KR20210085058A - Method and Apparatus for Controlling Brushless Direct Current Motor Using Hall Sensor - Google Patents

Abstract

Disclosed are a BLDC motor control device using a hall sensor and a method thereof. According to the present embodiment, provided are the BLDC motor control device and the method thereof which filter a hall sensor output and provide the output, from which a glitch of a transient state is removed, to a motor when a brushless direct current (BLDC) motor rotates at a low speed, wherein the BLDC motor is operated in a 6 step square wave control method by using a hall sensor, thereby smoothly controlling the motor of the low speed.

Description

BLDC motor control device and method using Hall sensor {Method and Apparatus for Controlling Brushless Direct Current Motor Using Hall Sensor}

The present invention relates to an apparatus and method for controlling a BLDC motor using a hall sensor.

The content described below merely provides background information related to the present invention and does not constitute the prior art.

A brushless direct current (BLDC) motor is one of DC driving motors, and includes a rotor implemented with a permanent magnet and a stator on which a coil is wound. A general DC motor requires a commutator and a brush to change the polarity of the DC power, but the BLDC motor operates without a commutator and brush. In order to maintain rotation, the DC power supplied from the outside must operate like an AC inside the motor. The BLDC motor uses a Hall sensor included in the motor to control the direction of power supplied to the windings of the stator. do.

As shown in FIG. 5 , in the BLDC motor, the stator is typically implemented in a 3-phase form. Hall sensors are arranged at intervals of 120 degrees between the three-phase stators. The Hall sensor operates based on the Hall effect, and serves to detect the strength of a magnetic field when a magnet approaches. A low-cost Hall sensor used to control a motor generates a binary output according to the polarity of a magnetic field.

As a representative control method for a BLDC motor using a Hall sensor, there is a 6-step square wave control method as shown in FIG. 6 . In order to explain the operation of the six-step square wave control (hereinafter 'square wave control') method, as shown in FIG. 5, the three phases of the stator are expressed as A, B, and C, respectively, and the Hall sensor disposed between the stators is Expressed as HA, HB, and HC, respectively. It is assumed that if the positive current flows in the winding of the stator, it becomes N pole, and when negative current flows, it becomes S pole. It is assumed to output 1 (high) when approaching. The BLDC motor shown in FIG. 5 includes a two-pole rotor in its simplest form.

In step 1 as shown in Fig. 5, in order to rotate the BLDC motor counterclockwise (counter clock-wise), the A phase becomes the N pole and pushes the rotor, and the B phase becomes the S pole and rotates It attracts electrons, and phase C remains in the float state. At this time, the Hall sensor HA outputs 0 because the S pole approaches, the Hall sensor HB outputs 1 because the N pole approaches, and the HC outputs 0 because the S pole approaches. That is, when the HC/HB/HA combination is 010, the switching element is adjusted so that the current that becomes the N pole of the A phase and the S pole of the B phase flows. Since a similar explanation is possible for the remaining steps, the square wave control method is summarized in a timing chart as shown in Fig. 6 (a) and a current flow in the three phases of the stator as shown in Fig. 6 (b). can be

The square wave control method maintains the rotation of the BLDC motor by providing a discontinuous output in which the Hall sensor differs in electrical angle by 60 degrees for each step, and adjusting the switching element using this output. . In addition, the square wave control method calculates the rotation speed using the frequency of the electric angle output from the Hall sensor, and then adjusts the intensity of the current flowing through the stator winding in a direction to reduce the difference from the target speed. control the rotation speed of

Since the square wave control method uses a Hall sensor and a switching element to control the BLDC motor, it is possible to implement and control it relatively simply, and thus the implementation cost is low. Therefore, when economical efficiency is to be considered first, a BLDC motor using a square wave control method is widely used.

When the motor rotates at a high speed, there is no major problem in controlling the BLDC motor using the Hall sensor as described above. On the other hand, when the motor rotates at a low speed, the control of the BLDC motor is not easy because the position resolution that the discontinuous electric angle output of the Hall sensor can provide is low. It may not be a problem when the load is small, but there is a serious problem in the control of the BLDC motor especially when the load is large.

