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AN1498 APPLICATION NOTE
DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACE BOARD WITH THE ST92141 MCU
By Motor Control Competence Center
INTRODUCTION
This application note describes a Three Phase AC Inverter control board capable of driving discrete IGBTs directly. The board edge connections allow it to be directly plugged into the Power Board next to the power switches. This particular system split gives several advantages: - Improves the compactness and modularity of the whole system - Keeps the power away from signals and reduces parasitic coupling and noise sensitivity - Makes the power stage layout easier as well as compliance to norms - Makes the system design faster and future evolution easier The board features a powerful microcontroller and all the circuits needed to interface with the power switches and the environment. A large C software library allows you to design an AC motor control application quickly and easily.
AN1498/0102
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Table of Contents
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 CONTROL BOARD FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3 DC ELECTRICAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4 AC ELECTRICAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5 ST92141 PLATFORM SCHEMATIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6 ST92141-PLATFORM MECHANICAL DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 7 CONNECTION DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 8 TYPICAL APPLICATION: AC MOTOR DRIVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 9 SYSTEM VIEWS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 10 WASHER MOTOR DRIVE DEMONSTRATION SOFTWARE . . . . . . . . . . . . . . . . . 11 10.1 ST92141 SOFTWARE LIBRARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 10.2 ST92141 DEVELOPMENT TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 10.3 HOW TO RUN THE SOFTWARE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
10.3.1 Wash mode 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 10.3.2 Wash mode 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 10.3.3 Spinning mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.4 FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
10.4.1 Soft Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.2 Ramp-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.3 Sustain speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.4 Decrease speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.5 Motor stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.6 Voltage limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.7 Slip regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.8 Speed measurement protection / locked rotor . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.9 Unbalancement measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.10 Heatsink over-temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.11 Thermal monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.12 DC bus voltage supervision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.13 Input power supervision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.14 Motor over-current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.15 Watchdogs (main watchdog and peripheral watchdogs) . . . . . . . . . . . . . . 21 . . .. 14 15 15 16 16 16 16 16 16 16 17 17 17 18 18
10.5 FUNCTION LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
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DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACING BOARD...
1 CONTROL BOARD FEATURES
s s s s s s s s s s s s s s s s s
Three phase AC inverter control & interfacing Direct plug-in to Power Board 600V maximum line voltage rating Thermal monitoring and protection via external sensor Centralized instantaneous over-current protections Centralized average over-current protection Low side & high side driver under-voltage protection Switching frequency from 1kHz to 20kHz Up to eight general purpose digital I/Os with pull-ups/pull-downs and filtering Up to four general purpose A/D inputs Wide speed range tachometer input with interfacing Hardware SPI interface Software SCI or I2C interfacing capability EEPROM data storage capability Comparator input for external protection 400mA sourcing & 650 mA sinking current capability Features ST92T141K4M6, L6386D, LM358D, M95040
2 ABSOLUTE MAXIMUM RATINGS
Symbol Vline V15 VDD AVDD VIN VAIN dVout/dt Vcin Tstg T cop Parameter DC BUS voltage 15V DC supply voltage 5V DC supply voltage A/D converter analog reference Input voltage (digital I/O pins) Analog input voltage Allowed output slew rate Comparator input voltage Storage temperature Operating Temperature Value -0.3 to +600 -0.3 to +18 -0.3 to +6.5 Up to VDD +0.3 -0.3 to VDD + 0.3 Ground to AVDD 50 -0.3 to V15 + 0.3 -40 to +150 -40 to +85 Unit V V V V V V V/nsec. V C C
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DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACING BOARD...
