CN107508509B - Brushless DC motor control method and device and its low-speed heavy-load control method - Google Patents

Abstract

The invention relates to a control method and device of a brushless DC motor and its low-speed and heavy-load control method. The comparison result of the brushless DC motor is used to control the corresponding power tube to be turned on or off when the Hall signal combination of the brushless DC motor is turned on. The brushless DC motor can still output as much torque as possible for a long time under low-speed and heavy-load conditions, and effectively reduce the switching frequency of the power tube, reduce the heat generation of the control system, and improve the efficiency of power utilization.

Description

Brushless DC motor control method and device and its low-speed heavy-load control method

technical field

The invention relates to the field of electrical control, in particular to a control method and device for a brushless DC motor and a low-speed and heavy-load control method thereof.

Background technique

In recent years, brushless DC motors have been widely used in home appliances, robots, electric vehicles and other fields due to their unique advantages of small size, light weight, high efficiency, large torque, and good speed regulation performance. Under the low-speed and heavy-load conditions of electric vehicles, due to the limitation of power tube performance, the brushless DC motor control system is very easy to enter the over-current protection and cannot work normally, let alone achieve satisfactory control performance. For example, when riding an electric vehicle through mountain roads and bridges with large slopes and long distances, due to the low-speed and heavy-load conditions of the brushless DC motor, the motor often enters over-current protection before reaching the top of the slope, making the The electric car completely loses power, and under the action of gravity, it is very easy to cause the motor to reverse and cause the tragedy of car crash.

How to solve the above problems is an urgent need for manufacturers to solve.

Contents of the invention

The purpose of the present invention is to provide a brushless DC motor control method and device and its low-speed and heavy-load control method to solve the problem that the brushless DC motor control system is easy to enter the over-current protection due to the limitation of the performance of the power tube under low-speed and heavy-load conditions. and not working properly.

In order to achieve the above object, the technical solution adopted in the embodiment of the present invention is as follows:

The invention provides a low-speed and heavy-duty control method for a brushless DC motor, which uses the comparison result of the current given value of the brushless DC motor and the current average value of the brushless DC motor to control the combined opening of the Hall signal of the brushless DC motor The corresponding power tube is turned on or off.

The present invention also provides a brushless DC motor control method. After the brushless DC motor is determined to enter the low-speed and heavy-load working condition, the brushless DC motor is controlled at low speed and heavy load through the above-mentioned brushless DC motor low-speed and heavy-load control method .

The present invention also provides a brushless DC motor control device, which includes a working condition judging module for judging whether the brushless DC motor is in a low-speed and heavy-load working condition;

The processing module is used to control the Hall of the brushless DC motor through the comparison result of the current given value of the brushless DC motor and the current average value of the brushless DC motor after it is determined that the brushless DC motor enters a low-speed and heavy-duty working condition. The power transistor corresponding to the opening of the signal combination is turned on or off.

Compared with the prior art, the beneficial effects of the present invention are as follows:

The invention provides a brushless DC motor control method and device and its low-speed and heavy-load control method, wherein the brushless DC motor low-speed and heavy-load control method uses the current given value of the brushless DC motor and the current average value of the brushless DC motor Compare the results to control the corresponding power tube to be turned on or off when the Hall signal combination of the brushless DC motor is turned on. The brushless DC motor can still output as much torque as possible for a long time under low-speed and heavy-load conditions, and effectively reduce the switching frequency of the power tube, reduce the heat generation of the control system, and improve the efficiency of power utilization.

In order to make the above-mentioned objects, features and advantages of the present invention more comprehensible, preferred embodiments will be described in detail below together with the accompanying drawings.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 shows a flow chart of a low-speed and heavy-load control method for a brushless DC motor provided by an embodiment of the present invention.

FIG. 2 is a flow chart of sub-steps of step S230 shown in FIG. 1 .

FIG. 3 is a flow chart of sub-steps of step S212 shown in FIG. 2 .

Fig. 4 shows a flow chart of a brushless DC motor control method provided by an embodiment of the present invention.

Fig. 5 shows a schematic block diagram of a brushless DC motor control device provided by an embodiment of the present invention.

Fig. 6 shows a schematic block diagram of a working condition determination module of the brushless DC motor control device provided by the embodiment of the present invention.

