CN210577798U - Power-on protection circuit and electric tool - Google Patents
Power-on protection circuit and electric tool Download PDFInfo
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- CN210577798U CN210577798U CN201921505545.2U CN201921505545U CN210577798U CN 210577798 U CN210577798 U CN 210577798U CN 201921505545 U CN201921505545 U CN 201921505545U CN 210577798 U CN210577798 U CN 210577798U
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Abstract
The utility model relates to an electric tool technical field provides an go up electric protection circuit and electric tool. Wherein, go up electric protection circuit and be applied to electric tool, electric tool includes starting switch and load, and starting switch includes first end and second end, and starting switch's first end is used for being connected with the access power, goes up electric protection circuit and includes: the power-on detection circuit is used for being connected with the access power supply to detect the power-on voltage of the access power supply; the switch detection circuit is connected with the second end of the starting switch and used for outputting a level signal according to the switching state of the starting switch, wherein when the starting switch is in a closed state, the switch detection circuit outputs a first level; and the control circuit is respectively connected with the power-on detection circuit, the switch detection circuit and the load and is used for cutting off the power-on loops at two ends of the load when the power-on voltage is less than the preset voltage and the level signal is at the first level. The embodiment of the utility model provides a promoted electric tool's security.
Description
[ technical field ] A method for producing a semiconductor device
The utility model relates to an electric tool technical field especially relates to an go up electric protection circuit and electric tool.
[ background of the invention ]
The electric tool comprises a starting switch and a load, and the starting process comprises two types: firstly, connecting an access power supply, pressing a starting switch, and starting a load; and secondly, the starting switch is pressed all the time, the power supply is connected and connected, and the load is started. However, in the second case, after the power supply is connected, the load is started instantly and operated quickly, which may cause some emergencies and potential safety hazards.
[ Utility model ] content
The utility model aims at providing an go up electric protection circuit and electric tool can avoid electric tool to go up and press starting switch always before, and after connecting the access power, the load starts and fast run in the twinkling of an eye, probably causes some emergency, has the problem of potential safety hazard to, promoted electric tool's security.
In order to solve the above technical problem, an embodiment of the present invention provides the following technical solution:
the embodiment of the utility model provides a go up electric protection circuit is applied to electric tool, electric tool includes starting switch and load, starting switch includes first end and second end, starting switch's first end is used for being connected with the access power, go up electric protection circuit and include:
the power-on detection circuit is connected with the access power supply to detect the power-on voltage of the access power supply;
the switch detection circuit is connected with the second end of the starting switch and used for outputting a level signal according to the switching state of the starting switch, wherein when the starting switch is in a closed state, the switch detection circuit outputs a first level;
and the control circuit is respectively connected with the power-on detection circuit, the switch detection circuit and the load and is used for cutting off the power-on loops at two ends of the load when the power-on voltage is less than a preset voltage and the level signal is at the first level.
Optionally, the power-up detection circuit includes:
the charging circuit is used for charging when the access power supply is powered on;
the first voltage division circuit is respectively connected with the access power supply and the charging circuit and is used for sampling electrifying voltages at two ends of the charging circuit;
and the first current limiting circuit is respectively connected with the voltage dividing circuit, the charging circuit and the control circuit and is used for transmitting an electric signal obtained after the current limiting processing is carried out on the electrifying voltage to the control circuit.
Optionally, the charging circuit includes a capacitor, the first voltage dividing circuit includes a first resistor and a second resistor, and the first current limiting circuit includes a third resistor;
one end of the capacitor is connected with one end of the first resistor, one end of the second resistor and one end of the third resistor, and the other end of the capacitor is grounded;
the other end of the first resistor is used for being connected with the access power supply;
the other end of the second resistor is grounded;
the other end of the third resistor is connected with the first input end of the control circuit.
The switch detection circuit includes:
the second voltage division circuit is connected with the second end of the starting switch and used for outputting a level signal according to the switching state of the starting switch;
and the second current limiting circuit is respectively connected with the second voltage division circuit and the control circuit and is used for transmitting the electric signal subjected to current limiting processing on the level signal to the control circuit.
Optionally, the second voltage dividing circuit includes a fourth resistor and a fifth resistor, and the second current limiting circuit includes a sixth resistor;
one end of the fourth resistor is connected with the second end of the starting switch, and the other end of the fourth resistor is connected with one end of the fifth resistor and one end of the sixth resistor;
the other end of the fifth resistor is grounded;
the other end of the sixth resistor is connected with the second input end of the control circuit.