3 DC ELECTRICAL CHARACTERISTICS
(Tamb = 25C unless otherwise specified)
Symbol Vi Parameter Logic input voltage threshold J10,11,13,15,16,19,20,22,24,25,27,28 Test Conditions VDD = 5V low high Min Typ Max Unit 0.8 3.5 13 4.5 10.7 8.8 -10 0.460 300 500 3.4 100 uA V
Ii Vline V15 VDD Vccth1 Vccth2 Vcchys Vio Iio Vref Iso Isi VLVDR VLVDF
Logic input current No pull-up, no pull-down J10,11,13,15,16,19,20,22,24,25,27,28 DC BUS voltage 15V DC supply voltage 5V DC supply voltage Driver Under Voltage turn-on threshold Driver UV turn-off threshold Driver UV hysteresis Comparator input offset voltage Comparator input bias current Comparator reference voltage High/low side driver short-circuit source current High/low side driver short-circuit sink current Reset release threshold Reset generation threshold
580 V 15 17 V 5 5.5 V 12.9 V 10.7 V 2 V +10 mV 0.2 uA 0.5 0.540 V 400 650 4.2 mA mA V V
4 AC ELECTRICAL CHARACTERISTICS
(Tamb = 25C unless otherwise specified)
Symbol IDDRUN IDDWFI IDDLPWFI Freq Parameter Board run mode bias current Board WFI mode bias current Board low Power WFI mode bias current Recommended switching frequency Test Conditions Min 1 Typ Max Unit 60 mA 25 mA 12 mA 20 kHz
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DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACING BOARD...
5 ST92141 PLATFORM SCHEMATIC
The values given are typical values only, and must be adapted to your specific application.
+15V C46
8
100nF
3+ 24
IC5A LM3 58D 1 5+ 6C45 1nF
IC5B LM3 58D 7 34 pins co nnector 44 s pace s used R56 1.5K R 55 1.5 K
1% 1%
+5V
+5V
R 52 33. 2K
R1 10K
TACHO METER
R2 10K
R53 750R
1%
1%
R5 4 47K
1.90 5mm pin to pin sp acing C1 C40 470nF 470nF
16V 16V
D 26 BAS16 LSIC1 J30 J19 +15V HSIC1 1 2 3 4
R3 82R R5
J16 J17 C2 100nF
R4 10K Q7 BC817 -25 D1 BAS16 D2 BAS16 C3 R6 100nF 100R U2 +5V M9504 0 1 2 +5V R 10 100K R1 1 100K R1 2 100K R13 100K R 14 100K 3 4 S Q W VCC HOLD CK 8 7 6 100nF 5 C3 9 +5V R shun t
IC1 L6386D LIN VBOOT SD HIN VCC DIAG CIN GND HVG OUT NC NC LVG GND 14 13 12 11 10 9 8 D2 1 R8 2 BAS16 82R C8 C41 470nF 470nF
16V 16V
board edge BC80 7-25 J33 Q1 220R C4 100pF r emove 2 pins to k eep isolat ion J34
C4 4 1uF
16V
D 20 R81 BAS16 82R
5 6 C5 470nF 25V +5V R9 0R C6 1nF 7
R7 82R R8
BC807 -25 J31 Q2 220R C7 100pF
remove 2 pins to k eep isolation
J32
VSS DAT A
J4 J14 J15 J13 J12 C 10 10nF
R 15 82R R1 6
BC8 07-25 J28 Q3 J29
IC2 L6386D LSIC2 1 2 HSIC2 3 4 5 R 26 6 7 C20 C17 2. 2nF 1nF 2.7K R 27 1K R1 8 1K +15V LIN VBOOT SD HIN VCC DIAG CIN GND HVG OUT NC NC LVG GND 14 13 12 11 10 9 8 D2 3 R84 BAS16 82R R 24 82R R83 D22 82R BAS16
J1 C11 10nF C 12 10nF C 13 10nF C 14 47pF +5V C 15
C43 10nF R17 10K
220R C9 100pF
remove 2 pins to k eep isolation
R 19 100K J11 J10 J9 J8 J7 J6 J5 J3 R3 8 100K R 39 100K C23 10nF C 24 10nF
R2 0 R2 1 100K 100K
R 22 R2 3 100K 100K
