Microchip Technology dsPICDEM MCHV, Руководство пользователя

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dsPICDEM™ MCHV
DEVELOPMENT SYSTEM
USER’S GUIDE

2009 Microchip Technology Inc. DS70605A-page 29
Chapter 4. Hardware
This chapter describes the hardware components of the dsPICDEM™ MCHV
Development System.
Topics covered include:
• Power Factor Correction (PFC) Stage Board
• Power Module Stage
• Electrical Specifications
4.1 POWER FACTOR CORRECTION (PFC) STAGE BOARD
This board has two main functions; the first one is to provide the required power sup-
plies to the power module board stage. The second function is to create the power bus
rail that will be used to energize the motor through the power module.
4.1.1 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 flows 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.
Note: The circuits for the hardware described in this section are shown in
Appendix A. “Board Layout and Schematics” .