CN220732622U - Brushless motor control system and electric tool - Google Patents

Abstract

The utility model discloses a brushless motor control system and an electric tool, which comprise a main control unit, a PFC control unit, a motor driving unit, a brushless motor, a start-stop switch and a power supply unit, wherein the PFC unit is respectively and electrically connected with the PFC control unit, the motor driving unit and the power supply unit, and the motor driving unit is electrically connected with the brushless motor; the power supply unit comprises an AC/DC conversion module and a DC/DC conversion module which are electrically connected, and the braking unit is respectively and electrically connected with the DC/DC conversion module and the main control unit. The PFC unit synchronizes the voltage phase and the current phase, improves the power utilization rate, reduces reactive power loss, and stably and reliably controls the working state of the brushless motor through the motor driving unit. When the main control unit detects that the start-stop switch is disconnected, the voltage generated by braking is discharged through the braking unit, so that the brushless motor can rapidly stop rotating, the braking efficiency is improved, and the use safety of the electric tool is ensured.

Description

Brushless motor control system and electric tool

Technical Field

The utility model relates to the technical field of electric tool control, in particular to a brushless motor control system and an electric tool.

Background

The cutting machine is an electric cutting tool applied to the fields of hardware, petrochemical industry, metallurgy, electric installation and the like, can be used for cutting metal or nonmetal materials, and has the characteristics of portability, convenience and flexibility in work, wide application range and the like.

The cutting machine is generally provided with a controller for intelligent control, the existing controller is large in size, so that the cutting machine is heavy, the service life of the cutting machine is prolonged in order to reduce the size of the cutting machine controller, and the brushless motor is used as a power source to be applied to the cutting machine in the market. In the prior art, when a brushless motor is braked, by controlling each winding in a stator winding of the brushless motor to be short-circuited and generating electromotive force in the stator winding, a magnetic field for preventing the rotor from rotating is generated around the stator winding according to the electromotive force, so that the rotor consumes self kinetic energy under the action of the magnetic field, and further, the braking control of the brushless motor is achieved. However, the rotor is required to completely consume the kinetic energy of the rotor under the action of the magnetic field so as to realize braking. Therefore, the problem of low braking efficiency exists that rapid and reliable braking cannot be realized, and the device is still damaged in the braking process.

In view of the foregoing, there is a need for a brushless motor control system and an electric tool that can improve braking efficiency.

Disclosure of Invention

The utility model aims to solve the defects of the technology, and provides a brushless motor control system and an electric tool.

The utility model relates to a brushless motor control system, which comprises a main control unit, a PFC control unit, a motor driving unit, a brushless motor, a braking unit, a start-stop switch and a power supply unit, wherein the main control unit is respectively and electrically connected with the PFC control unit, the motor driving unit and the power supply unit; the power supply unit comprises an AC/DC conversion module and a DC/DC conversion module, wherein the rectification output end of the AC/DC conversion module is electrically connected with the input end of the DC/DC conversion module, the output end of the DC/DC conversion module is electrically connected with the main control unit, the braking unit is respectively electrically connected with the DC/DC conversion module and the main control unit, and the start-stop switch is respectively electrically connected with the main control unit and the DC/DC conversion module.

Further, the braking unit comprises a control chip, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first triode, a second triode, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a first diode, wherein the base electrode of the first triode is electrically connected with the control chip, the collector electrode of the first triode and the source electrode of the second triode are respectively connected with a protective ground, the second resistor is arranged between the emitter electrode of the first triode and the grid electrode of the second triode, the first resistor is further arranged between the control chip and the second end part of the second resistor, a second capacitor is arranged between the control chip and the protective ground, the fifth resistor and the third capacitor which are connected in parallel are arranged between the grid electrode of the second triode and the collector electrode of the first triode, and the braking resistor is arranged between the drain electrode of the second triode and the protective ground;

the control chip and the signal ground are sequentially connected in series with a first diode and a first capacitor, the anode of the first diode is electrically connected with the DC/DC conversion module, a fourth resistor is connected in series between the control chip and the main control unit, a third resistor is arranged between the control chip and the protection ground, and a sixth resistor and a fourth capacitor which are connected in parallel are respectively arranged between the control chip and the signal ground.

