CN104821726A - Electron beam welding machine power supply high-voltage voltage stabilization method and method employing micro ripper Cuk type converter - Google Patents

Abstract

The invention discloses an electron beam welding machine power supply high-voltage voltage stabilization method and method employing a micro ripper Cuk type converter. The method comprises the following steps: (1), after a three-phase AC power supply is subjected to boosting, rectification and filtering, high voltage is obtained; (2), the high voltage passes through a DC converter, an on-off duty ratio is controlled for adjusting output voltage; (3), the output voltage passes through a PID circuit and a PWM circuit, the duty ratio of a power device is controlled, and the size of the output voltage can be adjusted; and (4), needed voltage is obtained at an output capacitor. The apparatus further comprises a boost rectification filtering circuit, a Cuk main circuit, a control circuit and an output circuit. According to the invention, the Cuk main circuit is introduced in a switch power supply circuit, two inductors of the Cuk circuit are coupled by use of the property of the coupling inductors, the coupling degree of the inductors is reasonably distributed, the circuit ripples are substantially reduced, a feedforward circuit is additionally arranged to enable fluctuations generated at an input end to be directly adjusted from the input end, the control adjustment speed of a whole power supply system is enabled to be higher and more stable, the structure is simple, the control is easy, and the cost is low.

Description

A kind of electron beam welding electromechanical source high voltage stabilizing method and device adopting micro-ripple Cuk formula converter

Technical field

The present invention relates to high-voltage switch power supply device, particularly a kind of electron beam welding electromechanical source high voltage stabilizing method and device adopting micro-ripple Cuk formula converter.

Background technology

Electron beam welding machine (Electron Beam Welding is called for short EBW) high-voltage-stable power supply is mainly used in as electron gun provides accelerating voltage, and the quality of its performance directly decides electro-beam welding process and welding quality.It is high that its power supply has efficiency.Energy density is large.The series of advantages such as voltage stabilized range is wide, obtain applying more and more widely, but due to its exist intrinsic high ripple output voltage, its scope of application is restricted.But Switching Power Supply will inevitably produce ripple due to himself structure, but the capacitor filtering of high tension voltage needs certain capacitance can only select the electric capacity of low capacity rank under elevated pressure conditions, because converter capacitance current has very large peak current therefore also may there will be the possibility of condenser failure, another is that the frequency of high-voltage switch power supply breaker in middle device also has a lot of restriction, because consider on the one hand and improve the size that switching frequency will reduce inductance, electric capacity, transformer, harmonic content can be reduced like this; On the other hand, switching frequency is too high can cause larger switching loss again, and the efficiency of converter can be decreased, and therefore output ripple becomes critical problem in Switching Power Supply.

In prior art, filter method filtering output ripple is adopted to be one of conventional method, filter comprises active, passive filter, filter parallel connection or some resistance capacitances of connecting in output loop realize, the method must calculate ripple frequency characteristic by rigorous in detail, thus select accurate resistance and capacitance, the method is once electric capacity, resistance failure or resistance and capacitance calculate inaccuracy, likely be mixed into new ripple, noise, increase output ripple on the contrary, the method is applicable to small-power switching power-supply, different losses is had in the powerful Switching Power Supply of big current, the volume of Switching Power Supply also can increase thereupon.

What one of them principal element produced due to Switching Power Supply ripple was switching tube opens shutoff, therefore the circuit of switch point cutting edge of a knife or a sword pulse can be absorbed in switching tube partial design, but the method is applicable to the external topological structure of switch, integration module for some built-in integrated switch pipes is just helpless, and the method needs accurately complicated calculating, operability is poor.

Direct current source increases high frequency line and crosses technology, the ripple that processing unit reduces Switching Power Supply is crossed by increasing high frequency line at direct current source, but this scheme needs to increase extra control loop and complicated auxiliary circuit, price comparison is high, and whole switch power supply system is made up of discrete component, there is the deficiency that integrated level is poor and power density is low.

In momentum control technology, propose momentum control technology based on impulse equivalency principle as the one-cycle control technique, and be applied in direct-current switch power supply to eliminate the output low frequency ripple of direct-current switch power supply, have employed the simulation study that BUCK (buck converter) circuit carries out to show: its output low frequency ripple is also just less than 5mV in theory simultaneously, be not eliminate completely, limit frequency and the output voltage of high-voltage switch power supply, be of limited application.

The problem of high-voltage switch power supply output ripple, it is the technical barrier existing for high-power high voltage stabilized voltage power supply always, simultaneously in traditional voltage mode control, no matter inside circuit where produces interference, finally all will could obtain adjustment through feedback circuit, and have impact on the speed of adjustment, in system, the change of any position all will pass to output, and system just can be made to make corresponding adjustment after feedback, the dynamic response characteristic of such system is poor.

