阅读说明：本技术 一种驱动继电器快速通断的控制电路 (Control circuit for driving relay to be switched on and off rapidly ) 是由 房占凯 徐光健 杨自清 陈果 方浩 马辉 刘霜 于 2020-07-23 设计创作，主要内容包括：一种驱动继电器快速通断的控制电路,包括继电器,继电器的线圈第一节点通过升压电路连接电源,继电器的线圈第二节点通过开关控制电路接收继电器驱动信号,升压电路包括PNP型三极管、第一电阻、第二电阻、储能电容、第一二极管,PNP型三极管的发射极、第一二极管的正极与电源连接,PNP型三极管的基极经第一电阻与电源连接,PNP型三极管的集电极、储能电容的负极经第三电阻接地,第一二极管的负极、储能电容的正极连接继电器的线圈第一节点,开关控制电路包括NPN型三极管、第四电阻,PNP型三极管的基极经第二电阻、稳压管连接NPN型三极管的集电极、继电器的线圈第二节点,NPN型三极管的基极经第四电阻接收继电器驱动信号,NPN型三极管的发射极接地。(A control circuit for driving a relay to be rapidly switched on and off comprises the relay, wherein a first coil node of the relay is connected with a power supply through a boost circuit, a second coil node of the relay receives a relay driving signal through a switch control circuit, the boost circuit comprises a PNP type triode, a first resistor, a second resistor, an energy storage capacitor and a first diode, an emitting electrode of the PNP type triode and an anode of the first diode are connected with the power supply, a base electrode of the PNP type triode is connected with the power supply through the first resistor, a collector electrode of the PNP type triode and a cathode of the energy storage capacitor are grounded through a third resistor, a cathode of the first diode and an anode of the energy storage capacitor are connected with the first coil node of the relay, the switch control circuit comprises an NPN type triode and a fourth resistor, a base electrode of the PNP type triode is connected with a collector electrode of the NPN type triode and a second coil node, the base electrode of the NPN type triode receives the relay driving signal through the fourth resistor, and the emitting electrode of the NPN type triode is grounded.)

1. The utility model provides a control circuit of quick break-make of drive relay, includes the relay, its characterized in that: the first node of the coil of the relay is connected with a power supply through a booster circuit, the second node of the coil of the relay receives a relay driving signal through a switch control circuit, the booster circuit comprises a PNP type triode, a first resistor, a second resistor, an energy storage capacitor and a first diode, the emitting electrode of the PNP type triode and the anode of the first diode are connected with the power supply, the base electrode of the PNP type triode is connected with the power supply through the first resistor, the collector electrode of the PNP type triode and the cathode of the energy storage capacitor are grounded through a third resistor, the cathode of the first diode and the anode of the energy storage capacitor are connected with the first node of the coil of the relay, the base electrode of the PNP type triode is connected with the switch control circuit through the second resistor and a voltage stabilizing tube in sequence, the switch control circuit comprises an NPN type triode and a fourth resistor, the collector electrode of the NPN type triode is, And a coil second node of the relay and a base electrode of the NPN type triode receive a relay driving signal through a fourth resistor, and an emitting electrode of the NPN type triode is grounded.

2. The control circuit for driving the relay to be rapidly switched on and switched off according to claim 1, wherein: the first diode adopts a Schottky diode.

3. The control circuit for driving the relay to be rapidly switched on and switched off according to claim 1, wherein: and a second diode is connected between the collector and the emitter of the NPN type triode in parallel, the anode of the second diode is connected with the emitter of the NPN type triode, and the cathode of the second diode is connected with the collector of the NPN type triode.

4. The control circuit for driving the relay to be rapidly switched on and switched off according to claim 1, wherein: the energy storage capacitor is an electrolytic capacitor.

5. The control circuit for driving the relay to be rapidly switched on and switched off according to claim 1, wherein: the NPN type triode can adopt an N type field effect transistor, the grid electrode of the N type field effect transistor is connected with a relay driving signal, the drain electrode of the N type field effect transistor is connected with a second node of a coil of the relay, and the source electrode of the N type field effect transistor is grounded.

6. The control circuit for driving the relay to be rapidly switched on and switched off according to claim 1, wherein: an RC filter circuit is connected between the base electrode of the NPN type triode and the ground in parallel, and the RC filter circuit is composed of a fifth resistor and a second capacitor which are connected in parallel.

Technical Field

The invention relates to the technical field of relay drive control, in particular to a control circuit for driving a relay to be rapidly switched on and switched off.

