so there is a high possibility that the work will be hindered. Therefore, it is necessary to check the usable current value and make sure that the used current values of all the connected driving tools are within the usable current value. Further, in order to surely check the current value, it is necessary to perform current control so that the used current value of each driving device is stably maintained at a current target amount preset for each driving device. .
JP 2006-54941 A (refer to pages 3 to 4 and FIG. 6)

  However, in the process of generating compressed air with an air compressor, the driving load of the motor unit varies depending on the pressure state of the tank unit, etc., so there is a problem that the current value used in the motor unit may also rise and fall. . For this reason, depending on the driving load state of the motor unit, an overshoot phenomenon in which the current value exceeds the target current value may occur, and the current value may temporarily exceed the target current value. .

  On the other hand, if the drive control of the motor unit is performed so that the current value is lower than the target current value, it is difficult to maintain a sufficient number of revolutions in the motor unit, and it is difficult to obtain target output characteristics. There was a problem that it could be.

  The present invention has been made in view of the above problems, and suppresses the current value of the motor means from rising to a target current value or higher. Further, when the current value is equal to or lower than the target current value, the motor means rotates. It is an object of the present invention to provide an air compressor and a motor drive control method capable of performing drive control of motor means in consideration of the state.

  In order to solve the above-described problems, in the motor drive control method according to the present invention, the control means for controlling the drive amount of the motor means is detected by the current detection means for detecting the drive current value used for driving the motor means. The drive amount of the motor means is controlled based on the difference between the drive current value and the desired target current value required for driving the motor means.

  According to the motor drive control method of the present invention, since the control means controls the drive amount of the motor means based on the drive current value detected by the current detection means, the motor means is controlled according to the increase / decrease of the drive current value. Can be controlled. In particular, since the control means controls the drive amount of the motor means based on the current value difference between the drive current value detected by the current detection means and the target current value, the drive current that varies according to the drive of the motor means The value can be controlled to approach the target current value.

  In the motor drive control method described above, the control means detects the drive rotation speed detected by the rotation speed detection means for detecting the drive rotation speed of the motor means, and a desired target rotation speed for driving the motor means. The drive amount of the motor means may be controlled on the basis of the difference in rotational speed.

  In this way, the control means controls the drive amount of the motor means based on the rotational speed difference between the drive rotational speed detected by the rotational speed detection means and the target rotational speed, and thus varies according to the driving of the motor means. Control can be performed so that the drive rotational speed approaches the target rotational speed.

  In particular, when the current value difference between the drive current value and the target current value described above is large, even if the drive control of the motor means is performed based on the rotational speed difference, the drive that rises depending on the drive state of the controlled motor means There is little risk of a sudden increase in current value. For this reason, when the current value difference between the target current value and the drive current value is large, the motor means is controlled based on the rotational speed difference to prevent the drive current value from rising above the target current value. However, it is possible to positively control the drive rotation speed of the motor means, and to perform drive control so that the motor means can sufficiently exhibit performance.

  On the other hand, an air compressor according to the present invention drives compressed air generating means for generating compressed air, a tank section for storing the compressed air generated by the compressed air generating means, and driving the compressed air generating means. Motor means; control means for controlling the drive amount of the motor means; and current detection means for detecting a drive current value used for driving the motor means. The control means is detected by the current detection means. The driving amount of the motor means is controlled based on the driving current value.

  According to the air compressor of the present invention, the control means controls the drive amount of the motor means based on the drive current value detected by the current detection means, so the motor means is controlled according to the increase / decrease of the drive current value. be able to. For this reason, when the drive current value is high, the drive amount of the motor means can be reduced by reducing the drive amount of the motor means. When the drive current value is low, the drive amount of the motor means is increased. As a result, the drive current value can be increased.

  Further, the control means classifies the drive state of the motor means based on the drive current value detected by the current detection means, and calculates a coefficient used for calculating the drive amount based on the classified drive state. It may be changed.

  In this way, by classifying the driving state of the motor means based on the detected driving current value and changing the coefficient based on the classified driving state, the driving current is increased by increasing the coefficient in one driving state. Calculate / determine the drive amount of the motor means so that the increase / decrease in the value is large, and calculate / determine the drive amount of the motor means so that the increase / decrease in the drive current value is small by reducing the coefficient in other drive states. be able to. For this reason, the drive amount can be appropriately changed according to the detected drive current value, and the drive control of the motor means can be flexibly adjusted according to the drive current value.

  Further, the control means uses the desired target current value required for driving the motor means as a reference, the current value difference between the drive current value detected by the current detection means and the target current value, and the coefficient. Based on this, the drive amount may be calculated.

