Abstract: Double throw switch’s security traded the class topic to matrix form converter (MC) to conduct the research. Analyzed each kind to trade the class plan, then proposed that used programmable logical element (GAL) four steps to trade the class plan, the simulation and experiment’s result confirmed this kind traded the class plan the feasibility and the reliability.
Key word: Matrix form converter; Double throw switch; Programmable logical component; Four steps trades the class
Introduction
in 1979, Italian scholar M.Venturini first time advanced the matrix form converter existence theory and the control policy. - Hands over the frequency changer with the traditional junction and hands over straight - - hands over the frequency changer to compare, the matrix form frequency changer has the obvious merit: The high power factor, the low overtone pollution, may four quadrant movements, not middle stored energy link, the volume be small, and the efficiency is high. Becomes in the present age electric drive along with the exchange frequency conversion velocity modulation technology to realize automated and the energy conservation major technique method, the matrix form converter (MC) research has become one of electric power electronic technology research hot spots.
1 matrix form converter and double throw switch
Figure 1 is the matrix form converter’s principle structure, it available hypothesized rectifier and hypothesized invertor constitution. Uses such structure to be possible to use fully hands over - straight - hands over in the converter the mature PWM technology. The three-phase matrix form converter uses 9 double throw switch composition 3×3 matrix form structure, thus in the three-phase input one may with three-phase output random connected, use certain stop-go control strategy willfully to be possible to cause the output space average output voltage for to need under the frequency the sine-wave modulation voltage, simultaneously may cause the input current sine and with the input voltage synchronism. Modulates in the process, between the composition double throw switch’s unidirectional component trades the class is the matrix form converter realizes the key.
At present commonly used IGBT combines the double throw switch mainly to have 3 forms, namely bridge-type double throw switch which synthesizes by single IGBT and the diode pipe manifold, common emitter series-opposing IGBT combination double throw switch and common-collector series-opposing IGBT combination double throw switch, as shown in Figure 2.
The bridge-type combination double throw switch random time has three component participation breakover, the breakover pressure drop is big, loses high. The common emitter and common-collector series-opposing IGBT combines the double throw switch to use two IGBT, prevents the reverse voltage using the component internal after flow diode, the structure is compact, facilitates simply, the switching loss is also low, therefore has obtained the widespread application.
2 three kinds trade the class plan the comparison
2.1 dead areas trade the class plan
The arrangement dead area avoids trading the class time input space to short-circuit, the shortcoming is when has cushion circuit and the inductive load the switch for the hard switch movement way, the cushion energy releases when will be followed the energy loss.
2.2 overlap trade the class plan
Overlap trades the class is by inputs the space short short circuit process to realize the electric current cut, the shortcoming is the current-limiting inductance volume is big, the cost is high, simultaneously also has the possibility to introduce the new overvoltage.
2.3 four steps trades the class plan
In order to guarantee that MC the input current and the output voltage are sine waves, implements the PWM control to 9 groups of double throw switches, various switches must carry on the cut according to certain rule. In order to guarantee the safe cut, identical outputs two cluster switches cannot willfully simultaneously the breakover, will otherwise create inputs two short-circuits; The three-phase switch cannot also separate, namely in two cluster switch cut period cannot insert the dead area, otherwise causes the perceptual load opening to induce the high voltage. Thus, both cannot two cluster switch overlap breakover, and does not allow to have the cut dead area, must have the strict logical control to be only then good, four steps trades the class plan to be able to satisfy this request well.
3 four steps trades the class process
Figure 3 is receives the identical load two groups of double throw switches to trade the class schematic drawing. u1 and u2 expressed that two input voltage spurt value, S1 and S2 expressed two groups of double throw switches, p and n expressed each cluster switch’s forward and reverse, uL and iL respectively are in the load output voltage and the electric current.
Four steps trades the class to realize to two double throw switches trades the class control, must both probably forbid possibly to cause the power source to have the short circuit switch combination, and must guarantee that provides at least a circulation way in the random time to the load, that satisfies these conditions the switch combination to altogether have 8 groups, is listed in Table 1.
Table 1 trades the class safely the switch combination plan
|
|
S1p |
S1n |
S2p |
S2n |
iL direction |
|
1 |
1 |
1 |
0 |
0 |
- |
|
2 |
0 |
0 |
1 |
1 |
- |
|
3 |
1 |
0 |
0 |
0 |
|
|
4 |
0 |
1 |
0 |
0 |
- |
|
5 |
0 |
0 |
1 |
0 |
|
|
6 |
0 |
0 |
0 |
1 |
- |
|
7 |
1 |
0 |
1 |
0 |
|
|
8 |
0 |
1 |
0 |
1 |
- |
Table 1 first kind on-off state cuts the second kind of switch is incorrect directly, like this will create the power source abruption. But when iL>0, 1 passes through the condition by the condition 3, 7, 5, cuts the condition 2 pieces is again feasible. When likewise, iL<0, from the condition 4, 8, 6 may also realize the condition 1 to 2 cuts. Figure 4 drew these two kinds four steps to trade the class order.
4 four steps trades the class the dead area compensation
Uses stagnates the link comparator and the zero crossing comparator obtains the direction of current, and forecast the electric current whether in dead time possible zero crossing, if not, then first step may before DSP will send out the PWM signal will complete, as shown in Figure 5, then four steps will trade the class the dead area altogether is td=tc1 tc2 tc3, after the dead area compensation’s dead time altogether will be td=tc2 tc3.
5 GAL four steps trades the class plan
GAL22V10 is the complex programmable logical component which Lattice Corporation produces, between its pin the biggest transmission time is 4ns, the corresponding counter frequency may reach 250MHz, has the CMOS structure which and fluctuation gate technology the electricity may clean, but 100 times repeatedly scratches writes, the information storage may reach 20 year long time.
Shown in Figure 6 for the matrix form converter’s some output three double throw switch phase transition chart. 1 expression is the switch breakover, 0 express the switch to shut off, first two, middle two and latter two express and three input connected double throw switches separately. In chart, ellipse frame expression stable state, rectangular frame expression transition condition. Obviously, must realize correctly four steps trades the class to need to know that the current condition, the next time condition, the load current direction and the timer trade the class time, the judgment obtain correct trade the class signal and the order and output each IGBT component’s electronics grid, completes trades the sequential logic which the class needs.
6 experiment simulations
Figure 7 is in the experiment a pair of double throw switch trades the class process the actual profile, Figure 8 is in the experiment two is trading the class process to the switch the actual profile, obviously? Crosses DSP to realize between switch’s security to trade the class successfully. May also (MC) the double throw switch four steps trade the class process through simulation software Matlab/Simulink to the matrix form converter to carry on the confirmation, uses the perfect switch to trade the class process to a matrix form converter electric circuit to carry on the simulation, its output voltage simulation profile as shown in Figure 9.
In the experiment uses IGBT by the collecting electrode counter-series combination constitution double throw switch, Figure 10 outputs the line voltage experiment profile.
Observes on the IGBT component between the collection, the emitter the voltage waveform, the voltage overswing which obviously four steps trades the class to be possible to trade the component when class produces to limit in the reasonable designation voltage tolerance scope, guarantees the component trouble-free service.
7 conclusions
This article (MC) the double throw switch four steps trades the class plan in view of the GAL control’s matrix form converter to carry on, then as the core constituted the matrix form converter’s hardware system take DSP, has designed the control system software, has completed the asynchronous machine dragging experiment. The experimental result has confirmed this plan validity.
