阅读说明：本技术 直流无刷电机的反电动势过零点检测装置及其方法、应用 (Counter electromotive force zero crossing point detection device of direct current brushless motor and method and application thereof ) 是由 李强 黄小津 李建 刘广民 陶继忠 于 2020-05-14 设计创作，主要内容包括：本发明公开了直流无刷电机的反电动势过零点检测装置及其方法、应用,所述反电动势过零点检测装置包括电机和反电动势过零点检测电路,所述电机的定子上缠绕电机绕组,所述电机绕组一端以星型连接的方式接在一起,另一端从电机引出并连接到驱动器上,还包括发电机绕组,所述发电机绕组与电机绕组缠绕在同一个定子上,且发电机绕组与电机绕组共用一个转子,所述发电机绕组一端以星型连接的方式接在一起,另一端从电机引出并连接在反电动势过零点检测电路上,经过反电动势过零点检测电路后,反电动势过零点信号接入控制芯片。本发明降低了反电动势受干扰和噪声带来的影响,提高了基于反电动势过零点获取电机转子位置方法的可靠性。(The invention discloses a back electromotive force zero crossing point detection device of a direct current brushless motor, a method and application thereof, wherein the back electromotive force zero crossing point detection device comprises a motor and a back electromotive force zero crossing point detection circuit, a motor winding is wound on a stator of the motor, one end of the motor winding is connected together in a star connection mode, the other end of the motor winding is led out from the motor and connected to a driver, the back electromotive force zero crossing point detection device also comprises a generator winding, the generator winding and the motor winding are wound on the same stator, the generator winding and the motor winding share one rotor, one end of the generator winding is connected together in a star connection mode, the other end of the generator winding is led out from the motor and connected to the back electromotive force zero crossing point detection circuit, and a back electromotive force zero crossing. The method reduces the influence of the back electromotive force caused by interference and noise, and improves the reliability of the method for acquiring the position of the motor rotor based on the back electromotive force zero crossing point.)

1. The back electromotive force zero crossing point detection device of the direct current brushless motor comprises a motor and a back electromotive force zero crossing point detection circuit, wherein a motor winding is wound on a stator of the motor, one end of the motor winding is connected together in a star connection mode, the other end of the motor winding is led out from the motor and connected to a driver, the back electromotive force zero crossing point detection device is characterized by further comprising a generator winding, the generator winding and the motor winding are wound on the same stator, the generator winding and the motor winding share one rotor, one end of the generator winding is connected together in a star connection mode, the other end of the generator winding is led out from the motor and connected to the back electromotive force zero crossing point detection circuit, and a back electromotive force zero crossing point signal is connected to a.

2. A back electromotive force zero-crossing detecting apparatus of a brushless dc motor according to claim 1, wherein the generator winding is wound in accordance with a winding manner of the motor winding.

3. A back electromotive force zero-crossing detecting apparatus of a brushless dc motor according to claim 1 or 2, wherein the winding of the generator winding and the motor winding is performed in a manner that:

winding together in parallel, twisting together, wrapping and winding each other or winding inside and outside.

4. A back electromotive force zero-crossing detecting apparatus of a brushless dc motor according to claim 1, wherein a diameter of the generator winding is equal to or smaller than a diameter of the motor winding.

5. The apparatus of claim 1, wherein a photo coupler is provided between the control chip and the back electromotive force zero crossing detecting circuit.

6. The apparatus according to claim 1, wherein the generator winding and the motor winding are both copper wires.

7. A counter-electromotive force zero-crossing detecting apparatus of a brushless dc motor according to claim 1, wherein the motor is a single-phase motor, a two-phase motor, a three-phase motor, or a four-phase motor.

8. A detection method of a back electromotive force zero crossing point detection device of a brushless DC motor according to any one of claims 1 to 7, characterized in that a generator winding and a motor winding are wound on the same stator, one end of the motor winding led out of the motor is connected with a driver, one end of the generator winding led out of the motor is connected with a back electromotive force zero crossing point detection circuit, and after the back electromotive force zero crossing point detection circuit detects the back electromotive force of the generator winding, a back electromotive force zero crossing point signal is connected to a control chip.

9. Use of a back emf zero-crossing detection apparatus of a dc brushless motor according to any of claims 1-7 for position and speed detection of a position sensorless dc brushless motor and for control of a dc brushless motor.

10. Use of a back electromotive force zero-crossing detection apparatus for a brushless dc motor according to any one of claims 1 to 7, wherein the back electromotive force zero-crossing detection apparatus is used for back electromotive force zero-crossing detection of a single-phase motor, a two-phase motor, a three-phase motor, or a four-phase motor.

Technical Field

The invention relates to the technical field of control of a direct current brushless motor, in particular to a device and a method for detecting a zero crossing point of back electromotive force of the direct current brushless motor and application of the device.

