CN207283139U - A kind of delay overcurrent turn-off function circuit for elevator switch power supply - Google Patents

Abstract

The utility model discloses a time-delayed overcurrent shut-off circuit for an elevator switching power supply, comprising a power supply circuit, a reference voltage circuit, an open-loop current amplification circuit, a charging current delay circuit, a voltage comparison circuit, and an output current sampling circuit. The output current sampling circuit includes a sampling resistor J1 and a voltage dividing resistor. The right end of the sampling resistor J1 is connected to the ground and the negative output terminal VO‑ of the switching power supply, and the left end is connected to the positive output terminal VO+ of the switching power supply through the voltage dividing resistor and amplified with the switching current One end of the circuit is connected; the reference voltage circuit includes a power supply terminal, an output terminal, and a ground terminal, and the power supply terminal is connected to the output terminal of the power supply circuit; the output terminal of the open-loop current amplification circuit is connected to the output terminal of the voltage comparison circuit through the charging current delay circuit , the output terminal of the voltage comparison circuit is connected with the chip pin for controlling the pulse width of the integrated circuit. The utility model has the advantages that the circuit has the characteristics of simple circuit, reliable protection and high precision.

Description

A time-delayed over-current shutdown circuit for elevator switching power supply

technical field

The utility model relates to the technical field of automatic protection circuits, in particular to a time-delayed overcurrent shut-off circuit for an elevator switching power supply.

Background technique

The switching power supply for elevators is required to have a short-term overload capability, but simply increasing the overcurrent capability of the switching power supply will cause danger when the elevator control system has an overload fault, so the demander proposes to use it in the existing HF150W-S switching power supply circuit Install power-up delay protection circuit.

Utility model content

In order to overcome the shortcomings of the above-mentioned prior art, the purpose of this utility model is to solve the problem of how to protect the switching power supply used in elevators in the prior art. Therefore, the utility model provides a time-delayed overcurrent switch for elevator switching power break the circuit.

In order to achieve the above object, the utility model adopts the following technical solutions:

A time-delayed overcurrent shutdown circuit for an elevator switching power supply, comprising a power supply circuit, a reference voltage circuit, an open-loop current amplification circuit, a charging current delay circuit, a voltage comparison circuit, and an output current sampling circuit, the output current sampling circuit The circuit includes a sampling resistor J1 and a voltage dividing resistor. The right end of the sampling resistor J1 is connected to the ground and the negative output terminal VO- of the switching power supply, and the left end is connected to the positive output terminal VO+ of the switching power supply through the voltage dividing resistor and to one end of the switching current amplification circuit. connect;

The reference voltage circuit includes a power supply terminal, an output terminal, and a ground terminal, and the power supply terminal is connected to the output terminal of the power supply circuit;

Described open-loop current amplifying circuit comprises operational amplifier IC4A, resistance R39, resistance R33, resistance R34, resistance R35, resistance R38, potentiometer VR2, and one end of described resistance R34 and one end of resistance R35 are connected with the output end of reference voltage circuit respectively Connection, the other end of the resistor R34 is connected to the negative input terminal of the operational amplifier IC4A, the other end of the resistor R35 is connected to the negative input terminal of the operational amplifier IC4A, the left end of the sampling resistor J1 passes through the resistor R39, the potentiometer VR2 and the negative input terminal of the operational amplifier IC4A. The input terminal is connected, and the positive input terminal of the operational amplifier IC4A is connected to the ground through the resistor R38; the output terminal of the operational amplifier IC4A is connected to the output terminal of the voltage comparison circuit through the charging current delay circuit, and the output terminal of the voltage comparison circuit is integrated with the control The pulse width of the circuit is connected to the chip pin.

Optimally, the charging current delay circuit includes a resistor R40 and a capacitor C26, the output terminal of the operational amplifier IC4A is connected to the right end of the resistor R40, and the left end of the resistor R40 is connected to the ground through the electrolytic capacitor C26.

Optimal, described voltage comparator circuit comprises operational amplifier IC4B, diode D12, diode D16, resistance R49, the left end of described resistance R40 is also connected with the positive input terminal of operational amplifier IC4B, the output terminal of operational amplifier IC4B passes through diode D16 and resistance R49 is connected to the anode of the operational amplifier IC4B, and is also connected to the input terminal of the diode D12, and the output terminal of the diode D12 is used as the output terminal of the voltage comparison circuit.

