阅读说明：本技术 一种继电器驱动电路 (Relay drive circuit ) 是由 余仕君 崔彬 胡小明 肖旭潘 于 2021-09-13 设计创作，主要内容包括：本发明提供了一种继电器驱动电路,包括电源Vcc、驱动信号输入端、辅助开关电路、主开关电路、储能电容C1、二极管D1及继电器Relay；本发明提出的继电器驱动电路中所需供电电源只有一个,与背景技术中提出的继电器驱动电路相比,本驱动电路减少了一些开关管、二极管及电阻、储能电容等器件,电源Vcc和储能电容C1为继电器线圈提供高平台驱动电压,而电源Vcc为继电器线圈提供低平台驱动电压,其中,驱动电路不会因额外的电源需求而增加额外的损耗,同时因为继电器线圈驱动电路所需器件较少而降低成本,减少单板尺寸,提高功率密度。(The invention provides a Relay drive circuit, which comprises a power supply Vcc, a drive signal input end, an auxiliary switch circuit, a main switch circuit, an energy storage capacitor C1, a diode D1 and a Relay; compared with the relay drive circuit provided by the background technology, the relay drive circuit provided by the invention has the advantages that only one power supply is needed, and the number of switching tubes, diodes, resistors, energy storage capacitors and other devices is reduced, the power supply Vcc and the energy storage capacitor C1 provide high platform drive voltage for the relay coil, and the power supply Vcc provides low platform drive voltage for the relay coil, wherein the drive circuit does not increase extra loss due to extra power supply requirements, and meanwhile, the cost is reduced due to the fact that fewer devices are needed by the relay coil drive circuit, the size of a single board is reduced, and the power density is improved.)

1. A Relay drive circuit is characterized by comprising a power supply Vcc, a drive signal input end, an auxiliary switch circuit, a main switch circuit, an energy storage capacitor C1, a diode D1 and a Relay; the driving signal input end is connected with the auxiliary switch circuit and used for inputting a driving signal Relay _ DR to control the on/off of the auxiliary switch circuit, one end node of the energy storage capacitor C1 is divided into two paths, the first path is connected with the power supply Vcc through the diode D1, the second path is connected with one end of the Relay coil, the other end node of the energy storage capacitor C1 is divided into two paths, the first path is connected with the auxiliary switch circuit, and the second path is connected with the other end of the Relay coil through the main switch circuit.

2. The relay driver circuit according to claim 1, wherein the auxiliary switch circuit comprises an NPN transistor Q1 and a PNP transistor Q2, a collector of the transistor Q1 is connected to the power Vcc, an emitter of the transistor Q1 is connected to an emitter of the transistor Q2, and a collector of the transistor Q2 is grounded.

3. The relay driver circuit according to claim 1, wherein the auxiliary switch circuit is an integrated chip, and the integrated chip is configured to provide a driving voltage for the main switch circuit and a charging and discharging loop for the energy storage capacitor C1.

4. The relay driver circuit according to claim 2, wherein the driving signal input terminal of the driver circuit is divided into two paths by a resistor R1, the first path is connected to the base of the transistor Q1, and the second path is connected to the base of the transistor Q2.

5. The relay driver circuit according to claim 4, wherein the main switch circuit comprises a MOS transistor Q3, the drain of the MOS transistor Q3 is connected to the other end of the relay coil, the source of the MOS transistor Q3 is grounded, and the gate of the MOS transistor Q3 is connected to the emitter of the transistor Q1 and one end of the energy storage capacitor C1.

6. The relay driving circuit according to claim 5, wherein the main switching circuit further comprises a resistor R4, a resistor R5, a voltage regulator tube D2; the resistor R4 is connected to the node at the other end of the C1 and connected to the source electrode of the MOS transistor Q3, the resistor R5 is connected between the energy storage capacitor C1 and the grid electrode of the MOS transistor Q3, the anode of the voltage regulator D2 is connected to the source electrode of the MOS transistor Q3, and the cathode of the voltage regulator D2 is connected to the drain electrode of the MOS transistor Q3.

7. The relay driver circuit according to claim 6, wherein the resistor R5 is connected between the emitter of the transistor Q1 and the energy storage capacitor C1.

8. The relay driver circuit as claimed in claim 7, further comprising a resistor R3, wherein the emitter of the transistor Q2 is connected to one end of the energy storage capacitor C1 through the resistor R3.

Technical Field

The invention belongs to the technical field of power electronics, and particularly relates to a relay drive circuit.

Background

With the higher and higher requirements of the market on the product efficiency, the driving loss of the relay of the product is more and more emphasized, and the reduction of the driving loss of the relay becomes a means for improving the efficiency of most manufacturers.

