Relay drive circuit capable of pressure reduction retention

Abstract

The utility model discloses a relay drive circuit that can reduce pressure and keep, it includes buck conversion unit and switching unit, the buck conversion unit has the output terminal of configuration to the drive unit power supply of relay, the switching unit has the drive signal access terminal of configuration to access relay drive signal, the switching unit includes charging resistance, electric capacity and switch tube, one end of charging resistance is connected in drive signal access terminal, and the other end is connected in the gate of switch tube, one end of electric capacity is connected in the gate of switch tube and the connecting point of charging capacitor, and the other end is grounded, the anode of switch tube is connected buck conversion unit, and the cathode is grounded. The utility model under the premise of realizing relay circuit initial high voltage lap joint low voltage keeps, and circuit is simple and reliable, does not depend on additional control signal, and the cost is low.

Description

Technical Field

[0001] This utility model belongs to the field of inverters, specifically relating to a relay drive circuit capable of voltage reduction and retention. Background Technology

[0002] Currently, traditional relay drive circuit designs use a single transistor or MOSFET for direct drive. This results in a constant drive voltage throughout operation, leading to significant relay losses and high coil temperatures, further increasing overall system losses. Some solutions address this issue by connecting a low-voltage source after the high-voltage relay contacts are connected, thus maintaining contact closure with low voltage. However, these solutions often require multiple control signals or power supplies, complicating the circuit structure, compromising reliability, and increasing costs.

[0003] The information disclosed in the background section is only intended to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content

[0004] In view of this, the present invention provides a relay drive circuit capable of voltage reduction and holding. Under the premise of realizing the initial high voltage connection and low voltage holding of the relay circuit, the circuit is simple and reliable, does not rely on additional control signals, and has low cost.

[0005] The present invention adopts the following technical solution: A relay drive circuit capable of buck-voltage holding includes a buck converter unit and a switching unit. The buck converter unit has an output terminal configured to supply power to a relay drive unit, and the switching unit has a drive signal input terminal configured to receive a relay drive signal. The switching unit includes a charging resistor, a capacitor, and a switching transistor; one end of the charging resistor is connected to the drive signal input terminal, and the other end is connected to the gate of the switching transistor; one end of the capacitor is connected to the connection point between the gate of the switching transistor and the charging resistor, and the other end is grounded; the anode of the switching transistor is connected to the buck converter unit, and the cathode is grounded.

[0006] In a preferred embodiment, the buck converter unit includes a plurality of voltage divider resistors, and the anode of the switching transistor is connected in series with one of the voltage divider resistors.

[0007] In a more preferred embodiment, the plurality of voltage divider resistors include a first resistor, a second resistor, and a third resistor, wherein the first resistor and the second resistor are connected in series with each other; one end of the third resistor is connected to the connection point of the first resistor and the second resistor, and the other end of the third resistor is connected in series with the anode of the switching transistor and then in parallel with both sides of the second resistor.

[0008] In a further preferred embodiment, the output terminal of the buck converter of the buck converter unit is connected to the connection point of the first resistor and the second resistor; the buck converter unit also has a feedback voltage signal terminal configured to receive a feedback voltage signal, the feedback voltage signal terminal being connected to the connection point of the first resistor and the second resistor.

[0009] In a specific and preferred embodiment, the switching transistor includes a depletion-type N-MOS transistor, the drain of the N-MOS transistor is connected to the third resistor, and the source is grounded.

[0010] In a preferred embodiment, the switching transistor is configured to be in a conducting state when a low-level signal is received at the drive signal input terminal, and in a disconnected state when a high-level signal is received at the drive signal input terminal and the voltage of the capacitor is charged to the threshold voltage of the switching transistor.

[0011] In a more preferred embodiment, the switching transistor includes a MOSFET with its source grounded.

[0012] In a preferred embodiment, the switching unit further includes a pull-down resistor, one end of which is connected to the junction point between the gate of the switching transistor and the capacitor, and the other end is grounded.

[0013] In a preferred embodiment, a signal isolation diode is connected between the switching unit and the drive signal access terminal.

[0014] In a preferred embodiment, the drive signal input terminal is also connected to the relay drive unit. More preferably, the positive terminal of the signal isolation diode is connected to the drive signal input terminal, and the negative terminal is connected to the charging resistor of the switching unit.