Optimally, the operational amplifier IC4A and the operational amplifier IC4B form the operational amplifier IC4, and the model of the operational amplifier IC4 is LM358.

Optimally, the power circuit includes a power chip IC2 and an electrolytic capacitor C14, the input end of the power chip is connected to an external power supply, the output end is connected to the power end of the reference voltage circuit and the positive pole of the electrolytic capacitor C14, and the negative pole of the electrolytic capacitor C14 is connected to the ground connect.

Optimally, the model of the power chip IC2 is IM7812.

Optimally, the reference voltage circuit includes a resistor R33, a three-terminal adjustable voltage reference chip IC3, and a capacitor C27. One end of the resistor R33 is used as a power supply terminal, and the other end is connected to the anode of the three-terminal adjustable voltage reference chip IC3 as a The output end of the reference voltage circuit, the reference end is connected to the anode, the cathode is connected to the ground, and the capacitor C27 is connected in parallel between the anode and the cathode of the three-terminal adjustable voltage reference chip IC3.

Optimally, the model of the three-terminal adjustable voltage reference chip IC3 is TL431.

Optimally, the delay time of the charging current delay circuit is 3-9 seconds.

Optimally, the voltage dividing resistor includes a resistor R47 and a resistor R48, and the output current sampling circuit further includes a resistor R46 and an LED lamp, and the resistor R46 and the LED lamp are connected in series between the positive output terminal VO+ and the negative output terminal of the switching power supply There are multiple capacitors connected in parallel between the positive output terminal and the negative output terminal, the resistor R47 is connected in parallel with the resistor R48, and multiple capacitors are connected in parallel between the two ends of the resistor R47.

The circuit of the utility model is specially used in the switching power supply of KA7500C as the power controller, and has the characteristics of simple circuit, reliable protection and high precision.

Description of drawings

Fig. 1 is a circuit diagram of a time-delayed overcurrent shut-off circuit for an elevator switching power supply according to the present invention.

Detailed ways

As shown in Figure 1, a time-delayed overcurrent shutdown circuit for elevator switching power supply, including a power supply circuit, a reference voltage circuit, an open-loop current amplification circuit, a charging current delay circuit, a voltage comparison circuit, and an output current sampling circuit , the output current sampling circuit includes a sampling resistor J1 and a voltage dividing resistor, the right end of the sampling resistor J1 is connected to the ground and the negative output terminal VO- of the switching power supply, and the left end is connected to the positive output terminal VO+ of the switching power supply through the voltage dividing resistor and connected to One end of the switching current amplification circuit is connected;

The reference voltage circuit includes a power supply terminal, an output terminal, and a ground terminal, and the power supply terminal is connected to the output terminal of the power supply circuit;

Described open-loop current amplifying circuit comprises operational amplifier IC4A, resistance R39, resistance R33, resistance R34, resistance R35, resistance R38, potentiometer VR2, and one end of described resistance R34 and one end of resistance R35 are connected with the output end of reference voltage circuit respectively Connection, the other end of the resistor R34 is connected to the negative input terminal of the operational amplifier IC4A, the other end of the resistor R35 is connected to the negative input terminal of the operational amplifier IC4A, the left end of the sampling resistor J1 passes through the resistor R39, the potentiometer VR2 and the negative input terminal of the operational amplifier IC4A. The input terminal is connected, and the positive input terminal of the operational amplifier IC4A is connected to the ground through the resistor R38; the output terminal of the operational amplifier IC4A is connected to the output terminal of the voltage comparison circuit through the charging current delay circuit, and the output terminal of the voltage comparison circuit is integrated with the control The pulse width of the circuit is connected to the chip pin. The resistance values of the resistor R34 and the resistor R35 are both 22KΩ, the resistance value of the resistor R39 is 430Ω, the maximum resistance value of the potentiometer VR2 is 500Ω, and the resistance value of the resistor R38 is 15Ω.

The charging current delay circuit includes a resistor R40 and a capacitor C26. The output terminal of the operational amplifier IC4A is connected to the right end of the resistor R40, and the left end of the resistor R40 is connected to the ground through the electrolytic capacitor C26. The resistance value of the resistor R40 is 220KΩ, and the capacitance value of the capacitor C26 is 100UF. The delay time of the charging current delay circuit is 3-9 seconds.