Accordingly, there is a need for a method for smoothly operating a BLDC motor in a low-speed rotating state.

In the present disclosure, when a brushless direct current (BLDC) motor operating in a 6 step square wave control method using a Hall sensor rotates at a low speed, the Hall sensor output is filtered to A main object is to provide a BLDC motor control apparatus and method for smoothly controlling a low-speed motor by providing an output from which a glitch is removed to a motor.

According to an embodiment of the present invention, in the apparatus for controlling a brushless direct current (BLDC) motor using a hall sensor, when the BLDC motor operates at a low speed below a preset threshold velocity, the hall a low-speed control unit generating an output from which a glitch existing in an output of a transient state of the sensor is removed; and a square wave control unit generating a square wave signal for controlling the BLDC motor by using the output generated by the low speed control unit.

According to another embodiment of the present invention, in the BLDC motor control method of a brushless direct current (BLDC) motor control apparatus using a Hall sensor, the rotation speed of the BLDC motor is calculated by acquiring the output of the Hall sensor. process; calculating a filter coefficient of a status filter based on the rotation speed when the BLDC motor operates at a low speed below a preset threshold velocity; generating an output from which a glitch of a transient state is removed by inputting the output of the Hall sensor to the state filter; When operating at the low speed, it provides a BLDC motor control method comprising the step of controlling the BLDC motor in a square wave control method using the output of the state filter.

According to another embodiment of the present invention, there is provided a computer program stored in a computer-readable recording medium to execute each step included in the LDC motor control method.

As described above, according to the present embodiment, when a brushless direct current (BLDC) motor operating in a 6 step square wave control method using a Hall sensor rotates at a low speed, the Hall sensor There is an effect that it becomes possible to smoothly control a low-speed motor by providing a BLDC motor control apparatus and method for filtering an output and providing an output from which a glitch in a transient state is removed to a motor.

1 is a block diagram of a low-speed BLDC motor control apparatus according to an embodiment of the present invention.
2 is an exemplary diagram illustrating a transient state of a Hall sensor output occurring at a low speed.
3 is a conceptual diagram of a filter coefficient calculation of a state filter and input and output of a state filter according to an embodiment of the present invention.
4 is a flowchart of a low-speed BLDC motor control method according to an embodiment of the present invention.
5 is an internal conceptual diagram of a BLDC motor.
6 is a conceptual diagram of a 6-step square wave control method, which is a conventional BLDC motor control method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, in describing the present embodiments, if it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present embodiments, the detailed description thereof will be omitted.

Also, in describing the components of the present embodiments, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, or order of the elements are not limited by the terms. Throughout the specification, when a part 'includes' or 'includes' a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated. . In addition, the '... Terms such as 'unit' and 'module' mean a unit that processes at least one function or operation, which may be implemented as hardware or software or a combination of hardware and software.

DETAILED DESCRIPTION The detailed description set forth below in conjunction with the appended drawings is intended to describe exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced.

This embodiment discloses the contents of a BLDC motor control apparatus and method using a hall sensor. In more detail, when a brushless direct current (BLDC) motor operating in a 6 step square wave control method using a Hall sensor rotates at a low speed, the Hall sensor output is filtered to A BLDC motor control apparatus and method for providing a glitch-free output to a motor are provided.

Hereinafter, it is assumed that the motor is a BLDC motor. The BLDC motor is one of the DC driving motors, and operates without a commutator and a brush required to change the polarity of the DC power.

It is assumed that the velocity (velocity) means the rotational speed (Revolution Per Minute: RPM) of the BLDC motor.

As shown in Fig. 4, the BLDC motor assumes that the stator is implemented in a three-phase form. Accordingly, the Hall sensor included in the BLDC motor provides a discontinuous output in which the electrical angle differs by 60 degrees.

1 is a block diagram of a low-speed BLDC motor control apparatus according to an embodiment of the present invention.

