Inverter job principle
 

Use shock implement principle, turn into dc first the pulse alternating current that size changes along with time, via lying between heft of dc of lineal all take out, reservation is handed in change heft, repass shift system (step up or step-down) commutation, plastic reachs stabilized voltage, with respect to the alternating current that got according with us needing. Use oscillating circuit to produce the pulsatile dc electricity of certain frequency, reoccupy transformer changes this electric current the alternating voltage that is need. Three-phase inverter produces each other to need the three-phase alternating voltage of 120 degrees of phase angle at the same time.
 

Inverter has a lot of parts to comprise, among them most the part of core is an oscillator. The earliest oscillator is electromagnetism model, development is an electron later model, arrive from discrete element special integrated circuit, control to microcomputer again, more and more perfect, the function of inverter is stronger and stronger also, received very wide application in each domains.
 

Simple inverter circuit
 

This inverter uses transistor of power field effect to regard inverter as device. With car batteries power supply. Accordingly, in the input voltage is dc of 12 bend over. Outputting voltage is the alternating current of 100V. But, input and output voltage are not confined to this. You can use any tension. They rely on transformer to use. Undee output is square wave. According to experience, this circuit restricts 100W power.

 

Circuit must press outfit fuse, when because of overmuch input electric current flows, the oscillator stops.

 

 

Inverter principle circuit: Turn 12V dc into 220V alternating current
 

Compare change of 220V alternating current for 24V, 36V, 48V simple, need to use the principle of transformer only. Electromagnetism mutual inductance, can obtain different voltage.

 

 

Setting closed circuit is v/LIT all over the ground coil of a N, and cross every flux of v/LIT all over the ground coil metabolic rate is same, be equivalent to N at this moment odd v/LIT all over the ground coil establishs ties and become, accordingly inductive electromotive force turns into

 

 

The basis is formulary and knowable, e is electromotive force, namely voltage. Because

 

 

Changeless, want iron piece only the coil amount N of two end is different the result that can achieve transformation.

 

Want alternating current change to add diode to be able to achieve the result of need only for dc, diode is a kind of unit that has two electrode, allow electric current to had flowed by single way only, a lot of use is the function that uses its commutate. Next recycle transformer principle can transform 220V alternating current 12V dc, and the 5V dc of charger of our mobile phone outputs voltage.

 

 

So how to change 12V direct current into 220V alternating current? Above all we will understand inverter, what is inverter?
 

Inverter is a dc electric energy (storage battery of batteries, harbour) change becomes alternating current (it is 220V commonly, 50Hz sine wave) . It is comprised by logic of inversion bridge, control and filter wave circuit. It is the transformer of a kind of DC To AC, it actually with converter the process that is inversion of a kind of voltage. Converter is the 12V dc output that is the alternating voltage change of electrified wire netting stability, and inverter is the 12V volts d.c. that outputs Adapter change is high frequency high pressure alternating current.

 

Next the circuit picture that we see whole process: 12V dc → is high frequency →220V of inversion of bridge of inversion of → of dc of →220V of complete bridge commutate communicates → of dc of step up →220V

 

 

Inversion of high frequency step up dominates circuit:
 

 

(1) the inphase input of the first group of amplifier carries the foot, detect output electric current, with 3 0.33R resistor cent is pressed, when electric current is too big, the voltage on cent pressing resistor exceeds (2) the base is standard voltage, (3) end of crural amplifier output outputs tall n, (3) when the foot is tall n, circuit enters protective state. (2) the foot is comparator input end instead, receive (14) the base is standard, make the referenced voltage of comparator, the control signal that exterior input carries is importable to the foot (4) end time dominates end (also call dead band time control) , with the foot (1) , (2) , (15) , (16) the input end of error amplifier, its input end points touch filling voltage to be 120mV, its can restrict output to end time comes the least value, 4% what be time of cycle of original and toothed wave about. When the output model when 13 feet controls termination land, can obtain cycle of 96% the biggest jobs, and when (13) the foot is received when making referenced voltage, can obtain cycle of 48% the biggest jobs. If we end in the 4th foot,time control input carries set a fixed voltage, its limits comes by 0V between 3.3V, additional end time appears on output certainly. (5) , (6) the circuit of pulse width modulation that the foot is a fixed frequency, inside buy oscillator of linear and toothed wave, oscillation frequency can be passed external a resistor and a capacitance undertake modulatory, its oscillation frequency is as follows:

 

The width that outputs pulse is the positive electrode sex that goes up through capacitance CT toothed wave voltage and signal of additionally two control undertake comparative will come true. Power efferent Q1 and Q2 are controlled at or blame door. The ability when the clock signal when double firm trigger is low n can be chosen to connect, be more than control in toothed wave voltage only namely just can be chosen connect during signal. When control signal increases, the width that outputs pulse will be reduced. (7) end of crural ground connection, (8) , (11) the collector that the foot is Q1 and canal of Q2 in-house switch, power source is received in this circuit, (9) , (10) the foot is Q1, Q2 blast off extremely, make switch be in charge of drive to output end, receive circuit of exterior enlarge of the Q1 in next graphs and Q2. With drive hind extremely push-pull circuit. (12) end of crural power source, (13) the foot dominates end for output, receive (14) the base is standard pulse of two output when voltage differs 180 azimuth, every sendout about the drive push-pull of 200MA or half bridge-type circuit. (15) , foot of the 2nd group of amplifier input end instead, receive fiducial voltage, (16) the foot inputs end in phase, detect power source voltage. Pass when voltage excellent over- (15) when crural reference voltage, (3) the foot outputs tall n, circuit enters protective state.

 

Circuit of inversion of high frequency step up reachs rectification:
 

 

This is develop of type of a push-pull attacks inversion circuit, when drive of E1 drive pulse, q1 guides, make VT3, VT6 guides, VT7, VT8 ends, right now circuit undertakes half weeks of undee enlarge, transformer step up arrives sub, be in charge of rectification through high frequency commutate, when E2 pulse drive, q2 guides, drive VT7, VT8 guides. VT3, VT6 ends, enter so that lose half weeks of undee enlarge. After step up of classics step-up transformer, high frequency commutate.

(this VT38 with circuit of push-pull means consist in in, each are in charge of losing half weeks undee enlarge job, when circuit works, two symmetrical power switch canals have one to be connected to guiding only every time, guide so a loss little efficiency is tall. Push-pull is outputted already can to laden fill electric current. )
 

Inversion bridge inversion:
 

 

 

By the contact outside the 5 feet of TL494CN chip look C3 is mixed finally resistor R15 is received to decide arteries and veins outside 6 feet broadband rate is F=1.1÷ (0.1×220) job of KHZ=50HZ control Q10, Q11, Q13, Q14 is below the frequency of 50HZ, it is 220V dc inversion the alternating current of 220V/50HZ, the graph will fulfil this part function on.

TL494 to when, IC2 controls Q3 to be saturated on-state, q4 is off-state, because Q3 is saturated on-state, criterion Q10 is saturated on-state. Because Q4 is in off-state, q11 is not had because of grid bias voltage and be in off-state, at the same time Q14 is not had because of grid bias voltage and be in off-state, q13 is saturated on-state. Right now 220V dc arrives via electrical outlet of VT6 edge XAC laden again classics VT10 ground connection, form half-period electric current; Retrorse when, IC2 controls Q3 to be off-state, q4 is saturated on-state, because Q3 is off-state, criterion Q10, Q13 is not had because of grid bias voltage and be in off-state, because Q4 is saturated on-state, q11 is in saturated on-state, at the same time Q14 is in saturated on-state, q11 is not had because of grid bias voltage and be in off-state. Right now 220V dc arrives via electrical outlet of VT9 edge XAC laden again classics VT7 ground connection, form negative half-period electric current; Such receiving 220V dc successful transition is output of 220V/50HZ alternating current to be used for load.

 

Circuit protects circuit mediumly:
 

 

Double carry is used to put in circuit compare amplifier LM358 to control output to shed protection too, output voltage crosses low protection circuit, TL431 is set here make 2.5V fiducial voltage, to comparator inphase input carries referenced voltage, the inphase input termination that the first group of carry put outputs electric current to detect, input termination reference voltage instead, pass when electric current big, comparator input voltage is elevatory, when exceeding 2.5V, output end outputs tall n, send the 3 feet of IC1, IC shuts output. The 2nd group of carry put voltage of reference of inphase input termination, input termination to output voltage instead, pass when voltage low, detect the voltage after cent is pressed is low at 2.5V, output end outputs tall n, q1 guides, buzzer calls the police.