KR20190125580A - BLDC Motor Driving Apparatus Having Constant Band Hysteresis Current Controller with Back EMF Phase Shift Error Compensator - Google Patents

Abstract

Torque ripple is always a problem for brushless (BL) DC motor drives. The torque ripple is especially important during a rectification period. The torque ripple is mostly generated due to not only a back EMF phase shift but also an equal but opposite rectified current rate. The present invention provides a BLDC motor driving device having a constant band hysteresis current controller with a back EMF phase shift error compensator in order to minimize total torque ripple.

Description

BLDC Motor Driving Apparatus Having Constant Band Hysteresis Current Controller with Back EMF Phase Shift Error Compensator

The present invention relates to a constant band hysteresis current controller, and more particularly to a BLDC motor drive having a back band EMF phase shift error compensator and a constant band hysteresis current controller capable of reducing overall torque ripple.

BLDC motors are a broad spectrum of consumer electrical applications for high efficiency and low maintenance. However, the simplicity of BLDC motor drives results in significant torque ripple during the commutation period, mainly due to the opposite rectified phase current ratio and back EMF phase error. Torque ripple causes unnecessary problems in some motion control and machine tool applications.

They can lead to speed oscillations leading to performance degradation and can stimulate resonance in the mechanical parts of the drive system that generate acoustic noise and leave visible patterns on high precision machine surfaces in machine tool applications.

To avoid this undesirable effect from torque ripple, various techniques and methods have been published to reduce torque ripple. Most BLDC motors are driven by three-phase inverters with an electrical conduction gap of 120 degrees for each phase that can be produced. Each phase leads to a commutation torque ripple every 60 degrees. The rectified torque ripple is not the same but is caused by the opposite rectified phase current rate.

During the rectification period, the phase current rate may be expressed as in Equations 1 to 3 below.

Where V _d is the DC voltage, i _A , i _B and i _C are the input (A, B and C) phase currents, L is the phase inductance, and (magnetic inductance-mutual inductance) (L _s -M) Is defined. E _m is the back EMF built in phase and can assume A and B phase commutation as follows.

Where e _A , e _B , and e _C are back EMFs, respectively.

Assuming that the phase current during the non-rectification period is I _O , Equations 1 to 3 can be summarized as follows.

B phase current (i _B) at 0 and the approach to the I _O is defined as a turn-on time (rise time) (t _ON), can be expressed as:

If the time until the A phase current i _A becomes 0 in I _O is referred to as a turn-off time (fall time) t _OFF , it may be expressed as follows.

The signal and amount of V _d -4E _m determine the direction and magnitude of the torque and ripple. Slow motor speed V _d For> 4E _m , torque increases with time as i _B reaches I _O earlier than I _A and falls to zero. The torque _Te is represented by the following equation (10).

The torque ripple T _r is then defined as spike form as follows.

If the rising and falling rectified phase current ratios are the same V _d = 4E _m , the torque is constant, so the torque ripple is zero.

High motor speed V _d For <4E _m, makes the _B i so to reach slowly than I _O I _A falls to zero torque (T _e) is decreased with time. The torque ripple T _r is then defined as follows in the form of a dip.

In addition to rectified torque ripple, torque ripple due to back EMF phase shift error occurs during rectification. Most BLDC motors use a position sensor, such as a Hall Effect sensor, to detect the rotor position for commutation. However, sensor mismatches, electromagnetic interference or operation in poor conditions can provide inaccurate information from position sensors.

To overcome this problem, accurate zero-crossing detection of back EMF is required, but sensorless control and driving have been proposed. Zero-crossing detection methods can be divided into three categories: direct back electromotive force detection, indirect back electromotive force detection, and model-based estimation. These three methods have advantages, but there is a general problem with commutation phase shift errors. This can be caused by a variety of causes, such as error in circuit components, limited computation frequency of the microcontroller, phase shift in the filter, and error in the ADC. Additional torque ripple due to rectified phase shift error amplifies the overall torque ripple even further.

: Korean Registered Patent Publication No. 10-1343312

SUMMARY OF THE INVENTION The present invention is designed to solve the above problems, and an object thereof is to provide a BLDC motor driving apparatus having a constant band hysteresis current controller having a counter electromotive force phase shift error compensator capable of controlling switching losses and minimizing total torque ripple. To provide.

