AN967

AN967
Bidirectional VF Control of Single and 3-Phase Induction
Motors Using the PIC16F72
Author:
Padmaraja Yedamale
Microchip Technology Inc.
INTRODUCTION
Single-phase induction motors are extensively used in
appliances and industrial controls. The Permanent Split
Capacitor (PSC) single-phase induction motor is the
simplest and most widely used motor of this type. The
classification, construction and working principle of
single-phase induction motors are explained in detail in
the
application
note
“AC
Induction
Motor
Fundamentals” (AN887) available from Microchip. For
VF theory and basic operations, refer to AN887
mentioned above, and “Speed Control of 3-Phase
Induction Motor Using PIC18 Microcontrollers”
(AN843).
By design, PSC motors are unidirectional, which
means they are designed to rotate in one direction. By
adding either extra windings, and external relays and
switches, or by using gear mechanisms, the direction of
rotation can be changed. In this application note we will
discuss in detail, how to control the speed of a PSC
motor in both directions using a PIC16F72
microcontroller and power electronics.
The PIC16F72 microcontroller was chosen because it
is one of the simplest and low-cost general purpose
microcontrollers Microchip has in its portfolio. Even
though it does not have the PWMs in hardware to drive
complementary PWM outputs with dead band inserted,
all PWMs are generated in firmware using timers and
output to general purpose output pins.
The motor is energized with a single-phase AC power
supply, with a capacitor connected in series with the
start winding (also called an auxiliary winding) as
shown in Figure 1. The value of the capacitor is chosen
so that the total impedance on the auxiliary winding
produces sufficient phase shift in current to generate a
rotating magnetic field in the air gap.
Typically, the current flowing through the start winding
leads the current flowing through the main winding by
90 degrees.
By adding a microcontroller-based control circuit to the
motor, the voltage across the main winding and start
winding can be maintained at 90 degrees to each other.
The other advantage is that the starting capacitor can
be removed from the circuit, thus reducing the total
system cost.
FIGURE 1:
ELECTRICAL EQUIVELANT
CIRCUIT OF A PSC MOTOR
VMAIN
L
AC
Main
Winding
Squirrel
Cage Rotor
N
Starting
Winding
VSTART
A multiphase inverter can be used to drive the motor.
Two methods are discussed in the next section.
THEORY OF OPERATION
A PSC motor is usually a 2-phase asymmetrically
wound motor. The main winding is designed to take the
load current. The current flowing through the start
winding is much less than the main winding. Therefore,
the start winding will have a different electrical
characteristic compared to the main winding. In order
to produce the Magnetomotive Force (MMF) produced
by the start winding very near to the main winding, the
start winding has additional turns, higher resistance,
and reduced current flowing through it. This makes the
motor windings asymmetrical.
© 2005 Microchip Technology Inc.
DS00967A-page 1
AN967
DRIVE TOPOLOGY
The control circuit requires four PWMs with two
complementary pairs with sufficient dead band
between the complementary outputs. PWM0-PWM1
and PWM2-PWM3 are the PWM pairs with dead band.
The PIC16F72 does not have PWMs designed in the
hardware to output the way we need. Therefore, the
PWMs should be generated in firmware and output to
the port pins. Using PWMs, the DC bus is synthesized
to give two sine voltages at 90 degrees out of phase
with varying amplitude and varying frequency
according to the VF profile. If the voltage applied to the
main winding lags the start winding by 90 degrees, the
motor runs in one (i.e., forward) direction. To reverse
the direction of rotation, the voltage supplied to the
main winding should lead the voltage supplied to the
start winding.
Using an H-Bridge Inverter
The first approach is relatively easy as far as the
power circuit and control circuit are concerned. On
the input side, a voltage doubler is used and on the
output side an H-bridge, or 2-phase inverter, is used
as shown in Figure 2. One end of the main and start
windings are connected to each half bridge and the
other ends are connected together to the neutral
point of the AC power supply, which also serves as
the center point for the voltage doubler.
Figure 3 and Figure 4 show the main and start winding
voltages in forward and reverse respectively.
