CN111384877B - Electric tool and control method thereof - Google Patents
Electric tool and control method thereof Download PDFInfo
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- CN111384877B CN111384877B CN201811610404.7A CN201811610404A CN111384877B CN 111384877 B CN111384877 B CN 111384877B CN 201811610404 A CN201811610404 A CN 201811610404A CN 111384877 B CN111384877 B CN 111384877B
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- lead angle
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/14—Electronic commutators
- H02P6/16—Circuit arrangements for detecting position
- H02P6/17—Circuit arrangements for detecting position and for generating speed information
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K29/00—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices
- H02K29/06—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices with position sensing devices
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- Control Of Motors That Do Not Use Commutators (AREA)
Abstract
The present invention relates to an electric tool, comprising: the device comprises a brushless motor, a detection module, a control module and a battery pack; the battery pack is used for supplying power to the brushless motor, the detection module and the control module; the detection module is used for detecting the load size of the brushless motor; the control module is used for receiving the load size, acquiring the lead angle of the brushless motor according to the load size and controlling the brushless motor to change the phase according to the lead angle. The electric tool acquires the corresponding lead angle through detecting the operating parameters of the brushless motor, and the control module controls the phase change of the brushless motor according to the acquired lead angle, so that the lead angle adapts to the change of the load, the phase change of the brushless motor is accurate, the electric energy loss caused by the phase change lag is avoided, the efficiency of the brushless motor is improved, and the cruising ability of the power supply is further improved.
Description
Technical Field
The invention relates to the field of control, in particular to an electric tool and a control method thereof.
Background
Brushless motors have windings that, due to their inductance, must lead the back emf by an angle called the lead angle. Generally, a brushless motor adopts a fixed lead angle, when the brushless motor is high-speed, the back electromotive force of the brushless motor is close to the power supply voltage, if the rotating speed is further increased, because a winding cannot absorb enough current, the high-speed operation cannot be maintained, and therefore the fixed lead angle leads the motor to have accurate phase change only in a small range, the phase change is inaccurate when the motor exceeds the range, the invalid power is more, the efficiency in the full power range is not high, and the cruising ability of a power supply pack is not high.
Disclosure of Invention
Therefore, it is necessary to provide an electric tool and a control method thereof for solving the problems of low motor efficiency and low battery pack endurance caused by inaccurate phase change of the motor.
A brushless motor lead angle optimization device comprises a brushless motor, a detection module, a control module and a battery pack;
the battery pack is used for detachably providing electric energy for the brushless motor, the detection module and the control module;
the detection module is used for detecting the load of the brushless motor and transmitting the load to the control module; the control module is used for receiving the load size detected by the detection module and acquiring a corresponding lead angle according to a corresponding relation between a load and a lead angle prestored in the control module, wherein the load at least comprises a first load and a second load, the first load is greater than the second load, and the first lead angle corresponding to the first load is greater than or equal to the second lead angle corresponding to the second load;
the control module is further used for controlling the brushless motor to carry out phase commutation according to the obtained lead angle so as to enable the lead angle to adapt to the change of the load; and calculating corresponding phase advance commutation time according to the lead angle, and controlling the brushless motor to carry out phase advance commutation according to the time.
In one embodiment, the brushless motor comprises a rotor and at least one group of stator windings, the electric tool comprises a position sensor, the position sensor is used for acquiring position information of the rotor and sending the position information to the control module, the control module acquires a corresponding lead angle according to the position information and the load size, calculates corresponding time for phase advance commutation according to the lead angle, and controls the motor to commutate in advance according to the time.
In one embodiment, the load is linearly positively correlated with the lead angle.
In one embodiment, the load comprises any one of a voltage, a current and a rotational speed.
In one embodiment, the brushless motor phase-change control device further comprises a gear adjusting module connected with the control module, the gear adjusting module comprises a plurality of current gears, the current gears correspond to the lead angles in a one-to-one manner, the gear adjusting module receives gear information input by a user and sends the gear information to the control module, and the control module acquires the corresponding lead angles according to the gear information and controls the brushless motor to change phases according to the lead angles.
