Electric tool

Abstract

The utility model relates to an electric tool which comprises a rectifier bridge, a motor, a driver, a correction module and a cooling element, the correction module comprises a plurality of capacitors and a correction access, and the correction access is connected among the capacitors to control connection of the capacitors and the motor; the cooling element is arranged on one side of the correction module to cool the correction module, when the electric tool is in a first working state of the motor load, the driver accesses the power supply voltage input by the rectifier bridge to directly supply power to the motor, and when the electric tool is in a second working state of the motor load, the driver directly supplies power to the motor. Power voltage input to the driver by the rectifier bridge is corrected by the correction module and then is discharged through the capacitor to supply power to the motor. The power supply condition of the motor can be adjusted in different working states of the motor, so that the effective working time of the motor can be prolonged, the power of the whole system of the electric tool is increased, and the high-efficiency and high-power-factor speed range is expanded.

Description

Technical Field

[0001] The present disclosure relates to the technical field of motors, and particularly to power tools. Background Art

[0002] In life and work, power tools are used more and more frequently. At present, for the improvement of power tools, the focus is on how to improve power, power factor, and electromagnetic compatibility level. Summary of the Utility Model

[0003] To overcome the problems existing in the related art, the present disclosure provides a power tool.

[0004] A power tool according to an embodiment of the present disclosure includes: a rectifier bridge for inputting a power supply voltage;

[0005] a motor for driving a tool head;

[0006] a driver for controlling the motor, the driver being connected between the rectifier bridge and the motor;

[0007] a correction module, the correction module including a plurality of capacitors and a correction path, the correction path being connected between the plurality of capacitors to control the connection between the capacitors and the motor; and

[0008] a cooling element disposed on one side of the correction module to cool the correction module;

[0009] Wherein, when the power tool is in a first working state of the motor load, the driver accesses the power supply voltage input by the rectifier bridge to directly supply power to the motor;

[0010] When the power tool is in a second working state of the motor load, the power supply voltage input from the rectifier bridge to the driver is corrected by the correction module and then discharged through the capacitor to supply power to the motor.

[0011] In some embodiments, the driver includes a bus capacitor;

[0012] The capacitance value of the bus capacitor is less than 1 / 3 of the capacitance value of the capacitor in the correction module.

[0013] In some embodiments, the product of the capacitance value of the bus capacitor and the capacitance value of the capacitor, in the unit of microfarad, is less than twenty-five times the value of the highest current value of the driver in the steady state in the unit of ampere.

[0014] In some embodiments, the ratio of the capacitance value of the capacitor, in the unit of microfarad, to the value of the highest current value of the driver in the steady state in the unit of ampere is greater than or equal to 0.5.

[0015] In some embodiments, the cooling element includes a cooling fan;

[0016] The motor is connected to the cooling fan, and the motor is used to drive the cooling fan.

[0017] In some embodiments, the rated no-load speed of the motor is less than the maximum speed of the motor;

[0018] The ratio of the rated no-load speed to the loaded speed of the motor in the second operating state is 1 - 1.8; and / or

[0019] The ratio of the loaded speed of the motor in the first operating state to the loaded speed of the motor in the second operating state is 1 - 1.8.

[0020] In some embodiments, the first operating state and the second operating state occur alternately within a half-wave of the power supply voltage;

[0021] In the first operating state, the back electromotive force voltage of the motor is greater than 1 / 2 of the amplitude of the power supply voltage;

[0022] In the second operating state, the back electromotive force voltage of the motor is less than 1 / 2 of the amplitude of the power supply voltage.

[0023] In some embodiments, in the first operating state, the integral of the current of the motor with respect to time, and the integral of the charging current of the capacitor with respect to time have a ratio of 1.5 - 4.

[0024] In some embodiments, in the second operating state, the amplitude of the current of the motor, and the amplitude of the discharging current of the capacitor have a ratio of 0.5 - 2.

[0025] In some embodiments, in the second operating state, the discharging depth of the capacitor is below 50%.

[0026] In some embodiments, when the motor is operating under no-load or light-load, it is in the first operating state, and the speed of the motor is greater than the maximum speed.

[0027] In some embodiments, in the first operating state, the power angle or the advance commutation angle of the motor is 0° - 35°;

[0028] In the second operating state, the power angle or the advance commutation angle of the motor is 30° - 60°.

[0029] In some embodiments, the back electromotive force waveform of the motor is sinusoidal;

[0030] The motor commutes when the back electromotive force drops to 90% - 60% of the peak value.

[0031] In some embodiments, the plurality of capacitors include a first capacitor (C1) and a second capacitor (C2) connected in parallel with each other;

[0032] The correction path includes a first switch (D1), a second switch (D2), and a third switch (D3) connected in series with each other. A first end of the first capacitor and the first switch are connected to the positive electrode of the rectifier bridge, and a second end of the second capacitor and the third switch are connected to the driver;

[0033] One end of the second switch is connected to a connection node between the first switch and a first end of the second capacitor, and the other end of the second switch is connected to a connection node between the third switch and a second end of the first capacitor.