The control circuit includes:
the controller is respectively connected with the power-on detection circuit and the switch detection circuit and used for receiving the power-on voltage and the level signal and outputting a control signal according to the power-on voltage and the level signal, wherein when the power-on voltage is less than a preset voltage and the level signal is at the first level, the control signal is at a second level;
and the protection circuit is respectively connected with the controller and the load and used for cutting off the power-on loops at two ends of the load when the control signal is at the second level.
Optionally, the protection circuit comprises:
the switch circuit is connected with the second end of the starting switch and is also connected in series with the power-on loops at two ends of the load;
and the switch driving circuit is respectively connected with the controller and the switch circuit and is used for controlling the switch state of the switch circuit according to the control signal sent by the controller, wherein when the control signal is at the second level, the switch driving circuit controls the switch circuit to be switched off so as to cut off the power-on loops at the two ends of the load.
Optionally, the switch driving circuit includes a seventh resistor, an eighth resistor, and an NPN transistor, and the switch circuit includes a ninth resistor and a thyristor;
one end of the seventh resistor is connected with the output end of the controller, and the other end of the seventh resistor is connected with one end of the eighth resistor and the base electrode of the NPN triode;
the other end of the eighth resistor is grounded with an emitting electrode of the NPN triode;
a collector of the NPN triode is connected with one end of the ninth resistor;
the other end of the ninth resistor is connected with a control electrode of the controlled silicon;
the anode of the controllable silicon is connected with the second end of the starting switch, and the cathode of the controllable silicon is connected with the load.
Optionally, the switch driving circuit includes a tenth resistor, and the switch circuit includes an NMOS transistor;
one end of the tenth resistor is connected with the output end of the controller, and the other end of the tenth resistor is connected with the grid electrode of the NMOS tube;
the drain electrode of the NMOS tube is connected with the load, and the source electrode of the NMOS tube is grounded.
The embodiment of the utility model provides an electric tool is still provided, include.
The starting switch comprises a first end and a second end, and the first end is used for being connected with an access power supply;
the motor is connected with the second end of the starting switch; and the number of the first and second groups,
the power-on protection circuit of any one of the above embodiments is connected to the second end of the start switch, the access power supply, and the motor, respectively.
The utility model has the advantages that: compared with the prior art, the embodiment of the utility model provides an go up electric protection circuit and electric tool. The power-on detection circuit detects power-on voltage accessed to a power supply, the switch detection circuit outputs a level signal according to the switch state of the starting switch, when the starting switch is in a closed state, the switch detection circuit outputs a first level, and the control circuit is used for cutting off power-on loops at two ends of a load when the power-on voltage is smaller than a preset voltage and the level signal is the first level. Consequently, press the starting switch always at the user and reconnect the condition of inserting the power, at this moment, the starting switch is in the closure state, switch detection circuitry exports first level, go up the last electric voltage that electric detection circuitry detected the access power, go up the electric voltage and increase along with the time increase of connecting the access power, in the time of the utmost point weak point, it is less than preset voltage to go up electric voltage, it is first level to satisfy simultaneously that last electric voltage is less than preset voltage and the level signal of switch detection circuitry output, control circuit cuts off the circular telegram return circuit at load both ends, the load can't start, thereby, the embodiment of the utility model provides a safety of electric tool has been promoted.
[ description of the drawings ]
One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.
Fig. 1 is a schematic structural diagram of an electric tool according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a structure of an upper power protection circuit and connection between the upper power protection circuit and an access power supply, a start switch, and a load according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a structure of a power-on detection circuit and a connection between the power-on detection circuit and an access power supply and a control circuit according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a structure of a switch detection circuit and a connection between the switch detection circuit and a start switch and a control circuit according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a structure of a control circuit and connections thereof with a first current limiting circuit, a second current limiting circuit, a start switch, and a load according to an embodiment of the present invention;
fig. 6 is a schematic circuit connection diagram of an electrifying detection circuit according to an embodiment of the present invention;
fig. 7 is a schematic circuit connection diagram of another power-on detection circuit according to an embodiment of the present invention;
fig. 8 is a schematic diagram of a curve for charging the capacitor C1 according to an embodiment of the present invention.
[ detailed description ] embodiments
To facilitate an understanding of the present application, the present application is described in more detail below with reference to the accompanying drawings and detailed description. It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may be present. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In addition, the technical features mentioned in the different embodiments of the present application described below may be combined with each other as long as they do not conflict with each other.
Fig. 1 is a schematic structural diagram of an electric tool according to an embodiment of the present invention. As shown in fig. 1, the power tool 200 includes a start switch 21, a motor 22, and a power-on protection circuit 100.
Among the common electric tools 200 are electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, electric impact drills, concrete vibrators, electric planers, and the like. The electric tools 200 include wired electric tools and cordless electric tools, classified by the type of power cord; the power tool 200 includes a direct current power tool and an alternating current power tool, which are classified by types of direct current and alternating current, wherein the cordless power tool generally employs a direct current type.
