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UM0243
User manual
Universal motor control starter kit
Introduction
The UMC Starter Kit is considered to be a complete reference system for the universal
motor drive. From a hardware and software point of view, the kit is ideal for the development
of universal motor driving or, more generally, the development of phase angle control. With
the supplied PC GUI, the control type can be chosen between open or closed loop (PI
controller) and the control parameters easily modified.
The whole system consists of two boards (main and PC interface boards) and the PC GUI
software which also serves to get measurements from the board such as current, firing
angle, speed.
December 2006
Rev 2
1/29
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Contents
UM0243
Contents
1
Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2
Phase control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3
Description of parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4
PC software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1
5
6
Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.1
Stand alone mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.2
PC driven mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.3
Frequency measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.4
Open and closed loop control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Hardware description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1
Testing points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.2
Current sense and overcurrent detection . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.3
Using BTA12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6.4
Working at 60Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
7
Temperature limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8
Package contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
9
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
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UM0243
1
Getting started
Getting started
Warning:
The Kit is not electrically isolated from the AC input. The MCU
is directly linked to the mains voltage. No insulation is
ensured between the accessible parts and the high voltage.
The STEVAL-IHM007V1 Kit must be used with care and only
by persons qualified for working with electricity at mains
voltage levels. All measurement equipment must be isolated
from the mains before powering the board.
When using an oscilloscope with the Kit, it has to be isolated
from the AC line. This prevents a shock from occurring as a
result of touching any SINGLE point in the circuit, but does
NOT prevent shocks when touching TWO or MORE points in
the circuit.
When programming the MCU through the In-Dart connector,
make sure the board is plugged into an insulated mains plug
to avoid computer damage.
For correct operation of the UMC Starter Kit, use the following procedure (please refer to
Figure 1 and Figure 2):
1.
Connect the two boards using the appropriate connector (SCI);
2.
Connect the PC interface board to the PC serial port through a serial connector;
3.
Power on to the PC interface board through JP2 or J3(5V) connector (PC interface
board);
4.
Attach jumper J4 (HW[Stand Alone] / SW[PC-driven]) on the main board;
5.
Connect the motor to the Motor connector (main board);
6.
Connect the motor feedback sensor to JP4 / Hall Sensor(Hall Effect Sensor) or
J5 / Tacho(Tachometer) connectors (main board);
7.
Put a jumper on SW2/Hall Tacho depending on the speed sensor used, according to
the silkscreen (main board);
8.
Connect the mains power to Mains connector (main board);
9.
Open UMC Application window. From the Options software button, set the serial port
and the basic / advanced user mode (see Software help for further details);
10. Click Connect software button. Now the kit is ready to be driven by the GUI.
In stand alone use, skip steps 1, 2, 3, 4 (no jumper on J4), 9 and 10, regulate the speed
through the potentiometer POT1 (speed increases in a clockwise direction) before
connecting (switching on) the main power. The motor will start running according to the
default parameters and to the potentiometer value. Push SW3 ON/OFF switch to turn off
(on).
The following figures show the block diagrams of the Main board and the PC Interface.
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Getting started
UM0243
Figure 1.
Main board layout
Tacho
Hall sensor
J5
JP4
SW2
Hall/Tacho
ON/OFF
button
Fuse
ST7LITE35
POT1
General
Switch
ICC
connector
®
Figure 2.
MAINS
connector
SCI
connector
Motor
connector
PC interface board layout
Main board
Connector
Optocouplers
PC Serial
Connector
ST3232
JP2
Power Supply
Connector
Isolated
DC/DC
Supply
J3 Power
Aux Connector
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Cooling area
Sensing amplifier
(bottom side)
ACST8
HW/SW
J4
Capacitive
Power
Supply
UM0243
2
Phase control
Phase control
The speed control of universal motor in AC mode is performed by varying the firing angle
delay of a triac, thus varying the RMS voltage seen by the motor.
