CN101017973B - Switching voltage regulator power regulator peak overcurrent protection device - Google Patents

Abstract

The present invention relates to electronic technology, especially the field of power supply. The invention discloses a peak overcurrent protection device for a switching power supply regulating tube, which is characterized in that: a peak overcurrent sampling circuit R3 is connected in series on the main circuit of the switching power supply regulating tube V , through the diode (or Zener tube) V35 branch connected to the base of the final control tube VN or VP, the peak overcurrent protection can be realized. And in the switching transformer or power frequency transformer T secondary, after being filtered by the same polarity rectifying capacitor C61 of the diode U61, it is used as a detection source, and after the branch circuit of the pressure sensitive switching device D9, the innovative overload shutdown device is connected to realize the power grid overvoltage or Undervoltage shutdown function. It has the advantages of low cost and good performance.

Description

Switching voltage regulator power regulator peak overcurrent protection device

technical field

The invention relates to the field of electronic technology, in particular to the field of television technology.

Background technique

The prior art switching power supply (also known as switching power supply) can be divided into series switching power supply and transformer The two main characteristics of the switching power supply (ie: lifting type, parallel connection). According to the oscillation mode, quasi-resonant fully excited switching power supply and self-excited switching power supply are commonly used now. Quasi-resonant pure it-excited switching power supplies are integrated. The internal circuit is very complex but the external components are small. The oscillator does not need transformer coupling to generate, and only needs reverse polarity rectification and quasi-resonance to delay the synchronous signal. Therefore, it can adapt to a wide fluctuation range of the input power grid and still maintain an excellent switching state. , not like the self-excited switching power supply, the undervoltage fluctuation of the input grid will easily cause insufficient excitation and over-excitation when the input grid is overvoltage. The quasi-resonant other-excited switching power supply uses intermittent PRC oscillation in standby mode, and its own power consumption is very small, which is less than 1W now. Therefore, the quasi-resonant other-excited switching power supply is more and more widely used. However, in the self-excited switching power supply, the switch tube is also an oscillation tube, and the self-excited oscillation is realized through the positive feedback winding of the transformer coupled with the positive feedback network. Although it is simple, reliable and low-cost, the self-excited voltage of the positive feedback winding is proportional to the input power grid Insufficient excitation when the input grid fluctuates due to undervoltage and over-excitation when the grid is overvoltage. Therefore, when the self-excited switching power supply adapts to the fluctuation of the input power grid, the range is not as good as that of the quasi-resonant full other excited switching power supply. Considering the performance/price ratio and reliability: 1. Only the addition of the automatic switching AC power grid rectifying and filtering device of the present invention , (in order to realize the ultra-wide regulated power supply with input grid fluctuations (another patent application). 2. Add the soft start circuit and the intermediate control oscillation technology of the present invention, which can realize low power consumption in standby (another patent application). 3. Add the switch of the present invention Power adjustment tube peak overcurrent protection circuit and overload of the present invention or other abnormal shutdown devices etc., can make the original insufficient self-excited switching power supply performance/price ratio exceed the advantages of integrated quasi-resonant it excited type switching power supply. Prior art switching power supply Its own overload protection circuit is more complicated, can it realize the simplest and most effective switching power supply tube overload protection?

Contents of the invention

The purpose of the present invention is to provide a peak overcurrent protection device for a switching regulator tube power regulating tube, which realizes the overcurrent protection of the switching tube through the maximum peak current flowing through the switching tube, and realizes the simplest and most effective switching power supply tube overload protection.

In order to achieve the above object, the technical solution of the present invention is: a peak overcurrent protection device for a switching power supply regulating tube, which includes an input terminal capacitor, a main output terminal capacitor, a switching power supply regulating tube, a main freewheeling diode, and a switching power supply transformer . The stable control loop is characterized in that a peak overcurrent sampling circuit is connected in series on the main circuit of the switching power supply regulating tube, and the main circuit of the switching power supply regulating tube is also connected to the base of the final control tube or the branch circuit of the switching power supply regulating tube , so as to achieve peak overcurrent protection.

Compared with the prior art, the present invention directly realizes the overcurrent protection of the switch tube by the maximum peak current flowing through the switch tube, and has the advantages of quickness and reliability.