  Thus, the control means calculates the drive amount based on the current value difference between the drive current value detected by the current detection means and the target current value in addition to the above-described coefficient, so that the current value difference is reduced. When the difference is large, the drive amount of the motor means is increased, and the drive control of the motor means is positively performed. When the current value difference is small, the drive amount of the motor means is decreased and the drive control of the motor means is finer. Can be performed. For this reason, it becomes possible to control the drive current value that fluctuates according to the driving of the motor means so as to approach the target current value, and the overshoot that causes the drive current value to fluctuate to a higher current value than the target current value. The phenomenon can be effectively suppressed.

  Further, the air compressor described above has a rotation speed detection means for detecting the drive rotation speed of the motor means, and the control means detects the rotation speed based on a desired target rotation speed in driving the motor means. The drive amount may be calculated based on the difference between the rotational speed detected by the means and the target rotational speed and the coefficient.

  Thus, in addition to the above-described coefficient, the control means calculates the drive amount based on the rotational speed difference between the drive rotational speed detected by the rotational speed detection means and the target rotational speed, so that the rotational speed difference is large. In this case, the drive amount of the motor means is increased and the drive control of the motor means is positively performed. When the difference in rotational speed is small, the drive amount of the motor means is decreased and the drive control of the motor means is more finely controlled. Can be done. For this reason, it becomes possible to control so that the drive rotation speed which fluctuates according to the drive of the motor means approaches the target rotation speed.

  In particular, when the current value difference between the drive current value and the target current value described above is large, even if the drive amount is calculated based on the rotation speed difference and the drive control of the motor means is performed, There is little possibility that the drive current value that rises depending on the drive state rises rapidly. For this reason, when the current value difference between the target current value and the drive current value is large, the drive current value is larger than the target current value by performing control by calculating the drive amount of the motor means based on the rotation speed difference. In addition, it is possible to positively control the drive rotation speed of the motor means while preventing the motor means from rising, and it is possible to perform drive control so that the motor means can exhibit its performance sufficiently.

  According to the motor drive control method of the present invention, since the control means controls the drive amount of the motor means based on the drive current value detected by the current detection means, the motor means is controlled according to the increase / decrease of the drive current value. Can be controlled. In particular, since the control means controls the drive amount of the motor means based on the current value difference between the drive current value detected by the current detection means and the target current value, the drive current that varies according to the drive of the motor means The value can be controlled to approach the target current value.

  Further, according to the air compressor of the present invention, since the drive amount of the motor means is controlled based on the drive current value detected by the current detection means, the motor means is controlled according to increase / decrease of the drive current value. Can do. For this reason, the motor means can be controlled in accordance with the drive current value so that the drive current value does not rise above a predetermined current value (target current value). Can be suppressed.

  Hereinafter, an air compressor according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a schematic configuration of an air compressor. The air compressor 1 is roughly configured by a tank unit 2, a compressed air generation unit (compressed air generation unit) 3, a motor unit (motor unit) 4, and a control circuit unit (control unit) 5.

  The tank unit 2 has a storage tank 8 for storing compressed air. The storage tank 8 stores the compressed air having a constant pressure generated by the compressed air generator 3 and is usually maintained at a pressure of about 3.5 MPa to 4.3 MPa.

  The storage tank 8 is provided with a plurality of compressed air outlets 9. In the present embodiment, a high-pressure outlet 9a for taking out high-pressure compressed air and a normal-pressure outlet 9b for taking out normal-pressure compressed air are provided. Each of the outlets 9a and 9b is provided with pressure reducing valves 10a and 10b for reducing the compressed air obtained from the respective outlets 9a and 9b to a desired pressure. In the high pressure outlet 9a, the pressure reducing valve 10a is provided. The pressure of the compressed air taken out is reduced to about 1.5 MPa to 2.50 MPa, and the pressure of the compressed air taken out by the pressure reducing valve 10b is reduced to about 0.7 MPa to 1.5 MPa at the normal pressure outlet 9b. .

  Since the compressed air in the storage tank 8 is normally maintained at a pressure of about 3.5 MPa to 4.3 MPa as described above, the compressed air taken out from the high pressure outlet 9a and also taken out from the normal pressure outlet 9b is used. In addition, the desired pressure described above can be maintained by the pressure reducing valves 10a and 10b. In addition, an air hose (not shown) can be attached to and detached from each of the outlets 9a and 9b in order to supply the compressed air decompressed by the pressure reducing valves 10a and 10b to a driving tool such as a nail driver. Yes.

  The compressed air generating unit 3 has a structure that generates compressed air by reciprocating a piston provided in the cylinder and compressing air drawn into the cylinder from the intake valve of the cylinder. The compressed air is supplied to the storage tank 8 of the tank unit 2 through the connection pipe 14.