It is another object of the present invention to provide a BLDC motor driving apparatus which is the same as the reference phase current but minimizes the rectified torque ripple by the opposite slope, and can reduce the torque ripple due to the back EMF phase shift error by the back EMF phase shift error compensator. There is.

Another object of the present invention is to provide a BLDC motor driving device capable of controlling switching power loss with hysteresis bandwidth.

In order to achieve the above object, the present invention is a BLDC motor for driving a three-phase BLDC motor based on the three-phase current, the mechanical angular velocity and the rotational angular velocity of the rotational position of the motor rotor of the three-phase Brushless DC motor A drive device comprising: a machine angle / electric angle converter for converting and outputting the machine angular velocity into an electric angle; An angular velocity / speed converter for converting the rotational angular velocity into a speed to output an output speed of a motor; A reference phase current generator for generating a reference phase current by comparing the actual output speed of the motor with a reference speed generated by a reference speed generator; And using a constant band comparator having a constant hysteresis band, comparing the feedback three-phase current with a reference phase current to generate a current error, and comparing the current error with upper and lower hysteresis bands to generate a PWM (pulse) pulse. Width modulation) constant band hysteresis current controller for controlling the pulse width of the output voltage; provides a BLDC motor drive comprising a.

The reference phase current generator may increase the reference phase current if the actual output speed is less than the reference speed, and decrease the reference phase current if the actual output speed is greater than the reference speed.

The BLDC motor driving apparatus includes a torque calculator configured to calculate and output an output torque from the three-phase current and the three-phase magnetic flux value; An error generator for outputting an error value by comparing a desired load torque set by a user received from the load torque generator with an output torque of an actual motor received from a torque calculator; An integrator that receives an error value from the error generator and generates an integrated value for each preset sampling period; And a back EMF phase shift compensator for compensating the back EMF phase shift by increasing the output when the error value accumulated in the integrator is a negative value and decreasing the output when the error value is a positive value.

If the output torque is greater than the load torque, the error generator determines that the phase is high upon counter electromotive force zero-crossing detection, so that the error value has a negative value to reduce the speed, and the output torque is smaller than the load torque. In contrast to the above, when the counter electromotive force zero-crossing detection is judged to be a slow phase, the error value may be set to have a positive value to increase the speed.

In addition, the constant band hysteresis current controller may generate a current error comparing the feedback phase current with the reference phase current using a constant band comparator having a constant hysteresis band.

Furthermore, if the current error exceeds the upper hysteresis band Upper HB, the pulse width of the PWM output voltage is reduced, and if the current error falls below the lower hysteresis band Lower HB, The pulse width can be increased.

As described above, in the present invention, a constant band hysteresis current controller having a back EMF phase shift error compensator can be used to control the switching loss and minimize the overall torque ripple.

Further, in the present invention, the rectified torque ripple can be minimized by the opposite slope as the reference phase current, and the torque ripple due to the back EMF phase shift error can be reduced by the back EMF phase shift error compensator.

Furthermore, in the present invention, switching power loss can be controlled by hysteresis bandwidth.

1 is a timing diagram showing an ideal phase current ignition timing based on back EMF.
2 is a timing diagram showing misalignment between back EMF and phase current.
3 is a timing diagram showing hysteresis bands and pulses according to an error current according to the present invention.
4 is a block diagram showing a BLDC motor drive with a constant band hysteresis current controller with a back EMF phase shift error compensator in accordance with the present invention.
Fig. 5 is a timing diagram showing the relationship between the counter electromotive force and the phase current without a rectified phase error source.
6 is a timing diagram illustrating a relationship between a counter electromotive force and a phase current using a rectified phase error source.
7 is a timing diagram illustrating a relationship between a phase shift amount and torque ripple.
8 is a timing diagram showing torque ripple when the zero-crossing position is detected early.
9 is a timing diagram showing torque ripple when a zero-crossing position is detected late.
10 is a timing diagram showing the difference between the load torque and the actual torque when the zero-crossing position is detected early and the error is monitored by the integrator.
11 is a timing diagram showing the difference between load and actual torque when the zero-crossing position is detected late and the error is monitored by the integrator.
FIG. 12 is a timing diagram illustrating torque generated in a constant band hysteresis current controller under a phase shift condition of a 15 degree electric angle. FIG.
FIG. 13 is a timing diagram illustrating torque generated by a constant band hysteresis current controller as a counter electromotive force phase shift error compensator under a phase shift condition of a 15 degree electric angle.
14 is a timing diagram showing a measurement speed of a BLDC motor in a dynamometer.
FIG. 15 is a timing diagram showing torque generated in a constant band hysteresis current controller when only inaccurate zero-crossing detection.
16 is a timing diagram showing torque generated in a constant band hysteresis current controller with back EMF phase shift error compensator in case of inaccurate zero-crossing detection.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this process, the size or shape of the components shown in the drawings may be exaggerated for clarity and convenience of description.

