CN215817968U - Small-sized DC motor - Google Patents
Small-sized DC motor Download PDFInfo
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- CN215817968U CN215817968U CN202122004903.5U CN202122004903U CN215817968U CN 215817968 U CN215817968 U CN 215817968U CN 202122004903 U CN202122004903 U CN 202122004903U CN 215817968 U CN215817968 U CN 215817968U
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Abstract
The present disclosure provides a small-sized DC motor including an armature circuit and a start-up protection circuit connected in series in the armature circuit. The start-up protection circuit includes: the variable resistor is connected with an external control system; the first contactor is connected with the variable resistor in parallel; and the time relay is connected with the first contactor. According to the starting protection circuit for starting the small-sized direct-current motor, the variable resistor is connected in series in the armature loop, so that the starting current can be limited within a certain allowable value in the starting process of the motor, huge disturbance and impact on a corresponding circuit and switch equipment are avoided, the circuit tripping accident is avoided, and the operation is safer.
Description
Technical Field
The present disclosure relates to motor control technologies, and in particular, to a small dc motor.
Background
The motors are closely related to human life and inseparable, and two types of motors commonly used in industrial production are alternating current motors and direct current motors. The alternating current motor is reliable in operation, low in cost, wide in application range and more applicable to industrial and agricultural production. The direct current motor has the advantages of large speed regulation range, easy control, high speed performance, capability of adapting to frequent starting and the like, and is suitable for places such as large-scale precision machine tools, mine windlasses, trolleybuses and the like or used as a standby motor of an alternating current motor for important equipment. The emergency oil pump of a turbine lubrication system in a power plant is usually a small dc motor.
The armature loop resistance and inductance of a small-sized DC motor are small, and the rotor has a certain mechanical inertia. Therefore, in practical use, after the direct current motor is powered on, the armature rotating speed and the corresponding back electromotive force are very small at the initial stage of starting, so that the starting current can reach 15-20 times of the rated current, and the overlarge starting current can cause huge disturbance and impact on corresponding circuits and switch equipment, so that circuit tripping accidents can be caused frequently, and a great risk is caused to operation.
SUMMERY OF THE UTILITY MODEL
In view of the above, the present disclosure is directed to a small dc motor to solve or partially solve the problem of large starting current.
In view of the above object, the present disclosure provides a small dc motor including: an armature circuit connected between the DC power supply wiring terminals; a start-up protection circuit connected in series in the armature circuit, the start-up protection circuit comprising:
the variable resistor is connected with an external control system;
the first contactor is connected with the variable resistor in parallel;
optionally, the start-up protection circuit further comprises: and the time relay is connected with the first contactor.
Optionally, the magnetic circuit further comprises a field coil connected between the direct current power supply terminals, and the field coil is located near the armature in the armature circuit.
Optionally, the detection circuit is connected in series between the variable resistor and a positive terminal of the dc power terminals.
Optionally, the detection loop includes a shunt, a dc ammeter, and a dc transmitter connected in parallel in sequence.
Optionally, the shunt is connected in series between the variable resistor and a positive terminal of the dc power terminals, and the dc current transmitter is connected to an external control system.
Optionally, the armature circuit further includes a thermal relay, a first end of the thermal relay is connected to the variable resistor, a second end of the thermal relay is connected to the input end of the armature, a third end of the thermal relay is connected to the output end of the armature, and a fourth end of the thermal relay is connected to a negative terminal of the dc power terminals.
Optionally, a first dc contactor is further connected between the variable resistor and a positive terminal of the dc power source terminals, and a second dc contactor is further connected between the output end of the armature and a negative terminal of the dc power source terminals.
As can be seen from the above, the small-sized dc motor provided by the present disclosure, by serially connecting the variable resistor in the armature loop, can limit the starting current within a certain allowable value in the starting process of the motor, thereby avoiding causing huge disturbance and impact to the corresponding circuit and switching equipment, avoiding causing circuit tripping accidents, and having safer operation; meanwhile, the total resistance in the whole circuit can be adjusted by adjusting the resistance value of the variable resistor, so that the starting current can be adjusted according to actual conditions, the circuit tripping accident can be avoided, the starting time of the motor can be guaranteed to meet requirements, the motor is flexibly applicable to various motors, and the motor is high in flexibility and wide in application range.