[0034] In some embodiments, the first switch includes a diode, or a MOS, or a bipolar transistor. The first switch is configured such that when the first capacitor and the second capacitor are charged in series, the first switch conducts to charge the second capacitor;

[0035] The second switch and the third switch include diodes.

[0036] In some embodiments, the power tool includes a first circuit board and a second circuit board;

[0037] The driver is disposed on the first circuit board, and the correction module is disposed on the second circuit board.

[0038] In some embodiments, a first inductive element and / or a second inductive element are further included;

[0039] The rectifier bridge is connected to the correction module through the first inductive element;

[0040] The correction module is connected to the bus capacitor through the second inductive element.

[0041] In some embodiments, the first inductive element includes a first wire and a second wire;

[0042] Two ends of the first wire are respectively connected to the rectifier bridge and the correction module, two ends of the second wire are respectively connected to the rectifier bridge and the correction module, and the first wire and the second wire have equivalent mutual inductance or equivalent self-inductance;

[0043] The second inductive element includes a third wire and a fourth wire;

[0044] Both ends of the third wire are respectively connected to the correction module and the bus capacitor, both ends of the fourth wire are respectively connected to the correction module and the bus capacitor, and the third wire and the fourth wire have equivalent mutual inductance or equivalent self-inductance.

[0045] The technical solutions provided by the embodiments of the present disclosure may include the following beneficial effects: The correction module in the present disclosure includes multiple capacitors and a correction path. The correction path is connected between the multiple capacitors to control the connection between the capacitors and the motor. When the power tool is in the first working state of motor load, the driving circuit accesses the power supply voltage input by the rectifier bridge to directly supply power to the motor. When the power tool is in the second working state of motor load, the power supply voltage input from the rectifier bridge to the driving circuit is corrected by the correction module and then discharges through the capacitor to supply power to the motor. With the setting of the present disclosure, the power supply situation for the motor can be adjusted under different working states of the motor, so that the effective working time of the motor can be increased, and thus the overall power of the overall system of the power tool can be increased.

[0046] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure.

[0048] Figure 1 is a block diagram of a power tool shown according to an exemplary embodiment.

[0049] Figure 2 is a schematic structural diagram of a power tool shown according to an exemplary embodiment.

[0050] Figure 3 is a schematic structural diagram of a power tool shown according to another exemplary embodiment.

[0051] Figure 4 is a schematic diagram of the element layout of a power tool shown according to an exemplary embodiment.

[0052] Figure 5 is a schematic diagram of the element layout of a power tool shown according to another exemplary embodiment.

[0053] Figure 6 is a block diagram of a power tool shown according to another exemplary embodiment.

[0054] Figure 7 is a curve diagram of the back electromotive force and electrical angle of a motor shown according to an exemplary embodiment.

[0055] Figure 8 It is a graph showing the heat dissipation capacity, power, and current of a power tool according to an exemplary embodiment.

[0056] Figure 9 It is a graph showing the power and current of a power tool according to another exemplary embodiment.

[0057] Figure 10 It is a graph showing the power and current of a power tool according to another exemplary embodiment.

[0058] Figure 11 It is a graph showing the power and current of a power tool according to another exemplary embodiment.

[0059] Figure 12 It is a graph showing the power and current of a power tool according to another exemplary embodiment.

[0060] Figure 13 It is a block diagram of a power tool according to an exemplary embodiment.

[0061] Figure 14 is Figure 13 an equivalent schematic diagram of Detailed Description of the Invention

[0062] Here, exemplary embodiments will be described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0063] In life and work, power tools are used more and more frequently. Currently, regarding the improvement of power tools, the focus is on how to increase power.

[0064] To overcome the problems in the related art, the present disclosure provides a power tool 10.

[0065] An electric tool 10 provided according to an embodiment of the present disclosure includes: a rectifier bridge 100 for inputting a power supply voltage; a motor 400 for driving a tool head 600; a driver 300 for controlling the motor 400, the driver 300 being connected between the rectifier bridge 100 and the motor 400; a correction module 200, the correction module 200 including a plurality of capacitors and a correction path, the correction path being connected between the plurality of capacitors to control the connection between the capacitors and the motor 400; and a cooling element 500 disposed on one side of the correction module 200 to cool the correction module 200. Wherein, when the electric tool 10 is in a first operating state of the motor 400 load, the driver 300 accesses the power supply voltage input by the rectifier bridge 100 and directly supplies power to the motor 400. When the electric tool 10 is in a second operating state of the motor 400 load, the power supply voltage input from the rectifier bridge 100 to the driver 300 is corrected by the correction module 200 and then discharges through the capacitor to supply power to the motor 400.

[0066] The correction module 200 in the present disclosure includes a plurality of capacitors and a correction path. The correction path is connected between the plurality of capacitors to control the connection between the capacitors and the motor 400. When the electric tool 10 is in a first operating state of the motor 400 load, the drive circuit accesses the power supply voltage input by the rectifier bridge 100 and directly supplies power to the motor 400. When the electric tool 10 is in a second operating state of the motor 400 load, the power supply voltage input from the rectifier bridge 100 to the drive circuit is corrected by the correction module 200 and then discharges through the capacitor to supply power to the motor 400. With the arrangement of the present disclosure, the power supply situation of the motor 400 can be adjusted under different operating states of the motor 400, so that the effective operating time of the motor 400 can be increased, and thus the overall power of the overall system of the electric tool 10 can be increased.

