Electromagnet control circuit

Abstract

The utility model relates to the technical field of electromagnet driving, in particular to an electromagnet control circuit, which comprises a boost power supply circuit, a switch control circuit and an electromagnet circuit, and is characterized in that the electromagnet circuit is respectively connected with the boost power supply circuit and the switch control circuit; through a two-stage voltage control mode, the driving current for keeping the phase is effectively reduced, the temperature rise of an electromagnet coil is reduced, meanwhile, a slow start mechanism is formed, and surge current impact caused by level switching is relieved.

Description

Technical Field

[0001] The utility model relates to the technical field of electromagnet drive, in particular to an electromagnet control circuit. Background Art

[0002] The current magnetic effect is a commonly used technology in daily life. By passing an electric current through a coil, a magnetic effect is formed, and the magnetism of the coil is controlled by the magnitude of the current. It is commonly used in scenarios where magnetic force changes. The cash box is one of the usage scenarios. Through the electromagnet control circuit, the switch of the electromagnet is controlled to realize the closing of the cash box.

[0003] In the prior art, the electromagnet control circuit is driven by a single power supply. Under long-term driving conditions, the electromagnet is prone to heat generation, resulting in aging and failure. At the same time, there is a surge current when driving the electromagnet, which is likely to cause electrical impact on components, leading to damage or even failure of the components. Summary of the Utility Model

[0004] Based on the above-mentioned disadvantages of the prior art, the utility model provides an electromagnet control circuit to solve the problems of serious heat generation of the electromagnet under long-term startup and the impact of surge current on components.

[0005] To achieve the above object, the utility model provides an electromagnet control circuit, including a boost power supply circuit, a switch control circuit, and an electromagnet circuit. The electromagnet circuit is respectively connected to the boost power supply circuit and the switch control circuit; the boost power supply circuit includes a boost conversion chip, a first inductor, a second inductor, a first resistor, a second resistor, a third resistor, a first capacitor, and a first diode. The boost conversion chip is a DC-DC conversion chip, including a VIN pin, an EN pin, an NC pin, an SW pin, an FB pin, and a GND pin. On the first aspect, the VIN pin is connected to the power supply through the first inductor, and the first capacitor is grounded between the first inductor and the VIN pin; on the first aspect, the EN pin is connected to the start / stop control terminal, and on the second aspect, it is grounded through the first resistor; the SW pin is connected to the anode of the first diode, and the cathode of the first diode is connected to the FB pin through the second resistor on the first aspect and forms an external connection terminal on the third aspect; the FB pin is grounded through the third resistor; the second inductor is connected in parallel between the VIN pin and the SW pin.

[0006] Optionally, the boost power supply circuit further includes a second capacitor, and the cathode of the first diode is grounded through the second capacitor.

[0007] Further, the switch control circuit includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, a first triode, and a second triode. The base of the first triode is connected to the power-on / power-off control terminal through the fourth resistor, and the fourth resistor and the power-on / power-off control terminal are grounded through the fifth resistor. The base of the second triode is connected to the base of the first triode through the sixth resistor in one aspect, grounded through the third capacitor in another aspect, grounded through the seventh resistor in a third aspect, and connected to the emitter of the first triode in a fourth aspect. The emitter of the second triode is grounded. The collector of the second triode is connected to the collector of the first triode and forms an external connection terminal. The first triode and the second triode together form a Darlington tube structure.

[0008] Optionally, the switch control circuit further includes a fourth capacitor, and the fourth resistor and the base of the first triode are grounded through the fourth capacitor.

[0009] Further, the electromagnet circuit includes a DC electromagnet and a second diode. The second diode is connected in parallel with the DC electromagnet. The cathode of the second diode is connected to the external connection terminal of the boost power supply circuit, and the anode of the second diode is connected to the external connection terminal of the switch control circuit.

[0010] By the above method, using a two-stage voltage control method, the drive current of the holding phase is effectively reduced, the temperature rise of the electromagnet coil is reduced, and the second capacitor and the fourth capacitor form a soft start mechanism to relieve the surge current impact caused by level switching. Description of the Drawings

[0011] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0012] Figure 1 It is a schematic circuit diagram of the electromagnet control circuit. Detailed Embodiments

[0013] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0014] It should be noted that the illustrations provided in this embodiment only schematically illustrate the basic concept of the present utility model. Therefore, only the components related to the present utility model are shown in the drawings, rather than being drawn according to the number, shape, and size of the components in actual implementation. The form, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the layout form of its components may also be more complex.