FIGURE 2:
PSC DRIVE WITH AN H-BRIDGE
PWM1
L
PWM3
PWM3
Vm
N
PWM2
Gate Driver
AC
PIC16F72
PWM1
VMAIN
VSTART
Vm +
- π /2
Start
Winding
PWM0
PWM0
DS00967A-page 2
Main
Winding
PWM2
© 2005 Microchip Technology Inc.
AN967
FIGURE 3:
MOTOR RUNNING IN FORWARD DIRECTION
150.00
VMAIN = Sin(ωt)
% Phase Voltage
100.00
50.00
VMAIN
0.00
0
50
100
150
200
250
300
350
400
VSTART
-50.00
-100.00
VSTART = Sin(ωt+π/2)
-150.00
Phase Angle
FIGURE 4:
MOTOR RUNNING IN REVERSE DIRECTION
150.00
VMAIN = Sin(ωt)
% Phase Voltage
100.00
50.00
VMAIN
0.00
0
50
100
150
200
250
300
350
400
VSTART
-50.00
-100.00
VSTART = Sin(ωt-π/2)
-150.00
Phase Angle
© 2005 Microchip Technology Inc.
DS00967A-page 3
AN967
This method of controlling a PSC type motor has a
few disadvantages.
• Because the main winding and start windings
have different electric characteristics, the current
flowing through each switch is unbalanced. Over
time, this may lead to premature breakdown of
switching devices in the inverter.
• The common point of the windings is directly
connected to the neutral power supply. This may
increase the switching signal coming into the
mains power supply and increase the noise emitted onto the line. This also may limit the EMI level
of the product, violating certain design goals and
regulations.
• The effective DC voltage handled is high due to
the input voltage doubler circuit.
• Lastly, the cost of the voltage doubler circuit itself
is high because of two large power capacitors.
With this drive topology, control becomes more efficient; however, the control algorithm becomes more
complex. The voltages Va, Vb and Vc should be controlled to achieve the phase difference between the
effective voltages across the main and start windings to
have a 90 degree phase shift to each other.
The turn ratio of the start winding to the main winding is
defined by:
EQUATION 1:
V MAIN
α = --------------------V START
where α is the turn ratio, and VMAIN and VSTART are the
effective voltage across the main winding and the start
winding.
A better solution to minimize these problems would be
to use a 3-phase inverter bridge, as discussed in the
next section.
In order to have equal voltage stress on all devices,
thus improving the device utilization and provide the
maximum possible output voltage for a given DC bus
voltage, all three inverter phase voltages are kept at the
same amplitude as follows:
Using a 3-Phase Inverter Bridge
EQUATION 2:
The input section is replaced with a standard diode
bridge rectifier. The output section has a 3-phase
inverter bridge. The main difference from the previous
scheme is the way the motor windings are connected
to the inverter. One end of the main winding and start
windings are connected to one half bridge each. The
other ends are tied together and connected to the third
half bridge, as shown in Figure 5.
Refer to Appendix B: “Schematics” for the schematics that reference the PIC16F72 with a 3-phase inverter
bridge.
FIGURE 5:
| Va | = | Vb | = | Vc | = | V1 |
The effective voltage across the main and start winding
is given as:
EQUATION 3:
VMAIN = Va – Vc
VSTART = Vb – Vc
The voltages are shown in the phasor diagram in
Figure 6.
CONTROLLING A PSC MOTOR WITH A 3-PHASE INVERTER BRIDGE
PWM1
PWM3
PWM5
PWM5
PWM3
PWM4
PWM2
Gate Driver
AC
PIC16F72
PWM1
Main
Winding
Va
Vb
Vc
Start
Winding
PWM0
PWM0
DS00967A-page 4
PWM2
PWM4
© 2005 Microchip Technology Inc.
