BRIDGE VOLTAGE INVERTER WITH TRANSFORMER PROTECTION AGAINST UNILATERAL SATURATION Russian patent published in 2009 - IPC H02M1/40 

FIELD: electricity.

SUBSTANCE: suggestion consists in bridge inverter - constant voltage to alternating voltage converter with stabilisation of output voltage effective value with bridge switch, with transformer protection against saturation. There are facilities for measuring induced in windings voltage of the first and the second half-period. When the first or the second half-period is formed in the primary winding at the same time in the measuring winding current voltage is determined which is proportional to EMF of transformer core excitation. To measure and form voltage of the first half-period there is facility for current voltage effective value calculation, facility for its comparison with preset value of reference voltage source and for control of the first half-period shaping termination when equality is reached. Also there are facilities for calculation of average voltage in the first half-period and for result storing. To measure and generate voltage of the second half-period there is facility for average voltage calculation and facility for its comparison with stored average voltage obtained in the first half-period and control of the second half-period shaping termination when equality is reached. Additionally to eliminate magnetic core remanent magnetisation, switch is connected in parallel to the primary winding to short-circuit the winding in timeouts between end of one half-period shaping and start of the second half-period. To prevent through currents flowing over switches, switch closing to short-circuit the winding is performed via circuit with t1 time-delay relative to the moment of each half-period completion, and triggering the start of each half-period shaping is performed via circuit with time-delay for (t2+13) pulses coming from the first output of clock generator. Therefore range of definition in integration in formulas for effective and average voltages has been changed. In integration for each half-period, range of definition is limited to T/2-(t1+t2) instead of standard value of 172. In this case following parameters are taken into consideration: minimum permissible time for switch closed state; pulse-decay time in the bridge switch and above mentioned switch. Owning to equality of voltage-time areas of the first and the second half-periods and magnetic flows in magnetic core, technical result is achieved.

EFFECT: prevention of transformer unilateral saturation, improvement of protection against remanent magnetisation of output transformer magnetic core, mass-dimensional parameters improvement.

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