Switching power supply device, switching power supply control method, and electronic apparatus

• US 9,882,498 B2
• Filed: 05/22/2014
• Issued: 01/30/2018
• Est. Priority Date: 05/29/2013
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Watanabe, Hiroyuki
• Primary Examiner(s): Benitez, Gustavo Rosario
• Application Number:
  US14/284,843
• Publication Number:
  US 20140355315A1
• Time in Patent Office: 1,349 Days
• CPC Class Codes: H02M 1/4241 using a resonant converter
• CPC Class Codes: H02M 3/33546 with automatic control of the output voltage or current H02M3/33561 takes precedence
• CPC Class Codes: H02M 7/4815 Resonant converters H02M7/4811 and H02M7/4826 take precedence
• CPC Class Codes: H02M 7/523 with LC-resonance circuit in the main circuit
• 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 switching power supply device includes a switching element to which a DC input is supplied, a frequency control circuit which controls a switching frequency of the switching element, a frequency detection circuit which detects the switching frequency of the switching element, and a duty ratio control circuit which controls a switching duty ratio based on the frequency detected by the frequency detection circuit. The duty ratio control circuit controls the switching duty ratio such that the switching frequency becomes an approximately maximum frequency.

Claims

1. A switching power supply device comprising:

a switching element to which a direct current (DC) input is supplied;

a frequency control circuit which controls a switching frequency of the switching element;

a frequency detection circuit which detects the switching frequency of the switching element; and

a duty ratio control circuit which controls a switching duty ratio based on the switching frequency detected by the frequency detection circuit,

wherein the duty ratio control circuit controls the switching duty ratio such that the switching frequency becomes an approximately maximum frequency, and

wherein the duty ratio control circuit operates using the switching duty ratio in an area where a slope of a change of the switching frequency with respect to a change of the switching duty ratio becomes positive.

2. The switching power supply device according to claim 1, further comprising:

a transformer;

a resonance circuit; and

a rectification circuit,

wherein the switching element is configured by a first switching element and a second switching element which are connected in series and alternately turned on by the switching frequency,

wherein output currents of the first and second switching elements are supplied to the transformer,

wherein the resonance circuit is connected to a primary side of the transformer, and the rectification circuit is connected to a secondary side of the transformer, and

wherein an output voltage is stabilized by a frequency of a switching signal which is controlled by a feedback signal.

3. The switching power supply device according to claim 2, wherein a time of changing the switching duty ratio is set so as to be longer than a response time which is determined from a band of the feedback signal.

4. The switching power supply device according to claim 1, wherein the duty ratio control circuit performs a duty ratio control operation.

13. The switching power supply device according to claim 1, wherein the switching frequency relates to a fixed value of an ON period of the switching element.

5. A switching power supply control method of a switching power supply device including a switching element to which a direct current (DC) input is supplied, a frequency control circuit which controls a switching frequency of the switching element, a frequency detection circuit which detects the switching frequency of the switching element, and a duty ratio control circuit which controls a switching duty ratio based on the switching frequency detected by the frequency detection circuit, the method comprising:

detecting the switching frequency of the switching element; and

controlling the switching duty ratio based on the switching frequency detected by the frequency detection circuit such that the switching frequency becomes an approximately maximum frequency,

wherein the duty ratio control circuit operates using the switching duty ratio in an area where a slope of a change of the switching frequency with respect to a change of the switching duty ratio becomes positive.

7. The switching power supply control method according to claim 5, further including:

alternately turning on first and second switching elements of the switching element according to the switching frequency;

providing output currents of the first and second switching elements to a transformer; and

stabilizing an output voltage in accordance with a frequency of a switching signal controlled by a feedback signal.

8. The switching power supply control method according to claim 5, wherein a time of changing the switching duty ratio is set so as to be longer than a response time which is determined from a band of a feedback signal.

9. The switching power supply control method according to claim 5, wherein the duty ratio control circuit performs a duty ratio control operation.

6. An electronic apparatus comprising:

a switching power supply device, wherein the switching power supply device includes a switching element to which a direct current (DC) input is supplied;

a frequency control circuit which controls a switching frequency of the switching element;

a frequency detection circuit which detects the switching frequency of the switching element; and

a duty ratio control circuit which controls a switching duty ratio based on the switching frequency detected by the frequency detection circuit,

wherein the duty ratio control circuit controls the switching duty ratio such that the switching frequency becomes an approximately maximum frequency, and

wherein the duty ratio control circuit operates using the switching duty ratio in an area where a slope of a change of the switching frequency with respect to a change of the switching duty ratio becomes positive.

10. The electronic apparatus according to claim 6, further comprising:

a transformer;

a resonance circuit; and

a rectification circuit,

wherein the switching element is configured by a first switching element and a second switching element which are connected in series and alternately turned on by the switching frequency,

wherein output currents of the first and second switching elements are supplied to the transformer,

wherein the resonance circuit is connected to a primary side of the transformer, and the rectification circuit is connected to a secondary side of the transformer, and

wherein an output voltage is stabilized by a frequency of a switching signal which is controlled by a feedback signal.

11. The electronic apparatus according to claim 6, wherein a time of changing the switching duty ratio is set so as to be longer than a response time which is determined from a band of a feedback signal.

12. The electronic apparatus according to claim 6, wherein the duty ratio control circuit performs a duty ratio control operation.