Drawings
In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is an electrical schematic diagram of a small dc motor according to an embodiment of the present disclosure.
List of reference numerals in fig. 1: 1. a detection circuit; 2. an armature circuit; 3. an excitation loop; DC. A direct current power supply; QF, dc circuit breakers; KM1, a first DC contactor; KM2, a second direct current contactor; KM3, a first contactor; r, variable resistance; FL, shunt; A. a direct current ammeter; DLB, dc current transducer; FR, thermal relay.
Detailed Description
For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.
It is to be noted that technical terms or scientific terms used in the embodiments of the present disclosure should have a general meaning as understood by those having ordinary skill in the art to which the present disclosure belongs, unless otherwise defined. The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather is used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
As shown in fig. 1, the present disclosure provides a small-sized dc motor including an armature circuit 2 and a start-up protection circuit connected in series in the armature circuit 2. The start-up protection circuit may include:
the variable resistor R is connected with an external control system;
the first contactor KM3 is connected with the variable resistor R in parallel;
and the time relay is connected with the first contactor KM 3.
Specifically, the armature circuit 2 includes an armature connected between dc power supply terminals. The small-sized dc motor may further include an excitation circuit 3, and the excitation circuit 3 includes an excitation coil connected between dc power supply terminals, the excitation coil being located near an armature in the armature circuit 2. In operation, the armature is located within the magnetic field generated by the field coil.
The variable resistor R is connected with an external control system, and the external control system is used for adjusting the resistance value of the variable resistor R. Before the motor is started, the resistance value of the variable resistor R is adjusted to be maximum, the exciting voltage is added, the exciting current is kept to be a rated value and is unchanged, then the armature power supply is switched on, and the motor starts. The external control system controls the resistance value of the variable resistor R to gradually decrease with the increase of the rotating speed until all the resistors are cut off. Then, the first contactor KM3 was controlled to be closed by using a time relay, and the first contactor KM3 short-circuited the variable resistor R.
Specifically, the dc motor is composed of a stator (stationary) and a rotor (rotating), and a gap, called an air gap, is formed between the stator and the rotor. The stator part comprises a main magnetic pole, a commutating pole, an electric brush, a base and the like. The main magnetic pole is used for generating an air gap magnetic field and consists of an iron core and an excitation coil. And introducing direct current into the excitation coil to form a magnetic field. The rotor portion includes an armature core, an armature winding (i.e., an armature as described in this disclosure), a commutator, a rotating shaft, a fan, and the like.
The dc motor can be classified into a large, medium and small dc motor according to specification and size. According to the relevant standard, the motor with the outer diameter of the armature core more than 990mm is a large-scale direct current motor; the motor with the armature core outer diameter of 368-990 mm is a medium-sized direct current motor; the motor with a center height of 400mm or less or an armature core outer diameter of 368mm or less is a small-sized DC motor.
In actual use, at the moment when the small dc motor is started, the motor speed and the back electromotive force are both zero, and the current in the armature circuit 2 is at a maximum. Therefore, the starting protection circuit disclosed by the disclosure can effectively limit the starting current in the armature circuit 2, and the specific process is as follows:
(1) the magnitude of the starting current applied to the motor is calculated from the magnitude of the rated current of the small-sized DC motor. The starting current is generally 1.5-2.0 times the rated current, usually based on double considerations of safety and starting time.
(2) The calculated resistance value of the variable resistor R applied to the motor is calculated from the calculated magnitude of the starting current, and then the resistance value of the variable resistor R in the motor is adjusted to the calculated resistance value.
(3) Before starting, the first contactor is in an off state, and the resistance value of the variable resistor R is adjusted to be maximum. The power supply of the excitation circuit 3 is switched on, the excitation voltage is added, the excitation current is kept constant at a rated value, and then the power supply of the armature circuit 2 is switched on. At the moment when the armature circuit 2 starts to be electrified, namely the small-sized direct current motor is started, the rotating speed and the back electromotive force of the motor are both zero, the current in the armature circuit 2 is maximum at the moment, and the maximum current for starting is
Wherein IstMaximum current for start-up, RaIs a resistance in the armature circuit 2, R is a resistance value of a variable resistor R, UNIs the total voltage in the armature circuit 2.