In the embodiment of the present invention, when the motor 103 rotates at a low speed, the BLDC motor control device 100 filters the Hall sensor output and provides an output from which a glitch in a transient state is removed to the motor. . The BLDC motor control apparatus 100 includes all or a part of the low speed control unit 101 and the square wave control unit 102 .

The low speed control unit 101 according to the present embodiment controls the BLDC motor 103 by providing the output of the Hall sensor to the square wave control unit 102 at high speed, and outputs the glitch-removed output to the square wave control unit 102 at low speed. ) to control the BLDC motor 103 .

In order to maintain the rotation of the BLDC motor 103, a means for alternately operating the supplied DC power like AC is required. This embodiment is limited to the field of controlling the BLDC motor 103 using the square wave control method.

In the square wave control method, the Hall sensor provides a discontinuous output in which the electrical angle differs by 60 degrees for each 6 step, and by using this output to control the switching element, the rotation of the BLDC motor 103 is to keep In addition, the square wave control method calculates the rotation speed using the frequency of the electric angle output by the Hall sensor, and then adjusts the intensity of the current flowing through the stator winding in a direction to reduce the difference from the target velocity. 103) to control the rotation speed.

When rotating at high speed, there is no big problem in controlling the motor using the Hall sensor. On the other hand, when rotating at a low speed, it is not easy to control the motor because the position resolution that the discontinuous electric angle output of the Hall sensor can provide is low.

As shown in FIG. 2 , a glitch may occur in a transient state, that is, an edge at which the output of the Hall sensor changes. Therefore, due to the low resolution of the Hall sensor, even if the electric angle on the input side of the Hall sensor is slightly changed to the level of 1 degree, the output current depending on the square wave in the transient state changes by 60 degrees, and the operation of the motor may become unstable. . When the load applied to the motor is small, it may not be a problem, but when the load is large, the control part of the BLDC motor 103 diverges or resonates, which may cause serious problems in the control of the motor. Here, the glitch in the Hall sensor output occurs when the motor is rotated in the opposite direction when a high load is applied in one direction at low speed.

In order to suppress the operation instability in such a transient state, the low speed control unit 101 according to the present embodiment removes glitches that may exist in the transient state of the Hall sensor output at low speed.

The low speed control unit 101 may execute an operation necessary for controlling the BLDC motor 103 at a low speed using a programmable microcontroller unit (MCU) and a program and data stored in a recording medium.

(제어 주파수는 40 KHz))을 유지한다. 이는 상대적으로 고주파 신호인 글리치를 제거하는 것이 용이하도록 충분한 처리 대역(processing bandwidth)를 확보하기 위함이다. In the present embodiment, the square wave control period of the low-speed control unit 101 is set to a value as high as possible (eg, 25

(control frequency is 40 KHz)). This is to secure sufficient processing bandwidth to easily remove glitches, which are relatively high-frequency signals.

In addition, before the output of the Hall sensor is fed back to the square wave control unit 102 , the low speed control unit 101 obtains the voltage output from the Hall sensor and uses it to remove the glitch. By generating a current for controlling the motor using the voltage from which the glitch is removed, the unstable current flow is suppressed in the low-speed transient state as described above so that the motor operates smoothly.

The low speed control unit 101 includes all or a part of the speed calculating unit 110 , the coefficient calculating unit 111 , the state filter 112 , and the output selecting unit 113 .

The speed calculator 110 calculates the rotation speed of the BLDC motor 103 using the output of the Hall sensor. The speed calculation unit 110 may calculate the rotation speed of the BLDC motor 103 by using the periodicity included in the output of the Hall sensor.

As shown in (a) of FIG. 3 , the coefficient calculating unit 111 calculates the filter coefficients of the state filter 112 at a low speed equal to or less than a _{preset threshold velocity x 2 .}

The coefficient of the state filter 112 is 0 or a natural number, and an embodiment for determining the filter coefficient is as follows. At another preset critical speed x ₁ (<x ₂ ) or less, the coefficient calculating unit 111 selects _{y 1 as a filter coefficient.} When the speed is _{greater than x 1} and less than or equal to the preset critical speed x ₂ , the coefficient calculating unit 111 selects a linearly reduced value (<y ₁ ) as a filter coefficient as shown in FIG. 3A . do. When the speed is _{higher than the preset threshold speed x 2} , the filter coefficient is 0 because the state filter is not used.

