CN212210877U - AC brushless electric tool - Google Patents
AC brushless electric tool Download PDFInfo
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- CN212210877U CN212210877U CN202020926864.7U CN202020926864U CN212210877U CN 212210877 U CN212210877 U CN 212210877U CN 202020926864 U CN202020926864 U CN 202020926864U CN 212210877 U CN212210877 U CN 212210877U
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Abstract
An AC brushless electric tool includes a housing, and a motor, a controller and a drive module disposed inside the housing; the driving module is provided with a driving circuit and an inverter circuit; the controller controls the operation of the motor through the driving module; the alternating current brushless electric tool is connected with an alternating current power supply, the alternating current power supply is electrically connected to the inverter circuit after passing through the rectifying circuit to supply power to the motor, the rectifying circuit is electrically connected with the voltage transformation module, and the voltage transformation module is electrically connected with the controller; the alternating current brushless electric tool comprises a motor, a controller and a driving circuit, wherein the motor is electrically connected with a rotating speed detection module, the rotating speed detection module detects the real-time rotating speed of the motor and transmits the real-time rotating speed to the controller, the controller stores preset rotating speeds, and the controller controls the duty ratio of the inverter circuit through the driving circuit according to the difference value of the real-time rotating speed relative to the preset rotating speeds, so that the output of the alternating current brushless electric tool is more stable.
Description
[ technical field ]
The utility model relates to an electric tool technical field, in particular to exchange brushless electric tool with stable output.
[ background art ]
Compared with the electric tool powered by a direct-current power supply, the electric tool powered by the alternating-current power supply has the advantages of no electric quantity limitation and higher power, so that the alternating-current power supply is widely applied to various tools.
Please refer to chinese invention patent CN108233784B, published on 07/04/2020, which states that the rectified pulsating voltage is detected by the voltage acquisition module, and the duty ratio of the switching tube is adjusted according to the pulsating voltage to achieve the purpose of stabilizing the output of the motor.
Accordingly, there is a need for an ac brushless power tool that overcomes the shortcomings of the prior art.
[ contents of utility model ]
To the deficiency of the prior art, an object of the utility model is to provide an exchange brushless electric tool, this exchange brushless electric tool's output is more steady.
The utility model provides a technical scheme that prior art problem adopted is: the alternating current brushless electric tool comprises a shell, and a motor, a controller and a driving module which are arranged in the shell; the motor is connected with an output module, and the output module transmits the energy of the motor to an external load; the driving module is provided with a driving circuit and an inverter circuit, and the driving circuit controls the duty ratio of the inverter circuit; the controller controls the operation of the motor through the driving module; the alternating current brushless electric tool is powered by an alternating current power supply, the alternating current power supply is electrically connected to the inverter circuit after passing through the rectifying circuit, the inverter circuit is electrically connected to the motor to supply power to the motor, the rectifying circuit is electrically connected with the voltage transformation module, and the voltage transformation module converts high-voltage direct current output by the rectifying circuit into low-voltage direct current to supply power to the controller; the motor is electrically connected with a rotating speed detection module, the rotating speed detection module detects the real-time rotating speed of the motor and transmits the real-time rotating speed to the controller, a preset rotating speed is stored in the controller, the controller controls the duty ratio of the inverter circuit through the driving circuit according to the difference value of the real-time rotating speed relative to the preset rotating speed, and the larger the duty ratio of the inverter circuit is, the higher the real-time rotating speed is.
Preferably, a preset difference value is stored in the controller; when the real-time rotating speed is lower than the preset rotating speed, the controller controls the duty ratio of the inverter circuit to be increased to a value higher than the current duty ratio through the driving circuit, so that the absolute value of the difference value between the real-time rotating speed of the motor and the preset rotating speed is not more than the preset difference value.
Preferably, a preset difference value is stored in the controller; when the real-time rotating speed is greater than the preset rotating speed, the controller controls the duty ratio of the inverter circuit to be reduced to a value lower than the current duty ratio through the driving circuit, so that the absolute value of the difference value between the real-time rotating speed of the motor and the preset rotating speed is not more than the preset difference value.