Further, the device also comprises an input voltage detection unit which is respectively and electrically connected with the rectification output end of the AC/DC conversion module and the main control unit.

Further, the device also comprises a high-voltage direct current detection unit which is respectively and electrically connected with the direct current output end of the AC/DC conversion module and the main control unit.

Further, the power supply unit further comprises a current impact prevention module, and the current impact prevention module is electrically connected with the AC/DC conversion module, the DC/DC conversion module and the main control unit respectively.

Further, the current surge prevention module comprises a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a first relay, a second relay, a third triode, a fourth triode, a second diode and a third diode;

the first end of the ninth resistor is electrically connected with the movable contact of the first relay, the second end of the ninth resistor is electrically connected with the fixed contact of the second relay, the fixed contact of the first relay is electrically connected with the movable contact of the second relay, the fixed contact and the movable contact of the first relay are respectively electrically connected with the AC/DC conversion module, the first end of the first relay coil is electrically connected with the second end of the second relay coil, the second end of the first relay coil is electrically connected with the DC/DC conversion module, the second diode is electrically connected with the second end of the first relay coil and the first end of the second relay coil after being reversely connected with the third diode, the second diode and the third diode are electrically connected with the DC/DC conversion module, a third triode is connected between the positive pole of the second diode and the signal ground in series, the control end of the third triode is respectively connected with the main control unit and the signal ground in series with a seventh resistor and a tenth resistor, the positive pole of the third diode is respectively connected with the signal ground in series with the fourth triode and the eighth triode is respectively connected with the signal ground in series with the eighth resistor.

Further, the motor driving unit comprises an inverter circuit and a driving circuit, wherein the inverter circuit is respectively and electrically connected with the PFC unit, the driving circuit and the brushless motor, and the driving circuit is electrically connected with the main control unit.

Further, the device also comprises a counter potential detection unit which is respectively and electrically connected with the main control unit and the driving circuit.

Further, the display unit comprises a display screen module, an interface module, a receiving module and a transmitting module, wherein the interface module is respectively and electrically connected with the receiving module, the transmitting module, the start-stop switch, the DC/DC conversion module and the display screen module, and the receiving module and the transmitting module are respectively and electrically connected with the main control unit and the DC/DC conversion module.

The utility model designs an electric tool which comprises the brushless motor control system.

According to the brushless motor control system and the electric tool, the PFC unit synchronizes the voltage phase and the current phase, improves the power utilization rate, reduces reactive power loss, and stably and reliably controls the working state of the brushless motor through the motor driving unit. When the main control unit detects that the start-stop switch is disconnected, the voltage generated by braking is discharged through the braking unit, so that the brushless motor can rapidly stop rotating, the braking efficiency is improved, and the use safety of the electric tool is ensured.

Drawings

FIG. 1 is a block diagram of the control system of a brushless motor of the present disclosure;

fig. 2 is a schematic circuit diagram of an AC/DC conversion module, a PFC unit, and a PFC control unit;

FIG. 3 is a schematic circuit diagram of a DC/DC conversion module;

FIG. 4 is a schematic circuit diagram of the master control unit, brake unit, display unit and start-stop switch;

FIG. 5 is a schematic circuit diagram of each detection cell;

fig. 6 is a schematic circuit diagram of a motor drive unit;

fig. 7 is a schematic circuit diagram of a current surge protection module.

In the figure: 1. a main control unit; 2. a PFC unit; 3. a PFC control unit; 4. a motor driving unit; 41. the inverter circuit, 42, the driving circuit, 5, brushless motor; 6. a braking unit; 7. the device comprises a start-stop switch 8, a power supply unit 81, an AC/DC conversion module 82, a DC/DC conversion module 83, a current surge prevention module 9, an input voltage detection unit 10, a high-voltage direct current detection unit 11, a counter-potential detection unit 12, a display screen module 13, an interface module 14, a receiving module 15, a transmitting module 16, a temperature acquisition unit 17 and a fault indicator lamp unit.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which are derived by a person skilled in the art based on the embodiments of the utility model, fall within the scope of protection of the utility model.

