According to the manufacturing of the boosting inverter used in the high power electric digital tank gun control system, the paper analyzes the principle of peak-voltage, magnetic deviation and waves surging.

Research on the flux imbalance of UPS output transformer;

Research on avoiding flux imbalance in sine wave inverter;

So flux imbalance is avoided completely.

The mechanism of magnetic bias exists in power transformerof the single-stage full bridge PFC converter;

A new automatic tuning principle and its application of arc-suppression coil with magnetic bias;

A scheme to adijust magnetic bias in bridge converter based on DSP;

Research on Dc Biased Transformers Caused by HVDC or Geomagnetic Storm;

The monipolar ground circuit operation mode of HVDC system results in the DC bias of power transformers and current transformers in AC power system.

During monopolar operation of HVDC systems with ground return, a large- scale DC enters into neutrals of transformers, which causes DC bias of transformers.

DC biasing can cause transformers noise increasing,vibration intensified,local overheating and even damaged.

The enormous ground return current caused by HVDC (high voltage direct current) system s mono-pole ground return operation mode will result in the main transformer DC biasing at the substations near the ground electrode, thus it has disadvantageous effect on AC (alternative current) system.

The mechanism of DC biasing for output transformer of SPWM switching converter was analyzed.

Influence of DC magnetic bias on excitation current of transformer;

The authors research such existing technical problems as electromagnetic environment, over-voltage and insulation coordination, DC magnetic bias, control and protection system, stability of hybrid UHVAC/DC power grid.

HVDC from Tianshengqiao power station to Guangzhou and that from Three Gorges power station to Changzhou, the DC magnetic bias of large capacity power transformers occurs under monopole operation mode with earth return.