ST STEVAL-ISF003V1 User manual

July 2016
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www.st.com
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User manual
Getting started with the STEVAL-ISF003V1
Introduction
The STEVAL-ISF003V1 evaluation board allows the inrush-current which charges a DC bus capacitor to
be limited to comply with standard IEC 61000-3-3. This inrush current limitation is based on a soft-start
procedure of the mixed bridge diodes and SCRs rectifier using progressive phase control at board start-
up.
This solution can also drastically reduce standby losses as the DC bus can be totally disconnected from
the AC mains when it does not have to operate. DC bus deactivation is simply achieved by turning off
SCRs, without requiring an additional relay to open the circuit in standby.
The steady-state losses are also reduced, thanks to the removal of the NTC / PTC resistor traditionally
used to limit inrush current. Also in this case, no relay is required to bypass this resistor as it is no longer
used.
Figure 1: STEVAL-ISF003V1 board (top view)

Contents
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Contents
1Demonstration board overview......................................................6
1.1 What does this demoboard aim to demonstrate?..............................6
1.2 STEVAL-ISF003V1 functional blocks................................................6
1.3 Target applications............................................................................7
1.4 Main part numbers............................................................................7
1.5 Operating range................................................................................7
1.6 Performance characteristics..............................................................8
1.7 Standby consumption........................................................................9
2Getting started...............................................................................11
2.1 Safety instructions...........................................................................11
2.2 Board connection and start-up........................................................11
2.3 DC bus capacitor discharge for demonstration purposes................13
2.4 LED indications...............................................................................13
2.5 Possible board variations................................................................14
2.5.1 EMI filter and DC bus capacitor alteration........................................ 14
2.5.2Power factor circuit connection ........................................................ 14
2.5.3 Motor inverter connection................................................................. 15
2.5.4 Control with an external microcontroller........................................... 15
3Schematic diagrams......................................................................17
4STEVAL-ISF003V1 power supplies and typical consumption....20
5Inrush-current limitation...............................................................22
5.1 IEC 61000-3-3 overview..................................................................22
5.2 STEVAL-ISF003V1 compliance with the IEC 61000-3-3 limit.........22
6Mains voltage dips and interruptions ..........................................26
7AC voltage monitoring and zero-voltage synchronization.........30
7.1 Zero voltage and AC line voltage sensor circuits ............................30
7.2 Zero AC line voltage detection........................................................31
8SCR switch insulated control.......................................................32
9EN55014 test results .....................................................................34
10 STEVAL-IHT008V1 silk-screen .....................................................35
11 Bill of materials..............................................................................36
12 Test points.....................................................................................40

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13 Conclusion.....................................................................................41
14 Revision history ............................................................................42

List of tables
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List of tables
Table 1: Power sources from flyback converter .........................................................................................7
Table 2: Comparison of standby losses....................................................................................................10
Table 3: Typical STEVAL-ISF003V1 control-circuit consumption ............................................................20
Table 4: Maximum input RMS current variation for 230 V single-phase grid according to IEC 61000-3-3
..................................................................................................................................................................22
Table 5: Dip and interruption tests and STEVAL-ISF003V1 performance...............................................27
Table 6: Document revision history ..........................................................................................................42

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List of figures
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List of figures
Figure 1: STEVAL-ISF003V1 board (top view)...........................................................................................1
Figure 2: STEVAL-ISF003V1 functional block diagram..............................................................................6
Figure 3: Connection of a PFC at the HVDC output...................................................................................8
Figure 4: Inrush current at STEVAL-ISF003V1 start-up on 230 V line (1 mF output DC capacitor)..........9
Figure 5: Solution using relays to limit the inrush current and standby losses...........................................9
Figure 6: J1 jumper plugged on board (bypass mode).............................................................................11
Figure 7: J1 jumper position left free (phase control mode) .....................................................................12
Figure 8: AC line connections...................................................................................................................12
Figure 9: HVDC switch..............................................................................................................................13
Figure 10: PFC activation permission (PFC_Start signal) when the HV output capacitor is charged......15
Figure 11: STEVAL-IFS003V1 power and insulated control schematic...................................................17
Figure 12: STEVAL-ISF003V1 control circuit schematic..........................................................................18
Figure 13: STEVAL-ISF003V1 flyback SMPS schematic.........................................................................19
Figure 14: Typical output characteristics of the 5 V and 15 V positive supplies (5V_DC/15V_DC).........21
Figure 15: Typical output characteristics of the 5 V positive supply (VCC_AC).......................................21
Figure 16: HV capacitor charging controlled ............................................................................................23
Figure 17: SCR current zoom for the highest peak current during start-up..............................................24
Figure 18: Triac current for the highest peak current during start-up.......................................................25
Figure 19: Board operation during 1-cycle line interruption......................................................................28
Figure 20: Board operation during 2-cycle line interruption......................................................................29
Figure 21: AC line voltage measurement principle...................................................................................30
Figure 22: Zero AC line voltage crossing detection..................................................................................31
Figure 23: SCR switch insulated control...................................................................................................32
Figure 24: EMI noise test with 2000W load..............................................................................................34
Figure 25: EMI noise test with no load......................................................................................................34
Figure 26: STEVAL-IHT008V1 silk-screen...............................................................................................35

