CN211183392U - Protection circuit of single-phase alternating current motor - Google Patents

Abstract

The utility model discloses a protection circuit for a single-phase AC motor capable of comprehensively protecting the single-phase AC motor, comprising: a working power supply, an overvoltage and undervoltage sampling circuit, an overheating sampling circuit, and an overcurrent sampling circuit. The sampling circuit includes: transformer, half-wave rectifier diode, charging capacitor, overvoltage and undervoltage output resistor, pull-down resistor, overvoltage and undervoltage output filter capacitor, power supply side diode, ground side diode and upper and lower limit voltage divider resistors, the primary of the transformer The coil is connected to alternating current, the phase line of the secondary coil of the transformer with the same name is connected to the positive electrode of the half-wave rectifier diode, the negative electrode of the half-wave rectifier diode is connected to the corresponding end of the charging capacitor, and the upper and lower limit voltage divider resistors are connected in series in sequence and then grounded. , the connected ends of the upper and lower limit voltage divider resistors are used as overvoltage and undervoltage output ends, and are connected with one end of the pull-down resistor, the corresponding end of the filter capacitor at the overvoltage and undervoltage output ends, the anode of the power-side diode, and the cathode of the ground-side diode. . The protection circuit of the single-phase AC motor of the present invention can be widely used in various single-phase AC motors.

Description

A protection circuit for a single-phase AC motor

technical field

The utility model relates to a protection circuit of a motor, in particular to a protection circuit of a single-phase alternating current motor.

Background technique

At present, the structure of the protection circuit of the traditional hand-held threading machine is relatively simple, usually only a fuse (fuse) connected in series in the power supply circuit of the AC motor. Therefore, the AC motor cannot be fully protected, and the service life of the AC motor is shortened.

Utility model content

The technical problem to be solved by the utility model is to provide a protection circuit for a single-phase AC motor that can protect the AC motor in all directions.

In order to solve the above-mentioned technical problems, the technical scheme adopted by the present invention is: a protection circuit for a single-phase AC motor, comprising: a working power supply, an overvoltage and undervoltage sampling circuit, an overheating sampling circuit, and an overcurrent sampling circuit, wherein the overvoltage and undervoltage sampling circuits are used. The specific structure of the sampling circuit includes: transformer, half-wave rectifier diode, charging capacitor, overvoltage and undervoltage output resistor, pull-down resistor, overvoltage and undervoltage output filter capacitor, power supply side diode, ground side diode and upper and lower limit voltage divider resistors , the primary coil of the transformer is connected to the alternating current, the phase line of the secondary coil of the transformer with the same name is connected to the positive electrode of the half-wave rectifier diode, and the negative electrode of the half-wave rectifier diode is connected to one end of the upper limit voltage divider resistor. The other end of the upper limit voltage dividing resistor is connected with one end of the lower limit voltage dividing resistor and the corresponding end of the charging capacitor, the other end of the charging capacitor and the other end of the lower limit voltage dividing resistor are grounded, and the upper and lower limit voltage dividing resistors The connected end of the 10000 is used as the overvoltage and undervoltage output end, one end of the pull-down resistor, the corresponding end of the filter capacitor of the overvoltage and undervoltage output end, the positive electrode of the power supply side diode, and the negative electrode of the grounding side diode are connected to the overvoltage and undervoltage output end, the pull-down resistor The other end of the overvoltage and undervoltage output filter capacitors, the cathode of the diode on the power supply side, and the anode of the diode on the grounding side are grounded.

As a preferred solution, in the protection circuit of the single-phase AC motor, the specific structure of the overcurrent sampling circuit includes: a current transformer, and a ninth filter capacitor is connected in parallel between two output ends of the current transformer , the nineteenth resistor, and the corresponding end of the current transformer is provided with a capacitor to ground, and an overcurrent output resistor is connected in series as an overcurrent output terminal, and the other end of the current transformer is grounded.

