JP2004320915A - Controller for reciprocating pump and reciprocating pump applying the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for reciprocating pump which can perform highly accurate fluid discharge control even if an induction motor is enlarged, and which can achieve it with a simple constitution, and a reciprocating pump to which the controller is applied. <P>SOLUTION: DC braking is performed by performing a half-wave rectification control to only a single phase (the U phase) of the induction motor 2 in the phase control during braking. In addition to it, a triac Q5 interposed in series to a freewheel diode D2 is turned on. By this, a current generated by power generating functions of the induction motor 2 is short-circuited and refluxed by the freewheel diode D2 interposed in parallel to the induction motor 2 during the period of not executing the DC braking. The generated current is discharged. That is to say, the current is refluxed by a circuit including the two phases (the U phase, the V phase) in the three-phase induction motor 2 and the freewheel diode D2 (the remaining one phase (the W phase) is stopped as control operation). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a control device for a reciprocating pump for controlling a reciprocating pump for performing a pump operation by reciprocating an operating unit such as a diaphragm, a plunger, and a bellows based on driving of an induction motor connected to an AC power supply, and It relates to a reciprocating pump to which it is applied.
[0002]
[Prior art]
Conventionally, a reciprocating pump drives an induction motor such as a three-phase motor with electric power from an AC power supply such as a three-phase motor, and transmits a driving force of the induction motor to an operating unit such as a diaphragm, whereby the operating unit is pushed out and a predetermined amount of the driving force is pushed out. Discharge the fluid. When returning the operating portion to the original position, the power supply to the induction motor is stopped, and the pump load due to the reaction force against the discharge side pressure and the elasticity of the return spring or the like urged to return the operating portion to the original position. The negative force of the body is used (see Patent Document 1).
[0003]
Here, when the rotor of the induction motor is increased in size to increase the starting force in order to perform fluid discharge control with higher accuracy, it is necessary to increase the braking force. At this time, as a method of increasing the braking force, it is possible to respond by increasing the elastic force of the return spring.
[0004]
[Patent Document 1]
JP-A-5-126052
[0005]
[Problems to be solved by the invention]
However, when the elastic force of the return spring is increased, the return spring has a biasing force in a direction opposite to the moving direction of the operating portion driven by the induction motor, and thus there is a problem that the required starting torque of the induction motor increases. When the starting torque of the induction motor increases, the inertia also increases, and high-precision control cannot be achieved. In addition, increasing the elastic force of the return spring sometimes causes breakage of the return spring due to driving of the induction motor.
[0006]
Further, the induction motor needs to be intermittently driven each time the discharge operation of the reciprocating pump is performed, so that a large starting current flows each time, and the heat generation of the induction motor tends to increase.
[0007]
On the other hand, a method of electrically braking the induction motor is also conceivable, but a circuit of another system may be required to perform the braking, and the configuration is complicated. In addition, a method of controlling the induction motor using an inverter is also conceivable, but also in this case, the circuit configuration is complicated, and in addition, the device is often large and expensive, so that control of the reciprocating pump is difficult. In some cases it was difficult to apply.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the related art, and it is possible to perform high-precision fluid discharge control even when the size of an induction motor is increased, but to achieve a reciprocating motion that can be achieved with a simple configuration. An object of the present invention is to provide a pump control device and a reciprocating pump to which the control device is applied.
[0009]
[Means for Solving the Problems]
The control device for a reciprocating pump according to the present invention is applied to a reciprocating pump for reciprocating an operating unit for discharging a fluid by driving an induction motor connected to an AC power supply, for controlling the reciprocating pump. A control device for a reciprocating pump, comprising: a triac interposed between the AC power supply and the induction motor; and a freewheel diode interposed in parallel with the induction motor. The phase control of the triac is performed at the time of starting, and the phase control is performed so that the triac is controlled to a single-phase half-wave at the time of braking of the induction motor, and the current is returned to the induction motor and the freewheel diode.