Demonstration board overview
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1 Demonstration board overview
1.1 What does this demoboard aim to demonstrate?
The STEVAL-ISF003V1 is a standalone board designed to demonstrate efficient trade-offs
regarding:
inrush-current limitation without inrush-current resistors
standby losses in line with ECO European directive.
The STEVAL-ISF003V1 board is also a development tool for designing broad inrush-
current reduction systems (EV chargers, telecom power supply, etc.). For this purpose,
connectors are available for an external power factor corrector, an intelligent power module
(IPM), or for an external microcontroller (see Section 4.5: "Possible board variations").
1.2 STEVAL-ISF003V1 functional blocks
Figure 2: STEVAL-ISF003V1 functional block diagram
See Section 5: "Schematic diagrams" for detailed schematics.

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The principal sections of the STEVAL-ISF003V1 board are:
1. T1 and T2 silicon-controlled rectifiers (SCRs) in the mixed rectifier bridge.
2. The MCU, which drives SCRs through opto-transistors (see APPENDIX 6) and can
also activate any supply or motor inverter referenced to the DC bus ground (GND_DC)
in a final application.
3. The flyback power converter providing the sources in the table below.
Table 1: Power sources from flyback converter
Source
Output
Ground
Destination
Maximum output
current
VCC_AC
5 V
GND_AC is
connected to the
HVDC bus
control SCRs (T1 and T2)
200 mA
5V_DC
+5 V
referenced to the
DC bus Ground
(GND_DC)
MCU and control circuits
90 mA
15V_DC
+15 V
referenced to the
DC bus Ground
(GND_DC)
can supply an IPM to control a
three-phase motor in a final
application
500 mA (together
with 5V_DC
consumption)
VCC_INS
+5 V
insulated output
for components which must be
insulated from the mains voltage,
(e.g., sensors). Not used on the
demoboard
90 mA
For further information regarding the SMPS outputs, please refer to Section 6: "STEVAL-
ISF003V1 power supplies and typical consumption".
1.3 Target applications
Target applications include all those using a diode-bridge to rectify the AC line voltage,
where NTC or PTC resistor removal and loss reduction in standby are desirable, such as:
EV chargers.
Telecom power supplies.
1.4 Main part numbers
The references of the main part-numbers used in this demoboard are:
Inrush-current-limiter SCRs: TN5050H-12WY
Rectifier diodes: STBR6012WY
Microcontroller unit (MCU): STM8S003F3
Flyback IC: VIPER26LD
1.5 Operating range
The STEVAL-ISF003V1 board is designed to operate inside following operating ranges:
RMS line voltage range:85 to 264 VRMS
Line voltage frequency range: 45 to 65 Hz
Ambient temperature range is: 0 to 60 °C (heatsink fans keep junction temperature of
bridge components below Tjmax)
Maximum input current: 32 ARMS (7.4 kW input power for operation on 230 VRMS and
3.6 kW input power on 120 VRMS).

