dsPICDEM™ MCHV-3 DEVELOPMENT
BOARD USER’S GUIDE
2016 Microchip Technology Inc.
DS50002505A-page 31
Chapter 3. Hardware
This chapter describes the hardware components of the dsPICDEM™ MCHV-3
Development Board.
Topics covered include:
•
Power Factor Correction (PFC) Stage Board
•
•
3.1
POWER FACTOR CORRECTION (PFC) STAGE BOARD
This board has two main functions: the first one is to provide the required power
supplies to the Power Module Stage Board; the second function is to create the power
bus rail that will be used to energize the motor through the power module.
3.1.1
AC Supply Input
The AC supply input stage of the board consists of the following components:
• F1 – 15A/250 VAC fast acting fuse (only replace with a part of the same rating).
• C1, C2 – Film capacitors to aid in the suppression of AC supply transients, and to
also provide a low-impedance return path for any currents that flow from the
power device tabs to the heat sink and enclosure due to capacitive coupling.
• C3 – Film capacitor to aid in the suppression of AC supply transients.
• R1 – A metal oxide varistor located across the incoming supply lines to suppress
high-energy transients.
• L1 – 2.3 mH/15A choke inductor for suppressing EMI.
• C4 – Film capacitor to aid in the suppression of EMI.
• C5, C6 – Film capacitors to aid in the suppression of AC supply transients. and to
also provide a low-impedance return path for any currents that flow from the
power device tabs to the heat sink and enclosure due to capacitive coupling.
• R7 – A 1W high-voltage resistor, which acts to discharge C4.
• R6 – A resistor with a negative temperature coefficient that acts to limit the surge
of input current that would occur at initial application of power due to the dis-
charged DC bus capacitance. The initial nominal cold resistance is 1 Ohm, which
reduces once current flows and the device heats up.
• BR1 – A single-phase bridge rectifier to convert the incoming AC into DC suitable
for input to the power conditioning stage.
• K1 – Relay which comes into operation after the inrush current dies out.
• R76, R77 – These are the voltage divider resistor outputs, which are connected to
the gate input of the MOSFET.
• C25 – This is used as a charging capacitor to introduce delay before turning on
the MOSFET.
• U9 – MOSFET is used to turn on the relay, K1.
• D15 – Diode is used to avoid premature turn-on of the MOSFET.
Note:
The circuits for the hardware described in this section are shown in