Transcript 下載/瀏覽

Robot and Servo Drive Lab.
Sensorless Speed Control of BLDC Motor Using
Six-Step Square Wave and Rotor Position Detection
2010 the 5th IEEE Conference on Industrial Electronics and Applications
(ICIEA), No. 1538-1362, 15-17, June 2010, By Tzuen-Lih Chern, Ping-Lung
Pan, Yu-Lun Chern, Der-Min Tsay
Professor: MING-SHYAN WANG
Student: CIH-HUEI SHIH
Department of Electrical Engineering
Southern Taiwan University of Science and Technology
2016/7/14
Outline






Abstract
Compare references
The Principle of proposed sensorless control
a)
System Block
b)
Zero Crossing Point
c)
Design proposed controller
Experiment Result
a)
Block Diagram
b)
Initial Position
c)
The phase current waveform
Conclusion
Excursus
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
2
Abstract

This paper presents a brushless DC motor (BLDCM) control system that
does not require Hall sensor and speed encoder for an air conditioner fan
motor. Using low cost circuits, the zero-crossing points are detected to
estimate the commutated timing and speed information.

Hall element shortcoming can therefore be eliminated. A modified six-step
square wave pattern with pulse-width modulation is developed to simplify
the conventional coordinate transformations technique. To verify the
proposed method, a prototype fan motor controller is constructed and
tested. Experimental results show that the proposed method has high
efficiency and good performance.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
3
Compare references





1. Simple position sensorless starting method for brushless DC motor
2. Sinusoidal current drive system of permanent magnet synchronous
motor with low resolution position sensor
3. Digital signal processing-based sensor-less permanent magnet
synchronous motor driver with quasi-sine pulse-width modulation for airconditioner rotary compressor
4. A Novel Microcontroller-based Sensorless Brushless DC (BLDC) Motor
Drive for Automotive Fuel Pumps
5.Selection of electric motor drives For electric vehicles
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
4
The Principle of proposed sensorless control

The block diagram of proposed sensorless BLDCM control system is
shown in Fig.1. There are five sub blocks in this system, as following:
(1). The back-EMF detecting circuit and the speed estimating block.
(2). A set of Proportional-Integral (P-I) controller.
(3). A set of modified six-step square-wave model.
(4). The Power inverter has six power switches that are driven by the PWM
duty ratio.
(5). The current feedback control loops.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
5
System Block
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
6
Zero Crossing Point

Considering an operation period, when the phases u and v are excited at
this moment. The current i flow through phase u and v to the ground, here
the phase w is floating now.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
7

From the view point of phase U, the voltage equation of motor model is
given by:
𝑉𝑛 = 𝑉𝑑𝑐 − 𝑉𝑚𝑜𝑠 − 𝑖𝑅 − 𝐿

From the view point of phase V, the voltage equation of motor model is
given by :
𝑉𝑛 = 𝑉𝑚𝑜𝑠 + 𝑖𝑅 + 𝐿

𝑑𝑖
− 𝑒𝑢 … (1)
𝑑𝑡
𝑑𝑖
− 𝑒𝑣 … (2)
𝑑𝑡
The equation of terminal voltage Vw for phase W on BLDCM can be
written as
𝑉𝑑𝑐 3
𝑉𝑤 = 𝑉𝑛 + 𝑒𝑤 =
+ 𝑒𝑤 … (3)
2
2

From (3), one can see that the Vw is the combination of voltage Vdc and Vn
.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
8

The typical BLDCM phase voltage waveform and ZCP signals. The ZCPs
occur while the back-EMF voltage ew is zero.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
9

Base on the electrical criteria of BLDCM described in [1],[2] and [6], the
torque equation of BLDCM can be wrote as：
Te =

Eu Iu +Ev Iv +Ew Iw
ω
…(4)
Conventionally, the conducting interval of three-phase for BLDCM control is
designed as 120 electrical degrees. From (4), one can see that if motor phase
current in phase with back- EMF voltage, the system efficiency would be highest.
For finding the optimal conducting angle, in this study, the conducting timing of six
power switches in designed inverter will be deal with 0 delay, 15 delay, and 30
delay. Fig. 4 describes the desired displacement for three type angle delay. The sine
waves in the figures indicate three phase back-EMF waveform, and the square
waves explain the conducting states of six power switches.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
10
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
11
Design proposed controller