  The motor unit 4 has a role of generating a driving force for reciprocating the piston of the compressed air generating unit 3. The motor unit 4 is provided with a stator 16 and a rotor 17 for generating a driving force. The stator 16 is formed with U-phase, V-phase, and W-phase windings 16a, 16b, and 16c, and a rotating magnetic field is formed by passing a current through the windings 16a to 16c.

  The rotor 17 is composed of a permanent magnet, and the rotor 17 is rotated by a rotating magnetic field formed by a current flowing through the windings 16a, 16b, and 16c of the stator 16. The motor unit 4 is provided with a rotation number detection unit (rotation number detection means) 18 for detecting the rotation of the rotor 17. The rotation speed detection unit 18 is provided with a Hall IC, and the rotation speed of the rotor 17 is detected by detecting a change in the magnetic field in the rotor 17 using the Hall IC.

  As shown in FIG. 2, the control circuit unit 5 is roughly configured by a microprocessor (MPU: Micro Processing Unit, control means) 20, a converter circuit 21, and an inverter circuit 22.

  The converter circuit 21 is roughly configured by a rectifier circuit 24, a booster circuit 25, and a smoothing circuit 26, and so-called PAM (Pulse Amplitude Modulation) control is executed by the converter circuit 21. Here, the PAM control is a method of controlling the rotation speed of the motor unit 4 by changing the pulse height of the output voltage by the converter circuit 21. On the other hand, the inverter circuit 22 performs so-called PWM (Pulse Width Modulation) control. The PWM control is a method for controlling the rotation speed of the motor unit 4 by changing the pulse width of the output voltage.

  Compared with PWM control, PAM control has a characteristic that the motor unit 4 is less susceptible to lowering efficiency at low rotation and can cope with high rotation by increasing the voltage. It is a control method mainly used during operation and steady operation. On the other hand, the PWM control is a control method mainly used at the time of start-up or voltage drop. The microprocessor 20 executes control by suitably switching between PAM control by the converter circuit 21 and PWM control by the inverter circuit 22 according to the operating state of the air compressor 1.

  The rectifier circuit 24 and the smoothing circuit 26 of the converter circuit 21 have a role of converting into an AC voltage by rectifying and smoothing an AC power source 29 serving as a drive source of the air compressor 1. A switching element 25 a is provided inside the booster circuit 25, and has a role of controlling the amplitude of the DC voltage in accordance with a control command from the microprocessor 20. The booster circuit 25 is controlled via a booster controller 27 that has received a PAM command from the microprocessor 20.

  A current detection unit (current detection means) 28 is provided between the rectifier circuit 24 and the booster circuit 25 of the converter circuit 21. The current value detected by the current detection unit 28 is output to the microprocessor 20.

  The inverter circuit 22 has a function of converting the DC voltage pulse converted by the converter circuit 21 into positive and negative at regular intervals and converting the DC voltage into an AC voltage having a pseudo sine wave by converting the pulse width. is doing. By adjusting the pulse width, it is possible to control the rotational speed of the motor unit 4 as described above. The microprocessor 20 controls the inverter circuit 22 by adjusting the operation amount (control amount) of the motor unit 4.

  The microprocessor 20 is a control means for stabilizing the pressure of the compressed air in the tank unit 2 to 3.5 MPa to 4.0 MPa by performing drive control of the converter circuit 21 and the inverter circuit 22. The microprocessor 20 includes a central processing unit (CPU), a RAM (Random Access Memory) used as a temporary storage area such as a work memory, and a control processing program (see FIG. 4 described later, motor drive according to the present invention). ROM (Read that shows a control method), area information classified by drive current value (see FIG. 3A), operation amount calculation method information (see FIG. 3B), etc. A function such as “Only Memory” is realized by a one-chip LSI.

  The microprocessor 20 is input with the rotational speed information (information about the driving rotational speed) of the motor unit 4 (more specifically, the rotor 17) detected by the rotational speed detection unit 18 and is detected by the current detection unit 28. Current value information (drive current value information) is input. On the other hand, the microprocessor 20 is configured to be able to output control information (PAM instruction, PWM instruction) to the converter circuit 21 and the inverter circuit 22. In the converter circuit 21 and the inverter circuit 22, drive control of the motor unit 4 is executed based on the control information output by the microprocessor 20.

  The microprocessor 20 outputs a PAM command to the boost controller 27, thereby controlling the switching element 25 a of the boost circuit 25 via the boost controller 27 to control the drive of the converter circuit 21. Similarly, the microprocessor 20 controls the inverter circuit 22 by outputting a PWM command to the inverter circuit 22.