At present, the low-loss relay driving mode is roughly divided into the following two modes, one mode is pulse type driving, namely the driving waveform of the relay is a pulse signal with the duty ratio of about 50 percent; one is variable voltage drive, i.e. the voltage at the moment of relay pull-in is higher Vcc1, and the relay pull-in sustain voltage is lower Vcc 2.

From the above analysis, it can be seen that 2 power supplies are required in the voltage-variable driving, and the provision of additional power supplies results in reduced efficiency and increased cost, and the number of components required for the relay driving circuit is increased, which also results in increased cost and increased circuit board size.

Disclosure of Invention

The invention aims to provide a relay drive circuit, and aims to solve the problems of more required devices, large circuit board size and increased drive cost in the traditional relay drive circuit.

In order to solve the technical problem, the invention is realized in such a way that a Relay driving circuit comprises a power supply Vcc, a driving signal input end, an auxiliary switch circuit, a main switch circuit, an energy storage capacitor C1, a diode D1 and a Relay; the driving signal input end is connected with the auxiliary switch circuit and used for inputting a driving signal Relay _ DR to control the on/off of the auxiliary switch circuit, one end node of the energy storage capacitor C1 is divided into two paths, the first path is connected with the power supply Vcc through the diode D1, the second path is connected with one end of the Relay coil, the other end node of the energy storage capacitor C1 is divided into two paths, the first path is connected with the auxiliary switch circuit, and the second path is connected with the other end of the Relay coil through the main switch circuit.

Preferably, the auxiliary switch circuit is composed of components and devices, and includes an NPN transistor Q1 and a PNP transistor Q2, a collector of the transistor Q1 is connected to the power Vcc, an emitter of the transistor Q1 is connected to an emitter of the transistor Q2, and a collector of the transistor Q2 is grounded.

Preferably, the auxiliary switch circuit is an integrated chip, and the integrated chip is configured to provide a driving voltage for the main switch circuit and provide a charge-discharge loop for the energy storage capacitor C1.

Preferably, a driving signal input terminal Relay _ DR of the driving circuit is divided into two paths by a resistor R1, the first path is connected with a base of the triode Q1, and the second path is connected with a base of the triode Q2.

Preferably, the main switch circuit includes a MOS transistor Q3, a drain of the MOS transistor Q3 is connected to the other end of the relay coil, a source of the MOS transistor Q3 is grounded, and a gate of the MOS transistor Q3 is connected to an emitter of the transistor Q1 and one end of the energy storage capacitor C1.

Preferably, the main switch circuit further comprises a resistor R4, a resistor R5, and a voltage regulator tube D2; the resistor R4 is connected to the node at the other end of the C1 and connected to the source electrode of the MOS transistor Q3, the resistor R5 is connected between the energy storage capacitor C1 and the grid electrode of the MOS transistor Q3, the anode of the voltage regulator D2 is connected to the source electrode of the MOS transistor Q3, and the cathode of the voltage regulator D2 is connected to the drain electrode of the MOS transistor Q3.

Preferably, the resistor R5 is connected between the emitter of the transistor Q1 and the energy storage capacitor C1.

Preferably, the relay driving circuit further includes a resistor R3, and an emitter of the transistor Q2 is connected to one end of the energy storage capacitor C1 through the resistor R3.

Compared with the related technology, the relay driving circuit has the advantages that: the relay driving circuit provided by the invention needs only one power supply, so that devices such as a switch tube, a diode, a resistor, an energy storage capacitor and the like are reduced, the power supply Vcc and the energy storage capacitor C1 provide high platform driving voltage for the relay coil, the power supply Vcc provides low platform driving voltage for the relay coil, the driving circuit does not increase extra loss due to extra power supply requirements, meanwhile, the cost is reduced due to fewer devices needed by the relay coil driving circuit, the size of a single plate is reduced, and the power density is improved.

Drawings

Fig. 1 is a circuit configuration topology diagram of a related art relay drive circuit;

fig. 2 is a diagram of a drive voltage waveform of a related art relay drive circuit;

fig. 3 is a circuit configuration topology diagram of the relay drive circuit of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the related art, a voltage-variable driving principle block diagram is shown in fig. 1, Relay is driven, Q1-Q5 are switching tubes, D1 and D3 are diodes, D2 is a voltage regulator tube, C1 is a blocking capacitor, Relay _ DRV is a driving signal of the Relay, R1 and R2 are driving resistors and pull-down resistors of Q1 and Q2 tubes, R4 and R5 are driving resistors and pull-down resistors of the Q3 tube, R3 and R6 are driving resistors and pull-down resistors of the Q5 tube, and R8 and R7 are pull-up resistors and driving resistors of the Q4 tube, respectively.