Described voltage comparator circuit comprises operational amplifier IC4B, diode D12, diode D16, resistance R49, and the left end of described resistance R40 is also connected with the positive input terminal of operational amplifier IC4B, and the output end of operational amplifier IC4B passes through diode D16 and resistance R49 and operation The anode of the amplifier IC4B is connected to the input terminal of the diode D12, and the output terminal of the diode D12 is used as the output terminal of the voltage comparison circuit. Wherein, the resistance value of the resistor R49 is 6.3KΩ, and the models of the diode D12 and the diode D16 are 1N4148.

The operational amplifier IC4A and the operational amplifier IC4B form the operational amplifier IC4, and the model of the operational amplifier IC4 is LM358.

The power circuit includes a power chip IC2 and an electrolytic capacitor C14. The input end of the power chip is connected to an external power supply, the output end is connected to the power end of the reference voltage circuit and the positive pole of the electrolytic capacitor C14, and the negative pole of the electrolytic capacitor C14 is connected to the ground. The capacitance value of the electrolytic capacitor C14 is 100UF. The model of the power supply chip IC2 is IM7812, and the power supply circuit outputs 12V voltage.

The reference voltage circuit includes a resistor R33, a three-terminal adjustable voltage reference chip IC3, and a capacitor C27. One end of the resistor R33 is used as a power supply terminal, and the other end is connected to the anode of the three-terminal adjustable voltage reference chip IC3 as a reference voltage circuit. The output terminal of the reference terminal is connected to the anode, the cathode is connected to the ground, and the capacitor C27 is connected in parallel between the anode and the cathode of the three-terminal adjustable voltage reference chip IC3. The model of the three-terminal adjustable voltage reference chip IC3 is TL431, which provides a reference voltage of 2.5V for the circuit.

The voltage dividing resistor includes a resistor R47 and a resistor R48, and the output current sampling circuit further includes a resistor R46 and an LED lamp, and the resistor R46 and the LED lamp are connected in series between the positive output terminal VO+ and the negative output terminal of the switching power supply, and There are multiple capacitors connected in parallel at the two ends of the positive output terminal and the negative output terminal, which are respectively capacitor C33, electrolytic capacitor C13, electrolytic capacitor C21, and electrolytic capacitor C22. The resistor R47 is connected in parallel with the resistor R48, and there are A plurality of capacitors, the capacitors are respectively electrolytic capacitor C18 and electrolytic capacitor C19.

The output current of the switching power supply flows through the current sampling resistor J1 to generate a negative voltage at point A, which is divided by resistor R39, resistor R34, and potentiometer VR2. The potential of the output terminal of IC4A drops below 0V, the potential of point C of the output terminal of the open-loop current amplifier rises to about 10V, and the delay circuit composed of capacitor C2 and resistor R40 charges the electrolytic capacitor C26, and the delay time of the charging circuit is determined by the resistor R40, electrolytic capacitor C26 and the comparison voltage 2.5V are determined. This program is set for 3-9 seconds. When the voltage at point D, that is, the positive electrode of electrolytic capacitor C26 reaches the reference voltage above 2.5V after charging (delay), the operational amplifier IC4B, The voltage comparator circuit composed of diode D12, diode D16 and resistor R49 outputs 6V at point E, that is, the output terminal of diode D12, and locks the voltage at point E through diode D16 and resistor R49, so that the current is output on the current sampling resistor J11 Continue to maintain the E point level after disappearing.

The above are only preferred embodiments of the utility model creation, and are not intended to limit the utility model creation. Any modifications, equivalent replacements and improvements made within the spirit and principles of the utility model creation should be included in the Within the scope of protection created by the utility model.

