CN212811275U

CN212811275U - Interlocking protection circuit convenient to set up voltage threshold

Info

Publication number: CN212811275U
Application number: CN202021587511.5U
Authority: CN
Inventors: 朱永亮; 王淑惠
Original assignee: CETC 14 Research Institute
Current assignee: CETC 14 Research Institute
Priority date: 2020-08-03
Filing date: 2020-08-03
Publication date: 2021-03-26
Anticipated expiration: 2030-08-03

Abstract

The utility model relates to an interlock protection circuit convenient to set up voltage threshold, including triode Q4, resistance R1, resistance R2, resistance R3 and resistance R4, resistance R1 and resistance R2's one end is connected to triode Q4's base respectively, voltage Vout1 is connected to the resistance R1 other end, voltage Vout2 is connected to the resistance R2 other end, resistance R3 sets up between triode Q4's collecting electrode and projecting pole, triode Q4's collecting electrode is connected to resistance R4 one end, voltage signal Vout1 is connected to the other end; the collector of the transistor Q4 outputs a control signal SHDN that controls the on and off of the output voltage Vout 3. The application can realize the closing function of the protection circuit under different voltage abnormity, the protection voltage threshold can be set, the characteristics of few devices, simple circuit and convenient realization can be realized, and the requirement of safety protection of a switching power supply or a power supply system can be met.

Description

Interlocking protection circuit convenient to set up voltage threshold

Technical Field

The utility model relates to a switching power supply protection circuit field especially relates to an interlocking protection circuit convenient to set up voltage threshold.

Background

With the continuous development of radar technology and communication technology, the application of a switching power supply is more and more extensive, direct-current voltages with different specifications are used in a radar power supply and distribution system, the voltages with different specifications have the requirement on a power-up sequence, and the high-voltage output needs to be quickly closed under the condition that the low-voltage output is abnormal, so that the purpose of safe operation of the system is achieved.

The safety design needs to realize the interlocking protection of low-voltage output to high-voltage output, namely, the high-voltage output is timely and quickly turned off when the low-voltage output is reduced to a certain degree. The document [1] gives a high-voltage interlocking design of automotive electronics, but is mainly realized by using a mechanical switch, has large volume and complex design, and is not beneficial to the miniaturization design of a power supply system. The document [2] provides an interlock protection circuit with optical coupling isolation, which can realize an interlock closing function for high-voltage output only when the low-voltage output is very low or close to zero volt, and cannot protect when the low-voltage output is reduced to a certain degree (or a set threshold). In order to realize the interlocking protection of low-voltage output to high-voltage output and conveniently set the voltage threshold for starting protection, a circuit needs to be designed by adopting devices as few as possible, so that the aim of safety protection is fulfilled, the miniaturization of the circuit is realized, and the reliability of system operation is improved.

Wherein, the documents [1] and [2] are respectively:

[1] li gao lin, huang dancao et al electric vehicle high voltage interlock research [ J ] vehicle electrical, 2013, 5: 1-3.

[2] Two-way hot plug circuit design [ J ] based on LT 1641. electronic component application, 2008, 10 (4): 4-7.

SUMMERY OF THE UTILITY MODEL

For solving the prior art problem, the utility model provides an interlocking protection circuit convenient to set up voltage threshold.

The utility model discloses specific content as follows: an interlock protection circuit convenient for setting a voltage threshold comprises a triode Q4, a resistor R1, a resistor R2, a resistor R3 and a resistor R4, wherein one ends of a resistor R1 and a resistor R2 are respectively connected to a base electrode of a triode Q4, the other end of the resistor R1 is connected with a voltage Vout1, the other end of a resistor R2 is connected with a voltage Vout2, a resistor R3 is arranged between a collector electrode and an emitter electrode of a triode Q4, one end of a resistor R4 is connected with a collector electrode of a triode Q4, and the other end of the resistor R4 is connected with a voltage signal; the collector of the transistor Q4 outputs a control signal SHDN that controls the on and off of the output voltage Vout 3.