AN967
FIGURE 6:
VOLTAGE PHASOR
DIAGRAM
Because the turn ratio remains constant for a given
motor, α can be a compile time option. With this, θ and
V1 can be precomputed for a given motor. This simplifies the run time calculation. Based on the phase angle,
phase voltages Va, Vb and Vc can be calculated as:
~
Vc
~
~
~
VSTART = Vb – Vc
V1
αV
ζ
EQUATION 6:
V
V dc
V a = V1 × cos ( ωt ) + --------2
θ
V1
~
Vb
~
~
~
VMAIN = Va – Vc
V1
V dc
V b = – V1 × cos ( ωt ) + --------2
~
Va
V dc
V c = V1 × cos ( ωt ± θ ) + --------2
As seen in the phasor diagram in Figure 6, the voltages
across phase A and phase B are out of phase, and the
phase difference between phase A and phase C is θ
degrees. By applying basic trigonometry, θ can be
calculated by:
Vdc is the DC bus voltage, and ωt is the angular velocity
of the electrical cycle. The direction of rotation can be
easily controlled by adding or subtracting θ in the Vc
calculation.
EQUATION 4:
Angle θ = 180° – 2 tan-1 (α).
Figure 7 shows the phase voltages Va, Vb and Vc, and
Figure 8 shows the effective voltages across the main
winding (VMAIN) and the start winding (VSTART).
By applying the Pythagorean Theorem, the voltage
vector V1 can be calculated as:
Figure 8 also shows that the effective phase difference
between the voltages is 90 degrees and the effective
voltage ratio is α.
EQUATION 5:
( 1 + α2 )
V1 = V × -----------------------2
FIGURE 7:
PHASE VOLTAGES Va, Vb and Vd
100
80
60
% Phase voltage
40
20
Va
Vb
0
0
50
100
150
200
250
300
350
400
Vc
-20
-40
-60
-80
-100
Phase angle
© 2005 Microchip Technology Inc.
DS00967A-page 5
AN967
FIGURE 8:
VOLTAGE ACROSS MAIN WINDING (VMAIN) AND START WINDING (VSTART)
150
% Phase Voltage
100
50
VMAIN
0
0
50
100
150
200
250
300
350
400
VSTART
-50
-100
-150
Phase Angle
DS00967A-page 6
© 2005 Microchip Technology Inc.
AN967
IMPLEMENTATION USING THE PIC16F72
After five instruction cycles, the complementary PWM
is turned ON. This gives a dead time of 1 μs when the
microcontroller is running at 20 MHz. When the count
reaches 624, all outputs are turned OFF. A new PWM
cycle starts after 10 instruction cycles.
In order to control a 3-phase inverter bridge, we need
three PWM pairs with complementary outputs. In addition, each complementary pair of PWMs needs dead
time in between any OFF and ON switch events to
avoid a DC bus short circuit. The PIC16F72 does not
have these features in the hardware. However, this can
be easily implemented using a general purpose timer
and six output pins as shown in Figure 9.
In the source code provided with this application note
(see Appendix A: “Source Code”), instead of comparing the Timer1 values corresponding to the duty
cycle values, a relative count is calculated with respect
to the previous PWM duty cycle. This count is subtracted from 0xFF (Timer1 is configured as an 8-bit
timer) and loaded to the Timer1 register. When the
Timer1 value overflows, in Timer1 overflow ISR, the
corresponding Odd PWM is turned OFF and the corresponding Even PWM is turned ON after five instruction
cycles. This is done for all three pairs of PWM. Refer to
the flowcharts in Figure 10 through Figure 11 for more
details.
Generating Software PWMs
The scheme shown here gives a fixed PWM frequency
of approximately 7.9 kHz. Timer1 (1:4 prescale) is
counted up from 00 to 634. At the beginning of the cycle
(when Timer1 = 00), the PWMs controlling the upper
switches (i.e., PWM1, PWM3 and PWM5) are turned
ON. Based on the individual PWM duty cycle, the
corresponding PWM output is turned OFF.
FIGURE 9:
PWM SOFTWARE IMPLEMENTATION
624
634
Timer 1 counting UP
from 00 to 634
00
PWM period = 634 for ~8 kHz PWM frequency @ 20 MHz FOSC
PWM 1/3/5
ON
PWM 3
OFF
PWM 1
OFF
PWM 0
ON
Dead Time
Note:
PWM 5
OFF
PWM 2
ON
Dead Time
PWM 1/3/5
ON
PWM 4
ON
Dead Time
PWM 0/2/4
OFF
Dead Time
The PWMs are numbered with respect to Figure 5.