Preferably, the rotation speed detection module comprises a back electromotive force detection circuit, and the back electromotive force detection circuit is provided with a voltage comparator; the motor is a brushless motor, the brushless motor comprises a rotor, a stator core and a stator coil, the rotor is connected with the output module, the stator coil is electrically connected to the positive pole of the input end of the voltage comparator through a divider resistor, the negative pole of the input end of the voltage comparator is grounded, the output end of the voltage comparator is electrically connected to the controller, the positive pole of the input end of the voltage comparator detects the back electromotive force of the stator coil and compares the back electromotive force with the negative pole voltage of the input end of the voltage comparator, the output end of the voltage comparator outputs a comparison signal to the controller, and the controller determines the real-time rotating speed according to the comparison signal.
Preferably, the motor is a brushless motor, the brushless motor includes a rotor, a stator core, and a stator coil, and the rotor is connected to the output module; the controller is set as an MCU chip, the rotation speed detection module is integrated in the MCU chip, the MCU chip detects the back electromotive force of the stator coil, and the real-time rotation speed is determined through the zero-crossing time of the back electromotive force of the stator coil
Preferably, the motor is a brushless motor, the brushless motor includes a rotor, a stator core, and a stator coil, and the rotor is connected to the output module; the rotating speed detection module comprises a position sensor, the position sensor detects the position of the rotor and outputs a position signal of the rotor to the controller, and the controller determines the real-time rotating speed according to the position signal.
Preferably, the rectifying circuit is connected to the inverter circuit after passing through the smoothing filter circuit, the smoothing filter circuit is provided with a single capacitor or two or more capacitors connected in parallel, and the capacitors are electrolytic capacitors.
Preferably, the controller is electrically connected with a rotation speed setting module, the rotation speed setting module is provided with more than one preset rotation speed, and the rotation speed setting module outputs the preset rotation speed to the controller.
Preferably, the controller is electrically connected to a difference setting module, the difference setting module sets at least one preset difference, and the difference setting module outputs the preset difference to the controller.
Compared with the prior art, the utility model discloses following beneficial effect has: this controller of exchanging brushless electric tool passes through the real-time rotational speed that rotational speed detection module detected the motor, compares with predetermineeing the rotational speed, and according to the result of comparison, the controller passes through drive circuit control inverter circuit's duty cycle control motor's real-time rotational speed, makes the real-time rotational speed of motor is steady. With this arrangement, the voltage applied to the motor is controlled by detecting the time-varying rotation speed of the real motor without being affected by the input voltage, so that the motor can maintain a smooth output even if the ac power supply is a generator or a pulsating voltage with a large noise disturbance is applied.
[ description of the drawings ]
The following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings:
fig. 1 is a circuit diagram of a counter electromotive force detection circuit as a rotation speed detection module according to a first embodiment of the present invention.
Fig. 2 is a circuit diagram of the second embodiment of the present invention in which the rotation speed detection module is integrated in the MCU chip.
Fig. 3 is a circuit diagram of a rotation speed detecting module as a position sensor according to a third embodiment of the present invention.
Fig. 4 is a graph of duty ratio of the inverter circuit according to the real-time rotation speed control.
Fig. 5 is a schematic side view of an ac brushless electric power tool according to a first embodiment of the present invention.
Fig. 6 is a graph of controlling a duty ratio of an inverter circuit according to an input voltage in the related art.
The meaning of the reference symbols in the figures:
11. rectifier circuit 12, filter circuit 13, current detection circuit 21, drive circuit 22, three-phase bridge inverter circuit 23, counter electromotive force detection circuit 24, position sensor 3, three-phase brushless motor 31, stator coil Rs, current detection resistor 4, controller 41, voltage transformation module 42, MCU chip 43, rotation speed setting module 44, difference setting module R4R 5R 6, voltage division resistor R1R 2R 3, pull-up resistor VT1-VT6, switch tube UA UB UC, voltage comparator 51, and housing
[ detailed description of the invention ]
The first embodiment:
