Relay drive circuit and power device applying the same

Abstract

The present application relates to a kind of relay driving circuit and the electric power equipment of application thereof.The relay driving circuit is connected with the relay to be driven, including stabilivolt, diode, PWM drive signal output module and switch tube, stabilivolt and diode are connected in series and then reverse parallel in the coil of relay both ends, the input end of the coil of relay is connected power supply, the output end of the coil of relay is grounded via switch tube, PWM drive signal output module is connected with the control end of switch tube;Relay driving circuit further includes when relay attracts and maintains attraction short-circuit stabilivolt, open circuit when relay is disconnected and makes stabilivolt work stabilivolt control module, stabilivolt control module is connected at stabilivolt both ends.The electric power equipment includes relay and the aforementioned relay driving circuit.The electric power equipment is inverter, PCS or UPS.The present application can greatly improve the turn-off speed of relay, and the additional loss caused by fast turn-off circuit is very low, and efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of control driving circuit and power electronic equipment, and particularly relates to a driving circuit for a relay and a power device applying the same. BACKGROUND

[0002] The working principle of a relay is that a rated current is needed to magnetize a coil to provide the energy for attraction when the relay is attracted, and only a small current is needed to maintain the relay in the attracted state after the attraction is completed. The relay is widely used in power devices, for example, in a photovoltaic inverter, the on / off grid switching of the inverter output is generally controlled by a relay, and the speed of the relay opening and closing affects the switching time.

[0003] A commonly used relay driving circuit is shown in FIG. 1, which needs double power supply in the driving circuit, and a large-capacity electrolytic capacitor C1 needs to be selected, increasing the design cost. Another two existing relay driving circuits are shown in FIGS. 2 and 3, respectively, and a Zener diode or an RC is added in the relay freewheeling circuit to increase the relay turn-off speed, but the loss of the circuit is greatly increased, affecting the efficiency of the system. Figure 1 Figure 2 Figure 3

[0004] Therefore, the existing relay driving circuit has the following defects:

[0005] 1. The normal turn-off speed of the relay is slow, which cannot meet the application scenarios that require fast turn-off.

[0006] 2. In the conventional acceleration turn-off circuit, passive devices such as RC or Zener diode are added, which results in a large loss of the circuit when the relay is normally maintained in the attracted state. SUMMARY

[0007] The purpose of the present application is to provide a relay driving circuit that can improve the turn-off speed of the relay, reduce additional loss, and improve efficiency.

[0008] To achieve the above purpose, the technical solution adopted by the present application is as follows:

[0009] A relay driving circuit is connected to a relay to be driven, and the relay driving circuit comprises a Zener diode, a diode, a PWM driving signal output module, and a switch tube. The Zener diode and the diode are connected in series and are connected in reverse parallel across the coil of the relay. The input end of the coil of the relay is connected to a power supply, the output end of the coil of the relay is connected to the ground through the switch tube, and the PWM driving signal output module is connected to the control end of the switch tube.

[0010] ​​​The relay driving circuit further comprises a Zener diode control module for short-circuiting the Zener diode when the relay is attracted and maintained in attraction and opening the Zener diode to make the Zener diode work when the relay is disconnected, and the Zener diode control module is connected at both ends of the Zener diode.

[0011] The switch tube is a triode, the base of the triode is connected with the PWM driving signal output module, the collector of the triode is connected with the coil of the relay, and the emitter of the triode is grounded.

[0012] The PWM driving signal output module is connected with the base of the triode through a resistor.

[0013] The relay driving circuit further comprises a capacitor, and the capacitor is connected between the power supply and the ground.

[0014] The application further provides a power device using the above relay driving circuit, and the scheme is as follows:

[0015] A power device comprises a relay and the above relay driving circuit. The power device is an inverter, a PCS or a UPS.

[0016] By using the above technical scheme, the application has the following advantages compared with the prior art: the application can greatly improve the turn-off speed of the relay, and the additional loss caused by the fast turn-off circuit is very low, and the efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Fig. 1 is a schematic diagram of a prior art double power supply relay driving circuit. Figure 1 Fig. 2 is a schematic diagram of a prior art relay driving circuit with a Zener diode fast turn-off circuit.

[0018] Fig. 3 is a schematic diagram of a prior art relay driving circuit with an RC fast turn-off circuit. Figure 2 Fig. 4 is a schematic diagram of a relay driving circuit of the application.

[0019] Figure 3 Fig. 5 is a schematic diagram of a power device of the application.

[0020] Fig. 6 is a schematic diagram of a power device of the application. Figure 4 DETAILED DESCRIPTION

[0021] The application will be further described below in combination with the embodiments shown in the drawings.

[0022] Embodiment 1: as shown in Fig. 4, a relay driving circuit comprises a Zener diode ZD1, a diode D1, a PWM driving signal output module, a switch tube, a capacitor C2, a resistor R6 and a Zener diode control module. Figure 4

[0023] ​​​The relay driving circuit is connected with the coil of the relay RY1 to be driven. Specifically, the input end of the coil of the relay RY1 is connected with the power supply Vcc, and the output end of the coil of the relay RY1 is connected with the ground through the switching tube. The switching tube is a triode Q3, and the collector of the triode Q3 is connected with the output end of the coil of the relay RY1, and the emitter of the triode Q3 is grounded. The capacitor C2 is connected between the power supply Vcc and the ground. The PWM driving signal output module is connected with the control end of the switching tube, i.e. the base of the triode Q3, through the resistor R6. The PWM driving signal output module is used to output the PWM signal with adjustable duty cycle.