In this embodiment, when the electric power tool 200 is powered on and operated, the electric power tool needs to be connected to an access power source 210, and the access power source 210 is configured to provide a power voltage for the electric power tool 200. When the electric tool 200 is a wired electric tool, the access power supply 210 includes commercial power, and at this time, the electric tool 200 includes a power cord having a plug through which the electric tool 200 is accessed to the commercial power; when the electric tool 200 is a wireless electric tool, the access power supply 210 includes built-in energy storage power supplies such as dry batteries, lead-acid storage batteries, nickel-cadmium batteries, nickel-hydrogen batteries, lithium batteries, and preferably, the access power supply 210 adopts a lithium battery pack, and the lithium battery pack provides power supply voltage for the electric tool 200 through installation.
The start switch 21 includes a first end 21a and a second end 21b, and the first end 21a is used for connecting with the access power supply 210.
The starting switch 21 mainly comprises six types of switches including a speed regulator, a trigger switch, a ship-shaped switch, a single-speed switch, a transverse power soft starting switch and a large-current microswitch. Generally, the start switch 21 is disposed at a holding portion of the electric power tool 200, and a part of the start switch protrudes from a housing of the electric power tool 200, so that when a human hand holds the electric power tool 200, the start switch 21 can be pulled or pressed by fingers to control the on/off of a load motor of the electric power tool 200, and when the electric power tool 200 is an electronic speed-adjusting electric power tool, the pressing depth of the start switch 21 can be controlled by fingers to adjust the rotation speed of the load motor of the electric power tool 200.
The motor 22 is connected to the second end 21b of the start switch 21.
The motor 22 is a load of the electric tool 200, and mainly functions to generate a driving torque, and as a power source of the electric tool 200, the motor drives a drill, a screwdriver, a plane, and the like of the electric tool 200, and the drill, the screwdriver, and the plane have a very high risk in a high-speed rotation situation, and if the electric tool 200 is powered on, the user presses the start switch 21 all the time, and after the power supply is connected, the motor 22 is started instantly to drive the drill, the screwdriver, the plane, and the like to rotate at a high speed, which may cause a risk that the user cannot reach by accident.
The power-on protection circuit 100 is respectively connected to the second end 21b of the start switch 21, the access power source 210 and the motor 22. The power-on protection circuit 100 may cut off the power-on loop of the motor when the power tool is powered on and the switch is turned on, so as to prevent the motor from rotating.
To sum up, the embodiment of the utility model provides an electric tool is connected last electric protection circuit through the second end with starting switch, access power and motor respectively, avoids electric tool to press starting switch before going up always, and after connecting the access power, the load starts in the twinkling of an eye and fast run, probably causes some emergency, has the problem of potential safety hazard to, electric tool's security has been promoted.
Referring to fig. 2, the power-on protection circuit 100 is applied to a power tool 200, the power tool 200 includes a start switch 21 and a load 22, the start switch 21 includes a first end 21a and a second end 21b, the first end 21a of the start switch 21 is used for connecting with a power source 210, and the power-on protection circuit 100 includes a power-on detection circuit 10, a switch detection circuit 20 and a control circuit 30.
The structures and functions of the power-on detection circuit 10, the switch detection circuit 20, and the control circuit 30 are described below, respectively.
The power-on detection circuit 10 is configured to be connected to the access power source 210 to detect a power-on voltage of the access power source 210.
Referring to fig. 3, the power-up detection circuit 10 includes a charging circuit 101, a first voltage divider circuit 102, and a first current limiting circuit 103.
The charging circuit 101 is configured to charge when the access power supply 210 is powered on; the first voltage dividing circuit 102 is respectively connected to the access power supply 210 and the charging circuit 101, and is configured to sample power-on voltages at two ends of the charging circuit 101; the first current limiting circuit 103 is connected to the voltage dividing circuit 102, the charging circuit 101, and the control circuit 30, and is configured to transmit an electrical signal obtained by performing current limiting processing on the power-on voltage to the control circuit 30.
Specifically, referring to fig. 6 or fig. 7, the charging circuit 101 includes a capacitor C1, the first voltage divider circuit 102 includes a first resistor R1 and a second resistor R2, and the first current limiting circuit 103 includes a third resistor R3.
Specifically, one end of the capacitor C1 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, and the other end of the capacitor C1 is grounded; the other end of the first resistor R1 is used for being connected with the access power supply 210; the other end of the second resistor R2 is grounded; the other end of the third resistor R3 is connected to the first input terminal 301a of the control circuit 30.