Further, the voltage Vout1 is generated by a voltage signal Vin1 via a first signal generating circuit, the first signal generating circuit includes a switching tube Q1, an inductor L1, a diode D1 and a capacitor C1, the switching tube Q1 is connected in series with the inductor L1, one end of the diode D1 and one end of the capacitor C1 are respectively disposed at two ends of the inductor L1, the other end of the diode D1 and the other end of the capacitor C1 are respectively grounded, a gate of the switching tube Q1 is connected to a first control circuit, and the first control circuit controls the switching tube Q1 to be turned on and off.

Further, the voltage Vout2 is generated by a voltage signal Vin2 via a second signal generating circuit, the second signal generating circuit includes a switching tube Q2, a diode D2, an inductor L2 and a capacitor C2, the switching tube Q2 is connected in series with the diode D2, one end of the inductor L2 and one end of the capacitor C2 are connected to two ends of the diode D2, the other ends of the inductor L2 and the capacitor C2 are respectively grounded, a gate of the switching tube Q2 is connected to a second control circuit, and the second control circuit controls the switching tube Q2 to be turned on and off.

Further, the output voltage Vout3 is generated by the input voltage Vin3 through a third signal generating circuit, and the control signal SHDN controls the output signal Vout3 through a third control circuit controlling the third signal generating circuit; the third signal generating circuit comprises a switching tube Q3, an inductor L3, a diode D3 and a capacitor C3, the switching tube Q3 is connected in series with the inductor L3, one end of the diode D3 and one end of the capacitor C3 are respectively connected to two ends of the inductor L3, the other end of the diode D3 and the other end of the capacitor C3 are respectively grounded, the input signal Vin is connected to a drain electrode of the switching tube Q3, a gate electrode of the switching tube Q3 is connected with a third control circuit, and the third control circuit controls the on and off of the switching tube Q3.

Further, the control signal SHDN is isolated by the optocoupler N1 to generate a control signal SHDN1, and the control signal SHDN1 controls the output voltage Vout 3.

Further, the control signal SHDN is connected to an input end of the comparator N2, another input end of the comparator N2 is connected to the reference voltage Vref, an output signal of the comparator is connected to an input end of the optocoupler N1, the optocoupler N1 isolates the output control signal SHDN1, and the control signal SHDN1 controls the turn-off of the output voltage Vout 3.

The utility model has the advantages that: the power supply circuit can realize the closing function of a circuit needing protection under different voltage abnormity, can set the protection voltage threshold, has the characteristics of few devices, simple circuit and convenient realization, and can meet the requirement of safety protection of a switching power supply or a power supply system.

Drawings

The following further explains the embodiments of the present invention with reference to the drawings.

Fig. 1 is a schematic view of embodiment 1 of the present invention;

fig. 2 is a schematic view of embodiment 2 of the present invention;

fig. 3 is a schematic diagram of embodiment 3 of the present invention.

Detailed Description

Example 1

As shown in fig. 1, the present embodiment discloses an interlock protection circuit for conveniently setting a voltage threshold, which is suitable for the situation that a protection voltage threshold can be set without isolation requirements.

In the interlock protection circuit in this embodiment, the interlock protection circuit includes a transistor Q4, a resistor R1, a resistor R2, a resistor R3, and a resistor R4, wherein the resistor R1 and the resistor R2 are respectively connected to a base of the transistor Q4, the resistor R3 is connected between a collector and an emitter of the transistor Q4, one end of the resistor R4 is connected to the collector of the transistor Q4, and the other end of the resistor R1 is connected to the resistor R.

The interlock protection circuit further comprises three output voltages Vout1, Vout2 and Vout3, wherein Vout1 is a positive output voltage, Vout2 is a negative output voltage, Vout3 can be a positive output or a negative output voltage, Vout1 is connected between the electron R1 and the resistor R4, and Vout2 is connected to the resistor R2. The transistor Q4 is an NPN transistor, and the output signal SHDN at the collector thereof is used as a control signal to control the on and off of Vout 3.