Summary of the invention

The object of the invention is for the deficiencies in the prior art, and a kind of the electron beam welding electromechanical source high voltage stabilizing method and the device that adopt micro-ripple Cuk formula converter are provided, the method is less demanding to input voltage, the direct voltage of output smoothing, output ripple is little, and adjustable output ripple current ripple size, drops to minimum by output ripple current ripple, simple to operate, do not need the calculating of large amount of complex, derivation; The volume of this device is little, and efficiency of transmission is high, and anti-electrical network interference performance is comparatively strong, and the loss of mains switch is little.

Realize the technical scheme of the object of the invention:

Adopt an electron beam welding electromechanical source high voltage stabilizing method for micro-ripple Cuk formula converter, comprise the steps:

1) three-phase alternating-current supply is after boosting, rectification, filtering, obtains high tension voltage;

2) high tension voltage is through DC converter, adjusts output voltage by the break-make duty ratio of control switch device;

3) output voltage passing ratio integral differential rate of change controller (Proportional-Integral-DifferentialController, be called for short PID) outer voltage and current inner loop feedback, and compare with set point, the voltage of the error relatively drawn as control signal through pulse-width modulation (Pulse Width Modulation, be called for short PWM) circuit, by controlling the duty ratio of power device, the size of output voltage can be adjusted;

4) the minimum high voltage stabilizing output voltage of ripple is obtained at output capacitance place.

Step 2) in DC converter be Cuk circuit:

Cuk circuit comprises input inductance L ₁with outputting inductance L ₂, two inductance L ₁, L ₂between intercouple, as switching tube V _tduring conducting, inductance L ₁in electric current linear growth, electric capacity C ₁pass through V _tand L ₂form discharge loop, diode V _dbe in reverse-biased, inductance L ₁and L ₂between coefficient of mutual inductance be M, following formula of can deriving

$\left\{\begin{array}{c}{U}_i=L_1{\mathrm{di}}_1/\mathrm{dt}+{\mathrm{Mdi}}_2/\mathrm{dt}\\ U_i=L_2{\mathrm{di}}_2/\mathrm{dt}+{\mathrm{Mdi}}_1/\mathrm{dt}\end{array}\right.---\left(1\right)$

U in formula _ithe input voltage of Cuk circuit, di ₁/ dt is input inductance L ₁current changing rate, di ₂/ dt is outputting inductance L ₂current changing rate, M is coefficient of mutual inductance.

Can be obtained by formula (1) $\left\{\begin{array}{c}\frac{{\mathrm{di}}_1}{\mathrm{dt}}=\frac{U_i(1-M/L_2)}{L_1(1-M^2/L_1{L}_2)}\\ \frac{{\mathrm{di}}_2}{\mathrm{dt}}=\frac{U_i(1-M/L_1)}{L_2(1-M^2/L_1{L}_2)}\end{array}\right.---\left(2\right)$

U in formula _ithe input voltage of Cuk circuit, di ₁/ dt is input inductance L ₁current changing rate, di ₂/ dt is outputting inductance L ₂current changing rate, M is coefficient of mutual inductance.

Order

$\begin{array}{cc}{L}_{1\mathrm{eq}}=\frac{L_1(1-M/\left(L_1{L}_2\right))}{1-M/L_2},& L_{2\mathrm{eq}}=\frac{L_2(1-M/\left(L_1{L}_2\right))}{1-M/L_1}\end{array}$

Then formula (2) is reduced to

$\left\{\begin{array}{c}{\mathrm{di}}_1/\mathrm{dt}=U_i/L_{1\mathrm{eq}}\\ {\mathrm{di}}_2/\mathrm{dt}=U_i/L_{2\mathrm{eq}}\end{array}\right.---\left(3\right)$

U in formula _ibe the input voltage of Cuk circuit, M is coefficient of mutual inductance, di ₁/ dt is input inductance L ₁current changing rate, di ₂/ dt is outputting inductance L ₂current changing rate.

Obviously, L is strengthened _1eqand L _2eqnumerical value just can reduce L ₁or L ₂in ripple current.If meet L in circuit ₁=L ₂=M, now in Cuk circuit, input ripple current and output ripple electric current can reduce to zero, but because magnetic device is because of design and processing, component couples COEFFICIENT K is always less than 1.

For analyzing K to the impact of circuit ripple, L can be established ₁and L ₂turns ratio then L _1eqand L _2eqexpression formula become

$\left\{\begin{array}{c}{L}_{1\mathrm{eq}}=L_1(1-K^2)/(1-\mathrm{nK})\\ L_{2\mathrm{eq}}=L_2(1-K^2)/(1-K/n)\end{array}\right.---\left(4\right)$

In formula, K is the coupling coefficient of element.

From formula (4), as nK=1, L ₁input ripple current is zero ripple current, as K=n, and L ₂in output ripple electric current be the even zero ripple current requirement of micro-ripple, make input and output electric current level and smooth.

