Switching power supply unit

A switching power supply and switching technology, which is applied in the direction of output power conversion devices, electrical components, and adjustment of electrical variables, can solve problems such as abnormal loss, exceeding withstand voltage, and impact, and achieve the continuous effect of preventing self-excited oscillation

CN105406715AActive Publication Date: 2016-03-16TDK CORPARATION
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2016-03-16

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Abstract

The invention discloses a switching power supply unit which includes a rectifying unit with a synchronous rectifying mode. The rectifying circuit is provided with a rectifying switch connected in series with a secondary coil of a main transformer and conducted synchronously with a conduction period of a main switch; and a commutation switch connected in parallel with the secondary coil and conducted synchronously with the conduction period of the main switch. The switching power supply unit is provided with an auxiliary switching circuit. The auxiliary switching circuit detects the generated self-oscillation when voltage flows across an output end and the main switch stops switching, and enables the commutation switch to be turned off to prevent continuous self-oscillation. The switching power supply unit can prevent continuous self-oscillation generated when the main switch is turned off.
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Description

technical field

[0001] The present invention relates to a switching power supply device including a DC-DC converter that can be used in various electronic devices, and the switching power supply device includes a synchronous rectification element including a rectification switching element and a commutation switching element. Background technique

[0002] In a switching power supply with low output voltage and high current, a synchronous rectification circuit in which the rectification element is replaced with a MOS-FET from a diode can reduce the conduction loss of the rectification part, which is advantageous in terms of efficiency and component heat generation. During the synchronous rectification operation of a synchronous rectification circuit having a rectification switching element (i.e. rectification side MOS-FET) and a commutation switching element (i.e. commutation side MOS-FET), the ON of the rectification side MOS-FET and the primary side main switch The drive si...

Examples

Embodiment Construction

[0044] Hereinafter, modes for implementing the present invention will be described in detail with reference to the drawings.

[0045] Figure 4-8 It is a figure which shows the embodiment of the switching power supply device of this invention.

[0046] First, use Figure 4 The circuit configuration of the switching power supply device according to this embodiment will be described. Figure 4 In the switching power supply device, there are: a main transformer T1, which has a primary side and a secondary side insulation, a primary side main coil Np, a secondary side main coil Ns1, and an independently set auxiliary coil Ns2; a main switch Q1, which The voltage gap is connected in series with the primary-side main coil Np; the control circuit generates / outputs the driving pulse for ON / OFF driving the main switch Q1; A synchronous rectification circuit, in which the switch Q3 for rectification is connected in series with the main coil Ns1 on the secondary side, and is driven by...