Background

Relays play an important role in daily life and various industries, such as card-insertion power-taking switches and touch doorbells in life, driving of shielded doors in rail transit, low-voltage low-current control high-voltage high-current in power equipment, pre-charging protection of frequency converters and active power filter circuits and the like. The relay is composed of a coil and a contact, and has two working states of opening and closing, when the relay is opened, a higher voltage is needed to provide enough energy for the contact attraction in the contact attraction process, and the contact can be kept in the attraction state only by a lower voltage after the contact attraction, if the relay is reliably opened, the high voltage is always kept during and after the contact attraction, so that the coil of the relay is easy to generate heat seriously, and the relay is damaged. For this situation, the currently common solutions are as follows:

the method comprises the following steps: as shown in fig. 3, by using the principle of short follow current pull-in and hold of the coil when the relay is closed, the relay can be reliably pulled in through the high level lasting for several seconds when the relay is pulled in, and after the relay is pulled in, the relay is driven by PWM, and when the PWM wave is in the valley, the relay still keeps the pull-in state by the follow current characteristic of the coil. Although the method can reduce the heating of the coil of the relay and does not need to use double voltages, diodes need to be connected in parallel at two ends of the relay, the relay is easy to turn off and delay, if the relay cannot be turned off rapidly when equipment fails, the equipment is easy to damage, and when the relay is controlled to be turned on and turned off by adopting PWM, the driving time of high and low levels of PWM waveforms needs to be the same, so the normal driving time is longer, and the waveform requirement on PWM driving signals is higher.

The second method comprises the following steps: as shown in fig. 4, in the dual-voltage driving mode, the high driving voltage VH is connected to the energy storage capacitor C4 through the current limiting resistor R8, and the low driving voltage VL is connected to the energy storage capacitor C4 through the diode D5. When the relay does not work, the high driving voltage VH charges an energy storage capacitor C4, and sufficient voltage can drive the contact of the relay to pull in; after the relay is pulled in, the relay is stopped to be driven by the high driving voltage VH under the action of the current-limiting resistor R8, and the relay is continuously supplied with power by the low driving voltage VL, so that the heating condition of a relay coil is reduced, but the mode needs double power supplies and has higher requirements on a power supply.

Disclosure of Invention

The invention aims to provide a control circuit for driving a relay to be rapidly switched on and off aiming at the defects of the prior art, which can realize rapid switching on and rapid switching off of the relay, and reduce the coil loss and the coil heating of the relay.

The technical scheme of the invention is as follows: a control circuit for driving a relay to be switched on and off rapidly comprises the relay, wherein a first coil node of the relay is connected with a power supply through a boost circuit, a second coil node of the relay receives a relay driving signal through a switch control circuit, the boost circuit comprises a PNP type triode, a first resistor, a second resistor, an energy storage capacitor and a first diode, an emitting electrode of the PNP type triode and an anode of the first diode are connected with the power supply, a base electrode of the PNP type triode is connected with the power supply through the first resistor, a collector electrode of the PNP type triode and a cathode of the energy storage capacitor are grounded through a third resistor, a cathode of the first diode and an anode of the energy storage capacitor are connected with the first coil node of the relay, the base electrode of the PNP type triode is sequentially connected with the switch control circuit through the second resistor and a voltage stabilizing tube, and the switch control circuit comprises an NPN type triode and a, and the collector of the NPN type triode is respectively connected with the negative electrode of the voltage regulator tube and the second node of the coil of the relay, the base of the NPN type triode receives a relay driving signal through a fourth resistor, and the emitter of the NPN type triode is grounded.

The first diode adopts a Schottky diode.

And a second diode is connected between the collector and the emitter of the NPN type triode in parallel, the anode of the second diode is connected with the emitter of the NPN type triode, and the cathode of the second diode is connected with the collector of the NPN type triode.

The energy storage capacitor is an electrolytic capacitor.

The NPN type triode can adopt an N type field effect transistor, the grid electrode of the N type field effect transistor is connected with a relay driving signal, the drain electrode of the N type field effect transistor is connected with a second node of a coil of the relay, and the source electrode of the N type field effect transistor is grounded.

An RC filter circuit is connected between the base electrode of the NPN type triode and the ground in parallel, and the RC filter circuit is composed of a fifth resistor and a second capacitor which are connected in parallel.