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Allowed DC output capacitor (or DC bus capacitor): up to 2 mF. This value is the
equivalent of all capacitors in parallel at the bridge output, like C3 and CPFC at the PFC
in the figure below. If an interleaved PFC is used, all the output capacitors of each
PFC must be added.
Figure 3: Connection of a PFC at the HVDC output
1.6 Performance characteristics
Efficiency at 230 V 50 Hz 3.3 kW (with output DC resistive load @ COUT = 1mF) >
98%
Efficiency at 120 V 60 Hz 3.3 kW (with output DC resistive load @ COUT = 1mF) > 98
%
Standby losses < 300 mW (see Section 3.7: "Standby consumption")
Compliance with IEC 61000-3-3 (with MAX_INRUSH CURRENT potentiometer set to
default position, see Section 7: "Inrush-current limitation")
Compliance with EN55014 (CIPSPR 22 method B, see Section 11: "EN55014 test
results")
IEC 61000-4-4: 2 kV criteria A, SCR1 and SCR2 withstands a level of 5 kV without
triggering. This avoids undesired triggering and uncontrolled inrush current in case of
EMI noise.
IEC 61000-4-5: 4 kV
IEC61000-4-11: criteria A for dips down to 100% of the line voltage during 1 cycle;
criteria B for interrupts up to 300 cycles or more (see Section 8: "Mains voltage dips
and interruptions").
The figure below shows an example of the progressive DC capacitor charge which is
ensured by SCR1 and SCR2. The test is performed at start-up when the STEVAL-
ISF003V1 board is connected to a 230 V, 50 Hz grid (VAC), while the output DC capacitor is

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completely uncharged (its initial voltage is null). The output DC capacitor connected to the
demonstration board is 1 mF.
The output capacitor is charged over 900 ms while the input RMS current (2.8 A) remains
far below the 16.1 A (IAC). The input RMS current easily complies with the IEC 61000-3-3
standard.
Figure 4: Inrush current at STEVAL-ISF003V1 start-up on 230 V line (1 mF output DC
capacitor)
1.7 Standby consumption
Mixed SCR/Diode rectifier bridges prevent undesirable standby losses through full bridge
disconnection by simply turning off the SCRs; this would otherwise require a front-end
relay, like S2 in the figure below, to achieve.
Figure 5: Solution using relays to limit the inrush current and standby losses
To appreciate the benefits of bridge disconnection, we measured the typical losses of the
STEVAL-ISF003V1 board in standby mode for the following cases:

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1. STEVAL-ISF003V1 board (without modifications) with SCRs in the OFF state (SW2
HVDC switch in OFF position) and the J1 bypass mode jumper is unplugged (PTC not
connected).
2. Same as 1, but the following circuits used for demonstration purposes and which
consume undesired power in standby are disconnected:
HV Capacitor Discharge circuit: R5 and R6 are disconnected from the DC bus
D6 HVDC LED: D1 is disconnected from the DC bus
D14 POWER_ON LED: R44 is disconnected
3. Same as 2, but the J1 bypass jumper is plugged (PTC connected) to simulate the
losses for a conventional solution using only one PTC (EPCOS B59107J0130A020).
Table 2: "Comparison of standby losses" gives the experimental results for the above
cases with 230 and 120 V line voltages and a 2-mF HV output capacitor connected to the
demonstration board. The test results clearly show that the mixed SCR/Diode bridge
rectifier is the only solution with power consumption lower than 0.5 W, as currently required
by European directive 2005/32/EC.
The losses on this demonstration board are mainly due to:
resistors R54, R55 and R56 to discharge the HV output capacitor
resistors R7 and R9 and the current source to control HVDC LED indicating HVDC
voltage
resistors R6 and R9 to accelerate the HV output capacitor discharge time connected
to the demonstration board output
the other R24, R25 and R28 resistor divider circuit to sense the HVDC voltage
The HVDC voltage is monitored to ensure proper soft-start operation and avoid the DC
capacitor charging too long (e.g., a load is kept connected to the DC bus before start-up).
In standard circuits, such a voltage sensor is often required (e.g., to start the PFC or the
DC/DC supplies).
The losses for a 230 V rectified voltage are:
140 mW for the discharge circuit
500 mW for the HVDC LED circuit
180 mW for the acceleration circuit to discharge the HV output capacitor connected to
the demonstration board output
52 mW for the HVDC sense.
Table 2: Comparison of standby losses
case
SCR
status
PTC
status
circuits
power consumption (mW)
Power
LED
HVDC
LED
HV capacitor
discharge
circuit
VAC=230
VRMS,
CHVout=2 mF
VAC=120
VRMS,
CHVout=2 mF
1
OFF
OFF
connected
270
200
2
OFF
OFF
disconnected
200
140
3
OFF
ON
disconnected
500
200