[0067] Figure 1 is a block diagram of an electric tool 10 shown according to an exemplary embodiment Figure 2 is a schematic structural diagram of an electric tool 10 shown according to an exemplary embodiment Figure 3 is a schematic structural diagram of an electric tool 10 shown according to another exemplary embodiment. As Figures 1 to 3 shown, the electric tool 10 may include a rectifier bridge 100, a driver 300, a correction module 200, a cooling element 500, and a motor 400. In the present disclosure, the driver 300 may be connected between the rectifier bridge 100 and the motor 400, the correction module 200 may be connected between the rectifier bridge 100 and the driver 300, and the driver 300 is connected to the motor 400.

[0068] As Figure 2 and Figure 3As shown, the cooling element 500 can be used to cool down the calibration module 200. For example, the cooling element 500 can be arranged on one side of the calibration module 200. The calibration module 200 can be arranged on a circuit board, and the cooling element 500 can be arranged on one side of the circuit board.

[0069] In the present disclosure, the cooling element 500 can be a cooling fan.

[0070] Figure 4 is a schematic diagram of the element arrangement of a power tool 10 shown according to an exemplary embodiment. Figure 5 is a schematic diagram of the element arrangement of a power tool 10 shown according to another exemplary embodiment. As Figure 4 and Figure 5 shown, different elements in the power tool 10 can be arranged on different circuit boards.

[0071] For example, there can be an arrangement where all power devices are placed on the second circuit board 102 (patch board), and other parts with more plug-ins are placed on the first circuit board 101. For example, the power supply and electromagnetic interference (EMI) filtering part can be arranged on the first circuit board 101. For example, the driver 300 can be arranged on the first circuit board 101, and the capacitors in the calibration module 200 can be arranged on the second circuit board 102. The cooling element 500 can be arranged on one side of the second circuit board 102 to cool down the calibration module.

[0072] As Figure 2 and Figure 3 shown, the first circuit board 101 and the second circuit board 102 can be separately arranged. On the one hand, it can leave space for arranging the cooling element 500. On the other hand, such an arrangement can also be applicable to power tools 10 with different shapes. For example, the first circuit board 101 and the second circuit board 102 can be arranged adjacent to each other.

[0073] As Figure 3 shown, the power tool 10 can have a grip portion in an L shape, and the first circuit board 101 and the second circuit board 102 can be respectively located on two sides of the L shape.

[0074] In the present disclosure, the cooling element 500 can be a heat sink 501, and the heat sink 501 is arranged on the second circuit board 102 to cool down the capacitors in the calibration module. In some embodiments, the cooling element 500 can also be arranged corresponding to the capacitors in the calibration module to further efficiently and precisely cool down the capacitors.

[0075] In the present disclosure, the rectifier bridge 100 is used to access the power supply voltage, and the rectifier bridge 100 can have a positive electrode ac1+ and a negative electrode ac1-.

[0076] AsFigure 2 and Figure 3 As shown in Figure 3 , the power tool 10 can be a cutting tool, and the motor 400 rotates to drive the tool head 600 to rotate. Depending on the type of the power tool 10, the tool head 600 can be different components. For example, the power tool 10 can be an angle grinder or a straight grinder, and the tool head 600 can be a grinding disc. The power tool 10 can be a drill, and the tool head 600 can be a drill bit.

[0077] In the present disclosure, the correction module 200 can include a plurality of capacitors and a correction path, and the correction path can be connected between the plurality of capacitors to control the connection between the capacitors and the motor 400. For example, when the power tool 10 is in the first working state of the load of the motor 400, the driving circuit accesses the power supply voltage input by the rectifier bridge 100 and directly supplies power to the motor 400. When the power tool 10 is in the second working state of the load of the motor 400, the power supply voltage input from the rectifier bridge 100 to the driver 300 is corrected by the correction module 200 and then discharges through the capacitor to supply power to the motor 400.

[0078] During the use of the power tool 10, when there is a load on the motor 400, such as when the load is light, the speed of the motor 400 is relatively high, and it can be directly powered by the rectifier bridge 100. When the load is heavy, the speed of the motor 400 is relatively low, and it can be powered by discharging through the capacitor after being corrected by the calibration module. In the present disclosure, through the setting of the switching element, the correction module charges the capacitors in series and discharges the capacitors in parallel.

[0079] As described above, in the present disclosure, the first working state can be defined as a light load or a relatively high speed of the motor 400. For example, when the power tool 10 is a drill, such as when the load is a small-bit drill bit, it can be directly powered by the power supply, that is, the power supply voltage input by the rectifier bridge 100 directly supplies power to the motor 400. In this case, with a higher power supply voltage amplitude, the tool can be driven to operate at a high speed, and the working speed can be increased.

[0080] The second working state can be defined as a heavy load or a relatively low speed of the motor 400. When the power tool 10 is a drill, such as when the load is a large-bit or reaches the large-torque state, the power supply voltage input from the rectifier bridge 100 to the driving circuit is corrected by the correction module 200 and then discharges through the capacitor to supply power to the motor 400. That is, when the speed is reduced, the power of the capacitor of the calibration module can be increased, and additional torque can be increased without significantly increasing the current. The speed range is wide.

