One. What is inverter in electric appliance switch factory, www.guofadq.com
The inverter is an electronic device, to an alternating current (AC ) converts DC ( DC ), the converted communication can be in any desired voltage and frequency with the appropriate use of transformer switch, control circuit.
Static inverter with no moving parts, and in the application to use a wide range, from small switch power supply in computer, large power high voltage DC power supply application, transport volume. The inverter is usually used for AC power supply from the DC source, such as solar panels and batteries.
The inverter is a kind of high power electron oscillator. It is so named because early machinery, AC / DC converter work put forward the contrary, therefore is to convert DC to AC.
The inverter performs the opposite function of a rectifier.
The two inverter development history.
2.1 early converter
From late twentieth Century through nineteenth Century, DC to AC power conversion is completed using rotary converter or electric generator (mg sets). In the early twentieth Century vacuum tube and inflatable tube was used in the inverter switching circuit of. The tube is the most extensive thyratron.
Electrical converter 's explanation of the origin of the word inverter. The early AC to DC converter using an induction or synchronous AC motor directly connected to exactly the right moment produced DC generator ( dynamo ) born commutator reversed, so that the generator is connected at its. A later development is the synchronous converter, in which the motor and generator armature winding are combined into one, and one end of the slip ring and the commutator in other areas, only one frame. The result is either with AC, DC output. With 1 mg, DC can be considered a separate AC; and the synchronous converter, in a certain sense, it can be considered a" mechanical rectification ac". Due to a right auxiliary equipment and control equipment, a mg or rotary converters can" run backwards", changed to DC to AC. Therefore, an inverter is an inverted converter.
2.2 controlled rectifier inverter
Since the beginning of the year transistor applications to provide sufficient voltage and current of inverter 's rating, this is in 1957 the introduction of thyristors or silicon controlled rectifier (SCR ) began to transition to solid state inverter circuit.
12 pulse line commutation circuit
The controllable silicon circuit design demand is considered in the thyristor. Silicon controlled rectifier is not closed or automatic door control signal off. They just turn off the forward current drops below the low holding current, silicon controlled rectifier with each process, through some external. The source of controllable silicon is connected to AC power, at each change of naturally occurring reversing the polarity of the voltage source. Silicon controlled rectifier is connected to a DC power source usually need to force change a kind of means, forcing the current to zero commutation is required. The most complex circuit adopts thyristor natural commutation, not forced commutation. With the addition of forced commutation circuit, controllable silicon has been used for the type of inverter circuit.
In the application of the transfer source inverter DC power from the 1 to the AC power supply, it can use the AC to DC converter control mode of the inversion. In the inversion mode, a controlled rectifier rectifier inverter for working line. This operation type, can be used in HVDC transmission system and a regenerative braking system to operate the motor control.
Another type of SCR inverter circuit is a current source inverter input ( CSI ). Deep inverter is a dual six step voltage source inverter. With a current source inverter, DC power supply is configured as a current source, rather than a voltage source. The inverter switching tube uses six step sequential indicator load current waveform as strengthening current 1 three-phase alternating current. CSI inverter rectifying method includes a load capacitor commutation and commutation. Because these two kinds of methods, input current regulation assisted commutation. As the load commutation, the load is a synchronous motor power factor is maintained in leadership.
Since they have become the ratings in the higher voltage and current, such as semiconductor transistor or IGBT signal can open and close control means, has become the preferred switching circuit element inverter use research.
2.3 pulse rectifier and inverter
The rectifier circuit is often massage stroke number current flowing to the DC side of the rectifier input voltage of each cycle. A single phase half wave rectifier is a pulse circuit and single phase full wave rectifier is a two pulse circuit. Three phase half wave rectifier is a three pulse circuit and a three-phase full wave rectifier is a 6 pulse circuit.
Because the three-phase rectifier rectifier, two or more than two, and sometimes in series or parallel to obtain higher voltage or current ratings. The rectifier input, supplied from the supply to the outputs are special transformer. This multiplication method effect. The 6 stage is from the two transformers, 12 stages, from the 3 transformers. Association of the rectifier circuit is a 12 pulse rectifier, 18 pulse rectifier.