In one embodiment, the current gear includes at least a first gear and a second gear, the first gear includes a value between a first current value and a second current value, the second gear includes a value between a third current value and a fourth current value, the value range of the first gear is smaller than the value range of the second gear, and the lead angle corresponding to the first gear is smaller than the lead angle corresponding to the second gear.
In one embodiment, the detection module includes a sampling unit and an amplifying unit, one end of the sampling unit is connected to the brushless motor, the other end of the sampling unit is connected to one end of the amplifying unit, the other end of the amplifying unit is connected to the control module, the sampling unit is configured to collect a load of the load module, and the amplifying unit is configured to amplify and transmit the load to the control module.
In one embodiment, the sampling unit comprises a sampling resistor R1;
the amplifying unit comprises a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8 and an operational amplifier U1;
the detection module further comprises an input end A1, the input end A1 comprises a positive terminal and a negative terminal, one end of the sampling resistor R1 is connected with the positive terminal, and the other end of the sampling resistor R1 is connected with the negative terminal;
one end of the resistor R2 is connected to one end of the resistor R1 and the positive terminal, the other end of the resistor R2 is connected to one end of the resistor R3, one end of the resistor R4 and the non-inverting input end of the operational amplifier U1, the other end of the resistor R3 is grounded, and the other end of the resistor R4 is connected to a high level;
the other end of resistance R1 and the negative terminal are connected respectively to the one end of resistance R5, the other end of resistance R5 is connected respectively resistance R6's one end, resistance R7's one end and operational amplifier U1's inverting input end, resistance R6's the other end ground connection, resistance R7's the other end is connected respectively operational amplifier U1's output and resistance R8's one end, resistance R8's the other end is connected the control module.
A method of a power tool, the method comprising:
detecting the load size of the brushless motor;
acquiring a corresponding lead angle according to the load size and a pre-stored corresponding relation table of the load and the lead angle, wherein the load at least comprises a first load and a second load, the first load is greater than the second load, and the first lead angle corresponding to the first load is greater than the second lead angle corresponding to the second load;
and controlling the brushless motor to carry out phase commutation according to the obtained lead angle.
In one embodiment, before the step of obtaining the lead angle corresponding to the load according to the size of the load, the method further includes:
pre-storing a linear relation table of the load and the lead angle;
the obtaining of the lead angle corresponding to the load according to the size of the load comprises:
and acquiring a lead angle corresponding to the load size according to the load size and a linear relation table of the load and the lead angle, wherein the load comprises any one of voltage, current and rotating speed.
According to the electric tool and the control method thereof, the load size of the brushless motor is detected by the detection module, then the lead angle is obtained by the control module according to the load size, and the brushless motor is controlled to carry out phase change according to the obtained lead angle. The current lead angle of the brushless motor can be quickly obtained by prestoring the linear relation between the pre-rotation parameter and the lead angle of the brushless motor in the control module, and the control is convenient. Furthermore, the lead angle is not fixed in the application, the control module can adjust the lead angle according to the change of the load size, so that the lead angle is adaptive to the change of the load, the brushless motor is accurate in phase change, the electric energy loss and the situation that the high-load operation cannot be maintained due to large back electromotive force caused by phase change lag are avoided, and the torque of the motor is reduced.
Drawings
Fig. 1 is a block diagram of a brushless motor lead angle optimization apparatus according to an embodiment of the present application;
fig. 2 is a schematic block diagram of a brushless motor lead angle optimizing device according to another embodiment of the present application;
fig. 3 is a schematic circuit diagram of a sampling module according to an embodiment of the present application;
fig. 4 is a block diagram of a brushless motor lead angle optimizing apparatus according to another embodiment of the present application;
fig. 5 is a flowchart illustrating a brushless motor lead angle optimization method according to an embodiment of the present application.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments accompanying figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, as those skilled in the art will recognize without departing from the spirit and scope of the present invention.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. 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 also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not represent the only embodiments.