[0081] According to such a setting, when the motor 400 rotates at a high speed, the capacitor does not participate in discharging. It works at a high speed with a higher power supply voltage. After field weakening, the light-load speed is even higher. When the motor 400 rotates at medium and low speeds, the capacitor is connected to discharge. The current on the driving side does not increase, but the working time increases. The torque power is large and the cost is low.

[0082] In some embodiments, for example, a high-power cutting machine (especially a brushless cutting machine with a power greater than 3000 watts). In the case where the power cord 20 is too long or the grid rigidity is insufficient, actually operating at a low speed can reduce the cutting loss energy of the cutting disc. As long as the capacitance value of the electrolytic capacitor in the calibration module is increased, the duration of the (low-speed) torque can be greatly increased, thereby increasing the load-carrying capacity of the tool. Thus, a relatively high horizontal cutting speed can be achieved under limited power supply capacity.

[0083] In some embodiments, such as Figure 1 As shown, the calibration module 200 can be connected between the rectifier bridge 100 and the driver 300. The plurality of capacitors include a first capacitor C1 and a second capacitor C2 connected in parallel with each other. The calibration path includes a first switch D1, a second switch D2, and a third switch D3 connected in series with each other. The first end of the first capacitor and the first switch are connected to the positive pole of the rectifier bridge 100, the second end of the second capacitor and the third switch are connected to the driver 300, one end of the second switch is connected to the connection node between the first switch and the first end of the second capacitor, and the other end of the second switch is connected to the connection node between the third switch and the second end of the first capacitor.

[0084] In some embodiments, the first switch is a diode or a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), that is, a MOS transistor, or a Bipolar Transistor.

[0085] In some embodiments, the second switch and the third switch are diodes.

[0086] In the present disclosure, the cooling element 500 includes a cooling fan; the motor 400 is connected to the cooling fan, and the motor 400 is used to drive the cooling fan. That is, while the motor 400 drives the tool head 600 to work, it drives the cooling fan to rotate to dissipate heat from the calibration module 200.

[0087] Figure 8 It is a graph showing the heat dissipation capacity, power, and current of an electric tool 10 according to an exemplary embodiment. Figure 8They are respectively a graph of the heat dissipation capacity and the rotational speed of the motor 400, a graph of the power and current of the power tool 10 shown in an exemplary embodiment, and a graph of the power and current of a power tool 10 shown in another exemplary embodiment. As shown in the graph of the heat dissipation capacity and the rotational speed of the motor 400, when the motor 400 drives the cooling fan to rotate for dissipating heat from the correction module 200, the cooling capacity of the cooling fan is proportional to the rotational speed of the motor 400, that is, the higher the rotational speed of the power tool 10, the stronger the cooling capacity of the cooling fan. Furthermore, during the operation of the motor 400, there are respectively a high heat risk interval, a low heat risk interval, and a high-speed interval without heat risk.

[0088] As Figure 8 shown, when the power tool 10 is in the second operating state of the load of the motor 400, the power supply voltage input from the rectifier bridge 100 to the drive circuit is corrected by the correction module 200 and then discharges through the capacitor to supply power to the motor 400. Current A is the current trend of the motor 400 in the prior art, and current B is the current trend of the motor 400 in the present disclosure. The maximum output of A is the maximum output power level of the motor 400 in the prior art, and the maximum output of B is the maximum output power level of the motor 400 in the present disclosure. It can be seen that by configuring the correction module 200, a stronger torque output and a higher maximum output power level can be provided.

[0089] In some embodiments, the capacitor is an electrolytic capacitor to avoid the motor 400 being in a high heat risk interval at the maximum output power level.

[0090] In some embodiments, the capacitance value of the capacitor is 100 uF - 150 uF. For example, the capacitance value of the electrolytic capacitor is 105 uF / 5A (5A is the average current) above 85 degrees. For example, the capacitance value of the electrolytic capacitor is 125 uF / 5A (5A is the average current) above 85 degrees. For example, the capacitance value of the electrolytic capacitor is 130 uF / 5A (5A is the average current) above 85 degrees. By equipping two large electrolytic capacitors (such as greater than 33 uF / 20A) and configuring the back electromotive force of the motor 400 to be lower than 90% - 60% of the bus peak voltage, the system load operating point can be placed in a lower heat risk interval to a greater extent, as Figure 8 shown, in the present disclosure, after slight loading, the electrolytic capacitor can discharge in parallel earlier, that is, enter the working interval of the correction module 200 and be used as the second power supply for driving the motor 400. Throughout the lower heat risk interval, the electrolytic capacitor can provide additional discharge, thereby increasing the working time of the motor 400 and thus improving the external output of the motor 400. Generally speaking, under the condition that the heat risk is controllable, the tool obtains a greater output power, but its current level does not become higher.

[0091] In some embodiments, the driver 300 includes a bus capacitor 310; the capacitance value of the bus capacitor 310 is less than 1 / 3 of the capacitance value of the capacitor in the correction module 200, wherein the bus capacitor 310 is connected in parallel with the driver 300 as a snubber circuit.