The switch detection circuit 20 is connected to the second end 21b of the start switch 21, and configured to output a level signal according to a switching state of the start switch 21, where when the start switch 21 is in a closed state, the switch detection circuit 20 outputs a first level.
Referring to fig. 4, the switch detection circuit 20 includes a second voltage divider 201 and a second current limiting circuit 202.
The second voltage dividing circuit 201 is connected to the second end 21b of the start switch 21, and is configured to output a level signal according to a switching state of the start switch 21; the second current limiting circuit 202 is connected to the second voltage dividing circuit 201 and the control circuit 30, and is configured to transmit an electrical signal obtained by performing current limiting processing on the level signal to the control circuit 30.
Specifically, referring to fig. 6 or fig. 7, the second voltage divider 201 includes a fourth resistor R4 and a fifth resistor R5, and the second current limiting circuit 202 includes a sixth resistor R6.
Specifically, one end of the fourth resistor R4 is connected to the second end 21b of the start switch 21, and the other end of the fourth resistor R4 is connected to one end of the fifth resistor R5 and one end of the sixth resistor R6; the other end of the fifth resistor R5 is grounded; the other end of the sixth resistor R6 is connected to the second input terminal 301b of the control circuit 30.
The control circuit 30 is connected to the power-on detection circuit 10, the switch detection circuit 20, and the load 22, and is configured to cut off power-on loops at two ends of the load 22 when the power-on voltage is less than a preset voltage and the level signal is the first level.
In this embodiment, the first level signal is a high level signal.
Referring to fig. 5, the control circuit 30 includes a controller 301 and a protection circuit 302.
The controller 301 is connected to the first current limiting circuit 103 and the second current limiting circuit 202, and configured to receive the power-on voltage and the level signal, and output a control signal according to the power-on voltage and the level signal, where the control signal is at a second level when the power-on voltage is less than a preset voltage and the level signal is at the first level.
In this embodiment, the controller 301 includes a single chip microcomputer U1 and its peripheral circuits (not shown), and the single chip microcomputer U1 may adopt 51 series, Arduino series, STM32 series, and the like.
In some embodiments, the controller 301 may also be a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), an ARM (AcornRISC Machine) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination of these components; but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine; or as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The protection circuit 302 is respectively connected to the controller 301 and the load 22, and is configured to cut off the power-on loop at both ends of the load 22 when the control signal is at the second level.
The protection circuit 302 includes a switch circuit 3021 and a switch driver circuit 3022.
The switch circuit 3021 is connected to the second end 21b of the start switch 21, and the switch circuit 3021 is also connected in series to a power-on loop across the load 22; the switch driving circuit 3022 is respectively connected to the controller 301 and the switch circuit 3021, and is configured to control a switching state of the switch circuit 3021 according to the control signal sent by the controller 301, wherein when the control signal is at the second level, the switch driving circuit 3022 controls the switch circuit 3021 to be turned off to cut off the power-on loop across the load 22.
As shown in fig. 6, the switch driving circuit 3022 includes a seventh resistor R7, an eighth resistor R8, and an NPN transistor Q1, and the switch circuit 3021 includes a ninth resistor R9 and a thyristor D1.
One end of the seventh resistor R7 is connected to the output terminal 301c of the controller 301, and the other end of the seventh resistor R7 is connected to one end of the eighth resistor R8 and the base of the NPN transistor Q1; the other end of the eighth resistor R8 is grounded with the emitter of the NPN triode Q1; a collector of the NPN transistor Q1 is connected to one end of the ninth resistor R9; the other end of the ninth resistor R9 is connected with the control electrode of the controllable silicon D1; the anode of the thyristor D1 is connected to the second terminal 21b of the start switch 21, and the cathode of the thyristor D1 is connected to the load 22 (motor M1).
Correspondingly, a first end of the motor M1 is connected with a cathode of the thyristor D1, a second end of the motor M1 is grounded, and the switch circuit 3021 is connected in series with the power-on loops at two ends of the motor M1.
In summary, the operation of the power-on protection circuit 100 shown in fig. 6 is as follows:
when the user does not press the start switch 21 while the power tool 200 is connected to the power supply 210, the switch S1 (start switch 21) is in the off state.
As shown in fig. 8, when the electric tool 200 is connected to the access power supply 210, the single-chip microcomputer U1 completes initialization quickly, the power-on detection circuit 10 starts to operate, the output voltage VCC of the access power supply 210 charges the capacitor C1 through the first resistor R1, the voltage across the capacitor C1 increases with the increase of the charging time, the voltage across the capacitor C1 increases from 0V to V1 after the T1 time, and the voltage across the capacitor C1 is the voltage V1 after the capacitor C1 is fully charged.