as shown in fig. 1, 4 and 5, an ac brushless electric tool according to a first embodiment of the present invention includes a housing 51, and a motor, a controller 4 and a driving module disposed inside the housing 51, wherein the motor is a three-phase brushless motor 3 in this preferred embodiment; the three-phase brushless motor 3 is connected with an output module, and the output module transmits the energy of the three-phase brushless motor 3 to an external load; the driving module is provided with a driving circuit 21 and an inverter circuit, the inverter circuit is a three-phase bridge inverter circuit 22 in the best embodiment, and the driving circuit 21 controls the duty ratio of the three-phase bridge inverter circuit 22; the controller 4 controls the operation of the three-phase brushless motor 3 through the driving module; the alternating current brushless electric tool is powered by an alternating current power supply, for example, the alternating current brushless electric tool is directly connected to commercial power, the alternating current power supply is electrically connected to the three-phase bridge inverter circuit 22 after passing through the rectification circuit 11, the three-phase bridge inverter circuit 22 is electrically connected to the three-phase brushless motor 3 to supply power to the three-phase brushless motor 3, the rectification circuit 11 is electrically connected to the transformation module 41, and the transformation module 41 converts the high-voltage direct current output by the rectification circuit 11 into low-voltage direct current to supply power to the controller 4; the three-phase brushless motor 3 electrically connected with rotational speed detection module, the rotational speed detection module detects the real-time rotational speed of three-phase brushless motor 3, will the real-time rotational speed convey to controller 4, the inside storage of controller 4 has the rotational speed of predetermineeing, controller 4 according to the relation of real-time rotational speed for predetermineeing the rotational speed, also be the real-time rotational speed with predetermine the difference of rotational speed, through drive circuit 21 control the duty cycle of three-phase bridge inverter circuit 22, the larger the duty cycle of three-phase bridge inverter circuit 22 the higher the real-time rotational speed. Further, the rectifying circuit 11 is connected to the three-phase bridge inverter circuit 22 after passing through the smoothing filter circuit 12, the smoothing filter circuit 12 is provided with a single capacitor or two or more capacitors connected in parallel, the capacitor is an electrolytic capacitor, the alternating current power supply is changed into direct current pulsating voltage after passing through the rectifying circuit 11, and then the direct current pulsating voltage is smoother through the smoothing filter circuit 12.
As shown in fig. 6, in the prior art, the controller 4 adjusts the duty ratio of the switching tube according to the rectified pulsating voltage to achieve the purpose of stabilizing the output of the motor, and the defect is that if the accessed ac power supply is a generator or a pulsating voltage with large noise interference, the controller 4 cannot accurately determine the current actual voltage, and the misdetermination of the controller 4 may cause an error in the on duty ratio, which results in unstable output of the motor and stalling of the tool. As shown in fig. 4, the controller 4 detects the real-time rotation speed of the three-phase brushless motor 3 through the rotation speed detection module, compares the real-time rotation speed with the preset rotation speed, and controls the duty ratio of the three-phase bridge inverter circuit 22 through the driving circuit 21 according to the difference between the real-time rotation speed and the preset rotation speed to control the real-time rotation speed of the three-phase brushless motor 3, so that the real-time rotation speed of the three-phase brushless motor 3 is more stable. With this arrangement, the output of the three-phase brushless motor 3 is not affected by the input voltage, and the three-phase brushless motor 3 can maintain a smooth output even when the ac power supply is a generator or a pulsating voltage with a large noise disturbance.
A preset difference value is stored in the controller 4; when the real-time rotating speed is lower than the preset rotating speed, the controller 4 controls the duty ratio of the three-phase bridge inverter circuit 22 to be increased to a value higher than the current duty ratio through the driving circuit 21, so that the absolute value of the difference between the real-time rotating speed of the three-phase brushless motor 3 and the preset rotating speed is not more than the preset difference, the real-time rotating speed is as close as possible to the preset rotating speed, and the three-phase brushless motor 3 keeps stable output; when the real-time rotating speed is greater than the preset rotating speed, the controller 4 controls the duty ratio of the three-phase bridge type inverter circuit 22 to be reduced to a value lower than the current duty ratio through the driving circuit 21, so that the absolute value of the difference between the real-time rotating speed of the three-phase brushless motor 3 and the preset rotating speed is not more than the preset difference, the real-time rotating speed is as close as possible to the preset rotating speed, and the three-phase brushless motor 3 keeps stable output. Further, the controller 4 is electrically connected to a difference setting module 44, the difference setting module 44 sets one or more preset differences, the difference setting module 44 outputs the preset differences to the controller 4, and a user can use the difference setting module 44 to set the preset differences by himself to freely control the output stability of the ac brushless electric tool. Controller 4 electric connection has rotational speed to set for module 43, rotational speed sets for module 43 and sets up more than one preset rotational speed, rotational speed sets for module 43 will preset the rotational speed and export to controller 4, the user can utilize rotational speed sets for module 43 sets for by oneself preset rotational speed, thereby reaches the messenger three-phase brushless motor 3 exports the purpose of multiple rotational speed.