[0015] The present invention adopts the above solution and has the following advantages: This invention discloses a relay drive circuit that utilizes the delay of RC charging to control the output voltage adjustment of a buck converter. It is simple, reliable, and low-cost; only a single drive signal is needed to achieve the power switching between high-voltage connection and low-voltage holding of the relay. While achieving initial high-voltage connection and low-voltage holding of the relay circuit, the circuit is simple, reliable, does not rely on additional control signals, and is low-cost. Attached Figure Description

[0016] To more clearly illustrate the technical solution of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a block diagram of a relay driving circuit according to an embodiment of the present utility model.

[0018] Figure 2 This is a circuit diagram of a relay driving circuit according to an embodiment of the present invention.

[0019] Figure 3 This is a voltage change graph from a simulation example.

[0020] in: 1 – Buck converter unit; 11 – Buck converter; 2 – Switching unit; 3 – Relay drive unit. Detailed Implementation

[0021] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art. It should be noted that the description of these embodiments is intended to aid in understanding the present invention, but does not constitute a limitation thereof.

[0022] The embodiment relates to a relay drive circuit capable of voltage reduction and holding, used to switch the relay contacts closed and open. (See reference...) Figure 1 As shown, the relay drive circuit includes a buck converter unit 1 and a switching unit 2. The switching unit 2 is connected to the buck converter unit 1, and the buck converter unit 1 is connected to the relay drive unit 3 to supply power to the relay drive unit 3. Combined with... Figure 2 As shown, the buck converter 1 has an output terminal Vrelay configured to supply power to the relay drive unit 3. This output terminal Vrelay is connected to the relay drive unit 3, thereby applying voltage to both sides of the drive components such as the relay coil. The switching unit 2 has a drive signal input terminal Dr_rly configured to receive relay drive signals. This drive signal input terminal Dr_rly is also connected to the relay drive unit 3. The drive signal input to the drive signal input terminal Dr_rly can act on the switching unit 2 to adjust the magnitude of the voltage output by the buck converter 1, and can also act on the control circuit of the relay drive unit 3.

[0023] Buck converter unit 1 includes a buck converter 11 and multiple voltage divider resistors. The buck converter 11 has a step-down circuit, and the multiple voltage divider resistors constitute the feedback network of the buck converter 11. Specifically, the multiple voltage divider resistors include a first resistor R1, a second resistor R2, and a third resistor R3, wherein the first resistor R1 and the second resistor R2 are connected in series; one end of the third resistor R3 is connected to the connection point of the first resistor R1 and the second resistor R2, and the other end is grounded through the switching unit 2. The output terminal of the buck converter 11 of buck converter unit 1 is connected to the connection point of the first resistor R1 and the second resistor R2; a feedback voltage signal terminal Vfb is also connected to the connection point of the first resistor R1 and the second resistor R2. The feedback voltage signal terminal Vfb is configured to receive a feedback voltage signal to control the Vrelay output magnitude of buck converter unit 1. The buck converter 11 itself is not the focus of this application. Known buck circuits or buck chips can be used, such as power supplies composed of commonly used buck chips like TPS5430 / L5972D, which will not be described in detail here.

[0024] Switching unit 2 includes a switching transistor Q1. The anode of switching transistor Q1 is connected to one of the voltage divider resistors in buck converter unit 1, and the cathode is grounded. Specifically, the other end of the third resistor R3 is connected in series with the anode of switching transistor Q1 and then in parallel across the second resistor R2. Therefore, when switching transistor Q1 is on, the third resistor R3 is connected to the feedback network of buck converter 11, and the voltage at the output terminal Vrelay of buck converter unit 1 is determined by the feedback voltage signal, the resistance values ​​of the first resistor R1, the second resistor R2, and the third resistor R3. When switching transistor Q1 is off, the third resistor R3 is disconnected from the feedback network, and the voltage at the output terminal Vrelay of buck converter unit 1 is determined by the feedback voltage signal, the resistance values ​​of the first resistor R1, and the second resistor R2. Theoretically, the voltage Vout at the output terminal Vrelay of Buck converter unit 1 is equal to Vfb * (1 + Ra / Rb), where Ra represents the resistance of the first resistor R1. When switch Q1 is off, resistor R3 is switched off, and Rb equals the resistance of the second resistor R2. When switch Q1 is on, Rb is the total resistance of the parallel branch formed by the first resistor R1 and the third resistor R3, i.e., Rb = R2 * R3 / (R2 + R3). Therefore, when switch Q1 is on, Rb decreases, and the output voltage Vout is higher; while when switch Q1 is off, Rb increases to R2, and the output voltage Vout decreases.