In like manner adopt above-mentioned derivation formula can draw as switching tube V _tturn off, diode V _dl during conducting ₁and L ₂current changing rate di ₁/ dtdi ₂/ dt computing formula:

$\left\{\begin{array}{c}{\mathrm{di}}_1/\mathrm{dt}=-U_0/L_{1\mathrm{eq}}\\ {\mathrm{di}}_2/\mathrm{dt}={-U}_0/L_{2\mathrm{eq}}\end{array}\right.---\left(5\right)$

$\begin{array}{cc}{L}_{1\mathrm{eq}}=\frac{L_1(1-M/\left(L_1{L}_2\right))}{1-M/L_2}& L_{2\mathrm{eq}}=\frac{L_2(1-M/\left(L_1{L}_2\right))}{1-M/L_1}\end{array}$

M is coefficient of mutual inductance, U _oit is the output voltage of Cuk circuit.

No matter for switching tube V _dconducting, diode V _dcut-off or switching tube V _tcut-off, diode V _din ON operation situation, for L ₁, L ₂, K and L ₁and L ₂current changing rate di ₁/ dt, di ₂relation between/dt all can according to formula

(4) adjust, realize the requirement of the micro-ripple of Cuk circuit.

Step 2) in also introduce and inverse lead diode, on the switching tube side of Cuk circuit, a diode in parallel is used for protecting triode, prevents reverse breakdown.

Step 3) middle output voltage is first through over-sampling, starting, overcurrent and overvoltage protection, overheat protector and noise filter circuit, and detection output voltage changes; PID control circuit is made up of three parts: current inner loop and, outer voltage and overcurrent protection three part;

Output voltage U _oreal output value is obtained through sample circuit, this voltage can as the actual value of PID adjuster and and set point compare after correcting action, delivered in pwm circuit by PID control circuit output control signal and adjust pulsewidth, this also forms conventional Voltage Feedback, i.e. outer voltage.

Cuk circuit breaker in middle pipe V _temitter and Hall current sensor T _aconnect, Hall current sensor T _ato, by tested size of current, select suitable no-load voltage ratio by current signal I _stransfer to export and change into voltage signal and output in PID control circuit and compare with set point and correct, once voltage deviation set point be detected, current sense comparator will make PWM latch reset, gate drive signal will export pulse to power switch pipe and regulate, before output sampled voltage error occurs, the pulse of pwm circuit exports and just has regulating action, what feedforward compensation circuit detected is disturbance itself, as long as the change that occurs utility grid voltage, will synchronously carry out detecting and compensating at once, so just transient voltage error can be reduced to minimum, form current feedback inner ring.

These two feedbacks finally change into control signal and deliver to described pwm circuit, constitute voltage and current double closed-loop structure, reach and compensate the stable effect exported.

Excessive surge current affects Circuits System and normally works, and causes very large impact to circuit and device.Therefore, current-limiting apparatus must be designed to be limited it.Hall current sensor is adopted to carry out over-current detection in the present invention, its operation principle is: when Hall current sensor is greater than set point at the current value that load outputs detects, output signal forces pwm signal to be 0, thus shutdown switch element makes electric current no longer rise.This method current limliting is accurate, effectively can prevent short circuit, overcurrent protection easy to implement.

Pwm circuit produces a control signal by error amplifier, it acts on PWM comparator, the sawtooth waveforms that the amplitude produced with control chip internal oscillator is fixed compares generation pwm signal, this road pwm signal again through with the effect of clock pulse after produce the adjustable pwm signal of the duty ratio that is finally used for controlling power switch pipe, therefore the realization that described pwm circuit regulates automatically is realize by feedback and error amplifier completely, when load current reduces or DC input voitage raises, capital causes the rising of output voltage, at this moment the feedback voltage of system increases, control signal reduces, the pulsewidth exported is made to narrow thus output voltage is reduced.

Step 4) high voltage stabilizing output voltage, the electronics that the cathode filament for load electron gun is overflowed provides accelerating field.

Adopt an electron beam welding electromechanical source high voltage stabilizing device for micro-ripple Cuk formula converter, comprise boosting current rectifying and wave filtering circuit, Cuk main circuit, control circuit, output circuit;

The effect of described boosting current rectifying and wave filtering circuit obtains level and smooth high tension voltage, and boosting current rectifying and wave filtering circuit is made up of three-phase transformer booster circuit and current rectifying and wave filtering circuit;

Power conversion is carried out in the effect of described Cuk main circuit, pressure regulation, the effect suppressing current pulsation ripple can also be played, Cuk main circuit comprises input inductance and outputting inductance, intercouple between inductance, input and output capacitors, output diode and power switch transistor and inversely lead diode, input inductance and input capacitance and power switch transistor, be connected against leading diode common port, one end of outputting inductance is connected with the common port of output diode with input capacitance, the other end is connected with output capacitance, output capacitance is the input of output circuit, the grid of power switch transistor is control input end, the transmitting very current feedback terminal of power switch transistor,