Further, the bus of the three-phase bridge inverter circuit 22 is further provided with a current detection device, which in this preferred embodiment is a current detection resistor Rs, the current detection resistor Rs is electrically connected to the controller 4 through a current detection circuit 13, the controller 4 detects that the current flowing through the current detection resistor Rs is abnormal, for example, excessive, through the current detection circuit 13, and the controller 4 controls the three-phase brushless motor 3 through the driving module, for example, the three-phase brushless motor 3 stops operating.
As shown in fig. 1, the three-phase bridge inverter circuit 22 includes an upper bridge arm and a lower bridge arm, the upper bridge arm includes switching tubes VT1, VT3, VT5, and the lower bridge arm includes switching tubes VT2, VT4, VT 6; the rotating speed detection module comprises a counter electromotive force detection circuit 23, the counter electromotive force detection circuit 23 is provided with three voltage comparators UA, UB and UC, each voltage comparator UA, UB and UC comprises an input end anode, an input end cathode and an output end, the three voltage comparators UA, UB and UC are respectively connected to a direct current power supply through pull-up resistors R1, R2 and R3, and the direct current power supply is set to be +5V in the best embodiment; the three-phase brushless motor 3 comprises a rotor (not shown), a stator core (not shown) and a stator coil 31, the rotor is connected with the output module and is used for transmitting the energy of the motor to an external load, the stator coil 31 is respectively and electrically connected to the positive poles of the input ends of the three voltage comparators UA, UB and UC through voltage dividing resistors R4, R5 and R6, the negative poles of the input ends of the three voltage comparators UA, UB and UC are all grounded, the output ends of the three voltage comparators UA, UB and UC are electrically connected to the controller 4, when the three-phase brushless motor 3 is driven to operate, the switching tubes are sequentially conducted in pairs, so that the current flows through the two-phase stator coils 31, the positive pole of the input end of the voltage comparator detects the counter electromotive force of the stator coil 31 which is not connected with one phase, and compares the counter electromotive force with the voltage of the negative pole of the input end of the voltage, the output end of the voltage comparator transmits a comparison signal such as a high level signal or a low level signal to the controller 4, when the comparison signal of the voltage comparator changes from the high level signal to the low level signal or from the low level signal to the high level signal, the rotor is in a position opposite to the phase without switching on the stator coil 31, and the controller 4 judges the position of the rotor according to the position, and then calculates the real-time rotating speed of the three-phase brushless motor 3.
Second embodiment:
as shown in fig. 2, the second embodiment is different from the first embodiment in that the controller 4 is an MCU chip 42, the MCU chip 42 integrates the rotation speed detection module into itself, when the three-phase brushless motor 3 is driven to operate, the MCU chip 42 directly detects the back electromotive force of a phase of the stator coil 31 that is not connected, and when the back electromotive force is at a zero-crossing time, that is, when the electromotive force jumps from a positive electromotive force to a negative electromotive force or from a negative electromotive force to a positive electromotive force, the rotor is at a position facing the phase of the stator coil 31 that is not connected, and the controller 4 determines the position of the rotor based on the detected back electromotive force, and calculates the real-time rotation speed of the three-phase brushless motor 3.
The third embodiment:
as shown in fig. 3, the third embodiment is different from the first embodiment in that the rotation speed detection module includes a position sensor 24, such as a hall element, the position sensor 24 detects the position of the rotor, outputs a position signal of the rotor to the controller 4, and the controller 4 determines the position of the rotor based on the position signal, and calculates the real-time rotation speed of the three-phase brushless motor 3.
The present invention is not limited to the above-described embodiments. It will be readily appreciated by those skilled in the art that there are numerous alternatives to the ac brushless power tool of the present invention without departing from the spirit and scope of the invention. The protection scope of the present invention is subject to the content of the claims.