As a preferred solution, in the protection circuit of the single-phase AC motor, the protection circuit further includes a ninth transient diode, the cathode of the ninth transient diode is connected to the corresponding end of the current transformer, and the ninth transient diode is connected to the corresponding end of the current transformer. The anodes of the nine transient diodes are grounded.

As a preferred solution, in the protection circuit of the single-phase AC motor, the specific structure of the overheat sampling circuit includes: a temperature sensor, the corresponding end of the temperature sensor is used as an overheat output end, and the other end is grounded, and the overheating The output end is provided with a twenty-first resistor and an eleventh filter capacitor to the ground.

As a preferred solution, in the protection circuit of the single-phase AC motor, the protection circuit further includes a tenth transient diode, and the negative electrode of the tenth transient diode is connected to the overheating output end, and the tenth transient diode is connected to the overheating output terminal. The anodes of ten transient diodes are grounded.

As a preferred solution, in the protection circuit of the single-phase AC motor, both ends of the charging capacitor are also connected in parallel with a charging filter capacitor.

The beneficial effects of the utility model are: the utility model provides all-round protection for the AC motor by setting the over-voltage sampling circuit, the under-voltage sampling circuit, the over-temperature sampling circuit and the over-current sampling circuit, so that the AC motor will not be damaged due to sudden abnormality. damage, greatly extending the life of the AC motor. In addition, the over-voltage and under-voltage sampling circuits, the over-temperature sampling circuits and the over-current sampling circuits adopted in the present invention have simple and practical structures, which greatly reduces the cost and increases the market competitiveness.

Description of drawings

FIG. 1 is a schematic structural diagram of the electrical principle of the protection circuit of the single-phase AC motor according to the present invention.

Detailed ways

The specific implementation of the protection circuit of a single-phase AC motor according to the present utility model will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, the protection circuit of a single-phase AC motor according to the present utility model has a structure including: a working power supply VCC5, an overvoltage and undervoltage sampling circuit, an overheating sampling circuit, and an overcurrent sampling circuit. The specific structure of the sampling circuit includes: transformer T1 (multiplexed with the power supply circuit), half-wave rectifier diode D3, charging capacitor C6, overvoltage and undervoltage output resistor R9, pull-down resistor R10, overvoltage and undervoltage output filter capacitor C8, and power supply side Diode D5, ground side diode D6, upper limit voltage divider resistor R7 and lower limit voltage divider resistor R8, both ends of the primary coil of transformer T1 are respectively connected to LIN and NIN of AC power, and the phase line of the secondary coil of transformer T1 ( LIN) The same name terminal is connected to the positive pole of the half-wave rectifier diode D3, the negative pole of the half-wave rectifier diode D3 is connected to one end of the upper limit voltage divider resistor R7, and the other end of the upper limit voltage divider resistor R7 is connected to the lower limit voltage divider resistor. One end of R8 is connected to the corresponding end of the charging capacitor C6, and the two ends of the charging capacitor C6 are also connected in parallel with a charging filter capacitor C7. The other end of the charging capacitor C6 and the other end of the lower limit voltage divider resistor R8 are grounded. The connected terminals of the bit voltage divider resistors R7 and R8 are used as the over- and under-voltage output terminals, which are connected with one end of the pull-down resistor R10, the corresponding terminal of the filter capacitor C8 at the over- and under-voltage output terminals, the positive pole of the power-side diode D5, and the ground-side diode D6. , the other end of the pull-down resistor R10, the other end of the filter capacitor C8 at the over-under-voltage output end, the cathode of the power-side diode D5, and the anode of the ground-side diode D6 are grounded; the specific structure of the over-current sampling circuit includes: a current transformer ( It belongs to the conventional technology in the art, not shown in the figure) and the ninth transient diode D9, and the two output ends of the current transformer pass through the plug CT and the corresponding socket (belonging to the conventional technology in the art, not shown in the figure). output) are connected in parallel with the ninth filter capacitor C9 and the nineteenth resistor R19, the corresponding end of the current transformer is provided with a grounding capacitor C10, and an overcurrent output resistor R20 is connected in series as the overcurrent output terminal, and the other end of the current transformer One end is grounded through the plug TEMP, the negative electrode of the ninth transient diode D9 is connected to the corresponding end of the current transformer, and the positive electrode of the ninth transient diode D9 is grounded; the specific structure of the overheat sampling circuit includes: a temperature sensor (belonging to this Conventional technology in the field, not shown in the figure), tenth transient diode D10, the temperature sensor uses its corresponding end as the overheat output end through the plug TEMP and the corresponding socket (belonging to the conventional technology in the art, not shown in the figure) , ground the other end, the overheating output end D10 is provided with a twenty-first resistor R21 and an eleventh filter capacitor C11 to the ground, the negative electrode of the tenth transient diode D10 is connected to the overheating output end, and the first The anode of ten transient diode D10 is grounded.

