The schematic in figur is the circuit of 600W UPS. Stay powered and radio during a power failure. Output frequency – 50 Hz, Power Consumption 600 Watts, the shape of the output signal – sinusoidal, the efficiency – 98%. The device contains an auto power off at the mains, followed by automatic switch-off with the appearance of tension.
At the transistor T1 assembled oscillator stabilized resonator 128 kHz. On the U1 and U2 performed for the frequency divider 256. At the exit 2/U2 received pulse sequence frequency of 500 Hz. U3 divider forms two pulse sequences at 50 Hz with a phase shift of 180 º to control the powerful switching transistors T4 and T5. To eliminate the cross-currents in the moment of switching off one key and another in the scheme provided for Dead time 10% of the length of the period.
At the transistor T2 collected a protection against deep discharge battery. Adjustment of this stage is carried out by choosing the resistor R5, so that when the voltage drops at the battery to 10 V transistor T2 and locked through R7 and D2 on the output level is set 15/U3 logical unit, which will lead to the blocking of U3. Integrating capacitance C9 prevents lock in case of a short low voltage battery.
The transistor T3 is made protection from overcharging the battery if the battery voltage exceeds 15 V, the U3 through resistor R10 will be blocked and D3.
In the T6 and T7 anti-lock assembly assembled U3, running continuously. C11 is charged to the voltage in the absence of pulses, with the logical unit is fed to the conclusion 15/U3 through D7. In normal operation, the inverter output 1/U3 every 20 ms there is a logical unit, which opens through T7 and R12 discharges C11, not allowing you to disable U3.
In the automatic switching of the inverter unit includes optocoupler AOT128, the LED which is powered by voltages R19, diode bridge D21, C13, R16. Instead, optocouplers, defined in the diagram, you can use AOT127B, but instead of R15, 100 k resistor to install 820 kW. Relay P1 – REN-34 or similar on the voltage of 27 V. The switch S1 blocks the transmitter. Capacitor C14 approximates the shape of the output voltage to a sinusoidal and is selected by the minimum current consumption from the battery at idle.
Transformer capacity of 500-600 watts, with ratio 20.
When you connect to the battery terminals to prevent the breakdown of transistors T4 and T5 to block the work of the converter switching toggle switch S1.