  However, as described above, the PAM control is a control method that is mainly used at the time of high output and steady operation, and the PWM control is a control method that is mainly used at the time of start-up or voltage drop. For this reason, when the air compressor 1 is started, the microprocessor 20 smoothly increases the duty value of the inverter circuit 22 from 20% to 100% so that the air compressor 1 (motor unit 4) is smoothly driven. When the output voltage of the inverter circuit 22 reaches a predetermined voltage value (for example, 200 V) or when the rotation speed of the motor unit 4 reaches a predetermined rotation speed (for example, 3000 rpm), the duty of PWM control is increased. With the value fixed at 100%, a PAM command is output to the converter circuit 21 to perform drive control of the motor unit 4 by PAM control.

  In the microprocessor 20, when performing PAM control or PWM control, a converter circuit based on the drive current value detected by the current detection unit 28 and the drive rotation speed of the motor unit 4 detected by the rotation speed detection unit 18. 21 and the operation amount of the inverter circuit 22 are determined.

  FIG. 3A is a diagram showing a target current value and regions A to D divided into regions based on the target current value. Here, the target current value indicates a design drive current value that can be used in a state where the air compressor 1 according to the present embodiment is normally used. For example, when the target current value is 14.5 A, the drive power is maintained at about 14.5 A when the air compressor is normally used. Based on the target current value of each drive tool, the user connects the drive tool to the outlet considering that the total power amount of each drive tool to be connected to the outlet is within the allowable power range of the outlet. .

  However, since the value of the driving power amount may vary depending on the driving load state of the driving tool, for example, the allowable power amount of the outlet is exceeded with a temporary increase in the driving power amount of the driving tool. There may be cases. In such a case, a large load may be applied to the outlet, so if the power consumption exceeds the allowable power consumption of the outlet, the power supply is intentionally cut off. A breaker is generally provided.

  For this reason, when performing drive control of the air compressor 1, it is preferable to drive-control so that a drive current value may be 14.5 A or less which is a target current value. On the other hand, if the drive control of the motor unit 4 is always performed with a lower drive current value so that the drive current value does not exceed the target current value, it becomes difficult to obtain desired drive characteristics in the motor unit 4. There has been a problem that the capability of the motor unit 4 may not be fully exhibited.

  Therefore, in the air compressor 1 according to the present embodiment, as shown in FIG. 3A, the drive state of the motor unit 4 is changed to the region A (the number of revolutions) based on the drive current value detected by the current detection unit 28. Control region), region B (current + rotation speed control mode), region C (current fine adjustment mode), region D (current reduction mode), and which region the microprocessor 20 has at regular intervals. It is determined whether the driving state of the motor unit 4 is applicable. Then, the microprocessor 20 calculates an operation amount (drive amount) according to the calculation formula of the list shown in FIG. 3B based on the determined drive state, and sends it to the converter circuit 21 and the inverter circuit 22. A process of outputting an operation command (PAM command, PWM command) is executed.

  A specific control process (motor drive control method) of the microprocessor 20 will be described with reference to a flowchart shown in FIG.

  The microprocessor 20 detects the drive current value from the current detection unit 28 at regular intervals (step S100), and then detects the drive rotation number of the motor from the rotation number detection unit 18 (step S110). Subsequently, the microprocessor 20 determines whether or not the detected drive current value is 13 A or less (step S120).

  When the detected drive current value is 13 A or less (Yes in step S120), the microprocessor 20 determines that the driving state of the motor unit 4 corresponds to the region A, and the region A shown in FIG. The manipulated variable is calculated based on the formula (step S130). In this calculation formula, the target rotational speed is the rotational speed of the motor unit 4 required to maintain the pressure value in the storage tank 8 at a constant pressure value (for example, 3.5 MPa to 4.0 MPa) ( For example, 3000 rpm), and the drive rotational speed means the rotational speed of the motor unit 4 detected by the rotational speed detection unit 18.

  The gain is a coefficient used for calculating the operation amount (drive amount), and a different gain is set in advance for each of the regions A to D. For example, the relationship between the gain Ga1 in the region A and the gain Ga2 in the region B in which the control amount is calculated based on the rotational speed difference between the target rotational speed and the drive rotational speed of the motor unit 4 is defined by “Ga1> Ga2”. ing.

  The reason why the gain Ga1 in the region A is larger than the gain in the region 2 is that the drive current value in the region A is 13 A or less, so that the operation amount of the motor unit 4 is increased by using the gain Ga1 having a large value. This is because the drive current value is less likely to rise far beyond the target current value even if it is increased. On the other hand, in the case of the region B, since the current value difference between the drive current value detected by the current detection unit 28 and the target current value is small, the gain Ga2 is set to a large value and the operation amount of the motor unit 4 is increased. If it is increased, the drive current value may exceed the target current value. For this reason, the value of the gain Ga2 is set to a value smaller than the gain Ga1 of the region A.

