Control device and control method for electromagnetic plunger pump

Abstract

The invention relates to the field of electromagnetic plunger pumps, and discloses a control device and method for an electromagnetic plunger pump, and the control device comprises a rectification filter circuit and a control circuit. The rectification filter circuit comprises a rectifier D3 and a filter capacitor; the control circuit comprises a plunger pump coil, a diode D1, a diode D2, a switch tube TR1 and a switch tube TR2. According to the invention, the energy of the coil can be recovered to the filter capacitor for use while the plunger pump is controlled to be quickly reset and turned off; compared with the prior art, the loss of the plunger pump coil is greatly reduced, the temperature rise of the plunger pump coil is low, and therefore the use efficiency of the plunger pump can be improved.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic plunger pumps, and particularly to a control device and a control method for an electromagnetic plunger pump. Background Art

[0002] The brief working principle of an electromagnetic plunger pump is as follows: after the electromagnetic plunger pump coil is powered on, the current in the coil gradually rises and starts to generate a magnetic field. The plunger is acted on by the electromagnetic force to overcome the reaction force of the return spring and compress the return spring to move. The air chamber pressure in the pump body decreases, and water enters. When power is cut off and the circuit is turned off, the current in the plunger pump coil decreases. The electromagnetic force acting on the plunger decreases. Under the action of the reaction force of the return spring, the plunger compresses the gas in the direction of spring return, and the air chamber pressure in the pump body becomes larger, and water is discharged. In this way, reciprocating motion during power-on can complete liquid pumping. It can be known from this that when power is cut off and the circuit is turned off, the faster the current in the plunger pump coil drops, the faster the plunger resets, and the smaller the loss of the plunger pump coil.

[0003] Figure 1 Fig. is the coil control circuit diagram in an existing electromagnetic plunger pump. The coil control circuit includes a bidirectional thyristor, a diode D1, and a coil L1 connected in series. The following problems exist in this coil control circuit:

[0004] Reference Figure 2 , Figure 2 is Figure 1 the current waveform of the coil L1 in. When the electromagnetic plunger pump is about to reset, the current in the coil L1 is still at a position relatively close to the peak, and then it slowly drops in the arc trend from the peak to zero of a conventional sine wave ( Figure 2 the current waveform in the ab section in). The reset of the electromagnetic plunger pump mainly depends on the reaction force of the return spring. However, at this time, because the current in the coil L1 is still at a large value and drops slowly, during the period when the current drops to zero, an electromagnetic force opposite to the return spring force is still generated. Therefore, the reset force of the electromagnetic plunger pump is too small, resulting in slow reset of the electromagnetic plunger pump. It can be clearly seen that during the reset of the electromagnetic plunger pump, the current in the ab section of the coil L1 is harmful and not beneficial, greatly increasing the loss of the electromagnetic plunger pump coil, causing the coil temperature to rise too high, being unfavorable for the continuous operation of the plunger pump, and greatly reducing the working efficiency of the electromagnetic plunger pump. Summary of the Invention

[0005] Based on the above problems, the technical problem to be solved by the present invention is to provide a control device and a control method for an electromagnetic plunger pump, which can accelerate the rapid drop of the coil current of the plunger pump to zero, enable the electromagnetic plunger pump to quickly reset, reduce the loss of the plunger pump coil, thereby reducing the temperature rise of the plunger pump coil, and further enabling the electromagnetic plunger pump to continuously work for a long time and improving the working efficiency of the electromagnetic plunger pump.

[0006] To solve the above technical problems, the present application provides a control device for an electromagnetic plunger pump, which includes: a rectifier filter circuit and a control circuit;

[0007] The rectifier filter circuit includes a rectifier and a filter capacitor; the positive input terminal of the rectifier is used to connect to the L line of the AC input power supply, the negative input terminal of the rectifier is used to connect to the N line of the AC input power supply, the positive output terminal of the rectifier is connected to the positive electrode of the filter capacitor, and the negative output terminal of the rectifier is connected to the negative electrode of the filter capacitor and serves as the ground of the control device;

[0008] The control circuit includes a plunger pump coil, a first diode, a second diode, a first switching tube, and a second switching tube; the cathode of the first diode and the drain of the first switching tube are respectively connected to the positive electrode of the filter capacitor, the source of the first switching tube is connected to one end of the plunger pump coil, the other end of the plunger pump coil is respectively connected to the anode of the first diode and the drain of the second switching tube, the cathode of the second diode is connected to the source of the first switching tube, and the anode of the second diode is connected to the negative electrode of the filter capacitor, the source of the second switching tube, and is connected to the ground of the control device.