© 2005 Microchip Technology Inc.
DS00967A-page 7
AN967
FIGURE 10:
MAIN LOOP
MAIN_LOOP
Start
No
Is S1
pressed?
Yes
Initialize
PORTB – Fault and toggle switch interface
PORTC – PWMs
Copy Sine table values to
RAM locations
Initialize ADC to read Motor current
and Potentiometer
Initialize Timer0, Timer1, Interrupts
and Sine table offsets
No
Timer0
rollover?
Yes
Update PWM duty cycles (A)
(UPDATE_PWM_DUTYCYCLES)
Prioritize PWM duty cycles (B)
(PRIORITIZE_PWMS)
Calculate new speed
Set ADC ‘GO’ bit
Is ADC
Yes
result ready?
C
AD_CONV_COMPLETE
No
DS00967A-page 8
© 2005 Microchip Technology Inc.
AN967
FIGURE 10:
MAIN LOOP (CONTINUED)
PRIORITIZE_PWMS
UPDATE_PWM_DUTYCYCLES
B
A
Read value pointed by TABLE_OFFSET1 from
the Sine table (corresponds to PWM1/0 pair)
No
PWM1/0 duty cycle =
Sine (TABLE_OFFFSET1) x NEW_FREQ
Is PWM3<
PWM1?
Yes
Interchange PWM1 and PWM3 duty cycles
Read value pointed by TABLE_OFFSET2 from
the Sine table (corresponds to PWM3/2 pair)
PWM3/2 duty cycle =
Sine (TABLE_OFFFSET2) x NEW_FREQ
No
Read value pointed by TABLE_OFFSET3 from
the Sine table (corresponds to PWM5/4 pair)
Is PWM5<
PWM3?
Yes
Interchange PWM3 and PWM5 duty cycles
PWM5/4 duty cycle =
Sine (TABLE_OFFSET3) x NEW_FREQ
No
Return
Is PWM3<
PWM1?
Yes
Interchange PWM1 and PWM3 duty cycles
Return
AD_CONV_COMPLETE
C
NEW_FREQ = ADRES
MOTOR_CURRENT = ADRES
HEATSINK_TEMP = ADRES
Set limit on NEW_FREQ
0x30 < NEW_FREQ < 0xD0
No
Motor current >
MAX_MOTOR_CURRENT?
No
HS Temp>
MAX_HEATSINK_TEMP?
Set ADC mux to read motor current
(for next cycle)
Yes
Set OVER_CURRENT
flag
Set OVER_TEMPERATURE flag
Return
© 2005 Microchip Technology Inc.
DS00967A-page 9
AN967
FIGURE 11:
INTERRUPT SERVICE ROUTINES (ISR)
ISR_INT
CHECK_FAULT
Context Save: WREG and STATUS
Yes
Timer1 ISR?
INT
OVER_CURRENT_COUNT (OC_COUNT) =
OVER_CURRENT_COUNT - 1
T1
TIMER1_OVERFLOW
No
No
Is OC_COUNT = 0?
Yes
Timer0 ISR?
T0
Yes
TIMER0_OVERFLOW
STOP_MOTOR
No
x
Yes
INT ISR?
INT
CHECK_FAULT
TIMER0_OVERFLOW
No
Restore: WREG and STATUS
T0
x
Timer0 = Count for NEW_FREQ
RETFIE
Reset overcurrent filter count
x
TIMER1_OVERFLOW
T1
Lowest PWM Duty Cycle
Turn Off Odd Channel w/least
PWM Duty Cycle value
5 Cycles Delay
(Dead Time = 1 μS)
Highest PWM Duty Cycle
Medium PWM Duty Cycle
New PWM Duty Cycle
Turn Off Odd Channel w/medium
PWM Duty Cycle value
Turn Off Odd Channel w/highest
PWM Duty Cycle value
Turn Off All 6 Channels
5 Cycles Delay
(Dead Time = 1 μS)
5 Cycles Delay
(Dead Time = 1 μS)
5 Cycles Delay
(Dead Time = 1 μS)
Turn ON All Odd PWM
Channels (1, 3 and 5)
Turn ON Complementary
Channel
Turn ON Complementary
Channel
Turn ON Complementary
Channel
Timer1 = Medium Duty Cycle –
Lowest Duty Cycle
Timer1 = Highest Duty Cycle –
Medium Duty Cycle
Timer1 = End of PWM Cycle –
Highest Duty Cycle
Timer1 = Lowest Duty Cycle
x
DS00967A-page 10
© 2005 Microchip Technology Inc.
