Motor zero-crossing detection device, driving assembly and electric tool
阅读说明：本技术 电机过零检测装置、驱动组件及电动工具 (Motor zero-crossing detection device, driving assembly and electric tool ) 是由 丛凤龙 张文荣 包旭鹤 于 2021-08-20 设计创作，主要内容包括：本公开涉及一种电机过零检测装置、驱动组件及电动工具,所述装置包括：第一电压检测模块,用于检测所述电机的母线电压；第二电压检测模块,包括检测电阻单元及分压电阻单元,电机的各相定子绕组均通过所述检测电阻单元连接到连接点,连接点连接到所述分压电阻单元,分压电阻单元用于输出反电动势检测电压；控制模块,连接于第一电压检测模块及第二电压检测模块,用于根据母线电压及所述反电动势检测电压进行反电动势过零检测,得到过零检测结果。本公开实施例通过检测所述电机的母线电压及反电动势检测电压,进行反电动势过零检测,可以得到准确的过零检测结果,以提高电机控制的准确性、高效性,使得电机运行更加平顺。(The present disclosure relates to a motor zero-crossing detection device, a driving assembly and an electric tool, the device includes: the first voltage detection module is used for detecting the bus voltage of the motor; the second voltage detection module comprises a detection resistance unit and a voltage division resistance unit, each phase of stator winding of the motor is connected to a connection point through the detection resistance unit, the connection point is connected to the voltage division resistance unit, and the voltage division resistance unit is used for outputting back electromotive force detection voltage; and the control module is connected with the first voltage detection module and the second voltage detection module and used for carrying out back electromotive force zero-crossing detection according to the bus voltage and the back electromotive force detection voltage to obtain a zero-crossing detection result. According to the embodiment of the disclosure, the bus voltage and the back electromotive force detection voltage of the motor are detected to perform back electromotive force zero-crossing detection, so that an accurate zero-crossing detection result can be obtained, the accuracy and the efficiency of motor control are improved, and the motor runs smoothly.)
1. A motor zero-crossing detection apparatus, the apparatus comprising:
the first voltage detection module is used for detecting the bus voltage of the motor;
the second voltage detection module comprises a detection resistance unit and a voltage division resistance unit, each phase of stator winding of the motor is connected to a connection point through the detection resistance unit, the connection point is connected to the voltage division resistance unit, and the voltage division resistance unit is used for outputting back electromotive force detection voltage;
and the control module is connected with the first voltage detection module and the second voltage detection module and used for carrying out back electromotive force zero-crossing detection according to the bus voltage and the back electromotive force detection voltage to obtain a zero-crossing detection result.
2. The apparatus of claim 1, wherein the first voltage detection module comprises a first bus voltage detection resistor, a second bus voltage detection resistor, a third bus voltage detection resistor, a bus voltage detection capacitor, wherein,
a first end of the first bus voltage detection resistor is connected to a bus of the motor, a second end of the first bus voltage detection resistor is connected to a first end of the second bus voltage detection resistor and a first end of the third bus voltage detection resistor,
the second end of the second bus voltage detection resistor is connected to the first end of the bus voltage detection capacitor and grounded;
and the second end of the third bus voltage detection resistor is connected to the second end of the bus voltage detection capacitor and the control module.
3. The apparatus of claim 1, wherein the motor comprises a first phase stator winding, a second phase stator winding, a third phase stator winding, the detection resistance unit comprises a first detection resistance, a second detection resistance, a third detection resistance, and the voltage dividing resistance unit comprises a first voltage dividing resistance and a second voltage dividing resistance, wherein,
the first end of the first detection resistor is connected with a first-phase stator winding of the motor, the first end of the second detection resistor is connected with a second-phase stator winding of the motor, the first end of the third detection resistor is connected with a third-phase stator winding of the motor,
the second end of the first detection resistor, the second end of the second detection resistor and the second end of the third detection resistor are all connected to the first end of the first voltage dividing resistor,
the second end of the first voltage-dividing resistor is connected with the first end of the second voltage-dividing resistor and the control module,
and the second end of the second voltage-dividing resistor is grounded.
4. The apparatus of claim 1, wherein the control module is further configured to:
determining a back EMF zero crossing when the back EMF detected voltage reaches half the bus voltage.
5. The apparatus of claim 1 or 4, wherein the control module is further configured to:
determining a back emf zero crossing when the back emf detect voltage drops to the bus voltage; or
Determining a back emf zero crossing when the back emf detect voltage rises to the bus voltage.