Example 1:

as shown in fig. 1, the brushless motor control system described in this embodiment includes a main control unit 1, a PFC unit 2, a PFC control unit 3, a motor driving unit 4, a brushless motor 5, a brake unit 6, a start-stop switch 7, and a power supply unit 8, where the main control unit 1 is electrically connected to the PFC control unit 3, the motor driving unit 4, and the power supply unit 8, and the PFC unit 2 is electrically connected to the PFC control unit 3, the motor driving unit 4, and the power supply unit 8, and the motor driving unit 4 is electrically connected to the brushless motor 5; the power supply unit 8 comprises an AC/DC conversion module 81 and a DC/DC conversion module 82, wherein the rectification output end of the AC/DC conversion module 81 is electrically connected with the input end of the DC/DC conversion module 82, the output end of the DC/DC conversion module 82 is electrically connected with the main control unit 1, the brake unit 6 is respectively electrically connected with the DC/DC conversion module 82 and the main control unit 1, and the start-stop switch 7 is respectively electrically connected with the main control unit 1 and the DC/DC conversion module 82. In normal operation, the brake unit 6 is in an off state.

As shown IN fig. 2, IN the AC/DC conversion module 81, AC power is input to the circuit boards through IN-L and IN-N, VDR1 is a varistor to prevent instantaneous high voltage from the power grid from damaging the subsequent circuit; the capacitor C1, the capacitor C8, the resistor R3, the resistor R6, the inductor L1, the capacitor C5 and the capacitor C110 are safety elements, and interference from a power grid and interference of a circuit are suppressed; DP1 is a rectifier bridge, rectifying the ac full wave to dc, and capacitor C6 and capacitor C7 are energy storage filters, converting pulsating dc to constant dc. The L position of the inductor L1 is a network interface, and the DZTX position of the capacitor C110 is connected to the housing.

In the PFC unit 2, high-voltage direct current flows in from rect+ point, when power is started, current flows to the back-stage capacitor C15, capacitor C16, capacitor C17, capacitor C111 and capacitor C14 through the diode D23, when the voltage rises to a set value, the 17 pin of the chip U7 of the PFC control unit 3 outputs a PWM signal, the signal is sent to the triode Q3 through the chip U2, when the triode Q3 is opened, current flows to the power supply negative electrode through the inductor L4, the triode Q3, the resistor R31 and the resistor R34, when current flows through the inductor, the current is blocked by the inductor, when the current reaches the saturation of the inductor, the chip U7 of the PFC control unit 3 closes the output, the current in the inductor cannot break, the current is overlapped through the back-stage capacitor of the diode D6, when the input voltage and the reverse voltage generated by the inductor are overlapped together, and when the chip U7 of the PFC control unit 3 checks that the voltage on the back-stage capacitor exceeds 400V, the chip U7 of the PFC control unit 3 reduces the 17 pin output PWM signal, and the phase of the current phase of the PFC control unit is blocked by the inductor.

As shown in fig. 3, in the DC/DC conversion module 82, high-voltage direct current is applied to the transformer T1, the resistor R16 and the resistor R21 provide a starting voltage for the chip U5 of the DC/DC conversion module 82, the voltage charges the capacitor C25, the capacitor C27 and the capacitor C30 through the resistor R16 and the resistor R21, when the voltage reaches 7.3V, the pin 6 of the chip U5 starts to output PWM signals, the transistor Q5 starts to open, the voltage is coupled to other windings through the transformer T1, the resistor R52 is a current feedback function, the diode Z2, the resistor R43, the resistor R50, the transistor Q6 and the resistor R42 form a voltage feedback circuit, and the three rectifying diodes D3, D7 and D10 rectify the alternating current on the secondary winding of the transformer T1 into direct current to supply power to the system itself, so that under any voltage conditions, the working power of the brushless motor can be ensured, and stable and reliable power supply can be ensured.