AN967
Initialization
• PORTC<0:5> are initialized to output PWMs.
• Timer1 is initialized with 8-bit operation and 1:4
prescale.
• A/D channels are initialized to read frequency
reference (AN0), motor current (AN1) and
heatsink temperature (AN2).
- Frequency reference is read using a
potentiometer connected to A/D Channel 0.
- Motor current is read using a shunt resistor in
the DC return path. The voltage
corresponding to the motor current is
amplified and connected to A/D channel 1.
• Timer0 is used for setting the motor frequency
based on the potentiometer setting. On every
Timer0 overflow, new PWM duty cycles are
advanced by 10 electrical degrees on the Sine
table.
• The Sine table is loaded into RAM
• Timer0 overflow, Timer1 overflow and INT
interrupts are enabled.
Main Routine
These tasks are done in the MAIN_LOOP routine:
• New PWM duty cycle is calculated by the
subroutine UPDATE_PWM_DUTYCYCLES
Three pointers pointing to three different values on
the Sine table corresponding to the phase
difference between Va, Vb and Vc. The sine table is
drawn to maximum duty cycle available when the
sine value reaches 90 degrees. Every value is
scaled down based on the frequency input to
follow a linear VF profile.
• PWM duty cycle sorting is handled by the
subroutine PRIORITIZE_PWMS
PWM duty cycles calculated earlier are sorted in
ascending order, so that the duty cycle with minimum ON time can be addressed first and PWM
with maximum duty cycle last. Corresponding
Flags are set to indicate which PWM duty cycle
corresponds to which PWM output.
© 2005 Microchip Technology Inc.
• Timer0 reload value is calculated by the
subroutine TIMER0_OVERFLOW
Timer0 is used for setting the motor frequency. The
Timer0 reload value is calculated based on three
factors: first is the frequency reference input from
the potentiometer, second is the number of sine
table values, and third is the MCU operating
frequency.
• Polling for the ADC result is handled by the
subroutine AD_CONV_COMPLETE
ADC conversion is poled in the main routine.
Alternatively, frequency reference (AN0), motor
current (AN1) and heatsink temperature (AN2) are
selected and converted.
Interrupt Service Routines (ISRs)
• Timer1 ISR: In the first three Timer1 overflow
ISRs, the corresponding Odd PWM output is
turned off in each ISR. The complementary output
is turned on after a dead time of five cycles (1 μs).
In the fourth Timer1 overflow ISR, the PWM cycle
is restarted. All PWMs are turned OFF and the
timer is loaded with the value corresponding to
the lowest duty cycle value. This is repeated for
each PWM cycle.
• Timer0 ISR: A flag is set to indicate that the Sine
output should advance by 10 degrees on the Sine
table. The Timer0 registers are reloaded with the
value corresponding to the motor frequency
reference.
• INT ISR: The INT pin is used to interface hardware overcurrent fault. Motor current is compared
with a fixed voltage reference using an op amp
comparator. Each time the motor current exceeds
the reference, in INT ISR a count (0C_COUNT) is
decremented. If the count reaches zero in one
Timer0 cycle, then the motor is stopped and
overcurrent is indicated. This count is reset in
every Timer0 ISR.
DS00967A-page 11
AN967
Controlling a 3-Phase Induction Motor
The DC bus is modulated with these PWMs to give
three Sine voltage outputs with 120 degrees phase
shift to each other as shown in Figure 12. This can be
done by changing the offset pointers on the Sine table.
Firmware needs to be recompiled and the part should
be reprogrammed. To reverse the motor direction, the
PWM loaded to two of the phases should be
interchanged.
The advantage of the drive topology shown in Figure 5
is the same hardware can be used to control the
speed of a 3-phase induction motor. In order to control
a 3-phase induction motor with a Variable Frequency
(VF) technique, three pairs of complementary PWMs
with dead band are required.