[0010]
In the control device for a reciprocating pump according to the present invention, a triac (also called a bidirectional thyristor) is interposed between the AC power supply and the induction motor. A triac is a semiconductor element that can be switched by one gate regardless of the polarity of a voltage. Like a thyristor, a triac is turned on when a current flows through the gate. However, once turned on, the triac does not turn off even if the gate current becomes zero. Must be zero. Since the reciprocating pump according to the present invention uses an AC power supply, it crosses zero (current becomes 0) in a half cycle and is turned off. Therefore, the phase is controlled by controlling the start signal based on the gate current based on the zero cross point.
[0011]
At the time of starting the induction motor, by performing such phase control, the starting current can be reduced, and the starting torque of the induction motor can be reduced.
[0012]
Also, the phase control is performed when the induction motor is braked. In the phase control at the time of braking, DC braking is performed by performing single-phase half-wave control of the induction motor (for example, rectifying only positive polarity (half cycle) for a single phase). In addition, during a period in which DC braking is not performed (in the above example, a period of negative polarity), a current generated by the power generation operation of the induction motor is fed to a free wheel diode (a freewheel diode, a bypass diode) interposed in parallel with the induction motor. (Also referred to as a diode) to cause a short circuit and reflux to discharge. As described above, since the DC braking and the recirculation / discharge are repeated every half cycle in which the polarity is changed, the braking can be performed more rapidly than when only the DC braking is performed.
[0013]
As described above, since the starting current is reduced by performing phase control at the time of starting and electric braking can be performed at the time of braking, even if the size of the induction motor is increased, the return spring is not increased, and Highly accurate fluid discharge control can be performed.
[0014]
Further, the above effects can be achieved at a low cost with a simple configuration without increasing the number of separate circuits for DC braking.
[0015]
Preferably, the AC power supply is a three-phase AC power supply, the induction motor is a three-phase induction motor, the triac is interposed for each phase, and the free wheel diode is the three-phase induction power supply. The two-phase induction motor is interposed in parallel with the two-phase induction motor, and during the braking, one phase of the two-phase induction motor is controlled while the other phase of the three-phase induction motor is stopped. Is configured.
[0016]
In this case, a general-purpose three-phase AC motor can be used, and a general-purpose three-phase induction motor that has excellent steady-state speed stability without the need for starting torque from others can be used. It is possible to maintain high performance. Also, at the time of braking, current is circulated in a circuit including a two-phase and free-wheel diode of a three-phase induction motor. At this time, since the two phases are connected in series, if only one phase is controlled in phase and the other phase is kept on, there is no need to perform phase control for two phases and synchronize. Therefore, control can be easily performed.
[0017]
Preferably, the photovoltaic device further comprises a photocoupler interposed between the AC power supply and the induction motor and detecting a zero-crossing time of the AC power supply, wherein the triac is controlled based on the zero-crossing time detected by the photocoupler. It is configured to
[0018]
As described above, the triac cannot be turned off without zero crossing. Therefore, it is necessary to detect the time of zero crossing. On the other hand, a photocoupler is an element that includes an LED and a phototransistor, and whose input side and output side are electrically insulated. By interposing such a photocoupler for zero-cross detection of an AC power supply, a circuit can be configured with a simple configuration without greatly changing the specification from the conventional configuration.
[0019]
Preferably, it further comprises a diode interposed between the AC power supply and the induction motor, and a protection triac interposed in parallel with the diode, and turns on the protection triac at startup, The circuit including the free wheel diode is turned on after the protection triac is turned off during braking.
[0020]
As described above, the triac cannot be turned off without zero crossing. Therefore, when the braking signal transmitted to the induction motor and the ON signal transmitted to the circuit including the free wheel diode are simultaneously transmitted, the induction motor may not completely shift to the braking control before the zero crossing. In this case, a short-circuit current may flow in the AC power supply, and an extra load is applied to the AC power supply, which is not preferable.