6. The apparatus of claim 1, wherein the control module is further configured to:
when detecting that the counter electromotive force passes through zero, determining a phase change position;
and carrying out commutation control on the motor according to the determined commutation position.
7. The apparatus of claim 1, wherein the motor is a three-phase dc brushless motor.
8. A drive assembly, characterized in that it comprises a motor zero-crossing detection device according to any one of claims 1-7.
9. A power tool comprising the drive assembly of claim 8.
Technical Field
The disclosure relates to the technical field of motor control, in particular to a motor zero-crossing detection device, a driving assembly and an electric tool.
Background
The dc motor has a good speed-adjusting performance, a wide speed-adjusting range and a simple speed-adjusting mode, and is widely applied to a high-performance speed-adjusting system. However, the commutator of the brush motor has the inevitable disadvantages of commutation spark, mechanical noise, poor maintainability, etc. To overcome these disadvantages of the brush DC Motor, a BrushLess DC Motor (BLDC) is used. The brushless DC motor not only makes up the deficiency of the brush DC motor, but also can be compared with the brush DC motor completely in performance, so the brushless DC motor is more and more applied to the fields of high-performance servo, household appliances and the like.
Generally, brushless dc motors have three position sensors fixed on a stator for detecting the magnetic pole positions of a rotor relative to the stator, however, the installation of the position sensors adds extra cost and volume, and is affected by ambient temperature and humidity, so the control method without position sensors (SensorLess) is gaining more and more attention. For the control of the brushless dc motor without a position sensor, a back electromotive force detection method is usually adopted to control the brushless dc motor without a position sensor, and the zero crossing point is generally determined by capturing three opposite electromotive forces in the current control without a position sensor at a high speed.
Disclosure of Invention
According to an aspect of the present disclosure, there is provided a motor zero-cross detection apparatus, the apparatus including:
the first voltage detection module is used for detecting the bus voltage of the motor;
the second voltage detection module comprises a detection resistance unit and a voltage division resistance unit, each phase of stator winding of the motor is connected to a connection point through the detection resistance unit, the connection point is connected to the voltage division resistance unit, and the voltage division resistance unit is used for outputting back electromotive force detection voltage;
and the control module is connected with the first voltage detection module and the second voltage detection module and used for carrying out back electromotive force zero-crossing detection according to the bus voltage and the back electromotive force detection voltage to obtain a zero-crossing detection result.
In one possible embodiment, the first voltage detection module comprises a first bus voltage detection resistor, a second bus voltage detection resistor, a third bus voltage detection resistor, and a bus voltage detection capacitor, wherein,
a first end of the first bus voltage detection resistor is connected to a bus of the motor, a second end of the first bus voltage detection resistor is connected to a first end of the second bus voltage detection resistor and a first end of the third bus voltage detection resistor,
the second end of the second bus voltage detection resistor is connected to the first end of the bus voltage detection capacitor and grounded;
and the second end of the third bus voltage detection resistor is connected to the second end of the bus voltage detection capacitor and the control module.
In one possible embodiment, the motor includes a first phase stator winding, a second phase stator winding, and a third phase stator winding, the detection resistor unit includes a first detection resistor, a second detection resistor, and a third detection resistor, and the voltage dividing resistor unit includes a first voltage dividing resistor and a second voltage dividing resistor, wherein,
the first end of the first detection resistor is connected with a first-phase stator winding of the motor, the first end of the second detection resistor is connected with a second-phase stator winding of the motor, the first end of the third detection resistor is connected with a third-phase stator winding of the motor,
the second end of the first detection resistor, the second end of the second detection resistor and the second end of the third detection resistor are all connected to the first end of the first voltage dividing resistor,
the second end of the first voltage-dividing resistor is connected with the first end of the second voltage-dividing resistor and the control module,
and the second end of the second voltage-dividing resistor is grounded.
In one possible embodiment, the control module is further configured to:
determining a back EMF zero crossing when the back EMF detected voltage reaches half the bus voltage.
In one possible embodiment, the control module is further configured to:
determining a back emf zero crossing when the back emf detect voltage drops to the bus voltage; or
Determining a back emf zero crossing when the back emf detect voltage rises to the bus voltage.
In one possible embodiment, the control module is further configured to:
when detecting that the counter electromotive force passes through zero, determining a phase change position;
and carrying out commutation control on the motor according to the determined commutation position.
In one possible embodiment, the motor is a three-phase dc brushless motor.
