阅读说明：本技术 无刷直流电机双模控制的切换方法及切换系统 (Switching method and switching system for double-mode control of brushless direct current motor ) 是由 张兵兵 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：预设检测周期,设置第一阀值,记录检测周期内三相绕组每相对应的霍尔传感器输出信号的高电平总时间以及低电平总时间；步骤2：逐相计算所述步骤1中获取的高电平总时间与低电平总时间的差值,当差值不等于第一阀值时,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,利用对应的无故障霍尔传感器在下一电周期输出信号的边沿信号,将无刷直流电机切换到无传感器控制状态下运行。采用双模控制切换的方法,避免了传统的停机再切换,增加了运行的顺滑程度,提高了运行效率。(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 detection period, setting a first threshold value, and recording the total high-level time and the total low-level time of output signals of each corresponding Hall sensor of the three-phase winding in the detection period; step 2: calculating the difference value of the total time of the high level and the total time of the low level obtained in the step 1 phase by phase, and when the difference value is not equal to a first threshold value, the corresponding Hall sensor breaks down; and step 3: when one Hall sensor has a fault, the corresponding non-fault Hall sensor is used for outputting the edge signal of the signal in the next electric cycle, and the brushless direct current motor is switched to operate in a non-sensor control state. By adopting the dual-mode control switching method, the traditional shutdown switching is avoided, the smoothness degree of operation is increased, and the operation efficiency is improved.)

1. A switching method for double-mode control of a brushless direct current motor is characterized by comprising the following steps:

step 1: presetting a detection period, setting a first threshold value, and recording the total high-level time and the total low-level time of output signals of each corresponding Hall sensor of the three-phase winding in the detection period;

step 2: calculating the difference value of the total time of the high level and the total time of the low level obtained in the step 1 phase by phase, and when the difference value is not equal to a first threshold value, the corresponding Hall sensor breaks down;

and step 3: when one Hall sensor has a fault, the corresponding non-fault Hall sensor is used for outputting the edge signal of the signal in the next electric cycle, and the brushless direct current motor is switched to operate in a non-sensor control state.

2. The switching method of the dual-mode control of the brushless dc motor according to claim 1, wherein in step 2, when the difference is greater than the first threshold, the corresponding hall sensor has a short-circuit fault; and when the difference value is smaller than the first threshold value, the corresponding Hall sensor has an open-circuit fault.

3. The switching method of the brushless dc motor dual-mode control according to claim 2, wherein the specific method of step 3 is as follows:

when one Hall sensor has a short-circuit fault, the corresponding fault-free Hall sensor is used for outputting a rising edge signal of a signal in the next electrical cycle, and the brushless direct current motor is switched to operate in a sensor-free control state;

when one Hall sensor has an open-circuit fault, the corresponding non-fault Hall sensor outputs a falling edge signal of a signal in the next electrical cycle, and the brushless direct current motor is switched to operate in a non-sensor control state.

4. The switching method of the dual-mode control of the brushless dc motor according to claim 1, wherein the detection period in step 1 has a value ranging from 12ms to 60 ms.

5. The switching method of the dual-mode control of the brushless dc motor according to claim 1, wherein the first threshold value in step 1 is set to a value ranging from 4ms to 10 ms.

6. The switching method of the dual-mode control of the brushless direct current motor according to any one of claims 1 to 5, wherein when one hall sensor fails, the switching is performed by using the edge signal of the corresponding hall sensor without failure, and the specific correspondence is as follows:

when the phase A of the Hall sensor has a fault, correspondingly selecting the edge signal of the phase C of the Hall sensor to switch the brushless direct current motor to operate in a sensorless control state;

when the phase B of the Hall sensor breaks down, correspondingly selecting the edge signal of the phase A of the Hall sensor to switch the brushless direct current motor to operate in a sensorless control state;

when the phase C of the Hall sensor breaks down, the edge signal of the phase B of the Hall sensor is correspondingly selected to switch the brushless direct current motor to operate in a sensorless control state.

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

the voltage division filtering module is respectively connected with the comparator module and the three-phase stator winding of the motor and is used for carrying out voltage division filtering on the counter electromotive force; the comparator module is respectively connected with the voltage division filtering module and the controller and is used for carrying out level conversion on the data subjected to voltage division filtering; the controller is respectively connected with the comparator module and the driver module and is used for analyzing the processed data and then selecting a motor running mode; the driver module is respectively connected with the controller and the inverter module and is used for selecting a PWM working mode; 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 inverter module is respectively connected with the driver module and the three-phase stator winding of the motor and is used for starting and maintaining the brushless direct current motor to normally operate and controlling the motor operation mode according to an instruction sent by the controller.

Technical Field

The invention relates to the field of brushless direct current motor control. And more particularly, to a switching method and a switching system 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 (namely, the control with a position sensor based on a Hall sensor and the sensorless control based on back electromotive force) belongs to redundant control and is widely applied to brushless direct current motor controllers of electric bicycles, two-wheeled balance vehicles 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. In the current common practice, when a Hall sensor is found to be in fault, the controller is in a stop state, and then sensorless control is switched and 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 Hall sequence analysis, and switches to sensorless control under specific conditions on the basis of diagnosing specific fault information of the Hall sensor, thereby realizing smooth switching.