The circuit operation is divided into four stages:

stage 1: when Relay _ DRV is low, Q1 is turned off, Q2 is turned on, Q3, Q4, and Q5 are turned off, the voltage across capacitor C1 is 0V, the voltage across the Relay coil is 0, and the Relay contact is turned off.

And (2) stage: when Relay _ DRV is high, Q1 is turned on, Q2 is turned off, Q3 is turned on, and meanwhile, a driving signal Relay _ DRV charges a capacitor C1 and supplies current to the base of Q5, Q5 is turned on, the voltage of the base of Q4 is pulled low, Q4 is turned on, a power supply Vcc1 supplies power to a Relay coil through Q3 and Q4, and the voltage at two ends of the Relay coil is about Vcc 1. Since the voltage of Vcc1 is greater than the voltage of Vcc2, diode D1 turns off in the reverse direction, and the relay pulls in until phase 3.

And (3) stage: when Relay _ DRV is still high, the voltage of the capacitor C1 is charged high, the current flowing through the base of Q5 is reduced to 0A, Q5 is turned off, meanwhile, the voltage of the base of Q4 is raised, Q4 is turned off, the diode D1 is naturally turned on, Vcc2 supplies power to the Relay coil through the diode D1 and the switching tube Q3, the voltage at two ends of the Relay coil is about Vcc2, and the Relay is in a low-loss pull-in holding stage at this stage.

And (4) stage: relay _ DRV goes low, Q1 is off, Q2 is on, and Q3 is off. The capacitor C1 discharges through the resistor R3 and the diode D3, and the circuit operation transitions to stage 1 after the discharge is completed.

The drive voltage waveform at the relay coil is shown in fig. 2. it can be seen from fig. 2 that there is a high voltage pull-in drive period, a low voltage pull-in hold period and a no drive period for the relay drive voltage.

From the above analysis, it can be seen that the above solution requires 2 power supplies, and providing additional power supplies will result in reduced efficiency and increased cost, and at the same time, the relay driving circuit needs more devices, which also results in increased cost and increased circuit board size.

Example (b):

the invention provides a Relay drive circuit, which comprises a power supply Vcc, a drive signal input end, an auxiliary switch circuit, a main switch circuit, an energy storage capacitor C1, a diode D1 and a Relay; the driving signal input end is connected with the auxiliary switch circuit, the driving signal input end is used for inputting a driving signal Relay _ DR to control the on/off of the auxiliary switch circuit, one end node of the energy storage capacitor C1 is divided into two paths, the first path is connected with a power supply Vcc through a diode D1, the second path is connected with one end of a Relay coil of the Relay, the other end node of the energy storage capacitor C1 is divided into two paths, the first path is connected with the auxiliary switch circuit, and the second path is connected with the other end of the Relay coil of the Relay through the main switch circuit.

The relay driving circuit provided by the invention controls each working stage of the relay through control signal input, wherein the control signal can control the on-off of each switch in the auxiliary switch circuit and the main switch circuit, the energy storage capacitor C1 can be charged through a power supply Vcc through the on-off control of each switch to form a charging loop, and in addition, based on the anode-cathode direction of the diode as the power supply Vcc-energy storage capacitor C1 direction, after the common point potential of the diode and the energy storage capacitor C1 is raised, the diode is reversely cut off to form a discharging loop of the energy storage capacitor C1.

Referring to fig. 3, fig. 3 is a circuit topology diagram of the relay driving circuit of the present invention, the auxiliary switch circuit is composed of discrete components, and includes an NPN type transistor Q1 and a PNP type transistor Q2, a collector of the transistor Q1 is connected to the power Vcc, an emitter of the transistor Q1 is connected to an emitter of the transistor Q2, and a collector of the transistor Q2 is grounded.

As one implementation of this embodiment, the auxiliary switch circuit may also be an integrated chip, such as a driver chip, where the driver chip is configured to provide a driving voltage for the main switch circuit and provide a charging and discharging loop for the energy storage capacitor C1, and the driver chip has a smaller volume and can reduce more board sizes compared to a discrete device combination.

As shown in fig. 3, the driving signal input terminal of the driving circuit is divided into two paths by a resistor R1, the first path is connected to the base of a transistor Q1, the second path is connected to the base of a transistor Q2, wherein R1 is the driving resistor of the transistor Q1, further, a pull-down resistor R2 is provided for the transistor Q2, and the resistor R2 is connected between the base and the collector of the transistor Q2.

