Download Constant Voltage Power Supply , Constant Current Mode

CONSTANT VOLTAGE POWER SUPPLY AND CONSTANT CURRENT POWER SUPPLY
Before we go into the Constant Current Power Supply , we have to start with the Constant Voltage
Power Supply .
Most power supplies found in the market are Constant Voltage Power supply type.
1.
When a load is connected to the output of a power supply , the output VOLTAGE ( which can be fixed
VOLTAGE , or adjustable ）of the power supply remains constant at the set VOLTAGE for the given
range of CURRENT within the rated output power of the power supply.
The load may use ,say 1 AMP or 5 AMP or 10 AMP and the output VOLTAGE remains at the set or at
the adjusted value as long as the loading is within the rated power and specified voltage and current
limits of the power supply .
How much is the resulting CURRENT as shown on the METER really depends on the nature of the load
but the output always remains constant .
2.
Now a constant current power supply always gives the load the same set current over a range of
voltages .
In fact when you substitute the words VOLTAGE by CURRENT ,and CURRENT by VOLTAGE , AMP by
VOLT
in paragraph 1 then you have a full description of a constant voltage power supply.
3. CONSTANT CURRENT POWER SUPPLY can be treat as power supply running in CC mode
4. CC ( constant current ) mode / current limiting of the constant voltage power supply
Some constant voltage power supplies have adjustable current limit , that means the output current
level can be adjusted and limited to a set value .
For example you can set the current limiting value to 1.5 amp , and the power supply will go into CC
mode when the output current is more than 1.5 amp.
And the power supply will give a constant current of 1.5Amp to the load usually with a voltage lower
than the voltage at CV (constant voltage )mode before power supply enters into CC mode,
This is more of a safety measure of limiting the amount of current to the load .
5. How to set the Current Limiting Value of a constant voltage power supply
First you set your desired voltage level for your load , then you short circuit the power terminals ,
watch out for the sparks and adjust the current limiting value .
Nowadays more advanced power supply has "output open circuit current limiting setting “ such as
HSC ，NDP, SDP, ...
So there is no need to do the short circuiting and face the spark in short circuiting the output.
For example : if your load operates at around 6 V and draws up to 2A. you want to have a constant
current of 1.5A , you can set your power supply voltage to 6V and current limiting value of 1.5A .
At 6V , the load may draws under 1.5A and when the load increases the current draw to more than 1.5V
or when you increase the voltage such that the current increases to over 1.5A ,
the power supply will be in CC mode with current showing 1.5A and voltage drops back to around 6V .
6. AUTO CROSS OVER CV TO CC OR CC TO CV MODE.
There is no such selection switch of CV or CC mode with HCS or any of our power supplies.
In the above example when the power supply is in CC mode , if the load decreases the current draw
from 1.5 A to 1.4A , the power supply will automatically change to CV .
Or the power supply is in CV mode and if the load increases current draw, the power supply will cross
over to CC mode.
Similarly you can either change the voltage or current setting of the power supply for auto cross over of
CV , CC .
7. The property of the load has lot of bearing on the CV and CC mode of the power supply .
The CC mode of a constant voltage power supply is a consequence of current limiting function of the
power supply.