CN201163292Y - Electric power engineering high-voltage resistor load implemented by phase-shifting control full-bridge converting circuit - Google Patents

Abstract

The utility model relates to a high voltage resistive load for measuring the voltage stabilization precision and current stabilization precision of a charger to be tested in the power engineering. The measurement is realized through a phase shift control full bridge transfer circuit. The load comprising a vacuum resistance tube is provided with a load controller which is a phase shift control full bridge type zero voltage switch-pulse modulation transfer circuit and particularly a UC3875 control chip. Two groups of vacuum resistances are respectively connected with the load controller, wherein one group of vacuum resistance is a fixed vacuum resistance assembly R2, the other group is a vacuum resistance assembly R1 controlled by a relay assembly DL2, and a DC voltage is applied to the two groups of resistances. The load controller is connected with a programmable controller through an I/O control interface and is also connected with the testing device of the charger to be tested through a computer CPU. The load controller forms a closed loop system with the charger to be tested after D/A conversion so as to realize computer full-process control. The resistive load which can realize full-range seamless regulation is continuously variable in the full range of 0-300V and 0-30A, with high efficiency, small size, light weight, and simple and convenient assembly and maintenance.

Description

The power engineering high-tension resistive load that the phase shifting control full-bridge circuit is realized

Affiliated technical field

The utility model relates to a kind of electric elements---resistance, particularly relates to the precision of voltage regulation of measuring tested charging set in the power engineering, the high-tension resistive load of precision of steady current test.

Background technology

Along with the develop rapidly of nation-building, more and more higher to the measurement requirement of tested charging set in the power engineering.More or less there is deficiency in the load of existing power engineering high-tension resistive, and traditional rheochord is regulated resistance can not realize program control conciliation; Utilizing semiconductor devices is that volume is big as the shortcoming of heater element, heaviness; Adopt the ohmic load of fixed resistance permutation and combination method can not change resistance continuously.The ceramic PTC DC load of development in recent years, though have advantages such as low cost of manufacture, control technology be simple, but after the PTC element applies voltage, because of the self-heating function of itself, after the interior heat that is produced and outer heat reach balance, though the change curtage, and himself or environment temperature do not change, its resistance is constant, output current is adjusted in 0～100%In scope continuously changed and can't realize.Simultaneously ceramic TPC is subject to the influence of environment for use (as temperature, wind-force), and TPC brings bigger difficulty because of material composition and purity, sintering process etc. can cause each batch products property difference very big to maintain and replace.So these loads all can not be satisfied growing power engineering construction, especially the DC voltage-stabilizing of high-acruracy survey charging set, the ohmic load of direct current current stabilization are needed.

The utility model content

The purpose of this utility model provides a kind of high-tension resistive load that is used to measure, and this load volume is little, in light weight, and the gamut that can realize 0～50A realizes continuous program controlled variable, and efficient height, good reliability.

The purpose of this utility model reaches like this: the power engineering high-tension resistive load that a kind of phase shifting control full-bridge circuit is realized, be connected with the detection system of tested charging set, the high-tension resistive load, the detection system of tested charging set and tested charging set form and detect the loop, contain the vacuum resistance pipe, it is characterized in that: be provided with load controller, load controller is phase shifting control bridge-type zero voltage switch-pulsed modulation translation circuit, on load controller, connect two groups of vacuum resistances respectively, one group is fixing vacuum resistance R2, another group is the vacuum resistance combination R1 of relay group DL2 control, and DC voltage is added on two groups of resistance.

Load controller is provided with the I/O control interface, be connected with Programmable Logic Controller by the I/O control interface, Programmable Logic Controller is connected with computer CPU, computer CPU also is connected with the pick-up unit of tested charging set, after the D/A conversion, constitute closed-loop system with tested charging set, by display screen system is monitored, load controller is carried out programmed control by computer keyboard, and the storage data.

Phase shifting control bridge-type zero voltage switch-pulsed modulation translation circuit is the UC3875 control chip.

Vacuum resistance is an alloy silk vacuum resistance pipe, and vacuum resistance combination R1 is by some vacuum resistance pipe parallel resistor combinations.

Before direct supply is input to load controller and resistance, add isolating switch.

Good effect of the present utility model is: the program control load of adjustable high pressure adopts phase shifting control full-bridge circuit pulse modulation technology to reach the seamless adjusting of program control ohmic load gamut, makes program control ohmic load realize 0～300V, the gamut continuous variable of 0～30A.Be furnished with extendible fixed resistance load,, realize the gamut follow-on test of 0～50A according to the quantity or the resistance value of test needs transformation resistance pipe.Efficient height, volume are little, in light weight, and installation and maintenance are convenient, and be simple.

