CN215870739U - Locked-rotor protection circuit of alternating current motor - Google Patents
Locked-rotor protection circuit of alternating current motor Download PDFInfo
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- CN215870739U CN215870739U CN202121577417.6U CN202121577417U CN215870739U CN 215870739 U CN215870739 U CN 215870739U CN 202121577417 U CN202121577417 U CN 202121577417U CN 215870739 U CN215870739 U CN 215870739U
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Abstract
The invention relates to the technical field of motors, in particular to an alternating current motor locked-rotor protection circuit which comprises a current sampling resistor, a coupling capacitor, a motor driving circuit, a conversion circuit and a control module, wherein the current sampling resistor is connected with the coupling capacitor; the current sampling resistor and the motor driving circuit are used for connecting the alternating voltage and the motor; the conversion circuit is used for generating a locked rotor detection signal with the same waveform as the alternating voltage according to the voltage difference between the two ends of the current sampling resistor; the control module is used for outputting a control signal when the peak value difference of the locked rotor detection signal is higher than the locked rotor threshold value, and controlling the motor driving circuit to disconnect the first driving end and the second driving end. This alternating current motor locked rotor protection circuit passes through coupling capacitance and converts alternating voltage into the low pressure locked rotor detection signal that can handle, replaces the fortune circuit in the past, simplifies circuit structure, reduction in production cost.
Description
Technical Field
The invention relates to the technical field of motors, in particular to an alternating current motor locked-rotor protection circuit.
Background
The food processor is a common food processor, the load of the food processor is mainly a motor, and a rotating shaft of the motor drives a blade to crush and stir food. During actual work, when food resistance is great, cause motor overload or stifled commentaries on classics easily, the electric current of motor sharply increases this moment, and serious meeting burns out the motor, causes the damage to the cooking machine. Therefore, it is necessary to detect the motor stalling and shut down the motor output control when overload or stalling occurs, thereby avoiding motor overcurrent damage.
In the prior art, an ac motor locked-rotor protection circuit at least comprises a motor, a motor driving circuit, a current sampling circuit, a signal conversion circuit and a main control circuit, and current signals flowing through the motor are converted into voltage signals through the current sampling circuits connected in series at two ends of the motor. However, the protection effect of the ac motor locked-rotor protection circuit cannot be adapted to the ac motor because the ac current signals at the two ends of the ac motor exceed the power supply range of the main control circuit, and therefore, the ac current signals need to be converted into voltage signals that can be processed by the main control circuit.
Disclosure of Invention
The present invention is directed to a locked-rotor protection circuit for an ac motor, which solves one or more of the problems of the prior art and provides at least one of the advantages of the present invention.
A locked-rotor protection circuit of an alternating current motor comprises a current sampling resistor, a coupling capacitor, a motor driving circuit, a conversion circuit and a control module;
one end of the current sampling resistor is connected with a first driving end of the motor driving circuit, a second driving end of the motor driving circuit is used for being connected with one input end of the alternating current motor, and the other end of the current sampling resistor and the other input end of the alternating current motor are used for being connected with alternating current voltage;
the conversion input end of the conversion circuit is connected with one end of the current sampling resistor through the coupling capacitor, the reference voltage end of the conversion circuit is connected with the other end of the current sampling resistor, and the reference voltage end is connected with a reference voltage signal and used for generating a locked rotor detection signal with the same waveform as the alternating current voltage according to the voltage difference between the two ends of the current sampling resistor;
the detection end of the control module is connected with the conversion output end of the conversion circuit, the control output end of the control module is connected with the control end of the motor driving circuit and used for outputting a control signal when the peak value difference of the locked rotor detection signal is higher than the locked rotor threshold value, and the motor driving circuit is controlled to disconnect the first driving end and the second driving end.
Further, the conversion circuit includes a first resistor and a second resistor;
one end of the coupling capacitor, far away from the current sampling resistor, is connected with one end of the first resistor, one end of the second resistor and one end of the third resistor respectively, the other end of the first resistor is grounded, and the other end of the second resistor is connected with the reference voltage signal.
Further, the conversion circuit further comprises a third resistor;
one end of the third resistor is connected with one end, far away from the current sampling resistor, of the coupling capacitor, and the other end of the third resistor is connected with the detection end of the control module.
