Getting started
UM2027
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DocID029048 Rev 1
if the EMI filter capacitors (C3, C4, C44 to C47) values are increased, the values
of R9, R11, R14 and R16 may be decreased so the capacitors can still discharge
to below a safe voltage level (120 V for a DC voltage) in less than one or two
seconds. Indeed the EMI filter capacitors voltage is applied to the power plug
when the board is unplugged, so power terminals with accessible live parts
represent an electric shock hazard.
2.5.3
Power factor circuit connection
A PFC can be connected on the HVDC bus through the HVDC and GND_DC connections
(J12 header). To ensure the correct operation of this PFC circuit, capacitors C1 and C9
must be unsoldered. C3 (no capacitor is soldered here by default) may be used to add a
630 V DC film capacitor.
As the T_ICL Triac is controlled by a DC gate current when the HVDC voltage has reached
its steady-state value, either a discontinuous mode or a continuous mode PFC can be
used.
For correct operation of the STEVAL-IHT008V1 front-end circuit with a PFC, the PFC must
be activated after the "PFC_START" signal has been set to a 5 V high level. This signal is
referenced to the GND_DC terminal. It is available through the J20 header.
the PFC DC storage capacitor (ref. CPFC in
Figure 3: "Connection of a PFC at
the HVDC output"
) has to within the value range defined in
Section 1.5:
"Operating range and performances"
.
2.5.4
Motor Inverter connection
An inverter or any other DC-DC power converter can be added after the PFC or directly
behind the HVDC bus output.
A 15 V positive output referenced to the DC Bus Ground (GND_DC) is available through
header J10 to supply an IPM module if needed. Ensure that the maximum current which is
sunk from this supply is well below the limit given in
Figure 12: "Typical output
characteristics of the 5 V and 15 V positive supplies (5V_DC / 15V_DC)"
.
2.5.5
Control with an external microcontroller
It is possible to control the STEVAL-IHT008V1 front-end circuit with an external MCU,
instead of using the embedded STM8S103K3. This allows the end-user to directly check
the compliance of his or her own firmware with this kind of circuit.
For this purpose, all control signals required to drive the different AC switches are available
on the J16 header. EC1 to EC5 are the external control signals of AC switches T1 to T5;
T_ICL is the connection to externally drive the T_ICL Triac. The GND_DC and ZVS signals
are also available on this header to synchronize the control signals of the external MCU.
For correct operation with external signals, jumpers J1 to J6 (refer to the
"INT/EXT_CONTROL" label
Figure 23: "STEVAL-IHT008V1 silk-screen (Top side)"
) must
be removed. The removal of these jumpers indeed allows the disconnection of the opto-
transistor input LEDs from the U9 microcontroller outputs (
Figure 8: "STEVAL-IHT008V1
power side and insulated control schematic"
).