In detail, the triac is switched on after the mains voltage zero crossing with a delay between
0° and 180°, that is between 0 and 10 ms if working at 50Hz, or 0 and 8.3ms if working at
60Hz. The current is thus supplied from the mains to the load for a part of each half mains
period: the current starts flowing through the load as soon as the triac is turned on and is
stopped at the next triac current zero crossing. The power fed to the load varies depending
on the firing angle delay: the lower the angle, the higher the power. The kind of control
performed is symmetrical, i.e. the firing angle is kept constant within a period of the mains
voltage.
Figure 3.
Phase angle partialization
Pulse Length
Firing Angle
Zero Crossing
TRIAC Driving
Control Signal
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Description of parameters
3
UM0243
Description of parameters
In PC-driven mode all the parameters can be changed in real time (see: Section 4 on page
8). However, when the system works in stand alone mode, parameters such as maximum
and minimum firing angles, pulse length, maximum current allowed, soft start duration, cycle
change duration, open loop (OL) or closed loop (CL) control, target angle (if in OL), target
speed (if in CL), minimum and maximum speed (CL) are set in the UMC.h file.
These default values can be modified in the UMC.h file, after which the project should be
rebuilt and the microcontroller reprogrammed. Otherwise, the only parameters that can be
changed while the program is running are the target angle (OL) or the target speed (CL),
and this can be obtained by rotating the potentiometer POT1 on the main board (see
Figure 1).
Below is a brief description of the parameters:
●
Soft Start: this expresses in how many periods of Mains the Firing Angle reaches the
Target Angle starting from Alpha Max angle.
●
Pulse Length: duration of the firing pulse; the range is [50: 500] µs
●
Measured Current: selects the type of current measurement: on the mains zero
crossing or the maximum value.
●
Current limitation: if the selected current measurement type is Max current, this value
sets the maximum allowed current flowing through the motor. If the load current
reaches this value for a time longer than 1.5ms the motor is stopped. The user should
be aware that the current is measured only during the positive wave of current if the
selected measured current is the maximum value.
●
Alpha Min: minimum firing angle allowed; range [4° : (Alpha Max-1)].
●
Alpha Max: maximum firing angle allowed; range [(Alpha Min+1) : 167°(50Hz),
162°(60Hz)].
●
Soft Variation: it expresses in how many periods of Mains the Firing Angle (OL) or the
target speed (CL) reach a new Target Angle (OL) or a new target speed (CL) starting
from the actual value.
●
Ki: integration factor in PI speed control (CL).
●
kp: proportional factor in PI speed control (CL).
●
Pulses Per Revolution: it indicates the number of encoder pulses per shaft round, if
this value is not correctly set, the measured speed will not be correct, thus
compromising the CL control.
●
Target Speed Min/Max: minimum/maximum target speed; the value of the changing
speed knob, in PC driven mode, and, in stand alone and CL mode, the value read from
the potentiometer change accordingly to these parameters.
●
Filtering: number of acquisitions whose average gives the measurement.
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UM0243
Description of parameters
Here follows an example of the UMC.h file with a brief description.