Fig. 7 shows a schematic block diagram of a processing module of the brushless DC motor control device provided by the embodiment of the present invention.

In the figure: 100-brushless DC motor control device; 110-operating condition determination module; 111-detection submodule; 112-judgment submodule; 120-processing module; 121-first setting submodule; 122-second setting Stator module; 123-comparison sub-module.

Detailed ways

The present invention is described in further detail now in conjunction with accompanying drawing. These drawings are all simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, so they only show the configurations related to the present invention.

The technical solutions of the above-mentioned embodiments of the present invention will be described in detail below using several specific embodiments.

first embodiment

Please refer to FIG. 1 . FIG. 1 shows a flowchart of a low-speed and heavy-load control method for a brushless DC motor provided by an embodiment of the present invention. The method uses the comparison result of the current given value of the brushless DC motor and the current average value of the brushless DC motor to control the opening or closing of the power tube corresponding to the hall signal combination of the brushless DC motor.

The method for obtaining the comparison result includes the following steps:

S210: Set the given current value I _set .

Define the current given value as I _set .

S220: Set the average value I _p of the current.

Define the average value of the rated current of the brushless DC motor as _Ip , and obtain the average current of the brushless DC motor within each 0.1L/R electrical time period from the initial moment of entering the low-speed and heavy-duty working condition I _p ; and the initial value of the current average value I _p is the current value at the initial moment when the brushless DC motor enters the low-speed and heavy-duty working condition, and the value of the current average value I _p is updated every 0.1L/R electrical time cycle.

S230: Comparing the current given value _Iset with the current average value _Ip , if the current given value _Iset is greater than or equal to the current average value _Ip , turn on the corresponding power tube according to the Hall signal combination of the brushless DC motor; If the current given value I _set is smaller than the current average value I _p , all power tubes are turned off.

Compare the current given value I _set with the current average value I _p , if the current given value I _set is greater than or equal to the current average value I _p , then turn on the corresponding power tube according to the Hall signal combination of the brushless DC motor; if the current If the given value I _set is smaller than the current average value I _p , all power tubes will be turned off.

Referring to Fig. 2, step S210 also includes the following steps:

S211: Obtain the average speed S _p of the brushless DC motor within the electrical time period from the initial moment when the brushless DC motor enters the low-speed and heavy-load working condition.

S212: Calculate the current given value I _set according to the average rotational speed S _p .

The given current value I _set is calculated by the brushless DC motor from the average rotational speed S _p of the brushless DC motor within the electrical time period at the initial moment when the brushless DC motor enters the low-speed and heavy-load working condition.

Referring to Fig. 3, step S212 includes the following steps:

S2121: Get the rated working current I _e of the power tube.

Get the rated working current I _e of the power tube from the data.

S2122: Call the rated speed N _e of the brushless DC motor.

Get the rated speed N _e of the brushless DC motor from the data

S2123: Current given value I _set =(-5I _e *S _p /N _e )+I _e , and the initial setting of S _p is 0.1N _e .

Current given value I _set =(-5I _e *S _p /N _e )+I _e , and the initial setting of S _p is 0.1N _e , that is, the values of I _set and S _p are updated every L/R electrical time cycle .

second embodiment

Please refer to FIG. 4 . FIG. 4 shows a flowchart of a method for controlling a brushless DC motor provided by an embodiment of the present invention. In the method, after it is determined that the brushless direct current motor enters a low-speed and heavy-load working condition, the brushless direct-current motor is controlled at low speed and heavy load through the low-speed and heavy-load control method for the brushless direct-current motor provided in the first embodiment.

The method for judging that the brushless DC motor enters the low-speed and heavy-load working condition includes the following steps:

S310: Detect the output voltage V _o of the speed control handle and the speed S of the brushless DC motor.

By detecting the output voltage V _o of the speed control handle and the speed S of the brushless DC motor, it can be obtained whether the brushless DC motor enters the low-speed heavy-duty working condition.

S320: If the duration T _o of the output voltage V _o at the maximum value is not less than 3 s, and the speed S of the brushless DC motor is not greater than 10% of the rated speed _Ne of the brushless DC motor, determine that the brushless DC motor is Enter the low-speed and heavy-load working condition; otherwise, it is determined that the brushless DC motor has not entered the low-speed and heavy-load working condition.

