CN2404626Y

CN2404626Y - Control circuit device for anti magnetic biasing for switch power supply

Info

Publication number: CN2404626Y
Application number: CN 99235012
Authority: CN
Inventors: 蔡晓
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-10-19
Filing date: 1999-10-19
Publication date: 2000-11-08
Anticipated expiration: 2009-10-19

Abstract

The utility model relates to a control circuit device for anti magnetic biasing for switch power supply. In the circuit of the all-bridge arc-welding inverter, the load variation is big, and easily generates accumulation phenomenon of the direct current magnetic biasing. The utility model can use the inverse addition arithmetic device and the comparator to form the feedback circuit of the peak current; when some current waveform in the circuit of the all-bridge arc-welding inverter quickly increases because of the magnetizing current, the feedback circuit of the peak current of the utility model sends out a pulse signal into the PWM master control chip and makes the feedback circuit shut off in advance; hence the phenomenon of electric current magnetic biasing and hard switch can be avoided. The oblique wave cancelling circuit can be added, so that the control circuit device is adopted to improve operating stability, reduce cost, and use widely.

Description

The control circuit device of the anti-magnetic bias of Switching Power Supply

The utility model relates to the control circuit device of the anti-magnetic bias of a kind of Switching Power Supply.

In the prior art, high-power Arc Welding Power and close device and adopt full bridge circuit, so the transformer utilization factor height, electric current and voltage distribution are reasonable.But in welding process, load variations is fast, load-short circuit often occurs, the situation of short circuit-zero load, and electric current changes violent, so phenomenons such as D.C. magnetic biasing accumulation and hard switching take place full-bridge circuit easily.Adopt the strict high power valve of selecting, strengthen the transformer core air gap.Series capacitance on the primary winding, stopping direct current voltage etc. prevents the measure of magnetic bias, does not all have to accumulate the root knot of this problem existence and solution completely at the electric current magnetic bias.

It is low that the purpose of this utility model provides a kind of cost, highly versatile, the control circuit device of the anti-magnetic bias of Switching Power Supply that job stability is high.

In order to achieve the above object, the utility model adopts technical scheme to be:

The anti-magnetic bias control circuit of a kind of Switching Power Supply device, its special character is: above-mentioned control circuit device comprises Hall element 1, ramp generator 2, anti-phase adder calculator 3, and voltage comparator 4; Two of Switching Power Supply drives the input of the output termination ramp generator 2 of signal A, B, the output of the current signal i of the output of ramp generator 2 and Hall element inserts the inverting input of anti-phase adder calculator 3, the inverting input of the output termination voltage comparator 4 of anti-phase adder calculator 3, the normal phase input end of voltage comparator 4 inserts voltage Vg, and its output inserts the PWM main control chip.

Described ramp generator 2 is adjustable ramp generator.

Described Hall element 1 is a magnetic compensation formula current sensor.

The utility model is described in further detail below in conjunction with the drawings and specific embodiments:

Fig. 1 is a full-bridge type inverter schematic diagram;

The current waveform figure of Fig. 2 when slight magnetic bias takes place;

The current waveform figure of Fig. 3 when serious magnetic bias takes place;

Fig. 4 is a connecting circuit block diagram of the present utility model;

Fig. 5 is internal wiring figure of the present utility model;

Referring to Fig. 1, in the circuit of full-bridge type arc welding inverter, according to the computing formula of the separated exciting full-bridge circuit number of turn: Np=50*U*T _ON/ (B*S) derive transformer magnetic induction density B=50*U*T _ON/ (Np*S), N wherein _PBe the primary number of turn, U is the added voltage of transformer duration of work, T _ONBe the width of conducting pulse, S is the net sectional area of transformer core.Because of the added voltage U of transformer duration of work and pulse signal by control circuit when power stage is transmitted, the width T of its conducting pulse _ONIt is constant all to be difficult to assurance, so bias phenomenon will take place.At this moment, though magnetic induction density B with T _ONThe still linear increase of increase, but magnetizing current increases sharply, a layer phenomenon occurring sticking up as Fig. 2 current wave is that magnetizing current increases sharply and causes.When magnetic bias seriously accumulated, serious deformation as shown in Figure 3 took place in current waveform.