The first voltage divider circuit 102 is composed of a first resistor R1 and a second resistor R2, the voltage V1 is determined by resistance values of the first resistor R1 and the second resistor R2, and the voltage signal at two ends of the capacitor C1 sampled by the first voltage divider circuit 102 is transmitted to the first input end 301a of the single chip microcomputer U1 through a third resistor R3. The power-on voltage of the access power supply 210 is detected by dividing the access power supply 210 by the first resistor R1 and the second resistor R2, and at this time, the power-on voltage of the access power supply 210 is equal to a voltage V1, wherein the voltage V1 is greater than the voltage V0, and the voltage V0 is a preset voltage.
When the electric tool 200 is connected to the power supply 210, the switch S1 is in an off state, the switch S1 is not connected to VCC, the second input end 301b of the single chip microcomputer U1 is pulled down to a low level by the fifth resistor R5 through the sixth resistor R6, the output end 301c of the single chip microcomputer U1 outputs a low level signal, the low level signal reaches the base of the NPN triode Q1 through the divided voltage of the seventh resistor R7 and the eighth resistor R8, the on condition of the NPN triode Q1 is not met, the NPN triode Q1 is turned off, at this time, the anode of the thyristor D1 has no forward voltage, the control electrode of the thyristor D1 has no trigger current, the thyristor D1 is turned off, the energization loops at two ends of the motor M1 are cut off, and the motor M1 does not work.
After a period of time T (T > T0), the user presses the switch S1, the switch S1 is in a closed state, the switch S1 is communicated with VCC, the fourth resistor R4 and the fifth resistor R5 form the second voltage division circuit 201, the second voltage division circuit 201 divides the voltage of VCC, and the acquired high-level signal is input to the second input terminal 301b of the single chip microcomputer U2 through the sixth resistor R6, that is, when the switch S1 is in the closed state, the level signal output by the switch detection circuit 20 is the high-level signal. When the first input end 301a of the single chip microcomputer U1 detects that the power-on voltage of the access power supply 210 is greater than the preset voltage V0 and the second input end 301b of the single chip microcomputer U1 detects that the level signal output by the switch detection circuit 20 is a high level signal, the output end 301c of the single chip microcomputer U1 outputs a high level signal, the high level signal reaches the base of the NPN triode Q1 through the divided voltage of the seventh resistor R7 and the eighth resistor R8, the conduction condition of the NPN triode Q1 is met, the NPN triode Q1 is turned on, at this time, the anode of the thyristor D1 has a forward voltage, the control electrode of the thyristor D1 has a trigger current, the thyristor D1 is turned on, the power-on loops at the two ends of the motor M1 are turned on, and the motor M1 starts.
It should be noted that the time T0 corresponding to the preset voltage V0 is very short, generally several tens of milliseconds, and the time for the user to press the switch S1 is much longer than several tens of milliseconds, so that when the user presses the switch S1, the power-on voltage of the access power supply 210 detected by the first input terminal 301a of the single chip microcomputer U1 is greater than the preset voltage V0.
When the user presses the start switch 21 all the time to connect the access power supply 210, the switch S1 is closed.
As shown in fig. 8, when the power tool 200 is connected to the access power supply 210, the single-chip microcomputer U1 completes initialization quickly, the power-on detection circuit 10 starts to operate, the output voltage VCC of the access power supply 210 charges the capacitor C1 through the first resistor R1, the voltage across the capacitor C1 increases with the increase of the charging time, and the voltage across the capacitor C1 increases from 0V to V after the time T (T < T0) elapses.
The first resistor R1 and the second resistor R2 form a first voltage divider circuit 102, and the first voltage divider circuit 102 samples voltage signals at two ends of the capacitor C1 and transmits the voltage signals to the first input end 301a of the single chip microcomputer U1 through the third resistor R3. The power-on voltage of the power supply 210 is detected through the power-on voltage at the two ends of the capacitor C1, and at this time, the power-on voltage of the power supply 210 is equal to the voltage V, wherein the voltage V0 is a preset voltage, and the voltage V is less than the voltage V0.
After the electric tool 200 is connected to the power supply 210, since the switch S1 is always in the closed state, the switch S1 is connected to VCC, the fourth resistor R4 and the fifth resistor R5 form the second voltage divider 201, the second voltage divider 201 divides the voltage of VCC, and the acquired high level signal is input to the second input terminal 301b of the single chip microcomputer U2 through the sixth resistor R6, that is, when the switch S1 is in the closed state, the level signal output by the switch detection circuit 20 is the high level signal.
