MC1H3 Datasheet, PDF (23/60 Pages) Microchip Technology – High Voltage Power Module Users Guide

Set Up and Operation
FIGURE 1-6:
30
25
20
15
10
5
0
0
DC BUS VOLTAGE RIPPLE
200 400 600 800 1000
Output Power (Watts)
PFC Active 208V AC
50 Hz Input 350V Bus
PFC Choke in Circuit
208V AC 50Hz
PFC Choke in Circuit
110V AC 60Hz
Note that if operating without the PFC inductor in circuit that the DC bus voltage ripple
is similar in magnitude to that shown above but the average DC bus voltage is higher
for the same power.
1.3.5 Brake Chopper Output Current Limits
The brake chopper switch and diode are capable of providing the full rated output of
4A within the entire operating range (voltage, temperature and at up to 16 kHz
modulation frequency) of the system. The brake chopper diode has been oversized
from that usually required due to the inductance of an external braking resistor and
cables so that the brake chopper is more general purpose.
Note:
The user should note that the over current trip levels are set above the peak
of the rated output. This is to prevent nuisance trips. The user should avoid
operating the system beyond the peak output of 4A continuously. Operation
of the system just beneath the over-current trip of 4.9A may affect long-term
reliability of the brake chopper switch and should be avoided. The value of
the brake chopper resistor should be chosen to ensure no more than 4A
can flow, even at the peak DC bus voltage.
1.4 DETAILED DESCRIPTION OF OPERATION
1.4.1 AC Supply Input Stage (Appendix A, Sheet 1)
The AC supply input stage of the board consists of the following components:
• F1 – 1.25" x 0.25" 5A 250 VAC high rupture fuse – Note: only replace with part of
the same rating.
• C8 – X2 class film capacitor to aid in the suppression of AC supply transients.
• R11 – A 1W high voltage resistor which acts to discharge C8.
• C9, C10 – Y class 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.
• BR1 – A single-phase bridge rectifier to convert the incoming AC into DC suitable
for input to the power conditioning stage.
• V1 – A metal oxide varistor located across the incoming supply lines to suppress
high energy transients.
© 2003 Microchip Technology Inc.
DS70096A-page 17