The effect of described control circuit produces actual electric current and voltage value by the feedback of two close cycles to produce control signal through pwm circuit compared with set point voltage, control the duty ratio of power device, reach the effect of stable welding line, control circuit comprises pwm circuit, PID control circuit, two Hall current sensor circuit.In control circuit, pwm circuit is connected with PID control circuit, PID control circuit is connected with two Hall current sensor circuit, the output of pwm circuit is the output of control circuit, the input of PID control circuit is the input of control circuit, the output of two Hall current sensor circuit is respectively current input terminal and the overcurrent protection end of control circuit, and PID control circuit is connected with setting value circuit simultaneously;

Described output circuit is made up of overcurrent protection resistance, choke induction, fly-wheel diode, load variable resistor, overcurrent protection resistance is connected with fly-wheel diode, choke induction, choke induction and fly-wheel diode are in parallel, and the input of overcurrent protection resistance is the input of output circuit;

The output of boosting current rectifying and wave filtering circuit is connected with the input of Cuk main circuit, the control input end of Cuk main circuit is connected with the output of control circuit, the output of Cuk main circuit is connected with the input of output circuit, and the input of control circuit is connected with the output of output circuit;

Beneficial effect of the present invention, the method draws the requirement realizing micro-ripple in Switching Power Supply after two coupling inductances are carried out simple coupled operational, in controlling unit, adopt double-loop circuit theoretical, introduce this link of current feedback, feed-forward regulation effect is had to output voltage, improve the dynamic response of system, in system during curent change, duty ratio and PID circuit can comparatively fast regulate, the change of the direct tracking error voltage of inductive current, output voltage just can be controlled, current inner loop also makes switching power converters be easy to realize parallel running, be conducive to realizing Cuk circuit design, system output current pulsation ripple is little, there is very strong operability, Systematical control governing speed is higher, more stable, there is very high market using value,

This device introduces Cuk converter circuit in switch power module circuit, all inductance element is contained in the input and output link of circuit, so the ripple of input and output is lower, and there is no the restriction that buck is single like this, needed for Cuk main circuit topological structure, components and parts are few, the simplicity of design of drive circuit, compare direct current source increase the high frequency line technology of crossing be a kind of can with minimum components and parts, obtain the circuit structure of more satisfactory power transfer characteristic, the calculating of the circuit parameter of Cuk circuit realiration zero ripple is also some basic computings, there is no huge specific calculations mode, therefore simple compared with switch point cutting edge of a knife or a sword impulse circuit design and structure is simple, control easily, with low cost.

Accompanying drawing explanation

Fig. 1 is the electrical schematic diagram of high voltage stabilizing Switching Power Supply of the present invention in embodiment.

Embodiment

Below in conjunction with drawings and Examples, content of the present invention is further elaborated, but is not limitation of the invention.

Embodiment:

Adopt an electron beam welding electromechanical source high voltage stabilizing method for micro-ripple Cuk formula converter, comprise the steps:

1) three-phase alternating-current supply is after boosting, rectification, filtering, obtains high tension voltage;

2) high tension voltage is through DC converter, adjusts output voltage by the break-make duty ratio of control switch device;

3) output voltage passing ratio integration rate of change controller (Proportional-Integral-DifferentialController, be called for short PID) outer voltage and current inner loop feedback, and compare with set point, the voltage (whether correct writing like this) of the error relatively drawn is through pulse-width modulation (Pulse Width Modulation, be called for short PWM) circuit, by controlling the duty ratio of power device, the size of output voltage can be adjusted;

4) the minimum high voltage stabilizing output voltage of ripple is obtained at output capacitance place.

Step 2) in DC converter be Cuk circuit:

Cuk circuit comprises input inductance L ₁with outputting inductance L ₂, two inductance L ₁, L ₂between intercouple, as switching tube V _tduring conducting, inductance L ₁in electric current linear growth, electric capacity C ₁pass through V _tand L ₂form discharge loop, now diode V _dbe in reverse-biased, inductance L ₁and L ₂between coefficient of mutual inductance be M, following formula of can deriving

$\left\{\begin{array}{c}{U}_i=L_1{\mathrm{di}}_1/\mathrm{dt}+{\mathrm{Mdi}}_2/\mathrm{dt}\\ U_i=L_2{\mathrm{di}}_2/\mathrm{dt}+{\mathrm{Mdi}}_1/\mathrm{dt}\end{array}\right.---\left(1\right)$

U in formula _ithe input voltage of Cuk circuit, di ₁/ dt is input inductance L ₁current changing rate, di ₂/ dt is outputting inductance L ₂current changing rate, M is coefficient of mutual inductance.