[0092] In some embodiments, the product of the capacitance value of the bus capacitor 310 and the capacitance value of the capacitor, in microfarad units, is less than twenty-five times the value of the highest current value of the driver 300 in steady state in ampere units. That is to say, the product of the capacitance values of the bus capacitor 310 and a single electrolytic capacitor, divided by the highest bus current in the system steady state, should be less than 15. For example, a 15 uF electrolytic capacitor with a 2.2 uF bus capacitor 310 can support a system with a maximum bus current of 5 A, 15×2.2 / 5 = 6.6. A 68 uF electrolytic capacitor with a 3.3 uF bus capacitor 310 can support a system with a maximum bus current of 30 A, 68×3.3 / 30 = 7.48. The above-mentioned highest current value in steady state refers to operating continuously at a value lower than the highest allowable current value in 2 to 10 cycles of 10 milliseconds, and is often equal to or greater than the nominal current of the power devices used in the system.

[0093] In some embodiments, the ratio of the capacitance value of the capacitor, in microfarad units, to the highest current value of the driver 300 in steady state in ampere units is greater than or equal to 0.5. That is to say, for every 30 A of bus steady-state current, the capacitance value of the configured capacitor is greater than or equal to 15 uF. The above-mentioned highest current value in steady state refers to operating continuously at a value lower than the highest allowable current value in 2 to 10 cycles of 10 milliseconds, and is often equal to or greater than the nominal current of the power devices used in the system.

[0094] Figure 7 It is a graph showing the back electromotive force and electrical angle of a motor 400 according to an exemplary embodiment. As Figure 7 shown, the motor 400 may have a quasi-sine wave back electromotive force, and the driver 300 may be provided with a square wave drive controller (control module). The motor 400 commutes when the back electromotive force drops to 90% - 60% of its peak value, so as to reduce the back charging energy during commutation, and thus reduce the capacitance value of the bus capacitor 310. When the input voltage reaches the maximum peak and starts to decline, the ratio of the no-load speed to the loaded speed can be strategically increased, and the off-time interval can be reduced, so as to reduce the backrush energy caused by the disconnection of Pulse-Width Modulation (PWM), and thus reduce the bus capacitor 310.

[0095] In some embodiments, the back electromotive force waveform of the motor 400 is sinusoidal.

[0096] In some embodiments, the control module controls the motor 400 to commute when the back electromotive force drops to 90% - 60% of its peak value through square wave control.

[0097] In some embodiments, in the first operating state, the commutation angle of the motor 400 is 30°-40°; in the second operating state, the commutation angle of the motor 400 is 50°-60°. By configuring a motor 400 with a trapezoidal back electromotive force and a square-wave drive controller. Since L*di / dt + back electromotive force voltage = C x dv / dt. The motor 400 commutes when the back electromotive force drops to 90% - 60% of its peak value, so as to reduce the back charging energy during commutation, and further reduce the capacitance value of the bus capacitor 310.

[0098] As Figure 1 shown, the first switch, the second switch and the third switch are diodes.

[0099] In some embodiments, the driver 300 can adopt a very large advance commutation angle, such as 55 degrees, during the working range of the correction module 200, that is, the capacitor discharge stage, so as to actively increase the discharge of the capacitor at a higher rotational speed level. Taking the 220V system as an example, theoretically, at a higher rotational speed or operating point, the additional power provided by the electrolytic capacitor can be utilized.

[0100] In the related art, the power tool does not have a calibration module. When using such a power tool for grinding, the tool stability is poor, resulting in the grinding textures covering each other.

[0101] According to the setting of the present disclosure, the power tool 10 is stable and controllable, and the grinding textures clearly show a concentric circle state. Among grinding tools, the output of the motor 400 is set to be close to the constant speed and constant power situation. The upper and lower charging waveforms are combined. When the voltage is high, the ratio of the no-load rotational speed to the loaded rotational speed is configured to be a large value. Combining the capacitor discharge to supply power to the motor 400 can make the output torque fluctuate within a small range, thereby improving the grinding quality. At the same time, a stable power supply state with a power factor of about 0.9 is formed.

[0102] In some embodiments, as Figure 9 shown, the rated no-load rotational speed of the motor 400 is less than the maximum rotational speed of the motor 400; the ratio of the rated no-load rotational speed to the loaded rotational speed of the motor 400 in the first operating state, or the loaded rotational speed of the motor 400 in the second operating state is 1-1.8; the back electromotive force voltage of the motor 400 is less than half of the amplitude of the power supply voltage. The maximum rotational speed of the motor 400 is the rotational speed at the rated power of the motor 400. When adapting to a tool head 600 with a large mass or reaching a large torque state, after reducing the rotational speed, the power of the capacitor can increase the additional torque without significantly increasing the current.

[0103] In some embodiments, as Figure 11As shown, when the motor is operating under no-load or light-load conditions, it is in the first working state, and the rotational speed of the motor 400 is greater than the maximum rotational speed. When the tool head 600 with a relatively small matching mass or the large torque state is not reached, the capacitor does not discharge. When the motor is operating under no-load or light-load conditions, it is in the first working state, and the rotational speed of the motor 400 can be the field-weakening no-load rotational speed of the motor 400.

