Analysis of test of oscillograph power source basically realizes use oscillograph to be opposite power source (switch power source) have relevant test, raise power source to develop the work efficiency of personnel, go to the lavatory to have a test to power source module. Basically involve switch power supply (AC/DC) concerns a test. In most modern system, structure of popular DC power source is switch power source (SMPS) , this kind of power source because can efficient processing load changes and famed.

 

The method of power source signal of typical SMPS includes passive component, active component and magnetic component. SMPS utmost ground decreased to have the use amount of the component of loss, be like resistor and linear mode transistor, the key is used (fall in ideal condition) the component that does not have loss, be like switch type transistor, capacitor and magnetic component. If the graph is shown 1 times,its basically are formed.

 

Graph graph of principle of 1 switch power source

 

The test parameter of switch power source basically includes an input to carry analysis, output to carry analysis of road of analysis of parts of an apparatus of analysis, magnetic cell analysis, switch, modulation analysis, annulus to wait, after following watches check an interface to enter power source to analyse, to checking test project of the function individually. Above all we are with the commonnest switch loss test first exemple undertake explaining.

 

 

One switch loss checks

 

1, test principle

 

The switch parts of an apparatus of switch power source always is the job is in open or close position, can provide taller efficiency. Below good case, switch parts of an apparatus is opened and be being shut do not have loss. If pursue,2 are shown.

 

ON = guides completely (the V = 0 below good case, mean switch loss P = V X I = 0)

 

OFF = is shut completely (the I = 0 below good case, mean switch loss P = V X I = 0)

 

Graph parts of an apparatus of 2 ideal switch

 

But in feasibility condition, putting power loss. Basically include switch loss, conduct loss. Following graphs are shown 3 times.

 

Graph 3 actual loss

 

In the light of power loss main computation basically includes 3 parts the sum:

 

Guide a process loss + shut process loss + guide a loss

 

Ploss=Pon+Poff+Pcond

 

2, test measure

 

Following graphs show the wiring sketch map that switch component analyses 4 times. Among them probe of voltage of poor cent of 1 use high pressure receives the channel the two end of switch, probe of 2 use electric current receives the channel the one aspect of the matter of switch

 

Graph sketch map of wiring of 4 switch component

 

Adjust after the probe rate of probe of good electric current and voltage probe, click [Analyze] enter power source to analyse test interface, in [function] in choice [switch loss] click [parameter is configured] enter parameter to install an interface, following graphs are shown 5 times. Parameter setting is used at deciding the condition of switch, the parameter that need undertakes installing has voltage passageway, electric current passageway, referenced voltage, reference electric current and guide a computational choice.

 

Graph setting of parameter of 5 switch loss

 

Computational result form is shown 6 times like the graph.

 

Graph 6 switch loss measures an outcome

 

● is worth currently: This eventuate is current the computational result of example.

Peace of the ● maximum, least value all is worth: Statistical result, can use Clear to undertake keeping clear of and begin statistic afresh.

● power is the greatest statistic (P) : Instantaneous power maximum.

● energy is the biggest statistic (E) : With the energy of instantaneous power correspondence, interval of a sampling is between meantime.

Statistic of ● power average (P) : Whole sample book is average power.

 

Some engineers can ask, is so much power worth me to basically consult which value? Small writing a proposal is be referenced value with current value.

 

Graph 7 Dv/dt or Di/dt effect pursue

 

Among them: Yellow is Dv/dt, green is Di/dt.

 

Referenced voltage —— is used identify on-state. When the referenced voltage per cent that is less than undee the biggest voltage when voltage value, think this condition is on-state.

 

—— of referenced electric current is used identify close position. When the referenced per cent that is less than undee the biggest electric current when voltaic value, think this condition is close position.

 

General setting is referenced voltage and referenced electric current acquiescent value is OK.

 

2 annulus road is analysed

 

The annulus road of ring switch power source is analysed, the gain that can survey a system, phasic the curve that changes along with frequency (Bai Detu) , analyse gain surplus of the system and phasic surplus, in order to decide systematic stability; In the impedance analysis of passive parts of an apparatus, annulus road analysis can observe the curve of high frequency impedance of capacitance, inductance, measure capacitance ESR to wait. A when annulus road analyses main effect analyses the stability of switch power source namely.

 

1, test principle

 

Sweep test principle basically is the sine signal that gives infuse of circuit of switch power source change of a frequency, those who measure switch power source to go up in frequency domain is characteristic, pass through through the analysis abundant of frequency, gain is spent and phasic abundant is spent will judge annulus road to whether be stabilized, the control circuit that can design stability for electronic engineer provides direct data. Additional, annulus road analysis also has Chan Pin to nod test function. The measurement that uses Baidetuke to leave systematic gain in order to see in different frequency and phasic, if pursue,8 are shown.

 

Graph Baidetu and 8 relevant parameter

 

Parameter has related Bai Detu:

 

● passes through frequency: Gain is the corresponding frequency when 0dB;

● phasic abundant spends: Gain is the corresponding phasic difference when 0dB;

● gain abundant spends: Phasic the corresponding gain when be 0° is poor.