/******************************************************************************
File name
: C:\temp\UMC\source\umc.h
Author
: UMC GUI Application
Description
: UMC Parameters
Creation
: Monday, November 14, 2005 12:01:35
*******************************************************************************/
#ifndef __C5A1372E_D06C_47ED_AEF2_67EDD76C3079__
#define __C5A1372E_D06C_47ED_AEF2_67EDD76C3079__
#define UMC_OPEN_LOOP
#define UMC_CLOSED_LOOP
0x0001
0x0002
#define UMC_MAX_CURRENT
#define UMC_ZERO_CROSSING
/* CONTROL SETTINGS */
#define UMC_O_C_LOOP
0x0000
0x0001
UMC_OPEN_LOOP
/* This has to be changed into
UMC_CLOSED_LOOP if necessary*/
#define UMC_PULSES_PER_REVOLUTION 0x0008 /*Corresponding to parameter
Pulses Per Revolution on the GUI*/
#define UMC_SOFT_START
0x0032 /*Corresponding to parameter
Soft Start on the GUI*/
#define UMC_PULSE_LENGTH
0x00C8/*Corresponding to parameter
Pulse Length on the GUI*/
#define UMC_OVER_CURRENT
0x0080 /*Corresponding to parameter
Current Limitation on the GUI*/
#define UMC_ALPHA_MIN
#define UMC_ALPHA_MAX
#define UMC_MEASURED_CURRENT
0x000A
0x00A7
UMC_ZERO_CROSSING /* This has to be changed into
UMC_MAX_CURRENT
if necessary*/
#define UMC_SOFT_VARIATION 0x0032
#define UMC_TARGET_ANGLE
0x0000
/*Corresponding
Target Angle, knob
/*Corresponding
Target Speed, knob
#define UMC_TARGET_FREQUENCY 0x270D
#define UMC_KI
#define UMC_KP
#define UMC_CL_MIN_SPEED
loop*/
#define UMC_CL_MAX_SPEED
0x0002
0x0019
0x1388
to
of
to
of
parameter
the GUI in open loop*/
parameter
the GUI in closed loop*/
/*Corresponding to parameter
Min, close to the knob of the GUI in open
0x2710
/*Corresponding to parameter
Min, close to the knob of the GUI in open loop*/
(unsigned long)(UMC_CL_MIN_SPEED) *
#define UMC_CL_MIN_FREQ
UMC_PULSES_PER_REVOLUTION / 60
#define UMC_CL_FREQUENCY_STEP (unsigned long)(UMC_CL_MAX_SPEED - UMC_CL_MIN_SPEED) *
UMC_PULSES_PER_REVOLUTION / 60
#define UMC_FILTERING 0x0008
/*Corresponding to parameter
Filterign in the Acquisition Setting of the GUI*/
#endif /* __C5A1372E_D06C_47ED_AEF2_67EDD76C3079__ */
For parameters not described in this paragraph, please refer to UMC GUI Help.
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PC software
4
UM0243
PC software
For a better tuning of parameters and for acquisition purposes, a PC interface has been
developed. In Figure 4 and Figure 5 the Open Loop and Closed Loop windows are shown
respectively.
Please launch the UMC Setup file and follow the instructions for the software installation.
Once the software has been installed, select the correct COM port from the Options section
and click the connect button to get started with the software. Then choose the Advanced or
Basic Mode, where the latter case has a reduced set of user-parameters. Then you can
choose both the control parameters and the control mode before starting the motor.
The communication is synchronized by means of a CTS signal (hardware handshake),
which is set at a high level by firmware only when PC communication is allowed. Ensure that
this signal is correctly managed by the PC otherwise communication failures may occur.
For further details please refer to the UMC Application help.
Figure 4.
GUI - open loop mode
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UM0243
PC software
Figure 5.
4.1
Closed loop mode
Acquisition
The acquisition takes place after having pushed the appropriate button on the right side of
the GUI window. The Underflow and Overflow bars inform the user respectively whether
acquisition samples are missing (communication problems), or if the application is too slow
for samples to be processed. In the latter case the user should adjust the acquisition time by
using the Time bar (Acquisition Settings menu) if necessary. After having stopped the
acquisition, the Plot button is enabled. Clicking this button displays a plot based on the
parameters in the Acquisition Data menu, as shown in Figure 6. At the same time, a log file
containing the acquired samples of the three parameters is produced.
Note:
During start up and, in open loop, when the target angle is varied, the firing angle plot may
result in a ramp with different slopes, the first one being steeper. Actually, the firing angle
variation is linear with time and the actual slope is constant. The steeper part of the plot is in
fact due to some missing acquired sampling (both in the plot and in the log file) and this is
due to the fact that when the Set button is pushed, set and get commands are sent to the
microcontroller preventing it from sending acquired data.
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PC software
UM0243
Figure 6.
GUI - plot window
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UM0243
5
Firmware
Firmware
The development toolset used is SOFTEC STVD7 ver 3.2.1. The workspace is opened by
opening the UMC.stw file. If any modification to the source files or to the umc.h file has been
made, the project has to be rebuilt, thus generating a new umc.s19 file. This file is used to
program the microcontroller.