[0021]
For this reason, by turning on the triac at the time of starting, an AC current flows from the AC power supply, and by turning off the triac at the time of braking, only the current from the AC power supply flows through the diode, and the diode is short-circuited to the AC power supply. By turning on the circuit including the free wheel diode after preventing the current from flowing, it is possible to effectively prevent the short-circuit current from flowing into the AC power supply.
[0022]
Further, the reciprocating pump according to the present invention includes a control circuit for the reciprocating pump, an AC power supply, an operating unit for discharging fluid, and an induction motor for generating a driving force for reciprocating the operating unit. And an elastic body for urging the operating portion in a direction opposite to a moving direction of the induction motor driven by the driving.
[0023]
By performing the braking control using the biasing force of the elastic body while performing the control using the control circuit as described above, it is possible to perform more precise control. Control can be performed with higher precision without increasing the elastic force of
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic circuit diagram showing a control device for a reciprocating pump according to an embodiment of the present invention.
[0025]
The control device 3 of the reciprocating pump according to the present embodiment is applied to a reciprocating pump that reciprocates an operating unit (discussed below) for discharging a fluid by driving an induction motor 2 connected to an AC power supply 1. A control device for a reciprocating pump for controlling a dynamic pump, comprising a triac Q1 to Q3 interposed between the AC power supply 1 and the induction motor 2, and interposed in parallel with the induction motor 2. A freewheel diode D2 for controlling the phase of the triacs Q1 to Q3 when the induction motor 2 is started, and controlling the phase for controlling the triac Q1 to perform a single-phase half-wave control during braking. 2 and the freewheel diode D2.
[0026]
The AC power supply 1 is a three-phase AC power supply (having R, S, and T phases), and the induction motor 2 is a three-phase induction motor (having U, V, and W phases). The triacs Q1 to Q3 are interposed for each phase (between the R and U phases, between the S and V phases, between the T and W phases), and the free wheel diode D2 is connected to the three-phase induction motor 2. And the other phase (W-phase) of the three-phase induction motor 2 is stopped and controlled at the time of braking, and the two-phase (U-phase and U-phase) And the V phase) of the induction motor 2 is configured to control the phase of any one phase (U phase). Further, in the present embodiment, a triac Q5 connected in series with the free wheel diode is provided so that a short-circuit current does not flow through the free wheel diode D2 except during braking.
[0027]
In the reciprocating pump control device 3 according to the present invention, triacs Q1 to Q3 (also referred to as bidirectional thyristors) are interposed between the AC power supply 1 and the induction motor 2 as shown in FIG. . The triacs Q1 to Q3 are semiconductor elements that can be switched by one gate regardless of the polarity of the voltage. Like the thyristor, the triacs Q1 to Q3 are turned on when a current flows through the gate (receiving a trigger signal). However, once turned on, the triacs Q1 to Q3 do not turn off even if the gate current becomes zero. To turn off, the current flowing through the triacs Q1 to Q3 needs to be zero. Since the reciprocating pump according to the present invention uses the AC power supply 1, the reciprocating pump is zero-crossed (current becomes 0) in a half cycle and is turned off. Therefore, the phase is controlled by controlling the start signal based on the gate current based on the zero cross point.
[0028]
FIG. 2 is a time chart showing the operation of the control device of FIG. 2A shows a start signal, FIGS. 2B to 2F show switching control states of the respective triacs Q1 to Q5, and FIG. 2G shows a state of the induction motor 2 by the triacs Q1 to Q5. It shows the change in the rotation speed. The triac Q4 will be described later. FIG. 3 is a diagram showing a voltage waveform of the induction motor during the phase control of FIG. FIG. 3A shows a voltage waveform at the time of startup, and FIG. 3B shows a voltage waveform for the U phase at the time of braking. The triac is not turned off immediately because an induction current is generated by the induction motor 2 even after the zero crossing, but for simplicity in FIG. 3, the induction by the induction motor 2 is ignored. is there. Although the phase angle is constant in FIG. 3 for simplicity, it may be changed so that the induction motor 2 is appropriately and optimally controlled as described later.