  The microprocessor 20 calculates the operation amount by adding the gain Ga1 to the rotation speed difference between the target rotation speed and the drive rotation speed detected by the rotation speed detector 18. In the region A, since the current value difference between the target current value and the drive current value is large, the motor unit 4 is more controlled than the control process of the motor unit 4 based on the current value difference (operation amount calculation process based on the current value difference). The control processing of the motor unit 4 based on the rotational speed difference (operation amount calculation processing based on the rotational speed difference) is performed with priority given to the fact that the above function can be sufficiently exerted.

  After calculating the operation amount in the region A (step S130), the microprocessor 20 outputs a control command (PAM command or PWM command) to the converter circuit 21 or the inverter circuit 22 based on the calculated operation amount (step S140). To do.

  In the converter circuit 21 that has received the PAM command or the inverter circuit 22 that has received the PWM command, the motor unit 4 is rotationally driven based on the operation amount calculated in step S130 in accordance with the received control command (PAM command, PWM command). Let In the start-up operation of the air compressor 1, the PWM control by the inverter circuit 22 is often performed as described above. When the drive of the air compressor 1 is in the steady operation state, the PAM control by the converter circuit 21 is performed. There are many.

  When the microprocessor 20 outputs a PAM command to the converter circuit 21, the boost controller 27 controls the switching element 25 a of the boost circuit 25. Here, when the boost controller 27 has a structure in which the content (operation amount) of the output value of the PAM command is determined from the value of the voltage value, the PAM is output according to the value of the voltage value output by the microprocessor 20. Command operation amount information is transmitted. For example, when a PAM command of 5V can be sent from the microprocessor 20 to the boost controller 27, when the duty of the output voltage is 35%, that is, 5V × 0.35 = 1.75V as a reference. As a result, the operation amount is transmitted. In the step-up controller 27, based on the voltage value of the transmitted PAM command, when the duty value of the voltage value is higher than 35% (when the voltage value is larger than 1.75 V), the switching element 25a Is controlled to increase the voltage value of the electric power supplied to the motor unit 4, and when the duty value of the voltage value is lower than 35% (when the voltage value is smaller than 1.75V), the motor The voltage value supplied to the unit 4 is decreased. As described above, the boost controller 27 controls the switching element 25a according to the magnitude of the voltage value to perform the voltage boosting process and control the drive of the motor unit 4.

  Thereafter, the microprocessor 20 repeatedly executes the process shown in FIG. 4 at regular time intervals.

  On the other hand, if the detected current value is not 13 A or less (in the case of No in step S120), the microprocessor 20 determines that the detected drive current value is 14 A or less, and further the target rotational speed of the motor unit 4 It is determined whether the rotational speed difference from the rotational speed detected by the rotational speed detector 18 is other than ± 50 rpm (not included in −50 rpm to +50 rpm) (step S150). When the detected drive current value is 14 A or less and the rotational speed difference of the motor unit 4 is other than ± 50 rpm (Yes in step S150), the microprocessor 20 indicates that the drive state of the motor unit 4 is a region. The operation amount is calculated based on the calculation formula used in the region B shown in FIG. 3B in the case where the rotation speed difference of the motor unit 4 is other than ± 50 rpm (step S160).

  When the current value is larger than 13A and not larger than 14A and the rotational speed difference of the motor unit 4 is other than ± 50 rpm, the microprocessor 20 performs the target rotational speed and rotational speed in order to perform the rotational speed increasing process quickly. The operation amount is calculated based on the rotational speed difference from the drive rotational speed detected by the number detection unit 18. However, as described above, the value of the gain Ga2 is smaller than the gain Ga1 of the region A. Therefore, even if the rotational speed difference is the same as that in the region A, the calculated operation amount is The value is smaller than the case.

  After calculating the operation amount in the region B (step S160), the microprocessor 20 outputs a control command (PAM command or PWM command) to the converter circuit 21 or the inverter circuit 22 based on the calculated operation amount (step S140). ). In response to the control command, the converter circuit 21 or the inverter circuit 22 rotates the motor unit 4 based on the operation amount calculated in step S160 according to the received control command (PAM command, PWM command). Thereafter, the microprocessor 20 repeatedly executes the process shown in FIG. 4 at regular time intervals.

  In the process of step S150, “the detected current value is 14 A or less, and the difference between the target rotational speed of the motor unit and the driving rotational speed detected by the rotational speed detecting unit 18 is other than ± 50 rpm”. If the condition is not satisfied (in the case of No in step S150), the microprocessor 20 has a detected current value of 14 A or less, and is further detected by the target rotation speed and the rotation speed detection section 18 of the motor section 4. It is determined whether or not the difference from the drive rotational speed is within ± 50 rpm (step S170).