At the moment of energization, the field coil in the field circuit 3 generates a magnetic field after energization, and since the armature is located in the magnetic field generated by the field coil, the energized armature generates a rotating force under the action of the magnetic field, and further the armature starts to rotate, at which time the motor starts to rotate.
(4) After the motor rotates, the starting current is gradually reduced along with the increase of the rotating speed and the counter electromotive force, the resistance value of the variable resistor R can be gradually reduced, after a period of starting time, the rotating speed and the counter electromotive force are increased to preset values, the starting current is also reduced to the preset values, huge disturbance and impact can not be caused to corresponding circuits and switch equipment, and circuit tripping accidents can not be caused. At this time, the first contactor KM3 was closed by the time relay, and the closed first contactor KM3 shorted the variable resistor R, and the total resistance in the circuit decreased and the current increased, but not increased to the extent of striking the circuit.
Therefore, by serially connecting the variable resistor R into the armature loop 2, the starting current can be limited within a certain allowable value in the starting process of the motor, so that huge disturbance and impact on corresponding circuits and switch equipment are avoided, the circuit tripping accident is avoided, and the operation is safer; meanwhile, the total resistance in the whole circuit can be adjusted by adjusting the resistance value of the variable resistor R, so that the starting current can be adjusted according to actual conditions, the circuit tripping accident can be avoided, the starting time of the motor can be guaranteed to meet requirements, the motor is flexibly applicable to various motors, and the motor is high in flexibility and wide in application range.
The addition of the variable resistor R can be used for installing new equipment, and a solution is provided for faults of tripping starting of a motor of the direct current equipment in an operating power plant, unsatisfied starting time and the like.
Meanwhile, after the starting current of the motor is reduced to a safe range, the variable resistor R is in short circuit, so that the armature loop 2 is not connected with the variable resistor R in series any more, and the armature loop 2 is prevented from being connected with a large resistor in series for a long time to cause large energy loss.
In addition, in the disclosure, the opening and closing of the first contactor KM3 are controlled through the time relay, and the first contactor KM3 is controlled to be opened or closed at a specific time by setting the specific time for the time relay, so that the starting time of the motor can meet the starting requirement, and the situation that the starting time is too long cannot be caused.
In practical application, if the resistor connected in series in the armature circuit is not properly selected, great influence can be caused, and if the resistor is too small, the starting current is too large, so that tripping is caused when the motor is started; if the resistance is too large, the starting time of the motor can be caused to be not satisfactory. Therefore, the variable resistor R is added into the armature loop 2, the total resistance in the whole circuit is adjusted by adjusting the resistance value of the variable resistor R, and then the starting current can be adjusted according to the actual condition, so that the accident of circuit tripping can be avoided, and the starting time of the motor can be ensured to meet the requirement.
For a small direct current motor (such as a direct current lubricating oil pump motor) which does not need uniform and smooth stepless speed regulation, the starting current is controlled within a certain range only when the small direct current motor is started, the damage of the motor or idle trip caused by overlarge current is avoided, and the motor can reach the rated rotating speed within the specified time.
In some embodiments, the small DC motor further comprises a detection circuit 1, wherein the detection circuit 1 comprises a shunt FL, a DC current meter a and a DC current transmitter DLB connected in parallel in sequence, the shunt FL is connected in series between the variable resistor R and the DC power supply DC positive terminal, and the DC current transmitter DLB is connected with an external control system.
Specifically, the detection loop 1 is used for detecting the current in the armature loop 2, and the direct current transmitter DLB can directly convert the current in the detected armature loop 2 into a DC4-20mA constant current loop standard signal which is output in a linear proportion, and continuously transmit the signal to an external control system (such as a computer or a display instrument).
The setting through detection return circuit 1 makes relevant personnel can look over the size of current in armature return circuit 2 through external control system rapidly, and then makes the degree of automation of whole device higher.