The voltage Vout1 is generated by a voltage signal Vin1 through a first signal generating circuit, the first signal generating circuit comprises a switching tube Q1, an inductor L1, a diode D1 and a capacitor C1, the switching tube Q1 is connected in series with the inductor L1, one end of the diode D1 and one end of the capacitor C1 are respectively arranged at two ends of the inductor L1, and the other ends of the diode D1 and the capacitor C1 are respectively grounded; the voltage Vout2 is generated by a voltage signal Vin2 via a second signal generating circuit, the second signal generating circuit includes a switching tube Q2, a diode D2, an inductor L2 and a capacitor C2, the switching tube Q2 is connected in series with the diode D2, one end of the inductor L2 and one end of the capacitor C2 are connected to two ends of the diode D2, and the other ends are respectively grounded.

In this embodiment, the input voltage Vin3 of the voltage Vout3 is generated by a third signal generating circuit. The third signal generating circuit comprises a switching tube Q3, an inductor L3, a diode D3 and a capacitor C3, wherein the switching tube Q3 is connected with the inductor L3 in series, one end of the diode D3 and one end of the capacitor C3 are respectively connected to two ends of the inductor L3, and the other ends of the diode D3 and the capacitor C3 are respectively grounded.

In this embodiment, the input voltages Vin1, Vin2, and Vin3 may be supplied by the same power source or different power sources. The gates of the switching tubes in the first signal generating circuit, the second signal generating circuit and the third signal generating circuit are respectively connected with the first control circuit 1, the second control circuit 2 and the third control circuit 3, the first control circuit 1, the second control circuit 2 and the third control circuit 3 are respectively control chips or circuits of three circuits, and the corresponding switching tubes are controlled to be switched on and off, and can be selected according to needs in practical use.

In this embodiment, the transistor Q4 is turned on or off between the collector and the emitter to serve as a control signal (i.e., SHDN) of low and high levels, and when the SHDN is low, the output voltage Vout3 is turned off; the voltage Vout1 is divided by the resistor R1 and the resistor R2 to set the magnitude of the control signal SHDN, so that the interlock protection can be realized while the voltage protection threshold is set.

The interlocking protection circuit adopts 1 NPN type triode and 4 resistors to design a circuit, and utilizes the conduction or the disconnection between the collector and the emitter of the triode as a low-level and high-level control signal SHDN to realize the closing protection of the output voltages of Vout1 and Vout2 to the output voltage of Vout 3. On the setting of the protection voltage threshold value, the resistors R3 and R4 are used for dividing the output voltage of Vout1, and control signals SHDN with different voltage values can be sent out, so that the protection of the output voltage of Vout1 against the output voltage of Vout3 is realized. The resistors R1 and R2 are used for dividing the voltage of Vout1+ Vout2, and a corresponding control signal SHDN is sent out by combining the voltage difference between the base electrode and the emitter electrode of the triode Q4, so that the turn-off protection of the output voltage of Vout2 to the output voltage of Vout3 is realized.

When any one of the two output voltages Vout1 and Vout2 has an abnormal fault and the output voltage is lower than the set threshold voltage, the interlock protection circuit can respond in time and send out a corresponding signal to close the voltage output of the third path Vout3, thereby improving the safety of the system. Since the third path of the output voltage of the Vout3 has no isolation requirement with the two paths of the output of the Vout1 and the Vout2, the interlock protection circuit can directly turn off the output of the Vout 3.

Referring to fig. 1, the switching power supply circuit with Vout1 outputting +3.3V, Vout2 outputting-3.3V, and Vout3 outputting +9V is selected as an example in this embodiment, and the operation principle is as follows.

When the voltages of Vout1 and Vout2 are both normal, the base and emitter voltages Ube of the transistor Q4 can be determined by the resistance values of the resistors R1 and R2, the base voltage to ground voltage of the transistor Q4 can be set to be less than 0.7V, so that the ce electrode of the transistor is not conducted, and the level of the output end of the SHDN is determined by R3 and R4.

When Vout1 is no output when +3.3V, or the voltage is low to a certain amplitude, the SHDN end will send a low level signal to the control circuit 3 of +9V voltage, and close the output of +9V voltage, thus realizing the interlock protection of +3.3V to +9V voltage. The setting of the magnitude of the +3.3V voltage droop level may be determined by selecting the resistance values of R3 and R4, as follows:

Uth1＝Ushdn*(1+R4/R3)

where Uth1 is the threshold voltage to be set for +3.3V to start interlock protection and Ushdn is the minimum operating voltage required by the +9V control circuit.