  When the detected current value is 14 A or less and the rotational speed difference of the motor unit 4 is within ± 50 rpm (Yes in step S170), the microprocessor 20 indicates that the driving state of the motor unit 4 is in the region. The operation amount is calculated based on the calculation formula used when the difference in the rotation speed of the motor unit 4 is within ± 50 rpm in the region B shown in FIG. 3B (step S180). ).

  In the region B, when the rotational speed difference of the motor unit 4 is within ± 50 rpm, as shown in FIG. 3B, the target current value and the drive current value detected by the current detection unit 28 The operation amount is calculated based on the current value difference.

  In the present embodiment, as described above, 14.5 A is set as the target current value. However, even when the target current value is set in advance, the pressure of the compressed air in the storage tank 8 is high, etc. As described above, when a driving load heavier than usual is imposed when the motor unit 4 is driven, the current value during driving of the air compressor 1 may exceed the target current value. Therefore, the microprocessor 20 differs from the operation amount calculation process in step S160 described above when the current value is 14 A or less and the rotational speed difference of the motor unit 4 is within ± 50 rpm. The amount of operation is calculated by adding the gain Gb1 to the current difference between the drive current value detected by the current detection unit 28 and the drive current value.

  Note that the gain used when calculating the operation amount based on the current value difference is also a value set in advance for each region. For example, as shown in FIG. 3B, the gain in the region C is defined as the gain Gb2, and the gain in the region D is defined as the gain Gb3.

  The relationship among the gain Gb1 in the region B, the gain Gb2 in the region C, and the gain Gb3 in the region D is defined by “Gb3> Gb1> Gb2.” The reason why the gain Gb2 in the region C shows the smallest value is that the target current value is located in the region C, and the operation amount adjustment in this region C is preferably a minute adjustment. It is set to a value smaller than the gain (Gb1, Gb3) of the area. On the other hand, in the region D, the drive current value is larger than the target current value. Therefore, the gain Gb3 value is larger than the other gains (Gb1, Gb2) in order to quickly reduce the drive current value. Is set to

  After calculating the operation amount in the region B (step S180), the microprocessor 20 outputs a control command (PAM command or PWM command) to the converter circuit 21 or the inverter circuit 22 based on the calculated operation amount (step S140). ). In response to the control command, the converter circuit 21 or the inverter circuit 22 rotates the motor unit 4 based on the operation amount calculated in step S180 in accordance with the received control command (PAM command, PWM command). Thereafter, the microprocessor 20 repeatedly executes the process shown in FIG. 4 at regular time intervals.

  If the detected current value is not 14 A or less (No in Step S150 and Step S170), the microprocessor 20 determines whether the detected drive current value is greater than 14 A and is further 15 A or less. It is determined whether or not (step S190). When the detected current value is larger than 14A and 15A or less, the microprocessor 20 determines that the driving state of the motor unit 4 corresponds to the region C, and uses the calculation formula of the region C shown in FIG. Based on this, an operation amount is calculated (step S200). Since the gain Gb2 is a small value as described above, the manipulated variable calculated by the calculation formula of the region C is a small value.

  Then, after calculating the operation amount in the region C (step S200), the microprocessor 20 outputs a control command (PAM command or PWM command) to the converter circuit 21 or the inverter circuit 22 based on the calculated operation amount (step S200). Step S140). In response to the control command, the converter circuit 21 or the inverter circuit 22 rotates the motor unit 4 based on the operation amount calculated in step S200 in accordance with the received control command (PAM command, PWM command).

  Since the operation amount in the region C is a small value, even when the drive current value that varies depending on the operation amount is detected by the current detection unit 28, the current is slightly smaller than the drive current value detected immediately before. The value will fluctuate. As a result, it becomes possible to finely adjust the drive current value of the motor unit 4 and to stably bring the drive current value close to the target current value. Thereafter, the microprocessor 20 repeatedly executes the process shown in FIG. 4 at regular time intervals.

  On the other hand, if the detected drive current value is not greater than 14A and not less than 15A (No in step S190), the microprocessor 20 determines whether or not the detected current value is greater than 15A. Is determined (step S210). When the detected current value is larger than 15 A, the microprocessor 20 determines that the driving state of the motor unit 4 corresponds to the region D, and calculates the operation amount based on the calculation formula of the region D shown in FIG. (Step S220). As described above, since the gain Gb3 is set to a larger value than the gain Gb1 and the gain Gb2, the absolute value of the calculated operation amount is a large value for the operation amount calculated by the calculation formula of the region D. Further, as apparent from FIG. 3A, in region D, the drive current value is larger than the target current value, and therefore the value calculated by (target current value−drive current value) is negative. The operation amount becomes a negative value.