In addition, terms that are specifically defined in consideration of the configuration and operation of the present invention may vary depending on the intention or custom of the user or operator. Definitions of these terms should be made based on the contents throughout the specification.

First, the state-space model of the BLDC motor will be described.

State-space models of BLDC motors are built and used for Matlab / Simulink simulations. The mathematical model of armature winding for a BLDC motor is expressed as follows.

Where R is phase resistance and V _an , V _bn and V _cn are terminal phase voltage references from neutral voltage. The counter electromotive force has an electrical angle of 120 degrees from one phase to another, and may be represented by Equations 18 to 20 below.

는 사다리꼴 함수,

는 회전자의 전기각이다.Where K _e is the counter electromotive force,

Is a trapezoidal function,

Is the electrical angle of the rotor.

Subtracting Equation 16 from Equation 15 and subtracting Equation 17 from Equation 16 can obtain a phase voltage as shown in Equations 21 to 23, respectively.

Since the sum of the phase currents i _A , i _B , and i _C is 0, Equation 22 is rearranged as follows.

The electromagnetic torque generated by the BLDC motor is calculated as follows.

or

Where T _e is the electromagnetic torque and w _m is the mechanical angular velocity of the motor. In the steady state, the electromagnetic torque is expressed as follows.

Where T _L is the load torque, J is the inertia of the shaft associated with the rotor, and β is the coefficient of friction. By the differential theorem, Equation 21, Equation 24, and Equation 27 are converted into the Laplace domain and can be expressed in the form of a state-space model as follows.

Equations 28 and 29 are used as a state-space model required to define the BLDC motor 30 to be controlled in the BLDC motor driving apparatus shown in FIG. 4.

Before describing the BLDC motor driving apparatus according to the present invention, the commutation phase shift error, torque and torque ripple will be described with reference to FIGS. 1 and 2.

In BLDC motor drive applications, various phase compensation techniques have been proposed to minimize torque ripple due to rectified back EMF phase shift error. If a rectified phase shift error occurs, the zero-crossing position as shown in FIG. 2 is misaligned.

Figure 1 shows the ideal phase current ignition timing based on back EMF. In this case, the rectified phase current must be injected after 30 degrees electric angle from the back EMF zero-crossing point. However, when erroneous back EMF zero-crossing detection occurs, the phase current ignition time and period shift exactly by the amount of back EMF zero-crossing detection error. This results in a misalignment between the back EMF and the phase current shown in FIG.

The torque equation may be rearranged by applying Equation 4 and Equation 23 to Equation 25 as follows.

However, if false back EMF zero-crossing detection occurs, back EMF is no longer constant but torque is reduced. The corresponding back EMF can be modified and expressed as follows for late back EMF zero-crossing detection.

는 역기전력의 기울기이며 모터 구동장치는 도 2와 같은 역기전력의 A 위상을 결정할 수 있다. 수학식 25에서 수학식 31 내지 수학식 33을 빼면 대응하는 토크(T_e)는 다음과 같이 계산된다.Where Δt is the amount of time delayed

Is the slope of the counter electromotive force and the motor driving device may determine the A phase of the counter electromotive force as shown in FIG. Subtracting Equations 31 to 33 from Equation 25, the corresponding torque T _e is calculated as follows.

Hereinafter, a compensation scheme for the rectified back EMF phase shift error according to the present invention will be described in detail with reference to FIGS. 3 and 4.

4 illustrates a BLDC motor driving apparatus having a constant band hysteresis current controller having a back EMF phase shift error compensator according to an exemplary embodiment of the present invention.