Further, the motor driving circuit comprises a switching tube, a bidirectional thyristor and a fourth resistor;
the input end of the switch tube is connected with the trigger end of the bidirectional controllable silicon, the output end of the switch tube is grounded, and the control end of the switch tube is connected with the control output end of the control module; one end of the bidirectional controllable silicon is connected with the current sampling resistor and the trigger end of the bidirectional controllable silicon through the fourth resistor, and the other end of the bidirectional controllable silicon is used for being connected with the alternating current motor.
Further, the motor driving circuit comprises a fifth resistor, a sixth resistor and a seventh resistor;
the input end of the switch tube is connected with the trigger end of the bidirectional controllable silicon through a fifth resistor, the control end of the switch tube is connected with the control output end of the control module through a sixth resistor, and the seventh resistor is connected between the control end and the output end of the switch tube.
Further, the switching tube is an NPN type triode, a control end of the switching tube is a base electrode of the NPN type triode, an input end of the switching tube is a collector electrode of the NPN type triode, and an output end of the switching tube is an emitter electrode of the NPN type triode.
Further, the switch tube is an N-type field effect tube, the control end of the switch tube is the grid electrode of the N-type field effect tube, the input end of the switch tube is the drain electrode of the N-type field effect tube, and the output end of the switch tube is the source electrode of the N-type field effect tube.
Further, the control module is a single chip microcomputer.
The invention has the beneficial effects that: the coupling capacitor converts alternating voltage into a low-voltage locked rotor detection signal which can be processed, so that the conventional operational amplifier circuit is replaced, the circuit structure is simplified, and the production cost is reduced.
Drawings
Fig. 1 is a schematic diagram of an ac motor stall protection circuit according to a first embodiment.
Fig. 2 is a schematic diagram of a locked-rotor protection circuit for an ac motor according to a second embodiment.
Fig. 3 is a schematic diagram of a locked-rotor protection circuit for an ac motor according to a third embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the present invention will be further described with reference to the embodiments and the accompanying drawings.
Fig. 1 is a schematic diagram of an ac motor stall protection circuit according to a first embodiment.
As shown in fig. 1, the ac motor stall protection circuit includes a current sampling resistor Rs, a coupling capacitor C1, a motor driving circuit 100, a conversion circuit 200, and a control module 300, and is configured to cut off an input voltage when the ac motor enters stall, so as to achieve a protection effect.
The current sampling resistor Rs and the motor drive circuit 100 are connected to a voltage input circuit of the ac motor. Specifically, one end of the current sampling resistor Rs is connected to a first driving end of the motor driving circuit 100, a second driving end of the motor driving circuit 100 is used for being connected to one input end of the alternating current motor, and the other end of the current sampling resistor Rs and the other input end of the alternating current motor are used for receiving alternating current voltage. The current sampling resistor Rs collects current signals in the voltage input circuit, when the voltage input circuit is normally powered on, a voltage difference is formed at two ends of the current sampling resistor Rs, and the first driving end and the second driving end of the motor driving circuit 100 can be used as voltage input ends or output ends and can be regarded as a conducting wire.
The converting circuit 200 is used for feeding back the ac voltage condition of the voltage input circuit to the control module 300. Specifically, the conversion input terminal of the conversion circuit 200 is connected to one end of the current sampling resistor Rs through the coupling capacitor C1, the reference voltage vcc terminal of the conversion circuit 200 is connected to the other end of the current sampling resistor Rs, and the reference voltage vcc terminal is connected to the reference voltage vcc signal, and is configured to generate a locked rotor detection signal having the same waveform as the ac voltage according to the voltage difference across the current sampling resistor Rs.
The principle of generating the locked-rotor detection signal is based on the 'alternating current' characteristic of the coupling capacitor C1, the coupling capacitor C1 is connected in the voltage input circuit, the voltage connected to one end of the voltage input circuit gradually rises along with the rise of the voltage input circuit to gradually accumulate charges at the end, when the voltage of the voltage input circuit drops, the charges accumulated when the potential is high are returned to the circuit, and the released charges are combined with the input reference voltage vcc by receiving the accumulated and released charges of the coupling capacitor C1, so that the locked-rotor detection signal is formed.