According to an aspect of the present disclosure, there is provided a driving assembly including the motor zero-crossing detecting apparatus.
According to an aspect of the present disclosure, there is provided a power tool including the drive assembly of claim 8.
According to the embodiment of the disclosure, the bus voltage of the motor is detected through the first voltage detection module, the accurate back electromotive force detection voltage is detected through the detection resistance unit and the divider resistance unit of the second voltage detection module, and the back electromotive force zero-crossing detection is performed through the control module according to the bus voltage and the back electromotive force detection voltage, so that an accurate zero-crossing detection result can be obtained, the accuracy and the efficiency of motor control are improved, and the motor runs smoothly.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. Other features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the disclosure.
Fig. 1 shows a block diagram of a motor zero-crossing detection apparatus according to an embodiment of the present disclosure.
Fig. 2 shows a block diagram of a motor zero-crossing detection apparatus according to an embodiment of the present disclosure.
Fig. 3a and 3b show schematic diagrams of a two-port network for calculating back emf.
Detailed Description
Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
In the description of the present disclosure, it is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, as used herein, refer to an orientation or positional relationship indicated in the drawings, which is solely for the purpose of facilitating the description and simplifying the description, and does not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and, therefore, should not be taken as limiting the present disclosure.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present disclosure, "a plurality" means two or more unless specifically limited otherwise.
In the present disclosure, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integral; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present disclosure can be understood by those of ordinary skill in the art as appropriate.
The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
The term "and/or" herein is merely an association describing an associated object, meaning that three relationships may exist, e.g., a and/or B, may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the term "at least one" herein means any one of a plurality or any combination of at least two of a plurality, for example, including at least one of A, B, C, and may mean including any one or more elements selected from the group consisting of A, B and C.
Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present disclosure. It will be understood by those skilled in the art that the present disclosure may be practiced without some of these specific details. In some instances, methods, means, elements and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present disclosure.
In the related technology, generally, three-phase back electromotive force is divided, then voltage values after the voltage division of each phase are respectively collected, and a zero crossing point of the back electromotive force is judged through calculation, so that a phase change point is judged. However, for some cases, for example, for an MCU that cannot change the sequence of the ADC sampling channels, if the non-conducting phase is at the last path of the ADC sampling channel, when the duty ratio is small, the accurate value of the non-conducting opposite potential cannot be adopted, which further affects the judgment of the zero crossing point and the commutation point, resulting in the abnormal operation of the motor.
According to the embodiment of the disclosure, the bus voltage of the motor is detected through the first voltage detection module, the accurate back electromotive force detection voltage is detected through the detection resistance unit and the divider resistance unit of the second voltage detection module, and the back electromotive force zero-crossing detection is performed through the control module according to the bus voltage and the back electromotive force detection voltage, so that an accurate zero-crossing detection result can be obtained, the accuracy and the efficiency of motor control are improved, and the motor runs smoothly.
Referring to fig. 1, fig. 1 shows a block diagram of a motor zero-crossing detection apparatus according to an embodiment of the present disclosure.
As shown in fig. 1, the apparatus includes:
a first voltage detection module 20, configured to detect a bus voltage of the motor 10;
the second voltage detection module 30 includes a detection resistance unit 310 and a voltage dividing resistance unit 320, each phase of stator winding of the motor is connected to a connection point through the detection resistance unit 310, the connection point is connected to the voltage dividing resistance unit 320, and the voltage dividing resistance unit 320 is configured to output a back electromotive force detection voltage;
and the control module 40 is connected to the first voltage detection module 20 and the second voltage detection module 30, and configured to perform back electromotive force zero-crossing detection according to the bus voltage and the back electromotive force detection voltage to obtain a zero-crossing detection result.
The first voltage detection module 20, the detection resistance unit 310, the voltage dividing resistance unit 320, and the control module 40 in the embodiment of the present disclosure may have a plurality of possible implementation manners, which are not limited in the embodiment of the present disclosure, and the following describes exemplary implementation manners of the respective modules and units. It should be noted that each module and unit in the embodiments of the present disclosure may be implemented by a hardware circuit, or implemented by using a general hardware circuit in combination with related existing logic.
Referring to fig. 2, fig. 2 is a block diagram of a motor zero-crossing detection apparatus according to an embodiment of the present disclosure.
In one possible implementation, as shown in fig. 2, the motor 10 of the disclosed embodiment may be a three-phase motor, and the motor 10 may be driven by ac power provided by a three-phase full-bridge inverter.