First, referring to FIG. 4, the BLDC motor driving apparatus according to the present invention includes a reference phase current generator 11, a constant band hysteresis current controller 12, a counter electromotive force phase shift compensator 13, an integrator 14, and an error generator 15. ), Load torque generator 16, angular velocity / speed converter 17, reference speed generator 18, back EMF generator 19, mechanical / electric angle converter 20, torque calculator 21, splitter 22 , State multiplexer 23, 28, mode selector switch 24, splitters 25a, 25b, summers 26, 27, and BLDC motors.

In FIG. 4, reference numeral 30 denotes a BLDC motor including a splitter 22, 25a, 25b, a summer 26, 27, a multiplexer 23, 28, a BLDC motor 29, and a counter electromotive force generator 19. This is for the purpose of easily simulating the characteristics of the motor using the Matlab / Simulink program, which is a design program for the BLDC motor 30.

The structure of the BLDC motor 30 is expressed based on the state-space model shown in Equations 28 and 29.

The present invention focuses on additional torque ripple due to commutation torque ripple and back EMF phase shift error. In the present invention, a constant band hysteresis current controller 12 is used to reduce commutation torque ripple. The constant band hysteresis current control technique is very simple and easy to implement. Unlike PID controllers that have significant switching power losses with a significant amount of torque ripple, constant band hysteresis current controller 12 can easily control the torque ripple amount and switching power losses with hysteresis bandwidth.

From the BLDC motor state space model 29, the three phase currents i _A , i _B , i _C , the machine angular velocity w _m and the rotational position of the motor rotor can be known. ) Is output to the splitter 22. Dual phase currents i _A , i _B , i _{C are} supplied from the splitter 22 to the torque calculator 21 through a multiplexer (MUX) 23 and at the same time a constant band hysteresis current controller 12. ) Is supplied as feedback phase current (i _A , i _B , i _C ).

The machine angular velocity (w _m ) and rotational angular velocity (rad) are applied to the counter electromotive force generator (19), and the counter electromotive force generator (19) outputs the machine angular velocity (w _m ) of the rotor to the machine angle / electric angle converter (20). and outputting the three-phase flux value in the torque converter 21, and generates and outputs a three-phase BLDC splitter (25a), the three-phase back electromotive force (e _a, e _B, e _C) to the motor state-space model (30) .

Various output signals generated from the BLDC motor 30 can be detected using, for example, a Hall sensor or a voltage detector.

)으로 변환하여 그 값을 일정 대역 히스테리시스 전류 제어기(12)에 공급한다.The machine angle / electric angle converter 20 converts the machine angular velocity (w _m ) of the rotor into an electric angle (

) And supply the value to the constant band hysteresis current controller 12.

The torque converter 21 is supplied to the three-phase current (phase current) (i _A, i _B, i _C) and three-phase output torque error generator 15 to calculate the (T _e) from the magnetic flux value.

In addition, the rotational angular velocity (rad) is converted from the angular velocity (rad) to the speed (rpm) in the angular velocity / speed converter 17, and then supplies the output speed (rpm) of the actual motor to the reference phase current generator (11). .

On the other hand, the error generator 15 is a desired load torque (T _L ) set by the user received from the load torque generator 16 and the output torque (T _e ) of the actual motor received from the torque calculator 21. Compare and output the error value. That is, the error generator 15 is the output torque (T _e), the load torque (T _L) is larger back EMF zero than - the values of the error value so as to different it is determined that rapid, reducing the speed at the time of crossing detection () If the output torque (T _e ) is smaller than the load torque (T _L ), it is determined that the phase is slow during the counter electromotive force zero-crossing detection in contrast to the above, so that the error value has a positive value to increase the speed. Is set.

The error value is supplied to the integrator 14 while being supplied to the BLDC motor 30 through the multiplexer (MUX) 28.

The integrator 14 receives the error value from the error generator 15, generates an integrated value for each preset sampling period, and outputs the integrated value to the counter electromotive force phase shift compensator 13.

The back EMF phase shift compensator 13 compensates the back EMF phase shift by increasing the output when the error value accumulated in the integrator is negative and decreasing the output when the error value is positive.

The counter electromotive force phase shift compensation method will be described in detail later with reference to FIGS. 5 to 16.