Disclosure of Invention

The invention provides a switching method and a switching system for double-mode control of a brushless direct current motor, and aims to solve the problem of low switching efficiency of traditional double-mode control under single-phase Hall fault.

The invention provides a switching method for double-mode control of a brushless direct current motor, which comprises the following steps:

step 1: presetting a detection period, setting a first threshold value, and recording the total high-level time and the total low-level time of output signals of each corresponding Hall sensor of the three-phase winding in the detection period;

step 2: calculating the difference value of the total time of the high level and the total time of the low level obtained in the step 1 phase by phase, and when the difference value is not equal to a first threshold value, the corresponding Hall sensor breaks down;

and step 3: when one Hall sensor has a fault, the corresponding non-fault Hall sensor is used for outputting the edge signal of the signal in the next electric cycle, and the brushless direct current motor is switched to operate in a non-sensor control state.

Optionally, in step 2, when the difference is greater than the first threshold, a short-circuit fault occurs in the corresponding hall sensor; and when the difference value is smaller than the first threshold value, the corresponding Hall sensor has an open-circuit fault.

Optionally, the specific method of step 3 is as follows:

when one Hall sensor has a short-circuit fault, the corresponding fault-free Hall sensor is used for outputting a rising edge signal of a signal in the next electrical cycle, and the brushless direct current motor is switched to operate in a sensor-free control state;

when one Hall sensor has an open-circuit fault, the corresponding non-fault Hall sensor outputs a falling edge signal of a signal in the next electrical cycle, and the brushless direct current motor is switched to operate in a non-sensor control state.

Optionally, the value range of the detection period in step 1 is 12ms to 60 ms.

Optionally, a value range of the first threshold in step 1 is 4ms to 10 ms.

Optionally, when one hall sensor fails, switching is performed by using an edge signal of the corresponding hall sensor without failure, where the specific correspondence is as follows:

when the phase A of the Hall sensor has a fault, correspondingly selecting the edge signal of the phase C of the Hall sensor to switch the brushless direct current motor to operate in a sensorless control state;

when the phase B of the Hall sensor breaks down, correspondingly selecting the edge signal of the phase A of the Hall sensor to switch the brushless direct current motor to operate in a sensorless control state;

when the phase C of the Hall sensor breaks down, the edge signal of the phase B of the Hall sensor is correspondingly selected to switch the brushless direct current motor to operate in a sensorless control state.

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

the voltage division filtering module is respectively connected with the comparator module and the three-phase stator winding of the motor and is used for carrying out voltage division filtering on the counter electromotive force; the comparator module is respectively connected with the voltage division filtering module and the controller and is used for carrying out level conversion on the data subjected to voltage division filtering; the controller is respectively connected with the comparator module and the driver module and is used for analyzing the processed data and then selecting a motor running mode; the driver module is respectively connected with the controller and the inverter module and is used for selecting a PWM working mode; 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 inverter module is respectively connected with the driver module and the three-phase stator winding of the motor and is used for starting and maintaining the brushless direct current motor to normally operate and controlling the motor operation mode according to an instruction sent by the controller.

The invention at least comprises the following beneficial effects:

1. according to the invention, the high level time and the low level time are compared in the preset time, so that the fault of a certain phase can be rapidly judged.

2. When a certain phase of the Hall sensor breaks down, the normal phase can be switched to the sensorless control state to operate through the rising edge or the falling edge of the normal phase, the conventional method that the control mode is switched after the traditional machine is stopped is avoided, and the operation efficiency of the motor is improved.

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 flowchart of a switching method and a switching system for dual-mode control of a brushless dc motor according to an embodiment of the present invention;

FIG. 2 is a diagram illustrating Hall switching signals under three exemplary conditions according to an embodiment of the present invention;

FIG. 3 is a circuit diagram of dual mode control according to an embodiment of the present invention.

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. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. 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 switching method and a switching system for double-mode control of a brushless direct current motor, as shown in figure 1, comprising the following steps:

step S1: setting a preset period as a detection period, wherein the value range of the preset period is 12 ms-60 ms, and the value is that the time of the Hall sensor passing through each electric period is about 12 ms-60 ms when the brushless direct current motor runs from 1000r/min at a low speed to 5000r/min at a high speed; setting the value range of the first threshold value to be 4 ms-10 ms, wherein the value is that in each electrical cycle, the electrical angle of the Hall sensor passing through 60 degrees is about 2 ms-10 ms, so as to ensure that whether the Hall sensor breaks down after two continuous electrical angles of 60 degrees can be judged, and meanwhile, the value range of the first threshold value is 4 ms-10 ms as the first threshold value is not more than the time of each electrical cycle; recording the total high-level time and the total low-level time of output signals of each corresponding Hall sensor of the three-phase winding in a detection period;