First, a possible implementation of the three-phase full-bridge inverter 50 is exemplarily described, and it should be noted that the implementation of the present disclosure is not limited to the possible implementation of the three-phase full-bridge inverter 50, and in other embodiments, the three-phase full-bridge inverter 50 may have other implementations.
As shown in fig. 2, the three-phase full-bridge inverter 50 may include a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a fifth transistor Q5, a sixth transistor Q6, the first transistor Q1 and the fourth transistor Q4 constitute a first leg and the fourth transistor Q4 is a lower half bridge, the second transistor Q2 and the fifth transistor Q5 constitute a second leg and the fifth transistor Q5 is a lower half bridge, the third transistor Q3 and the sixth transistor Q6 constitute a third bridge arm and the sixth transistor Q6 is a lower half bridge, one end of each winding of the motor 10 is electrically connected, and the other end of each winding is electrically connected between the first transistor Q1 and the fourth transistor Q4, between the second transistor Q2 and the fifth transistor Q5, and between the third transistor Q3 and the sixth transistor Q6.
In one possible implementation, the first Transistor Q1, the second Transistor Q2, the third Transistor Q3, the fourth Transistor Q4, the fifth Transistor Q5, and the sixth Transistor Q6 may be Metal-Oxide-Semiconductor Field-Effect transistors (MOSFETs), Insulated Gate Bipolar Transistors (IGBTs), wherein the transistors may be implemented based on SiC, GaN to improve performance.
In a possible implementation manner, as shown in fig. 2, the three-phase full-bridge inverter 50 may further include a plurality of first input resistors, a plurality of second input resistors, and a plurality of input capacitors for filtering the input signals, and each stator winding of the motor includes a first-phase stator winding a, a second-phase stator winding B, and a third-phase stator winding C, wherein a gate of each transistor of the three-phase full-bridge inverter 50 is electrically connected to the second end of the first input resistor, the first end of the second input resistor, and the first end of the input capacitor, a source of each transistor of the three-phase full-bridge inverter 50 is electrically connected to the second end of the input capacitor, the second end of the second input resistor, and the first end of the first input resistor is used for inputting the control signal,
wherein the drain of the first transistor Q1, the drain of the second transistor Q2, and the drain of the third transistor Q3 are electrically connected, the source of the fourth transistor Q4, the source of the fifth transistor Q5, and the source of the sixth transistor Q6 are electrically connected,
the source of the first transistor Q1 is electrically connected to the drain of the fourth transistor Q4 and the first end of the first phase stator winding, the source of the second transistor Q2 is electrically connected to the drain of the fifth transistor Q5 and the first end of the second phase stator winding, the source of the third transistor Q3 is electrically connected to the drain of the sixth transistor Q6 and the first end of the third phase stator winding,
the second end of the first phase stator winding A, the second end of the second phase stator winding B and the second end of the third phase stator winding C are grounded.
In one example, as shown in fig. 2, the first input resistor may include a first resistor R1, a third resistor R3, a fifth resistor R5, a seventh resistor R7, a ninth resistor R9 and an eleventh resistor R11, the second input resistor may include a second resistor R2, a fourth resistor R4, a sixth resistor R6, an eighth resistor R8, a tenth resistor R10 and a twelfth resistor R12, and the input capacitor may include a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5 and a sixth capacitor C6.
In one example, the three-phase full-bridge inverter 50 may further include a plurality of freewheeling diodes disposed between the source and drain of each transistor for providing a freewheeling path when the transistor is turned off to prevent the transistor from being damaged.
In one possible implementation, the motor 10 may be a three-phase dc brushless motor.
In one example, the embodiment of the present disclosure realizes a Y connection (or may be referred to as a star connection) of the motor 10 by electrically connecting one end of each winding of the stator and electrically connecting the other end of each winding between the first transistor Q1 and the fourth transistor Q4, between the second transistor Q2 and the fifth transistor Q5, and between the third transistor Q3 and the sixth transistor Q6.
In one example, as shown in fig. 2, the motor 10 may include a first phase stator winding a, a second phase stator winding B and a third phase stator winding C, wherein one end of the first phase stator winding a is electrically connected between the first transistor Q1 and the fourth transistor Q4, one end of the second phase stator winding B is electrically connected between the second transistor Q2 and the fifth transistor Q5, and one end of the third phase stator winding C is electrically connected between the third transistor Q3 and the sixth transistor Q6.