To sum up, it is only a preferred embodiment of the present utility model, and is not intended to limit the scope of the present utility model. and modifications should be included within the scope of the claims of the present invention.

Claims (6)

1. A protection circuit for a single-phase AC motor, comprising: a working power supply, characterized in that the protection circuit further comprises: an overvoltage and undervoltage sampling circuit, an overheating sampling circuit, and an overcurrent sampling circuit, wherein the overvoltage and undervoltage sampling circuit The specific structure of the circuit includes: a transformer, a half-wave rectifier diode, a charging capacitor, an overvoltage and undervoltage output resistor, a pull-down resistor, a filter capacitor at the overvoltage and undervoltage output terminals, a power-side diode, a ground-side diode, and upper and lower limit voltage divider resistors. The primary coil of the transformer is connected to the alternating current, the phase line of the secondary coil of the transformer with the same name is connected to the positive electrode of the half-wave rectifier diode, and the negative electrode of the half-wave rectifier diode is connected to one end of the upper limit voltage divider resistor. The other end of the voltage divider resistor is connected to one end of the lower limit voltage divider resistor and the corresponding end of the charging capacitor, the other end of the charging capacitor and the other end of the lower limit voltage divider resistor are grounded, and the upper and lower limit voltage divider resistors are connected to the ground. The connected terminal is used as the over- and under-voltage output terminal. One end of the pull-down resistor, the corresponding terminal of the filter capacitor at the over- and under-voltage output terminal, the anode of the power-side diode, and the cathode of the ground-side diode are connected to the over-under-voltage output terminal. The other end, the other end of the filter capacitor at the overvoltage and undervoltage output end, the cathode of the diode on the power supply side, and the anode of the diode on the grounding side are grounded. 2. The protection circuit of a single-phase AC motor according to claim 1, wherein the specific structure of the overcurrent sampling circuit comprises: a current transformer, and two output ends of the current transformer are connected in parallel with each other. The ninth filter capacitor, the nineteenth resistor, and the corresponding end of the current transformer are provided with a grounding capacitor, and an overcurrent output resistor is connected in series as an overcurrent output end, and the other end of the current transformer is grounded. 3 . The protection circuit of a single-phase AC motor according to claim 2 , wherein the protection circuit further comprises a ninth transient diode, and the cathode of the ninth transient diode corresponds to the current transformer. 4 . The terminals are connected, and the anode of the ninth transient diode is grounded. 4. The protection circuit of a single-phase AC motor according to claim 1, wherein the specific structure of the overheat sampling circuit comprises: a temperature sensor, the corresponding end of the temperature sensor is used as an overheat output end, and the other end is grounded, The overheated output end is provided with a twenty-first resistor and an eleventh filter capacitor to the ground. 5 . The protection circuit of a single-phase AC motor according to claim 4 , wherein the protection circuit further comprises a tenth transient diode, and the negative electrode of the tenth transient diode is connected to the overheat output. 6 . The terminals are connected, and the anode of the tenth transient diode is grounded. 6 . The protection circuit for a single-phase AC motor according to claim 1 , wherein a charging filter capacitor is connected in parallel with both ends of the charging capacitor. 7 .

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