)를 출력한다. On the other hand, the reference phase current generator 11 serves as a speed PID controller, and receives a reference speed generated by the reference speed generator 18, that is, a speed value specified by the user, and receives the reference speed value. Current in the constant band hysteresis current controller 12 compared to the actual output speed (rpm)

)

)를 증가시키고, 실제 출력 속도(rpm)가 기준 속도보다 더 크면 기준 상 전류(

)를 감소시키는 제어가 이루어진다.That is, as a result of the comparison, if the actual output speed (rpm) is smaller than the reference speed, the reference phase current (

) And if the actual output speed (rpm) is greater than the reference speed,

Control is reduced.

), BLDC 모터(29)로부터 피드백 상 전류(phase current)(i_A,i_B,i_C), 기계각/전기각 변환기(20)로부터 회전자의 전기각(

), 역기전력 위상 편이 보상기(13)로부터 역기전력 위상 편이 보상값을 수신하여 BLDC 모터(30)에 대한 PWM(펄스 폭 변조) 출력 전압의 제어와 정류(commutation) 토크 리플을 감소시키는 제어를 실시한다.The constant band hysteresis current controller 12 receives a reference phase current from the reference phase current generator 11.

), The feedback phase current (i _A , i _B , i _C ) from the BLDC motor 29, the electrical angle of the rotor from the mechanical / electric angle converter 20 (

), And receives the back EMF phase shift compensation value from the back EMF phase shift compensator 13 to control the PWM (pulse width modulation) output voltage to the BLDC motor 30 and to reduce the commutation torque ripple.

The constant band hysteresis current controller 12 may control the PWM output voltage by the constant band hysteresis scheme shown in FIG. 3 or control the output voltage by the PID scheme.

In the present invention, the mode selection switch 24 is set in advance to control the output voltage in a constant band hysteresis scheme to output to the motor.

Hereinafter, the hysteresis-type PWM output voltage control using the constant band hysteresis current controller 12 according to the present invention will be described with reference to FIG. 3.

)와 함께 측정되고 비교된다. 정류 토크 리플은 동일하지만 반대 정류 상 기준 전류에 의해 최소화된다. 피드백 상 전류와 기준 상 전류 사이의 오차(error)는 사전 설정된 히스테리시스 대역(hysteresis band)을 갖는 비교기로 공급된다. 상위 히스테리시스 대역(Upper HB)과 하위 히스테리시스 대역(Lower HB)은 히스테리시스 대역 범위 '2h' 내에서 오차가 비교되도록 제로 레퍼런스에서 'h'를 더하고 빼서 사전 설정된다. Certain hysteresis band feedback phase current from the current controller (12) (phase current) ( i A, i B, i C) is based on a current controlled by the speed of the PID controller (reference phase current) (

Are measured and compared. The rectified torque ripple is the same but minimized by the opposite rectified phase reference current. The error between the feedback phase current and the reference phase current is fed to a comparator with a preset hysteresis band. The upper hysteresis band (Upper HB) and the lower hysteresis band (Lower HB) are preset by adding and subtracting 'h' from the zero reference so that the error is compared within the hysteresis band range '2h'.

3 shows how the speed change falls in the upper and lower hysteresis bands (Upper HB, Lower HB) and the hysteresis band range. If the current current error exceeds the upper hysteresis band (Upper HB), the + V _d pulses drop to -V _d pulses so that the output voltage to the motor decreases in pulse width. Contrary to the above, when the current error falls below the lower hysteresis band Lower HB, the + V _d pulse is given so that the output voltage to the motor increases in the pulse width.

)를 따라 유지한다. 이 방법을 사용하면 피드백 상 전류 및 기울기는 기준 상 전류 및 기울기를 따라간다. 그러나, 일정 대역 히스테리시스 전류 제어 기법은 'h'의 설정 값이 스위칭 동작의 빈도 및 토크 리플의 양을 결정하기 때문에 몇 가지 딜레마가 있다. 따라서, 토크 리플의 양을 적게 하기 위해서는 더 큰 스위칭 손실을 감수해야 한다.The feedback phase current i _A , i _B , i _C is the reference phase current (where the amount of error is limited to the hysteresis bandwidth)

To follow). Using this method, the feedback phase current and slope follow the reference phase current and slope. However, the constant band hysteresis current control technique has some dilemma since the set value of 'h' determines the frequency of the switching operation and the amount of torque ripple. Therefore, in order to reduce the amount of torque ripple, a larger switching loss must be taken.