After a period of time T (T < T0), when the first input end 301a of the single chip microcomputer U1 detects that the power-on voltage of the power supply 210 is lower than the preset voltage V0 and the second input end 301b of the single chip microcomputer U1 detects that the level signal output by the switch detection circuit 20 is a high level signal, the output end 301c of the single chip microcomputer U1 outputs a low level signal, the low level signal reaches the base of the NPN triode Q1 through the voltage division of the seventh resistor R7 and the eighth resistor R8, the conduction condition of the NPN triode Q1 is not met, the NPN triode Q1 is turned off, at this time, the anode of the thyristor D1 has no forward voltage, the control electrode of the thyristor D1 has no trigger current, the thyristor D1 is turned off, the energization loops at the two ends of the motor M1 are cut off, and the motor M1. Therefore, when the user presses the start switch 21 all the time and connects to the power supply 210, the power tool 200 starts the power-on protection mechanism in a short time, the motor M1 of the power tool 200 does not operate, and the safety of the power tool 200 is improved.
In some optional embodiments of this embodiment, as shown in fig. 7, the switch driving circuit 3022 includes a tenth resistor R10, and the switch circuit 3021 includes an NMOS transistor Q2.
One end of the tenth resistor R10 is connected to the output terminal 301c of the controller 301, and the other end of the tenth resistor R10 is connected to the gate of the NMOS transistor Q2; the drain electrode of the NMOS tube Q2 is connected with the load 22, and the source electrode of the NMOS tube is grounded.
Correspondingly, a first end of the motor M1 is connected to the second end 21b of the start switch 21, a second end of the motor M1 is connected to the drain of the NMOS transistor Q2, and the switch circuit 3021 is connected in series to the current-carrying loop at both ends of the motor M1.
In summary, the operation of the power-on protection circuit 100 shown in fig. 7 is as follows:
when the user does not press the start switch 21 while the power tool 200 is connected to the power supply 210, the switch S1 is in the off state.
As shown in fig. 8, when the electric tool 200 is connected to the access power supply 210, the single-chip microcomputer U1 completes initialization quickly, the power-on detection circuit 10 starts to operate, the output voltage VCC of the access power supply 210 charges the capacitor C1 through the first resistor R1, the voltage across the capacitor C1 increases with the increase of the charging time, the voltage across the capacitor C1 increases from 0V to V1 after the T1 time, and the voltage across the capacitor C1 is the voltage V1 after the capacitor C1 is fully charged.
The first voltage divider circuit 102 is composed of a first resistor R1 and a second resistor R2, the voltage V1 is determined by resistance values of the first resistor R1 and the second resistor R2, and the voltage signal at two ends of the capacitor C1 sampled by the first voltage divider circuit 102 is transmitted to the first input end 301a of the single chip microcomputer U1 through a third resistor R3. The power-on voltage of the access power supply 210 is detected by dividing the access power supply 210 by the first resistor R1 and the second resistor R2, and at this time, the power-on voltage of the access power supply 210 is equal to a voltage V1, wherein the voltage V1 is greater than the voltage V0, and the voltage V0 is a preset voltage.
After the electric tool 200 is connected to the power supply 210, the switch S1 is in an off state, the switch S1 is not connected to the VCC, the second input end 301b of the single chip microcomputer U1 is pulled down to a low level by the fifth resistor R5 through the sixth resistor R6, the output end 301c of the single chip microcomputer U1 outputs a low level signal, the low level signal reaches the gate of the NMOS transistor Q2 through the tenth resistor R10, the on condition of the NMOS transistor Q2 is not met, the NMOS transistor Q2 is turned off, the power-on loops at two ends of the motor M1 are cut off, and the motor M1 does not work.
After a period of time T (T > T0), the user presses the switch S1, the switch S1 is in a closed state, the switch S1 is communicated with VCC, the fourth resistor R4 and the fifth resistor R5 form the second voltage division circuit 201, the second voltage division circuit 201 divides the voltage of VCC, and the acquired high-level signal is input to the second input terminal 301b of the single chip microcomputer U2 through the sixth resistor R6, that is, when the switch S1 is in the closed state, the level signal output by the switch detection circuit 20 is the high-level signal.
When the first input end 301a of the single chip microcomputer U1 detects that the power-on voltage of the access power supply 210 is greater than the preset voltage V0 and the second input end 301b of the single chip microcomputer U1 detects that the level signal output by the switch detection circuit 20 is a high level signal, the output end 301c of the single chip microcomputer U1 outputs a high level signal, the high level signal reaches the gate of the NMOS transistor Q2 through the tenth resistor R10, the conduction condition of the NMOS transistor Q2 is met, the NMOS transistor Q2 is conducted, the conduction loops at two ends of the motor M1 are conducted, and the motor M1 starts to operate.
When the user presses the start switch 21 all the time to connect the access power supply 210, the switch S1 is closed.