In the circuit shown in fig. 1, when Vout2 is-3.3V and there is no output or the voltage is low to a certain amplitude, Ube of the transistor Q4 is >0.7V, the ce electrode of the transistor Q4 is turned on, the SHDN output terminal is pulled to a low level, the SHDN output terminal sends a low level signal to the control circuit of +9V voltage, and the output of +9V voltage is turned off, so that the interlock protection of-3.3V voltage to +9V voltage is realized. The setting of the magnitude of the-3.3V voltage droop level may be determined by the resistances of resistors R1 and R2, as follows:

Uth2＝(3.3-Ube)*R2/R1-Ube

wherein Uth2 is the threshold voltage of-3.3V to be set for starting interlock protection, and Ube is the voltage between be electrodes of the triode.

Different resistance values of the resistors are selected, and the interlocking protection effect of +3.3V and-3.3V on +9V can be verified. The resistance values and the corresponding interlocking effects are shown in table 1:

TABLE 1

The + 3.3V-3.3V output voltage can be set to be closed to the +9V output voltage by adjusting the resistance values of the resistors R1, R2, R3 and R4, and the interlocking protection function under different voltages is realized.

The interlocking protection circuit of the embodiment can close the circuit output to be protected when the positive output voltage is reduced to a certain amplitude, and can also close the circuit output to be protected when the negative output voltage (voltage absolute value) is reduced to a certain amplitude, thereby realizing the interlocking protection function of low-voltage output on high-voltage output and ensuring the operation safety of a power supply system; the voltage threshold needing to start protection can be set by utilizing the voltage division of the resistor and the voltage characteristic of the electrode of the triode be; when the protection voltage threshold is set, the protection circuit can be started in the process of output voltage reduction, and the protection circuit does not need to be started again when the voltage is reduced to zero volts, so that the interlocking protection response is more timely and faster; meanwhile, on the basis of the designed output voltage circuit, a few devices are added to realize the protection of the circuit, the device cost is low, the components used by the circuit are general and conventional devices, and the devices are easy to purchase and select, so that the circuit has high practical significance.

Example 2

As shown in fig. 2, this embodiment discloses an interlock protection circuit (a signal generation circuit of the voltage Vout3 is not shown, and the circuit is the same as that in embodiment 1) with isolation requirement and capable of setting voltage threshold.

The difference between this embodiment and embodiment 1 is mainly that a comparator N2 and an optocoupler N1 are connected after the control signal SHDN, the comparator N2 is further connected with a pull-up resistor R5, the pull-up resistor R5 is connected with a voltage Vp, a collector of a phototransistor of the optocoupler N1 is connected with a resistor R6, and a resistor R6 is connected with a voltage Vs. After the control signal passes through the comparator N2 and the optocoupler N1, the control signal SHDN1 for isolation is generated and controls the third signal generating circuit, and other technical features are the same as those in embodiment 1, and therefore are not described herein.

In this embodiment, the control signal SHDN generated after the voltage Vout1 and the voltage Vout2 pass through the interlock protection circuit passes through the comparator N2, and is compared with the reference voltage Vref to output a comparison result. The reference voltage Vref can be set as the threshold value of the control signal SHDN, the output of the comparator N2 controls the on and off of the light emitting diode of the optocoupler N1, and the secondary of the optocoupler N1 sends a closing signal SHDN1 to close the Vin3, so that the voltage output of Vout3 is closed, and the interlock protection is realized.

Example 3

As shown in fig. 3, this embodiment discloses an interlock protection circuit (the signal generating circuit of the voltage Vout3 is not shown in the figure, and the circuit is the same as that in embodiment 1) having an isolation requirement and capable of setting a protection threshold of a negative output voltage.