Can be obtained by formula (1) $\left\{\begin{array}{c}\frac{{\mathrm{di}}_1}{\mathrm{dt}}=\frac{U_i(1-M/L_2)}{L_1(1-M^2/L_1{L}_2)}\\ \frac{{\mathrm{di}}_2}{\mathrm{dt}}=\frac{U_i(1-M/L_1)}{L_2(1-M^2/L_1{L}_2)}\end{array}\right.---\left(2\right)$

U in formula _ithe input voltage of Cuk circuit, di ₁/ dt is input inductance L ₁current changing rate, di ₂/ dt is outputting inductance L ₂current changing rate, M is coefficient of mutual inductance.

Order

$\begin{array}{cc}{L}_{1\mathrm{eq}}=\frac{L_1(1-M/\left(L_1{L}_2\right))}{1-M/L_2},& L_{2\mathrm{eq}}=\frac{L_2(1-M/\left(L_1{L}_2\right))}{1-M/L_1}\end{array}$

Then formula (2) is reduced to

$\left\{\begin{array}{c}{\mathrm{di}}_1/\mathrm{dt}=U_i/L_{1\mathrm{eq}}\\ {\mathrm{di}}_2/\mathrm{dt}=U_i/L_{2\mathrm{eq}}\end{array}\right\}---\left(3\right)$

U in formula _ibe the input voltage of Cuk circuit, M is coefficient of mutual inductance, di ₁/ dt is input inductance L ₁current changing rate, di ₂/ dt is outputting inductance L ₂current changing rate.

Obviously, L is strengthened _1eqand L _2eqnumerical value just can reduce L ₁or L ₂in ripple current.If meet L in circuit ₁=L ₂=M, now in Cuk circuit, input ripple current and output ripple electric current can reduce to zero, but because magnetic device is because of design and processing, component couples COEFFICIENT K is always less than 1.

For analyzing K to the impact of circuit ripple, L can be established ₁and L ₂turns ratio then L _1eqand L _2eqexpression formula become

$\left\{\begin{array}{c}{L}_{1\mathrm{eq}}=L_1(1-K^2)/(1-\mathrm{nK})\\ L_{2\mathrm{eq}}=L_2(1-K^2)/(1-K/n)\end{array}\right\}---\left(4\right)$

In formula, K is the coupling coefficient of element.

From formula (4), as nK=1, L ₁input ripple current is zero ripple current, as K=n, and L ₂in output ripple electric current be the even zero ripple current requirement of micro-ripple, make input and output electric current level and smooth.

In like manner adopt above-mentioned derivation formula can draw as switching tube V _tturn off, diode V _dl during conducting ₁and L ₂current changing rate di ₁/ dt

Di ₂the computing formula of/dt:

$\left\{\begin{array}{c}{\mathrm{di}}_1/\mathrm{dt}=-U_0/L_{1\mathrm{eq}}\\ {\mathrm{di}}_2/\mathrm{dt}={-U}_0/L_{2\mathrm{eq}}\end{array}\right.---\left(5\right)$

$\begin{array}{cc}{L}_{1\mathrm{eq}}=\frac{L_1(1-M/\left(L_1{L}_2\right))}{1-M/L_2}& L_{2\mathrm{eq}}=\frac{L_2(1-M/\left(L_1{L}_2\right))}{1-M/L_1}\end{array}$

M is coefficient of mutual inductance, U _oit is the output voltage of Cuk circuit.

No matter for switching tube V _tconducting, diode V _dcut-off or switching tube V _tcut-off, diode V _din ON operation situation, for L ₁, L ₂, K and L ₁and L ₂current changing rate di ₁/ dt, di ₂relation between/dt all can be adjusted according to formula (4), realizes the requirement of the micro-ripple of Cuk circuit.

Step 2) on the power switch pipe side of Cuk circuit one in parallel inversely lead diode V _rprotect power switch pipe V _t, prevent reverse breakdown.

Step 3) middle output voltage is first through over-sampling, starting, overcurrent and overvoltage protection, overheat protector and noise filter circuit, and detection output voltage changes; PID feedback control circuit is made up of three parts: current inner loop, outer voltage and overcurrent protection three part;

Power switch pipe V in Cuk circuit _temitter and Hall current sensor T _aconnect, Hall current sensor T _ato, by tested size of current, select suitable no-load voltage ratio by current signal I _stransfer to export and change into voltage signal and output in PID control circuit and compare with set point and correct, once voltage deviation set point be detected, current sense comparator will make PWM latch reset, gate drive signal will export pulse to power switch pipe and regulate, before output sampled voltage error occurs, the pulse of pwm circuit exports and just has regulating action, what feedforward compensation circuit detected is disturbance itself, as long as the change that occurs utility grid voltage, will synchronously carry out detecting and compensating at once, so just transient voltage error can be reduced to minimum, form current feedback inner ring.