470nF 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 34 VDD VSS 33 P3.0 /MOSI T ACHO 32 P3.1 /MISO VH 31 P3.2 /WKUP3/SCK VL 30 P3.3 /SSN WH 29 P3.4 /EXTRG/OCMPB WL 28 PS3.5 /OCMPA/INT6 UH 27 P3.6 /ICAPA/WKU P2 UL NC NC 26 25 AVDD VPP_T EST 24 AVSS WKUP1/ICAPB/P5.0 23 P5.7 /AIN7/IN TCLK W KUP0/NMI/P5.1 22 P5.6 /AIN6/CK_AF RESETN 21 P5.5 /AIN5 OSCOUT 20 P5.4 /AIN4 OSCIN 19 VSS P5.3 /AIN3/WDOUT 18 P5.2 /AIN2/IN T0/WDIN VDD IC3 ST 92T 141K4M6 +5V
TP 2TP4 TP6 TP1 TP 3TP 5
BC807 -25 R2 5 Q4 220R C1 8 100pF J25 J27 J26
+5V R28 100K R 29 100K R3 0 100K R31 100K R32 100K R 33 100K R34 100K
H S IC 1 L S IC1 H S IC 2 L S IC2 H S IC 4 L S IC4
C16 +5V C1 9 R3 5 100K C21 470nF 10nF 470nF 25V
J18
C22 C 42 470nF 470nF
16V 16V
C2 5 10nF
C 26 10nF
C 27 10nF
C28 10nF
C29 10nF
R 36 82R R3 7 D2 4 R85 220R BAS16 82R C3 0 100pF
remove 2 pins to k eep isolation
BC807 -25 Q5
XT1 CST CC-MG 5MHz
XT_CSTCCMG_REV1
LSIC4
IC4 L6386D 1 2 LIN VBOOT SD HIN VCC DIAG CIN GND HVG OUT NC NC LVG 14 13 12 11 10 9 R8 6 D25 82R BAS16 R 46 82R
J23
R 40 100K
R4 1 R4 2 R43 100K 100K 100K
R4 4 100K
+5V R 45
220R
C31 10nF
C32 470nF T P7 +15V
HSIC4
J24
3 4 5
remove 2 pins to k eep isolation
BC80 7-25 R4 7 220R Q6
C 35 C3 3 100nF +5V R4 9 1M D3 BAS16 1 8 R63 390R R8 0 6. 8K R 50 100K R shun t
1%
6 7
J21
+5V
C3 4 470nF 25V
1nF R 48
C36 1nF
820R 1%
GND 8
C3 7 100pF
J22
R5 1 1% J20 4.7K
TP8
+3 -2
C 38 1uF
U1A LM3 58D 4
This drawingmay not be reproduced to a third party unless permiss ionis obtained in writing from ST MICRO ELECTRONICS
Title:
ST92141-ENG3
MCCC Rou sset
Document Number
Drawn by:
J-M RAVON
Or ganisation name:
Approved by: Rev 1
J2 Rq: All fo otpr int compon ents are 0603 package s except when noticed
Size

Date: Sheet W ednesday, November 21, 2001
1
of
1
This circuit can be used in various AC motor drive applications. This explains why there is some redundancy. The board can be populated in different ways depending on the application environment. For example: - The gate drive circuit can be simplified depending on power management and EMC optimization - The EEPROM memory is not needed if register data retention is not required - One interfacing IC can be omitted for single phase control
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DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACING BOARD...
6 ST92141-PLATFORM MECHANICAL DATA
CONTROL BOARD LAYOUT (Orcad files available)
TP6 TP5 TP4 TP3 TP2 TP1
C21
C32 XT1 R35 U1 R45 C38 R49 R50
1
R17
C15
ST92141-ENG3
C41 C42 Q7
R2 R12
TP8
R13 R11 R10 R34 R33 R32 R31 R30 R29 R28 R14
R6
R21
R22
R20
R19
R44
R43
R42
R41
R40
R39
R38
R82
R83
D21
D22
R84
D23
R85
D24
R4 C12 C13
C11 C10 C29 C28 C27 C26 C25
C24
R54
C23 C14
D1 C3
R23
C2 R1
D2
C31
R9
IC3
C33
D3
TP7 C44 D26 C46 U2 C39 C34 C43 R80 R51 R63 C19 C5 R48 C36 C35 C22 C17 R27 R26 C20 R18 C16
C6
I C4 R47 R36 C37 R37
IC2 R16 C18 R15
I C1
C8
C1
R56
R46 R86
ST92141-ENG3
R25 C30 R24
R7 C9
R8 C7
R3
R5 C4
D25
Q2
Q1
Q5
Q4
Q3
Q6
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DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACING BOARD...
