JPS6339462A - Snubber circuit for switching power supplly - Google Patents

Abstract

PURPOSE:To prevent the damage of a transistor due to the saturation of a transformer by adding a simple charging circuit to a snubber circuit on blocking oscillation, etc. CONSTITUTION:With a switching power supply, voltage fluctuation applied to load is detected, a PWM drive section is driven by a control section, and a switching transistor (hereinafter called Tr) 6 is controlled, thus applying fixed voltage to load. A snubber circuit consisting of a capacitor 3, a resistor 4 and a diode 5 is mounted in order to prevent the damage of the Tr 6. Another power supply 1 for charge and a diode 2 for charge are fitted to the capacitor 3 at that time. Accordingly, the lowering section of the charging voltage of the capacitor 3 for the snubber circuit is compensated by another power supply 1 on blocking oscillation and the sudden change of load and the like, thus preventing the saturation of a transformer 7, then obviating the damage of the Tr 6.

Description

[Detailed Description of the Invention] [Field of Application of Industry-1-] This invention (in particular, the snubber circuit of a λ-iffing power supply (J), in which the snubber circuit of a J-bar circuit is This article relates to the snubber circuit of a switching power supply that converts containers into optoelectronics.

[Conventional technology]

The switching power supply uses a <C circuit shown in No. 1 in Fig. 2.

Detects the electrical change I4r applied to the load 101, and controls the control product 10.
2 to drive the PWM drive unit 103 and control the switching transistor 1071 (t, empty the switching current pulse, fl i', N 1 (') 1
The applied voltage is kept constant.

The switching current is reduced to zero from ordinary ships to 116%,
High induced AC power is generated on the primary side of the transformer 108.
Therefore, the emitter of the switching transistor 104
=] The evening moon is high between Reuta 1Ill It'll i)
There is a risk that the switching transistor 104 may be damaged. The snobber circuit is designed to prevent this.
J et Jl, negative '12 figure d\zuichi = 1nden' + 1
(15, 1 resistor 106 o, t, r1' die A-do 1
07, and when the switching current changes from the cutoff value to zero, the primary side of 11. Pass a low resistance of 100 between IIY after charging Y2O2.
Discharge and switch between Suitsuit f-ng 1 and Runsista 1 (14G'
l'4i al jIru.

[Solution? Question 1. - Mila 1111 mentioned snobbery circuit]nTnri10;) is rich n
, l, When used in an energized state, if the voltage exceeds this voltage, the voltage will be absorbed by +1171. ,,this electrical connection 1
141st resistance: 11' on the cap! (discharge (67, switching
Break 1f of 011! Defense: 11.

However, unlike 4R, when the output current is small or the intermittent oscillation of non-continuous current occurs, the oscillation is discontinuous (74, the snubber circuit, etc.) 10h photoelectric weight is F.

Therefore, iQ d: + sudden change 11, etc., τ suddenly changes from 1 to
1 if the magnetic flux to the synth 108 increases? Tsuto? I
RJj' lr (clipped, magnetic flux 1 ~ (N
If the voltage level 108 reaches saturation, the switching transistor 104 will be damaged.

To prevent this, 11 zuru l, = me, also Y come i, L fs visit quickly 4 Ii-i'', 1 (7) 1lil for uldi
l about iQ tt /;-4,), L-=>'/s1 ('J In order to lower the magnetic density so that R is saturated, a transformer of 11 is used.1.- R, Fumi (Following the second person, Ruri77, the inductance of 109 is increased to prevent intermittent oscillations, and it is necessary to link the J-th.

Therefore, the original invention was to connect the -J connector of the snubber circuit from a separate power supply through the diode. Mello circuit g
Q I'+ 1 intermittent oscillation 11. '+A'; J, -r
'f negative i'I! +Sudden91t,'+L,Zl)-IJ,t'l
, the charging current Ff of the bus circuit is lowered.
<x IIT l-,, When the load suddenly changes, etc. -C @ sharply increases 1 to the transformer 1) When ii increases by 1, retouch 1
~Electric clip 34'1, magnetic flux 1. - To prevent the transistor from being damaged (11), prevent the lance from becoming saturated (switching), take the above-mentioned measures and 16 methods! [1 point] to be fit.

Means for Solving the Problem] In order to achieve the objective described in Section 34, the present invention provides a switching L used in a switching power supply circuit that constitutes a DC constant current F1 power supply, etc.・Another voltage source for the snubber circuit of the transistor, which is generated by the circuit such as the auxiliary voltage Aii, and the 11h separate voltage source L.
A diode is installed to charge the circuit from the I source (-J) during intermittent oscillation or sudden load changes, etc.
When the charging voltage of the snubber circuit decreases,
Charge the power supply 1J from the separate power supply to prevent the voltage drop in tF of the power supply 1J in the spring circuit. By ensuring that the transformer can be reset sufficiently, the saturation of the first lance is prevented and the voltage between the switching I, the king of non-transistors, the mink, and the rector is kept within a safe range.
A snubber circuit for a switching N source was constructed.

[Effect] The snubber circuit of this invention is made as follows.

When the load is small and the output is discontinuous for 1hY, A-3
If the oscillation becomes discontinuous due to a sudden load change, etc., the number of pulses decreases, so the number of photoelectric cycles of the snubber circuit decreases, and the charging voltage of the snubber circuit decreases. do. At that time, i! If Q+j is used, a drop in the charging voltage can be prevented by charging the battery from another voltage source through a diode. This prevents damage to the switching transistor.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

An embodiment of the invention is shown in FIG.

Separate power supply for charging 1 for snubber circuit series 3
, the charging diode 2 is nQ I'J. j? by this separate power supply 1 and the snubber circuit z9 of the auxiliary power supply, etc. 4+sa1
Although it may be considered, the specific circuit is omitted in FIG. 1-C.

tξOh, resistor 4 for the snobber circuit and diode 5 (5L)
It is the same as the rank 0.

By this Ii' path, intermittent light 1 dragon time and negative front sudden epidemic 1
1.5 mag. of the snobber circuit;
1i (prevents the saturation of the transformer 7 due to the lower voltage, and prevents the breakdown of the switching 1 transformer (5) R1.

[Ei Song]

As explained in 1-1 above, according to the circuit of the present invention, the intermittent light oscillator and
By reducing the power of the charging circuit to 0, it is possible to prevent the saturation of the 1-lance (damage to the transistor due to J), and the cost of the switching power supply can be reduced.

[Brief explanation of drawings]

Fig. 1 is an explanatory circuit diagram of a switching power supply according to the present invention, and Fig. 2 is a circuit diagram of a conventional switching power supply. Tie 'A-1' for the snobber circuit, 3... Resistor for the snobber circuit, 5... Die A-1' for the snobber circuit, 6... Switching 1 resistor, 7...Trance.

Claims (1)

[Claims] 1. In a snubber circuit of a switching transistor used in an inverter circuit of a switching power supply circuit constituting a DC constant voltage power supply, etc., another voltage source generated in a snubber circuit, etc. of an auxiliary power supply, etc.; A diode is provided to charge the snubber circuit from a separate voltage source, and when the charging voltage of the snubber circuit decreases during intermittent oscillation or sudden load changes, the capacitor of the snubber circuit is charged from the separate power source. A switching power supply characterized by preventing saturation of the transformer and maintaining the voltage between the emitter and collector of the switching transistor within a safe range by preventing a drop in charging voltage and ensuring sufficient reset of the transformer. snubber circuit.