The state filter 112 is a kind of lowpass filter (LPF), and uses selected filter coefficients to remove glitches corresponding to high-frequency signals as follows. The state filter 112 outputs the observed electrical angle of the Hall sensor only when the same output of the Hall sensor is continuously observed as many times as the number of times corresponding to the filter coefficient under a preset threshold speed. On the other hand, when the same output of the Hall sensor is not continuously observed as many times as the number of times corresponding to the filter coefficient, the state filter 112 maintains the electric angle of the previous state.

When the state filter 112 is applied, a delay may occur in the control process of the BLDC motor 105, but since the state filter 112 is applied at a low speed and operated in the transient state portion of the Hall sensor, the overall operation of the motor is affected. no big impact

The output selection unit 113 provides the output of the state filter 112 to the square wave controller 102 at a low speed below a preset threshold speed, and at a high speed exceeding a preset threshold speed, outputs the output of the Hall sensor to the square wave controller (102).

The square wave control unit 102 according to the present embodiment generates a square wave signal for controlling the rotation speed of the BLDC motor 105 by using the output of the Hall sensor provided by the low speed control unit 101 .

1 is an exemplary configuration according to the present embodiment, and depending on the shape of the low speed control unit and the square wave control unit, it is possible to implement including other components or other connections between components.

4 is a flowchart of a low-speed BLDC motor control method according to an embodiment of the present invention.

The BLDC motor control device 100 acquires the output of the hall sensor (S401). In a transient state at low speed, that is, at an edge where the output of the Hall sensor changes, the output of the Hall sensor may include a glitch.

The BLDC motor control apparatus 100 calculates the speed of the BLDC motor using the output of the Hall sensor (S402). The speed of the BLDC motor 103 may be generated using the periodicity included in the output of the Hall sensor.

The BLDC motor control apparatus 100 generates filter coefficients of the state filter based on the speed of the BLDC motor when the BLDC motor operates at a low speed below a preset threshold velocity (S403). The filter coefficient of the state filter 112 is 0 or a natural number, and since the embodiment for obtaining the filter coefficient has been described above, it is omitted here.

The BLDC motor control device 100 inputs the output of the Hall sensor to the state filter to generate an output from which the glitch of the transient state is removed (S404).

The state filter 112 is a kind of lowpass filter (LPF), and uses selected filter coefficients to remove glitches corresponding to high-frequency signals as follows. The state filter 112 outputs the observed electrical angle of the Hall sensor only when the same output of the Hall sensor is continuously observed as many times as the number of times corresponding to the filter coefficient under a preset threshold speed. On the other hand, when the same output of the Hall sensor is not continuously observed as many times as the number of times corresponding to the filter coefficient, the state filter 112 maintains the electric angle of the previous state.

The BLDC motor control apparatus 100 controls the BLDC motor in a square wave control method using the output of the state filter when the speed is low (S405).

The BLDC motor control device 100 controls the speed of the BLDC motor 103 in a square wave control method using the output of the state filter 112 below a preset threshold speed, and at a high speed exceeding the preset threshold speed, The speed of the BLDC motor 103 is controlled in a square wave control method using the output of the Hall sensor.

As described above, according to the present embodiment, when a brushless direct current (BLDC) motor operating in a 6 step square wave control method using a Hall sensor rotates at a low speed, the Hall sensor output By providing a BLDC motor control device and method that provides a motor with an output from which a glitch in a transient state has been removed by filtering it, it is possible to smoothly control a low-speed motor.

Although it is described that each process is sequentially executed in each flowchart according to the present embodiment, the present invention is not limited thereto. In other words, since it may be applicable to change and execute the processes described in the flowchart or to execute one or more processes in parallel, the flowchart is not limited to a time-series order.