The firmware has been developed in order to work both in stand alone mode (HW) and in
PC driven mode (SW) depending on jumper J4. By reading the value of pin PA2 one of the
two working modes is selected. Below is a brief description of the firmware flow in the two
cases:
5.1
1.
Defaults Loading (service_routines.c): default parameters are loaded; they can be
changed by PC interface in PC driven mode.
2.
Peripheral Initialization (ADC_10bit.c, lite_timer_8bit.c, sci.c):
–
ADC → ADC on, channel converted is channel 0 (hw potentiometer).
–
Lite Timer →Input Capture and Time base (1ms) interrupts enabled for tachometer
or Hall effect sensor period measurement for motor speed computing.
–
SCI →1 Start bit, 8 Data bits, 1 Stop bit, baud rate equal to 19200.
3.
Ports Initialization (ports.c).
4.
Mains Frequency Detection (mains.c).
5.
Reading of Pin PA2 (mains.c): by means of a jumper this pin is connected to ground in
PC-driven mode or to a switch in stand alone mode.
Stand alone mode
As soon as stand alone mode has been detected, the motor is turned on.
The first interrupt request is the one coming from pin PB5, the zero-crossing mains voltage
detection pin, the sensitivity has been set so that both rising and falling edges of the signal
generate the interrupt request. As soon as this interrupt is served, the PWM AR Timer is
switched on in order to start counting the firing angle delay and then, if a falling edge occurs,
the Analog to Digital Converter is set in order to convert the value coming from the
potentiometer. Otherwise, on the rising edge, the A/D converter is configured for the current
measuring and if required, the soft variation of the firing angle is implemented.
The triac activation is controlled by PWM AR Timer. On its interrupt routine, the
measurement of the period maximum current is also performed. A flowchart for stand alone
mode is shown in Figure 7.
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Firmware
UM0243
Figure 7.
Firmware flowchart - stand alone mode
Start:
Ports & Peripheral
Initialization
Mains freq
detection
PA2 set ÆStand Alone Mode
Pin PA2
reading
Motor ON
PA2 interrupt
Compute new angle/speed
from potentiometer reading
Conversion PeriodÆ freq
Waiting for interrupt
PB5 falling edge (ZVS)
Pot reading
Motor ON/OFF
PWM/AR Timer interrupt
Soft start/soft variation management
TRIAC turn ON
Over Current Computing
Compute potentiometer mean
5.2
Lite Timer interrupt
Period Measurement
PC driven mode
The flow chart during PC driven mode is shown in Figure 8.
Compared to the stand alone mode, here the SCI communication handling is present.
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UM0243
Firmware
Figure 8.
Firmware flowchart - PC driven mode
Start:
Ports & Peripheral
Initialization
Pin PA2
reading
PB5 falling edge (ZVS)
PA2 reset ÆPC GUI driven Mode
SCI communication
handling
PI control each 10ms (if CL)
Conversion PeriodÆ freq
Waiting for interrupt
Current measurement (if ZC current)
Acquired frame transmission (if in
acquisition)
SCI interrupt
Set SCI flag
(Communication
handled on main
routine)
PB5 rising edge (ZVS)
CTS Enable
Soft start/soft variation management
PWM/AR Timer interrupt
TRIAC turn ON
Over Current Computing
CTS Disable
Lite Timer interrupt
Period Measurement
5.3
Frequency measurement
The reading of the motor speed is achieved in two steps. First, the period measurement is
performed thanks to the Input Capture feature of the 8-bit Lite Timer, and then a period to
frequency conversion is executed.
When a transition on the feedback signal (tachometer or Hall sensor) occurs, an interrupt is
generated by the Lite Timer peripheral and the value of the Lite Timer counter is latched in
the LTICR register. In order to make the system less sensitive to eventual dissymmetry on
the signal duty-cycle, only high to low transitions are taken into account.
The Lite Timer Input Capture (LTIC) feature of the Lite Timer, together with the possibility of
generating an interrupt when the upcounter overflows (LTTB1 Interrupt), precisely measures
the period of the Hall sensor signal.