[0104] Figure 12 A graph showing the voltage, back electromotive force, and current of a motor 400 according to an exemplary embodiment is as Figure 12 shown. In the present disclosure, at different rotational speeds of the motor 400 corresponding to different back electromotive forces close to 1 / 2 of the power supply amplitude, different driving strategies for the motor 400 are respectively adopted, such that the power directly obtained from the power supply is variable, but the capacitor discharge power or discharge depth is always lower than a certain level or higher than a certain level. Within a certain range, managing the capacitor discharge depth is beneficial to the capacitor life and reduces the probability of capacitor thermal failure. The following figure shows the relative magnitudes and relative time relationships of the power supply voltage, charging current, and direct driving current under the new preferred solution.

[0105] For example, at different rotational speeds of the motor 400 corresponding to different back electromotive forces close to 1 / 2 of the power supply amplitude, different driving strategies for the motor 400 are respectively adopted. The direct power consumption level of the power supply, the active discharge power limit, and the active discharge power improvement effect are achieved by the driving part of the motor 400 by adopting different advance commutation angles (power angles) and different conduction widths (reasonable values between 120° and 150°) during the direct power supply stage and the capacitor power supply stage of the power supply.

[0106] In some embodiments, in the first working state, the power angle or advance commutation angle of the motor 400 is 0° - 35°; in the second working state, the power angle or advance commutation angle of the motor 400 is 30° - 60°.

[0107] In the present disclosure, by defining the behavior within a broad same power supply cycle, within the same power supply cycle, when the power supply voltage is higher than 1 / N of the maximum power supply voltage amplitude, the relationship between the current and voltage of the motor 400 is optimized; when the power supply voltage is lower than 1 / N of the maximum power supply voltage amplitude, the current consumption strategy of the motor 400 is optimized, thereby generating the best power correction and torque rigidity through the synthesis of the motor 400 drive and the charging of the correction module 200.

[0108] In some embodiments, in the first working state, within the same power supply cycle, the power supply voltage is greater than 1 / N of the maximum power supply voltage amplitude. For example, the no-load back electromotive force at the highest speed can be configured to be 60% - 90% of the power supply voltage amplitude. Such a setting can increase the heat dissipation capacity of forced cooling.

[0109] In some embodiments, in the first operating state, within the same power cycle, the power supply voltage is less than or equal to 1 / N of the maximum power supply voltage amplitude. For example, the back electromotive force at the lowest speed operating point is configured to be 20 - 50% of the power supply voltage amplitude.

[0110] In some embodiments, the capacitors in the correction module 200 charge and discharge to correct the power supply voltage; in the second operating state, multiple capacitors discharge to supply power to the motor 400.

[0111] In some embodiments, in the second operating state, the correction path controls the calibration module to make the discharge depth of the capacitors less than 50%.

[0112] In some embodiments, the first operating state and the second operating state alternate within a half - wave of the power supply voltage; in the first operating state, the back electromotive force voltage of the motor 400 is greater than 1 / 2 of the amplitude of the power supply voltage; in the second operating state, the back electromotive force voltage of the motor 400 is less than 1 / 2 of the amplitude of the power supply voltage.

[0113] In some embodiments, in the first operating state, the ratio of the integral of the current of the motor 400 with respect to time to the integral of the charging current of the capacitor with respect to time is 1.5 - 4. Over a large speed range and load range, the power factor on the power supply side is significantly improved.

[0114] In some embodiments, in the first operating state, the ratio of the corresponding area of the charging current envelope to the corresponding area of the current envelope directly supplied by the power supply to the motor is 1 / 2 - 1 / 4. The power factor on the power supply side is significantly improved. Over a large speed range and load range, the power factor on the power supply side is significantly improved.

[0115] In some embodiments, as Figure 12 shown, in the second operating state, the ratio of the current amplitude of the motor to the discharge current amplitude of the capacitor is 0.5 - 2. According to the settings of the present disclosure, the difference between the current amplitude directly supplied by the power supply and the amplitude of the discharge current envelope always remains within a specific range. In the case of gear reduction, when operating at no - load and normal load in medium and low speed gears, the ratio of the no - load speed to the loaded speed when the power supply voltage is high is configured to be a smaller value, so as to achieve a closer torque and speed level compared to when powered by a capacitor, which can keep the output torque fluctuation within a reasonable range, thereby reducing gear impact stress, secondary gear impact, and size noise.

[0116] In some embodiments, in the second operating state, the ratio of the current amplitude of the motor to the discharge current amplitude of the capacitor is 0.5 - 2. Furthermore, the relationship between the current and voltage of the motor 400 is optimized, and the current consumption strategy of the motor 400 is optimized, so that the driving current of the motor 400 in the first operating state and the charging current of the capacitor in the first operating state synthesize to produce an optimal power correction.

[0117] In some embodiments, the first switch is a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), that is, the first switch is MOS transistor Q, and the first switch is configured to conduct to charge the second capacitor when the first capacitor and the second capacitor are charged in series.