In the present invention, in addition to the rectified torque ripple, overload torque ripple occurs due to the back EMF zero-crossing error due to the back EMF zero-crossing detection. The constant band hysteresis current controller 12 alone cannot guarantee minimization of the total torque ripple. Even if the feedback phase current well follows the reference phase current, additional torque ripple always occurs when there is a back EMF phase shift offset.

The only simple solution to minimize torque ripple is to correct the phase shift with a back EMF phase shift error corrector 13. The amount and shape of the torque ripple depends on the amount of phase shift and the direction of back EMF phase shift. Accordingly, in the present invention, by adopting a simple integrator 14 as the phase integration error monitor, the amount and direction of the counter electromotive force phase are monitored and thus the detected phase shift error is compensated.

In the following, the simulation is performed to check the effects on the counter electromotive force phase shift, error compensation, and torque ripple reduction of the BLDC motor driving apparatus according to the present invention configured as described above, and introduces the experimental results.

Constant band hysteresis current control using the back EMF phase shift compensator algorithm for BLDC motor drive was developed and simulated using the Matlab / Simulink program. In this simulation, a DC voltage of 800V was applied at 5N.m load torque and the reference speed was set at 1000rpm. The state space model of the BLDC motor 30 is implemented as shown in FIG.

The parameters of the BLDC motor used in the simulation are shown in Table 1 below.

parameter Set value Stator Resistance (Ω) 0.0485 Stator phase inductance (H) 0.0085 Magnetic flux chain professor (V.s) 0.1194 Inertia (J) 0.0027 Number of pole pairs 4

The BLDC motor used in this simulation has the parameters shown in Table 1 above.

The relationship between back EMF and phase current from the closed loop performance of a BLDC motor drive using constant band hysteresis current controller 12 without commutation phase shift error is shown in FIG. 5.

However, when the rectified phase shift error source interferes, the phase current is delayed as shown in FIG. The phase current is observed to increase to compensate for the reduced torque due to the back EMF phase shift error, which is shifted exactly by the amount of zero-crossing point detection delay.

In FIG. 7, the phase shift was not applied until 0.05 seconds, the electric angle of 5 degrees was applied in 0.1 second, and then the electric angle of 5 degrees was applied again, thereby changing the electric angle of 10 degrees in total. Depending on the amount of phase shift, an increase in the amount of torque ripple concluded that the amplitude of the torque ripple depends on the amount of phase current shift.

However, it is difficult to determine whether the counter electromotive force zero crossing position is detected early or late. To compensate for back EMF phase shift errors, the direction of the phase current must also be indicated. In the present invention, the shape of the torque ripple is closely analyzed because the shape changes in accordance with the phase shift direction. The corresponding torques caused by the 15 degree electrical angle phase shift in the negative and positive directions are shown in FIGS. 8 and 9, respectively.

As shown in Figures 8 and 9, different distortions of the torque ripple are observed for phase shift errors in the negative and positive directions, which can be used to identify the direction of the phase shift. The error between the load torque and the actual output torque is indicated with the output of the integrator 14 of FIGS. 10 and 11.

By observing the output of the integrator 14, it is possible to determine the direction of the phase shift. If the output of the integrator 14 has a concave shape as shown in Fig. 10, early zero-crossing position detection is assumed.

On the other hand, when having a convex shape as shown in Fig. 11, delay zero-crossing position detection is assumed. 12 and 13 show the reduction in torque ripple achieved by the constant band hysteresis current controller 11 and the back EMF phase error compensator 13.

In this experiment, a hysteresis brake dynamometer (BHD-144) manufactured by Valid Magnetics is used to analyze torque ripple due to back EMF phase shift error. Table 2 below shows a typical test setup for measuring torque ripple using a dynamometer.

parameter value Speed (rpm) 12000 Cooling mode air blower Kinetic power natural convection (5 minutes) (W) 2000 Power with blower (5 minutes) (W) 3500 Kinetic Power Natural Convection (Continuous) (W) 700 Power with Blower (Continuous) (W) 3000 Load torque (N.m) 13.4 Torque at rated current (Kgcm) 140 Data update rate (Hz) 5 Accuracy rating ± 1%

Table 2 shows the specific parameters of the hysteresis brake dynamometer (BHD-144). Torque ripple was measured at a speed of 360 rpm with varying load torque as shown in FIG.

