阅读说明：本技术 一种无刷直流电机双模控制的切换方法与装置 (Switching method and device for double-mode control of brushless direct current motor ) 是由 陆腾飞 魏海峰 王浩陈 张懿 于 2019-10-31 设计创作，主要内容包括：本发明公开了一种无刷直流电机双模控制的切换方法,包括：步骤1：预设置预设阀值、检测周期,在一个检测周期内记录三相定子绕组每相产生的反电动势的方波信号的高电平总时间和低电平总时间；步骤2：逐相计算一个检测周期内高电平总时间和低电平总时间差值的绝对值占一个检测周期时间的比值,当比值大于预设阀值时,则该相对应的霍尔传感器发生故障；步骤3：当一个霍尔传感器发生故障时,利用正常相方波信号在下一电周期内的边沿信号进行双模切换；本发明可以直接实现切换、不需要停止电机再切换控制模式。(The invention discloses a switching method for double-mode control of a brushless direct current motor, which comprises the following steps: step 1: presetting a preset threshold value and a detection period, and recording the total high-level time and the total low-level time of square wave signals of counter electromotive force generated by each phase of a three-phase stator winding in one detection period; step 2: calculating the ratio of the absolute value of the difference value between the total high-level time and the total low-level time in one detection period to the time of one detection period phase by phase, and when the ratio is greater than a preset threshold value, the corresponding Hall sensor breaks down; and step 3: when one Hall sensor breaks down, the edge signal of the normal phase square wave signal in the next electrical cycle is used for dual-mode switching; the invention can directly realize switching without stopping the motor and switching the control mode.)

1. A switching method of double-mode control of a brushless direct current motor is characterized in that when a Hall sensor of the brushless direct current motor breaks down, a voltage division filtering module and a comparator module collect back electromotive force signals, a controller is quickly and accurately switched to sensorless control according to processed square wave signals, and smooth switching is achieved; the method comprises the following steps:

step 1: presetting a preset threshold value and a detection period, and recording the total high-level time and the total low-level time of square wave signals of counter electromotive force generated by each phase of a three-phase stator winding in one detection period;

step 2: calculating the ratio of the absolute value of the difference value between the total high-level time and the total low-level time in one detection period to the time of one detection period phase by phase, and when the ratio is greater than a preset threshold value, the corresponding Hall sensor breaks down;

and step 3: when one Hall sensor has a fault, the edge signal of the normal phase square wave signal in the next electrical cycle is used for dual-mode switching.

2. The switching method of the dual-mode control of the brushless DC motor according to claim 1, wherein in the step 1, the detection period is 3 to 5 electrical periods.

3. The switching method of the dual-mode control of the brushless dc motor according to claim 1, wherein in the step 2, the predetermined threshold is 5% to 10%.

4. A switching method of dual-mode control of a brushless dc motor according to any one of claims 1-3, wherein in step 3, when the controller determines that the hall sensor of one phase is out of order, the square wave signals of the other two phases are detected in the next electrical cycle, and when the edge signal of any one of the other two phases is detected, the switching control mode is started, and the smooth switching from the hall sensor based position sensor control to the back emf based sensorless control is completed.

5. The switching method of the dual mode control of the brushless dc motor as claimed in claim 1, wherein the square wave signal of the counter electromotive force generated at each phase of the three-phase stator winding is always detected in a position sensor control mode of the hall sensor and a sensorless control mode based on the counter electromotive force.

6. A device of brushless DC motor dual mode control, characterized by that includes: a voltage division filter module, a comparator module, a controller, a driver module, an inverter module, a Hall processing module, a three-phase stator winding of the brushless DC motor,

the voltage division filtering module is connected with a three-phase stator winding of the brushless direct current motor and is used for carrying out voltage division filtering processing on the counter electromotive force of the three-phase stator winding of the brushless direct current motor;

the comparator module is respectively connected with the voltage division filtering module and the controller and is used for converting the level of the signal subjected to voltage division filtering into a square wave signal and sending the square wave signal to the controller;

the Hall processing module is respectively connected with the controller and the three Hall sensors and is used for acquiring Hall signals in a position sensor control mode, processing the signals and then sending the signals to the controller;

the controller is connected with the driver module, judges the running state of the motor based on the square wave signal output by the comparator module and outputs a control signal to the driver module;

the inverter module is respectively connected with the driver module and a three-phase stator winding of the brushless direct current motor, and the inverter module realizes the normal operation of the brushless direct current motor based on a driving signal of the driver module.

