CPWR-AN26, Rev A, 08-2018
Copyright © 2018 Cree, Inc. All rights reserved.
The information in this document is subject to change without notice.
Cree and Zero Recovery are registered trademarks, and the Cree logo and C3M are trademarks, of Cree, Inc
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Open MCB1 disconnecting the DC power supply from the input.
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The DC link capacitors remain charged for at least 30 minutes after the circuit is turned
OFF, although you may decrease the time that it takes for the board to be fully
discharged by adding a discharge circuit to the DC link. Allow the unit to fully
discharge before turning OFF any of the digital logic/DSP power supplies, and do not
touch the unit until it has been fully discharged. Please check the DC link voltage with
a multimeter to ensure that the board has fully discharged and is therefore safe to
handle.
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Switch OFF +15V and +24V power supplies first.
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Switch OFF +7V power supply. The +7V must be turned OFF last since it serves as the
DSP supply voltage. Failure to turn OFF the +7V last may cause damage to the circuit.
Please take the following steps in order when starting the unit in DC/AC OFF grid mode with
resistive load:
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If the board is being tested for the first time, follow the procedures described at the
beginning of Section 7.
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The board should be connected as shown in Figure 8.
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Keep MCB1 (DC supply) in open position
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Keep output isolated from the load by keeping MCB2 in the open position.
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Put ON/OFF switch (sw2) in OFF position
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Put mode switch (sw1) in DC/AC position.
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Connect +7V supply to J7 connector (positive (+) to pin 1 and negative (-) to pin 2).
Confirm that the current drawn from the 7V supply is similar to the current value shown
in Table 5.
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Switch ON +15V, +15V_1, and the power supplies and confirm that the current drawn
is same as shown in Table 5.
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Keep the Resistive load in No load position and then turn ON MCB2.
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Turn ON the 24V supply and a cooling fan that should be attached to the supply.
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Put MCB1 in ON position and slowly increase the DC supply voltage to the required value
(320 VDC
–
450 VDC). DC supply voltage should be increased gradually because there is
no inrush current limiter at this end.
•
Put sw2 in ON position and check the output voltage.
•
Increase the load up to 3.3kW in steps of 1kW maximum.
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Check for the overall efficiency of the DC/AC stage and the THD.