[0029]
As shown in FIG. 2A, start control of the induction motor 2 is performed by an external start signal (time t). ₀ ). At this time, a start signal is transmitted to each gate of the triacs Q1 to Q3, and the above-described phase control is performed on the triacs Q1 to Q3 as shown in FIGS. 2 (b) to 2 (d). By performing the phase control as shown in FIG. 3A, the starting current can be reduced, and the starting torque of the induction motor 2 can be reduced. When the induction motor 2 reaches a predetermined rotation speed (time t ₁ 3) The triacs Q1 to Q3 are controlled to be in an on state (a state in which current flows in all phases), and the induction motor 2 operates in a constant manner to drive an operating portion (described later) of the reciprocating pump in the fluid discharge direction.
[0030]
After a predetermined period (time t ₂ ), The braking control of the induction motor 2 is performed. The phase control is also performed when the induction motor 2 is braked. In the phase control at the time of braking, the induction motor 2 is subjected to the single-phase only half-wave rectification control (in this embodiment, the single-phase (U-phase) is rectified only to the positive polarity (half cycle) as shown in FIG. 3B). ) To perform DC braking. In addition, the triac Q5 interposed in series with the free wheel diode D2 (also referred to as a freewheeling diode or a bypass diode) is turned on (time t). ₃ ). As a result, during the period in which the DC braking is not performed (the period of the negative polarity in the above example, that is, the period in which the waveform is a broken line in FIG. 3B), the current generated by the power generation action of the induction motor 2 is reduced. The freewheel diode D2 interposed in parallel with the induction motor 2 causes a short circuit and reflux, and discharges the generated current. That is, the current is circulated by the circuit including the two phases (U phase, V phase) and the free wheel diode D2 of the three-phase induction motor 2 (the remaining one phase (W phase) is stop control).
[0031]
At this time, since the two phases (U-phase and V-phase) are connected in series, only one phase (for the U-phase) is phase-controlled by the triac Q1, and the other phase (V-phase) is turned on by the triac Q2. If the state is maintained, phase control is performed for two phases (U phase and V phase) and there is no need to synchronize with each other, so that control can be easily performed. As described above, since the DC braking and the reflux / discharge are repeated every half cycle in which the polarity is changed, only the DC braking is performed, and the braking can be performed more rapidly than in the case where the discharging period is not provided.
[0032]
As described above, the starting current can be reduced by controlling the phase at the time of starting, and the electric braking can be performed at the time of braking. Therefore, even if the size of the induction motor 2 is increased, the return spring is not increased. In addition, highly accurate fluid discharge control can be performed.
[0033]
Further, the above effects can be achieved at a low cost with a simple configuration without increasing the number of separate circuits for DC braking.
[0034]
Furthermore, since it is possible to use a general-purpose three-phase induction motor 2 that uses a general three-phase alternating current, does not require any other starting torque, and has excellent steady-state speed stability, it can be configured at a lower cost and reliability. It is possible to maintain high performance.
[0035]
In the present embodiment, as described above, the embodiment using the three-phase AC power supply 1 and the three-phase induction motor 2 has been described as an example. However, the present invention is not limited to this. The invention is also applicable to induction motors and other polyphase induction motors.
[0036]
In the present embodiment, as shown in FIG. 1, a diode D1 interposed between the AC power supply 1 and the induction motor 2 and a protection triac Q4 interposed in parallel with the diode D1 are connected. The protection triac Q4 is turned on at the time of startup, and the circuit including the free wheel diode D2 is turned on after the protection triac Q4 is turned off at the time of braking.