Adopt above-mentioned technical scheme: a first node of a coil of the relay is connected with a power supply through a booster circuit, and a second node of the coil of the relay receives a relay driving signal through a switch control circuit, namely, the on and off of the relay are realized through the two circuits. The booster circuit comprises a PNP type triode, a first resistor, a second resistor, an energy storage capacitor and a first diode, wherein an emitting electrode of the PNP type triode and an anode of the first diode are connected with a power supply, a base electrode of the PNP type triode is connected with the power supply through the first resistor, a collector electrode of the PNP type triode and a cathode of the energy storage capacitor are grounded through a third resistor, a cathode of the first diode and an anode of the energy storage capacitor are connected with a first coil node of the relay, the energy storage capacitor can be charged through the booster circuit, enough energy is reserved for opening the relay, and the relay is kept in an opening state by low voltage after the relay is opened. The base electrode of the PNP type triode is connected with a switch control circuit through a second resistor and a voltage stabilizing tube in sequence, the switch control circuit comprises an NPN type triode and a fourth resistor, the collector electrode of the NPN type triode is respectively connected with the negative electrode of the voltage stabilizing tube and the coil second node of the relay, the base electrode of the NPN type triode receives a relay driving signal through the fourth resistor, the emitter electrode of the NPN type triode is grounded, the switch control circuit controls the on and off of the relay through receiving the relay driving signal, because the NPN type triode is adopted, when the relay driving signal is low level, the NPN type triode is turned off, the energy storage capacitor is charged through the boosting circuit, when the relay driving signal is high level, the NPN type triode is turned on, the instantaneous voltage of the coil first node of the relay rises, so that the relay is turned on rapidly, and the voltage of the coil first node falls simultaneously after the relay is turned on, the relay is kept in an on state under a small voltage. When the relay driving signal is converted from high level to low level, the NPN type triode is turned off, the relay is also turned off, and the voltage stabilizing tube is connected between the second resistor and the second node of the coil of the relay and can block the follow current function of the coil when the relay is turned off, so that the turn-off of the relay is accelerated. Therefore, the control circuit can realize the rapid switching-on and switching-off of the relay, and after the relay is driven to be switched on by high voltage, the relay can be kept in a switching-on state under low voltage, the coil loss and the heating condition of the relay are reduced, the impact of the reverse electromotive force on the NPN type triode when the relay is switched off can be prevented, and the circuit device is protected.

The first diode adopts a Schottky diode, the switching speed is high, when the coil of the relay is powered off, a follow current channel can be quickly established, and the phenomenon that the overhigh reverse electromotive force of the coil impacts the NPN type triode is prevented.

And a second diode is connected between the collector and the emitter of the NPN type triode in parallel, the anode of the second diode is connected with the emitter of the NPN type triode, and the cathode of the second diode is connected with the collector of the NPN type triode, so that the reverse conduction of the NPN type triode is avoided, and the effect of protecting a circuit device is achieved.

An RC filter circuit is connected between the base electrode of the NPN type triode and the ground in parallel, and the RC filter circuit is composed of a fifth resistor and a second capacitor which are connected in parallel and plays a role in filtering a relay driving signal.

The invention is further described with reference to the drawings and the specific embodiments in the following description.

Drawings

FIG. 1 is a schematic circuit diagram of the present invention;

FIG. 2 is a circuit schematic of an embodiment of the present invention;

FIG. 3 is a schematic circuit diagram of a prior art PWM driven relay;

fig. 4 is a schematic circuit diagram of a conventional dual voltage driven relay.

Detailed Description

Referring to fig. 1 to 2, a control circuit for driving a relay to be switched on and off rapidly comprises a relay Y1, a first node of a coil of the relay Y1 is connected with a power supply through a boost circuit, and a second node of a coil of the relay Y1 receives a relay driving signal through a switch control circuit, namely, the boost circuit and the switch control circuit jointly realize the on and off of the relay Y1. The boosting circuit comprises a PNP type triode Q1, an energy storage capacitor C1, a first diode D1, a first resistor R1 and a second resistor R2 which are used for voltage division, an emitter of the PNP type triode Q1 and a positive electrode of a first diode D1 are connected with a power supply, a base of the PNP type triode Q1 is connected with the power supply through a first resistor R1, a collector of the PNP type triode Q1 and a negative electrode of an energy storage capacitor C1 are grounded through a third resistor R3, the third resistor R3 plays a role in limiting current for the PNP type triode Q1, the PNP type triode Q1 is prevented from being damaged due to overlarge current, a negative electrode of the first diode D1 and a positive electrode of the energy storage capacitor C1 are connected with a first node of a coil of a relay Y1, a base of the PNP type triode Q1 is connected with a switch control circuit through the second resistor R2 and a voltage regulator D3 in sequence, and the PNP type triode Q1 can be conducted with the first diode Q1 through the first resistor R1 and the PNP type triode Q1, Energy storage capacitor C1 cooperates and realizes the bootstrap boost function to improve the instantaneous voltage on the coil first node of relay Y1, consequently can charge energy storage capacitor C1 through this boost circuit, for opening enough big energy of relay Y1 deposit, realize that high voltage drive relay Y1 opens, and turn to by the on-state of low-voltage maintenance relay Y1 after relay Y1 opens. The energy storage capacitor C1 is an electrolytic capacitor, has large capacity and high rated withstand voltage value, and can adopt an aluminum electrolytic capacitor with lower price to reduce the cost of devices.