The difference between this embodiment and embodiment 2 is that no comparator N2 is provided, a control signal enters the optocoupler N1, and Vin3 is turned off when the control signal SHDN1 is generated at the secondary of the optocoupler N1 and SHDN1 is at a low level, so that the voltage output of Vout3 is turned off. The remaining technical features are the same as those of embodiment 2, and are not described again here.

It can be seen from the above embodiments that the interlock protection circuit of the present application can implement a design under the conditions of no threshold requirement or isolation requirement, and has a wide application range.

In the previous description, numerous specific details were set forth in order to provide a thorough understanding of the invention. The foregoing description is only illustrative of the preferred embodiments of the invention, which can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. All the contents that do not depart from the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical substance of the present invention all still belong to the protection scope of the technical solution of the present invention.

Claims

1. An interlock protection circuit for facilitating setting a voltage threshold, comprising: the voltage regulator comprises a triode Q4, a resistor R1, a resistor R2, a resistor R3 and a resistor R4, wherein one ends of the resistor R1 and the resistor R2 are respectively connected to the base of the triode Q4, the other end of the resistor R1 is connected with a voltage Vout1, the other end of the resistor R2 is connected with a voltage Vout2, a resistor R3 is arranged between the collector and the emitter of the triode Q4, one end of a resistor R4 is connected with the collector of the triode Q4, and the other end of the resistor R4 is connected with a voltage signal; the collector of the transistor Q4 outputs a control signal SHDN that controls the on and off of the output voltage Vout 3.

2. The interlock protection circuit for facilitating setting a voltage threshold of claim 1, wherein: the voltage Vout1 is generated by a voltage signal Vin1 through a first signal generating circuit, the first signal generating circuit comprises a switching tube Q1, an inductor L1, a diode D1 and a capacitor C1, the switching tube Q1 is connected in series with the inductor L1, one end of the diode D1 and one end of the capacitor C1 are respectively arranged at two ends of the inductor L1, the other end of the diode D1 and the other end of the capacitor C1 are respectively grounded, a grid electrode of the switching tube Q1 is connected with a first control circuit, and the first control circuit controls the on and off of the switching tube Q1.

3. The interlock protection circuit for facilitating setting a voltage threshold of claim 1, wherein: the voltage Vout2 is generated by a voltage signal Vin2 via a second signal generating circuit, the second signal generating circuit includes a switching tube Q2, a diode D2, an inductor L2 and a capacitor C2, the switching tube Q2 is connected in series with the diode D2, one end of the inductor L2 and one end of the capacitor C2 are connected to two ends of the diode D2, the other ends of the inductor L2 and the capacitor C2 are respectively grounded, a gate of the switching tube Q2 is connected to a second control circuit, and the second control circuit controls the switching-on and switching-off of the switching tube Q2.

4. The interlock protection circuit for facilitating setting a voltage threshold of claim 1, wherein: the output voltage Vout3 is generated by the input voltage Vin3 through a third signal generating circuit, and the control signal SHDN controls the output signal Vout3 through a third control circuit controlling the third signal generating circuit; the third signal generating circuit comprises a switching tube Q3, an inductor L3, a diode D3 and a capacitor C3, the switching tube Q3 is connected in series with the inductor L3, one end of the diode D3 and one end of the capacitor C3 are respectively connected to two ends of the inductor L3, the other end of the diode D3 and the other end of the capacitor C3 are respectively grounded, the input signal Vin is connected to a drain electrode of the switching tube Q3, a gate electrode of the switching tube Q3 is connected with a third control circuit, and the third control circuit controls the on and off of the switching tube Q3.

5. The interlock protection circuit for facilitating setting a voltage threshold of claim 1, wherein: the control signal SHDN is isolated by the optocoupler N1 to generate a control signal SHDN1, and the control signal SHDN1 controls the output voltage Vout 3.

6. The interlock protection circuit for facilitating setting a voltage threshold of claim 1, wherein: the control signal SHDN is connected to the input end of the comparator N2, the other input end of the comparator N2 is connected with the reference voltage Vref, the output signal of the comparator is connected to the input end of the optocoupler N1, the optocoupler N1 isolates the output control signal SHDN1, and the control signal SHDN1 controls the turn-off of the output voltage Vout 3.