These two feedbacks finally change into control signal and deliver to described pwm circuit, constitute voltage and current double closed-loop structure, reach and compensate the stable effect exported.

Excessive surge current affects Circuits System and normally works, and causes very large impact to circuit and device.Therefore, current-limiting apparatus must be designed and restriction is added to it.Hall current sensor T is adopted in the design _bcarry out over-current detection, its operation principle is: when Hall current sensor is greater than set point at the current value that load outputs detects, output signal forces pwm signal to be 0, thus shutdown switch element makes electric current no longer rise.This method current limliting is accurate, effectively can prevent short circuit, overcurrent protection easy to implement.

Pwm circuit produces a control signal by error amplifier, it acts on PWM comparator, the sawtooth waveforms that the amplitude produced with control chip internal oscillator is fixed compares generation pwm signal, this road pwm signal again through with the effect of clock pulse after produce the adjustable pwm signal of the duty ratio that is finally used for controlling power switch pipe, therefore the realization that described pwm circuit regulates automatically is realize by feedback and error amplifier completely, when load current reduces or DC input voitage raises, capital causes the rising of output voltage, at this moment the feedback voltage of system increases, control signal reduces, the pulsewidth exported is made to narrow thus output voltage is reduced.

Step 4) high voltage stabilizing output voltage, the electronics that the cathode filament for load electron gun is overflowed provides accelerating field.

As shown in Figure 1, adopt the electron beam welding electromechanical source high voltage stabilizing device of micro-ripple Cuk formula converter, comprise boosting current rectifying and wave filtering circuit 1, Cuk main circuit 2, control circuit 3, output circuit 4;

The effect of described boosting current rectifying and wave filtering circuit 1 obtains level and smooth high tension voltage, and boosting current rectifying and wave filtering circuit 1 is made up of three-phase transformer booster circuit and current rectifying and wave filtering circuit;

Power conversion, pressure regulation are carried out in the effect of described Cuk main circuit 2, and can also play the effect suppressing current pulsation ripple, Cuk main circuit 2 comprises input inductance L ₁with outputting inductance L ₂, between inductance, there is coupled relation, input capacitance C ₁with output capacitance C ₂, output diode V _ddiode V is led with inverse _rand power switch transistor V _t, input inductance L ₁with input capacitance C ₁with power switch transistor V _t, inverse lead diode V _rcommon port be connected, outputting inductance L ₂one end and input capacitance C ₁with output diode V _dcommon port be connected, the other end and output capacitance C ₂be connected, output capacitance C ₂for the input of output circuit, power switch transistor V _tgrid be control input end, power switch transistor V _ttransmitting very current feedback terminal;

The effect of described control circuit 3 produces actual electric current and voltage value by the feedback of two close cycles to produce control signal through pwm circuit compared with set point voltage, control the duty ratio of power device, reach the effect of stable welding line, control circuit 3 comprises pwm circuit, PID control circuit, Hall current sensor T _aand T _b, in control circuit 3, pwm circuit is connected with PID control circuit, PID control circuit and Hall current sensor T _aoutput I _swith Hall current sensor T _boutput I _obe connected, PID control circuit is connected with setting value circuit, and the output of pwm circuit is the output of control circuit 3, and the input of PID control circuit is the input of control circuit 3, Hall current sensor circuit T _aoutput be the current input terminal of control circuit 3, Hall current sensor circuit T _boutput be the overcurrent protection end of control circuit 3;

Described output circuit 4 is by overcurrent protection resistance R _x, choke induction L _x, fly-wheel diode V _x, load variable resistor composition R, overcurrent protection resistance R _xwith fly-wheel diode V _x, choke induction L _xseries connection, choke induction L _xwith fly-wheel diode V _xbe in parallel, overcurrent protection resistance R _xinput be the input of output circuit 4;

The output of boosting current rectifying and wave filtering circuit 1 is connected with the input of Cuk main circuit 2, the control input end of Cuk main circuit 2 is connected with the output of control circuit 3, the output of Cuk main circuit 2 is connected with the input of output circuit 4, and the input of control circuit 3 is connected with the output of output circuit 4.

Control circuit 3 operation principle is as follows:

PID control circuit is made up of three parts: output voltage obtains real output value through sample circuit, this voltage can correct as the actual value of PID adjuster and set point, last being delivered in pwm circuit by PID control circuit output control signal again adjusts pulsewidth, this also forms conventional Voltage Feedback, i.e. outer voltage.

Power switch transistor V in Cuk main circuit 2 _tsource electrode and Hall current sensor T _aseries connection, Hall current sensor T _awill by tested size of current, select suitable no-load voltage ratio current signal to be changed into voltage signal to output in PID controller circuit and compare with set point and correct, once detect and depart from set point, current sense comparator will make PWM latch reset, gate drive signal will export pulse to power switch pipe and regulate, before output sampled voltage error occurs, the pulse of pwm circuit exports and just has regulating action, what feedforward compensation circuit detected is disturbance itself, as long as the change that occurs utility grid voltage, will synchronously carry out detecting and compensating at once, so just transient voltage error can be reduced to minimum, form current feedback inner ring.