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.
Referring to fig. 1, an embodiment of the present application provides an electric tool including a brushless motor 100, a detection module 200, a control module 300, and a battery pack 400. Among them, the battery pack 400 is used to detachably supply power to the brushless motor 100, the detection module 200, and the control module 300. One end of the detection module 200 is connected to the brushless motor 100, and the other end is connected to the control module 300, and is configured to detect a load of the brushless motor 100 and transmit the load to the control module 300. The control module 300 receives the load size detected by the detection module 200, and obtains a corresponding lead angle according to a corresponding relationship between the load size and the lead angle pre-stored in the control module 300. The load at least comprises a first load and a second load, the first load is larger than the second load, and the lead angle corresponding to the first load is larger than or equal to the lead angle corresponding to the second load. The control module 300 controls the brushless motor to perform phase commutation according to the obtained lead angle, so that the lead angle of the brushless motor is adapted to the load change of the motor.
Specifically, in the present embodiment, the load may be any one of a current of the brushless motor, a voltage across the brushless motor, and a rotation speed of the brushless motor. The control module 300 prestores a corresponding relationship between the load and the lead angle. When the control module 300 receives the load size detected by the detection module 200, the control module 300 obtains the lead angle of the brushless motor in the current state according to the load size and the pre-stored corresponding relationship, and controls the brushless motor to perform phase change at the lead angle. It is understood that the above correspondence may be a linear relationship, that is, the load magnitude and the lead angle change linearly, and specifically, the load to small and the lead angle are linearly and positively correlated. The control module 300 may pre-store a relationship between the load size and the lead angle, and when the control module 300 obtains the load size, the load size is substituted into the relationship to obtain the lead angle. The linear relationship may also be a linear relationship table of the load size and the lead angle pre-stored in the control module 300, and after the control module 300 obtains the load size, the corresponding lead angle may be obtained through table lookup. According to the invention, through lead angle control, when the amplitude of the counter electromotive force is small or negative, the phase current of the phase is conducted in advance, so that the counter electromotive force can be counteracted by utilizing the inductive potential of the winding, and the winding can absorb enough current to maintain high-speed operation.
In the electric tool provided by the above embodiment, the detection module is adopted to detect the load size of the brushless motor, and then the control module is used to obtain the lead angle according to the load size and control the brushless motor to perform phase commutation according to the obtained lead angle. The current lead angle of the brushless motor can be quickly obtained by pre-storing the corresponding relation between the pre-rotation parameters and the lead angle of the brushless motor in the control module, and the control is convenient.
Furthermore, the lead angle is not fixed in the application, the control module can adjust the lead angle according to the change of the load size, the lead angle is adaptive to the change of the load, the phase change of the brushless motor is accurate, the electric energy loss caused by the phase change lag is avoided, the efficiency of the brushless motor is improved, and the cruising ability of the power supply is further improved.
In one embodiment, a brushless motor includes at least one set of stator windings, a rotor, and a position sensor coupled to the rotor. The position sensor is used for acquiring position information of the rotor and generating a corresponding position signal. The position sensor is also connected to the control module 300 and transmits the generated position signal to the control module 300. The control module 300 may obtain a corresponding lead angle according to the position information and the load size. Because the lead angle and the commutation time have a positive correlation linear relationship, the time required for commutation in advance can be calculated according to the obtained lead angle. Specifically, the lead angle corresponding to a large load is greater than the lead angle corresponding to a small load, and therefore, the lead time corresponding to a large load is greater than the lead time corresponding to a small load. The control module 300 may determine a time required to be advanced according to the size of the load, and control the brushless motor to perform phase shifting in advance according to the current position signal and the time required to be advanced.
Referring to fig. 2, in one embodiment, the detection module 200 includes a sampling unit 210 and an amplifying unit 220. One end of the sampling unit 210 is connected to the brushless motor 100, the other end is connected to one end of the amplifying unit 220, and the other end of the amplifying unit 220 is connected to the control module 300. The sampling unit 210 is used to collect the load magnitude in the brushless motor 100, specifically, the load may be a load voltage, a load current, a rotation speed, and the like. The amplifying unit 220 is used for amplifying and transmitting the load to the control module 300, so that the control module 300 can reliably detect the current operating parameters of the brushless motor.