As shown in fig. 8, when the power tool 200 is connected to the access power supply 210, the single-chip microcomputer U1 completes initialization quickly, the power-on detection circuit 10 starts to operate, the output voltage VCC of the access power supply 210 charges the capacitor C1 through the first resistor R1, the voltage across the capacitor C1 increases with the increase of the charging time, and the voltage across the capacitor C1 increases from 0V to V after the time T (T < T0) elapses.
The first voltage divider circuit 102 is composed of a first resistor R1 and a second resistor R2, the first voltage divider circuit 102 samples voltage signals at two ends of a capacitor C1, the voltage signals are transmitted to a first input end 301a of a single chip microcomputer U1 through a third resistor R3, the power-on voltage of the power supply 210 can be detected through the power-on voltage at two ends of the capacitor C1, at the moment, the power-on voltage of the power supply 210 is equal to a voltage V, wherein the voltage V0 is a preset voltage, and the voltage V is smaller than the voltage V0.
After the electric tool 200 is connected to the power supply 210, since the switch S1 is always in the closed state, the switch S1 is connected to VCC, the fourth resistor R4 and the fifth resistor R5 form the second voltage divider 201, the second voltage divider 201 divides the voltage of VCC, and the acquired high level signal is input to the second input terminal 301b of the single chip microcomputer U2 through the sixth resistor R6, that is, when the switch S1 is in the closed state, the level signal output by the switch detection circuit 20 is the high level signal.
After a period of time T (T < T0), when the first input end 301a of the single chip microcomputer U1 detects that the power-on voltage of the access power supply 210 is less than the preset voltage V0 and the second input end 301b of the single chip microcomputer U1 detects that the level signal output by the switch detection circuit 20 is a high level signal, the output end 301c of the single chip microcomputer U1 outputs a low level signal, the low level signal reaches the gate of the NMOS transistor Q2 through the tenth resistor R10, the conduction condition of the NMOS transistor Q2 is not met, the NMOS transistor Q2 is turned off, the power-on loops at the two ends of the motor M1 are cut off, and the motor M1 does not work. Therefore, when the user presses the start switch 21 all the time and connects to the power supply 210, the power tool 200 starts the power-on protection mechanism in a short time, the motor M1 of the power tool 200 does not operate, and the safety of the power tool 200 is improved.
The embodiment of the utility model provides a go up electric protection circuit detects the last electric voltage that inserts the power through last electric detection circuitry, and switch detection circuitry is according to starting switch's on-off state, output level signal, and control circuit is used for when last electric voltage is less than when predetermineeing voltage and level signal and be first level, cuts off the circular telegram return circuit at load both ends, consequently, the embodiment of the utility model provides a safety of electric tool has been promoted.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments can be combined, steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.
Claims (10)
1. A power-on protection circuit is applied to a power tool, the power tool comprises a starting switch and a load, the starting switch comprises a first end and a second end, the first end of the starting switch is used for being connected with an access power supply, and the power-on protection circuit comprises:
the power-on detection circuit is connected with the access power supply to detect the power-on voltage of the access power supply;
the switch detection circuit is connected with the second end of the starting switch and used for outputting a level signal according to the switching state of the starting switch, wherein when the starting switch is in a closed state, the switch detection circuit outputs a first level;
and the control circuit is respectively connected with the power-on detection circuit, the switch detection circuit and the load and is used for cutting off the power-on loops at two ends of the load when the power-on voltage is less than a preset voltage and the level signal is at the first level.
2. The power-on protection circuit of claim 1, wherein the power-on detection circuit comprises:
the charging circuit is used for charging when the access power supply is powered on;
the first voltage division circuit is respectively connected with the access power supply and the charging circuit and is used for sampling electrifying voltages at two ends of the charging circuit;
and the first current limiting circuit is respectively connected with the voltage dividing circuit, the charging circuit and the control circuit and is used for transmitting an electric signal obtained after the current limiting processing is carried out on the electrifying voltage to the control circuit.
3. The power-on protection circuit according to claim 2, wherein the charging circuit comprises a capacitor, the first voltage dividing circuit comprises a first resistor and a second resistor, and the first current limiting circuit comprises a third resistor;
one end of the capacitor is connected with one end of the first resistor, one end of the second resistor and one end of the third resistor, and the other end of the capacitor is grounded;
the other end of the first resistor is used for being connected with the access power supply;
the other end of the second resistor is grounded;
the other end of the third resistor is connected with the first input end of the control circuit.
4. The power-on protection circuit of claim 1, wherein the switch detection circuit comprises:
the second voltage division circuit is connected with the second end of the starting switch and used for outputting a level signal according to the switching state of the starting switch;
and the second current limiting circuit is respectively connected with the second voltage division circuit and the control circuit and is used for transmitting the electric signal subjected to current limiting processing on the level signal to the control circuit.