[0037]
As described above, the triac cannot be turned off without zero crossing. Therefore, when the braking signal transmitted to the induction motor 2 and the ON signal transmitted to the circuit including the free wheel diode D2 are simultaneously transmitted, the induction motor 2 may not completely shift to the braking control before the zero crossing. is there. In this case, a short-circuit current may flow into the AC power supply 1 via the free wheel diode D2, and an unnecessary load is applied to the AC power supply 1, which is not preferable.
[0038]
Therefore, at the time of startup (time t ₁ ) Turns on the triac Q4, so that an AC current flows from the AC power supply 1 and a braking operation (time t). ₂ ), The triac Q4 is turned off so that only the current from the AC power supply 1 flows through the diode D1, and the diode D1 prevents short-circuit current from flowing into the AC power supply 1 (at time t). ₃ By turning on the circuit including the free wheel diode D2, it is possible to effectively prevent a short-circuit current from flowing into the AC power supply 1.
[0039]
Time t ₂ And t ₃ (Dead time DT), it is possible to configure a more reliable control device.
[0040]
The dead time DT can be variously set in accordance with the characteristics of the triac. Further, the dead time DT can be made unnecessary or shortened by suitably monitoring the alternating current irrespective of hardware means or software means.
[0041]
Here, means for controlling each of the triacs Q1 to Q5 will be described. In the present embodiment, as shown in FIG. 1, further provided are photocouplers PC1 to PC3 interposed between the AC power supply 1 and the induction motor 2 and detecting a zero-cross time of the AC power supply 1, The triacs Q1 to Q5 are configured to perform control based on a zero crossing time detected by the photocouplers PC1 to PC3.
[0042]
In the case of FIG. 1, the photocouplers PC1 to PC3 that detect the zero-crossing time of the AC power supply 1 at the time of startup and at the time of constant operation (during three-phase operation) are used to detect each phase of the three-phase AC power supply 1 independently. The photocouplers PC1 to PC3 are star-connected in correspondence with the star-connected three-phase AC power supply 1. Further, in order to detect a zero-crossing time of the AC power supply 1 (U-phase for controlling the phase) during braking (during single-phase operation), the photocoupler PC4 is connected to the U-phase of the induction motor 2 connected in series. It is interposed in parallel with the V phase. As shown in FIG. 1, the diode D4 is interposed in series with the photocoupler PC4 in a direction in which only the polarity direction current of the phase control in the U phase at the time of braking is passed. The generated current is configured not to flow through the photocoupler PC4.
[0043]
As described above, the triacs Q1 to Q5 cannot be turned off without zero crossing. Therefore, it is necessary to detect the time of zero crossing. On the other hand, each of the photocouplers PC1 to PC3 is an element including an LED and a phototransistor, and whose input side and output side are electrically insulated. By interposing such photocouplers PC1 to PC3 for zero-cross detection of the AC power supply 1, it is possible to configure a circuit with a simple configuration without greatly changing specifications from the conventional configuration.
[0044]
Here, a specific example for controlling using the photocouplers PC1 to PC4 will be described. FIG. 4 is a schematic diagram showing an example of electrical control of the control device of FIG. In the present embodiment, a power supply voltage detector 31 that detects a power supply voltage between the respective phases of the three-phase AC power supply 1, a voltage detected by the power supply voltage detector 31, and signals from the photocouplers PC1 to PC4. And a start signal, and a CPU 32 for outputting a trigger signal to the triacs Q1 to Q5 for suitably controlling.
[0045]
The power supply voltage detector 31 detects a power supply voltage between the phases of the AC power supply 1 and transmits it to the CPU 32. The CPU 32 calculates an optimum phase angle according to the voltage detected by the power supply voltage detector 31 based on the zero cross signal detected by the photocouplers PC1 to PC4, and outputs a trigger signal to each of the triacs Q1 to Q5. Send. As the phase angle changes, the heat generation and the stop accuracy of the induction motor 2 change. In the present embodiment, the CPU 32 adjusts each power supply voltage according to each power supply voltage so that the optimum value obtained by an experiment or the like is obtained. It has table data and checks the table data with the voltage value detected by the power supply voltage detector 31 to adjust the trigger signal.