7 CONNECTION DESCRIPTION
Name UHVG ULVG VHVG VLVG WHVG WLVG OUTU OUTV OUTW ULem VLem WLem Pgrd Isense Tsense V15 VDD Comp Rshunt Tacho1 Tacho2 P5.0 P3.0 P3.1 P3.2 P3.3 P3.4 P3.5 P3.6 P5.7 P5.6 P5.4 P5.3 AVDD Position J33 J31 J28 J26 J23 J21 J34 J29 J24 J32 J27 J22 J18 J25 J20 J19 J1 J30 J2 J16 J17 J4 J14 J15 J13 J12 J11 J10 J9 J8 J7 J6 J5 J3 Function Phase U high side gate drive Phase U low side gate drive Phase V high side gate drive Phase V low side gate drive Phase W high side gate drive Phase W low side gate drive Phase U high side emitter Phase V high side emitter Phase W high side emitter Phase U low side emitter Phase V low side emitter Phase W low side emitter Power Ground Instantaneous current sense input Thermal sensor input 15V supply voltage 5V supply voltage Comparator input Average current sense input Tacho meter input Tacho meter input Digital I/O or timer input Digital I/O or SPI Digital I/O or SPI Digital I/O or SPI Digital I/O or SPI Digital I/O or timer input Digital I/O or timer input Digital I/O or timer input Analog input or I/O Analog input or I/O Analog input or I/O Analog input or I/O A/D converter analog reference Comments
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DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACING BOARD...
8 TYPICAL APPLICATION: AC MOTOR DRIVE
The typical application for this Control Board is AC motor control. Figure 1 shows a power environment that fits this Control Board and runs an AC motor up to 600W from a 230Vac mains. The power range can be extended to 1kW by doubling the bulk capacitor and adapting the heatsink. An example implementation is shown in Figure 2. The Control Board is mounted on the Power Board next to the power switches. Figure 1. AC Motor Drive Schematic
Motor
H1
1 2 3 4 5
R 73 33K J1 7
Tacho Meter
J 16
EI48
H2
1
NTC 1
2
2
4
2XTP10
C 72 D 41 C 73 2.2uF 25V C 70 220uF 385V D 42 BZX55C 15 1 10uF 25V 3
FB
8 7 6 5
D4 0 TP 9 4+1
2
4.7R
L3
STTA106
D4 3
1N4 148 R 70 1M
Power
VDD
DRAIN
S ET
0.23V
+
IC6 V IPER12AD IP L2
+ 15V
TP 3
J 19 TP4 +5V
J7
R ES
STBR 408 2XTP2 3
C 75 22nF
S OURCE
1mH TS L1112 D 46 2 11 Vin
IC7 L78L05AC Z Vout GN D 2 J1 3 TP 14 C 71 B ZX85C5V 1 25V 100uF D 45 1 2 R7 1 12K
F1 5A Slow SU P FU SE 3527
1 2
TP11
R 79 1.5K
D 44 STTA1 06
D 47 GREE N LED
R7 4
BZX85C1 6
+ 5V
0.047R STGP7NB6 0H DFP J33 T1 2XTP5
R 76 10K 4 1
* R 75 4.7K
J2
* not mounted
J34
TP27
IC8 S FH61 7A R 77 3 2
S TGP7N B60HD FP J31 T2
I2C
H3
2XTP15
OV
1
4.7K J32 1 4
DAT
2
J1 4 IC 9 S FH61 7A STGP7NB6 0H DFP J 28 T3 2XTP17 2 3 TP26 R 78 4.7K TP23 1 4 J1 3 J2 9
CLK
3
-5 V
4
SFH 617A J 15 IC1 0 2 3 TP25 1 TP24 TP22 2 3 SW1 1K2 1 2 3 S W2 1K2 J2 0
t
J 26 + 5V J6 J3 J5 J 27 S1 1 2 J 25 AVD D U2 LM335Z P1 P2
STGP7NB6 0H DFP T4
2XTP7
STGP7N B60HD FP J 23 T5
R 72 0.047R 2W
C 74 47nF
400V
Tr immer 50K Tri mmer 50K J1 8 J 24
2XTP19
H5 1 2
J1 0
J8 A VDD
J11 J 21
STGP7NB6 0H DFP T6
J30
J 22
Water Level
Speed Reference
1 2 1 H6 H7
Position Sensor
2 J4
X1
X3
J12 Title :
WASHERPLATFORM-ENG2
MC CC Rousset
D raw n by:
J -M R AVON
Organi sation name: X2 X4 J9 S ize Th is draw ing may not be reproduced to a third party unles s permi ss io n is obtained in writin g from ST MICROELECTR ONIC S D ate:
Approve d by:< OrgAddr2> R ev S heet 1 of 1
Do cument Nu mber Wednesday, Nove mber 21, 2001
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DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACING BOARD...