  For this reason, the operation amount calculated in the region D is larger than the operation amount calculated based on the current value difference calculated in the other regions B and C, and the operation amount is reduced in the direction in which the operation amount is reduced. Is calculated. Accordingly, the microprocessor 20 receives the control command by outputting the control command (PAM command or PWM command) to the converter circuit 21 or the inverter circuit 22 (step S140) based on the operation amount calculated in the region D. The converter circuit 21 or the inverter circuit 22 performs control for reducing the drive amount of the motor unit 4. By reducing the drive amount of the motor unit 4 in this manner, the increased drive current value can be reduced so as to approach the target current value. Thereafter, the microprocessor 20 repeatedly executes the process shown in FIG. 4 at regular time intervals.

  On the other hand, if the current value is greater than 15A (No in step S210), it is determined that the current value detected by current detector 28 is abnormal. In this case, the microprocessor 20 stops the driving of the motor unit 4 and performs error notification (error processing) using a sound, a warning lamp, or the like as necessary (step S230).

  As described above, in the air compressor 1 according to the present invention, the microprocessor 20 of the control circuit unit 5 controls the operation amount of the motor unit 4 based on the drive current value detected by the current detection unit 28. The drive operation of the motor unit 4 can be performed so that the value approaches the target current value.

  In particular, in this embodiment, when a certain condition is satisfied such as when the detected current value is equal to or less than a predetermined current value (in this embodiment, (1) when the detected current value is 13 A or less. (2) When the detected current value is 14 A or less and the rotational speed difference of the motor unit 4 is other than ± 50 rpm), the driving rotational speed of the motor unit 4 is brought closer to the target rotational speed. Since the operation amount is calculated based on the rotation speed difference of the motor unit 4 with priority given to correction, the motor unit 4 can be operated more quickly and effectively than when the operation amount is calculated based on the current value difference. The rotational speed can be brought close to the target rotational speed.

  On the other hand, when a certain condition is satisfied such as when the detected drive current value is equal to or greater than a predetermined current value (in this embodiment, (1) when the detected current value is equal to or greater than 14A, and (2) When the detected current value is greater than 13A and less than or equal to 14A and the rotational speed difference of the motor unit 4 is within ± 50 rpm), unlike the above, the detected drive current value is set to the target current value. Since the operation amount is calculated by performing correction so that the operation amount is closer to that of the motor unit 4, it is possible to perform finer adjustments than when the operation amount is calculated based on the difference in the number of revolutions of the motor unit 4, and the current value is given the highest priority. The drive amount of the motor unit 4 can be controlled.

  Furthermore, in the air compressor 1 according to the present embodiment, when calculating the operation amount based on the rotation speed difference of the motor unit 4, the gain Ga1 used for calculating the operation amount when the detected current value is 13 A or less. Is set to a value larger than the value of the gain Ga2 used for calculating the manipulated variable when the detected current value is larger than 13A. For this reason, when the detected current value is a relatively low current value (13 A or less) than the target current value of 14.5 A, the drive control of the motor unit 4 can be actively performed, When the detected current value is a current value that is relatively close to the target current value (current value greater than 13 A), the drive control of the motor unit 4 is finely performed by reducing the operation amount of the motor unit 4. Can do.

  Similarly, when calculating the operation amount based on the current value difference, the value of the gain Gb1 used for calculating the operation amount is detected when the detected current value is larger than 13A and 14A or less. The current value difference between the detected drive current value and the target current value is set to a value larger than the value of the gain Gb2 used for calculating the manipulated variable when the measured current value is greater than 14A and 15A or less. Is relatively large (when the detected current value is larger than 13A and equal to or smaller than 14A), the drive control of the motor unit 4 can be actively performed. When the detected current value is a current value that is relatively close to the target current value of 14.5 A (when the current value is greater than 14 A and less than 15 A), the operation amount of the motor unit 4 is reduced. By reducing it, the drive control of the motor part 4 can be performed finely.

  Furthermore, when the detected current value is larger than 15 A, the value of the gain Gb3 used for calculating the manipulated variable is set to a value larger than the gain Gb1 and the gain Gb2, thereby increasing the calculated manipulated variable value. Thus, the drive amount of the motor unit 4 can be controlled so that the detected drive current value is reduced to the target current value.

  As described above, in the air compressor 1 according to the present invention, when there is a margin in the drive current value until the target current value is reached, the drive control of the motor unit 4 is positively performed based on the rotational speed difference. Thus, drive control can be positively performed so that the performance of the motor unit 4 can be exhibited. When the drive current value is close to the target current value, the drive current value is changed to the target current value as the motor unit 4 is driven by controlling the drive of the motor unit 4 based on the current value difference. It is possible to perform control with the highest priority being not to exceed. Further, when the drive current value exceeds the target current value, the drive current value is set to the target value by performing drive control of the motor unit 4 so that the drive current value is lower than the target current value. Active control can be performed so as to reduce the current value.