[0025] Switch Q1 includes a MOSFET, with its source grounded. Specifically, switch Q1 includes a depletion-mode N-MOSFET, with its drain connected to the third resistor R3 and its source grounded. Switch Q1 is configured to be in the ON state when a low-level signal is applied to the drive signal input terminal Dr_rly, and in the OFF state when a high-level signal is applied to the drive signal input terminal Dr_rly and the capacitor voltage is charged to the threshold voltage of switch Q1.

[0026] Switching unit 2 also includes a charging resistor R5 and a capacitor C1. One end of the charging resistor R5 is connected to the drive signal input terminal Dr_rly, and the other end is connected to the gate of the switching transistor Q1. One end of the capacitor C1 is connected to the junction of the gate of the switching transistor Q1 and the charging resistor R5, and the other end is grounded. The charging resistor R5 and the capacitor C1 constitute an RC charging circuit.

[0027] The switching unit 2 also includes a pull-down resistor R4. One end of the pull-down resistor R4 is connected to the junction point between the gate of the switching transistor Q1 and the capacitor C1, and the other end is grounded. The pull-down resistor R4 is also used to discharge the capacitor C1.

[0028] A signal isolation diode D1 is connected between switching unit 2 and the drive signal input terminal Dr_rly to prevent the resistance after the cathode of signal isolation diode D1 from affecting the relay drive unit. The positive terminal of signal isolation diode D1 is connected to the drive signal input terminal Dr_rly, and the negative terminal is connected to the charging resistor R5 of switching unit 2.

[0029] The relay drive unit 3 includes a relay drive coil, control circuit, etc. When a high-level signal is received from the drive signal input terminal Dr_rly, the control circuit responds to the high-level signal by applying the output voltage of the buck converter unit 1 to both sides of the drive coil, causing the relay contacts to close. The relay drive unit 3 is not the focus of this application and can use known relay drive circuits, which will not be described in detail here.

[0030] The driving process of the relay driving circuit in the embodiment is as follows: Before the signal input to the drive signal input terminal Dr_rly is low and the drive relay is not enabled, the switch Q1 is turned on, and the output voltage of the buck converter unit 1 is relatively high, namely Vrelay1. After the signal input to the drive signal input terminal Dr_rly is high, enabling the relay to drive, the relay is immediately driven. The buck converter unit 1 supplies power to the relay drive unit 3 with voltage Vrelay1. Simultaneously, after Dr_rly is high, it charges capacitor C1 through signal isolation diode D1D1 and charging resistor R5. When the voltage Vgate at capacitor C1 reaches the threshold voltage of switching transistor Q1, Q1 is turned off. Then, the third resistor R3 is disconnected from the original feedback network. This causes the buck converter unit 1 to switch back to adjusting the output voltage Vrelay, reducing it to Vrelay2. This achieves initial high-voltage connection and low-voltage maintenance of the relay circuit.

[0031] Simulation example: Buck converter unit 1 uses buck chips such as TPS5430 / L5972D.

[0032] The drive signal input terminal Dr_rly is a high-level signal (3.3V, e.g.) Figure 3 (As shown by the red curve in the lower middle section) After that, the relay is connected, and the drive voltage output by buck converter unit 1 is Vrelay1 (which is 12V, as shown in the image). Figure 3 As shown by the upper red curve), after a period of time, delta T ( Figure 3 Between the two leftmost vertical dashed lines (approximately 0.3 seconds), the voltage Vgate of capacitor C1 is charged up to the gate voltage 2V of switching transistor Q1 (e.g., Figure 3 (As shown by the lower blue curve) Above this point, switch Q1 is turned off, and the output voltage of buck converter unit 1 drops to Vrelay2 (which is 6V, as shown above). Figure 3 (As shown by the red curve at the top), maintain the low voltage of the relay to reduce heat loss and the temperature of the relay coil.