Figure 2. Power Board Layout (ORCAD files available)
MOTOR 5 4 3 H1 H1 2 1 R73 R73 U2 U2 X1 T1 T1 2XTP15 T2 T2 T3 CC74 74 2XTP7 2XTP5 T3 T4 T4 T5 T5 T6 T6
R72 C70
C70
+
D45 D47 K D47 K R79 R79 D41 C73 C73 D41 C75 C75
D45 D46 IC7 + IC7 R70 R70 TP14 C71 C71 P2 P2 TP4 D46 R71 R71 P1 P1
+
IC8 IC8 R75 R75
C72
C72
L2 TP3
+
D42 D42
IC6 IC10 L3
IC10
IC9 SW1 +5V TP23
-
D40
+
NTC1 NTC1
WASHERPLATFORM-ENG2
1
MICROELECTRONICS
2XTP2
TP9
F1
F1
2XTP10
L3
TP25
R74
TP24
WASHERPLATFORM-ENG1
D40
+
1 2
H2 H2
TP22
TP26
MICROELECTRONICS
TP11
L2
D43 D43
IC9
TP27
IC6
2XTP19 H6 SR H5 WL H7 PS H6 H5 H7 R77 R77 R78 R78 R76 R76 H3 SW1 SW2 SW2 POWER H3 I2C
2XTP17 J30 J31 J32 J28 J29 J25 J26 J27 J23 J24 R74
R72 2
S1
J33 J34
J1 J2 J3 J4 J5 J6 J7 J8 J9 J10 J11 J12 J13 J14 J15 J16 J17 J18 J19 J20 J21 J22
D44 D44
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DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACING BOARD...
9 SYSTEM VIEWS
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DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACING BOARD...
10 WASHER MOTOR DRIVE DEMONSTRATION SOFTWARE
A large number of generic macros are available to allow you to build software for your specific application (refer to AN1084, AN1277 and AN1367). To show how quickly it can be implemented, a washer motor drive demonstration program is presented in this application note. This sofware allows you to evaluate the performance of the ST92141 based Control Board coupled to six STGP7NB60HDFP IGBTs and controlling a 3-phase induction motor in a washing machine application. For the hardware description, refer to the schematics shown previously. This demonstration software has been developed with ST92141 Software Library release 2.1. The application is made up of the following five modules, in addition to the Software Library modules: - User - Supervision - Watchdog - EFT (timer) - Unbalancement
Disclaimer:
THE PRESENT SOFTWARE, WHICH IS FOR GUIDANCE ONLY, AIMS AT PROVIDING CUSTOMERS WITH INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME. AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE CONTENT OF SUCH SOFTWARE AND/OR THE USE MADE BY CUSTOMERS OF THE INFORMATION CONTAINED HEREIN IN CONNEXION WITH THEIR PRODUCTS. 10.1 ST92141 SOFTWARE LIBRARY This library provides ready-to-use functions to run a standard three-phase AC motor. It is fully documented in application notes AN1084, AN1277 and AN1367. The motor parameters (max. voltage, optimum slip, number of poles, tachometer characteristics...) can be set easily to fit the motor characteristics. The default parameters correspond to the AHV SELNI motor. 10.2 ST92141 DEVELOPMENT TOOLS ST9+ V6 Software Toolchain. See http://www.st.com, Microcontroller section.
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DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACING BOARD...
10.3 HOW TO RUN THE SOFTWARE The SW1 and SW2 switches allow the 3 following modes to be selected: - Wash mode 1 - Wash mode 2 - Spinning mode (see schematics for pin-out) 10.3.1 Wash mode 1 Rotor speed is 90Hz (WASH SPEED constant in USERParm.h) Ton = 3sec., Toff = 12sec. The direction is toggled after each cycle.
Speed (RPM)
Wash speed
Toff
Ton
Time (s)
10.3.2 Wash mode 2 Rotor speed is 90Hz (WASH SPEED constant in USERParm.h). Ton & Toff are adjusted by the RV2 & RV3 trimmers on the Power Board, 2sec. < Toff < 10sec., 5sec < Ton < 20sec. (turn clockwise to decrease time) Two trimmers can adjust the moving and waiting periods. The direction is toggled after each cycle.
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DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACING BOARD...