[0046]
Further, the photocoupler PC4 detects a zero-cross signal after a predetermined fixed period as a starting point of the braking control, and based on this, controls the phase of the triac Q1 to turn off each of the triacs Q3 and Q4, After the time DT, the triac Q5 is zero-cross started.
[0047]
Note that the phase control at the time of starting and braking, the transition timing to the constant operation, the braking timing, and the control of the dead time DT may be set externally or may be set internally in advance.
[0048]
By optimizing the settings of the CPU 32, it is possible to configure the control circuit 3 of the reciprocating pump that is more stable and easy to change the settings.
[0049]
Further, in the present embodiment, the diode D1 and the protection triac Q4 are interposed for short-circuit prevention. However, by optimizing the control in the CPU 32 as described above, these elements are not necessarily required. , A simpler configuration can be achieved.
[0050]
In the present embodiment, as shown in FIG. 4, electrical control (software control) is performed using the CPU 32, but mechanical control is performed using a circuit configuration using elements such as a capacitor and a comparator. (In terms of hardware).
[0051]
Next, a reciprocating pump to which the control device of the present embodiment is applied will be described. FIG. 5 is a schematic diagram of a reciprocating pump to which the control device of FIG. 1 is applied. In FIG. 5, only the pump section 4 is shown as an enlarged sectional view, and other configurations are shown in a block diagram, and details are omitted. Also in FIG. 5, the AC power supply 1 has three phases, but the connection is omitted and conceptually shown.
[0052]
As shown in FIG. 5, the reciprocating pump according to the present embodiment includes a control circuit 3 for the reciprocating pump, an AC power supply 1, a pump head unit 4 including an operating unit 41 for discharging fluid, and A motor including an induction motor 2 for generating a driving force for reciprocating the operating portion 41 and a return spring 42 which is an elastic body for urging the operating portion 41 in a direction opposite to a moving direction of the induction motor 2 when driven. It is.
[0053]
The pump head section 4 includes the above-described operating section 41 and the return spring 42, an inflow transport section 43 having an inflow-side transport path through which fluid flows, and a discharge side having a discharge-side transport path through which the fluid is discharged by the operating section 41. And a transport unit 44. The operating section 41 includes a shaft section 411 that reciprocates by driving the induction motor 2 and a diaphragm 412 that is a contact section with a fluid.
[0054]
The reciprocating pump shown in FIG. 5 further includes a linear motion converting mechanism 5 such as a cam mechanism and a rack and pinion mechanism for converting the rotational motion of the induction motor 2 into a linear motion.
[0055]
When the induction motor 2 is started from the AC power supply 1 via the control device 3 by the start signal, the rotational motion caused by the drive of the induction motor 2 is converted into a linear motion by a linear motion converting mechanism 5 such as a cam mechanism, and the pump head is driven. The shaft section 411 of the section 4 is moved in a direction in which the diaphragm 412 is pressed. Since the diaphragm 412 is pressed by the shaft portion 411, the fluid flowing into the pump head portion 4 is discharged through the discharge-side transport path of the discharge-side transport portion 44. In addition, the return spring 42 is urged in a direction in which the shaft 411 is separated from the diaphragm 412 by the movement of the shaft 411 toward the diaphragm 412.
[0056]
When the braking of the induction motor 2 is controlled by the control device 3, the induction motor 2 is electrically braked, and the shaft 411 moves in a direction away from the diaphragm 412 by the urging force of the return spring 42. As a result, the diaphragm 412 also has a reduced pressing force from the shaft portion 411 and is pushed back toward the shaft portion 411 by the reaction force of the fluid flowing from the inflow-side transport path of the inflow-side transport portion 43. At this time, the fluid from the inflow side transport unit 43 is stored in the pump head unit 4 as a discharge amount when the operating unit 42 operates next time.
