KR20120137897A - A method for discriminating the malfuncition of bldc motor control system - Google Patents

Abstract

PURPOSE: A malfunction determination method over the hall device of the BLDC motor control system is provided to easily conduct the fault diagnosis and repair of the BLDC motor. CONSTITUTION: The method thereof determines whether the sum of output values(Hu, Hv, Hw) of three hall devices for detection(110a, 110b, 110c) is beyond the prescribed error range from the zero value or not. In case of deviating from error range, an abnormal occurrence is determined at the hall device. A BLDC motor(100) is controlled by a sensor less method. [Reference numerals] (A1) Hall device(110a) output; (A2) Hall device(110b) output; (A3) Hall device(110c) output; (BB) Micro-controller

Description

A method for judging an error in Hall element of a DCC motor control system {A METHOD FOR DISCRIMINATING THE MALFUNCITION OF BLDC MOTOR CONTROL SYSTEM}

The present invention relates to a Hall element abnormality determination method of a BLDC motor, and more particularly, to determine the abnormal state of the Hall element by determining the output synthesis value of the three Hall elements used for rotor position determination of the BLDC motor. It relates to a device abnormality determination method.

In general, BLDC (Brushless DC) motor is designed to remove the brush acting as a commutator in the DC motor and to maintain the properties of the DC motor, the configuration of the three-phase coil (U-phase coil, V-phase coil, W-phase) A stator made of a coil), a rotor made of a permanent magnet, and a position detecting element.

The BLDC motor flows a current through each phase of the stator side coil of the BLDC motor, and causes the magnetic field to be generated by the current to rotate the rotor. At this time, the BLDC motor detects the strength of the rotor's magnetic field, and the rotor continues in one direction by sequentially turning on / off switching elements for changing the direction of the current flowing in each phase of the coil according to the detected magnetic field. To rotate.

That is, the BLDC motor detects the position of the rotor, which is performed by the brush, through a Hall element using the strength of the magnetic field of the rotor, without using a brush, and controls the position of the BLDC motor rotor using the detected signal. A predetermined position control signal is generated.

In order to continuously rotate the rotor of the motor in one direction, the position of the rotor (the strength of the magnetic field of the rotor) is detected, and the direction of the current flowing in each phase of the coil is changed according to the detected position of the rotor. Switching elements must be turned on and off sequentially.

At this time, the exact position of the rotor can be known through three signals formed by the magnetic field of the rotor and having a phase difference of 120 °. These three Hall signals are detected by a Hall detector such as a Hall sensor or Hall IC. do.

Such a BLDC motor and a driving circuit will be described in more detail with reference to FIG. 1. As shown in FIG. 1, the BLDC motor 100 and the motor driving circuit 200 constitute a BLDC motor system.

The BLDC motor 100 includes three-phase coils 130 (U-phase, V-phase, and W-phase) provided on the stator side, and the strength of the magnetic field of the permanent magnet and the rotor provided on the rotor side (rotor). And three Hall elements 110a, 110b, and 110c for detecting the position of.

In Fig. 1, each of the Hall elements 110a, 110b, and 110c corresponds to the intensity of the magnetic field of the rotor (position of the rotor) and a pair of signals (hole signal pairs) having a 180 ° phase difference (Hu +, Hu). Outputs Hv +, Hv-; Hw +, Hw-). Here, the signals Hu +, Hv +, and Hw + output from the respective hall elements 110a, 110b, and 110c have a phase difference of 120 °.

On the other hand, the motor driving circuit 200 generates a constant three-phase reference signal by receiving a signal output from the Hall element, the current for 180 ° energization to the three-phase coil 130 by using the generated constant three-phase reference signal Supplying to control the rotation of the rotor (120). As shown in FIG. 1, the motor driving circuit 200 includes a reference signal generator 220 and a motor driver 240.

The reference signal generator 220 receives a signal (Hu +, Hu-; Hv +, Hv-; Hw +, Hw-) output from the Hall element, and corresponds to the three-phase for controlling the motor driver 460. Output the reference signals (isou, isov, isow). The reference signal generator 220 is a three-phase reference signal that is constant even if the amplitude of the signals Hu +, Hu-; isou, isov, isow), a detailed method for this is described below.