Due to the back-EMF can not be detected in stand-still state. To starting the
motor in static state, the fixed-phase starting strategy is proposed. First step
in the starting process is, providing a short period pulse for a given phase
to rotate the rotor to reach a fixed position, then, driving the motor with
preset voltage and frequency, which will run the rotor with a fixed
direction and speed. Through 0.5 seconds, the motor speed reaching 500
rpm, then the system is transferred to back-EMF detected mode by DSP
program. In this mode, the motor run without Hall sensors and the closedloop speed control will be started.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
12

The Back-EMF sampling circuit. The input voltage of analog to digital
(ADC) in DSP is limited at 3.3V full scale. The sampling factor of backEMF voltage was designed about 50 times decay. The left hand terminal in
Fig.5.is connected to the motor phase winding directly. The right hand
terminal is connected to DSP input.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
13

For evaluating the corrected timing of commutated point in the Back-EMF,
the terminal voltage waveforms of six-step drive system are measured and
shown in Fig 6. The 4th channel indicates the terminal voltage of W phase.
The waveforms of 1st, 2nd, and 3rd channel show three phase Hall signals
U, V and W respectively. From the figure, one can see that the timing of
zero-crossing points exist in the red circle mark areas. For saving the
process resource,
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
14

For increasing the system power efficiency, the inner current loops are
designed to control motor current in phase with the Back-EMF voltage.
Figure shows the one of three current control loops in control system. The
phases current of motor in control system are sensing by the Hall current
sensors.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
15
Experiment Result

To verify the feasibility of propose method, an experiment system base on
TI TMS320LF2407A digital processor is constructed, the system block
diagram shows in Fig 8. The various testing will be arranged for proving
the proposed method performance. The specification of BLDCM is listed
in table 1. The motor have Hall sensors, the purpose of these sensors is
only for monitoring the situation of rotor position. In this scheme, the
control gain for Kp and Ki are set to be 4000 and 600 respectively. The
PWM frequency is set as 15 kHz.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
16
Block Diagram
Items
Specifications
Rated Voltage
300VDC
Rated Power
500Watt
Rated Speed
3000RPM
Rated Torque
16.3Kgf-cm
Resistance
2.37Ω
Inductance
12.8mH
Table I. Specifications of tested motor
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
17
Initial Position

Fig 9 is the speed response curve of proposed sensorless control. In this
test, the speed command is set at 1000 rpm. The speed values showed in
scope is directly from DSP speed output and it had confirmed by
tachometer. The curve shows that the motor has good speed tracking.
Figure 10 shows the comparison between estimated zero-crossing points
and three phases Hall signal. The waveforms show that all the estimating
commutated points are close to Hall signals.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
18

Fig. 11 shows the Hall signals and the phase current. The tested speed is set
to be fixed at 1000 rpm. The motor performs (a) 0° delay, (b) 15 ° delay,
and (c) 30 ° delay. The amplitude of the phase current showing in (a) is
peak to peak 2.7 Amp, (b) is peak to peak 1.7 Amp, and (c) is peak to peak
1.3 Amp. Here the scale of phase current in the scope is proportioned to the
voltage of current sensor output.
2016/7/14
(a)
(b)
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
(c)
19
The phase current waveform
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
20
Conclusion

A new sensorless BLDCM driving system based on TI TMS320LF2407A
DSP has been successfully implemented and tested in this paper. The
theorem analysis and test results shown the proposed system have simple
structure then conventional sensorless control methods. The proposed ZCP
detecting method use only simple components for rotor position and speed
detecting that satisfy the home electric appliance applications. For reducing
power consumption, the current control loops were added in proposed
speed control system. Finally, a speed changeable air conditioner fan motor
control system was build to prove the feasibility. The measured results
show that the propose system has good performance.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
21
System Block
Fo(故障信號)
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
22
Phototransistor Coupler Circuit
PWM SW

2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
23
IPM-PS21997

Department of Electrical Engineering
Southern Taiwan University of Science and Technology
RS1為Shunt電阻，當電壓
大於0.48V時，則IPM內部
啟動保護，為了防止雜訊
帶來的干擾，則需添加
1.5~2.0uF的濾波電路，
Shunt電阻旁的佈線越短越
好
24
Power Circuit
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
25
Motor parameter
馬達型號(Model number)
BL90LM0D8R00230500
額定電壓(Rated Voltage)
220VAC
無載轉速(No Load Speed)
4500 ±5% rpm
無載電流(No Load Current)
0.7 ±10% A
轉向(Direction of Rotation)
C.W
額定功率(Rated Power)
590W
額定轉矩(Rated Torque)
16.0kg-cm
額定電流(Rated Current)
5.0 ±5%
額定轉速(Rated Speed)
3600 ±5% RPM
線間電阻(L-L Resistance)
4.3 ±5% Ω
耐壓測試(Hi-Pot)
1000VAC/1mA/1sec.
絕緣測試(Insulation Test)
500VDC/50MΩ min.
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
26
Flow chart (Main)
Dspic30F4011