Claims (10)

1. A time-delay overcurrent shut-off circuit for elevator switching power supply, characterized in that it comprises a power supply circuit, a reference voltage circuit, an open-loop current amplification circuit, a charging current delay circuit, a voltage comparison circuit, and an output current sampling circuit , the output current sampling circuit includes a sampling resistor J1 and a voltage dividing resistor, the right end of the sampling resistor J1 is connected to the ground and the negative output terminal VO- of the switching power supply, and the left end is connected to the positive output terminal VO+ of the switching power supply through the voltage dividing resistor and connected to One end of the switching current amplification circuit is connected; The reference voltage circuit includes a power supply terminal, an output terminal, and a ground terminal, and the power supply terminal is connected to the output terminal of the power supply circuit; Described open-loop current amplifying circuit comprises operational amplifier IC4A, resistance R39, resistance R33, resistance R34, resistance R35, resistance R38, potentiometer VR2, and one end of described resistance R34 and one end of resistance R35 are connected with the output terminal of reference voltage circuit respectively Connection, the other end of the resistor R34 is connected to the negative input terminal of the operational amplifier IC4A, the other end of the resistor R35 is connected to the negative input terminal of the operational amplifier IC4A, the left end of the sampling resistor J1 passes through the resistor R39, the potentiometer VR2 and the negative input terminal of the operational amplifier IC4A. The input terminal is connected, and the positive input terminal of the operational amplifier IC4A is connected to the ground through the resistor R38; the output terminal of the operational amplifier IC4A is connected to the output terminal of the voltage comparison circuit through the charging current delay circuit, and the output terminal of the voltage comparison circuit is integrated with the control The pulse width of the circuit is connected to the chip pin. 2. A kind of time-delay overcurrent shut-off circuit for elevator switching power supply according to claim 1, is characterized in that, described charging current delay circuit comprises resistance R40, electric capacity C26, the output of described operational amplifier IC4A The terminal is connected to the right end of the resistor R40, and the left end of the resistor R40 is connected to the ground through the electrolytic capacitor C26. 3. A kind of time-delay overcurrent shut-off circuit for elevator switching power supply according to claim 2, is characterized in that, described voltage comparator circuit comprises operational amplifier IC4B, diode D12, diode D16, resistance R49, and described The left end of the resistor R40 is also connected to the positive input terminal of the operational amplifier IC4B, the output terminal of the operational amplifier IC4B is connected to the positive pole of the operational amplifier IC4B through the diode D16 and the resistor R49, and also connected to the input terminal of the diode D12, and the output terminal of the diode D12 serves as The output terminal of the voltage comparator circuit. 4. a kind of time-delay over-current shutdown circuit for elevator switching power supply according to claim 3, is characterized in that, described operational amplifier IC4A and operational amplifier IC4B form operational amplifier IC4, and the model of described operational amplifier IC4 for LM358. 5. A kind of delay overcurrent shut-off circuit for elevator switching power supply according to claim 1, is characterized in that, described power supply circuit comprises power supply chip IC2, electrolytic capacitor C14, the input end of power supply chip and external power supply The output terminal is connected to the power supply terminal of the reference voltage circuit and the positive pole of the electrolytic capacitor C14, and the negative pole of the electrolytic capacitor C14 is connected to the ground. 6. A time-delayed overcurrent shutdown circuit for an elevator switching power supply according to claim 5, wherein the model of the power chip IC2 is IM7812. 7. A kind of delay overcurrent shut-off circuit for elevator switching power supply according to claim 1, is characterized in that, described reference voltage circuit comprises resistor R33, three-terminal adjustable voltage reference chip IC3, electric capacity C27, One end of the resistor R33 is used as a power supply end, the other end is connected to the anode of the three-terminal adjustable voltage reference chip IC3 and used as the output end of the reference voltage circuit, the reference end is connected to the anode, the cathode is connected to the ground, and the capacitor C27 is connected in parallel to the three terminals Between the anode and cathode of the adjustable voltage reference chip IC3. 8. A time-delayed overcurrent shut-off circuit for an elevator switching power supply according to claim 7, wherein the model of the three-terminal adjustable voltage reference chip IC3 is TL431. 9. A time-delayed overcurrent shutdown circuit for an elevator switching power supply according to claim 7, wherein the delay time of the charging current delay circuit is 3-9 seconds. 10. A kind of time-delayed overcurrent shut-off circuit for elevator switching power supply according to claim 1, characterized in that, said voltage dividing resistor comprises resistor R47, resistor R48, and said output current sampling circuit further comprises resistor R46, LED lamp, the resistor R46 and the LED lamp are connected in series between the positive output terminal VO+ and the negative output terminal of the switching power supply, and a plurality of capacitors are connected in parallel at both ends of the positive output terminal and the negative output terminal, the resistor R47 and the resistor R48 connected in parallel, and a plurality of capacitors are connected in parallel at both ends of the resistor R47.