  The air compressor and motor drive control method according to the present invention have been described in detail with reference to the drawings. However, the air compressor and motor drive control method according to the present invention are not limited to those described above. . It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention.

  For example, in the air compressor 1 according to the above-described embodiment, the case has been described in which the microprocessor 20 divides the driving state of the motor unit 4 into the four regions A to D based on the driving current value. The area division by the microprocessor 20 is not limited to the four areas described above. For example, the microprocessor 20 may be configured to divide the area into three areas or less, or may be configured to divide the area into five areas or more.

  Further, in the above-described embodiment, the detected current value is 13 A or less in the region A, the region B is greater than 13 A and 14 A or less, the region B, the region greater than 14 A is 15 A or less in the region C, and the region D is greater than 15 A. However, the current value used as a reference for the area division is not limited to these values, and can be appropriately changed according to the performance and characteristics of the motor unit 4.

  Furthermore, in the region B, a case has been described in which different operation amount calculation methods are used depending on whether the difference between the target rotational speed of the motor unit 4 and the driving rotational speed is within ± 50 rpm or other than ± 50 rpm. The difference in the driving rotational speed is not necessarily limited to ± 50 rpm, and the calculation method may be changed based on the rotational speed difference other than ± 50 rpm.

  In the above-described embodiment, the case where the motor drive control method according to the present invention is used for the air compressor 1 has been described. However, the motor drive control method according to the present invention is not necessarily limited to the motor unit of the air compressor 1. However, the present invention is not limited to drive control No. 4, and can be used for drive control of motor means in other products.

It is a block diagram which shows schematic structure of the air compressor which concerns on embodiment. It is a block diagram which shows the control circuit part of the air compressor which concerns on embodiment. (A) is the figure which showed the area | region A-the area | region D divided based on the detected drive current value, (b) is the calculation formula of the operation amount calculated based on the area | region A-the area | region D. The list is shown. It is the flowchart which showed the processing content (motor drive control method) of the microprocessor which concerns on embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Air compressor 2 ... Tank part 3 ... Compressed air production | generation part (compressed air production | generation means)
4 ... Motor part (motor means)
5 ... Control circuit section (control means)
8 ... Reservoir tank 9 (of tank part) ... Compressed air outlet 9a ... High pressure outlet 9b (of compressed air outlet) ... Normal pressure outlet 10a, 10b (of compressed air outlet) ... Pressure reducing valve 14 ... Connection pipe 16 (stator) 16a, 16b, 16c (winding of stator) 17 ... rotor 18 (rotation speed detection means) (rotation speed detection means)
20: Microprocessor (control means)
DESCRIPTION OF SYMBOLS 21 ... Converter circuit 22 ... Inverter circuit 24 ... (Converter circuit) Rectifier circuit 25 ... (Converter circuit) Boost circuit 25a ... (Boost circuit) Switching element 26 ... (Converter circuit) Smoothing circuit 27 ... Boost controller 28 ... Current detection unit (current detection means)
29… AC power supply

Claims (6)

Control means for controlling the drive amount of the motor means,
Based on the current value difference between the drive current value detected by the current detection means for detecting the drive current value used for driving the motor means and the desired target current value required for driving the motor means, the motor means The motor drive control method characterized by controlling the drive amount of. The control means includes
Based on the rotational speed difference between the rotational speed detected by the rotational speed detection means for detecting the rotational speed of the motor means and the desired target rotational speed for driving the motor means, the drive amount of the motor means is determined. The motor drive control method according to claim 1, wherein control is performed. Compressed air generating means for generating compressed air;
A tank section for storing the compressed air generated by the compressed air generating means;
Motor means for driving the compressed air generating means;
Control means for controlling the drive amount of the motor means; current detection means for detecting a drive current value used for driving the motor means;
Have
The air compressor according to claim 1, wherein the control means controls a drive amount of the motor means based on a drive current value detected by the current detection means. The control unit classifies the driving state of the motor unit based on the current value detected by the current detection unit, and changes a coefficient used to calculate the driving amount based on the classified driving state. The air compressor according to claim 3. The control means is based on a current value difference between the drive current value detected by the current detection means and the target current value based on a desired target current value required for driving the motor means and the coefficient. The air compressor according to claim 4, wherein the driving amount is calculated. Having rotation speed detection means for detecting the drive rotation speed of the motor means;
The control means is based on a difference in rotational speed between the drive rotational speed detected by the rotational speed detection means and the target rotational speed and the coefficient based on a desired target rotational speed in driving the motor means. The air compressor according to claim 4, wherein the driving amount is calculated.

Images