Specifically, referring to fig. 3, in the present embodiment, the sampling unit 210 includes a sampling resistor R1. The sampling resistor R1 is used for collecting the load current of the brushless motor. In other embodiments, the sampling unit 210 may also be other elements for acquiring a load voltage or a rotation speed of the brushless motor, which is not limited in this embodiment.
The amplifying unit 220 includes a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, and an operational amplifier U1.
The sampling module 200 further includes an input a1 connected to the load module 100, wherein the input a1 includes a positive terminal and a negative terminal. One end of the sampling resistor R1 is connected with the positive terminal, and the other end is connected with the negative terminal, and is used for collecting the load current of the brushless motor.
One end of the resistor R2 is connected to one end of the resistor R1 and the positive terminal of the input terminal, respectively, and the other end of the resistor R2 is connected to one end of the resistor R3, one end of the resistor R4, and the non-inverting input terminal of the operational amplifier U1, respectively. The other end of the resistor R3 is grounded, and the other end of the resistor R4 is connected to a high level. The other end of the resistor R5 is connected with one end of the resistor R6, one end of the resistor R7 and the inverting input end of the operational amplifier U1 respectively. The other end of the resistor R6 is grounded, the other end of the resistor R7 is connected with the output end of the operational amplifier U1 and one end of the resistor R8, and the other end of the resistor R8 is connected with the control module 300 through the input port A2.
The amplifying unit 220 may further include a capacitor C1, a capacitor C2, and a capacitor C3. One end of the capacitor C1 is connected to one end of the resistor R2, one end of the resistor R3, one end of the resistor R4 and the non-inverting input terminal of the operational amplifier U1, and the other end of the capacitor C1 is connected to one end of the resistor R5, one end of the resistor R6 and the inverting input terminal of the operational amplifier U1. The capacitor C1 can absorb the interference signal at the input terminal a1, so that the interference signal cannot enter the operational amplifier U1, thereby stabilizing the output voltage. The capacitor C2 is connected in parallel to two ends of the resistor R7 to form a filter loop for filtering circuit noise signals. One end of the capacitor C3 is connected to one end of the resistor R8 and the output end a2, and the other end is grounded, so as to form a filter loop with the resistor R8 and filter noise signals at the output end.
By reasonably configuring the resistances of the resistor R2, the resistor R3, the resistor R4, the resistor R5, the resistor R6, the resistor R7, and the resistor R8, the voltage across the sampling resistor R1 can be amplified, so that the voltage across the sampling resistor R1 can be reliably detected by the control module 300 after being amplified by the operational amplifier U1. The current received by the control module 300 is the current flowing through the resistor R8, and the control module 300 may process the received current to obtain the actual load current. The control module 300 pre-stores a linear relationship between the load current and the lead angle, so that the control module 300 can obtain the current lead angle of the brushless motor according to the received current and control the brushless motor to perform commutation at the lead angle.
Above-mentioned brushless motor lead angle optimizing apparatus passes through sampling resistance R1 and gathers brushless motor's load current, control module calculates the lead angle according to load current and the linear relation that prestores, and the control motor carries out the commutation with this lead angle, the system operation is simple, control is convenient, and can be according to brushless motor running state real time control motor commutation, make brushless motor commutation accurate, avoid the electric energy loss that the commutation is inaccurate to bring, brushless motor's efficiency is improved, and then the duration of power is improved.
Referring to fig. 4, in one embodiment, the power tool further includes a gear adjustment module 500 connected to the control module 300. The gear adjustment module 500 includes a plurality of current gears, which correspond one-to-one to lead angles. The gear adjusting module 500 receives gear information input by a user and sends the gear information to the control module 300, and the control module 300 acquires a corresponding advance according to the gear information and controls the brushless motor to change phases according to the advance.