Based on the locked-rotor detection signal, the control module 300 determines whether the motor driving circuit 100 needs to be turned off. Specifically, the detection end of the control module 300 is connected to the conversion output end of the conversion circuit 200, and the control output end of the control module 300 is connected to the control end of the motor driving circuit 100, and is configured to output a control signal when a peak difference of the locked rotor detection signal is higher than the locked rotor threshold value, and control the motor driving circuit 100 to disconnect the first driving end and the second driving end.
The principle of the control module 300 determining whether the motor driving circuit 100 needs to be turned off is: after the motor is locked, a large back electromotive force is generated at the moment of turning on the motor and exceeds the voltage peak value of the normal alternating voltage, the waveform of the locked rotor detection signal formed according to the alternating voltage also exceeds the normal peak value, and the control module 300 when receiving the locked rotor detection signal, collecting the value of each moment, and screening out the peak voltage VmaxAnd a trough voltage VminCalculating the peak voltage VmaxAnd a trough voltage VminAnd (3) judging whether the difference exceeds a peak value difference of a locked rotor detection signal converted from the output normal alternating voltage, if the exceeding times is detected to be more than a predetermined times, judging that the motor is locked, and disconnecting the input of the alternating voltage through the motor driving circuit 100.
Fig. 2 is a schematic diagram of a locked-rotor protection circuit for an ac motor according to a second embodiment.
As shown in fig. 2, on the basis of the above-described embodiment, the conversion circuit 200 of the present embodiment includes a first resistor R1, a second resistor R2, and a third resistor R3.
Specifically, one end of the coupling capacitor C1, which is far away from the current sampling resistor Rs, is connected to one end of the first resistor R1, one end of the second resistor R2, and one end of the third resistor R3, the other end of the first resistor R1 is grounded, and the other end of the second resistor R2 is connected to the reference voltage vcc signal. One end of the third resistor R3 is connected to the end of the coupling capacitor C1 away from the current sampling resistor Rs, and the other end of the third resistor R3 is connected to the detection end of the control module 300.
The reference voltage vcc flows to a signal ground after passing through the first resistor R1 and the second resistor R2, so that the locked rotor detection signal is an alternating current signal with the signal ground as a midpoint, the coupling capacitor C1 discharges charges from a common end of the first resistor R1 and the second resistor R2, the voltage value of the common end of the first resistor R1 and the second resistor R2 is changed to form the locked rotor detection signal, and finally the control module 300 acquires the locked rotor detection signal from the common end of the first resistor R1 and the second resistor R2 through the third resistor R3.
The motor driving circuit 100 according to this embodiment includes a switching tube Q1, a triac D1, and a fourth resistor R4.
Specifically, the input end of the switching tube Q1 is connected with the trigger end of the triac D1, the output end of the switching tube Q1 is grounded, and the control end of the switching tube Q1 is connected with the control output end of the control module 300; one end of the bidirectional thyristor D1 is connected with the current sampling resistor Rs and the trigger end of the bidirectional thyristor D1 through the fourth resistor R4, and the other end of the bidirectional thyristor D1 is used for being connected with the alternating current motor.
More specifically, the switching tube Q1 is an NPN type transistor, the control terminal of the switching tube Q1 is a base electrode of the NPN type transistor, the input terminal of the switching tube Q1 is a collector electrode of the NPN type transistor, and the output terminal of the switching tube Q1 is an emitter electrode of the NPN type transistor.
More specifically, the motor drive circuit 100 includes a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7; the input end of the switching tube Q1 is connected with the trigger end of the triac D1 through a fifth resistor R5, the control end of the switching tube Q1 is connected with the control output end of the control module 300 through a sixth resistor R6, and the seventh resistor R7 is connected between the control end and the output end of the switching tube Q1.
When the motor is locked, the control output end of the control module 300 outputs a control signal to the control end of the switching tube Q1, so that the switching tube Q1 is turned on, the level signal of the trigger end of the triac D1 is pulled down, and the two ends of the triac D1 connected to the voltage input circuit are disconnected, thereby disconnecting the input voltage.
In this embodiment, the control module 300 is a single chip.
Fig. 3 is a schematic diagram of a locked-rotor protection circuit for an ac motor according to a third embodiment.