Description of drawings

Fig. 1 is the structural representation of the utility model high-tension resistive.

Fig. 2 is the control section circuit diagram of the utility model controller.

Fig. 3 is the UC3875 control chip inner structure block scheme that the utility model controller adopts.

Fig. 4 is the ohmic load control waveform figure of the phase shifting control full-bridge circuit of the utility model employing.

Embodiment

Accompanying drawing has provided a specific embodiment of the present utility model.

Referring to accompanying drawing.Connect two groups of vacuum resistances on load controller respectively, R1 is the resistance combination that the vacuum resistance pipe is formed.This routine R1 is by RA=30 Ω, RB=30 Ω, and RC=30 Ω, RD=30 Ω, RE=30 Ω, RF=30 Ω, RG=75 Ω, RH=140 Ω, RI=270 Ω series resistance is formed.Change resistance value by the combination in parallel of the above-mentioned series resistance of relay group DL2 control break.R2 is a fixing vacuum resistance, the R2=30 Ω that this is routine.By changing the R2 terminal voltage, change power.Connect R1, R2 on load controller, just can pass through R1, the combination of R2 resistance realizes that electric current 0-50A regulates continuously.

Load controller is provided with the I/O control interface, be connected with Programmable Logic Controller by the I/O control interface, Programmable Logic Controller is connected with computer CPU, computer CPU also is connected with the pick-up unit of tested charging set, after the D/A conversion, constitute closed-loop system with tested charging set, by display screen program control load controller is monitored, load controller is carried out programmed control by computer keyboard, and the storage data.

Under traditional condition that the full-bridge circuit on-off element is very high at voltage or electric current is very big, open or turn-off under the control of gate pole, voltage, electric current are all non-vanishing in the switching process, occur overlappingly, have caused switching loss.Switching loss increases with switching frequency and sharply rises, and circuit efficiency is descended, and has hindered the raising of switching frequency.

On the phase shifting control technical foundation, the leakage inductance of utilizing the output capacitance of power tube and output transformer makes the conducting under no-voltage successively of four switching tubes of full-bridge converter as resonant element, realizes the soft switch of constant frequency.Owing to reduced the switching process loss, conversion efficiency can reach 80%-90%, and it is excessive can not switch stress to take place.So select phase shifting control bridge-type zero voltage switch width modulation (PSC FB ZVS-PWM) translation circuit for use.The special chip UC3875 control chip that has adopted U.S. UNITRODE company to release in this example at the phase shifting control scheme.Usually use UC3875 work rate Switching Power Supply, output voltage is fixed and in low voltage value, load variations.In the utility model, the high voltage switch power supply is done with UC3875 in innovation ground, and working method is the phase-shifting resonance full-bridge soft-switching.Input DC180V-300V, output resistance 30 Ω, output 0-200V, maximum current 7A.

The UC3875 chip can carry out phase shifts to the phase place of full-bridge switch, realizes fixed pulse width modulation controlled frequently, and the inner structure block scheme of UC3875 chip as shown in Figure 3.

1 pin output+5V reference voltage can be used as the power supply of other elements of inside or external circuit.2 pin when drawing the output signal height to certain value, make C output with A output anti-phase by inner rest-set flip-flop and gate circuit effect as the Voltage Feedback control end, i.e. A, C output signal phase shift 180 spent; Equally, when pin 2 output signals are lower than 1V, make C output and A output homophase, i.e. A, C output signal phase shift 0 degree by inner rest-set flip-flop and gate circuit effect.As seen can control phase place variation between 0 ~ 180 degree between A, C by the output of control pin 2 ends.The principle of work of B, D is similar to A, C.3 pin utilize divider resistance to detect output supply voltage as the inverting input of error amplifier usually.4 pin link to each other with 1 pin reference voltage as the in-phase input end of error amplifier, detect the output supply voltage of 3 pin.5 pin are as the current detecting end, and its benchmark is set to internal fixation 2.5V (by dividing potential drop), and output is turned off when voltage surpasses 2.5V, and soft start 6 pin presets can be realized overcurrent protection.7 pin and 15 pin are as the output delay control end, by the electric current of this pin between over the ground is set the dead band are set, and are added between the same brachium pontis two pipe driving pulses transient time when realizing that no-voltage is opened.8,9,13,14 pin are as output terminal, but driven MOS FET and transformer.10 pin are as power voltage terminal, for output stage provides required power supply.11 pin are as the chip power supply power supply, and for chip internal numeral, artificial circuit part provide power supply, there is undervoltage lockout circuit inside, and it opens threshold value is 10.75V, and closing threshold value is 9.25V.The return difference that 1.5V is arranged between the opening and closing can effectively prevent beating when circuit is worked near threshold voltage, 16 pin need outer meeting resistance and electric capacity that oscillation frequency is set as the frequency configuration end.17 pin provide clock signal as when output; As input, provide synchronous points.18 pin need an external resistance to produce oblique wave as the steepness end.19 pin need external capacitor to ground as the oblique wave end.20 pin are the reference datas of all voltages as signal ground.

