CN210669522U - Sectional voltage-reducing low-voltage direct current limiter - Google Patents

Abstract

The utility model relates to a segmentation step-down low pressure direct current limiter. The device comprises a singlechip, a BUCK voltage reduction circuit, a filter inductor, a main field effect transistor and an auxiliary field effect transistor; one end of the filter inductor is connected with the positive electrode of the input voltage, and the other end of the filter inductor is respectively connected with the D electrodes of the main field effect transistor and the auxiliary field effect transistor; the G pole of the main field effect transistor is connected with the D pole of the BUCK voltage reduction circuit, and the S pole of the main field effect transistor is connected with the positive pole of the output voltage of the BUCK voltage reduction circuit; the positive end of the filter inductor is connected with a current port of the single chip microcomputer through a current detection circuit, and two ends of the filter inductor are connected with an input voltage port of the single chip microcomputer through a voltage detection circuit; the G pole of the main field effect transistor and the G pole of the auxiliary field effect transistor are respectively connected with the PWM1 and PWM2 ports of the single chip microcomputer; the positive and negative electrodes of the output voltage are connected with the state detection port of the single chip microcomputer. The utility model discloses can guarantee certain output voltage in the current-limiting.

Description

Sectional voltage-reducing low-voltage direct current limiter

Technical Field

The utility model relates to a direct current limiter specifically is a segmentation step-down low pressure direct current limiter.

Background

When the direct current circuit has overload and short-circuit faults, the current in the circuit is suddenly increased, components such as a power supply, the circuit, a switch or a load can be damaged, the current limiter can limit the current on the premise of not disconnecting the power supply, the working state of the current circuit is kept as much as possible, and other circuits are not influenced.

Although the existing current limiter circuit can limit current or cut off the circuit, the size of output voltage cannot be guaranteed, only current indexes are concerned, and the voltage is reduced too much by limiting current output under most conditions, so that the failure of the existing circuit can be caused.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is to provide a segmentation step-down low pressure direct current limiter guarantees certain output voltage in the current-limiting.

The utility model provides a technical scheme that its technical problem adopted is:

a sectional voltage-reducing low-voltage direct current limiter comprises a single chip microcomputer, a BUCK voltage-reducing circuit, a filter inductor, a main field effect transistor and an auxiliary field effect transistor, wherein the filter inductor is used for detecting input voltage;

one end of the filter inductor is connected with the positive electrode of the input voltage, the other end of the filter inductor is respectively connected with the D electrodes of the main field effect transistor and the auxiliary field effect transistor, the G electrode of the main field effect transistor is connected with the D electrode of the BUCK voltage reduction circuit, and the S electrode of the main field effect transistor is connected with the positive electrode of the output voltage of the BUCK voltage reduction circuit;

the positive end of the filter inductor is connected with a current port of the single chip microcomputer through a current detection circuit, and the two ends of the filter inductor are connected with an input voltage port of the single chip microcomputer through a voltage detection circuit; the G pole of the main field effect transistor is connected with the PWM1 port of the single chip microcomputer, and the G pole of the auxiliary field effect transistor is connected with the PWM2 port of the single chip microcomputer; the positive and negative electrodes of the output voltage are connected with the state detection port of the single chip microcomputer, and the single chip microcomputer is connected with the audible and visual alarm.

Adopt above-mentioned technical scheme the utility model discloses, compare with prior art, beneficial effect is:

certain output voltage is ensured while current is limited, so that part of circuits can work normally when overcurrent occurs, and selective disconnection of a fault circuit is facilitated; the circuit breaking misoperation caused by instantaneous discharge or overvoltage can be protected, and the system stability is improved; performing sound and light prompt when a fault occurs; an intelligent monitoring network can be formed through the communication interface.

Drawings

Fig. 1 is a circuit diagram of an embodiment of the present invention.

Detailed Description

The invention is further described with reference to the following figures and examples.

Referring to fig. 1, the sectional BUCK low-voltage dc current limiter described in this embodiment is composed of a filter inductor L, a main field effect transistor MOSFET1, an auxiliary field effect transistor MOSFET2, a BUCK step-down circuit, a single chip microcomputer stm32f103c8t6, a current detection circuit, a voltage detection circuit, and an audible and visual alarm, wherein the current detection circuit adopts a 10A/3V hall sensor, and the voltage detection circuit adopts a proportional operational amplifier of an AD627 chip; the filter inductor L is used to detect the input voltage.