Technical Field

The invention relates to the field of brushless direct current motor control. And more particularly, to a switching method and apparatus for dual mode control of a brushless dc motor.

Background

The brushless DC motor belongs to a kind of permanent magnet synchronous motor, and has the advantages of high efficiency, fast response, low noise, etc. The dual-mode control of the brushless direct current motor, namely, the compatible hall sensor-based control with a position sensor and the back electromotive force-based sensorless control, belongs to the redundancy control, and has wide application in brushless direct current motor controllers of electric bicycles, two-wheeled balance cars and the like.

The main function of the dual-mode control is to switch to back-emf-based sensorless control when the hall sensor fails. How to accurately and quickly switch to sensorless control when a hall sensor fails, particularly for the most common single-phase hall faults. At present, the common method is that when a Hall sensor is found to be in fault, the controller is started to stop, then sensorless control is switched and the controller is restarted. The method has the advantages that the phenomenon that the rotating speed is suddenly reduced and then suddenly increased can occur, the running stability is poor, and the user experience is reduced.

The invention utilizes the counter electromotive force signal converted by the circuit, and when the counter electromotive force signal is abnormal, the control can be more quickly and accurately switched to the sensorless control, thereby realizing smooth switching.

Disclosure of Invention

The invention provides a switching method and a switching device for double-mode control of a brushless direct current motor, which aim to solve the problems of unstable switching and low efficiency of the traditional double-mode control.

The invention provides a switching method of double-mode control of a brushless direct current motor, when a Hall sensor of the brushless direct current motor breaks down, a voltage division filtering module and a comparator module collect back electromotive force signals, a controller is quickly and accurately switched to sensorless control according to processed square wave signals, and smooth switching is realized; the method comprises the following steps:

step 1: presetting a preset threshold value and a detection period, and recording the total high-level time and the total low-level time of square wave signals of counter electromotive force generated by each phase of a three-phase stator winding in one detection period;

step 2: calculating the ratio of the absolute value of the difference value between the total high-level time and the total low-level time in one detection period to the time of one detection period phase by phase, and when the ratio is greater than a preset threshold value, the corresponding Hall sensor breaks down;

and step 3: when one Hall sensor has a fault, the edge signal of the normal phase square wave signal in the next electrical cycle is used for dual-mode switching.

Further, in the step 1, the detection period is 3-5 electrical periods.

Further, in the step 2, the preset threshold value is 5% to 10%.

Further, in step 3, when the controller determines that the hall sensor of one phase has a fault, the controller detects square wave signals of the other two phases in the next electrical cycle, and when edge signals of any one of the other two phases are detected, the controller starts to switch the control mode, and the smooth switching from the hall sensor-based position sensor control to the back electromotive force-based sensorless control is completed.

Further, in the hall sensor with position sensor control mode and the back electromotive force based sensorless control mode, the detection of the square wave signal of the back electromotive force generated for each phase of the three-phase stator winding is always performed.

The invention also provides a device for double-mode control of the brushless direct current motor, which comprises: a voltage division filter module, a comparator module, a controller, a driver module, an inverter module, a Hall processing module, a three-phase stator winding of the brushless DC motor,

the voltage division filtering module is connected with a three-phase stator winding of the brushless direct current motor and is used for carrying out voltage division filtering processing on the counter electromotive force of the three-phase stator winding of the brushless direct current motor;

the comparator module is respectively connected with the voltage division filtering module and the controller and is used for converting the level of the signal subjected to voltage division filtering into a square wave signal and sending the square wave signal to the controller;

the Hall processing module is respectively connected with the controller and the three Hall sensors and is used for acquiring Hall signals in a position sensor control mode, processing the signals and then sending the signals to the controller;

the controller is connected with the driver module, judges the running state of the motor based on the square wave signal output by the comparator module and outputs a control signal to the driver module;

the inverter module is respectively connected with the driver module and a three-phase stator winding of the brushless direct current motor, and the inverter module realizes the normal operation of the brushless direct current motor based on a driving signal of the driver module.