As shown in fig. 4, the brake unit 6 includes a control chip U8, a first resistor R85, a second resistor R86, a third resistor R90, a fourth resistor R93, a fifth resistor R94, a sixth resistor R99, a first triode Q17, a second triode Q19, a first capacitor C74, a second capacitor C75, a third capacitor C80, a fourth capacitor C83, and a first diode D14, wherein a base electrode of the first triode Q17 is electrically connected to the control chip U8, a collector electrode of the first triode Q17 and a source electrode of the second triode Q19 are respectively connected to a protection ground PGND, a second resistor R86 is disposed between an emitter electrode of the first triode Q17 and a gate electrode of the second triode Q19, a first resistor R85 is further disposed between the control chip U8 and a second end of the second resistor R86, a second capacitor C75 is disposed between the control chip U8 and the protection ground PGND, a fifth resistor R94 connected in parallel is disposed between a gate electrode of the second triode Q19 and the first triode Q17, and a drain electrode of the third triode Q19 is disposed between the protection ground PGND and the third resistor Q80;

the control chip U8 and the signal ground SGND are sequentially connected in series with a first diode D14 and a first capacitor C74, the anode of the first diode D14 is electrically connected with the DC/DC conversion module 82, the control chip U8 and the main control unit 1 are connected in series with a fourth resistor R93, a third resistor R90 is arranged between the control chip U8 and the protection ground PGND, and a sixth resistor R99 and a fourth capacitor C83 which are mutually connected in parallel are respectively arranged between the control chip U8 and the signal ground SGND.

When the control chip U14 of the main control unit 1 detects that the start-stop switch 7 is disconnected, PWM output is stopped, three power lines of the motor are short-circuited, the motor stops rotating as soon as possible, because the motor winding is an inductor, one end of the motor is short-circuited, the voltage is equivalent to the boost inductor and is superimposed on the capacitor, the voltage is discharged through a resistor, and the larger the discharge current is, the more obvious the braking effect is.

As shown in fig. 5, the device further includes an input voltage detection unit 9 electrically connected to the rectification output terminal of the AC/DC conversion module 81 and the main control unit 1, a high voltage DC detection unit 10 electrically connected to the DC output terminal of the AC/DC conversion module 81 and the main control unit 1, and a counter potential detection unit 11 electrically connected to the main control unit 1 and the driving circuit 42.

The main control unit 1 is a singlechip, acquires various voltage parameters through an IO port, judges through internal program operation and adjusts the output of six paths of PWM signals. In the input voltage detection unit 9, rect+ is an ac rectified voltage, and the voltage is divided and sent to the main control unit 1 to inform the amplitude of the input voltage, and in the high voltage dc detection unit 10, +311V is a PFC output voltage, the main control unit 1 calculates two sampling voltages. When the RECT+ voltage division is too small, the input voltage is too low, the operation is not suitable, and the main control unit 1 stops outputting. When the +311V divided voltage is less than the set point, indicating that the voltage is insufficient, the PWM output time is increased, and when the +311V divided voltage is greater than the set point, indicating that the voltage is too high, the PWM output should be reduced or turned off.

In the counter potential detecting unit 11, U, V, W three-phase line counter electromotive force is collected, and by detecting the timings of the three counter potentials, the rotor position can be determined so as to accurately control the operation state of the brushless motor.

Preferably, the temperature acquisition unit 16 and the fault indicator unit 17 are further included, which are electrically connected with the main control unit 1 and the DC/DC conversion module 82, respectively. The main control unit 1 performs corresponding control operations, such as alarm, shutdown, etc., when the temperature reaches the set value.

As shown in fig. 7, the power supply unit 8 further includes a current surge prevention module 83, and the current surge prevention module 83 is electrically connected to the AC/DC conversion module 81, the DC/DC conversion module 82, and the main control unit 1, respectively.

Specifically, the current surge prevention module 83 includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R11, a tenth resistor R14, an eleventh resistor R15, a first relay J1, a second relay J2, a third triode Q1, a fourth triode Q2, a second diode D4, and a third diode D5;

the first end of the ninth resistor R11 is electrically connected with the movable contact of the first relay J1, the second end of the ninth resistor R11 is electrically connected with the fixed contact of the second relay J2, the fixed contact of the first relay J1 is electrically connected with the movable contact of the second relay J2, the fixed contact and the movable contact of the first relay J1 are respectively electrically connected with the AC/DC conversion module 81, the first end of the coil of the first relay J1 is connected with the second end of the coil of the second relay J2, the second diode D4 is reversely connected with the third diode D5 and then is respectively electrically connected with the second end of the coil of the first relay J1 and the first end of the second relay coil J2, the second diode D4 and the third diode D5 are electrically connected with the +16V5_P of the DC/DC conversion module 82, the positive pole of the second diode D4 is respectively connected with the signal ground SGND in series with a third triode Q1, the control end of the third triode Q1 is respectively connected with the control unit SGR 1, the signal SGR 7 is connected with the signal ground, the signal SGR 2 is respectively connected with the signal ND, and the signal SGR 2 is connected with the signal ND in series with the fourth triode Q1, the signal SGR 2 is respectively, the signal ND is connected with the signal SGR 2 in series.