數位/類比 IO規劃決定此系統晶片的數位IO和類
比IO
數位/類比
IO規劃

數位IO牽涉到邏輯電位判別，以5V 30F4011而
例，只要電位大於2.5V，則邏輯準位為1；反之
小於2.5V，則邏輯準位為0，一般數位IO內部為
Push-Pull結構，故輸出電流最大為25mA；如果
為Open-Drain結構，則輸出電流非常小，故外部
需要有Pull-High電阻至電源，而此架構好處在
於不同高低電位之間的轉換，常用於I2C的內部
架構

類比IO主要決定使用ADC功能時所選用的腳位
，假若這個功能沒設定好，則ADC功能無法使
用

ADPCFG = 0xFF3F; RB6、RB7為類比IO
使用
實驗室驅動器
？
Yes
ADC
Function
No
Timer
Function
CN_Capture
Function
Hall_Detect
Function
2016/7/14
PWM
Function
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
27
Flow chart (Sub)
CN_Capture
建立六步方波
換相Table表
Case 5
Case 1
Case 3
Case 2
Case 6
Case 4
UV
WU
WV
UV
UW
VW
0x1027
0x0137
0x011E
0x041B
0x0439
0x102D
表1.Phase_State
No
中斷是否發生
?
Yes
Speed_Measure
Function
Hall_Detect
Function
輸出兩相PWM
訊號
2016/7/14
結束
圖2.Hall Sensor Perpherial Circuit
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
28
Flow chart (Sub)
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
29
Flow chart (Sub)
Speed_Measure
ADC
讀取Timer
計數暫存器
啟動自動轉換
根據轉速公式
求得轉速
ADC
Function
圖3.Current Sensor Perpherial Circuit
A/D轉換完成
？
No
Delay ≥ 154ns
Yes
讀取2路A/D數
值
根據旋轉座標
求得Id、Iq
數值計算得到
16進制值
結束
轉換實際電流
值
結束
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
30
Terminal Voltage
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
31
Phase Current
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
32
PID Control


PID控制器（比例-積分-微分控制器），由比例單元P、積分單元I和微分單元D組成。
通過Kp，Ki和Kd三個參數的設定。PID控制器主要適用於基本上線性，且動態特性不隨
時間變化的系統。
PID控制器是一個在工業控制應用中常見的反饋迴路部件。這個控制器把收集到的數據
和一個參考值進行比較，然後把這個差別用於計算新的輸入值，這個新的輸入值的目
的是可以讓系統的數據達到或者保持在參考值。PID控制器可以根據歷史數據和差別的
出現率來調整輸入值，使系統更加準確而穩定。
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
33

在實驗上採用兩種不同PI控制器計算作法，一種是隨機取樣時間；反
之固定取樣時間1ms，透過兩種輸出結果我們可確認每60度取得新轉
速時作PI控制，亦或者在0~60度間轉速值還未更新時作PI控制之間的
差異性。
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
34
Experiment


(a)使用隨機取樣時間作PI控制，啟轉5%、速度命令400rpm
(b)使用固定取樣時間作PI控制，啟轉5%、速度命令400rpm
(a)每60度_Ki_Error = 919，Kp=0.15、Ki=0.25
(b)1ms_Ki_Error = 28015，Kp=0.015、Ki=0.015
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
35
Discussion

從實驗結果圖可以得知實驗(a) Ki的總誤差量小，而實驗(b) Ki總誤差
量卻非常龐大，代表說當轉速還未更新時，Duty增減量會因為速度命
令減去上一比速度值會有累加數筆的情形；反之，如實驗(a)在每60度
得到轉速時作一次PI控制，此方法的取樣時間比實驗(b)還長，除非本
身馬達的性能非常良好，否則取樣時間一拉長，速度震盪也有可能會
非常大。
2016/7/14
Department of Electrical Engineering
Robot and Servo Drive Lab.
Southern Taiwan University of Science and Technology
36