Compare the detected output voltage V _o with the maximum value, when the duration T _o of the maximum value is not less than 3s, compare the speed S with 10% of the rated speed _Ne , so as to ensure that the brushless DC motor is indeed at Under low-speed and heavy-load conditions; otherwise, the brushless DC motor does not enter low-speed and heavy-load conditions.

In the present invention, it is set that the duration of V _o being at the maximum value is not less than 3S, and the speed S of the brushless DC motor is not greater than 10% of the rated speed _Ne of the brushless DC motor. In other embodiments, it can be other value.

third embodiment

Referring to FIG. 5 , an embodiment of the present invention provides a brushless DC motor control device 100 . The brushless DC motor control device 100 includes a working condition determination module 110 and a processing module 120 .

The working condition judging module 110 is used for judging whether the brushless DC motor is in the low-speed heavy-load working condition.

In the embodiment of the present invention, the working condition determination module 110 can be used to implement the brushless DC motor control method provided in the second embodiment.

The processing module 120 may be an integrated circuit chip with signal processing capability. The above-mentioned processing module 120 can be a general-purpose processor, including a central processing unit (Central Processing Unit, CPU), a network processor (Network Processor, NP), etc.; it can also be a digital signal processor, an application-specific integrated circuit, a field programmable gate Arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. Various methods, steps and logic block diagrams disclosed in the embodiments of the present invention may be implemented or executed. The general processor may be a microprocessor or the processing module 120 may be any conventional processor or the like.

Specifically, the processing module 120 is used to control the brushless DC motor through the comparison result of the current given value of the brushless DC motor and the current average value of the brushless DC motor after determining that the brushless DC motor enters a low-speed and heavy-load working condition. The corresponding power tube is turned on or off when the Hall signal combination of the motor is turned on.

In the embodiment of the present invention, the processing module 120 may be configured to execute the low-speed and heavy-load control method of the brushless DC motor provided in the first embodiment after determining that the brushless DC motor enters a low-speed and heavy-load working condition.

Please refer to FIG. 6 , the working condition judgment module 110 includes a detection sub-module 111 and a judgment sub-module 112.

The detection sub-module 111 is used to detect the output voltage V _o of the speed control handle and the speed S of the brushless DC motor.

In the embodiment of the present invention, the detection sub-module 111 may be used to execute step S310.

The determination sub-module 112 is used to determine that if the duration T _o of the output voltage V _o is at the maximum value is not less than 3 s, and the speed S of the brushless DC motor is not greater than 10% of the rated speed _Ne of the brushless DC motor, It is determined that the brushless DC motor enters the low-speed and heavy-load working condition; otherwise, it is determined that the brushless DC motor does not enter the low-speed and heavy-load working condition.

In the embodiment of the present invention, the determination sub-module 112 may be used to execute step S320.

Please refer to FIG. 7 , the processing module 120 includes a first setting submodule 121 , a second setting submodule 122 and a comparison submodule 123 .

The first setting sub-module 121 is used for setting the given current value I _set .

In the embodiment of the present invention, the first setting sub-module 121 may be used to execute step S210.

The second setting sub-module 122 is used to set the average current value I _p .

In the embodiment of the present invention, the second setting submodule 122 may be used to execute step S220.

The comparison sub-module 123 is used to compare the current given value I _set with the current average value I _p , and if the current given value I _set is greater than or equal to the current average value I _p , then according to the brushless DC motor Hall signal combination Turn on the corresponding power tube; if the current given value I _set is less than the current average value I _p , then turn off all the power tubes.

In the embodiment of the present invention, the comparison sub-module 123 may be used to execute step S230.

In summary, the present invention provides a brushless DC motor control method and device and its low-speed and heavy-load control method, wherein the brushless DC motor low-speed and heavy-load control method uses the current given value of the brushless DC motor and the brushless The comparison result of the current average value of the DC motor is used to control the corresponding power tube to be turned on or off when the Hall signal combination of the brushless DC motor is turned on. The brushless DC motor can still output as much torque as possible for a long time under low-speed and heavy-load conditions, and effectively reduce the switching frequency of the power tube, reduce the heat generation of the control system, and improve the efficiency of power utilization.

