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November 2012 Doc ID 023542 Rev 1 1/13
UM1559User manual
STEVAL-IHM041V1: hardware description
IntroductionThe STEVAL-IHM041V1 is a Triac based phase angle control for universal motor speed control using an STM8S103F3, 8-bit microcontroller, to set the conduction angle of the Triac. The board may be operated in either open loop mode or in closed loop speed control mode, with an AC tach, hall sensor or opto sensor feedback. The open loop mode may also be used as a lamp dimmer.
The board is designed to operate from a 120 V/60 Hz mains, but may be easily modified to operate on other mains voltages by changing components in the power supply and motor voltage sensing circuits. Suggested component values for other mains voltages are shown in the alternate bill of materials.
On power-up, the firmware determines if jumper J4 is installed or not. The board operates in open loop mode if J4 is not installed and in closed loop mode if J4 is installed. When operating in closed loop mode, an AC tach or a hall effect device is connected to J3 to provide speed feedback.
Figure 1. Board image
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Contents UM1559
2/13 Doc ID 023542 Rev 1
Contents
1 Main features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Schematic and bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Circuit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
UM1559 List of figures
Doc ID 023542 Rev 1 3/13
List of figures
Figure 1. Board image . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Figure 2. STEVAL-IHM041V1 schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Figure 3. Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Figure 4. Voltage sensing circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Figure 5. Tachometer interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Main features UM1559
4/13 Doc ID 023542 Rev 1
1 Main features
● Input voltage 120 V/60 Hz
– 230 V/50 Hz (with component change)
● Motor current 7A RMS
● Phase control for universal motor drive
● Open loop or closed loop speed regulation
● Voltage and current sensing, for sensorless operation (optional)
● Debug outputs
● AC tach, hall sensor or opto sensor for speed feedback.
UM1559 Schematic and bill of material
Doc ID 023542 Rev 1 5/13
2 Schematic and bill of material
Figure 2. STEVAL-IHM041V1 schematic
AM12468v1
PB3
DN
IG
ND
PB2
DN
IPB
1
PB1
PB2
PB3
1 2
J2
TX
115V
AC
CO
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ICAT
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gnd
2
gnd
3
NC
4N
C5
gnd
6
gnd
7
in8
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7805
AC
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47
C4 470F
10V
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D
R16
0.01
10VZ1
5V
Q1
T163
5T
C10.
22uF
gate
6 57
- +8 4U
1B
R13 1K
R11
22K
R7 100K
ZC
R17
5K5V
C3 220u
F 10
V
MO
TO
R C
ON
NE
CT
ION
PO
WE
R S
UP
PLY
R8 100K
R14
100K
R19
47K
1 2 3 4
J1
swim
C5 0.22
uF
GN
D
5V
C60.
22uF
LED
5D
NI
pd4
1
tx2
rx3
nrst
4
osci
n5
osco
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7
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8
Vdd
9
pa3
10pb
511
pb4
12
pc3
13
ain2
14
pc5
15
pc6
16
pc7
17
swim
18
ain3
19
ain4
20 U4
STM
8S10
3F3P
6
GN
D5V
swim
TX
R18
2.2K
R25
2.2K
PB1 PB
2
PB3
ZCVFB
R26
2.2K
R20
100
R21 10
0R2
2
2.2K R
23 2.2K
LED
3 DN
I
LED
2Re
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LED
4
DN
I
LED
1
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I
gate
5V
5V
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5V
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ENT
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G
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2 31
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R10
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9K
R239
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231
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84
U3A
LM39
3
R24
10K
5V
R30
10VF
BC7 47
nF
GN
D
1234
J3
R32
10K
5V
R31
2K
R28
22K
5VR3
3
10K
R29
2K
R27
200K
TAC
HO
ME
TE
R I
NT
ER
FAC
E
R12
MO
V
1TP1
1
TP2
D1
1N41
48
D2
D3
C2
2.2u
F 25
0V
1 2
P1
1 2
J4
Schematic and bill of material UM1559
6/13 Doc ID 023542 Rev 1
Table 1. BOM
Designator Part/value Manufacturer Manufacturer part no.