The utility model adopts peak point current by all feedbacks, can set up the generation that the oblique wave compensation circuit is controlled bias phenomenon in the circuit of full-bridge type arc welding inverter.This control circuit detects primary current by week, and its and a given voltage are compared, and when a certain Zhou Fasheng of electric current stuck up the tail phenomenon, some turn-offed control circuit in advance with this week, thereby prevents magnetic bias from accumulating and the influence that causes.As Fig. 4, the external circuit of this device is from will the flow through current signal i input magnetic bias resisting device of high power valve of the integrated signal C of PWM main control chip output and Hall element, and after this device computing, output feedback signal G is to pwm chip.

Internal wiring figure below in conjunction with this device of Fig. 5 introduces this device course of work in detail.This device comprises ramp generator 2 and anti-phase adder calculator 3 and voltage comparator 4 and Hall element 1.To the flow through inverting input of the detected signal i of current signal input inversion adder calculator 3 of high power valve of magnetic compensation formula Hall current sensor 1.And through two driving A, the B of PWM main control chip input behind ramp generator 2, the signal D of its output is the inverting input of input inversion adder calculator 3 also.Computing output pulse signal F through anti-phase adder calculator 3.Because of the ramp signal and two driving pulse A, the B that take place through ramp generator wide synchronously, also with regard to and the measured current signal of Hall current sensor synchronous, wide.So behind anti-phase arithmetic unit 3, ramp signal D plays an effect that increases the current signal slope.Being increased the reversed-phase output of pulse signal F input voltage comparator 4 of slope and the control signal Vg of an appointment compares, when peak value reaches Vg, the comparator upset, export a spike signal and give the PWM controller, thereby this week is turn-offed, thereby realize that magnetic bias can't accumulate, and makes magnetization curve be operated in linear stage always by week control.So prevent D.C. magnetic biasing and hard switching phenomenon.In this device,, can produce the pulse signal of Different Slope, thereby produce different signal amplification effects by regulating ramp generator.This device also being suitable in PWM phase-shift soft switch (ZVS) circuit.

The utility model pursues all feedback circuits and oblique wave compensation circuit owing to anti-biasing circuit device adopts peak point current, thereby has the following advantages:

1. the job stability height feeds back by week because adopting peak point current, thereby magnetic bias can't be accumulated, magnetization Curve is always in linearity range work, thereby the stability of complete machine has obtained effective assurance.

2. cost is low, owing to need not to adopt the way that strengthens iron core air gap, strengthens into original increase magnetic bias license Scope improves anti-magnetic bias ability.

3. highly versatile because this device adds the PWM governor circuit, does not affect master control under normal condition So circuit working is all available to any PWM control and any control mode.

Claims

1, the anti-magnetic bias control circuit of a kind of Switching Power Supply device is characterized in that: above-mentioned control circuit device comprises Hall element (1), ramp generator (2), anti-phase adder calculator (3), and voltage comparator (4); Two of Switching Power Supply drives the input of the output termination ramp generator (2) of signal A, B, the output of the output of ramp generator (2) and the current signal i of Hall element inserts the inverting input of anti-phase adder calculator (3), the inverting input of the output termination voltage comparator (4) of anti-phase adder calculator (3), the normal phase input end of voltage comparator (4) inserts voltage Vg, and its output inserts the PWM main control chip.

2, the control circuit device of the anti-magnetic bias of Switching Power Supply according to claim 1 is characterized in that: described ramp generator (2) is adjustable ramp generator.

3, the control circuit device of the anti-magnetic bias of Switching Power Supply according to claim 1 and 2 is characterized in that: described Hall element (1) is a magnetic compensation formula current sensor.