FIGURE 12:
PHASE VOLTAGE FOR 3-PHASE INDUCTION MOTOR CONTROL
150
Sin(ωt)
Sin(ωt+120)
Sin(ωt+240)
% Phase Voltage
100
50
Sin(wt)
0
Sin(wt+120)
0
50
100
150
200
250
300
350
400
Sin(wt+240)
-50
-100
-150
Phase Angle
PIC16F72 LIMITATIONS
CONTROL USING A PIC18F2431/4431
Using the PIC16F72 for control has the following
limitations:
The PIC18FXX31 MCUs have a state-of-the-art Power
Control PWM (PCPWM) module on-chip. This module
can provide three pairs of complementary PWMs with
programmable dead band. Programming is greatly
simplified using PIC18FXX31 devices, because it
reduces the task of generating the software PWMs,
which takes most of the processor resource on a
PIC16F72. The source code included with this
application note (see Appendix A: “Source Code”)
also includes single-phase VF control using the
PIC18F2431.
• MIPS: Generating a software PWM takes
significant processing power. This limits any other
application that may be required to run on the
same MCU.
• PWM Frequency Range: The PWM frequency
range is limited and requires firmware changes.
The safe PWM frequency range is from 6 kHz to
10 kHz with an operating frequency of 20 MHz.
The PWM cycle may have an error up to ±5%.
The resolution is also limited between 6 to 8 bits.
In addition to this, generating PWM outputs in
firmware uses the on-chip Timer, program and
data memory.
DS00967A-page 12
To
learn
more
about
using
PIC18FXX31
microcontrollers for different types of motor controls,
refer to application notes AN899, Brushless DC Motor
Control
Using
PIC18FXX31
Microcontrollers
(DS00899) and AN900, Controlling 3-Phase AC
Induction Motors Using the PIC18F4431 (DS00900)
available from Microchip.
© 2005 Microchip Technology Inc.
AN967
CONCLUSION
APPENDIX A:
Microcontroller-based control for a PSC motor makes
the system easy to implement and have control over
the motor in two directions. Implementing the
algorithm using a 3-phase inverter bridge gives
flexibility and efficiency of control. In addition, a 3phase induction motor can be controlled using the
same hardware by making minor modifications to the
firmware. The PIC16F72 is a popular low cost general
purpose microcontroller from Microchip, that can be
used to implement the control algorithm. To a great
extent, PIC18FXX31 devices can provide flexibility in
implementing motor control algorithms.
The complete source code is available for download as
a single archive file from the Microchip corporate web
site at:
© 2005 Microchip Technology Inc.
SOURCE CODE
www.microchip.com
DS00967A-page 13
DC-
R6
C11
+
R9
15K
0.0
R10
2
3
1
2
3
4
100
R11
IR2153-DIP8
8
7
6
5
1EMU06
D2
VB
HO
VS
LO
1N4148
VCC
RT
CT
COM
220 pF
C3
22 pF
10K
D1
U3
FREF
CCW
CW
2
+5V
R1
0.1 μF
C2
1
S1
4
+5V
C12
R5
2K
470K, 0.5W
4.7 μF, 25V
0.1 μF
C10
Power
Supply
DC+
PIC Interface
®
3
1
DS00967A-page 14
Y1
22
R7
20 MHz
2K
R3
1
IRFR420A
C6
0.1 μF
C4
22 pF
FREF
MOTOR
TEMP
C1
0.1 μF
RA3
RA4
RA5
RA0
RA1
RA2
RC0
RC1
RC2
RC3
RC4
RC5
RC6
RC7
RB0
RB1
RB2
RB3
RB4
RB5
RB6
RB7
L1
11
12
13
14
15
16
17
18
21
22
23
24
25
26
27
28
TL431-T092
D4
2
3
1
R12
2K7
+
C7
1
R4
4
3
IN
3
S2
+
C8
1
2
C9
0.1 μF
+5V
10K
R2
+5V
10 μF, 25V
OUT
U2
LM340T -5.0V
0.1 μF
C5
10K
SW1
100 μF, 25V
+15V
PWM0
PWM1
PWM2
PWM3
PWM4
PWM5
FAULTA
SW1
560 μH, 0.5A
R8
11K
PIC16F72
D3
1EMU06
Q1
8 VSS
19 VSS
10 OSC2
9 OSC1
2
3
4
5
6
7
1 MCLR
20 VDD
2
FIGURE B-1:
3
APPENDIX B:
2 COM
+5V
AN967
SCHEMATICS
PIC® INTERFACE AND POWER SUPPLY (SHEET 1 OF 2)
© 2005 Microchip Technology Inc.