In one example, as shown in fig. 2, the first voltage detection module 20 of the embodiment of the present disclosure may be connected to the drain of the first transistor Q1, the drain of the second transistor Q2, and the drain of the third transistor Q3 to collect the bus voltage of the motor.
In one possible implementation, as shown in fig. 2, the first voltage detection module 20 may include a first bus voltage detection resistor Rm1, a second bus voltage detection resistor Rm2, a third bus voltage detection resistor Rm3, and a bus voltage detection capacitor Cm1, wherein,
a first end of the first bus voltage detection resistor Rm1 is connected to a bus (the drain of the first transistor Q1, the drain of the second transistor Q2, and the drain of the third transistor Q3) of the motor 10, a second end of the first bus voltage detection resistor Rm1 is connected to a first end of the second bus voltage detection resistor Rm2 and a first end of the third bus voltage detection resistor Rm3,
a second end of the second bus voltage detection resistor Rm2 is connected to a first end of the bus voltage detection capacitor Cm1 and grounded;
a second terminal of the third bus voltage sensing resistor Rm3 is connected to a second terminal of the bus voltage sensing capacitor Cm1 and the control module 40.
Through the above first voltage detection module 20, the embodiment of the present disclosure can quickly acquire an accurate bus voltage.
In one possible implementation, as shown in fig. 2, the detection resistor unit 310 may include a first detection resistor Rn1, a second detection resistor Rn2, and a third detection resistor Rn3, and the voltage dividing resistor unit 320 includes a first voltage dividing resistor Rf1 and a second voltage dividing resistor Rf2, wherein,
a first end of the first detection resistor Rn1 is connected to a first phase stator winding A of the motor, a first end of the second detection resistor Rn2 is connected to a second phase stator winding B of the motor, a first end of the third detection resistor Rn3 is connected to a third phase stator winding C of the motor,
the second end of the first detecting resistor Rn1, the second end of the second detecting resistor Rn2, and the second end of the third detecting resistor Rn3 are all connected to the first end of the first dividing resistor Rf1,
a second end of the first voltage-dividing resistor Rf1 is connected to a first end of the second voltage-dividing resistor Rf2 and the control module 40,
a second terminal of the second voltage-dividing resistor Rf2 is grounded.
Through the second voltage detection module 30, the embodiment of the present disclosure can realize real-time, fast and accurate collection of back electromotive force.
The principle of collecting the back electromotive force by the second voltage detection module 30 will be described as an example.
In one example, the three-phase stator winding of the motor is respectively connected to the connection point through three resistors, and then the back electromotive force can be obtained after voltage division is performed through the voltage division resistor unit 320, for example, the ABC three-phase voltage and the equivalent resistance of the two-port network to which the three detection resistors are external can be analyzed through thevenin's theorem, and then the voltage magnitude of the back electromotive force can be analyzed.
Referring to fig. 3a and 3b, fig. 3a and 3b are schematic diagrams of two-port networks for calculating back emf.
According to thevenin's theorem, the two-port network shown in fig. 3a can be converted into the two-port network shown in fig. 3B, i.e. a two-port network consisting of a _ PHASE (voltage of the first PHASE stator winding) and B _ PHASE (voltage of the second PHASE stator winding).
Assuming that Rm1 is Rm2 is Rm3, Rab is Rm1 is Rm2/(Rm1+ Rm2) is 1/2 is Rm2, and a _ B is Rm2 is 2+ B _ PHASE (a _ PHASE-B _ PHASE)/(Rm1+ Rm2) is Rm2+ B _ PHASE 1/2(a _ PHASE + B _ PHASE).
The equivalent resistance R of the two-port network outside the phase A, the phase B and the phase C can be obtained in the same wayABCAnd equivalent voltage a _ B _ C:
RABC＝1/2Rm1*Rm3/(1/2Rm2+Rm3)＝1/3Rm3；
A_B_C＝(1/2(A_PHASE+B_PHASE)-C_PHASE)/(1/2Rm2+Rm3)*Rm3+C_PHASE＝1/3(A_PHASE+B_PHASE+C_PHASE)。
accordingly, the required back electromotive voltage BEMFVS can be obtained.
Of course, the above description is exemplary and should not be construed as limiting the embodiments of the disclosure.
In one possible embodiment, the control module 40 may include a component for controlling and operating the electrodes, for example, a zero-crossing detection unit may be included to determine whether to cross zero according to the back electromotive force detection voltage and the bus voltage.