5. The power-on protection circuit according to claim 4, wherein the second voltage divider circuit includes a fourth resistor and a fifth resistor, and the second current limiting circuit includes a sixth resistor;
one end of the fourth resistor is connected with the second end of the starting switch, and the other end of the fourth resistor is connected with one end of the fifth resistor and one end of the sixth resistor;
the other end of the fifth resistor is grounded;
the other end of the sixth resistor is connected with the second input end of the control circuit.
6. The power-on protection circuit of claim 1, wherein the control circuit comprises:
the controller is respectively connected with the power-on detection circuit and the switch detection circuit and used for receiving the power-on voltage and the level signal and outputting a control signal according to the power-on voltage and the level signal, wherein when the power-on voltage is less than a preset voltage and the level signal is at the first level, the control signal is at a second level;
and the protection circuit is respectively connected with the controller and the load and used for cutting off the power-on loops at two ends of the load when the control signal is at the second level.
7. The power-on protection circuit of claim 6, wherein the protection circuit comprises:
the switch circuit is connected with the second end of the starting switch and is also connected in series with the power-on loops at two ends of the load;
and the switch driving circuit is respectively connected with the controller and the switch circuit and is used for controlling the switch state of the switch circuit according to the control signal sent by the controller, wherein when the control signal is at the second level, the switch driving circuit controls the switch circuit to be switched off so as to cut off the power-on loops at the two ends of the load.
8. The power-on protection circuit according to claim 7, wherein the switch driving circuit comprises a seventh resistor, an eighth resistor and an NPN transistor, and the switch circuit comprises a ninth resistor and a thyristor;
one end of the seventh resistor is connected with the output end of the controller, and the other end of the seventh resistor is connected with one end of the eighth resistor and the base electrode of the NPN triode;
the other end of the eighth resistor is grounded with an emitting electrode of the NPN triode;
a collector of the NPN triode is connected with one end of the ninth resistor;
the other end of the ninth resistor is connected with a control electrode of the controlled silicon;
the anode of the controllable silicon is connected with the second end of the starting switch, and the cathode of the controllable silicon is connected with the load.
9. The power-on protection circuit according to claim 7, wherein the switch driving circuit comprises a tenth resistor, and the switch circuit comprises an NMOS transistor;
one end of the tenth resistor is connected with the output end of the controller, and the other end of the tenth resistor is connected with the grid electrode of the NMOS tube;
the drain electrode of the NMOS tube is connected with the load, and the source electrode of the NMOS tube is grounded.
10. An electric power tool, characterized by comprising:
the starting switch comprises a first end and a second end, and the first end is used for being connected with an access power supply;
the motor is connected with the second end of the starting switch; and the number of the first and second groups,
the power-on protection circuit according to any one of claims 1 to 9, connected to the second terminal of the start switch, the access power source and the motor, respectively.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921505545.2U CN210577798U (en) | 2019-09-10 | 2019-09-10 | Power-on protection circuit and electric tool |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921505545.2U CN210577798U (en) | 2019-09-10 | 2019-09-10 | Power-on protection circuit and electric tool |
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| CN210577798U true CN210577798U (en) | 2020-05-19 |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112952759A (en) * | 2021-02-05 | 2021-06-11 | 格力博(江苏)股份有限公司 | Power-on protection circuit and electric tool |
| CN113676168A (en) * | 2021-07-15 | 2021-11-19 | 深圳拓邦股份有限公司 | Accidental start prevention circuit and electric appliance after power restoration |
| CN115395496A (en) * | 2022-09-06 | 2022-11-25 | 杭州七锐科技有限公司 | Starting safety protection circuit of hard switch electric tool |
| CN115800235A (en) * | 2021-09-09 | 2023-03-14 | 南京泉峰科技有限公司 | Starting protection circuit applied to electric tool and electric tool |
-
2019
- 2019-09-10 CN CN201921505545.2U patent/CN210577798U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112952759A (en) * | 2021-02-05 | 2021-06-11 | 格力博(江苏)股份有限公司 | Power-on protection circuit and electric tool |
| CN113676168A (en) * | 2021-07-15 | 2021-11-19 | 深圳拓邦股份有限公司 | Accidental start prevention circuit and electric appliance after power restoration |
| CN115800235A (en) * | 2021-09-09 | 2023-03-14 | 南京泉峰科技有限公司 | Starting protection circuit applied to electric tool and electric tool |
| CN115395496A (en) * | 2022-09-06 | 2022-11-25 | 杭州七锐科技有限公司 | Starting safety protection circuit of hard switch electric tool |
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