C1 0.22 µF
C2 2.2 µF 250 V Panasonic EF2225
C3 220 µF 10 V
C4 470 µF 10 V
C5, C6 0.22 µF
C7 47 nF
D1,D2, D3 1N4148 Diodes Inc 1N4148FDICT
J1, J3 4Pos .100 header
J2 2Pos .100 header
J4 2Pos .100 header
LED2 Red LED
LED1, LED3, LED4, LED5
DNI
P1, P2 2Pos locking 5 mm
PB1
PB2, PB3 DNI
Q1 T1635T STMicroelectronics T1635T-81
R1, R13, 1 kΩ
R14 100 kΩ
R2, R3, R5, R6 39 kΩ
R4 DNI
R7, R8 100 kΩ
R9, R10, R29, R31 2 kΩ
R11, R28 22 kΩ
R12 MOV Epcos S14K275
R15 47 Ω
R16 0.01
R17 5 kΩ pot
R18, R22, R23, R25, R26
2.2 kΩ
R19 47 kΩ
R20, R21 100 Ω
R24, R32, R33 10 kΩ
R27 200 kΩ
R30 10 Ω
UM1559 Schematic and bill of material
Doc ID 023542 Rev 1 7/13
TP1, TP2 Test point
U1 TSV358IYDT STMicroelectronics TSV358IYDT
U2 L7805AC STMicroelectronics L7805ACD2T-TR
U3 LM393 STMicroelectronics LM393AD
U4 STM8S103F3P6 STMicroelectronics STM8S103F3P6
Z1 10 V
Table 2. Alternate bill of materials for 230 V/50 Hz operation
Designator Value
C2 1 µF, 400 V
R2, R3, R5, R6 82 kΩ
Table 1. BOM (continued)
Designator Part/value Manufacturer Manufacturer part no.
Circuit description UM1559
8/13 Doc ID 023542 Rev 1
3 Circuit description
Power supply
The power for the STM8 and the associated control circuit is derived from the mains input using a capacitive drop power supply followed by a 5 V linear regulator, as shown in Figure 3.
Figure 3. Power supply
C2, R15, Z1, D1 and C4 form the capacitive drop supply that provides an unregulated 10 V to the L7805 linear regulator. Zener diode Z1 sets the peak value of the unregulated supply. A value of 10 V was chosen to maintain the minimum voltage of 8 V at the input of the L7805. The power supply section was designed to use with a 120 V/60 Hz mains. The power supply can be modified to be used on 230 V/50 Hz mains by changing C2. Component changes needed to modify the board to work on a 230 V/50 Hz mains are shown in Table 2.
Line sync interface
To synchronize the gate drive for the Triac to the AC mains, the STM8 senses the zero crossings of the AC mains voltage at the timer1 capture input. A pair of series current limiting resistors, R1 and R2, connect the AC line input to the timer1 capture input pin. Two 1206 case resistors are used in series to provide sufficient voltage rating. The voltage at the pin is clamped to 5 V and ground by the internal diodes in the STM8. The values of the resistors are selected to limit the current to within the allowable range for the STM8.
Triac power stage
Triac Q1 is connected in between the mains and the load and functions as a phase controlled switch to provide power to the motor. The gating signal is generated by the STM8 at GPIO pins PC6 and PC7. The pins are paralleled in order to increase the available gate current drive and the control must operate these two outputs in unison.
For best operation, the Triac should be operated in the second and third quadrant, always using a negative pulse on the gate to turn the device on. Since the STM8 operates from a positive 5 V supply, it is not possible to directly drive the gate with a negative pulse. Capacitor C1 AC couples the gate signal from the STM8 to the Triac so that a falling edge on the output of PC6 and PC7 generates a negative voltage on the Triac gate for turn-on. The
AM12564v1
115VAC
out1
gnd2
gnd3
NC4
NC5
gnd6
gnd7
in8
U2
L7805AC
1
2
P2
R15
47
C4
220uF 10V
GND
Z1
10V
5V
C3
470uF 10V
D1
1N 4148
C2
2.2uF 400V
UM1559 Circuit description
Doc ID 023542 Rev 1 9/13
example control software provides a series of “picket fence” pulses to the gate, to improve the reliability of the gating, always finishing with the pins back high, ready for the next gating.
Current sensing
Shunt resistor R7 is used to sense the motor current during the Triac conduction angle. Using a value of 0.01 Ω generates a signal that is 10 mV/A. This signal is amplified by U1 to get a signal of 220 mV/A that is fed into an ADC input of the STM8. With a 5 V full scale value on the ACD, the circuit can read peak currents up to 22.7 A.
Although the current through R7 is both positive and negative, the inverting configuration circuit amplifies only the negative current since the amplifier output cannot go below ground. An alternate configuration would be to add a bias to the amplifier circuit so that at zero current the output would be half of the full scale voltage, or 2.5 V. In this way both positive and negative current may be measured but the peak current capability would be reduced by ½ if the gain stayed the same.
The current sensing is included primarily for a sensorless speed control algorithm. The algorithm senses current during the negative half cycle and performs the speed regulation calculations during the positive half cycle.