10.3.3 Spinning mode The spinning profile is defined in the table below (motor speeds in RPM and times in seconds): - If the time is equal to zero, then acceleration is as fast as possible (limited by maximum allowed torque) - If both speed and time are equal to zero, then the spinning phase ends and CPU waits for a new mode. The default profile is the following:
Rotor target speed (RPM) 1000 1000 0 1300 1300 3000 10000 10000 12000 12000 16000 16000 0 Time (s) 10 10 10 5 5 5 50 30 20 30 40 60 0
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DESIGNING A THREE PHASE AC INVERTER CONTROL & INTERFACING BOARD...
10.4 FUNCTIONAL DESCRIPTION 10.4.1 Soft Start This purpose of this function is to start the motor (in washing or spinning mode). The start-up consists of fixing the stator frequency and slowly increasing the motor voltage. The slip regulation is disabled. The voltage ramp has two slopes. The first slope is steeper than the second one. When the start-up speed is reached, the slip regulation is enabled and the CPU goes into sustaining speed mode (washing) or to ramping-up. Figure 3. Start-up
Starting up Max voltage allowed Sustaining speed
Voltage Speed threshold to be reached before exiting start-up mode Speed
Start-up timeout
Time
If the speed feedback is not available (for example due to a tachometer problem), a time-out stops the PWM and exits the start-up sequence. Figure 4. Start-up timeout
Start-up Max voltage allowed Voltage
Speed threshold to be reached before exiting start-up mode
Start-up timeout
Time
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Start-up optimization during wash cycles Figure 5. Repetitive start-up in wash cycles
Start-up
Sustaining speed
Average
Voltage
V0
Speed
T0
Time
T0 time is a constant. V0 voltage is the average applied during the final seconds before the last stop. This adaptive start-up allows torque to be optimized depending on the load (compromise between rise time and current over-shoot). The higher the load, the higher the torque needed to start the motor. 10.4.2 Ramp-up The ramp-up function allows the motor speed to be increased. It is defined by: - Target speed - Time needed to reach this target speed The stator frequency unit is 0.1Hz and the time unit is 10ms (regulation loop time). The difference between the target speed and the actual speed defines the number of steps (0.1Hz each). The time to reach the target speed versus the number of steps gives the step time. Therefore, the maximum slope is 10Hz per second. If the motor slip exceeds its allowed limit during the acceleration, the frequency does not increment until the slip comes within this limit. 10.4.3 Sustain speed The purpose of this function is to maintain the motor speed by regulating the optimal motor slip.
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10.4.4 Decrease speed In some cases, for example when the input power gets too high, the speed must be slowed down. This function saves the motor voltage and disables the slip regulation and the PWM. Then the motor speed decreases naturally. When it reaches the target speed, the new stator frequency is set and the PWM outputs are enabled. Simultaneously the motor voltage is increased progressively from zero to the previously saved value. The slip regulation routine may be started as well as the sustain speed routine. 10.4.5 Motor stop Before setting a new mode (washing, dry-spinning), the motor must be stopped to avoid energy return from motor to converter. 10.4.6 Voltage limitation See AN1084 10.4.7 Slip regulation See AN1084 10.4.8 Speed measurement protection / locked rotor During the start-up routine, if the timer overflows before the motor runs, either the rotor is locked or the speed is not accessible. After several trials, the default flag may be set. In normal operation, if the tachometer counter suddenly overflows, the PWM is immediately disabled. After checking, if problem re-occurs, the default flag may be set. 10.4.9 Unbalancement measurement Note: This is only an unbalancement measurement. Unbalancement control has to be implemented by the washing machine manufacturer. Unbalancement measurement is done at a fixed speed. It is based on the fact that the motor slip variation is proportional to that unbalancement. The algorithm is the following. First the average motor voltage is computed over a three second period. Then the slip regulation is disabled and the motor voltage is set to this average value. Then during one second, the motor slip span is measured. This span is averaged with four or five values, depending on the speed. The unbalancement is proportional to the average slip span. 10.4.10 Heatsink over-temperature A hardware protection (LM335 temperature sensor on the power board) disables the L6386 drivers and stops the motor in case of heatsink over-temperature. Therefore, the microcontroller software is interrupted by a falling-edge on the NMI interrupt pin. The PWM outputs are put in high-impedance.