FIG. 15 shows the torque measured from constant band hysteresis current controller 12 with only load torque varying from 0.5 Nm to 1.5 Nm under incorrect zero-crossing detection. Experiments started with 0.5 Nm load torque, and an additional 0.5 Nm load torque was added every 5 seconds resulting in a total of 1.5 Nm load torque.

16 shows the measured torque of a constant band hysteresis current controller 12 with a back EMF phase shift error compensator 13.

Unlike the torque measured when using only the constant band hysteresis current controller 12, the counter electromotive force phase shift error compensator 13 according to the present invention is effective in reducing the torque ripple caused by the reverse electromotive force phase shift error. The proposed circuit is suitable for minimizing torque ripple during the commutation period.

As described above, the present invention proposes a constant band hysteresis current controller using a back EMF phase shift compensator and shows that it is appropriate to reduce the torque ripple caused by the rectified back EMF phase shift error and the rectified torque ripple.

 The present invention can be applied to a BLDC motor driving device using a constant band hysteresis current controller having a counter electromotive force phase shift compensator to reduce the torque ripple caused by the rectified counter electromotive force phase shift error and the rectified torque ripple.

11: Reference Phase Current Generator 12: Constant Band Hysteresis Current Controller
13: Back EMF Phase Shift Compensator 14: Integrator
15: error generator 16: load torque generator
17: angular velocity / speed converter 18: reference velocity generator
19: counter electromotive force generator 20: machine angle / electric angle converter
21: Torque Calculator 22: Splitter
23, 28: MUX 24: mode selector switch
25a, 25b: splitter 26, 27: summer
29: BLDC motor state space model 30: BLDC motor

Claims (5)

A BLDC motor driving device for driving a three-phase BLDC motor based on the three-phase current of the three-phase BL (DC) brushless DC motor, the angular velocity of the machine and the rotational angular velocity of the rotational position of the motor rotor
A machine angle / electric angle converter for converting and outputting the machine angular velocity into an electric angle;
An angular velocity / speed converter for converting the rotational angular velocity into a speed to output an output speed of a motor;
A reference phase current generator for generating a reference phase current by comparing the actual output speed of the motor with a reference speed generated by a reference speed generator; And
Using a constant band comparator having a constant hysteresis band, a current error is generated by comparing the feedback three-phase current with a reference phase current, and comparing the current error with upper and lower hysteresis bands to PWM (pulse width). Modulation) constant-band hysteresis current controller for controlling the pulse width of the output voltage. The method of claim 1,
And the reference phase current generator increases the reference phase current if the actual output speed is less than the reference speed, and decreases the reference phase current if the actual output speed is greater than the reference speed. The method of claim 1,
The three-phase current _{(phase current) (i A,} i B, i C) and a torque calculator for calculating and outputting the output torque (T _e) from the three phase flux values;
An error generator for outputting an error value by comparing the load torque generator a desired load torque set by the user received from the (load torque) (T _L) and the output torque (T _e) of the actual motor received from the torque converter;
An integrator that receives an error value from the error generator and generates an integrated value for each preset sampling period; And
A counter electromotive force phase shift compensator for compensating the counter electromotive force phase shift by increasing the output when the error value accumulated in the integrator is a negative value and decreasing the output when the error value is a positive value;
When the output torque is greater than the load torque, the error generator determines that the phase is high when the counter electromotive force zero-crossing is detected, so that the error value has a negative value to reduce the speed.
And if the output torque is smaller than the load torque, determine that the phase is slow upon counter electromotive force zero-crossing detection, and set the error value to have a positive value so as to increase the speed. The method of claim 1,
And the constant band hysteresis current controller generates a current error comparing the feedback phase current with the reference phase current using a constant band comparator having a constant hysteresis band. The method of claim 4, wherein
If the current error exceeds the upper hysteresis band (Upper HB), the pulse width of the PWM output voltage is reduced,
BLDC motor driving device to increase the pulse width of the PWM output voltage when the current error falls below the lower hysteresis band (Lower HB).

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