The invention at least comprises the following beneficial effects:

1. the reverse electromotive force signal is detected in real time in a reversing mode in which the three-phase signal of the Hall sensor is used as a switching signal, and whether the reverse electromotive force is abnormal or not is judged to analyze whether the Hall sensor has faults or not, so that the abnormity can be diagnosed more quickly, and the quick switching from the control with the position sensor based on the Hall sensor to the sensorless control based on the reverse electromotive force is realized.

2. Under the condition of Hall sensor failure, a normal level signal of one phase is used as a standard to quickly realize dual-mode switching, so that the problem that the traditional dual-mode control is inefficient in stopping firstly and then switching to sensorless control is effectively solved, and the improvement of the running stability of the motor is facilitated.

Drawings

The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:

fig. 1 is a schematic circuit diagram of a switching device for dual-mode control of a brushless dc motor according to an embodiment of the present invention;

fig. 2 is a flowchart of a switching method of dual-mode control of a brushless dc motor according to an embodiment of the present invention;

FIG. 3 is a diagram illustrating an input terminal test point X of a voltage division filter module in the case of no failure of a Hall sensor according to an embodiment of the present invention₁、X₂、X₃The measured oscillogram of (a);

FIG. 4 shows an input terminal test point X of the voltage-dividing filter module in the case of a failure of the Hall sensor A according to the embodiment of the present invention₁、X₂、X₃The measured oscillogram of (a);

FIG. 5 is a diagram showing an output terminal test point Y of the comparator module in the case of no failure of the Hall sensor according to the embodiment of the present invention₁、Y₂、Y₃The measured oscillogram of (a);

FIG. 6 shows an output terminal test point Y of the comparator module in case of a failure of the Hall sensor A according to the embodiment of the present invention₁、Y₂、Y₃The measured waveform of (2).

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a device for double-mode control of a brushless direct current motor, as shown in figure 1, comprising: a voltage division filtering module 51, a comparator module 52, a controller 53, a hall processing module 54, a driver module 55, an inverter module 56, a three-phase stator winding of the brushless dc motor, wherein:

the voltage division filtering module 51 is connected with a three-phase stator winding of the brushless direct current motor and is used for performing voltage division filtering processing on the counter electromotive force;

the comparator module 52 is respectively connected to the voltage division filtering module 51 and the controller 53, and is configured to perform level conversion on the signal subjected to the voltage division filtering processing to obtain a square wave signal;

the hall processing module 54 is respectively connected with the controller 53, the hall sensor a, the hall sensor B and the hall sensor C, and is used for acquiring hall signals in a position sensor control mode, processing the signals and sending the signals to the controller;

the controller 53 is connected with the driver module 55 and is used for analyzing the square wave signal output by the comparator module, judging the running state of the motor and outputting a driving signal to the driver module;

the inverter module 56 is connected to the driver module 55 and the three-phase stator winding of the brushless dc motor, respectively, for implementing the normal operation of the brushless dc motor according to the driving signal of the driver module.

Test point X₁The input end of the U-phase stator winding is connected with the voltage-dividing filtering module; test point X₂The input end of the V-phase stator winding is connected with the voltage-dividing filtering module; test point X₃And the W-phase stator winding input end is connected with the voltage division filtering module.

Test point Y₁The output end of the U-phase stator winding corresponding to the comparator module is connected; test point Y₂The output end of the comparator module corresponding to the V-phase stator winding is connected; test point Y₃And the output end of the comparator module corresponding to the W-phase stator winding is connected.

The Hall sensor A corresponds to the U-phase stator winding, the Hall sensor B corresponds to the V-phase stator winding, and the Hall sensor C corresponds to the W-phase stator winding.

