DC-TO-DC CONVERTER

• US 20150103565A1
• Filed: 10/09/2014
• Published: 04/16/2015
• Est. Priority Date: 10/15/2013
• Status: Abandoned Application

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: SHIMAMORI, HIROSHI, Yoshino, Yukio
• Application Number:
  US14/510,524
• Publication Number:
  US 20150103565A1
• Time in Patent Office: Days
• US Class Current: 363/21.09
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 1/0048 Circuits or arrangements for reducing losses using snubbers H02M1/34
• CPC Class Codes: H02M 3/33573 Full-bridge at primary side of an isolation transformer
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A direct current to direct current converter includes: a transformer configured to vary a direct-current voltage applied to a first side and output the varied direct-current voltage to a second side; a switch configured to periodically switch the voltage applied to the first side of the transformer; a load-current detecting circuit configured to detect load current flowing in the second side of the transformer; and a switching-frequency switching circuit configured to switch, when a magnitude of the load current detected by the load-current detecting circuit is smaller than a predetermined threshold, a frequency for switching the switch from a first frequency to a second frequency lower than the first frequency, and to switch, when the magnitude of the load current detected by the load-current detecting circuit is larger than the predetermined threshold, the frequency for switching the switch from the second frequency to the first frequency.

Claims

1. A direct current to direct current converter comprising:

a transformer configured to vary a direct-current voltage applied to a first side and output the varied direct-current voltage to a second side;

a switch configured to periodically switch the voltage applied to the first side of the transformer;

a load-current detecting circuit configured to detect load current flowing in the second side of the transformer; and

a switching-frequency switching circuit configured to switch,

when a magnitude of the load current detected by the load-current detecting circuit is smaller than a predetermined threshold, a frequency for switching the switch from a first frequency to a second frequency lower than the first frequency, and to switch,

when the magnitude of the load current detected by the load-current detecting circuit is larger than the predetermined threshold, the frequency for switching the switch from the second frequency to the first frequency.

2. The direct current to direct current converter according to claim 1,

wherein, during the switching of the frequency for switching the switch from the first frequency to the second frequency lower than the first frequency, the switching-frequency switching circuit gradually reduces the frequency.

3. The direct current to direct current converter according to claim 2,

wherein a transition time in which the frequency for switching the switch from the first frequency to the second frequency is longer than a transition time in which the frequency for switching the switch is switched from the second frequency to the first frequency.

4. The direct current to direct current converter according to claim 1,

wherein the switch comprises a plurality of metal oxide semiconductor transistors.