[0009] Further, the control circuit is also provided with a first resistor, and the source of the second switching tube is connected to the ground of the control device through the first resistor, and the first resistor is used for current sampling detection.

[0010] Further, when the control circuit performs turn-off control, the first switching tube and the second switching tube are turned off simultaneously, and the first diode, the filter capacitor, the second diode, and the plunger pump coil form a freewheeling circuit to transfer the energy stored in the plunger pump coil to the filter capacitor.

[0011] The present application also provides a control method for the above control device of the electromagnetic plunger pump, including the following steps:

[0012] Turn on the AC input voltage, and convert the AC input voltage into a DC voltage through the rectifier filter circuit and supply it to the plunger pump coil to excite the plunger pump coil;

[0013] Turn off the AC input voltage or turn off the drive signals of the first switching tube and the second switching tube, and demagnetize the plunger pump coil through a circuit including the plunger pump coil and a capacitor.

[0014] Further, the circuit also includes a first diode and a second diode. When the plunger pump coil is demagnetized, the demagnetizing current sequentially passes through the first diode, the filter capacitor, the second diode, and the plunger pump coil.

[0015] When the control circuit performs turn-off control, by selecting a suitable capacitance value for the filter capacitor, it is used to adjust the voltage across the filter capacitor after energy recovery. According to the relationship of the demagnetization current slope di / dt = U / L of the plunger pump coil, where U represents the voltage across the plunger pump coil and L represents the inductance of the plunger pump coil. During demagnetization, the greater the voltage across the plunger pump coil, the greater the demagnetization current slope and the faster the current drops; and the voltage across the plunger pump coil in the demagnetization circuit is basically equal to the voltage across the filter capacitor. Therefore, the greater the voltage across the filter capacitor, the faster the current in the plunger pump coil drops, that is, the faster the plunger pump shuts off and resets under the action of the return spring, the smaller the loss of the plunger pump coil, and the lower the temperature rise; the smaller the voltage across the filter capacitor, the slower the current in the plunger pump coil drops, that is, the slower the plunger pump shuts off and resets under the action of the return spring, the greater the loss of the plunger pump coil, and the higher the temperature rise.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] (1) During the demagnetization process, the demagnetization current slope of the plunger pump coil is proportional to the voltage across the filter capacitor. By selecting a suitable capacitance value for the filter capacitor, rapid reset of the electromagnetic plunger pump can be achieved, reducing the loss of the plunger pump coil, with a low temperature rise of the plunger pump coil, thereby improving the usage efficiency of the plunger pump.

[0018] (2) Preferably, the sampling first resistor is used for current sampling detection, which can perform abnormal current limitation and protection, improving the abnormal protection ability of the electromagnetic plunger pump.

[0019] (3) In the prior art, the plunger pump coil starts excitation from zero voltage, with a low initial excitation voltage and slow excitation; while in the present invention's technology, when the plunger pump coil shuts off, the energy is recovered to the filter capacitor. When the plunger pump coil is excited, due to the reason of energy recovery, the initial excitation voltage is high and the excitation is fast; therefore, the recovered energy can be used for the next rapid start of the electromagnetic plunger pump.

[0020] (4) The control device of the present application can also be used as the control device of an electromagnetic vibration table. Description of the Drawings

[0021] Figure 1 is the schematic diagram of the prior art solution;

[0022] Figure 2 is the waveform diagram of the working current of the plunger pump coil in the prior art solution;

[0023] Figure 3 is the schematic diagram of the application of the control circuit in the first embodiment of the present invention;

[0024] Figure 4 is the waveform diagram of the working current of the plunger pump coil in the first embodiment of the present invention;

[0025] Figure 5This is the schematic diagram of the circuit application for the second embodiment of the present invention. Detailed implementation manners

[0026] The circuit of the present invention will be described below in conjunction with the accompanying drawings and embodiments. It should be noted that the specific embodiments described here are only used to explain the present invention and are not used to limit the circuit of the present invention.