In one embodiment of this embodiment, the main switch circuit includes a MOS transistor Q3, the drain of the MOS transistor Q3 is connected to the relay, the source of the MOS transistor Q3 is grounded, the gate of the MOS transistor Q3 is connected to the emitter of the transistor Q1 and one end of the energy storage capacitor C1, and the main switch circuit is used to provide a relay coil driving current loop.

The main switch circuit further comprises a resistor R4, a resistor R5 and a voltage regulator tube D2, wherein the resistor R4 is used as a pull-down resistor of the MOS tube Q3 and connected to the node at the other end of the C1 and connected to the source electrode of the MOS tube, the resistor R5 is used as a driving resistor of the MOS tube Q3 and connected between the energy storage capacitor C1 and the grid electrode of the MOS tube, the anode of the voltage regulator tube D2 is connected to the source electrode of the MOS tube, and the cathode of the voltage regulator tube D2 is connected to the drain electrode of the MOS tube.

As one embodiment of this embodiment, the resistor R5 may be connected between the emitter of the transistor Q1 and the energy storage capacitor C1, and simultaneously functions as a charging current limiting for the energy storage capacitor C1 and a driving resistor for the MOS transistor Q3.

It should be noted that, when the resistor R5 is disposed between the energy storage capacitor C1 and the MOS transistor Q3, a current limiting resistor of the energy storage capacitor C1 needs to be additionally disposed, specifically, the relay driving circuit further includes a resistor R3, an emitter of the transistor Q2 is connected to one end of the energy storage capacitor C1 through a resistor R3, and the current limiting resistor can be directly shorted out in an application situation where the relay coil has a small driving power.

The semiconductor devices Q1-Q3, D1-D4 in this embodiment may also be replaced by other controllable or semi-controllable devices that meet the functional requirements.

The working principle is as follows:

in fig. 3, a MOS transistor Q3 is a main switching transistor, Q1-Q2 are auxiliary switching transistors, a MOS transistor Q3 is used for providing a relay coil driving current loop, and triodes Q1-Q2 are used for providing a driving voltage for a MOS transistor Q3 and providing a charging and discharging loop for an energy storage capacitor C1.

The operation of the driving circuit can be divided into four stages:

stage 1: when the driving signal input end Relay _ DRV is low, the triode Q1 is turned off, the Q2 is turned on, the Q3 is turned off, and the voltage at two ends of the Relay coil is 0V. At this time, the energy storage capacitor C1 is charged through the resistor R3 and the diode D1 (note: the resistor R3 plays a role of charging current limiting, and the loss of the resistor R3 is small due to short charging time), and finally the voltage of the energy storage capacitor C1 is the power supply voltage Vcc.

And (2) stage: the driving signal input end Relay _ DRV becomes high, the triode Q1 is switched on, the Q2 is switched off, the main tube MOS tube Q3 is switched on, and the Relay coil drives the loop to be switched on. Because the transistor Q1 is turned on, the potential of the common point of the transistor Q1 and the transistor C1 is raised to Vcc (note: the voltage drop of the transistor Q1 is not considered during analysis), and because the voltage across the energy storage capacitor C1 cannot suddenly change, the potential of the common point of the diode D1 and the energy storage capacitor C1 is raised to 2 times the voltage of Vcc, and the diode D1 is reversely cut off. This causes a voltage across the relay coil of about 2 times the VCC voltage, at which stage the relay contacts pull in.

And (3) stage: the drive signal input terminal Relay _ DRV is still high. At this time, the voltage of the capacitor C1 drops to zero due to the discharge at the two ends, the diode D1 starts to conduct naturally and provides voltage for the relay coil, the voltage at the two ends of the relay coil is Vcc at this time, and the relay is in the pull-in holding stage at this stage.

And (4) stage: the driving signal input terminal Relay _ DRV goes low, the transistors Q1, Q3 are turned off, and Q2 is turned on. The circuit operation transitions to phase 1.

From the analysis, only one power supply is needed in the relay driving circuit provided by the invention, and compared with the relay driving circuit in the related technology, the relay driving circuit reduces some devices such as a switch tube, a diode, a resistance capacitor and the like; the power supply Vcc and the energy storage capacitor C1 provide a high platform drive voltage for the relay coil, while Vcc provides a low platform drive voltage for the relay coil; the driving circuit does not increase extra loss due to extra power supply requirements, and meanwhile, the cost is reduced due to fewer devices required by the relay coil driving circuit, the size of a single plate is reduced, and the power density is improved.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.