The control principle of controller and the course of work are referring to Fig. 2, Fig. 3.INPUT+, INPUT-are the output voltage of charging set power supply; UREF is the control voltage of regulating load power; UOUT+, UOUT-is the output of control voltage.The course of work is: (0～5V) linear voltage is comparing with EA-(pin 3, error amplifier inverting input, the partial pressure value of switch power source output voltage) to the EA+ (pin 4, error amplifier in-phase input end) of UC3875 the UREF of input.When EA+ powers on when being pressed in DC0～5V linear change, change the dutycycle of pulse width modulator, Switching Power Supply output just changes from DC0～200V, because pull-up resistor 30 Ω fix, output current is just in the 0-7A variation, the adjusting fineness has reached 0.1%.

The core of UC3875 is a phase-modulator, and its 13 pin B output signal and 14 pin A output signals are anti-phase, and 9 pin C output signals and 8 pin D output signals are anti-phase, and these four drive signals are removed the driven MOS pipe by driving transformer after expanding stream.Four output terminals that the characteristics of phase control are embodied in UC3875 have identical driving pulse and drive two half-bridges of A/B, C/D respectively, by phase shift dislocation control source time are arranged, and make four switch wheel conductances of full-bridge logical.A dead band is all arranged before each output stage conducting, and can adjust Dead Time.Guarantee the output capacitance discharge off of next device for power switching in time in this dead band, for the switching device that is about to conducting provides voltage to open condition.Therefore, (A/B, can control separately resonant switch action time C/D) every pair of output stage.Under full-bridge transformation topology pattern, the advantage of phase shifting control obtains the embodiment of fullest.UC3875 all can work under voltage mode and current-mode, and has the excess current shutoff to realize the quick protection of fault.

This high-tension resistive has efficient height, little, the lightweight characteristics of volume.Be furnished with extendible fixed resistance load, realize the gamut follow-on test of 0～50A, the effect of controller and effect are very remarkable, can reach:

A. the dutycycle range of control 0～100%.

B. export the turn on delay time programmed controlled.

C. voltage mode is controlled and Controlled in Current Mode and Based.

D. maximum operation frequency 1MHz.

E. the totem pillar drives output circuit, maximum drive current 2A.

F. built-in 10MHz error amplifier.

G. has the under-voltage lock function.

H. starting current is low, only is 150uA.

I. in the under-voltage locking process, output terminal keeps low spot flat.

J. has the soft start control function.

K. excess current comparer locking back all can be restarted in whole work period.

L. built-in accurate 5V reference voltage, fine-tuning.

The control waveform of phase shifting control full-bridge circuit as shown in Figure 4, the advantage of phase shifting control obtains the embodiment of fullest.

Claims (5)

1, the power engineering high-tension resistive load that a kind of phase shifting control full-bridge circuit is realized, be connected with the detection system of tested charging set, the high-tension resistive load, the detection system of tested charging set and tested charging set form and detect the loop, contain the vacuum resistance pipe, it is characterized in that: be provided with load controller, load controller is phase shifting control bridge-type zero voltage switch-pulsed modulation translation circuit, on load controller, connect two groups of vacuum resistances respectively, one group is fixing vacuum resistance R2, another group is the vacuum resistance combination R1 of relay group DL2 control, and DC voltage is added on two groups of resistance.

2, power engineering high-voltage load as claimed in claim 1, it is characterized in that: described high-tension resistive load, the detection system of tested charging set and tested charging set form and detect the loop is that the I/O control interface is set on load controller, be connected with Programmable Logic Controller by the I/O control interface, Programmable Logic Controller is connected with computer CPU, computer CPU also is connected with the pick-up unit of tested charging set, after the D/A conversion, constitute closed loop with tested charging set, by display screen system is monitored, by computer keyboard load controller is carried out programmed control, and the storage data.

3, power engineering high-voltage load as claimed in claim 1 is characterized in that: described phase shifting control bridge-type zero voltage switch-pulsed modulation translation circuit is the UC3875 control chip.

4, power engineering high-voltage load as claimed in claim 1 is characterized in that: before direct supply is input to load controller and resistance, add isolating switch.

5, power engineering high-voltage load as claimed in claim 1 is characterized in that: the vacuum resistance on the described load controller is an alloy silk vacuum resistance pipe, and vacuum resistance combination R1 is by some vacuum resistance pipe parallel resistor combinations.

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