Considering, in fact, Figure 9, it is possible to draw the following mathematical relationship:
TH = ((250 − Capture 1) + Capture 2 + 250 ⋅ ( N − 1)) ⋅
32
f OSC
N >0
(5.3.1)
where TH represents the feedback signal period, Capture 1 and Capture 2 indicate the
values of Counter 1 at the edges of the Hall sensor signal and N is the number of LTTB1
interrupt events between the two feedback signal falling edges taken into account.
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Firmware
UM0243
Figure 9.
Feedback signal semi-period measuring (N>0)
LTTB1 Int
LTTB1 Int
LTTB1 Int
249
Counter1
Capture 1
Capture 2
t
LTIC Int
LTIC Int
LTIC Int
(Discarded)
Hall sensor
output
t
The relation (5.3.1) is valid only under the condition N>0 and therefore it can not be used to
measure frequencies higher than 500Hz. In this case the formula to be used, deduced by
observing Figure 10, is (5.3.2) :
Figure 10. Hall sensor signal semi-period measuring (N=0)
249
LTTB1 Int
LTTB1
LTTB1
Capture 2
Counter1
Capture 1
LTIC Int
LTIC Int
LTIC Int
t
Hall sensor
output
t
TH = (Capture 2 − Capture 1) ⋅
32
f OSC
(5.3.2)
Note that in both (5.3.1) and (5.3.2) TH is computed with a resolution equal to
is 4 µsec at 8MHz fOSC.
32
which
f OSC
It can be seen that in order to measure the Hall sensor semi-period correctly, the LTIC and
LTTB1 ISRs must be executed by the microcontroller core in the same order in which the
related interrupts events occurred. This would normally happen if no other interrupts service
routines are executing. However in our software, a third interrupt source is enabled (PWM
update event), so a potentially erroneous situation could arise due to the interrupt priority
mechanism.
Figure 11 describes two possible situations when multiple interrupts occur:
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UM0243
Firmware
Figure 11. Multiple interrupt pending situation
LTTB1
LTTB1
249
249
Captured
value << 125
Counter 1
Captured
value >> 125
Counter 1
t
t
LTIC Int
LTIC Int
Hall sensor
output
t
PWM OVF ISR execution
t
t
PWM OVF ISR execution
t
Due to the higher interrupt priority of LTIC with respect to LTTB1, in both cases the LTIC ISR
is executed before LTTB1 ISR.
In this case, the value stored in the LTICR is used to reconstruct the correct sequence. If the
content of the LTICR is lower than 125, it is assumed that the LTTB1 event occurred just
before an LTIC event so that the Lite Timer overflow counter must be incremented before the
semi-period computation. However, if the LTICR contains a value higher than 125, it is
assumed that the LTIC occurred just before a Lite timer overflow (LTTB1 event). In this case,
the overflow counter must not be incremented before the semi-period computation but it will
be taken into account at the next LTIC event.
After the period measurements have been carried out, they are stored in the measure array,
whose depth is equal to the parameter "filtering".
Successively, in the main loop, an average of the stored measurements is performed and
the period to frequency conversion is carried out. Function Compute_division( ) provides
conversion optimization in terms of execution time for frequencies higher than 35Hz.
5.4
Open and closed loop control
When the Open Loop control strategy is selected, the firing angle is the control parameter. It
can be changed by potentiometer in Stand Alone Mode or by a control in the PC GUI (refer
to Figure 4) if PC-driven.
However, when the Closed Loop control strategy is selected, the control parameter is the
target speed. In this case, in order to make the actual speed equal to the target speed by
adjusting the firing angle, a PI controller has been implemented. The general formula for an
analog PI regulator is:
t
u (t ) = K P * e(t ) + K I * ∫ e(τ )dτ
(5.4.1)
0
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Firmware
UM0243
where:
u(t) is the driving signal
e(t) is the error signal, difference between the actual feedback frequency and the target
feedback frequency.
Kp, K1 are respectively the proportional and the integral constants.
