﻿ Four Quadrant Power Supply               Instruments For Testing Your Innovations    # Four Quadrant Power Supply

A four quadrant power supply is a lab power supply that can output both positive or negative voltage. It can sink or source current regardless the voltage is positive or negative. In contrast, most laboratory power supply can only source current and cannot sink current. Conventional power supply is operating in the first quadrant as shown in Figure 1. In the first quadrant, a common power supply output voltage is positive and source current only. A 4-quadrant power supply on the other hand, it can operate in any of the quadrant and it seamlessly transition between quadrants.

## A two quadrant power supply is typically operate in quadrant 1 and 4. This type of voltage supply outputs only positive voltage, but it can source and sink current. When it sourcing current, it is in quadrant-1. When it is sinking current (voltage still positive), it is in quadrant-4. The ability to operate in sink and source current mode make them a 2-quadrant power supply. Many test and measurement applications only require two quadrants, but most available voltage supply are either one quadrant or four quadrant. A 4-quadrant voltage supply supercedes two quadrant supply.  That is, a four-quadrant supply can do the job of two-quadrant. Accel Instruments offers both 4-quadrant and 2-quadrant power supplies. Figure 1. IV Diagram of a power supply showing all four quadrants.

## To characterize the photovoltaic, the four-quadrant voltage supply is connected to the solar cell output. The 4-quadrant supply is forcing the solar cell to a fix voltage. At the same time, current into the 4-quadrant power supply is measured. Starting from 0V, the current from the cell into the supply is measured. This is the short-circuit current. Then increase the voltage (i.e. 0.2V) and measure the current again. Keep increase the voltage while measuring the current, until the current is near zero. This is the open-circuit voltage. Figure 4 shows an example of photovoltaic cell IV curve. Figure 2. Battery simulator connection using while operating in quadrant 1 and 2. Figure 3. Photovoltaic cell (solar panel) test and characterization using a four-quadrant supply. Figure 4. Photovoltaic cell current-voltage (IV) characteristic tested using Figure 3 setup.  ### Table 1. Four-Quadrant Power Supply Selection Guide Battery Simulator For Charger Testing   ### Quick Links ## The TS200 Modulated Power Supply can produce both AC and DC voltage and it is ideal for producing AC voltages for testing applications such as power supply rejection (PSRR). The TS250 Waveform Amplifier can produce high-power voltage waveforms for testing applications such as ultrasonic transducer amplifier for example. PDF Version of this App Note