Block diagram

The block diagram for the CU81xx UPS is described in this chapter. The input voltage Uin typically comes from a single-phase (230 V) or three-phase (400 V) AC power supply, the secondary side of which provides the 24 V DC operating voltage for the UPS. The charging electronics takes the energy for charging the energy carrier, i.e. the batteries or capacitors, from this input voltage. The charging electronics ensures that all parameters of the energy carrier (e.g. maximum charge or discharge currents, temperatures, minimum energy) remain within the permitted limits.

If the input voltage is at least 24 V - 15 % (20.2 V), the UPS, which is connected between the AC power supply and the load to be supported, always supplies at least 24 V at the output due to a step-up converter. If the input voltage drops below this value, operation is switched to UPS mode and the output is supplied by the energy storage device (UPS mode). The UPS then continues to supply exactly 24 V. In the case of an input voltage from 24 V to 24 V + 20 % (28.8 V), this is present directly at the output due to the bypass circuit. If the input voltage exceeds the threshold of 28.8 V, a transition to UPS mode takes place in order to protect the end devices. At the same time, an overvoltage warning is output. Therefore, less than 24 V and more than 28.8 V can never be present at the UPS output.

The complete control of the UPS is handled by the central UPS controller, which orchestrates the interaction of all other microcontrollers (UPS-OCT communication, charge controller).