When the controlled rectifier circuit in the inversion mode of operation, they will be pulse punch number. Rectifier circuit with a higher number of pulses has been reduced by the AC input current harmonic content, reduce the ripple of output voltage. The inversion mode, the circuit has high pulse number low AC output voltage waveform of the harmonic content.
The three inverter circuit are described.
Simple inverter circuit 1 shows the electrical switch and an automatic equivalent
Automatic switching transistor and a two winding mechanical switch, the installation of automatic transformer split execution device
Square wave and sine wave basic components, the 3 harmonic and five harmonic
3.1 basic design
In a simple inverter circuit, a DC power supply is connected to the primary winding of the transformer through the center tap. A switch rapidly switched back and forth, make the return current to DC power supply ends of the alternative pathway, through the primary winding, and then the other. Alternating direction of the current in the transformer primary windings of the alternating current (AC ) in the two loop.
Mechanical and electrical equipment switch includes two versions of the fixed contact and moving contact spring support. The spring has a fixed contact activities and 1 on the 1 electromagnets pulling the movable contact to the surface of the fixed contact. The electromagnet current interruption under the action of the switch, the switch rapidly back. This type of electrical switch, called a vibrator or buzzer, once in the use of vacuum tube car radio machine. A similar mechanism has been used in the bell, a buzzer and a tattoo gun.
When they become ratings may have enough power, transistors and various other types of semiconductor switches has been incorporated into the inverter circuit design.
The 3.2 output waveform
The transformer is switched to the output of the inverter is simple as described above, when not coupled, generate square wave voltage waveform, because of its simple take-off and natural relative to the sinusoidal waveform is usually the AC power waveform. Using Fourier analysis, regularly send waveform sine wave of sum of infinite series. Sine wave with the same frequency with the original waveform is called a fundamental component. In addition the sine wave, called harmonics, which is comprised of a series of fundamental frequency in a frequency is an integer multiple of.
Waveform of inverter output can be expressed using Fourier analysis data to calculate the total harmonic distortion ( THD ). Harmonic distortion is the most fundamental voltage is the square root of the square sum of harmonic voltage:
The output waveform is formed by an inverter required depends on the quality of the connected load characteristics. Some takes a load of a nearly perfect sine wave voltage supply, in order to work normally. Other loads may be running very well, square wave voltage.
3.3 advanced design
Full bridge inverter circuit with antiparallel diode, a transistor switch and there are many different power supply circuit topology and control strategy used in the design of inverter. The different design method to deal with various problems, may be more or less important depends on the use mode of the inverter.
Waveform quality problems can be solved in many aspects. Capacitors and inductors can be used to filter wave. If the design includes a transformer, filter can be applied to the transformer primary or secondary side or both sides. Application of lowpass filter, so that the fundamental wave component is passed to the output, while restricting the passage of harmonic components. If the inverter high frequency power design provides a fixed, a resonator can be used to. For the adjustable frequency inverter, filter must be tuned to a frequency is the highest root above.
Since most load includes inductors, feedback rectifier or antiparallel diodes are often connected to each semiconductor switch is provided in the path of the perceptual load of the peak current, when the switch is in an open state. In anti-parallel diode is somewhat similar to the freewheeling diode for alternating current / direct current converter circuit.
Analysis display, waveform, such as square wave, which is about 180 degrees at the antisymmetric contains only odd harmonics, third, fifth, seventh and other waveforms, with a certain width and height of the measures to eliminate or" Cancel" additional harmonic. For example, inserted through the square wave between the positive and negative parts Zero voltage step harmonic is divisible by 3, can be eliminated. This allows only five, seven, eleven, thirteen, one of the steps is the width required for each step, and the positive and negative of zero voltage step six in each period of 1/3.
Change the square wave the above example pulse width modulator ( PWM ). Modulating, or regulating pulse width square wave is often used as a method of regulating voltage or adjust the output of the inverter. When the voltage control, is it right? Must, a fixed pulse width can be selected, so as to reduce or eliminate harmonic choice. Harmonic elimination technique is generally applicable minimum harmonic filter is because more effective at low frequency and high frequency ratio. Multiple pulse width or carrier switching frequency and carrier frequency. These control schemes are often the use of variable frequency motor control inverters, because they allow the frequency adjustment range of the output voltage, but also improve the waveform quality.