The switch control circuit comprises an NPN type triode Q2 and a fourth resistor R4 used for limiting current, wherein a collector of the NPN type triode Q2 is respectively connected with a negative electrode of a voltage regulator tube D3 and a second node of a coil of a relay Y1, a positive electrode of the voltage regulator tube D3 is connected with a second resistor R2, a base electrode of the NPN type triode Q2 receives a driving signal of the relay Y1 through the fourth resistor R4, and an emitting electrode of the NPN type triode Q2 is grounded. The switch control circuit controls the on and off of the relay Y1 by receiving a relay Y1 driving signal, because the NPN transistor Q2 is used, when the relay drive signal is low, the NPN type triode Q2 and the PNP type triode Q1 are both in an off state, a power supply in the booster circuit charges an energy storage capacitor C1 through a first diode D1, so that the energy storage capacitor C1 stores enough voltage for turning on a relay Y1, when the relay driving signal is high level, the NPN type triode Q2 and the PNP type triode Q1 are both in an on state, the instantaneous voltage on the first node of the coil of the relay Y1 rises to meet the high driving voltage required by the relay Y1, so that the relay Y1 is rapidly turned on, when the relay Y1 is turned on, the voltage at the first node of the coil of the relay Y1 is lowered synchronously, and the relay Y1 is kept in the on state by the low voltage. When the relay driving signal is converted from high level to low level, the NPN type triode Q2 is turned off, the relay Y1 is also turned off, because the coil of the relay Y1 is equivalent to a large inductor, reverse voltage can be induced during the turn-off, in order to prevent the overhigh reverse electromotive force of the coil of the relay Y1 from impacting the NPN type triode Q2, the first diode D1 adopts a Schottky diode, the switching speed is high, and when the coil of the relay Y1 is powered off, a follow current channel can be quickly established. And in addition, a voltage regulator tube D3 is connected between the second resistor R2 and the second node of the coil of the relay Y1, so that when the relay Y1 is turned off, the voltage regulator tube D3 can block the follow current function of the coil of the relay Y1, the turn-off of the relay Y1 is accelerated, and the purpose of quickly turning off the relay Y1 is achieved.

A second diode D2 is connected in parallel between the collector and the emitter of the NPN type triode Q2, the anode of the second diode D2 is connected with the emitter of the NPN type triode Q2, and the cathode of the second diode D2 is connected with the collector of the NPN type triode Q2, so that reverse conduction of the NPN type triode Q2 is avoided, and a circuit device is protected. The NPN type triode Q2 can also adopt an N type field effect transistor, the grid electrode of the N type field effect transistor is connected with a driving signal of the relay Y1, the drain electrode of the N type field effect transistor is connected with the second node of the coil of the relay Y1, and the source electrode of the N type field effect transistor is grounded.

An RC filter circuit is connected in parallel between the base of the NPN type triode Q2 and the ground, the RC filter circuit is composed of a fifth resistor R5 and a second capacitor C2 which are connected in parallel, the RC filter circuit has a filtering effect on a driving signal of a relay Y1, and the driving signal of the relay Y1 is divided through the fifth resistor R5 and a fourth resistor R4, so that the base voltage of the NPN type triode Q2 meets the conditions of turning on and turning off.

In the present embodiment, a specific analysis is performed on the control circuit by taking relay Y1 with a rated voltage of 24V, a switching current of 30A, a coil resistance of 200 Ω, and a release voltage of 2.4V as an example. And based on the parameters of relay Y1, the other circuit components are designed as follows.

A24V power supply is selected, and the high level of a relay driving signal is designed to be 15V, and the low level is designed to be 0.

In the switch control circuit, in order to prevent the NPN triode Q2 from being damaged by the impact of the reverse electromotive force after the coil of the relay Y1 is powered off, the NPN triode Q2 is made of TIP41C with high withstand voltage, namely, each parameter of the NPN triode Q2 is I_CM=10A，V_CE=1.2V，V_BE=1.8V，V_CEO=V_CBO= 100V. The second diode D2 is a normal diode 1N 4148. According to an NPN type triode Q2, a fourth resistor R4 with the resistance of 2k omega is selected, the resistance of a fifth resistor R5 is 50k omega, and a second capacitor C2 is a capacitor with the withstand voltage of 63V and the capacitance of 0.1 uF.