Here, the three-phase reference signals (isou, isov, isow) are generated corresponding to the signals (Hu +, Hu-; Hv +, Hv-; Hw +, Hw-) output from the Hall element, and thus the three-phase reference signals (isou, isov). isow) also contains information on the strength of the rotor's magnetic field (position of the rotor).

On the other hand, the motor driver 240 receives the three-phase reference signals (isou, isov, isow) output from the three-phase reference signal generator 220, thereby changing the direction of the current flowing in each phase of the coil, Let the rotor continue to rotate in one direction.

Such a BLDC motor and its driving circuit must accurately detect the position of the rotor, and a Hall element for detecting the position of the rotor is required to detect the position.

Although the Hall element has higher precision than other Hall sensors, the Hall element is composed of a semiconductor IC which is weak in heat, and thus has a higher risk of heat damage than the Hall sensor. However, if the Hall element is damaged by heat or normal operation is impossible, it is difficult to operate the motor normally. Therefore, if the Hall element cannot be used due to damage, the motor may be driven in a sensorless manner. There is no choice but to.

Therefore, the present invention has been made to solve the above-mentioned conventional problems, an object of the present invention is a Hall element abnormality determination method that can facilitate the determination of the abnormality of the Hall element for detecting the rotor position in the BLDC motor To provide.

Another object of the present invention is to provide a Hall element abnormality determination method that allows the BLDC motor to operate normally by switching the control method of the BLDC motor to a SENSORLESS control method when determining whether the Hall element is abnormal.

In order to achieve the above object, the present invention, a BLDC comprising a permanent magnet on the rotor side, and three detection hall elements arranged on the stator side spaced apart by 45 ° side by side with respect to the three-phase coil and the rotation axis A hall element abnormality determination method of a BLDC motor control system including a motor and a control unit of the BLDC motor, wherein the control unit has a predetermined error in which the combined value of the output values from the three detection hall elements has a value of "0". Determining whether it is out of range; Determining that there is an error in the Hall element when it is out of the error range in the step; And controlling the BLDC motor in a sensorless manner.

Preferably, the step of determining whether the deviation is out of the error range, if within the error range, further comprising the step of determining whether the pattern is constant, if the pattern is constant, it is determined that there is an error in the Hall element It further comprises a step.

As described in detail above, according to the Hall element abnormality determination method of the BLDC motor according to the present invention, the following effects can be expected.

That is, by facilitating the determination of the abnormal state of the Hall element for detecting the rotor position in the BLDC motor, there is an advantage that it is easy to diagnose and repair the failure of the BLDC motor.

In addition, according to the Hall element fault determination method of the BLDC motor according to the present invention, when the malfunction of the Hall element is detected, the BLDC motor can be normally operated by switching the control method of the BLDC motor to a sensorless control method. It has the advantage of improving the operation reliability.

1A schematically illustrates a typical three-phase BLCD motor and its driving circuit.
1B is an output waveform diagram of a typical Hall element.
Figure 2a is a view showing the position of the Hall element for detecting the rotor position in a specific embodiment of the present invention.
Figure 2b is a view showing the output signal of each Hall sensor according to the position of the Hall element as shown in Figure 2a in a specific embodiment of the present invention.
3 is a waveform diagram of a three-phase AC sine wave generated by three Hall elements in a specific embodiment of the present invention.
Fig. 4 shows one embodiment for synthesizing output values from three Hall elements.
Fig. 5 shows another embodiment for synthesizing output values from three Hall elements.
Fig. 6A is an output waveform diagram when all three Hall elements are normal.
6B is an output waveform diagram when an abnormality occurs in one of three Hall elements.
Fig. 7A is a waveform diagram showing a ripple state in the combined output value when all three Hall elements are normal.
Fig. 7B is a waveform diagram showing a ripple state in the combined output value when abnormality among three Hall elements occurs.
8 is a flowchart illustrating a Hall sensor malfunction detection method and a motor control method using the same according to a specific embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, a specific embodiment of the Hall element abnormality determination method of the BLDC motor and the BLDC motor control method according to the present invention as described above will be described in detail.

Figure 2a is a view showing the position of the Hall element for detecting the rotor position in a specific embodiment of the present invention, Figure 2b is a view showing the output signal of each Hall sensor according to the position of the Hall element, Figure 3 is three Hall elements Figure 3 is a waveform diagram of a three-phase AC sine wave generated by the, Figure 4 is a flow chart showing a step-by-step detection method and a motor control method using the hall sensor abnormality.