Description of drawings

There are 5 drawings in 1 page. The accompanying drawings are derived from the schematic diagram corresponding to the specific printed circuit board (PCB) of the actual color TV set product. The accompanying drawings of the description are particularly detailed specific embodiments of the essential and essential features of the present invention. Anything not noted in the instructions and drawings (especially components and their reference numbers) shall be interpreted in accordance with legal or common practices. [The circuit components, parameters and their bit numbers only indicate that the schematic diagram of the whole machine corresponds to the physical printed circuit board PCB. Preferred embodiment of the invention specific product reference]. The common terminal "ground" ⊥GND or ⊥ plus other marks of the cold bottom (circuit) board that is not involved in the power grid is equivalent to simplifying the ⊥ mark. In different drawings, containing the same symbols and having the same object means that the functions or performances are the same. Vcc can refer to any high potential end of the power supply. Sometimes in order to distinguish different Vcc, such as: use +B, Z, C+, 5V-1 and other different power supply marks, which can be different power supply voltage values. In the same drawing, except Vcc , those with the same reference number can be connected. Figure 1 or Figure 2 are different embodiments. The switch tubes V shown in the drawings are all field effect switch devices, and crystal triodes can be used. See Figure 3 for an example. Figure 4 or Figure 5 shows an example of a grid overvoltage or undervoltage shutdown circuit.

Detailed ways

The best way to realize the present invention will be described in detail below in conjunction with the accompanying drawings. It is no longer necessary to repeat what has been mentioned above or in combination with the existing technology or should be changed in the same way.

[Example in Fig. 1 ]: after the direct sampling of the present invention, the stable control loop and the soft start circuit 4 pass through the optocoupler N, and then pass through the final control tube VN to modulate the on/off of the switching power supply tube V.

It is taken from the direct rectification wave capacitor Z of the power grid, and is used as the starting resistor through the resistor R1, rectified by the secondary diode U34B of the switching power supply transformer, filtered by the capacitor C34B, and then used as the output terminal bias of the optocoupler N, and applied to the variable voltage switching power supply (ie : Lifting switching power supply, parallel switching power supply) occasions, Zener tube W6 and diode D322 can remove the short circuit. From the positive pole of the power supply C at the main output terminal, it is used as the power supply at the input terminal of the optocoupler N after being divided by the resistor RN and the resistor (or: Zener tube) RN3. The resistance or voltage regulator tube RN3 can be grounded after passing through the capacitor C612, and the capacitor C612 can be used as the power supply for the anti-starting surge current and the relevant circuit of the degaussing relay KB. Capacitor C32 is a soft-start capacitor, which can prolong the time for the voltage rise rate of each output terminal when starting up. The branch circuit of the diode D323 and the regulator tube W323 is connected to the working/standby switching execution circuit.

[Fig. 2 example]: different from Fig. 1, after the direct sampling of the stable control loop and the soft start circuit 4 of the present invention pass through the optocoupler N, then pass through the final control tube VP to modulate the on/off of the switching power supply tube V. It is taken from the direct rectification wave capacitor Z of the power grid, directly used as the starting resistor through the resistor R1, and used as the positive feedback winding N2, through the reverse polarity rectification of the secondary diode U33 of the switching power supply transformer, and filtered by the capacitor C33 to form a negative voltage source for the "ground" as a photoelectric The output end of the coupler N stabilizes the loop power supply, especially as the final control tube VP bias source.

The present invention can be described as follows referring to [Fig. 3 example] to prior art improvement description: the most common self-excited switching power supply of prior art discrete element, derives from Japan Sanyo 80P movement and Sanyo 83PG movement, Sanyo 83PG movement power supply and Sanyo A2/A3/A8 are the same. Referred to as Sanyo A3 power supply. This is that the timing capacitor CB in the power supply positive feedback network is connected in parallel with a diode, and it is better to remove it. This is the improvement of the power supply positive feedback network. Refer to the timing resistance capacitor RB and CB branches in this [Example in Figure 2]. Otherwise, the requirements for the magnification of the VN of the final control tube are very high, and the undervoltage of the power grid is more likely to cause insufficient excitation. The Sanyo A3 power supply and the V emitter of the switch have not added an overcurrent protection detection resistor. Therefore, the peak overcurrent protection detection resistor R3 should be added, and a resistor and diode V35 branch should be added, and the peak overcurrent protection can be realized by connecting the final controller VN. In order to realize the overvoltage or undervoltage shutdown (standby) function of the power grid, the relevant overload shutdown circuit of the present invention can be added with reference to [the example of FIG. 4 or FIG. 5]. The overvoltage or undervoltage shutdown function of the input grid can be realized.

