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This is the Daisy-chain transformer structure for current-balancing multiple LED strings.
This experimental prototype mainly consists of three parts:
LED driver,
MCU development board
and LED panel.
In LED driver, this row is the daisy-chain transformers,
and this row is the isolation transformers.
In LED panel, there are 7 strings in parallel,
and each string has three LEDs connected in series.
The blue switches are used to simulate the LED operating state.
This state of switch represents the LED in the normal operation.
And this state represents the LED in short circuit,
and this sate represents the LED in open circuit.
In oscilloscope, Channels 1, 2, 3 and 4 are used to test the currents of strings 1, 3, 5 and 7 respectively.
Now, let's turn on the power and show the performance of the system.
At first, all the LEDs are working in the normal operation,
it can be seen that the currents flowing through every string are very close.
Next, if this LED is in open circuit, we can see it does not affect the performance of current-balancing.
If this LED is in short circuit, we can see it also does not affect the performance of current-balancing.
If the whole string fails, we can see it also does not affect the performance of current-balancing in the other LED strings.
At last, if there is only one LED is in operating and other LEDs fail,
from this waveforms, we can see that the current flowing through this LED still maintain the same current level,
and current flowing through other LED strings is zero.