[0027] The first embodiment

[0028] As Figure 3 shown, this is the schematic diagram of the application of the control device of the present application. The control device is applied to an electromagnetic plunger pump, and the AC input L / N lines are connected to the circuit through the two AC input ends (i.e., the positive input end and the negative input end) of the rectifier D3.

[0029] The control circuit of this embodiment sequentially includes a rectifier filter circuit 101 and a control circuit 102.

[0030] The rectifier filter circuit 101 includes a rectifier D3 and a filter capacitor C1; the positive input end of the rectifier is used to connect to the L line of the AC input power supply, the negative input end of the rectifier is used to connect to the N line of the AC input power supply, the positive output end of the rectifier is connected to the positive electrode of the filter capacitor, and the negative output end of the rectifier is connected to the negative electrode of the filter capacitor and serves as the ground of the control device.

[0031] The control circuit 102 includes a plunger pump coil L1, a diode D1 (the first diode), a diode D2 (the second diode), a switching transistor TR1 (the first switching transistor), and a switching transistor TR2 (the second switching transistor); the positive electrode of the capacitor C1 is also connected to the intersection point of the cathode of the diode D1 and the drain of the switching transistor TR1. The source of the switching transistor TR1 is connected to one end of the plunger pump coil L1, and the other end of the coil L1 is connected to the intersection point of the anode of the diode D1 and the drain of the switching transistor TR2. The cathode of the diode D2 is connected to the source of the switching transistor TR1, and the anode of the diode D2 is connected to the negative electrode of the capacitor C1, the source of the switching transistor TR2, and is connected to the ground of the control device.

[0032] The working principle of the control device in the first embodiment of the present application is as follows:

[0033] The alternating current input voltage is rectified and filtered by the rectifying and filtering circuit 101 to obtain a stable direct current voltage. When the electromagnetic plunger pump needs to be turned off and reset, the switching transistor TR1 and the switching transistor TR2 are turned off simultaneously. The plunger pump coil L1 conducts freewheeling and demagnetization through a loop that sequentially passes through the diode D1, the filtering capacitor C1, the diode D2, and then returns to the point A of the plunger pump coil L1 from the point B. During the demagnetization process of the plunger pump coil L1, the slope of the demagnetization current of the plunger pump coil L1, di / dt = U / L, where U represents the voltage across the plunger pump coil and L represents the inductance of the plunger pump coil. In the demagnetization loop, the voltage across the plunger pump coil L is basically equal to the voltage across the filtering capacitor C1. That is, the rate of decrease of the demagnetization current is determined by the magnitude of the voltage across the filtering capacitor C1. When the voltage across the filtering capacitor C1 is larger, the current of the plunger pump coil L1 decreases faster, the loss of the plunger pump coil L1 is smaller, and at the same time, the electromagnetic plunger pump resets faster. Theoretically, the fastest reset can be performed according to the descending section ab in the working current waveform of the plunger pump coil as shown in Figure 4 shown.

[0034] According to an embodiment of the present application, a control method for an electromagnetic plunger pump is also provided. It should be noted that the control method for the electromagnetic plunger pump provided in the embodiment of the present application can be used for a control device provided in the embodiment of the present application. The following introduces the control method provided in the embodiment of the present application.

[0035] The control method for the electromagnetic plunger pump provided in the embodiment of the present application includes the following steps:

[0036] Turn on the alternating current input voltage, and convert the alternating current input voltage into a direct current voltage through the rectifying and filtering circuit 101 to supply it to the plunger pump coil L1 so that the plunger pump coil L1 is excited;

[0037] Turn off the alternating current input voltage or the driving signals of the first switching transistor and the second switching transistor, and demagnetize the plunger pump coil L1 through a loop including the plunger pump coil L1, the filtering capacitor C1, the diode D1, and the diode D2. When the plunger pump coil L1 is demagnetized, the switching transistor TR1 and the switching transistor TR2 are turned off simultaneously, and the demagnetization current sequentially passes through the diode D1, the filtering capacitor C1, the diode D2, and the plunger pump coil L1.