The third resistor R11, the first relay J1 and the second relay J2 form a capacitor buffer circuit, no electricity exists in the capacitor at the rear stage of the power-on moment, the circuit is equivalent to a short circuit, the impact of impact current is avoided, and the charging current of the capacitor is limited.

As shown in fig. 6, the motor driving unit 4 includes an inverter circuit 41 and a driving circuit 42, the inverter circuit 41 is electrically connected to the PFC unit 2, the driving circuit 42, and the brushless motor 5, and the driving circuit 42 is electrically connected to the main control unit 1.

The control chip U14 of the main control unit 1 sends 6 paths of PWM signals to the driving chip of the driving circuit 42 through pins 26-31, the driving chip amplifies and isolates the PWM driving signals, and the on states of six switching tubes IGBT in the inverter circuit 41 are controlled to adjust the working state of the brushless motor.

HO1, HO2, HO3 are the upper bridge arm driving end of the inversion current, LO1, LO2, LO3 are the lower bridge arm driving end of the inversion current, if a driving signal is input from HO1 and LO2, a switching tube Q8 and a switching tube Q15 are simultaneously opened, current flows from U to pass through a motor winding and then flows from V to a power supply negative electrode, if the driving signal is input from HO2 and LO1, current flows from V to pass through the motor winding and then flows from U to the power supply negative electrode, the current direction is V to U, the change of the current direction of the motor winding can be realized under the assumption that the magnetic field directions generated by windings in different current directions are opposite, and the rotation of a rotor is realized through attraction and repulsion of a stator magnetic field and a rotor magnetic field.

As shown in fig. 4, the display unit further includes a display screen module 12, an interface module 13, a receiving module 14, and a transmitting module 15, where the interface module 13 is electrically connected with the receiving module 14, the transmitting module 15, the start-stop switch 7, the DC/DC conversion module 82, and the display screen module 12, and the receiving module 14 and the transmitting module 15 are electrically connected with the main control unit 1 and the DC/DC conversion module 82, respectively. The receiving module 14 and the transmitting module 15 are used for carrying out data transmission between the display screen and the singlechip, and are communicated with the display screen module 12 through an optical coupler, and the optical coupler realizes electrical isolation so as to improve the use safety of the system.

The utility model also provides an electric tool, which comprises the brushless motor control system. The electric tool is a cutting machine, a water pump, a deep well pump and the like.

The present utility model is not limited to the above-described preferred embodiments, and any person who can obtain other various products under the teaching of the present utility model, however, any change in shape or structure of the product is within the scope of the present utility model, and all the products having the same or similar technical solutions as the present application are included.

Claims (10)

1. A brushless motor control system, characterized in that: the intelligent control device comprises a main control unit (1), a PFC unit (2), a PFC control unit (3), a motor driving unit (4), a brushless motor (5), a braking unit (6), a start-stop switch (7) and a power supply unit (8), wherein the main control unit (1) is respectively electrically connected with the PFC control unit (3), the motor driving unit (4) and the power supply unit (8), the PFC unit (2) is respectively electrically connected with the PFC control unit (3), the motor driving unit (4) and the power supply unit (8), and the motor driving unit (4) is electrically connected with the brushless motor (5); the power supply unit (8) comprises an AC/DC conversion module (81) and a DC/DC conversion module (82), wherein the rectification output end of the AC/DC conversion module (81) is electrically connected with the input end of the DC/DC conversion module (82), the output end of the DC/DC conversion module (82) is electrically connected with the main control unit (1), the braking unit (6) is respectively electrically connected with the DC/DC conversion module (82) and the main control unit (1), and the start-stop switch (7) is respectively electrically connected with the main control unit (1) and the DC/DC conversion module (82).

