Circuit of half bridge inversion is electronic ballast and electron in energy-saving lamp the most commonly used also be the basiccest circuit, understand its working principle correctly, will conduce to us choosing yuan of parts of an apparatus to be like the magnetism annulus transformer, parameter that controls the element such as the galvanic feeling, capacitance that start reasonably, arrange the drive circuit of dynatron correctly, in order to reduce its power comsumption and quantity of heat, raise the dependability of whole lamp. Regretful ground is to got observation instrument in the past (be like oscillograph) the confine with test method, we cannot observation is like dynatron to dot of the key in circuit the correct weaveform of each electrode electric current (like document the initiative weaveform of the voltaic IB of 4, Ic is wrong) , cannot make the quantitative analysis that accords with actual condition and judgement consequently, down to forms the concept of a few mistakes. See Mr Xie Wenhao of deep love company is published in Chinese lighting electric equipment recently (publish at 4 years 11, 12 period) article, be inspired not less, after company of lighting of general going to Europe, use more advanced oscillograph TDS5000, to the electric current with bit more crucial circuit and voltage weaveform, had careful test, feel to rise somewhat on understanding, clarified concept of not little in the past introduced from the northern and western nationalities or from abroad , special compose the article, cast a brick to attract jade-offer a few commonplace remarks by way of introduction so that others may come up with valuable opinions, with foliaceous gentleman deliberate, advise with domestic square home.

 

The labour principle of circuit of half bridge inversion, although this circuit is well-known, but people understands to it however not very correct, put in a few wrong ideas.

 

If principle of job of circuit of half bridge inversion pursues 1

 

 

Working principle:

① Tl time: Switch K1 guides, k2 ends, voltaic direction is like the ① in the graph, power source gives advocate change T power supply, charge to capacitance C2.

② T2 time: Switch K1, K2 ends, negative cut is passed without electric current (dead band) .

③ T3 time: Switch K1 ends, k2 guides, capacitance C2 discharges to load.

④ T4 time: Switch K1, K2 all ends, form dead band again. Went up to get is like a graph in load repeatedly so the electric current of 2, achieved the goal of inversion.

 

The working principle of IGBT welder

① power source furnishs:

The welder that provides inversion switch with field effect is same, welder power source furnishs by town report, via inverter furnishing after wave of rectification, filter.

 

② inversion:

Because the working electric current of IGBT is big, can use the form of half bridge inversion, serve as switch with IGBT, its are enlightened with shut control by drive signal.

 

The generation of ③ drive signal:

Drive signal still uses wide modulator of processing arteries and veins to output the form of signal. Make of two drive signal phasic and stagger (have dead band) , be connected with preventing two switch canal to guide at the same time and had produced big electric current to damage switch is in charge of. The midpoint of drive signal sinks likewise certain extent, disturb in case make switch canal misdirect is connected.

 

④ protects circuit:

IGBT welder also had been installed stream, press too, overheat protection, some type also have cut to flow, in order to assure welder and person safety, its job principle and welder of field effect canal are similar.

 

Inversion and commutate are two opposite concepts, rectification is a process that alternating current commutation is dc, and inversion makes change direct current the process that is alternating current, the arc solder power source that uses inversion technology calls inversion welder. Inversion process needs parts of an apparatus of high-power electron switch, use the inversion welder that ambipolar transistor IGBT regards insulation bar as switch parts of an apparatus to become IGBT inversion welder.

 

The working process of inversion welder is as follows: three-phase or commutate of alternating current of single-phase labour frequency, via a more flowing dc getting after filter wave, the inversion circuit that comprises by IGBT turns into this dc the alternating current of a few KHZ, classics advocate after transformer step-down, obtain smooth dc output to solder via rectification filter wave again electric current.

 

Advantage of inversion electric welder: Because inversion job frequency is very tall, so advocate the core cut area of transformer and coil circle number decreases greatly, accordingly, inversion welder can save metallic stuff greatly, reduce over all dimension and weight, reduce electric energy loss greatly, more important is, inversion welder can is opposite inside the time of delicate stage output electric current undertakes adjustment, can come true so solder the good control process that process place asks, gain satisfaction solder the effect.

 

The working principle of circuit of half bridge inversion

1, the equivalent circuit of circuit of half bridge inversion:

 

 

2, the working principle of circuit of half bridge inversion: In pursueing on, a, B is midpoint of two half bridge respectively, UAB is the voltage between them, r is equivalent resistor, l sheds inductance to clutch, LC makes circuit of series connection resonance, the square wave of UAB input change is C the approximate sine wave of two end, completed inversion process.

 

3, the application in circuit of typical electron fluorescent lamp:

 

 

The L2 in the graph, C6, RLA, it is circuit of half bridge inversion, tube equivalent resistor is by tube voltage and tube electric current are decided.

 

Left circuit changes direct current set prescription wave (to rise smoothly brace up and continuously oscillation, circuit is more complex) , offer half bridge midpoint by high frequency transformer, comprise passive by C7, C8 half bridge midpoint, came true to arrive by dc the inversion of communication.