[0038] Second Embodiment

[0039] As Figure 5 shown, it is a schematic diagram of the application principle of the control device according to the second embodiment of the present invention. Compared with the first embodiment, the difference is that the control device in the second embodiment of the present invention further includes a resistor R1.

[0040] The positive electrode of the filtering capacitor C1 is connected to the intersection point of the cathode of the diode D1 and the drain of the switching transistor TR1. The source of the switching transistor TR1 is connected to one end of the plunger pump coil L1. The other end of the plunger pump coil L1 is connected to the intersection point of the anode of the diode D1 and the drain of the switching transistor TR2. The cathode of the diode D2 is connected to the source of the switching transistor TR1. The anode of the diode D2 is connected to the negative electrode of the filtering capacitor C1 and one end of the resistor R1 and is grounded to the control device. The other end of the resistor R1 is connected to the source of the switching transistor TR2.

[0041] The resistor R1 is used for current sampling detection. When the electromagnetic plunger pump runs idly or is blocked during actual application, it can limit the peak current of the plunger pump coil L1, playing a protective role and also reducing the loss and temperature rise when the electromagnetic plunger pump operates abnormally.

[0042] The turn-off control principle of the control device in this embodiment is the same as that in the first embodiment and will not be elaborated here.

[0043] The present invention is also applicable to an electromagnetic vibration table. Its connection method and working principle are roughly the same as those applicable to the electromagnetic plunger pump and will not be elaborated here. The above are only some embodiments of the present invention. Those skilled in the art to which the present invention pertains can also make changes and modifications to the above specific embodiments. Therefore, the present invention is not limited to the above embodiments, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A control device for an electromagnetic plunger pump, characterized in that: Comprising: A rectifying and filtering circuit and a control circuit; The rectifying and filtering circuit includes a rectifier and a filter capacitor; the positive input terminal of the rectifier is used to connect to the L line of the AC input power supply, the negative input terminal of the rectifier is used to connect to the N line of the AC input power supply, the positive output terminal of the rectifier is connected to the positive electrode of the filter capacitor, and the negative output terminal of the rectifier is connected to the negative electrode of the filter capacitor and serves as the ground of the control device; The control circuit includes a plunger pump coil, a first diode, a second diode, a first switching tube, and a second switching tube; the cathode of the first diode and the drain of the first switching tube are respectively connected to the positive electrode of the filter capacitor, the source of the first switching tube is connected to one end of the plunger pump coil, the other end of the plunger pump coil is respectively connected to the anode of the first diode and the drain of the second switching tube, the cathode of the second diode is connected to the source of the first switching tube, and the anode of the second diode is connected to the negative electrode of the filter capacitor, the source of the second switching tube and is connected to the ground of the control device.

2. The control device for an electromagnetic plunger pump according to claim 1, characterized in that: The control circuit is further provided with a first resistor, and the source of the second switching tube is connected to the ground of the control device through the first resistor, and the first resistor is used for current sampling detection.

3. The control device for an electromagnetic plunger pump according to claim 1, characterized in that: When the control circuit performs turn-off control, the first switching tube and the second switching tube are turned off simultaneously, and the first diode, the filter capacitor, the second diode, and the plunger pump coil form a freewheeling circuit to transfer the energy stored in the plunger pump coil to the filter capacitor.

4. A control method for the control device of the electromagnetic plunger pump according to claim 1, comprising the following steps: Turn on the AC input voltage, and convert the AC input voltage into a DC voltage through the rectifying and filtering circuit to supply it to the plunger pump coil to excite the plunger pump coil; Turn off the AC input voltage or turn off the drive signals of the first switching tube and the second switching tube, and demagnetize the plunger pump coil through a circuit including the plunger pump coil and a capacitor.

5. The control method for an electromagnetic plunger pump according to claim 1, characterized in that: The circuit further includes a first diode and a second diode. When the plunger pump coil is demagnetized, the demagnetizing current sequentially passes through the first diode, the filter capacitor, the second diode, and the plunger pump coil.

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