2. A brushless motor control system as claimed in claim 1, wherein: the braking unit (6) comprises a control chip, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first triode, a second triode, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor and a first diode, wherein the base electrode of the first triode is electrically connected with the control chip, the collector electrode of the first triode and the source electrode of the second triode are respectively connected with a protective ground, the second resistor is arranged between the emitter electrode of the first triode and the grid electrode of the second triode, the first resistor is further arranged between the control chip and the second end part of the second resistor, a second capacitor is arranged between the control chip and the protective ground, the fifth resistor and the third capacitor which are connected in parallel are arranged between the grid electrode of the second triode and the collector electrode of the first triode, and the braking resistor is arranged between the drain electrode of the second triode and the protective ground;

the control chip and the signal ground are sequentially connected in series with a first diode and a first capacitor, the anode of the first diode is electrically connected with a DC/DC conversion module (82), a fourth resistor is connected in series between the control chip and the main control unit (1), a third resistor is arranged between the control chip and the protection ground, and a sixth resistor and a fourth capacitor which are connected in parallel are respectively arranged between the control chip and the signal ground.

3. A brushless motor control system as claimed in claim 1, wherein: the device also comprises an input voltage detection unit (9) which is electrically connected with the rectification output end of the AC/DC conversion module (81) and the main control unit (1) respectively.

4. A brushless motor control system as claimed in claim 1, wherein: the high-voltage direct current detection unit (10) is respectively and electrically connected with the direct current output end of the AC/DC conversion module (81) and the main control unit (1).

5. A brushless motor control system as claimed in any one of claims 1 to 4, wherein: the power supply unit (8) further comprises a current impact prevention module (83), and the current impact prevention module (83) is electrically connected with the AC/DC conversion module (81), the DC/DC conversion module (82) and the main control unit (1) respectively.

6. A brushless motor control system as claimed in claim 5, wherein: the current surge prevention module (83) comprises a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a first relay, a second relay, a third triode, a fourth triode, a second diode and a third diode;

the first end of the ninth resistor is electrically connected with the movable contact of the first relay, the second end of the ninth resistor is electrically connected with the movable contact of the second relay, the movable contact of the first relay is electrically connected with the movable contact of the second relay, the movable contact and the fixed contact of the first relay are respectively electrically connected with the AC/DC conversion module (81), the first end of the first relay coil is electrically connected with the second end of the second relay coil, the second diode and the third diode are respectively electrically connected with the second end of the first relay coil and the first end of the second relay coil after being reversely connected, the second diode and the third diode are respectively electrically connected with the DC/DC conversion module (82), the positive electrode of the second diode is respectively connected with the signal ground in series with the third transistor, the control end of the third diode is respectively connected with the master control unit (1) and the signal ground in series with the seventh resistor and the tenth resistor, the positive electrode of the third diode is respectively connected with the signal ground in series with the eighth transistor, and the positive electrode of the fourth transistor is respectively connected with the signal ground in series with the eighth resistor.

7. A brushless motor control system as claimed in any one of claims 1 to 4, wherein: the motor driving unit (4) comprises an inverter circuit (41) and a driving circuit (42), wherein the inverter circuit (41) is respectively and electrically connected with the PFC unit (2), the driving circuit (42) and the brushless motor (5), and the driving circuit (42) is electrically connected with the main control unit (1).

8. A brushless motor control system as claimed in claim 7, wherein: the device also comprises a counter potential detection unit (11) which is respectively and electrically connected with the main control unit (1) and the driving circuit (42).

9. A brushless motor control system according to any one of claims 1-5, wherein: the display device comprises a main control unit (1), a display unit (12), an interface module (13), a receiving module (14) and a transmitting module (15), wherein the interface module (13) is respectively electrically connected with the receiving module (14), the transmitting module (15), a start-stop switch (7), a DC/DC conversion module (82) and the display unit (12), and the receiving module (14) and the transmitting module (15) are respectively electrically connected with the main control unit (1) and the DC/DC conversion module (82).

10. An electric tool, characterized in that: a brushless motor control system as claimed in any one of claims 1 to 9.