Claims (9)
1. An AC brushless electric tool comprises a shell, a motor, a controller and a driving module, wherein the motor, the controller and the driving module are arranged inside the shell; the motor is connected with an output module, and the output module transmits the energy of the motor to an external load; the driving module is provided with a driving circuit and an inverter circuit, and the driving circuit controls the duty ratio of the inverter circuit; the controller controls the operation of the motor through the driving module; the alternating current brushless electric tool is powered by an alternating current power supply, the alternating current power supply is electrically connected to the inverter circuit after passing through the rectifying circuit, the inverter circuit is electrically connected to the motor and supplies power to the motor, the rectifying circuit is electrically connected with the voltage transformation module, the voltage transformation module converts high-voltage direct current output by the rectifying circuit into low-voltage direct current to supply power to the controller, and the alternating current brushless electric tool is characterized in that: the motor is electrically connected with a rotating speed detection module, the rotating speed detection module detects the real-time rotating speed of the motor and transmits the real-time rotating speed to the controller, a preset rotating speed is stored in the controller, the controller controls the duty ratio of the inverter circuit through the driving circuit according to the difference value of the real-time rotating speed relative to the preset rotating speed, and the larger the duty ratio of the inverter circuit is, the higher the real-time rotating speed is.
2. The ac brushless electric power tool of claim 1, wherein: a preset difference value is stored in the controller; when the real-time rotating speed is lower than the preset rotating speed, the controller controls the duty ratio of the inverter circuit to be increased to a value higher than the current duty ratio through the driving circuit, so that the absolute value of the difference value between the real-time rotating speed of the motor and the preset rotating speed is not more than the preset difference value.
3. The ac brushless electric power tool of claim 1, wherein: a preset difference value is stored in the controller; when the real-time rotating speed is greater than the preset rotating speed, the controller controls the duty ratio of the inverter circuit to be reduced to a value lower than the current duty ratio through the driving circuit, so that the absolute value of the difference value between the real-time rotating speed of the motor and the preset rotating speed is not more than the preset difference value.
4. An ac brushless electric power tool as claimed in any one of claims 1 to 3, wherein: the rotating speed detection module comprises a back electromotive force detection circuit, and the back electromotive force detection circuit is provided with a voltage comparator; the motor is a brushless motor, the brushless motor comprises a rotor, a stator core and a stator coil, the rotor is connected with the output module, the stator coil is electrically connected to the positive pole of the input end of the voltage comparator through a divider resistor, the negative pole of the input end of the voltage comparator is grounded, the output end of the voltage comparator is electrically connected to the controller, the positive pole of the input end of the voltage comparator detects the back electromotive force of the stator coil and compares the back electromotive force with the negative pole voltage of the input end of the voltage comparator, the output end of the voltage comparator outputs a comparison signal to the controller, and the controller determines the real-time rotating speed according to the comparison signal.
5. An ac brushless electric power tool as claimed in any one of claims 1 to 3, wherein: the motor is a brushless motor, the brushless motor comprises a rotor, a stator core and a stator coil, and the rotor is connected with the output module; the controller is set as an MCU chip, the MCU chip integrates the rotating speed detection module in the MCU chip, the MCU chip detects the back electromotive force of the stator coil, and the real-time rotating speed is determined through the zero-crossing time of the back electromotive force of the stator coil.
6. An ac brushless electric power tool as claimed in any one of claims 1 to 3, wherein: the motor is a brushless motor, the brushless motor comprises a rotor, a stator core and a stator coil, and the rotor is connected with the output module; the rotating speed detection module comprises a position sensor, the position sensor detects the position of the rotor and outputs a position signal of the rotor to the controller, and the controller determines the real-time rotating speed according to the position signal.
7. An ac brushless electric power tool as claimed in any one of claims 1 to 3, wherein: the rectifying circuit is connected to the inverter circuit after passing through the smoothing filter circuit, the smoothing filter circuit is provided with a single capacitor or more than two capacitors connected in parallel, and the capacitors are electrolytic capacitors.
8. An ac brushless electric power tool as claimed in any one of claims 1 to 3, wherein: the controller electric connection has the rotational speed to set for the module, the rotational speed sets for the module and sets up more than one preset rotational speed, the rotational speed sets for the module will preset the rotational speed and export to the controller.
9. An ac brushless electric power tool as claimed in claim 2 or 3, wherein: the controller electric connection has difference setting module, difference setting module sets up more than one preset difference, difference setting module will preset the difference and export to the controller.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020926864.7U CN212210877U (en) | 2020-05-27 | 2020-05-27 | AC brushless electric tool |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020926864.7U CN212210877U (en) | 2020-05-27 | 2020-05-27 | AC brushless electric tool |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212210877U true CN212210877U (en) | 2020-12-22 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202020926864.7U Active CN212210877U (en) | 2020-05-27 | 2020-05-27 | AC brushless electric tool |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN212210877U (en) |
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2020
- 2020-05-27 CN CN202020926864.7U patent/CN212210877U/en active Active
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