In the case of digital regulators the above equation becomes:
n
u (n ) = K P * e(n ) + K I * T * ∑ e(i )
i =0
(5.4.2)
where:
u(n) is the driving signal sampled at the instant nT
e(n) is the error signal sampled at the instant nT
Kp, K1, KD are respectively the proportional and the integral constants
T is the sampling time.
We can also write:
n +1
u (n + 1) = K P * e(n + 1) + K I * T * ∑ e(i )
i =0
(5.4.3)
and, subtracting equation (5.4.3) from (5.4.2):
n
⎡ n +1
⎤
u (n + 1) − u (n ) = K P * [e(n + 1) − e(n )] + K I * T * ⎢∑ e(i ) − ∑ e(i )⎥
i =0
⎣ i =0
⎦
simplifying:
∆u (n ) = K P * ∆e(n ) + K I * T * e(n )
(5.4.4)
Equation (5.4.4) shows the variation of the firing angle ∆u (n ) at the instant nT due to the
error in the same instant (term e(n ) ) and to its variation at the instants nT and (n-1)T
(terms ∆e(n ) and ∆e(n ) − ∆e(n − 1) ).
[
]
In the "PI" routine, the error is first computed and based on it, the variation of the firing angle
is calculated according to equation (5.4.4).
The coefficients must be adjusted for a given motor type. This can be easily achieved with
the PC GUI.
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UM0243
6
Hardware description
Hardware description
Two separate boards have been developed: the main board and the PC interface one. In
Figures 13 and 14 the schematics of the boards are shown.
At first glance, the main characteristics are:
●
A capacitive power supply to reduce the overall cost of the system. This supply can
source an average current lower than 20mA.
●
Control Unit consisting of an ST7Lite35 device and external circuitry.
●
An ACST8-8C AC Switch. This device is driven by means of a bipolar transistor in
order to guarantee the proper working in the whole extended temperature range using
only one MCU pin. In fact the turn-on current needed is equal to 35mA in nominal
conditions, but it increases up to 70mA for a -20°C junction temperature. Nevertheless
if no further MCU pins are needed for other purposes, the ACST switch can be directly
driven using 3 HS pins connected in parallel. A noise suppressor (R7 and C7, see
Figure 13) has been connected in parallel with the device in order to increase
IEC61000-4-4 immunity.
●
Two speed sensor nets for a Hall effect sensor or a Tachometer.
●
A Current Sensing circuit.
●
A Zero Crossing Network providing the Control Unit with a TTL signal in accordance
with the zero crossing of the mains. This network is realized with a bipolar transistor,
but a resistor topology could also have been used (see Figure 12), but, in this case, the
firmware must handle somehow the dissymmetry compensation in order to avoid DC
current injection through the motor.
Figure 12. Resistor based ZCN
VDD
MCU
Mains
PB5
R 160K
R 160K
C 100pF
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4
3
2
1
HEADER 4
JP7
TACHO
2
1
J5
JP4
1
2
3
Hall sensor
R20
10K
R17
10K
Univ ersal motor
2
1
JP2
JP1
R19
10K
R14 10K
CTS
RXD
TXD
1N4148
D4
Vdd5
MAINS
2
1
2
R15
33K
R16
1K
BC337-25
3
Q4
1
Vdd5
C8
1n
1
TP7
R9 470K
R7 Q2
47
1
ACST8
R3
0.047R 5W
C6
1uF 220V~
C7
1n 220V
R8 470K
C13
68n
SO7K300
NC
L
10n x2
C3
8A/250V
C14
N.C.