[0118] Figure 6 It is a block diagram of a power tool 10 shown according to another exemplary embodiment. As Figure 6 shown, the first switch is MOS transistor Q, and the second switch and the third switch are diodes. Such an arrangement can conduct the first switch to charge the second capacitor when the first capacitor and the second capacitor are charged in series. Thereby increasing the energy storage voltage level of the second capacitor C2 and increasing the power output capacity of the system.

[0119] As Figure 10 shown, by configuring the first switch as MOS transistor Q, the discharge time point of the capacitor is further advanced.

[0120] Preferably, C1 and C2 can be selected with different specifications.

[0121] Preferably, when the capacities of C1 and C2 are comparable, the thermal failure management can be mainly designed for C2.

[0122] Figure 13 It is a block diagram of a power tool 10 shown according to an exemplary embodiment. As Figure 14 shown, in the present disclosure, it further includes a first inductance element 700 and a second inductance element 800; the rectifier bridge 100 is connected to the correction module 200 through the first inductance element 700; the correction module 200 is connected to the bus capacitor 310 through the second inductance element 800.

[0123] Figure 14 is Figure 13 the equivalent schematic diagram of. As Figure 14 shown, the correction module 200 itself is equivalent to a specific capacitor (it has an effect whether D2 is bypassed or not bypassed with a certain impedance). By setting the first inductance element 700 and the second inductance element 800, a first-stage or two-stage filtering circuit is constructed, thereby reducing the electromagnetic compatibility cost. That is, the capacitor 110 on the power supply side, the first inductance element 700, and the capacitor in the correction module 200 constitute a first-stage filter; the capacitor in the correction module 200, the second inductance element 800, and the bus capacitor 310 constitute a second-stage filter.

[0124] In some embodiments, the first inductive element 700 and the second inductive element 800 may be formed by the wire 30, with an equivalent mutual inductance or equivalent self-inductance between the wires 30.

[0125] In some embodiments, the first inductive element 700 includes a first wire and a second wire; the two ends of the first wire are respectively connected to the rectifier bridge 100 and the correction module 200, the two ends of the second wire are respectively connected to the rectifier bridge 100 and the correction module 200, and the first wire and the second wire are arranged adjacent to each other. That is to say, in the power tool 10, the rectifier bridge 100 and the correction module 200 are arranged at intervals, the rectifier bridge 100 and the correction module 200 are respectively connected through the first wire and the second wire, and there is an equivalent mutual inductance or equivalent self-inductance between the first wire and the second wire.

[0126] In some embodiments, the second inductive element 800 includes a third wire and a fourth wire; the two ends of the third wire are respectively connected to the correction module 200 and the bus capacitor 310, the two ends of the fourth wire are respectively connected to the correction module 200 and the bus capacitor 310, and the third wire and the fourth wire are arranged adjacent to each other. That is to say, in the power tool 10, the correction module 200 and the bus capacitor 310 are arranged at intervals, the correction module 200 and the bus capacitor 310 are respectively connected through the third wire and the fourth wire, and there is an equivalent mutual inductance or equivalent self-inductance between the third wire and the fourth wire.

[0127] In some embodiments, there is a differential-mode inductance between the first wire and the second wire. As Figure 14 shown, the differential-mode inductance is formed by the difference in the length direction between the first wire and the second wire, that is, the length of the first wire is greater than or less than the length of the second wire.

[0128] There is a differential-mode inductance between the third wire and the fourth wire. Similarly, the differential-mode inductance is formed by the difference in the length direction between the third wire and the fourth wire, that is, the length of the third wire is greater than or less than the length of the fourth wire.

[0129] It can be understood that in order to implement the above functions, the power tool 10 provided by the embodiments of the present disclosure includes the corresponding hardware structure and / or software module for executing each function. Combining the units and algorithm steps of the examples disclosed in the embodiments of the present disclosure, the embodiments of the present disclosure can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed in the way of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the technical solution of the embodiments of the present disclosure.

[0130] Regarding the device in the above embodiments, the specific manners in which each module performs operations have been described in detail in the embodiments related to the method, and will not be elaborated here.

[0131] It can be understood that "a plurality of" in this disclosure means two or more, and other quantifiers are similar. "And / or" describes the association relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after. The singular forms of "a", "the", and "said" are also intended to include the plural forms unless the context clearly indicates otherwise.

[0132] It can be further understood that the terms "first", "second", etc. are used to describe various information, but this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other, and do not represent a specific order or degree of importance. In fact, the expressions such as "first" and "second" can be used interchangeably. For example, without departing from the scope of this disclosure, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information.

[0133] It can be further understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "front", "rear", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing this embodiment and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation.

[0134] It can be further understood that unless otherwise specified, "connection" includes direct connection without other components between the two, and also includes indirect connection with other elements between the two.

[0135] It can be further understood that although the operations are described in a specific order in the drawings in the embodiments of this disclosure, it should not be understood as requiring these operations to be performed in the specific order or serial order shown, or requiring all the operations shown to obtain the desired result. In a specific environment, multitasking and parallel processing may be beneficial.

[0136] Other embodiments of the present disclosure will be readily apparent to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include known common general knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and examples are only to be considered as exemplary, and the true scope and spirit of the present disclosure are pointed out by the following claims.