Background

The direct current brushless motor replaces the mechanical commutation of the brush motor by an electronic commutation mode. Electronic commutation requires the rotation angle of the motor rotor. The dc brushless motor is generally provided with a position sensor such as a hall sensor or a photoelectric encoder to detect the rotor position. However, in some complex environments, such as vibration, high temperature, humidity and other environmental factors, the position sensor may have faults such as disconnection, loss of pulse signals and the like, thereby causing the operation failure of the motor control system. Therefore, in order to improve the operational reliability of the dc brushless motor, a position sensor-less motor control technique has been widely studied.

A position sensorless dc brushless motor generally estimates a rotor position using physical parameters such as a back electromotive force. The back emf is the induced electromotive force generated by the magnetic induction wire cutting of the motor windings during rotation of the rotor, which is actually a generator effect. The winding of the motor windings on the stator is schematically illustrated in fig. 1. A, B and C form the motor windings, one end of which is connected together in a star connection, the midpoint of the star network is called the neutral point, and the other end is led out from the motor and connected to the driver. In the prior art, a back electromotive force induced by a motor winding is detected by using a simplified hardware circuit schematic diagram shown in fig. 2, and a back electromotive force zero-crossing detection circuit is formed by a low-pass filter circuit, a virtual neutral point circuit and a voltage comparator circuit in fig. 2. The dc brushless motor can be equivalent to a hardware circuit consisting of a resistor, an inductor and a back electromotive force. The three-phase full-bridge inverter circuit drives the motor to work through A, B and C three drive cables connected with the motor. The three drive cables are respectively connected in parallel with three cables and connected with a low-pass filter circuit formed by a resistor and a capacitor. The filtered back electromotive forces Ua, Ub and Uc are connected together in a star-like manner via three resistors of the same resistance, the middle point of the star network being referred to as the virtual neutral point. The voltage comparator circuit can detect the position of the rotor by comparing the virtual neutral point with the magnitude of the back electromotive force on each phase winding to obtain the intersection point of the back electromotive force and the neutral point electromotive force, which is also called as the back electromotive force zero crossing point. The method for obtaining the rotor position by utilizing the back electromotive force has the advantage that the control performance of the sensorless direct current brushless motor is directly influenced by the position estimation accuracy.

Disclosure of Invention

The invention aims to provide a back electromotive force zero crossing point detection device of a direct current brushless motor, which is used for reducing the influence of interference and noise on back electromotive force and improving the reliability of a method for acquiring the position and the speed of a motor rotor based on the back electromotive force zero crossing point.

In addition, the invention also provides a detection method and application of the back electromotive force zero crossing point detection device.

The invention is realized by the following technical scheme:

the back electromotive force zero crossing point detection device of the direct current brushless motor comprises a motor and a back electromotive force zero crossing point detection circuit, wherein a motor winding is wound on a stator of the motor, one end of the motor winding is connected together in a star connection mode, the other end of the motor winding is led out from the motor and connected to a driver, the back electromotive force zero crossing point detection device further comprises a generator winding, the generator winding and the motor winding are wound on the same stator, the generator winding and the motor winding share one rotor, one end of the generator winding is connected together in a star connection mode, the other end of the generator winding is led out from the motor and connected to the back electromotive force zero crossing point detection circuit, and after passing through the back electromotive force zero crossing point detection.

The key points of the invention are as follows: in the original motor structure, a group of winding-generator windings special for measuring the back electromotive force is newly added, and the method for directly measuring the back electromotive force on the motor windings in the prior art is modified into the method for detecting the back electromotive force on the generator windings. Specifically, the method comprises the following steps:

the invention does not detect the counter electromotive force from the cable used for driving the motor any more, in the invention, the generator winding and the motor winding are wound on the same stator, namely the same stator is provided with two groups of windings, one group is still used for driving the motor and is called as the motor winding, the other group is specially used for inducing the counter electromotive force and is called as the generator winding, and the winding of the two groups of cables is schematically shown in figure 3, so that the motor driving cable and the cable for detecting the counter electromotive force are separated. The invention essentially designs the motor and the generator as two independent parts, and the windings of the two parts are simultaneously wound on the same stator structure by the same winding method and share the same rotor. A, B and C in FIG. 3 jointly form a motor winding, A2, B2 and C2 jointly form a generator winding, one end of each of the motor windings A, B and C is connected to a motor driver interface, the other ends of the motor windings A, B and C are connected together in a star connection mode, and the middle point of the star network is still a neutral point. The output ends of the generator windings a2, B2 and C2 are no longer connected with the motor driver interface, but connected with the back electromotive force zero-crossing detection circuit, the other ends are still connected together in a star connection mode, the middle point of the star network becomes a neutral point 2, and a simplified schematic diagram is shown in fig. 4. The generator winding can also be equivalent to a hardware circuit consisting of a resistor, an inductor and a back electromotive force. Due to the arrangement, the motor winding and the generator winding generate back electromotive force in the rotation process of the rotor, the phase and the frequency of the back electromotive force are completely consistent with the trend, and the amplitude of the back electromotive force is changed due to different factors such as the winding number of the winding and the like.