One end of a filter inductor L is connected with the positive electrode of input voltage, the filter inductor L is connected with the D electrode of a main field effect transistor MOSFET1 in series, the G electrode of a main field effect transistor MOSFET1 is connected with the D electrode of the BUCK voltage reduction circuit, and the S electrode of a main field effect transistor MOSFET1 is connected with the positive electrode of output voltage of the BUCK voltage reduction circuit;

the positive end of the filter inductor L is connected with a current port of the single chip microcomputer stm32f103c8t6 through a current detection circuit, and two ends of the filter inductor L are connected with an input voltage port of the single chip microcomputer stm32f103c8t6 through a voltage detection circuit; the G pole of the main field effect transistor MOSFET1 is connected with the PWM1 port of the single chip microcomputer stm32f103c8t6, and the G pole of the auxiliary field effect transistor MOSFET2 is connected with the PWM2 port of the single chip microcomputer stm32f103c8t 6; the positive and negative electrodes of the output voltage are connected with the state detection port of the single chip microcomputer stm32f103c8t6, and the single chip microcomputer stm32f103c8t6 is provided with an audible and visual alarm connection port.

The working process of the embodiment is as follows: the single chip microcomputer is used for collecting the output current value and the reverse voltage value on the filter inductor, the two values work normally when being smaller than the limit value, the main field effect transistor MOSFET1 is conducted, and the circuit works normally.

The reverse voltage value on the filter inductor is smaller than the limit value, the output current value is larger than the limit value, the circuit is indicated as load overload, the main field effect transistor MOSFET1 is closed, the auxiliary field effect transistor MOSFET2 is conducted, the BUCK voltage reduction circuit is started, the duty ratio of the driving circuit is controlled, the output voltage value is monitored, the output voltage is reduced to 85% of the normal working voltage, the output current value is judged after 0.2-2 seconds of delay (adjustable according to the load condition), and if the output current value is smaller than the limit value, the current working state is kept; if the current limit is larger than the current limit, the BUCK circuit is controlled to continuously reduce the voltage to 70% of the normal voltage and 55% of the normal voltage, and the detection is carried out again. If the voltage drops to 55% of the normal voltage and the output current exceeds the limit value, the auxiliary field effect transistor MOSFET2 is turned off, and the circuit is cut off.

If the reverse voltage value on the filter inductor is detected to exceed the limit value, the current in the circuit is increased sharply, inter-phase short circuit of the bus or short circuit of a certain device can occur, if the bus is short-circuited, overcurrent can be kept for a certain time, and if the device is short-circuited, the short-circuit current only occurs for a short time. After the reverse overvoltage is collected by the single chip microcomputer, delaying for 0.1-0.3 seconds, detecting whether overcurrent exists again, if overcurrent exists, cutting off the main field effect transistor MOSFET1 and the auxiliary field effect transistor MOSFET2, and cutting off the circuit; if not, the fault disappears and the circuit continues to operate normally. A corresponding warning circuit is arranged, and when a fault is found, an audible and visual alarm is used for giving an alarm; and an expansion interface is reserved, so that the fault information can be conveniently and reliably uploaded through an IO (input/output) port or an RS232 interface.

Because of the low voltage direct current circuit mostly uses electrical apparatus work at certain voltage range, also can work when voltage certain degree reduces, the utility model discloses adopt the method of sectional type step-down when detecting overflowing, reduce the power of electrical apparatus of load nature through the method of step-down, can effectually guarantee to keep the normal operating circuit of most low voltage direct current circuit when the overload capacity is not serious.

The above description is only a preferred and practical embodiment of the present invention, and not intended to limit the scope of the present invention, and all structural equivalents made by using the contents of the specification and drawings are included in the scope of the present invention.

Claims (1)

1. The utility model provides a segmentation step-down low pressure direct current limiter, includes singlechip, BUCK step-down circuit, its characterized in that: the filter inductor is used for detecting input voltage;

one end of the filter inductor is connected with the positive electrode of the input voltage, the other end of the filter inductor is respectively connected with the D electrodes of the main field effect transistor and the auxiliary field effect transistor, the G electrode of the main field effect transistor is connected with the D electrode of the BUCK voltage reduction circuit, and the S electrode of the main field effect transistor is connected with the positive electrode of the output voltage of the BUCK voltage reduction circuit;

the positive end of the filter inductor is connected with a current port of the single chip microcomputer through a current detection circuit, and the two ends of the filter inductor are connected with an input voltage port of the single chip microcomputer through a voltage detection circuit; the G pole of the main field effect transistor is connected with the PWM1 port of the single chip microcomputer, and the G pole of the auxiliary field effect transistor is connected with the PWM2 port of the single chip microcomputer; the positive and negative electrodes of the output voltage are connected with the state detection port of the single chip microcomputer, and the single chip microcomputer is connected with the audible and visual alarm.

Images