Multilevel inverter to provide another method to eliminate harmonic. Provides a multilevel inverter output voltage waveform, exhibits some levels in multiple steps. For example, it can generate split rail by allowing more sine wave DC voltage at the two centers of inputs, or positive and negative input and ground. By connecting the railway inverter and the negative output end sequence between the rail and floor front, positive orbit, ground rail and the negative rail, then the two on the railway, ladder waveform is generated at the output of the inverter. This is an example of inverter, a 3 layer: a two voltage and ground.
3.4 phase inverter
3 phase inverter connected load
Three-phase inverter is used in variable frequency drive, such as high power DC power transmission. A basic three-phase inverter consists of three single-phase inverter switch terminals are each connected to a load three. The most basic control scheme, operation of the switch three is coordinated, so that the work of a switch in a basic waveform output for each of the 60 degree point. This creates a line to line output waveform with six steps. The six step step wave, square wave, zero, negative part of the voltage between a positive step harmonic is a multiple of 3 and be eliminated, as described above. When the operator based on the PWM technology is applied in six steps of waveform, the basic overall shape or wave shape, on the retention times, the third harmonic and its cancellation.
3 phase inverter switch circuit display 6 step switching sequence and between the terminal voltage waveform of A and C
In order to construct the higher rated power inverter, a two step 6 three-phase inverter can be connected in parallel with higher current rating or higher voltage class series. In two of these cases, the output waveform of phase shift, to obtain a 12 step waveform. If additional inverter combination, 18 steps and three inverter inverter inverter is usually for the purpose of combining the voltage or current to increase viewership rate, improving the quality of wave.
The 4.5 variable frequency drive
Variable frequency drive control of motor power supply operating speed of AC motor and control of voltage frequency. An inverter to provide controllable force. In most cases, the variable frequency drive includes a rectifier, the DC power supply inverter power source is available from the main AC. Since the inverter is a key component of the variable frequency drive, sometimes referred to as the inverter drive or just inverter.
4.6 electric vehicle drive
Variable speed motor control inverters currently using the power of the traction motor in electric and diesel electric rail vehicles and battery electric vehicles and hybrid electric vehicle in high speed highway, such as the Toyota prius. Frequency conversion technology is being developed specifically for the various improvements in electric vehicle application. Vehicle regenerative braking, generator inverter also need from as a car (now agent ) and its storage battery.
4.7 air conditioning
A transfer machine < bearing inverter tag using variable frequency drive to control the speed of the motor, so that the compressor.
4.8 in general
A transformer allows for converting AC to any desired voltage, but on the same frequency. Converter, coupled with DC rectifier, can be designed to convert any voltage, AC or DC, any other voltage, also AC or DC, in any desired frequency. Power output than input power, but the efficiency high, with residual heat for small power consumption proportion.
4.9 warning
Some low power inverter with a warning not to use traditional fluorescent lighting. This is because the power correction capacitors connected in parallel with the lamp. Delete the capacitor will solve the problem
The application of inverter in four.
4.1 the use of DC power supply
Design of inverter, is provided from the 12 volt DC car source provided in AC 115 v. The units that can provide high of 1.2 AC, or enough Amp Power 260 watt light bulb.
The inverter is converted to a DC source, such as batteries, solar panels, or fuel cell with AC power supply can be at any desired voltage, especially it can operate the AC power equipment operation design, production or correct in any DC voltage.
Grid inverter feed distribution network energy can go back, because they produce alternating current frequency of the same wave shape and the distribution system. They can also turn off automatically in the event of a power outage.
Miniature inverter converts the AC grid current directly from the individual to the current solar panel.
The 4.2 uninterruptible power supply
An uninterruptible power supply ( UPS ) using a battery and inverter, AC power supply, the main power cannot be used. When the main power to restore, a rectifier is used to supply DC power to recharge the batteries.
4.3 induction heating
An inverter converts the low frequency AC power supply with higher frequencies using induction heating. To do this, AC power supply, a first correction to provide DC power supply. The inverter of the DC power supply, then change the high frequency AC power supply.
4.4 high voltage direct current transmission
As the high voltage DC, AC power rectifier and high voltage DC power transmission to another location. At the receiving location, an inverter in a static inverter plant power conversion to AC.
Problem source request. What may not know is, in two parts capacitors may be connected in series to the second lamp, which eliminates this problem, as well as the stroboscopic effect caused by the mains frequency.