These two feedbacks are added in end in the same way and the backward end of the internal comparator of described pwm circuit respectively, constitute two close cycles, reach the effect compensating and export.

Excessive surge current affects Circuits System and normally works, and causes very large impact to circuit and device, therefore, must design current-limiting apparatus and add restriction to it.Hall current sensor T is adopted in the design _bcarry out over-current detection, its operation principle is: when Hall current sensor is greater than set point at the current value that load outputs detects, output signal forces pwm signal to be 0, thus shutdown switch element makes electric current no longer rise.This method current limliting is accurate, effectively can prevent short circuit, overcurrent protection easy to implement.

Pwm circuit produces a control signal by error amplifier, it acts on PWM comparator, a pwm signal is produced after the sawtooth waveforms that the amplitude produced with the oscillator of control chip inside is fixed compares, this road pwm signal again through with the effect of clock pulse after produce the adjustable pwm signal of the duty ratio that is finally used for controlling power switch pipe, therefore the realization that described pwm circuit regulates automatically is realize by feedback and error amplifier completely, when load current reduces or DC input voitage raises, capital causes the rising of output voltage, at this moment the feedback voltage of system increases, control signal reduces, the pulsewidth exported is made to narrow thus output voltage is reduced.

The content that this specification is not described in detail such as transformer boost circuit, current rectifying and wave filtering circuit, PID controller circuit, Hall current sensor circuit and pwm circuit in embodiment belong to the known prior art of this professional domain professional and technical personnel.

Claims (6)

1. adopt an electron beam welding electromechanical source high voltage stabilizing method for micro-ripple Cuk formula converter, it is characterized in that, comprise the steps:

1) three-phase alternating-current supply is after boosting, rectification, filtering, obtains high tension voltage;

2) high tension voltage is through DC converter, adjusts output voltage by the break-make duty ratio of control switch device;

3) output voltage passing ratio integral differential rate of change controller (Proportional-Integral-Differential Controller, be called for short PID) outer voltage and current inner loop and overcurrent protection feedback, and compare with set point, the voltage of the error relatively drawn as control signal through pulse-width modulation (Pulse Width Modulation, be called for short PWM) circuit, by controlling the duty ratio of power device, the size of output voltage can be adjusted;

4) the minimum high voltage stabilizing output voltage of ripple is obtained at output capacitance place.

2. method according to claim 1, is characterized in that, step 2) in DC converter be Cuk circuit:

Cuk circuit comprises input inductance L ₁with outputting inductance L ₂, two inductance L ₁, L ₂between intercouple, as switching tube V _tduring conducting, inductance L ₁in electric current linear growth, electric capacity C ₁pass through V _tand L ₂form discharge loop, diode V _dbe in reverse-biased, inductance L ₁and L ₂between coefficient of mutual inductance be M, following formula of can deriving

U in formula _ithe input voltage of Cuk circuit, di ₁/ dt is input inductance L ₁current changing rate, di ₂/ dt is outputting inductance L ₂current changing rate, M is coefficient of mutual inductance;

Can be obtained by formula (1)

U in formula _ithe input voltage of Cuk circuit, di ₁/ dt is input inductance L ₁current changing rate, di ₂/ dt is outputting inductance L ₂current changing rate, M is coefficient of mutual inductance;

Order

Then formula (2) is reduced to

U in formula _ibe the input voltage of Cuk circuit, M is coefficient of mutual inductance, di ₁/ dt is input inductance L ₁current changing rate, di ₂/ dt is outputting inductance L ₂current changing rate;

Obviously, L is strengthened _1eqand L _2eqnumerical value just can reduce L ₁or L ₂in ripple current, if meet L in circuit ₁=L ₂=M, now in Cuk circuit, input ripple current and output ripple electric current can reduce to zero, but because magnetic device is because of design and processing, component couples COEFFICIENT K is always less than 1;

For analyzing K to the impact of circuit ripple, L can be established ₁and L ₂turns ratio then L _1eqand L _2eqexpression formula become

In formula, K is the coupling coefficient of element;

From formula (4), as nK=1, L ₁input ripple current is zero ripple current, as K=n, and L ₂in output ripple electric current be the even zero ripple current requirement of micro-ripple, make input and output electric current level and smooth;

In like manner adopt above-mentioned derivation formula can draw as switching tube V _tturn off, diode V _dl during conducting ₁and L ₂current changing rate di ₁/ dt di ₂/ dt computing formula:

M is coefficient of mutual inductance, U _oit is the output voltage of Cuk circuit;

No matter for switching tube V _dconducting, diode V _dcut-off or switching tube V _tcut-off, diode V _din ON operation situation, for L ₁, L ₂, K and L ₁and L ₂current changing rate di ₁/ dt, di ₂relation between/dt all can be adjusted according to formula (4), realizes the requirement of the micro-ripple of Cuk circuit;

Step 2) in also introduce and inverse lead diode, inversely lead diode to protect power switch pipe for one in parallel on the power switch pipe side of Cuk circuit, prevent reverse breakdown.