Specifically, the current gear includes at least a first gear and a second gear, the first gear includes a value between a first current value and a second current value, and the second gear includes a gear between a third current value and a fourth current value. The numerical range of the first gear is smaller than the numerical range of the second gear, and the lead angle corresponding to the first gear is smaller than the lead angle corresponding to the second gear. The user may select a gear on the gear adjustment module 500 based on the desired advance angle. For example, the current values in first gear range are between I1-I2, and the current values in second gear range are between I3-I4. Wherein I1 is less than I2, I2 is less than I3, and I3 is less than I4. When the user-selected current gear is between I1-I2, the control module 300 receives the gear information and calculates the corresponding lead angle to be theta 1, and when the user-selected current gear is between I3-I4, the control module 300 receives the gear information and calculates the corresponding lead angle to be theta 2. Accordingly, the value of the lead angle θ 1 is smaller than the value of the lead angle θ 2, i.e., a smaller load corresponds to a smaller lead angle.
According to the brushless motor lead angle optimizing device, the gear shifting module is arranged, so that a user can conveniently select a required gear, and a preset lead angle is obtained. Different gears correspond to different loads, the larger the load is, the larger the corresponding lead angle is, and the user can conveniently control the gear. Meanwhile, the control module can adjust the lead angle according to the gear information, the phase change is accurate, the electric energy loss caused by the phase change lag is avoided, the efficiency of the brushless motor is improved, and the cruising ability of the power supply is further improved. Referring to fig. 5, another embodiment of the present application provides a method for controlling an electric tool, including the following steps:
s100: and detecting the load of the brushless motor.
Specifically, the load of the brushless motor is collected by the detection module in this embodiment. Wherein the load includes any one of a load voltage, a load current, and a rotation speed of the brushless motor.
S200: and acquiring a lead angle corresponding to the load according to the load size and the pre-stored corresponding relationship between the load and the lead angle.
In this embodiment, the load magnitude and the lead angle may be in a linear relationship, and the linear relationship may be a functional relation between the load magnitude and the lead angle, or may be a linear relation table between the load magnitude and the lead angle. The load at least comprises a first load and a second load, the first load is larger than the second load, and a first lead angle corresponding to the first load is larger than a second lead angle corresponding to the second load.
And the control module receives the load size, processes the data and then obtains the lead angle corresponding to the current load according to the processed load and the linear relation between the load size and the lead angle. In the present embodiment, the load includes any one of a load voltage, a load current, and a rotation speed of the brushless motor, and the larger the load is, the larger the corresponding lead angle is.
And S300, controlling the brushless motor to carry out phase change according to the obtained lead angle.
And after the control module acquires the lead angle corresponding to the current load, the brushless motor is controlled to carry out phase change according to the lead angle, so that the brushless motor is accurate in phase change.
The method of the electric tool provided by the above embodiment detects the load of the brushless motor, and then calculates the lead angle according to the load by using the control module and controls the brushless motor to perform phase change according to the calculated lead angle. The current lead angle of the brushless motor can be quickly obtained by prestoring the linear relation between the load size of the brushless motor and the lead angle in the control module, and the control is convenient. Furthermore, the lead angle of the brushless motor is not fixed, and can be changed according to the load of the brushless motor, so that the lead angle is adaptive to the load change, the phase change of the brushless motor is accurate, the electric energy loss caused by the phase change lag is avoided, the efficiency of the brushless motor is improved, and the cruising ability of the power supply is further improved.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. An electric power tool, characterized by comprising: the device comprises a brushless motor, a detection module, a control module and a battery pack;
the brushless motor comprises at least one group of stator windings, a rotor and a position sensor connected with the rotor, wherein the position sensor is used for acquiring the position of the rotor, generating a position signal and sending the position signal to the control module;
the battery pack is used for detachably providing electric energy for the brushless motor, the detection module and the control module;
the detection module is used for detecting the load of the brushless motor and transmitting the load to the control module; the control module is used for receiving the load size detected by the detection module and acquiring a corresponding lead angle according to a corresponding relation between a load and a lead angle prestored in the control module, wherein the load at least comprises a first load and a second load, the first load is greater than the second load, and the first lead angle corresponding to the first load is greater than or equal to the second lead angle corresponding to the second load;
and the control module calculates corresponding phase advance commutation time according to the corresponding lead angle and the position signal, and controls the brushless motor to carry out phase advance commutation according to the corresponding phase advance commutation time so as to enable the lead angle to adapt to the change of the load.