In one possible embodiment, the control module 40 may be further configured to:
determining a back EMF zero crossing when the back EMF detected voltage reaches half the bus voltage.
Through the device, when the back electromotive force detection voltage reaches half of the bus voltage, the back electromotive force zero crossing can be determined, and the accuracy is high.
In one example, the embodiment of the present disclosure may set a threshold range according to half of the bus voltage, such as (U0-Uf, U0+ Uf), where U0 may represent half of the bus voltage and Uf may represent an adjustment value, that is, the present disclosure may also compare the back electromotive force detection voltage with upper and lower limits of the threshold range to determine whether the back electromotive force detection voltage is within the threshold range, and when the back electromotive force detection voltage is within the threshold range, it may be determined that the back electromotive force crosses zero (the motor crosses zero); when the back electromotive force detection voltage is not in the threshold range, the back electromotive force can be determined not to be zero-crossed, so that the flexibility and the adaptability of zero-crossed judgment can be improved.
In one possible embodiment, the control module 40 may be further configured to:
determining a back emf zero crossing when the back emf detect voltage drops to the bus voltage; or
Determining a back emf zero crossing when the back emf detect voltage rises to the bus voltage.
In one example, the back emf detection voltage up to half the bus voltage may have a different form, for example may be distinguished by a difference in a rising edge and a falling edge of a control signal, the back emf zero crossing being determined when the back emf detection voltage falls to the bus voltage (falling edge); or when the back emf detection voltage rises to the bus voltage (rising edge), determining a back emf zero crossing.
In one possible embodiment, the control module 40 may be further configured to:
when detecting that the counter electromotive force passes through zero, determining a phase change position;
and carrying out commutation control on the motor according to the determined commutation position.
In one example, the control module 40 may further include a position determining unit, a commutation control unit, and a commutation control unit, wherein the position determining unit is used for determining a commutation position, for example, by calculating the time of the previous 60 ° sector, calculating the time for delaying the commutation by 30 °, and the commutation control unit is used for performing commutation control on the motor according to the determined commutation position, so that the motor operates normally and stably.
In one example, when six switching devices, namely a first transistor Q1 to a sixth transistor Q6, shown in FIG. 2 are combined (signals of upper and lower half bridges of the same bridge arm are opposite), 8 safe switching states are total, the six safe switching states divide a 360-degree voltage Space into 60-degree sectors and six sectors, and any Vector in 360 degrees can be synthesized by using the six basic effective vectors and two zero quantities.
In one example, the SVPWM adopts a volt-second balance principle, firstly, a sector where a modulation vector voltage is located is judged, and then, a vector voltage required by synthesizing two adjacent vectors in the sector where the vector voltage is located is utilized, so that a stator flux linkage is in a modulation mode of circular rotation. In one example, the driver module generally employs a delta-count timer mode of operation in generating the control signal.
The implementation manner of the control module 40 is not limited in the embodiments of the present disclosure, and can be implemented as needed by those skilled in the art, and for example, the control module 40 may include a processing component, and in one example, the processing component includes but is not limited to a single processor, or a discrete component, or a combination of a processor and a discrete component. The processor may comprise a controller having functionality to execute instructions in an electronic device, which may be implemented in any suitable manner, e.g., by one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), controllers, micro-controllers, microprocessors or other electronic components. Within the processor, the executable instructions may be executed by hardware circuits such as logic gates, switches, Application Specific Integrated Circuits (ASICs), programmable logic controllers, and embedded microcontrollers.
In one possible embodiment, the motor is a three-phase dc brushless motor.
According to an aspect of the present disclosure, there is provided a driving assembly including the motor zero-crossing detecting apparatus.
According to an aspect of the present disclosure, there is provided a power tool including the drive assembly of claim 8.
The electric tool of the disclosed embodiment can include electric drills, electric hair dryers, vehicles (such as electric bicycles, electric vehicles and the like) and other tools, terminals, equipment and the like provided with motors. The terminal may include, for example, a wearable device, a Virtual Reality (VR) device, an Augmented Reality (AR) device, a wireless terminal in Industrial Control (Industrial Control), a wireless terminal in unmanned driving (self driving), a wireless terminal in Remote Surgery (Remote Surgery), a wireless terminal in Smart Grid, a wireless terminal in Transportation Safety (Transportation Safety), a wireless terminal in Smart City (Smart City), a wireless terminal in Smart Home (Smart Home), a wireless terminal in car networking, and the like.
Having described embodiments of the present disclosure, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.