TP7
R5
2.2K
R6
47
47
SW2
1
2
2
TP3
TP2
TP2
HALL TACHO
3
1
D3
1N4148
TP3
68
TP6
TP6
D2
1N4148
C4
1000u/10V
C2
100nF
TP5
TP5
50K
RESET
Vdd5
150nF
C9
POT
NTC
1
2
J3
Vdd5
POT
RXD
PB5/ZC
NTC pin
Current Sense
C5
100nF
Current Ref
2 Target Speed
SPEED SENSOR
POT1
Q3
BC547B
PB5/ZC
Triac driv ing
Current Ref
R22
R21
Vdd5
D1
6.2V 1W
1
F1
1
3
1
TP1
TP1
1
3
N
U1
PA0(HS)/LTIC
OSC2
OSC1/CLKIN
R18
56K
Vdd5
R12 10K
R13
100K
3
2
4
7
U2
C10
2.2nF
NTC pin
6
1
TP4
TP4
R10 100K
TS1851ID
Vdd5
ST7LITE 35
PA1(HS)/ATIC
SCK/AIN1/PB1
PA2(HS)/ATPWM0
MISO/AIN2/PB2
PA3(HS)/ATPWM1
MOSI/AIN3/PB3
PA4(HS)/ATPWM2
CLKIN/AIN4/PB4
PA5(HS)/ATPWM3/ICCDATA
AIN5/PB5
PA6/MCO/ICCCLK
RDI/AIN6/PB6
PA7(HS)/TDO
SS/AIN0/PB0
RESET
Vdd
Vss
R11 10K
10
9
8
7
6
5
4
3
2
1
11
12
13
14
15
16
17
18
19
20
HW/SW
2
1
J4
Vdd5
SCL
Current Sense
R4 22K
SW3
RESET
SDA
GPSwitch
TXD
SCL
SDA
CTS
ON/OFF
1
2
3
4
5
6
7
8
9
10
10nF
C11
ON/OFF
J2
SW4
GPSwitch
Triac driv ing
Q1
3 BC547C
1
Programming Interf ace
2
R1
100K
Vdd5
2
C1
1n
2
1
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1
SPEED SENSOR
+
-
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1
Hardware description
UM0243
Figure 13. Main board schematic
UM0243
Hardware description
Figure 14. PC interface board schematic
VIN
GND
U6
LM78L05ACZ
3
C8
1
VOUT
Vdd5
Vdd5
U1
ISOLATED
4 Vin DC/DC Vo 5
2
1uF
C1
+5V
+5V
1 GND
1uF / 16V
JP2
1
2
VCC5
C2
100nF 16V
7
0V
VCC5
NME0505D
0V
HEADER 2
C3
+
C4
1u / 16V
J3
1uF/16V
U2
1
2
+
C5
1uF/16V
1
2
3
4
5
6
7
8
aux-v oltage
TXD
JP1
+
C6
1uF/16V
P1
VCC
GND
T1OUT
R1IN
R1OUT
T1IN
T2IN
R2OUT
C+
V+
C1C2+
C2VT2OUT
R2IN
16
15
14
13
12
11
10
9
0V
RXD_Insulated
CTS_Insulated
RXD
4
3
2
1
ST3232/SO
CTS
1
6
2
7
3
8
4
9
5
PC Interf ace
C7
0V
+
1uF/16V
HEADER 4
Tx_Insulated
0V
VCC5
CTS
Vdd5
VCC5
VCC5
R101
R3
10K
RXD
Vdd5
2.2K
R4 1K
R100
1
4
U4
U5
2
3
Tx_Insulated
2
SFh615A
R2
1K
4
1.8K
TXD
R1
2.2K
CTS_Insulated
1
4 U3
1
3
RXD_Insulated
2
3
SFh615A
SFH615A
0V
0V
In Figure 15 the picture of the main board shows the main parts.
Figure 15. Main board
1
2
3
4
5
6
7
8
10
Note:
9
See below for a description of labeled board components.
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Hardware description
1.
Tachometer sensor connector
2.
Hall Effect sensor connector
3.
Off/On push button (only in stand alone mode)
UM0243
4.
This jumper detects stand alone(no jumper present)/pc driven mode (jumper present)
5.
Potentiometer for speed/ firing angle changing (if the system works in stand alone
mode)
6.
General switch
7.
PC interface connector
8.
NTC connector
9.
Motor connector
10. Mains power connector
11. Testing points
6.1
Testing points
Some testing points are present on the board thus allowing the user to directly obtain and
measure waveforms. Here follows a list of these points and of the expected waveforms.