Inspired by the above-mentioned ideal embodiment according to the present invention, through the above-mentioned description content, relevant workers can make various changes and modifications within the scope of not departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, but must be determined according to the scope of the claims.

Claims (6)

1. A low-speed heavy-load control method for a brushless DC motor is characterized by comprising the following steps

Controlling the Hall signal combination of the brushless DC motor to open or close the corresponding power tube according to the comparison result of the current set value of the brushless DC motor and the current average value of the brushless DC motor;

the method for obtaining the comparison result comprises the following steps:

setting the given value of current I_set；

Setting the current average value I_p；

Setting the current to a given value I_setAnd the average value of the current I_pThe comparison is carried out, and the comparison is carried out,if the given value of current I_setGreater than or equal to the average value of current I_pThen, corresponding power tubes are switched on according to the Hall signal combination of the brushless direct current motor; if the given value of current I_setLess than the current average value I_pAnd all power tubes are turned off.

2. The method for controlling the low speed and heavy load of the brushless DC motor according to claim 1,

given value of current I_setThe obtaining method comprises the following steps:

obtaining the average value S of the rotating speed of the brushless DC motor in the electric time period from the initial moment when the brushless DC motor enters the low-speed heavy-load working condition_p；

According to the average value S of the rotating speed_pCalculating the given value of current I_set。

3. The method according to claim 2, wherein said average value S is based on said rotation speed_pCalculating the given value of current I_setComprises the following steps:

adjusting rated working current I of power tube_e；

Adjusting the rated speed N of the brushless DC motor_e(ii) a And

given value of current I_set＝(-5I_e*S_p/N_e)+I_eAnd S is_pIs initially set to 0.1N_e。

4. A brushless DC motor control method is characterized by comprising the following steps:

after determining that the brushless DC motor enters the low-speed heavy-load working condition, performing low-speed heavy-load control on the brushless DC motor by the low-speed heavy-load control method of the brushless DC motor according to any one of claims 1 to 3.

5. The brushless DC motor control method according to claim 4,

the method for judging the brushless direct current motor to enter the low-speed heavy-load working condition comprises the following steps:

detecting output voltage V of speed-regulating rotating handle_oAnd the rotating speed S of the brushless DC motor;

if the output voltage V is_oDuration T at maximum_oIs not less than 3S, and the rotating speed S of the brushless DC motor is not more than the rated rotating speed N of the brushless DC motor_eWhen the speed is 10 percent, judging that the brushless direct current motor enters a low-speed heavy-load working condition; otherwise, judging that the brushless direct current motor does not enter a low-speed heavy-load working condition.

6. A brushless DC motor control device, comprising:

the working condition judging module is used for judging whether the brushless direct current motor enters a low-speed heavy-load working condition or not;

the processing module is used for controlling the Hall signal combination of the brushless DC motor to open or close the corresponding power tube according to the comparison result of the current given value of the brushless DC motor and the current average value of the brushless DC motor after judging that the brushless DC motor enters the low-speed heavy-load working condition;

the operating condition determining module includes:

a detection submodule for detecting the output voltage V of the speed-regulating rotating handle_oAnd the rotating speed S of the brushless DC motor;

a determination submodule for determining if the output voltage V is lower_oDuration T at maximum_oIs not less than 3S, and the rotating speed S of the brushless DC motor is not more than the rated rotating speed N of the brushless DC motor_eWhen the speed is 10 percent, judging that the brushless direct current motor enters a low-speed heavy-load working condition; otherwise, judging that the brushless direct current motor does not enter a low-speed heavy-load working condition;

the processing module comprises:

a first setting submodule for setting the current setpoint I_set；

A second setting submodule for setting the current average value I_p；

A comparison submodule for setting the current to a given value I_setAnd the average value of the current I_pThe comparison is carried out, and the comparison is carried out,if the given value of current I_setGreater than or equal to the average value of current I_pThen, corresponding power tubes are switched on according to the Hall signal combination of the brushless direct current motor; if the given value of current I_setLess than the current average value I_pAnd all power tubes are turned off.