top of page

Constant Voltage, Constant Current, and now Constant Power!

Download PDF


The SE Programmable Power Platforms (SE.10.36.00 series) have an intelligent hybrid architecture that combines the benefits of both linear and switching power supplies. It is more efficient and compact than a purely linear power supply, but still maintains the high level of regulation and low level of noise that is characteristic of linear power supplies. The SE Power Platform is fully programmable, allowing the user to source and measure electrical quantities such as voltage, current, power, and charge via the SE Companion desktop application. In this application note, we discuss the three major modes of operation.

 

Constant Voltage Mode:

Constant Voltage (CV) is the most common mode of operation in power supplies. In this mode, the power supply outputs a fixed voltage across its entire load range. Constant voltage can be achieved by directly controlling the output voltage or modulating the current to achieve a constant voltage across the load. The SE platform directly controls the voltage across the load, giving very small noise levels (< 6 mV Vpp and < 1 mV rms). Equipped with a novel range-independent source and measurement resolution of 1 mV, the SE platform can source voltages from 0 V to 36.000 V. Featured with a four-wire measurement modality and digital control system, the device compensates for any voltage drop across the wires connected to the load to ensure stable and precise voltage delivery to the load with load regulation of less than 0.2 mV. This combination of features makes the SE platform ideal for applications requiring accurate and stable voltage delivery.


Applications: Constant voltage mode of operation, also known as potentiostatic mode in electrochemistry, has numerous applications ranging from microelectronics to biomedicine. Constant voltage mode can be used for charging batteries. However, due to the large current draw at the starting interval, there can be significant heat dissipation which can degrade the battery life and even cause catastrophic failure. For resistive and capacitive systems, the voltage (i.e., V2) controls the power consumption and energy stored in the system, respectively.

 

Constant Current Mode:

In the Constant Current (CC) operating mode the power supply maintains a constant output current over changing load conditions. This mode can be achieved by directly controlling the current or modulating the voltage to achieve a constant current across the load. The SE platform directly controls the current across the load, giving very small noise levels and good current regulation. The SE platform can source currents from 0 A to 16 A. Featured with a digital control system, the device can provide load regulation of less than 0.2 mA. The four-wire measurement modality allows the user to measure the resistance of a wide range of loads precisely.


Applications: Constant current mode of operation, also known as galvanostatic mode in electrochemistry, has numerous applications ranging from semiconductor devices to certain actuators. The constant current mode can be used for charging batteries. However, there can be a risk of overcharging the battery in the last stages of charging. For resistive and inductive systems, the current (i.e., I2) controls the power consumption and energy stored in the system, respectively.

 

Constant Power Mode:

In the Constant Power (CP) operating mode, the power supply maintains a constant output power over changing load conditions. This mode can be achieved by directly controlling the voltage (or modulating the current) or current (or modulating the voltage) to achieve a constant power across the load. Power control can be performed in the analog or digital domain. The SE platform uses a novel hybrid approach (with no PWM) that allows a conversion time of less than 1 µs. The SE platform can source power from 0 W to 576 W with 1 mW source resolution and 1 µW measure resolution. Featured with a digital control system, the device can provide load regulation of less than 0.2 mW. The four-wire measurement modality compensates for any voltage drop across the wires, ensuring stable and precise power delivery to the load.


Applications: Constant power mode of operation has numerous applications ranging from precision resistive heating to ion and electron thermionic emission devices. Moreover, this mode allows for safe battery charging by limiting the charging power without the need for complex control mechanisms.

62 views
bottom of page