In some embodiments, the armature circuit 2 further includes a thermal relay FR, a first terminal of which is connected to the variable resistor R, a second terminal of which is connected to the input terminal of the armature, a third terminal of which is connected to the output terminal of the armature, and a fourth terminal of which is connected to the DC negative terminal of the DC power supply.
Specifically, the thermal relay FR protects the armature circuit 2. When the heat generated by the overlarge current in the armature circuit 2 is too much, the thermal relay FR automatically disconnects the armature circuit 2, so that the circuit is protected, and the whole circuit and the motor are safer to use.
In some embodiments, a first direct current contactor KM1 is further connected between the variable resistor R and the positive terminal of the direct current power supply DC, and a second direct current contactor KM2 is further connected between the output end of the armature and the negative terminal of the direct current power supply DC.
Specifically, the arrangement of the first dc contactor KM1 and the second dc contactor KM2 makes the connection of the entire armature circuit 2 and the power supply more convenient and the operation simpler.
Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the present disclosure, features in the above embodiments or in different embodiments may also be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the present disclosure as described above, which are not provided in detail for the sake of brevity.
The embodiments of the present disclosure are intended to embrace all such alternatives, modifications and variances that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalents, improvements, and the like that may be made within the spirit and principles of the disclosure are intended to be included within the scope of the disclosure.
Claims (7)
1. A miniature dc motor comprising:
an armature circuit connected between the DC power supply wiring terminals;
a start-up protection circuit connected in series in the armature circuit,
wherein the start-up protection circuit comprises:
the variable resistor is connected with an external control system;
and the first contactor is connected with the variable resistor in parallel.
2. The small dc motor according to claim 1, wherein the start-up protection circuit further comprises: and the time relay is connected with the first contactor.
3. The small direct current motor according to claim 1 or 2, further comprising a field circuit connected between the direct current power supply terminals, the field circuit including a field coil, the field coil being located near an armature in the armature circuit.
4. The small-sized direct current motor according to claim 1 or 2, further comprising a detection circuit connected in series between the variable resistor and a positive terminal of the direct current power supply terminals.
5. The small direct current motor according to claim 4, wherein the detection circuit is connected to the external control system.
6. The small-sized direct current motor according to claim 1 or 2, wherein a thermal relay is included in the armature circuit, and a first terminal of the thermal relay is connected to the variable resistor, a second terminal thereof is connected to an input terminal of an armature in the armature circuit, a third terminal thereof is connected to an output terminal of the armature, and a fourth terminal thereof is connected to a negative terminal of the direct current power supply terminals.
7. The small-sized direct current motor according to claim 1 or 2, further comprising:
the first direct current contactor is connected in series between the variable resistor and a positive connecting terminal of the direct current power supply connecting terminals;
and the second direct current contactor is connected between the output end of the armature in the armature circuit and a negative connecting terminal in the direct current power supply connecting terminals in series.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202122004903.5U CN215817968U (en) | 2021-08-24 | 2021-08-24 | Small-sized DC motor |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202122004903.5U CN215817968U (en) | 2021-08-24 | 2021-08-24 | Small-sized DC motor |
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| CN215817968U true CN215817968U (en) | 2022-02-11 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023197704A1 (en) * | 2022-04-15 | 2023-10-19 | 北京长木谷医疗科技有限公司 | Monitoring method and device for intelligent osteotomy system of surgical robot |
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2021
- 2021-08-24 CN CN202122004903.5U patent/CN215817968U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023197704A1 (en) * | 2022-04-15 | 2023-10-19 | 北京长木谷医疗科技有限公司 | Monitoring method and device for intelligent osteotomy system of surgical robot |
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Inventor after: Bai Jincai Inventor after: Bu Qingguo Inventor after: Zhang Jiangjun Inventor after: Hu Bo Inventor after: Xie Jiarui Inventor before: Bai Jincai Inventor before: Zeng Wuqing Inventor before: Bu Qingguo Inventor before: Zhang Jiangjun Inventor before: Hu Bo Inventor before: Xie Jiarui |
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