In the boost circuit, because the capacitance value of the energy storage capacitor C1 is larger, the relay Y1 can make the high voltage maintain longer when being turned on, and the relay Y1 is more easily turned on, but if the relay Y1 is frequently turned on and off, the energy storage capacitor C1 cannot be guaranteed to have enough charging time, so that the subsequent quick turn-on of the relay Y1 is difficult to guarantee, and the larger the capacitance value is, the higher the cost of the energy storage capacitor C1 is, therefore, according to the practical situation, the electrolytic capacitor with the capacitance value of 47uF and withstand voltage of 50V is selected for use in the embodiment. The model of the PNP type triode Q1 is 2N4920, namely, each parameter of the PNP type triode Q1 isI_CM=3A，V_CE=0.6V，V_BE=1.3V，V_CEO=V_CBO= 80V. The first diode D1 is a Schottky diode of MUR120 type, i.e., the first diode D1 has parameters of 200V maximum reverse surge voltage, 1A average current, and V forward voltage drop_FM= 0.875V. The resistance value of the third resistor R3 for limiting current is selected to be 10k Ω. For the selection of the first resistor R1 and the second resistor R2, if the resistance values of the first resistor R1 and the second resistor R2 are too large, the current generated when the coil of the relay Y1 is powered off cannot rapidly form a follow current through the voltage regulator D3, the first resistor R1, the second resistor R2 and the first diode D1, at this time, although the relay Y1 is rapidly disconnected, the reverse electromotive force generated by the coil of the relay Y1 is very large, which may cause the NPN type triode Q2 to be damaged, and if the resistance values of the two resistors are too small, the follow current is accelerated, which may cause the disconnection time of the coil to be prolonged, and at this time, the current is too large, which may also damage the NPN type triode Q2, so the resistance values selected by the first resistor R1 and the second resistor R2. The model of the voltage-stabilizing tube D3 is BZX84C16, and the voltage-stabilizing voltage is 16V.

The specific working flow of the control circuit of the embodiment is as follows:

when the relay is initially powered on, when the relay driving signal is at a low level, the NPN type transistor Q2 is turned off, the relay is in an off state, the PNP type transistor Q1 is also in an off state because the base voltage is about 24V, and the power supply charges the energy storage capacitor C1 through the first diode D1, so that the voltage of the energy storage capacitor is increased from 0 to about 24V-0.875V =23.125V, and the relay storage voltage is turned on.

When the relay driving signal is changed from low level to high level, the NPN type transistor Q2 is turned on, the voltage of the second node of the coil of the relay is about 1.2V, and the voltage of the base of the PNP type transistor Q1 is about 24- (24-0.7-1.2)/2=13V, as shown in I2 in fig. 2, at this time, the PNP type transistor Q1 is turned on, the voltage of the first node of the coil of the relay is instantaneously raised to 24-1.3+23.125=45.8V, so that the relay is driven to be turned on by high voltage, and after the relay is turned on, the voltage of the first node of the coil of the relay is lowered from 45.8V to 23.125V, that is, the relay is kept in a stable on state by low voltage, as shown in I1 in fig. 2.

When the relay driving signal changes from high level to low level, the NPN transistor Q2 turns off, because the coil of the relay is large inductance, the coil can induce reverse electromotive force, so as to form follow current with the voltage regulator tube D3, the first resistor R1, the second resistor R2 and the first diode D1, as shown in I3 in figure 4, because the blocking voltage of the voltage regulator tube D3 is 16V, the free-wheeling state can be entered only when the reverse voltage induced by the coil of the relay is larger than the blocking voltage 16V, therefore, the voltage regulator tube D3, the first resistor R1 and the second resistor R2 are used for blocking the follow current of the relay coil, when the voltage of the relay Y1 is more than 16V, because the first diode D1 adopts schottky diode, it can form free flow rapidly, avoid impact of reverse voltage to the NPN type triode Q2, the switch-off is achieved when the voltage of the relay coil drops to 16V, thereby speeding up the closing of relay Y1.

The analysis shows that the control circuit realizes the rapid switching-on and switching-off of the relay through the matching of the booster circuit and the switch control circuit, and after the relay is driven to be switched on by high voltage, the relay can be kept in a switching-on state under low voltage, the coil loss and the heating condition of the relay are reduced, the impact of the reverse electromotive force generated when the relay Y1 is switched off on the NPN type triode Q2 can be prevented, and the circuit device is protected.