3. method according to claim 1, is characterized in that, step 3) middle output voltage is first through over-sampling, starting, overcurrent and overvoltage protection, overheat protector and noise filter circuit, and detection output voltage changes; PID feedback control circuit is made up of three parts: current inner loop, outer voltage and overcurrent protection three part;

Output voltage obtains real output value through sample circuit, this voltage can as the actual value of PID adjuster and and set point compare after correcting action, delivered in pwm circuit by PID control circuit output control signal and adjust pulsewidth, this also forms conventional Voltage Feedback, i.e. outer voltage;

The emitter of Cuk circuit breaker in middle pipe is connected with Hall current sensor, Hall current sensor will by tested size of current, select suitable no-load voltage ratio to be transferred to by current signal to export and change into voltage signal to output in PID control circuit and compare with set point and correct, once voltage deviation set point be detected, current sense comparator will make PWM latch reset, gate drive signal will export pulse to power switch pipe and regulate, before output sampled voltage error occurs, the pulse of pwm circuit exports and just has regulating action, what feedforward compensation circuit detected is disturbance itself, as long as the change that occurs utility grid voltage, will synchronously carry out detecting and compensating at once, so just transient voltage error can be reduced to minimum, form current feedback inner ring,

These two feedbacks finally change into control signal and deliver to described pwm circuit, constitute voltage and current double closed-loop structure, reach and compensate the stable effect exported;

Excessive surge current affects Circuits System and normally works, very large impact is caused to circuit and device, therefore, current-limiting apparatus must be designed restriction is added to it, Hall current sensor is adopted to carry out over-current detection in the present invention, its operation principle is: when Hall current sensor is greater than set point at the current value that load outputs detects, output signal forces pwm signal to be 0, thus shutdown switch element makes electric current no longer rise, this method current limliting is accurate, effectively can prevent short circuit, overcurrent protection easy to implement;

Pwm circuit produces a control signal by error amplifier, it acts on PWM comparator, the sawtooth waveforms that the amplitude produced with control chip internal oscillator is fixed compares generation pwm signal, this road pwm signal again through with the effect of clock pulse after produce the adjustable pwm signal of the duty ratio that is finally used for controlling power switch pipe, therefore the realization that described pwm circuit regulates automatically is realize by feedback and error amplifier completely, when load current reduces or DC input voitage raises, capital causes the rising of output voltage, at this moment the feedback voltage of system increases, control signal reduces, the pulsewidth exported is made to narrow thus output voltage is reduced.

4. adopt an electron beam welding electromechanical source high voltage stabilizing device for micro-ripple Cuk formula converter, it is characterized in that, comprise boosting current rectifying and wave filtering circuit, Cuk main circuit, control circuit, output circuit;

The effect of described boosting current rectifying and wave filtering circuit obtains level and smooth high tension voltage;

Power conversion, pressure regulation are carried out in the effect of described Cuk main circuit, can also play the effect suppressing current pulsation ripple;

The effect of described control circuit produces actual electric current and voltage value by the feedback of two close cycles to produce control signal through pwm circuit compared with set point voltage, controls the duty ratio of power device, reaches the effect of stable welding line;

The output of boosting current rectifying and wave filtering circuit is connected with the input of Cuk main circuit, the control input end of Cuk main circuit is connected with the output of control circuit, the control input end of Cuk main circuit is connected with the output of control circuit, the output of Cuk main circuit is connected with the input of output circuit, and the input of control circuit is connected with the output of output circuit.

5. device according to claim 4, it is characterized in that, described Cuk main circuit comprises input inductance and outputting inductance, intercouple between inductance, input and output capacitors, output diode and power switch transistor and inversely lead diode, input inductance and input capacitance and power switch transistor, be connected against leading diode common port, one end of outputting inductance is connected with the common port of input capacitance output diode, the other end is connected with output capacitance, output capacitance is the output of output circuit, the grid of power switch transistor is control input end, the transmitting very current feedback terminal of power switch transistor.

6. device according to claim 4, it is characterized in that, described control circuit comprises pwm circuit, PID control circuit, two Hall current sensor circuit, in control circuit, pwm circuit is connected with PID control circuit, PID control circuit is connected with two Hall current sensor circuit, the output of pwm circuit is the output of control circuit, the input of PID control circuit is the input of control circuit, the output of two Hall current sensor circuit is respectively current input terminal and the overcurrent protection end of control circuit, PID control circuit is connected with setting value circuit simultaneously.