 

Systematic stability can carry the phasic surplus in Baidetu, gain surplus, pass through frequency will measure.

 

During the system is developed, personnel of research and development can use the design that annulus road circuit undertakes above Saber of system simulation software, PSIM, Simplis and simulation in development earlier stage, what developing is medium later period, the test and verify that the annulus means that can use ZDS3000/4000 series oscilloscope analyses a function to have character of real annulus road circuit and improve.

 

2, test measure

 

Switch power source is one included negative feedback operating ring actually the amplifier of the road, meeting enlarge communicates signal and make feedback answer to laden change. Answer a test to complete operating ring journey, need disturbs signal (the signal of sweep sine wave of certain extent and frequency limits or signal of wave of sine of onefold frequency dot) infuse arrives in the feedback method of operating ring road. This feedback method points to the network of resistor voltage divider of R1 and R2 namely. We need the infuse resistance with a very little value of a block to thrust feedback annulus way in, ability infuse disturbs signal.

 

Issue the infuse resistance that the graph shows 9 times to be 5Ω for example, it is negligible that infuse resistor and R1 and photograph of impedance of R2 series connection are compared. So, the user can consider a resistor of infuse of value of this low block to regard the test that uses for a long time as parts of an apparatus. Still need to use transformer of a segregation to keep apart this communication to disturb signal additionally, do not arise thereby any dc slants buy. Because the voltage of actual infuse and output is general very small, because this signal infuse carries a proposal to use BNC head to turn,the wire cable of clincher undertakes signal infuse, and use the signal that the probe of X1 undertakes infuse end and feedback are carried measure.

 

When the synchronous annulus road of annulus road function checks, need uses the signal that sends road of far electron annulus to check form a complete set to produce module and ZDS3000/4000 series oscillograph to be linked together, through oscillograph control signal happening module cooperates to generate the frequency signal of need, if the graph is shown 9 times,annulus road checks signal hookup.

 

Graph 9 annulus road checks signal wiring

 

If the graph is shown 10 times,the objective link that synchronous annulus road checks pursues, make in this graph of back of series of ZDS3000/4000 of join of cable of wire of a BNC spark output end and signal produce module, the cable of wire of output reoccupy BNC of signal happening module receives segregation transformer repeatedly, the output that keeps apart transformer turns through BNC the wire cable of clincher, go to signal infuse to be measured board infuse resistor two end, compare the probe that is X1 with two attenuation next, measure infuse end and the signal that output end.

 

Graph 10 annulus road checks objective link

 

3, parameter setting

 

Click oscillograph face plate to go up [Analyze] key, click again [annulus road checks] pushbutton, enter annulus road to check functional menu. Click [parameter is installed] pushbutton, can play a parameter to install the window, rotate knob A can choose parameter, short after pressing knob A, can undertake parameter is revised, include among them [parameter is installed] , [filter wave is installed] and [synchronous setting] . If the graph shows 11 times:

 

Graph 11 parameter set bill of fare

 

Of annulus road function run what can click menu [move stop] after the test is started, the interface is met the interface that switch runs to annulus road sweep, the frequency that the function can go to according to current sampling, phasic difference, gain, ceaselessly scale gives frequency and the dynamic curve of phasic, frequency and gain, among them, blue curve is gain trace, orange curve is phasic curve. If the graph shows 12 times:

 

Graph 12 sweep test moves in

 

4, the interface explains

 

Road of ZDS3000/4000 series annulus analyses a function to have distinctive sweep to analyse operation interface, undertook to checking operation and user experience sexual ground is designed innovating, if the graph shows 13 times:

 

Graph 13 annulus road checks sweep interface

 

The bag contains following section:

 

Active area of ● sweep weaveform: Blue curve is gain trace, orange curve is phasic curve, PM/GM information shows in top right corner, can undertake rolling examining every measurement point through knob B, can magnify show;

● quick operation feels pushbutton region: This area has button of a quick operation, feeling clicks an operation, can be record in calibration parameter for example, can the indication means of switch gain and phasic curve;

● gain is phasic and perpendicular scale: Show the perpendicular scale of current gain trace and phasic curve, in sweep moving process, the function will be self-adjusting perpendicular scale, show range in order to satisfy metabolic curve. After sweep ends, the user is OK him hand is moved modify perpendicular file with limits.

● stores the passageway operates area: The function is supportable memory 8 groups of sweep curves before, convenient undertake checking the contrast between. Can undertake indication concealing to passageway of every groups of memory, heavy command, guide derive wait for an operation.

 

5, result analysis

 

Cross sweep curve Bai Detu, see the gain inside whole frequency limits and phasic change trend OK and intuitionisticly, go to the lavatory to observe and be analysed, accomplish know fairly well. The sweep curve of actual measurement power source is shown 13 times like the graph, gain abundant is measured (GM) measure with phasic abundant (PM) information shows the top right corner in sweep interface, phasic abundant is spent (PM) it is to show gain passes through the phasic value when 0dB, gain abundant is spent (GM) it is to point to phasic pass through the gain value of 0° . PM and GM are a when measure stability of switch power source main index.

The article is reprinted from science and technology of ZLG make contributions.