[0057]
As described above, by performing the braking control using the biasing force of the elastic return spring 42 while performing the control using the control circuit 3 as described above, more accurate control can be performed, and Even if the size of the induction motor 2 is increased, higher-precision control can be performed without increasing the elastic force of the return spring 42, which is an elastic body.
[0058]
The operating section 41 is applicable not only to the case where the shaft section 411 and the diaphragm 412 are used, but also to any type of reciprocating pump such as a plunger type or a type using a bellows.
[0059]
【The invention's effect】
According to the control circuit of the reciprocating pump according to the present invention, the starting current can be reduced by performing phase control at the time of starting, and electric braking can be performed at the time of braking. Thus, the fluid discharge control can be performed with high accuracy without increasing the size of the return spring.
[0060]
Further, the above effects can be achieved at a low cost with a simple configuration without increasing the number of separate circuits for DC braking.
[0061]
Furthermore, since it is possible to use a general-purpose three-phase induction motor 2 that uses a general three-phase alternating current, does not require any other starting torque, and has excellent steady-state speed stability, it can be configured at a lower cost and reliability. It is possible to maintain high performance.
[Brief description of the drawings]
FIG. 1 is a schematic circuit diagram showing a control device of a reciprocating pump according to an embodiment of the present invention.
FIG. 2 is a time chart illustrating an operation of the control device of FIG. 1;
FIG. 3 is a schematic diagram showing an example of electrical control of the control device of FIG. 1;
FIG. 4 is a schematic diagram showing an example of electrical control of the control device of FIG. 1;
FIG. 5 is a schematic diagram of a reciprocating pump to which the control device of FIG. 1 is applied.
[Explanation of symbols]
1 AC power supply (three-phase AC power supply)
2 Induction motor (three-phase induction motor)
3 control device
41 Working part
42 Return spring
D2 free wheel diode
PC1 to PC4 Photocoupler
Q1 to Q5 Triac

Claims (5)

A control device for a reciprocating pump applied to a reciprocating pump for reciprocating an operating unit for discharging a fluid by driving an induction motor connected to an AC power supply, for controlling the reciprocating pump,
A triac interposed between the AC power supply and the induction motor, and a free wheel diode interposed in parallel with the induction motor,
When starting the induction motor, controlling the phase of the triac, and controlling the phase of the triac to perform a single-phase half-wave control while braking the induction motor, and circulating a current to the induction motor and the freewheel diode. Characteristic reciprocating pump control device. The AC power supply is a three-phase AC power supply, and the induction motor is a three-phase induction motor,
The triac is interposed for each phase, the free wheel diode is interposed in parallel with any two phases of the three-phase induction motor, and the other phase of the three-phase induction motor at the time of braking. The control device for a reciprocating pump according to claim 1, wherein stop control is performed and one of the two-phase induction motors is phase-controlled. It further includes a photocoupler that is interposed between the AC power supply and the induction motor, and detects a zero-crossing time of the AC power supply,
3. The control device for a reciprocating pump according to claim 1, wherein the triac is controlled based on a zero-crossing time detected by the photocoupler. A diode interposed between the AC power supply and the induction motor, and a protection triac interposed in parallel with the diode,
The reciprocating motion according to any one of claims 1 to 3, wherein the protection triac is turned on at the time of starting, and the circuit including the free wheel diode is turned on after turning off the protection triac at the time of braking. Pump control device. A control circuit for the reciprocating pump according to any one of claims 1 to 4,
AC power supply,
An operating part for discharging a fluid,
An induction motor for generating a driving force for reciprocating the operating portion,
An elastic body for urging the operating portion in a direction opposite to a moving direction of the induction motor driven by the induction motor.

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