The current sensing is not needed for the open loop or closed loop speed control with tachometer feedback.
Motor voltage sensing
Figure 4. Voltage sensing circuit
The measured motor voltage is also required for a sensorless speed estimation algorithm of the software. Since neither side of the motor terminal voltage is at ground potential, a conventional differential amplifier stage, built around U1A, is used to interface the signal to the ground referenced STM8 ADC input, as shown in Figure 4. The differential amplifier also provides attenuation, biasing and resistive isolation. The gain of this circuit is 1 kΩ/78 kΩ. Since the circuit is biased at 2.5 V out for 0 V in, the input voltage range is +/- 195 V peak over the full scale range of 0 to 5 V on the ADC input.
Two 1206 case resistors are used in series for the input resistors to provide sufficient voltage rating. For operation on 230 V/50 Hz mains, the values of input resistors R2, R3, R5 and R6 are changed to 82 kΩ.
Circuit description UM1559
10/13 Doc ID 023542 Rev 1
The voltage sensing is not needed for the open loop or closed loop speed control with tachometer feedback.
Potentiometer
PCB mounted potentiometer R8 is connected between 5 V and ground with the wiper providing an input signal to STM8 ADC input Ain4. This can be used as a general analog input signal. In the example software, this signal is used as either a closed loop speed command or an open loop gating phase angle command.
Tachometer interface circuit
For closed loop speed control, a tachometer signal can be connected to connector J3. The circuit supports a pure magnet pickup coil type, a hall sensor type pulse tachometer or an opto interrupter or reflector type of pick-up.
Figure 5. Tachometer interface
For active devices like a hall sensor or opto pick-up, the 5 V power supply and ground is available on pins 1 (GND) and 4 (5v) and the device output should be connected to pin 3. A pull-up resistor, R28, is provided for open collector devices, but totem pole outputs can be accommodated as well.
For AC pick-up coil type devices, the output wires should be connected at pins 2 and 3. The differential signal is biased to approximately 1/2 of the supply voltage and diodes D2 and D3 clamp the signals to safe levels for the comparator inputs. A small hysteresis in the comparator should still provide sufficient sensitivity for low speed operation. The sensitivity can be improved by removing the pull-up resistor R28, which is not actually needed for the AC tach.
The example software requires a setting of the number of pulses (rising and falling edges) per rotation to scale the speed calculation.
User and debug interface
Connector J1 is the standard 4-pin SWIM connector for programming and debug connections.
Up to three pushbuttons can be installed to provide simple command inputs. The standard board configuration populates only PB1, which is used by the example software as a start/stop command. The other two pushbuttons may be installed and used by user
UM1559 Circuit description
Doc ID 023542 Rev 1 11/13
developed software. Jumper J4, used by the example software, is connected in parallel to PB3, so either J4 or PB3 may be used.
The board layout allows for up to 5 LEDs that user developed software can use. Only LED2 is populated on the standard configuration board and the example software uses it to display motor on/off status.
The two outputs on pins 11 and 12 of the STM8 were designed for a dual function. If a 10uF capacitor is installed in the position marked for LED3 and LED5, the signal on the positive terminal of each capacitor can be used as a diagnostic analog output. The capacitor, along with the 2.2 kΩ series resistor, forms a low pass filter that filters the PWM output from the STM8 to provide a simple DAC function. The example software uses these two PWM outputs to provide useful analog diagnostic signals that can be displayed on a scope. By default, the RPM command (before accel/decel slew limiting) and actual speed are presented. These signals can also be observed at the test points without the capacitors as a pure PWM signal.
Note: The circuit ground of the PCB is “hot” with respect to the AC mains so it is necessary to operate the board from an isolated supply, such as an isolation transformer, or use an isolated input oscilloscope to make these observations. This warning also applies to the connection of a PC to the swim connector. The board must be powered by an isolation transformer or the connection to the programming dongle must be through an isolating interface.
Connector J2 is provided to give a serial data output from the UART that may be used for diagnostics to send data to another board. The example software does not use this function.
Revision history UM1559
12/13 Doc ID 023542 Rev 1
4 Revision history
Table 3. Document revision history
Date Revision Changes
28-Nov-2012 1 Initial release.
UM1559
Doc ID 023542 Rev 1 13/13
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Figure 1. Board image1 Main features2 Schematic and bill of materialFigure 2. STEVAL-IHM041V1 schematicTable 1. BOMTable 2. Alternate bill of materials for 230 V/50 Hz operation
3 Circuit descriptionFigure 3. Power supplyFigure 4. Voltage sensing circuitFigure 5. Tachometer interface
4 Revision historyTable 3. Document revision history