[0033] The embodiment utilizes the delay of RC charging to control the output voltage adjustment of buck converter 11, which is simple, reliable, and low-cost. Only a single drive signal is used to achieve the power switching between high-voltage connection and low-voltage holding of the relay.

[0034] As indicated in this specification and claims, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, and these steps and elements do not constitute an exclusive list; the method or apparatus may also include other steps or elements. The term "and / or" as used herein includes any combination of one or more of the associated listed items.

[0035] It can be further understood that in this disclosure, "multiple" refers to two or more, and other quantifiers are similar.

[0036] It should be noted that, unless otherwise specified, when a feature is referred to as "connected" to another feature, it can be directly connected to the other feature or indirectly connected to the other feature.

[0037] The above embodiments are only for illustrating the technical concept and features of this utility model, and are preferred embodiments. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it accordingly, and should not be construed as limiting the protection scope of this utility model. All equivalent transformations or modifications made based on the principles of this utility model should be covered within the protection scope of this utility model.

Claims

1. A relay drive circuit capable of buck-voltage holding, comprising a buck converter unit and a switching unit, the buck converter unit having an output terminal configured to supply power to a relay drive unit, and the switching unit having a drive signal input terminal configured to receive a relay drive signal; Its features are, The switching unit includes a charging resistor, a capacitor, and a switching transistor; one end of the charging resistor is connected to the drive signal input terminal, and the other end is connected to the gate of the switching transistor; one end of the capacitor is connected to the connection point between the gate of the switching transistor and the charging resistor, and the other end is grounded; the anode of the switching transistor is connected to the buck converter unit, and the cathode is grounded.

2. The relay drive circuit capable of voltage reduction and retention according to claim 1, characterized in that, The buck converter unit includes multiple voltage divider resistors, and the anode of the switching transistor is connected in series with one of the voltage divider resistors.

3. The relay drive circuit capable of voltage reduction and retention according to claim 2, characterized in that, The plurality of voltage divider resistors include a first resistor, a second resistor, and a third resistor, wherein the first resistor and the second resistor are connected in series with each other; one end of the third resistor is connected to the connection point of the first resistor and the second resistor, and the other end of the third resistor is connected in series with the anode of the switching transistor and then in parallel with both sides of the second resistor.

4. The relay drive circuit capable of voltage reduction and retention according to claim 3, characterized in that, The output terminal of the buck converter of the buck converter unit is connected to the connection point of the first resistor and the second resistor; the buck converter unit also has a feedback voltage signal terminal configured to receive a feedback voltage signal, the feedback voltage signal terminal being connected to the connection point of the first resistor and the second resistor.

5. The relay drive circuit capable of voltage reduction and retention according to claim 3, characterized in that, The switching transistor includes a depletion-type N-MOS transistor, the drain of which is connected to the third resistor, and the source is grounded.

6. The relay drive circuit capable of voltage reduction and holding according to claim 1, characterized in that, The switching transistor is configured to be in a conducting state when a low-level signal is received at the drive signal input terminal, and in a disconnected state when a high-level signal is received at the drive signal input terminal and the voltage of the capacitor is charged to the threshold voltage of the switching transistor.

7. The relay drive circuit capable of voltage reduction and retention according to claim 6, characterized in that, The switching transistor includes a MOSFET, and the source of the MOSFET is grounded.

8. The relay drive circuit capable of voltage reduction and retention according to claim 1, characterized in that, The switching unit further includes a pull-down resistor, one end of which is connected to the junction point between the gate of the switching transistor and the capacitor, and the other end is grounded.

9. The relay drive circuit capable of voltage reduction and retention according to claim 1, characterized in that, A signal isolation diode is connected between the switching unit and the drive signal input terminal. The positive terminal of the signal isolation diode is connected to the drive signal input terminal, and the negative terminal is connected to the charging resistor of the switching unit.

10. The relay drive circuit capable of voltage reduction and retention according to claim 1, characterized in that, The drive signal input terminal is also connected to the relay drive unit.

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