Various implementations of the systems and techniques described herein include digital electronic circuitry, integrated circuits, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), computer hardware, firmware, software, and/or combination can be realized. These various implementations may include being implemented in one or more computer programs executable on a programmable system. The programmable system includes at least one programmable processor (which may be a special purpose processor) coupled to receive data and instructions from, and transmit data and instructions to, a storage system, at least one input device, and at least one output device. or may be a general-purpose processor). Computer programs (also known as programs, software, software applications or code) contain instructions for a programmable processor and are stored on a "computer-readable recording medium".

Various implementations of the systems and techniques described herein may be implemented by a programmable computer. Here, the computer includes a programmable processor, a data storage system (including volatile memory, non-volatile memory, or other types of storage systems or combinations thereof), and at least one communication interface. For example, a programmable computer may be one of a server, a network appliance, a set-top box, an embedded device, a computer expansion module, a personal computer, a laptop, a Personal Data Assistant (PDA), a cloud computing system, or a mobile device.

The above description is merely illustrative of the technical idea of this embodiment, and various modifications and variations will be possible by those skilled in the art to which this embodiment belongs without departing from the essential characteristics of the present embodiment. Accordingly, the present embodiments are intended to explain rather than limit the technical spirit of the present embodiment, and the scope of the technical spirit of the present embodiment is not limited by these embodiments. The protection scope of the present embodiment should be interpreted by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present embodiment.

100: BLDC motor control unit 101: low speed control unit
102: square wave control unit 103: BLDC motor
110: speed calculation unit 111: coefficient calculation unit
112: state filter 113: output selector

Claims (9)

In the BLDC (Brushless Direct Current) motor control device using a Hall sensor,
a low-speed control unit generating an output from which a glitch existing in an output of a transient state of the Hall sensor is removed when the BLDC motor operates at a low speed below a preset threshold velocity; and
A square wave control unit generating a square wave signal for controlling the BLDC motor by using the output generated by the low speed control unit
BLDC motor control device comprising a. According to claim 1,
The Hall sensor is mounted inside the BLDC motor, and when the BLDC motor includes a 3-phase stator, the Hall sensor corresponds to an electrical angle that changes by 60 degrees. BLDC motor control device, characterized in that outputting a discontinuous signal. According to claim 1,
The low speed control unit,
a speed calculator for generating a rotation speed of the BLDC motor by using the output of the hall sensor;
a coefficient calculating unit for calculating filter coefficients at or below the preset threshold speed; and
A state filter that removes the glitch using the filter coefficients
BLDC motor control device comprising a. 4. The method of claim 3,
The filter coefficient is a BLDC motor control device, characterized in that 0 or a natural number. 4. The method of claim 3,
The state filter is
When the same output of the Hall sensor is continuously observed as many times as the number of times corresponding to the filter coefficient, the observed electrical angle of the Hall sensor is outputted, but the same output of the Hall sensor is continuously as many times as the number of times corresponding to the filter coefficient If not observed, BLDC motor control device, characterized in that it maintains the electric angle of the previous state. 4. The method of claim 3,
The low speed control unit,
At the low speed, the output of the state filter is provided to the square wave controller, and at a high speed exceeding the preset threshold speed, the output of the Hall sensor is provided to the square wave controller. In the BLDC motor control method of a BLDC (Brushless Direct Current) motor control device using a Hall sensor,
calculating the rotation speed of the BLDC motor by acquiring the output of the hall sensor;
calculating a filter coefficient of a status filter based on the rotation speed when the BLDC motor operates at a low speed below a preset threshold velocity;
generating an output from which a glitch of a transient state is removed by inputting the output of the Hall sensor to the state filter;
When operating at the low speed, the process of controlling the BLDC motor in a square wave control method using the output of the state filter
BLDC motor control method comprising a. 8. The method of claim 7,
The method of controlling a BLDC motor further comprising the step of controlling the BLDC motor in the square wave control method using the output of the Hall sensor when the preset threshold speed is exceeded. A computer program stored in a computer-readable recording medium to execute each step included in the BLDC motor control method according to any one of claims 7 to 9.

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