As shown in fig. 3, in addition to the above embodiments, the switching transistor Q1 of this embodiment is an N-type fet, the control terminal of the switching transistor Q1 is the gate of the N-type fet, the input terminal of the switching transistor Q1 is the drain of the N-type fet, and the output terminal of the switching transistor Q1 is the source of the N-type fet.
As used herein, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, including not only those elements listed, but also other elements not expressly listed.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (8)
1. The alternating current motor locked rotor protection circuit is characterized by comprising a current sampling resistor, a coupling capacitor, a motor driving circuit, a conversion circuit and a control module;
one end of the current sampling resistor is connected with a first driving end of the motor driving circuit, a second driving end of the motor driving circuit is used for being connected with one input end of the alternating current motor, and the other end of the current sampling resistor and the other input end of the alternating current motor are used for being connected with alternating current voltage;
the conversion input end of the conversion circuit is connected with one end of the current sampling resistor through a coupling capacitor, the reference voltage end of the conversion circuit is connected with the other end of the current sampling resistor, and the reference voltage end is connected with a reference voltage signal and is used for generating a locked rotor detection signal with the same waveform as the alternating voltage according to the voltage difference between the two ends of the current sampling resistor;
the detection end of the control module is connected with the conversion output end of the conversion circuit, the control output end of the control module is connected with the control end of the motor driving circuit, and the control module is used for outputting a control signal when the peak value difference of the locked rotor detection signal is higher than the locked rotor threshold value, and controlling the motor driving circuit to disconnect the first driving end and the second driving end.
2. The ac motor stall protection circuit of claim 1, wherein the switching circuit comprises a first resistor and a second resistor;
one end of the coupling capacitor, far away from the current sampling resistor, is connected with one end of the first resistor, one end of the second resistor and one end of the third resistor respectively, the other end of the first resistor is grounded, and the other end of the second resistor is connected with the reference voltage signal.
3. The ac motor stall protection circuit of claim 2, wherein the switching circuit further comprises a third resistor;
one end of the third resistor is connected with one end, far away from the current sampling resistor, of the coupling capacitor, and the other end of the third resistor is connected with the detection end of the control module.
4. The ac motor stall protection circuit of claim 1, wherein the motor driving circuit comprises a switching tube, a triac, and a fourth resistor;
the input end of the switch tube is connected with the trigger end of the bidirectional controllable silicon, the output end of the switch tube is grounded, and the control end of the switch tube is connected with the control output end of the control module; one end of the bidirectional controllable silicon is connected with the current sampling resistor and the trigger end of the bidirectional controllable silicon through a fourth resistor, and the other end of the bidirectional controllable silicon is used for being connected with the alternating current motor.
5. The AC motor stall protection circuit of claim 4, wherein the motor drive circuit comprises a fifth resistor, a sixth resistor, and a seventh resistor;
the input end of the switch tube is connected with the trigger end of the bidirectional controllable silicon through a fifth resistor, the control end of the switch tube is connected with the control output end of the control module through a sixth resistor, and the seventh resistor is connected between the control end and the output end of the switch tube.
6. The AC motor stall protection circuit according to claim 4 or 5, wherein the switch tube is an NPN transistor, the control terminal of the switch tube is the base of the NPN transistor, the input terminal of the switch tube is the collector of the NPN transistor, and the output terminal of the switch tube is the emitter of the NPN transistor.
7. The AC motor stall protection circuit according to claim 4 or 5, wherein the switch tube is an NFET, the control terminal of the switch tube is the gate of the NFET, the input terminal of the switch tube is the drain of the NFET, and the output terminal of the switch tube is the source of the NFET.
8. The AC motor stall protection circuit of claim 1 wherein the control module is a single-chip microcomputer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121577417.6U CN215870739U (en) | 2021-07-12 | 2021-07-12 | Locked-rotor protection circuit of alternating current motor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121577417.6U CN215870739U (en) | 2021-07-12 | 2021-07-12 | Locked-rotor protection circuit of alternating current motor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN215870739U true CN215870739U (en) | 2022-02-18 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202121577417.6U Active CN215870739U (en) | 2021-07-12 | 2021-07-12 | Locked-rotor protection circuit of alternating current motor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN215870739U (en) |
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2021
- 2021-07-12 CN CN202121577417.6U patent/CN215870739U/en active Active
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