step S2: the fault detection method specifically comprises the following steps: calculating the difference value of the total time of the high level and the total time of the low level obtained in the step 1 phase by phase, and if the difference value is equal to a first threshold value, the phase Hall sensor is normal; if the difference value is larger than the first threshold value, the phase Hall sensor has short-circuit fault; if the difference value is smaller than the first threshold value, the phase Hall sensor has an open-circuit fault;

step S3: when a certain phase of the Hall sensors has a fault, the corresponding fault-free Hall sensors are used for outputting edge signals of signals in the next electrical cycle, and the brushless direct current motor is switched to operate in a sensor-free control state; the method for switching the operation state specifically comprises the following steps:

when the phase A of the Hall sensor has a short-circuit fault, the rising edge of the phase C of the Hall sensor in the next electrical cycle switches the brushless direct current motor to operate in a sensorless control state;

when the phase A of the Hall sensor has an open-circuit fault, the falling edge of the phase C of the Hall sensor in the next electrical cycle switches the brushless direct current motor to operate in a sensorless control state;

when the phase B of the Hall sensor has short-circuit fault, the rising edge of the phase A of the Hall sensor in the next electrical cycle switches the brushless direct current motor to operate in a sensorless control state;

when the phase B of the Hall sensor has an open-circuit fault, the falling edge of the phase A of the Hall sensor in the next electrical cycle switches the brushless direct current motor to operate in a sensorless control state;

when the phase C of the Hall sensor has short-circuit fault, the rising edge of the phase B of the Hall sensor in the next electrical cycle switches the brushless direct current motor to operate in a sensorless control state;

when the phase C of the Hall sensor has an open-circuit fault, the falling edge of the phase B of the Hall sensor switches the brushless direct current motor to operate in a sensorless control state in the next electrical cycle.

Fig. 2 is a schematic diagram of hall switching signals in three typical states, and details of the present invention are described by taking a failure of a phase a of a hall sensor as an example, specifically as follows:

FIG. 2(a) is a schematic diagram of switching values of a Hall sensor phase A, a Hall sensor phase B and a Hall sensor phase C in normal operation in two complete electrical cycles; FIG. 2(B) is a schematic diagram of switching values of a Hall sensor phase A in two complete electrical cycles when a short circuit fault occurs and both a Hall sensor phase B and a Hall sensor phase C are in normal operation; FIG. 2(C) is a schematic diagram of switching values of a Hall sensor phase A in an open circuit fault and a Hall sensor phase B and a Hall sensor phase C in normal operation in two complete electrical cycles;

if the phase A of the Hall sensor has a short-circuit fault, the total high-level time of the phase A of the Hall sensor occupies the range from 0 to 360 degrees in a preset detection period, the total low-level time of the phase A of the Hall sensor is 0, the difference value of the total low-level time of the total high-level time is easily obtained and is larger than a first threshold value, the duration of the first threshold value occupies the range of about 60 degrees, and the rising edge of the phase C of the Hall sensor in a second electrical period switches the brushless direct current motor to operate in a sensorless control state, because in the diagrams shown in the figures 2(a) and 2(b), three continuous states in the electrical angle range from 300 to 480 degrees of the phase A of the Hall sensor are correct, and the rising edge of the phase C of the Hall sensor in the electrical angle of 540 degrees can be used for switching the brushless direct current motor to operate in the sensorless control state; if the phase a of the hall sensor has an open circuit fault, in the range from 0 ° to 360 ° in the preset detection period, the total low level time of the phase a of the hall sensor occupies the range from 0 ° to 360 °, the total high level time is 0, the difference value of the total high level time and the total low level time is greater than a first threshold, the duration of the first threshold occupies the range of about 60 °, and the falling edge of the phase C of the hall sensor in the second electrical period switches the brushless dc motor to operate in the sensorless control state, because in the diagrams shown in fig. 2(a) and fig. 2(C), three states in succession from 480 ° electrical angle to 660 ° electrical angle of the phase a of the hall sensor are correct, and the falling edge of the phase C of the hall sensor at 720 ° electrical angle can be used to switch the brushless dc motor to operate in the sensorless control state.

As shown in fig. 3, the present invention provides a circuit schematic diagram of dual mode control, comprising: a voltage division filtering module 51, a comparator module 52, a controller 53, a driver module 54, an inverter module 55 and a hall processing module 56; a three-phase stator winding of the motor; the concrete description is as follows:

the voltage division filtering module 51 is respectively connected with the comparator module 52 and the three-phase stator winding of the motor and is used for performing voltage division filtering 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 data after voltage division filtering; the controller 53 is respectively connected with the comparator module 52 and the driver module 54, and is used for analyzing the processed data and then selecting a motor operation mode; the driver module 54 is respectively connected with the controller 53 and the inverter module 55, and is used for selecting the PWM operating mode; the inverter module 55 is respectively connected with the driver module 54 and the three-phase stator winding of the motor, and is used for starting and maintaining the brushless direct current motor to normally operate, and controlling the motor operation mode according to an instruction sent by the controller; the Hall processing module is respectively connected with the controller and the three Hall sensors and used for collecting Hall signals in a position sensor control mode, processing the signals and sending the signals to the controller.

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 have been disclosed above, it is not intended to be limited to the uses set forth in the specification and examples. 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.