[0137] It should be understood that the present disclosure is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present disclosure is only limited by the appended claims.

Claims

1. An electric tool, characterized in that: include: A rectifier bridge for inputting the supply voltage; A motor for driving a tool head; A driver, used for controlling the motor, wherein the driver is connected between the rectifier bridge and the motor; a correction module, the correction module comprising a plurality of capacitors and a correction path, the correction path being connected between the plurality of capacitors to control the connection between the capacitors and the motor; and A cooling element, disposed on one side of the correction module to cool the correction module; Wherein, when the electric tool is in the first working state of the motor load, the driver is connected to the power supply voltage input by the rectifier bridge to directly supply power to the motor; When the electric tool is in the second working state of the motor load, the power supply voltage input from the rectifier bridge to the driver is corrected by the correction module and then discharged through the capacitor to supply power to the motor.

2. The electric tool according to claim 1, characterized in that: The driver includes a bus capacitor; The capacitance of the bus capacitor is less than 1 / 3 of the capacitance of the capacitor in the correction module.

3. The electric tool according to claim 2, characterized in that: The value of the product of the capacitance of the bus capacitor and the capacitance of the capacitor in microfarads is less than twenty-five times the value of the maximum current value of the driver in a steady state in amperes.

4. The electric tool according to claim 1, characterized in that: The ratio of the capacitance value of the capacitor in microfarads to the maximum current value of the driver in amperes in a steady state is greater than or equal to 0.

5.

5. The electric tool according to claim 1, characterized in that: The cooling element includes a heat dissipation fan; The motor is connected to the cooling fan, and the motor is used to drive the cooling fan.

6. The electric tool according to claim 1, characterized in that: The rated no-load speed of the motor is less than the maximum speed of the motor; The ratio of the rated no-load speed to the loaded speed of the motor in the second working state is 1-1.8; and / or The ratio of the loading speed of the motor in the first working state to the loading speed of the motor in the second working state is 1-1.

8.

7. The electric tool according to claim 1, characterized in that: The first working state and the second working state occur alternately within a half-wave of the power supply voltage; In the first working state, the back electromotive force voltage of the motor is greater than 1 / 2 of the power supply voltage; In the second working state, the back electromotive force voltage of the motor is less than 1 / 2 of the power supply voltage.

8. The electric tool according to claim 1, characterized in that: In the first working state, the ratio of the integral of the current of the motor with respect to time to the integral of the charging current of the capacitor with respect to time is 1.5-4.

9. The electric tool according to claim 1, characterized in that: In the second working state, the ratio of the current amplitude of the motor to the discharge current amplitude of the capacitor is 0.5-2.

10. The electric tool according to claim 1, characterized in that: In the second working state, the discharge depth of the capacitor is below 50%.

11. The electric tool according to claim 1, characterized in that: When the electric motor is running at no load or light load, it is in the first working state, and the rotation speed of the motor is greater than the maximum rotation speed.

12. The electric tool according to claim 1, characterized in that: In the first working state, the power angle or advance commutation angle of the motor is 0°-35°; In the second working state, the power angle or advance commutation angle of the motor is 30°-60°.

13. The electric tool according to claim 1, characterized in that: The back EMF waveform of the motor is sinusoidal; The motor commutates when the back electromotive force drops to 90% to 60% of the peak value.

14. The electric tool according to claim 1, characterized in that: The plurality of capacitors include a first capacitor (C1) and a second capacitor (C2) connected in parallel with each other; The correction path comprises a first switch (D1), a second switch (D2), and a third switch (D3) connected in series, a first end of the first capacitor and the first switch are connected to the positive electrode of the rectifier bridge, and a second end of the second capacitor and the third switch are connected to the driver; One end of the second switch is connected to a connection node between the first switch and a first end of the second capacitor, and the other end of the second switch is connected to a connection node between the third switch and a second end of the first capacitor.

15. The electric tool according to claim 14, characterized in that: The first switch comprises a diode or a MOS or a bipolar transistor, and the first switch is configured such that, when the first capacitor and the second capacitor are charged in series, the first switch is turned on to charge the second capacitor; The second switch and the third switch include diodes.

16. The electric tool according to claim 1, characterized in that: The electric tool comprises a first circuit board and a second circuit board; The driver is disposed on the first circuit board, and the correction module is disposed on the second circuit board.

17. The electric tool according to claim 2, characterized in that: Also includes a first inductor element, and / or a second inductor element; The rectifier bridge is connected to the correction module via the first inductor element; The correction module is connected to the bus capacitor via the second inductor element.

18. The electric tool according to claim 17, characterized in that: The first inductor element includes a first conductive wire and a second conductive wire; Two ends of the first wire are connected to the rectifier bridge and the correction module respectively, and two ends of the second wire are connected to the rectifier bridge and the correction module respectively, and the first wire and the second wire have equivalent mutual inductance or equivalent self-inductance; The second inductor element includes a third wire and a fourth wire; Two ends of the third wire are respectively connected to the correction module and the bus capacitor, two ends of the fourth wire are respectively connected to the correction module and the bus capacitor, and the third wire and the fourth wire have equivalent mutual inductance or equivalent self-inductance.

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