[Example in Figure 5]: Switching transformer or power frequency transformer T secondary, after being filtered by diode U61 and rectifying capacitor C61 with the same polarity, and then through voltage regulator D61 and resistors R118 and R119 to divide the voltage to ground, all the way through the pressure sensitive After the switch device D9 branch is connected to the J7/J7B terminal of the overload shutdown device of the present invention, the power grid overvoltage shutdown function is realized. The other path passes through the pressure-sensitive switch device ZD9B and the diode D9B branch, and then continuously controls the J8 terminal in the overload shutdown device of the present invention to realize the power grid undervoltage protection or the plug contact failure protection shutdown function. After passing through the voltage dividing resistor R118/R119, it can be connected to the OPT interface of the microcontroller CPU custom terminal. The value of grid voltage can be displayed on the screen. The overload detection source can be processed by the microcontroller CPU, and a shutdown command is issued when overloading, which can realize the ACOFF or DCOFF function. The low potential end of the secondary detection capacitor C61 of the inductive impedance coil L of the switching power supply connected in series (namely: the switching transformer T) can be superimposed on the positive pole of other power supplies. There is no need for a transformer switching power supply. The regulator tube D61 can be replaced by a resistor.

[Example in Figure 4] negative pressure detection source, the principle is the same as [Example in Figure 5] positive pressure detection source. [Example in Figure 4]: After filtering by diode U61 and rectifying capacitor C61 of the same polarity, the rectifying capacitor C61 of the same polarity filters and outputs a negative pressure detection source. After one path passes through the D9 branch of the pressure-sensitive switch device, the terminal J8 in the overload shutdown device of the present invention is continuously controlled to realize the function of power grid undervoltage protection or poor contact protection of the plug. The other path passes through the pressure-sensitive switch device ZD9B and the diode D9B branch, and continuously controls the endpoint J7/J7B in the overload shutdown device of the present invention to realize the power grid overvoltage shutdown function. After passing through the voltage dividing resistor R118/R119, it can be connected to the OPT interface of the microcontroller CPU custom terminal, and the value of the grid voltage can be displayed on the screen.

Claims (3)

1. peak over-current protection of switch voltage stabilization power adjusting pipe device; include switching mode power supply transformer (T); input end capacitor (Z); main output capacitor (C); the Switching Power Supply adjustment pipe (V) that is connected with input end capacitor (Z); photoelectrical coupler (N); the steady control loop (4) that is connected with photoelectrical coupler (N); it is characterized in that: serial connection peak value overcurrent sample resistance (R3) on Switching Power Supply adjustment pipe (V) major loop; Switching Power Supply adjustment pipe (V) major loop also is connected in the base stage of whole keyholed back plate (VN) by diode (V35) branch road; steady control loop (4) is connected to whole keyholed back plate (VN) by photoelectrical coupler (N); by the break-make of whole keyholed back plate (VN) modulating switch power source adjustment pipe (V), thereby realize peak over-current protection.

2. according to the described peak over-current protection of switch voltage stabilization power adjusting pipe device of claim 1, it is characterized in that: switching mode power supply transformer (T) secondary, after second diode (U61) and same polarity commutation capacitor (C61) filtering, form the positive-pressure type detection resources, pass through the dividing potential drop of voltage-stabiliser tube (D61) and first resistance (R118), second resistance (R119) again, wherein, an end ground connection of second resistance (R911); In addition, have a node to draw two branch roads between first resistance (R118) and second resistance (R119), wherein this two branch road connects an overload shutdown unit by the first pressure sensitive switch device (D9), the second pressure sensitive switch device (ZD9B) respectively.

3. according to the described peak over-current protection of switch voltage stabilization power adjusting pipe device of claim 1, it is characterized in that: switching mode power supply transformer (T) secondary, through output suction type detection resources after second diode (U61) and same polarity commutation capacitor (C61) filtering, pass through the dividing potential drop of voltage-stabiliser tube (D61) and first resistance (R118), second resistance (R119) again, wherein first resistance (R118) also connects power supply (VCC); In addition, draw between first resistance (R118) and second resistance (R119) branch road through the first pressure sensitive switch device (D9) after, connect an overload shutdown unit; And draw between voltage-stabiliser tube (D61) and second resistance (R119) branch road through the second pressure sensitive switch device (ZD9B) and the 3rd diode (D9B) after, be connected to described overload shutdown unit, realize electrical network overvoltage shutdown function.

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