Diamond Electric Mfg. Co., Ltd.

Diamond&zebra Electric Mfg.co., Ltd.

Shogo Nakahara

Masao Watanabe

Hiroyoshi Nakayama

A DC-DC converter has a configuration in which a first full-bridge circuit and a second full-bridge circuit are connected via a transformer and an inductor. A control circuit performs soft switching of each switching element in the first full-bridge circuit and the second full-bridge circuit. An inductor current flowing through an equivalent inductor at a time of switching of turning on or off each switching element is greater than or equal to a threshold current, the equivalent inductor being equivalent to the transformer and the inductor. The control circuit outputs predetermined power by changing a voltage output period of the first full-bridge circuit and a voltage output period of the second full-bridge circuit while fixing the switching frequency and keeping a polarity inversion period at a value greater than or equal to a fixed value, the polarity inversion period being a period in which the output of the second full-bridge circuit and the output of the first full-bridge circuit have reverse polarities. This enables performing ZVS operations by simple control and reducing switching losses.

DC-DC converter including first and second full-bridge circuits for performing soft switching and reducing switching losses

A DC-DC converter has a configuration in which a first full-bridge circuit and a second full-bridge circuit are connected via a transformer and an inductor. A control circuit controls soft switching of each switching element in the first full-bridge circuit and the second full-bridge circuit. An inductor current flowing through an equivalent inductor at a time of switching of turning on or off each switching element is greater than or equal to a threshold current, the equivalent inductor being equivalent to the transformer and the inductor. The control circuit outputs predetermined power by changing a voltage output period of the first full-bridge circuit and a voltage output period of the second full-bridge circuit while fixing the switching frequency and keeping constant a polarity inversion period in which the output of the second full-bridge circuit and the output of the first full-bridge circuit have reverse polarities. This enables performing ZVS operations by simple control and reducing switching losses.

DC-DC converter

The DC-DC converter has a configuration in which a first full-bridge circuit and a second full-bridge circuit are connected via a transformer. A control circuit controls soft switching of each switching element. An inductor current flowing through the transformer or an equivalent inductor equivalent to the transformer at a time of switching of turning on or off each switching element is greater than or equal to a threshold current. When the first full-bridge circuit and the second full-bridge circuit have different output voltages Vand V, the control circuit causes the inductor current at start times tand tof a polarity inversion period to approach the inductor current at end times tand t, the polarity inversion period being a period in which Vand Vhave reverse polarities. This suppresses an increase in loss resulting from a flow of large current and enables ZVS control.

A DC-DC converter has a configuration in which a first full-bridge circuit and a second full-bridge circuit are connected via a transformer and an inductor. A control circuit switches between first control for changing the phases of switching elements in the first bridge circuit and switching elements in the second bridge circuit and second control for changing the switching frequencies (drive angular frequencies) of the switching elements, in accordance with target power, so that an inductor current flowing during a dead time of the switching elements becomes larger than or equal to a threshold current. The inductor current in the first control is larger than the inductor current in the second control.

Converter with soft switching function

A DC-DC converter has a configuration in which a first full-bridge circuit and a second full-bridge circuit are connected via a transformer and an inductor. A control circuit alternately turns on and off switching elements. At a dead timing when the switching elements are switched, an inductor current flowing through an equivalent inductor that is equivalent to the transformer and the inductor is larger than or equal to a threshold current. The threshold current is set so that the energy stored in the equivalent inductor becomes greater than or equal to the total energy stored in capacitors that are respectively connected in parallel with the switching elements.

A DC-DC converter has a configuration in which a first full-bridge circuit and a second full-bridge circuit are connected via a transformer and an inductor. A control circuit causes output power to follow target power by changing switching frequencies (angular frequencies) of switching elements so that that an inductor current flowing during a dead time of the switching elements becomes larger than or equal to a threshold current.

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Osaka, Japan

Shogo Nakahara