The output end of the generator winding is connected to a hardware circuit after being led out of the motor structure, as shown in fig. 4. The low-pass filter circuit, the virtual neutral point circuit and the voltage comparator circuit in fig. 4 together form a back electromotive force zero-crossing detection circuit. The point of departure from the schematic diagram shown in fig. 2 is that the back emf is no longer drawn from the motor windings, but instead from the generator windings. After passing through the low-pass filter circuit, the back electromotive force is connected together in a star connection mode through three resistors with the same resistance value, and the middle point of the star network becomes a virtual neutral point. The input of the voltage comparator is the electromotive force of the star-type network neutral point and the counter electromotive force after being filtered by the low-pass circuit module. When the back electromotive force is greater than the virtual neutral point electromotive force, the output of the voltage comparator is at a high level, and when the back electromotive force is less than the neutral point electromotive force, the output of the voltage comparator is at a zero level. When the output of the voltage comparator changes from high level to zero level or from zero level to high level, it means that the counter-electromotive force zero-crossing occurs.

The difference between the method of the invention and the prior art method is that the back electromotive force is measured not from the drive cable of the motor, but by the newly added winding. When the device is used for measuring the back electromotive force, the interference on the back electromotive force can be reduced, and the voltage pulse caused by the fly wheel diode is completely eliminated; compared with the prior art, the method has the advantages that the detected interference and noise level of the back electromotive force is reduced, and the signal of the back electromotive force is purer; because the generator winding and the motor winding are on the same stator structure and the respective phases of the windings are completely the same, the counter electromotive force detection method provided by the invention can not cause phase delay of the counter electromotive force.

In conclusion, the method reduces the influence of the back electromotive force caused by interference and noise, and improves the reliability of the method for acquiring the position and the speed of the motor rotor based on the back electromotive force zero crossing point.

Further, the winding mode of the generator winding is consistent with that of the motor winding.

Specifically, the winding direction and the phase are consistent.

Further, the winding mode of the generator winding and the motor winding is as follows:

winding together in parallel, twisting together, wrapping and winding each other or winding inside and outside.

The parallel winding together specifically means that the generator winding and the motor winding are wound side by side synchronously; the winding is twisted together to cross and twist the generator winding and the motor winding into a strand and then the strand is wound on the stator; the mutual wrapping and winding means that the motor winding completely wraps the generator winding or vice versa, the inner and outer winding means that the motor winding is wound at one end close to the outer side of the stator structure, and the generator winding is wound at one end close to the inner side of the stator structure or vice versa, as shown in fig. 3.

Further, the diameter of the generator winding is smaller than or equal to the diameter of the motor winding.

When the back electromotive force is detected as far as possible, the driving capability of the motor is not influenced.

Further, a photoelectric coupler is arranged between the control chip and the back electromotive force zero-crossing detection circuit.

Further, the generator winding and the motor winding are both copper wires.

Further, the motor is a single-phase motor, a two-phase motor, a three-phase motor or a four-phase motor.

A detection method of a back electromotive force zero crossing point detection device based on a direct current brushless motor is characterized in that a generator winding and a motor winding are wound on the same stator, one end of the motor winding, which is led out of the motor, is connected with a driver, one end of the generator winding, which is led out of the motor, is connected with a back electromotive force zero crossing point detection circuit, and the back electromotive force zero crossing point detection circuit detects back electromotive force of the generator winding and then accesses a back electromotive force zero crossing point signal to a control chip.

The back electromotive force zero crossing point detection device is used for detecting the position and the speed of the brushless DC motor without a position sensor and controlling the brushless DC motor.

The back electromotive force zero crossing point detection device is used for detecting the back electromotive force zero crossing points of a single-phase motor, a two-phase motor, a three-phase motor or a four-phase motor.

The stator of the motor is of a 2-pole-pair stator structure, and can also be of a 4-pole-pair, 6-pole and 8-pole-pair stator structure.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. when the counter electromotive force is measured, the counter electromotive force is detected by the newly added generator winding instead of being measured from a driving cable of the motor, so that the interference on the counter electromotive force can be reduced when the counter electromotive force is measured, and the voltage pulse caused by the fly wheel diode is completely eliminated.

2. The interference and noise level of the back electromotive force detected by the invention is reduced, and the signal of the back electromotive force is purer

3. Because the generator winding and the motor winding are on the same stator structure and the respective phases of the windings are completely the same, the counter electromotive force detection method provided by the invention can not cause phase delay of the counter electromotive force.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

fig. 1 is a schematic structural diagram of a conventional motor;

FIG. 2 is a schematic diagram of a conventional back EMF hardware circuit;

FIG. 3 is a schematic structural view of the motor of the present invention;

fig. 4 is a hardware circuit schematic diagram of back electromotive force of embodiment 1;

fig. 5 is a hardware circuit schematic diagram of back electromotive force according to embodiment 2.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not used as limitations of the present invention.