2. The power tool of claim 1, wherein the load is linearly positively correlated with the lead angle.
3. The power tool according to any one of claims 1-2, wherein the load includes any one of voltage, current, and rotational speed.
4. The electric tool according to claim 1, further comprising a gear adjustment module connected to the control module, wherein the gear adjustment module includes a plurality of current gears, the current gears correspond to the lead angles one by one, the gear adjustment module receives gear information input by a user and sends the gear information to the control module, and the control module obtains corresponding lead angles according to the gear information and controls the brushless motor to change phases according to the lead angles.
5. The power tool according to claim 4, wherein the current gear positions include at least a first gear position and a second gear position, the first gear position includes a value between a first current value and a second current value, the second gear position includes a value between a third current value and a fourth current value, wherein a range of values of the first gear position is smaller than a range of values of the second gear position, and a lead angle corresponding to the first gear position is smaller than a lead angle corresponding to the second gear position.
6. The power tool of claim 1, wherein the detection module comprises a sampling unit and an amplifying unit, one end of the sampling unit is connected with the brushless motor, the other end of the sampling unit is connected with one end of the amplifying unit, the other end of the amplifying unit is connected with the control module, the sampling unit is used for collecting the load of the load module, and the amplifying unit is used for amplifying and transmitting the load to the control module.
7. The power tool of claim 6, wherein the sampling unit includes a sampling resistor R1;
the amplifying unit comprises a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8 and an operational amplifier U1;
the detection module further comprises an input end A1, the input end A1 comprises a positive electrode terminal and a negative electrode terminal, one end of the sampling resistor R1 is connected with the positive electrode terminal, and the other end of the sampling resistor R1 is connected with the negative electrode terminal;
one end of the resistor R2 is connected to one end of the resistor R1 and the positive terminal, the other end of the resistor R2 is connected to one end of the resistor R3, one end of the resistor R4 and the non-inverting input end of the operational amplifier U1, the other end of the resistor R3 is grounded, and the other end of the resistor R4 is connected to a high level;
the other end of resistance R1 and the negative terminal are connected respectively to the one end of resistance R5, the other end of resistance R5 is connected respectively resistance R6's one end, resistance R7's one end and operational amplifier U1's inverting input end, resistance R6's the other end ground connection, resistance R7's the other end is connected respectively operational amplifier U1's output and resistance R8's one end, resistance R8's the other end is connected the control module.
8. A method of controlling a power tool, the method comprising:
detecting the load size of the brushless motor;
detecting a rotor position of the brushless motor;
acquiring a corresponding lead angle according to the load size and a pre-stored corresponding relation between the load and the lead angle, wherein the load at least comprises a first load and a second load, the first load is greater than the second load, and the first lead angle corresponding to the first load is greater than the second lead angle corresponding to the second load;
and calculating the phase-change time in advance according to the obtained advance angle and the rotor position, and controlling the brushless motor to carry out phase change.
9. The method of claim 8, wherein the load comprises any one of a voltage, a current, and a rotational speed.
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| CN113063998B (en) | 2021-03-09 | 2024-03-15 | 格力博(江苏)股份有限公司 | Electric tool, electric tool load state detection circuit and detection method |
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| CN101325392A (en) * | 2007-06-14 | 2008-12-17 | 台达电子工业股份有限公司 | Device and method for controlling brushless motor |
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| CN101865124B (en) * | 2010-06-18 | 2013-03-20 | 浙江工业大学 | Control method capable of improving COP value of direct current variable-frequency compressor |
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