●
TP1: Vdd - 5V
●
TP2: ground
●
TP3: zero crossing signal - 0:5V square wave at 50 or 60Hz
●
TP4: current sense (output signal of the OP-Amp) - see Figure 16, 17, 18
●
TP5: speed sensor feedback - see Figure 20
●
TP6: triac driving signal - see Figure 21
●
TP7: ACST8 output - see Figure 22, 23
In all the figures below, channel C1 represents the zero crossing signal (@ 50Hz) and
channel C3 pin PA4, i.e. the triac driving signal before the transistor, this in order to give an
idea of the firing angle used in the examples.
Besides the waveforms on the testing points, Figure 19 has been added in order to show the
current on the ACST switch.
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UM0243
Hardware description
Figure 16. TP4 - Current Sense Signal (C2), 168° firing angle.
Note:
The signal is different from zero only during half a period of the mains waveform.
Figure 17. TP4 - Current Sense Signal (C2), firing angle is decreasing
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Hardware description
UM0243
Figure 18. TP4 - Current Sense Signal (C2), 6° firing angle
Figure 19. C1 - zero crossing signal. C2 - ACST driving signal. C4 - ACST switch
current.
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UM0243
Hardware description
Figure 20. TP5 - Speed sensor feedback signal (C2), 3500 RPM
Figure 21. TP6 - Triac Driving Signal (C2)
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Hardware description
UM0243
Figure 22. TP7 - ACST Output-COM voltage (C2) with firing angle equal to 167°
Figure 23. TP7 - ACST Output-COM voltage (C2) with firing angle equal to 90°
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UM0243
6.2
Hardware description
Current sense and overcurrent detection
The voltage created by the current flowing through the sensing resistor R3 (0.047 Ohm) is
amplified by ten so that the maximum detectable current is about 10A. The protection
against overcurrent only takes place when the max current instead of the zero crossing
current is measured. This parameter can be changed by software or, in stand alone mode,
by modifying the umc.h file. In case the max current is the parameter measured, the value is
acquired each 500µs and the protection takes place (motor is switched off) only if three
consecutive values exceed the maximum allowed, this is in order to reduce measurement
noise.
Measurement of maximum current is carried out during main power's positive half
waveform.
6.3
Using BTA12
It's possible to place a BTA12-800CW (12 Amps RMS) Triac instead of the ACST8-8C. In
this case a S07K300 varistor must be connected in parallel with the triac for over-voltages
protection (see Figure 24).
Figure 24. Schematic variation when BTA12 is used.
N
R22
0.047
Current Ref
R19
R26
1n
BTA12-800CW
Q9
Triac driving
56
U
S07K300
J4
47
1
2
Universal motor
6.4
Working at 60Hz
Please note that the kit works at 60Hz under nominal voltage supply conditions (i.e. 110V).
For lower voltage values the capacitive power supply stage has to be modified, since it has
been designed to work in the range 110V/230V.
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Temperature limitation
7
UM0243
Temperature limitation
Since the microcontroller uses its internal oscillator and PLL, which are temperature
dependent, and since the system's correct behavior is strictly related to the oscillation
frequency, the system has to be considered to operate in the temperature range that
involves a maximum frequency deviation of:
●
±3% from the nominal 8MHz frequency if working at 50Hz or
●
-2%:+3% from the nominal 8MHz frequency if working at 60Hz
For higher frequencies the SCI communication with the PC fails, but the control still operates
correctly.
Otherwise, the microcontroller needs to be recalibrated or an external oscillator must be
used. Automatic real time calibration can also be implemented (refer to AN1324 for further
information).
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UM0243
8
Package contents
Package contents
The following material is supplied in the package:
●
UMC Main board
●
PC interface board
●
One connector main board - PC interface board
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Revision history
9
UM0243
Revision history
Table 1.
Document revision history
Date
Revision
Changes
08-Sep-2006
1
Initial release.
14-Dec-2006
2
Safety warning added Section 1 on page 3
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UM0243
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