This reference design discusses a 750 VA single phase online uninterruptible power supply (UPS) intended to protect power-sensitive systems like computers and workstations. Its output waveform is a true sine wave with less than 5 per cent THD. The design is based on microcontroller MC9S12E128 and includes a dc/dc step-up converter, a battery charger and an output inverter. The dc/dc converter and the output inverter are fully digitally controlled. The design utilizes indirect PFC control meaning that the voltage (outer) control loop is performed digitally by the microcontroller. The use of the indirect control approach reduces instruction loading of the MCU. The PFC running in average current mode makes the system suitable for medium and higher power applications. Click here to know more about the reference design
1 kVA Offline UPS with Low Switch over Time:
Here is a reference design for a 1kVA Offline UPS using a Switch Mode Power Supply (SMPS) dsPIC Digital Signal Controller (DSC). This UPS works in two modes: Standby mode and UPS mode. Until a failure occurs on the AC line, the system remains in standby mode. In this mode, the system acts as a rectifier charging the battery to its full capacity. A Flyback switched mode charger charges the battery with constant current. In case of power failure, the system switches to UPS mode with the help of a DPDT relay. The push-pull converter steps up the battery voltage to 380 VDC. A full-bridge inverter converts the high DC voltage and filters it with an LC filter to deliver a pure sine wave 220/110 VAC output to the load. This power switchover sequence is made in less than 10ms. Click here to see detailed reference design.
5KVA Single-Phase On-Line UPS Reference Design with XC164CM:
Here is a 5KVA single-phase UPS reference design that offers an integrated UPS solution with 16-bit microcontroller XC164CM. The MCU performs all control functions like charger module control, PWM signals generation, output voltage feedback control, system faults and errors and modules synchronisation. A monitoring board based on Infineon 8-bit microcontrollers XC866 handles LCD and keyboard operations. A full-bridge inverter is utilised whose output voltage is boosted by an isolating transformer and then filtered by the circuit consisting of inductor and capacitors. If case of input mains failure, the battery module is switched to offer power to the inverter to provide uninterrupted power. To know more, click here.