[0015] Referring to Figure 1 , an electromagnetic control circuit is provided in an embodiment of the present utility model, including a boost power supply circuit 1, a switch control circuit 2, and an electromagnetic circuit 3. The electromagnetic circuit is respectively connected to the boost power supply circuit 1 and the switch control circuit 2. The boost power supply circuit 1 increases the voltage of the electromagnetic circuit 3 to enable the electromagnetic circuit 3 to work; the switch control circuit 2 releases the power of the electromagnetic circuit 3 to stop the electromagnetic circuit 3 from working.

[0016] The boost power supply circuit 1 includes a boost conversion chip U1, a first inductor L1, a second inductor L2, a first resistor R1, a second resistor R2, a third resistor R3, a first capacitor C1, and a first diode D1. The boost conversion chip U1 is a DC-DC conversion chip, including a VIN (power input) pin, an EN (enable) pin, an NC (unused) pin, an SW (switch control) pin, an FB (output voltage feedback) pin, and a GND (ground) pin. The VIN pin is connected to the power supply through the first inductor L1. In this embodiment, the power supply is a 6VDC power supply, and the first capacitor C1 is grounded between the first inductor L1 and the VIN pin; the EN pin is connected to the start / stop control terminal on one hand and grounded through the first resistor R1 on the other hand. The start / stop control terminal activates the conversion chip by sending a high level to the EN pin; the SW pin is connected to the anode of the first diode D1. The cathode of the first diode D1 is connected to the FB pin through the second resistor R2 on one hand and forms an external connection terminal on the third hand; the FB pin is grounded through the third resistor R3; the second inductor L2 is connected in parallel between the VIN pin and the SW pin.

[0017] As a preferred embodiment, the boost power supply circuit 1 further includes a second capacitor C2, and the cathode of the first diode D1 is grounded through the second capacitor C2 to achieve a soft start effect.

[0018] In the above manner, the operation of the boost conversion chip U1 is controlled by the start / stop control terminal. When the start / stop control terminal is at a high level, the boost conversion chip U1 operates to boost the 6VDC power supply to 12V, and the overcurrent protection point is 2A. When the start / stop control terminal is at a low level, the boost conversion chip U1 stops operating, and the boost power supply circuit 1 outputs 5.3VDC. At the same time, the second capacitor C2 is connected to the cathode of the first diode D1 and the ground wire respectively, and can absorb part of the current when the voltage changes, preventing the surge current impact caused by the switching of the start / stop control terminal, achieving the function of soft start.

[0019] The switch control circuit 2 includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a third capacitor C3, a first triode Q1, and a second triode Q2. The base of the first triode Q1 is connected to the power-on / power-off control terminal through the fourth resistor R4. The fourth resistor R4 is grounded through the fifth resistor R5 between the fourth resistor R4 and the power-on / power-off control terminal. The base of the second triode Q2 is connected to the base of the first triode Q1 through the sixth resistor R6 in one aspect, grounded through the third capacitor C3 in the second aspect, grounded through the seventh resistor R7 in the third aspect, and connected to the emitter of the first triode Q1 in the fourth aspect. The emitter of the second triode Q2 is grounded. The collector of the second triode Q2 is connected to the collector of the first triode Q1 and forms an external connection terminal. The first triode Q1 and the second triode Q2 jointly form a Darlington tube structure.

[0020] As a preferred embodiment, the switch control circuit 2 further includes a fourth capacitor C4, and the fourth resistor R4 is grounded through the fourth capacitor C4 between the fourth resistor R4 and the base of the first triode Q1 to achieve the soft start effect.

[0021] The electromagnet circuit 3 includes a DC electromagnet and a second diode D2. The second diode D2 is connected in parallel with the DC electromagnet. The cathode of the second diode D2 is connected to the external connection terminal of the boost power supply circuit 1, and the anode of the second diode D2 is connected to the external connection terminal of the switch control circuit 2.