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In wash mode, the motor is stopped and restarts as soon as the default disappears (high level signal on the NMI pin). In spinning mode, the motor is stopped and restarts at the beginning of the whole profile as soon as the default disappears. The over-temperature protection level can be adjusted by the R51/R48/R80 resistant divider and the R51/C36 filter on the Control Board. The default threshold is about 100C. 10.4.11 Thermal monitoring The microcontroller can also read the heatsink temperature through an analog input (not implemented in this software). The designer can program, for example, the following de-rated modes if temperature exceeds 90C: - Ton is shorted if washing - Spinning speed is decreased if spinning 10.4.12 DC bus voltage supervision If the DC line voltage decreases to 200V, the microcontroller stops the PWM to slow down the bulk capacitor discharge. Therefore the auxiliary supply can operate for a significant time preventing the microcontroller from resetting. The PWM is enabled as soon as the voltage reaches 200V. When washing, the CPU waits for the rotor stop and then restarts as soon as the default disappears (high level signal on the NMI pin). When spinning, the CPU waits for the rotor stop and then restarts the whole profile as soon as the default disappears. 10.4.13 Input power supervision In spinning mode, an input power limitation can be implemented, for two main reasons: - Limit the current harmonics emitted on the mains - Risk of heatsink over-heating The DC bus voltage and the peak input current values are measured via analog inputs. The product of these two values gives an indication of the input power. The default maximum power is set at about 600W (in USERParm.h). If the input power becomes higher than 600W, the speed is either decreased or limited depending on the operation (steady state or accelerating).
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10.4.14 Motor over-current A hardware protection disables the L6386 drivers and stops the motor in case of instantaneous over-current. In this case, the microcontroller software is interrupted by a falling edge on the NMI interrupt pin. The PWM outputs are put in high-impedance. In wash mode, the motor is stopped and restarts as soon as the default disappears (high level signal on the NMI pin). In spinning mode, the motor is stopped and restarts at the beginning of the whole profile as soon as the default disappears. The over-current protection threshold can be adjusted by the R26/R27 resistor divider and the R27/C17 filter on the control board. The default threshold corresponds to about 12A peak on the motor phase sinusoidal current. 10.4.15 Watchdogs (main watchdog and peripheral watchdogs) The Watchdog peripheral resets the microcontroller if the software locks-up. The PWM, A/D converter and EFT timer interrupts are managed by the software. These interrupts occur at regular intervals. The period of these interrupts is lower than the main loop time. A counter is incremented each time a PWM interrupt occurs. This counter value is read in the software main loop. If it is not equal to zero, it is reset and the main loop is kept running. If the counter is zero, an infinite loop is forced and the watchdog peripheral resets the microcontroller. Similar counters are set for the A/D converter and EFT timer.
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10.5 FUNCTION LIST
USER module
USER_Mode_Init USER_Mode_Detect USER_Calculate_VF_Wash_1 USER_Calculate_VF_Wash_2 USER_Wash USER_WashAverageVoltageInit USER_WashAverageVoltageUpdate USER_WashAverageVoltageCalculation USER_WashSoftStartVoltageDetermination USER_Init_Spinning_Array USER_Calculate_VF_Spin USER_SoftStart USER_InitRegul USER_SustainSpeed USER_RampUp USER_DecreaseSpeed
Supervision module (supervis.c)
USER_MicroCuts_Handling USER_NMI_Init NMI_Interrupt_Routine USER_NMI_Handling USER_TachoFailure_Handling USER_MainsPower_Handling Watchdog module Watchdog_Init Watchdog_Get_Counter_HB Watchdog_Reload USER_Reset_Watchdog_Counters USER_Watchdog_Handling EFT module EFT_Init EFT_OC1_Get_WDT_Counter EFT_OC1_Set_WDT_Counter EFT_OC1_Clear_WDT_Counter USER_TimebaseInit USER_Timebase USER_Sec_Counter_Elapsed USER_Sec_Counter_2_Elapsed; USER_Sec_Counter_3_Elapsed
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USER_Get_Sec_Counter_Value USER_Get_Sec_Counter_2_Value USER_Load_Sec_Counter USER_Load_Sec_Counter_2 USER_Load_Sec_Counter_3 USER_Read_Interface EFT_Interrupt_Routine Unbalancement module (unbal.c) USER_Unbal USER_UnbalRegul USER_UnbalAverageVoltageCalculation USER_UnbalStopRegul USER_UnbalSlipMeasurement USER_GetUnbal
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"THE PRESENT NOTE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS WITH INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME. AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE CONTENT OF SUCH A NOTE AND/OR THE USE MADE BY CUSTOMERS OF THE INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS."
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