As shown in fig. 2, a switching method for dual-mode control of a brushless dc motor according to an embodiment of the present invention includes:

step S1: a preset value detection period T is 3-5 electrical periods, and increased errors exist in the statistics of the total high-level time and the total low-level time only in 1-2 electrical periods, particularly in an acceleration and deceleration stage; in order to ensure the detection precision, 3-5 electrical periods are selected in the detection period to effectively avoid errors, and the total high-level time T of square wave signals of counter electromotive force generated by each phase of a three-phase stator winding is recorded in one detection period_AAnd low level total time T_B；

Step S2: calculating the ratio of the absolute value of the time difference of the high level and the low level in one period to the time of the whole period phase by phase, and when the ratio is greater than a preset threshold value, the corresponding Hall sensor breaks down; the ratio calculation formula is as follows:

|T_A-T_B|÷T

the preset threshold value is 5% -10%, so that the fault of the Hall sensor can be quickly diagnosed from the square wave signal of the back electromotive force;

step S3: when one Hall sensor has a fault, the edge signal of the normal phase square wave signal in the next electrical cycle is used for dual-mode switching.

As shown in fig. 3, in which fig. 3(a), 3(b) and 3(c) pass the measurement X when the hall sensor is not faulty₁、X₂、X₃The back electromotive force waveform obtained by three points.

As shown in fig. 4, wherein fig. 4(a), 4(b) and 4(c) are measured by measuring X when the hall sensor a fails₁、X₂、X₃The back electromotive force waveform obtained by three points.

As can be seen from fig. 3 and 4, the brushless dc motor can keep rotating and generate different back electromotive force waveforms when the hall sensors are normal or a single hall sensor fails. According to the principle, the Hall sensor fault corresponding to the fault can be found out by converting the back electromotive force waveform into the square waveform and analyzing the total time of high level and the total time of low level in the square waveform.

As shown in FIG. 5, FIG. 5(a), FIG. 5(b), FIG. 5(c) are graphs obtained by measuring Y when the Hall sensor is not faulty₁、Y₂、Y₃The level waveforms obtained at three points.

As shown in FIG. 6, FIG. 6(a), FIG. 6(b), FIG. 6(c) are diagrams of the Hall sensor A by measuring Y when it is out of order₁、Y₂、Y₃The level waveforms obtained at three points.

In step S3, when the controller determines that the hall sensor of one phase is faulty, the square wave signals of the other two phases are detected in the next electrical cycle, and when the edge signal of any one of the other two phases is detected, the control mode is switched to complete the smooth transition from the hall sensor based position sensor control to the back emf based sensorless control, for example:

as shown in fig. 6, in the back electromotive force square wave signal of the U-phase stator winding in fig. 6(a), the ratio of the absolute value of the time difference between the high level and the low level in the detection period T to the time of the whole period is about 25%, and if the absolute value is greater than the preset threshold, the hall sensor a corresponding to the U-phase stator winding fails; when the next electric period Te detects that a level jump R1 occurs in the counter electromotive force square wave signal of the V-phase stator winding or a level jump R2 occurs in the counter electromotive force square wave signal of the V-phase stator winding, the controller controls the driver to switch the control mode, and the control is switched from the Hall sensor-based position sensor control to the counter electromotive force-based sensorless control.

In a hall sensor position sensor control mode and a back electromotive force-based sensorless control mode, square wave signals of back electromotive force generated by each phase of a three-phase stator winding are always detected, so that the rapidity of fault switching is realized.

It is obvious that those skilled in the art can obtain various effects not directly mentioned according to the respective embodiments without trouble from various structures according to the embodiments of the present invention. While embodiments of the invention/utility model have been disclosed above, it is not limited to the applications listed in the description and the embodiments. It can be applied to all kinds of fields suitable for the present invention. Additional modifications will readily occur to those skilled in the art. It is therefore intended that the invention not be limited to the exact details and illustrations described and illustrated herein, but fall within the scope of the appended claims and equivalents thereof.