[0024] The Zener ZD1 and the diode D1 are connected in series and then reversely connected in parallel across the coil of the relay RY1, i.e. the positive electrode of the diode D1 is connected with the output end of the coil of the relay RY1, the negative electrode of the diode D1 is connected with the negative electrode of the Zener ZD1, and the positive electrode of the Zener ZD1 is connected with the output end of the coil of the relay RY1. The Zener control module is connected across the Zener ZD1, and the Zener control module is used to short-circuit the Zener ZD1 when the relay RY1 is attracted and maintained, and open the Zener ZD1 when the relay RY1 is disconnected, so that the Zener ZD1 works. For example, the Zener control module can include a switching device connected across the Zener ZD1 and switched according to the action state of the Zener ZD1, so as to realize short-circuiting or opening. The Zener control module can be connected with the PWM driving signal output module, so as to be controlled by the PWM driving signal output by the PWM driving signal output module.

[0025] The working principle of the above relay driving circuit is as follows:

[0026] The power supply Vcc of the relay RY1 can be higher than the voltage of the coil winding of the relay RY1 according to the requirement of the attraction speed. During the attraction and maintenance of the relay RY1, the Zener control module is short-circuited across the Zener ZD1, so that the Zener ZD1 loses the effect; and during the disconnection of the relay RY1, the Zener control module is opened across the Zener ZD1, so that the Zener ZD1 works at this time, and adds a reverse high voltage to the two ends of the relay RY1, so as to accelerate the discharge of the winding current of the relay RY1.

[0027] When the relay RY1 is attracted, the Zener control module works, the Zener ZD1 is in a short-circuit state, the triode Q3 is controlled by adjusting the duty cycle of the PWM driving signal, the attraction speed of the relay RY1 is adjusted, and the maximum duty cycle of the PWM driving signal can be 100%.

[0028] When the relay RY1 is maintained, the Zener control module works, at this time, the Zener ZD1 is short-circuited, by adjusting the duty cycle of the PWM drive signal to control the transistor Q3, adjust the current of the relay RY1, generally is the rated current of the relay RY1 winding about 50% (according to the actual relay specification book), reduce the maintenance power consumption of the relay RY1; when the transistor Q3 is open, the power supply Vcc charges the relay RY1 winding; when the transistor Q3 is off, the relay RY1 winding through the diode D1 and Zener control module freewheeling.

[0029] When the relay RY1 is off, the PWM drive signal output module outputs low level, the Zener control module loses its function, the transistor Q3 is off, the relay RY1 winding through the diode D1 and Zener ZD1 discharge, accelerate the relay RY1 off speed.

[0030] The above-mentioned relay drive circuit can be applied to various power equipment including relays, such as inverters, PCS or UPS, etc. Taking a photovoltaic inverter as an example, the input end of the photovoltaic inverter is connected to a photovoltaic power generation system, and the output end is connected to a power grid. The photovoltaic inverter includes an inverter circuit, and the output end of the inverter circuit is connected to the power grid through a relay, so that the switching between grid-connected and off-grid of the inverter output and the power grid can be realized by controlling the relay. Therefore, the above-mentioned inverter drive circuit connected to the relay can be arranged in the photovoltaic inverter, so that the rapid switching of the grid-connected state of the inverter can be realized.

[0031] The above-mentioned embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A relay driving circuit, connected to a relay to be driven, characterized in that: The relay driving circuit includes a Zener diode, a diode, a PWM drive signal output module, and a switching transistor. The Zener diode and the diode are connected in series and then in reverse parallel across the coil of the relay. The input terminal of the relay coil is connected to a power supply, and the output terminal of the relay coil is grounded through the switching transistor. The PWM drive signal output module is connected to the control terminal of the switching transistor. The relay drive circuit further includes a Zener diode control module that short-circuits the Zener diode when the relay is engaged and maintained engaged, and opens the Zener diode when the relay is disengaged, thereby enabling the Zener diode to operate. The Zener diode control module is connected to both ends of the Zener diode. The switching transistor is a triode, the PWM drive signal output module is connected to the base of the triode, the collector of the triode is connected to the coil of the relay, and the emitter of the triode is grounded. When the relay is engaged and maintained, and when the transistor is disengaged, the relay coil continues to flow through the diode and the Zener diode control module.

2. The relay drive circuit according to claim 1, characterized in that: The PWM drive signal output module is connected to the base of the transistor via a resistor.

3. The relay drive circuit according to claim 1, characterized in that: The relay drive circuit also includes a capacitor connected between the power supply and ground.

4. An electrical device, comprising a relay, characterized in that: The power equipment further includes a relay drive circuit as described in any one of claims 1 to 3.

5. The power equipment according to claim 4, characterized in that: The power equipment is an inverter, PCS, or UPS.

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