© 2005 Microchip Technology Inc.
4
3
2
1
Motor
Connector
J2
EARTH
M3
M2
M1
R22
AUX
TEMP
PSC
MOTOR
MAIN
300
R20
0.05R/3W
DC-
C18
33 pF
4.7 nF
C19
1K
R16
1
C21
RV1
EARTH
J1
91K
2
+
1
U5:A
C14
0.1 μF
3
R24
NTC
F1
1K
R15
AC INPUT
MCP6002
0.01 μF 270 VAC
R18
10K
R19
3
2-
+5V
8
4
4 AC2
1
AC1
D5
DC-
3
+
-
C17
33 pF
IMOTOR
2
R13
2K4
R21
5K
5 +
6 -
+ C20
470 μF 250V
DC+
+5V
R17
MCP5002
1M
U5:B
7
R14
300
FAULTA
FIGURE B-2:
IRAMS10UP60A
C13 10 μF 16V
VB3 1
M3
VS3
2
NC
3 C15 10 μF 16V
VB2 4
VS2
M2
5
NC
10
μF
16V
C16
6
VB1
7
VS1
M1
8
NC
9
DC+
V+
10
NC 11
DC12
DC13
DC14
H1
PWM1
15
H2
PWM3
16
H3
PWM5
17
L1
PWM0
18
L2
PWM2
19
PWM4
L3
20
ITRIP
21
VCC
+15V
22
R23
VSS
23
4.3K
U4
AN967
POWER SECTIONS AND MOTOR CURRENT MEASUREMENT (SHEET 2 OF 2)
DS00967A-page 15
AN967
NOTES:
DS00967A-page 16
© 2005 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
•
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED,
WRITTEN OR ORAL, STATUTORY OR OTHERWISE,
RELATED TO THE INFORMATION, INCLUDING BUT NOT
LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE,
MERCHANTABILITY OR FITNESS FOR PURPOSE.
Microchip disclaims all liability arising from this information and
its use. Use of Microchip’s products as critical components in
life support systems is not authorized except with express
written approval by Microchip. No licenses are conveyed,
implicitly or otherwise, under any Microchip intellectual property
rights.
Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, microID, MPLAB, PIC, PICmicro, PICSTART,
PRO MATE, PowerSmart, rfPIC, and SmartShunt are
registered trademarks of Microchip Technology Incorporated
in the U.S.A. and other countries.
AmpLab, FilterLab, Migratable Memory, MXDEV, MXLAB,
PICMASTER, SEEVAL, SmartSensor and The Embedded
Control Solutions Company are registered trademarks of
Microchip Technology Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, dsPICDEM,
dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR,
FanSense, FlexROM, fuzzyLAB, In-Circuit Serial
Programming, ICSP, ICEPIC, MPASM, MPLIB, MPLINK,
MPSIM, PICkit, PICDEM, PICDEM.net, PICLAB, PICtail,
PowerCal, PowerInfo, PowerMate, PowerTool, rfLAB,
rfPICDEM, Select Mode, Smart Serial, SmartTel and Total
Endurance are trademarks of Microchip Technology
Incorporated in the U.S.A. and other countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2005, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received ISO/TS-16949:2002 quality system certification for
its worldwide headquarters, design and wafer fabrication facilities in
Chandler and Tempe, Arizona and Mountain View, California in
October 2003. The Company’s quality system processes and
procedures are for its PICmicro® 8-bit MCUs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
© 2005 Microchip Technology Inc.
DS00967A-page 17
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10/20/04
DS00967A-page 18
© 2005 Microchip Technology Inc.
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