In a BLDC motor, the stator consists of a plurality of coil windings in three phases that match the number of magnets of the rotor composed of permanent magnets. Magnets mounted to the rotor are generally ceramic magnets. The coil winding installed in the stator and the permanent magnet installed in the rotor form a magnetic flux density distribution on the rotor so that when the rotor is rotated at a constant speed, a trapezoidal electromagnetic driving force (EMF) waveform as shown in FIG. Guided to the coil windings. The cumulative effect of trapezoidal electromagnetic driving force (EMF) for each phase is to generate a substantially flat waveform with respect to the induced current of the stator.

When the rectangular current blocking signal shown in Fig. 1B is applied to the coil winding of the stator, a constant torque is generated. It can be seen that the blocking operation of the current is applied discontinuously over 120 ° as opposed to the application of a continuous sinusoidal current over 180 ° in the AC servo motor shown in FIG. 1A. This discontinuous current commutation from one coil winding to another coil winding is a major cause of the cogging characteristics of a brushless dc motor.

The amplitude of the electromagnetic driving force EMF is proportional to the speed, and the speed is adjusted by controlling the voltage amplitude of the signal applied to the coil winding of the stator. The amplitude of the current interruption in the stator is linearly proportional to the generated torque and controls the generated torque. Regardless of the position of the rotor, in order to generate a uniform torque, the commutation of the current must occur according to the predetermined angle of the rotor. These angles are detected by three Hall effect detection sensors mounted on the fault, and provide feedback information to the motor controller to switch the rotor current of the motor. In addition, a low cost, low resolution tachometer can be used to provide the speed signal of the rotor.

From the commutation operation logic, the current-torque and voltage-speed characteristics of the BLDC motor are similar to those of the brushed DC motor. As a result, the regulating circuit for the BLDC motor is very simple and can be configured to be compatible with the regulating characteristics for brush-type DC motor driving.

2A and 2B, Hall elements included in each Hall element 110a, 110b, 110c in the error detection method of the Hall element for detecting the rotor position of the BLDC motor according to a specific embodiment of the present invention. (Ha, Hb, Hc) are arranged side by side at 45 ° apart from each other about the axis on the stator side. On the other hand, the permanent magnets installed on the rotor side are alternately arranged with two poles of N pole and S pole over 90 ° about the axis of the rotor. According to the arrangement of the hall element and the permanent magnet as described above, each of the hall elements 110a, 110b, and 110c outputs a signal as shown in FIG. 2B.

3 shows waveforms by these three Hall elements 110a, 110b, 110c. As shown in the figure, since the Hall elements have an electrical phase difference of 120 °, the waveform of the signals they output eventually becomes the form of a three-phase AC waveform.

As shown in the figure, it can be seen that the output values Hu, Hv, and Hw from the three Hall elements 110a, 110b, and 110c become "0" at any point in time. However, when any one of the three Hall elements fails to operate normally due to thermal shock or other external factors, the sum of the output values (Hu, Hv, Hw) from these three Hall elements does not have the correct value of "0". It does not indicate the error.

Therefore, in the present invention, the synthesized value of (Hu, Hv, Hw) output from the hall elements 110a, 110b, and 110c in the motor driving circuit 200 may not converge to “0” or may be out of a certain error range. In this case, this is regarded as a malfunction of the hall elements 110a, 110b, and 110c. Then, the BLDC motor 100 is driven according to the sensorless control method.

4 is a view showing an embodiment for synthesizing output values from three Hall elements 11a, 110b, and 110c to determine whether an Hall element is abnormal according to the method of the present invention.

As a means for synthesizing the output value of the Hall element for implementing the method of the present invention, various methods well known to those skilled in the art can be used. As an example, as shown, the outputs from the three Hall elements 11a, 110b, and 110c are each input to a diode, whereby a composite value of the output signal is obtained, and this composite output value constitutes a controller. It is input to the microprocessor and used as a motor drive signal.

Fig. 5 shows another embodiment for synthesizing output values from three Hall elements, in which the outputs from the three Hall elements 11a, 110b and 110c are the ACD (Analog-) of the microprocessor. To-Digital) is input to each port, and shows a method for outputting the composite value in software through operations in the microprocessor.

