4 Using the Regenerative Power System
Current Sinking Operation
Current Sinking
Regenerative Operation
Current Sinking
Current sinking, also referred to as downprogramming, is the ability to pull current into the positive
terminal of the DC power supply. For example, the power supply pulls or sinks current into the positive
terminal whenever a lower output voltage is programmed. This is necessary because stored energy
from the power supply's output capacitor and external capacitance from the load including the wiring
must be discharged to lower the voltage at the output terminals.
The ability to rapidly transition from a higher to a lower constant voltage level greatly improves the
power supply's output response time. This is the most commonly used application of the regenerative
function of the RPS, which is automatic and completely transparent to the user.
The DC power supply can continuously sink up to 100% of its rated current for an indefinite time. This
two-quadrant
sourcing and sinking capability of the DC power supply allows for seamless transitions
between sourcing and sinking current without changing the power supply's output characteristics or
introducing any disruptive behavior. The following controls are provided to fully utilize the two-
quadrant output capability of the supply.
Current Limit control in voltage priority mode
When operating in voltage priority mode, you can program a negative and positive
current
limit. This
will limit any current overshoots that may occur during rapid up- or down-programming.
Current setting control in current priority mode
When operating in current priority mode, you can program the output current to seamlessly cross the
zero point when transitioning from positive to negative or negative to positive. Additionally, when
operating in the negative current quadrant, you can program a negative
current setting
that will hold
the sink current at the specified value. This is useful, for example, for discharging a battery at a
constant current rate.
If your application requires precise control of the source and sink currents, current
slew controls
are
available to specify a current slew rate when sourcing and sinking current.
Regenerative Operation
Regenerative operation is automatic and requires no programming on the part of the user. Whenever
the unit is sinking current, either by rapidly downprogramming the output, or by discharging an energy
source such as a battery, the unit will direct the excess power back into the AC mains. Refer to
AC
Mains Considerations
for additional information.
Keysight RP7900 Series Operating and Service Guide
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