According to the experiment result, we can find that the response is faster and the overshoot may exist when Ki become decrease.
In the experiment, we have some problems when we implement the BLDC motor control and make it failure. The failure analysis list as following:
1. Isolation
Fig 5.2 shows the hardware setup. At first, we did not add the isolation transformer, so the computer’s ground and the inverter’s ground are the same. It will cause damage to computer and microcontroller.
Besides, the primary and secondary’s ground of flyback converter in the inverter are conncected, it will also ruin computer or microcontroller.
2. PWM output waveform
When we set up the PWM output pin by TIOR (Timer input/output control register), the output pins state are right at beginning, but after four to five times of switching PWM output pins state, the output waveforms are error. This is caused by wrong setting so that we ruin many IGBT module in the inverter. So the pins state need to check carefully.
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3. Priority
In the experiment, the interrupt of checking hall signal and doing commutation must be the highest priority in the interrupts we used, if this interrupt be affected, we have chance to break IGBT module. Table 6.1 shows the priority of internal interrupt, so TGIA_0 interrupt is used for checking hall signal.
The MCU we used is powerful, it can be used to develop more complex control method in BLDC motor such as direct torque control.
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Reference
[1] Y. S. Lai, F. S. Shyu, and Y. H. Chang, “Novel loss reduction pulse width modulation technique for brushless dc motor drives fed by MOSFET inverter”, IEEE Trans. Power Electron., vol. 19, no. 6, pp. 1646-1652, Nov. 2004.
[2] K. Y. Cheng and Y. Y. Tzou, “Design of a sensorless Commutation IC for BLDC Motors”, IEEE Transactions of Power Electronics, vol.18, no.6, pp.1365-1375, November 2003.
[3] H. C. Chen, Y. C. Chang, and C. K. Huang, “Practical sensorless control for inverter-fed BDCM compressors,” IET Proc. Electric Power Applications, vol.
1, no. 1,pp. 127-132, Jan. 2007.
[4] 徐舶強, 無感測直流無刷馬達之驅動電路設計, 國立交通大學機械工程學 系所, 碩士論文, 2008
[5] 吳宇中, 使用微控制器SN8P1708晶片實現三相永磁馬達之控制, 國立交通 大學電機與控制工程系所, 碩士論文, 2005
[6] 賴逸軒, 以DSP為基礎發展永磁同步馬達使用線性型霍爾感測器與無感測 控制方法, 交通大學電機與控制工程系所, 碩士論文, 2005
[7] 卓淑婷, 直流無刷馬達無感測器驅動之分析, 交通大學電機與控制工程系 所, 2009
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Table
Step Electrical angle Phase current Hall sensor Switch on
1 100 Q5, Q0
2 101 Q3, Q0
3 001 Q3, Q4
4 011 Q1, Q4
5 010 Q1, Q2
6 110 Q5, Q2
Table 2.1 120 degree six-step square commutation table
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Output Pins
Channel Registers PWM Mode 1 PWM Mode 2
0 TGRA_0 TIOCA0 TIOCA0
TGRB_0 TIOCB0
TGRC_0 TIOCC0 TIOCC0
TGRD_0 TIOCD0
1 TGRA_1 TIOCA1 TIOCA1
TGRB_1 TIOCB1
2 TGRA_2 TIOCA2 TIOCA2
TGRB_2 TIOCB2
3 TGRA_3 TIOCA3 TIOCA3
TGRB_3 TIOCB3
TGRC_3 TIOCC3 TIOCC3
TGRD_3 TIOCD3
4 TGR4A_4 TIOCA4 TIOCA4
TGR4B_4 TIOCB4
5 TGRA_5 TIOCA5 TIOCA5
TGRB_5 TIOCB5
Table 3.1 PWM output registers and output pins
MD2 MD1 MD0 FWE LSI state after Reset end
1 1 1 0 Advance Mode
0 1 1 1 Boot Mode
Table 4.1 Two Mode correspond to their pins state respectively
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Table 4.2 Digital operator’s protocol
31
5. data
Digital operator → MCU (6 bytes) 0x 10 70 10 01 DC F 3 MCU → Digital operator (46 bytes)
0x 10 70 10 53 00 00 00 00 00 00 00 00 53 39 45 2D 30 35 34 33 20 20 20 20 20 20 20 20 55 31 2D 30 31 3D 20 20 30 2E 30 30 20 48 5A 20 D0 0F
Table 4.2 Digital operator’s protocol (continue)
Operator to MCU
Start code 1 Start code 2 DATA 1 DATA 2 CRC16_LB CRC16_HB MCU to Operator
Start code 1 Start code 2 LED_Ctrl LED_Data 0x00 0x00 0x00 0x00 LCD_Ctrl1 LCD_Ctrl2 LCD_Line1 LCD_Line2 CRC16_LB CRC16_HB
Table 4.3 Digital operator’s data format
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Motor Model No. AM750M
Input voltage 220V 10%
Input frequency 50/60 Hz
Max. input current 11.4 A
Motor phase 3
Rated torque 70 kg-cm
Motor insulation/
Max. working TEMP
B Class (130 C/266 F)/Max.
100 C/212 F
Motor weight 8.0 kg
Table 4.4 The specification of BLDC motor
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Type: RM-1000
Range 10 rpm ~100,000 rpm
Basic Accuracy +/- 0.01% +/- 1 dgt
Resolution 0.1 rpm
Sample rate 1 sec.
Measuring distance 50mm to 200m
Max distance 300mm
Recall Max value, Min value
Data hold Stop measurement and data hold
Time base 12.0MHz quartz crystal
Circuit High speed microcomputer
Range selection Automatic
Battery Four 1.5V batteries (AA UM-3)
Low battery indicator Red LED display Operation temperature 0 to 50 degree C
Table 5.1 Specification of tachometer
Table 5.2 Specification of Adlee driver
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Table 6.1 Internal priority of MCU
35
Table 6.1 Internal priority of MCU (continue)
36
Figure
Fig 2.1 The structure of BLDC motors
I
B d
+ _
VH
Fig 2.2 The Hall effect
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Fig 2.3 Schematic of the inverter and motor
Fig 2.4 Six-step sequences waveforms
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Step 1
Step 2
Step 3
Fig 2.5 The procedure of the commutation
39
Step 4
Step 5
Step 6
Fig 2.5 The procedure of the commutation (continue)
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Fig 2.6 The equivalent model of a BLDC motor
E
Fig 2.7 A BLDC motor equal circuit
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Fig 3.1 Main program flowchart
42
Fig 3.2 TGIA0 interrupt flowchart
43 H1
H2 H3
1 hall step or 1 pulse
Fig 3.3 Hall signal
Fig 3.4 Close-loop control block diagram
Fig 4.1 The structure of system
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Fig 4.2 The HD64F2612F340 chip’s pin arrangement
Fig 4.3 The layout of MCU circuit
45
Fig 4.4 MAX232CPE
Fig 4.5 BLDC motor
46
Fig 5.1 Inverter
Fig 5.2 Hardware setup
47
Fig 5.3 Six-step waveform
48
Fig 5.4 Hall signal’s waveform
Fig 5.5 Speed error
49
Fig 5.5 Speed error (continue)
Fig 5.6 Speed response without load at 1000 rpm
50
Fig 5.7 Speed response without load at 3000 rpm
Fig 5.8 Speed response with load at 500 rpm