When synthesizing the signals output from the three Hall elements 11a, 110b, and 110c through the above method, when the three Hall elements operate normally without any abnormality, an output waveform as shown in FIG. 6A is displayed. The outputs (Hu, Hv, Hw) from the three Hall elements 11a, 110b, and 110c have the form of a three-phase AC waveform having a phase difference of 120 ° as described above. In the ripple state, a waveform as shown in Fig. 7A is shown.

Considering that the three Hall elements 11a, 110b, and 110c are not ideal elements, the output composite value therefrom exhibits some ripple due to the tolerance. Therefore, even if the output synthesis value does not become zero, when the ripple waveform is within the normal error range, the three Hall elements 11a, 110b, and 110c are considered to be in a steady state.

On the contrary, for example, when an abnormality occurs in the Hall element 110c among the three Hall elements 11a, 110b, and 110c, its output value Hw shows a waveform as shown in Fig. 6B, and thus the output synthesis value A waveform as shown in FIG. 7B is shown.

That is, when any one of the three Hall elements 11a, 110b, 110c is not in a normal state, the ripple in the waveform of the output synthesis value thereof appears much larger than the normal error range. The control unit of the BLDC motor control system determines that there is an abnormality in the hall element, and controls the BLDC motor in a sensorless manner.

This process will be described with reference to the flowchart shown in FIG. 8. First, when driving of the BLDC motor 100 starts, the Hall elements 110a, 110b, and 110c are initialized (S100).

The control unit, which is the motor driving circuit 200, continuously monitors whether or not the combined value of the output values Hu, Hv, and Hw from the Hall elements 110a, 110b, and 110c is "0" (S200). ).

Here, when the error signal is the combined value of the output values Hu, Hv, and Hw from the Hall elements 110a, 110b, and 110c is a value of "0" or is within a certain error range, the Hall elements 110a, Although the control method of the BLDC motor 100 is continued using the 110b and 110c, the output values Hu, Hv and Hw from the Hall elements 110a, 110b and 110c are maintained in the step S200. If the synthesized value is not "0" or is out of a certain error range, the BLDC motor 100 is switched to the sensorless method by ignoring the signals received from the Hall elements 110a, 110b, and 110c. (S300).

Here, the sensorless control scheme used in the 300th step S300 may include all of the various sensorless control schemes known before the application of the present invention. According to this, the position of the rotor can be determined using the current or the counter electromotive force of the BLDC motor 100.

The BLDC motor 100 may be stably controlled by driving the BLDC motor 100 according to the determined control method regardless of whether the Hall elements 110a, 110b, 110c are abnormal.

On the other hand, according to the control method described above, whether the combined values of the output values Hu, Hv, and Hw from the three detection hall elements 110a, 110b, and 110c deviate from a value of "0" by a predetermined error range. As a result of judging whether or not the ripple value is within the error range, when the pattern in the waveform is constant as shown in Fig. 7B, some of the three Hall holes 110a, 110b, and 110c are detected. It is determined that there is an abnormality in self, and the controller similarly controls the BLCD motor in a sensorless manner (S500).

According to the embodiment of the present invention as described above, it is possible to determine whether the Hall element is abnormal by logic alone without adding a new configuration, and accordingly, the stable control of the BLDC motor can be performed.

The rights of the present invention are not limited to the embodiments described above, but are defined by the claims, and those skilled in the art can make various modifications and adaptations within the scope of the claims. It is self-evident.

Claims (2)

A BLDC motor 100 including permanent magnets on the rotor side and three detection hall elements 110a, 110b, and 110c disposed on the stator side and spaced apart by 45 ° with respect to the three-phase coil and the rotating shaft. And a Hall element abnormality determination method of a BLDC motor control system including a control unit of the BLDC motor 100.
(A) determining whether the combined values of the output values Hu, Hv, and Hw from the three detection Hall elements 110a, 110b, and 110c are out of a predetermined error range from a value of "0";Wow;
(B) determining that there is an error in the Hall element when it is out of the error range in the step (a); And
(C) Hall element abnormality determination method of the BLDC motor control system comprising the step of controlling the BLDC motor 100 in a sensorless manner. The method of claim 1, wherein the step (a) is within the error range,
(D) further comprising determining whether the pattern is constant,
If the pattern is constant in the step (d), further comprising the step of determining that there is an error in the Hall element Hall element abnormality determination method of the BLDC motor control system.

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