[0022] Taking the 12VDC electromagnet control circuit as an example, in terms of the switch control circuit 2, in the initial state, the power-on / power-off control terminal is at a low level. The fourth capacitor C4 discharges to 0V through the fourth resistor R4, the sixth resistor R6, the seventh resistor R7, and the base of the first triode Q1 and the base of the second triode Q2. The third resistor C3 discharges to 0V through the fourth resistor R4, the sixth resistor R6, the seventh resistor R7, and the base of the second triode Q2. When it is necessary to power on the electromagnet circuit 3, the power-on / power-off control terminal switches to a high level. At this time, the high-level signal charges the fourth capacitor C4 through the fourth resistor R4. When the fourth capacitor C4 is charged to about 1.2V, the first triode Q1 and the second triode Q2 start to conduct. When the fourth capacitor C4 is charged to about 1.6V, the first triode Q1 and the second triode Q2 start to saturate and conduct completely. When the power-on / power-off control terminal changes from a low level to a high level, a steep level change will be formed. The function of the fourth resistor R4 and the fourth capacitor C4 is to transform this steep level change into a ramp-like level change, so that the first triode Q1 and the second triode Q2 have a gradual process from starting to conduct to saturated conduction, that is, the output impedance of the first triode Q1 and the second triode Q2 has a gradual process. This gradual process causes the current of the electromagnet to also have a gradual process, eliminating the surge current impact when the electromagnet is powered on instantaneously.

[0023] In terms of the boost power supply circuit, when the start / stop control terminal is set to a low level, the boost power supply circuit is in a stopped working state, and the output voltage is 5.3VDC. Since the current calculation formula for the electromagnet in the electromagnet circuit in the holding state is IM = VM / RM, where IM is the current on the cash box electromagnet, RM is the coil resistance of the electromagnet, and VM is the voltage on the electromagnet. At this time, VM = 5.3VDC, rather than the rated driving voltage of the electromagnet, which is 12VDC. Therefore, according to the previous calculation formula, the current on the electromagnet at this time is about 0.44 times the rated driving current, greatly reducing the current value in the holding state of the electromagnet, thereby greatly reducing the temperature rise of the electromagnet and increasing the life and reliability of the electromagnet.

[0024] The above embodiments only illustratively explain the principles and effects of the present invention, rather than limiting the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. An electromagnet control circuit, characterized in that: The invention comprises a boost power supply circuit, a switch control circuit and an electromagnet circuit, wherein the electromagnet circuit is connected to the boost power supply circuit and the switch control circuit respectively; the boost power supply circuit comprises a boost conversion chip, a first inductor, a second inductor, a first resistor, a second resistor, a third resistor, a first capacitor and a first diode; the boost conversion chip is a DC-DC conversion chip, comprising a VIN pin, an EN pin, an NC pin, a SW pin, an FB pin and a GND pin; the VIN pin is connected to a power supply through the first inductor on the first aspect, and the first inductor and the VIN pin are grounded through the first capacitor; the EN pin is connected to a start / stop control terminal on the first aspect, and is grounded through the first resistor on the second aspect; the SW pin is connected to an anode of the first diode, and a cathode of the first diode is connected to the FB pin through the second resistor on the first aspect, and forms an external connection terminal on the third aspect; the FB pin is grounded through the third resistor; the second inductor is connected in parallel between the VIN pin and the SW pin.

2. An electromagnet control circuit as claimed in claim 1, characterized in that: The boost power supply circuit further includes a second capacitor, and the cathode of the first diode is grounded through the second capacitor.

3. An electromagnet control circuit as claimed in claim 1, characterized in that: The switch control circuit includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, a first transistor, and a second transistor. The base of the first transistor is connected to the power-on / power-off control terminal through the fourth resistor, and the fourth resistor and the power-on / power-off control terminal are grounded through the fifth resistor. The base of the second transistor is firstly connected to the base of the first transistor through the sixth resistor, secondly connected to the ground through the third capacitor, thirdly connected to the ground through the seventh resistor, fourthly connected to the emitter of the first transistor, the emitter of the second transistor is grounded, the collector of the second transistor is connected to the collector of the first transistor, and forms an external connection terminal. The first transistor and the second transistor together form a Darlington transistor structure.

4. An electromagnet control circuit as claimed in claim 3, characterized in that: The switch control circuit further includes a fourth capacitor, and the fourth resistor and the base of the first transistor are grounded via the fourth capacitor.

5. An electromagnet control circuit as claimed in claim 1, characterized in that: The electromagnet circuit includes a DC electromagnet and a second diode, the second diode is connected in parallel with the DC electromagnet, the cathode of the second diode is connected to the external connection end of the boost power supply circuit, and the anode of the second diode is connected to the external connection end of the switch control circuit.

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