Protection against short circuit in a payment of management of the inverter.
- inverted rectifier is ungeared, does not work.
- Direct current of closure of the bridge. There are two types.
Malfunctions in a food инвертерного the air conditioner. Protection against short circuit in a payment of guidance of the inverted rectifier.
The inverted rectifier directly is related to a loading frequently difficult and users, as the user of a loading of an error of the inverted rectifier of conducting as a result of malfunction.
This article is necessary for repair of the inverted rectifier, short circuit of the air conditioner with the smooth starting, debugging methods through the bridge from an overload on a current, protection methods to raise reliability of the UPS of the air conditioner.
The UPS, — as necessity of achievement of a long-term uninterrupted food with critical loadings which are made for pinch of reliability of air conditioners, flattening of critical values of a current.
In practical appendices for the user, or the hand-operated bridge of short circuit or the inverted rectifier can be related to the help with operative the errors caused by ecological factors, such as an exit of the UPS, this time, the inverted rectifier will have a major current through the transistor (IGBT explanations for this article, also it can be applied by analogy with MOSFET),
If not such current of short circuit of detection and protection against effective activities, IGBT the collector or a sink current is much more exceed fields of safe operation, behind instantaneous a high current leads to a high power loss.
The malfunction can be because of an excessive voltage from an overload on a failure current.
The uniphase semi-bridge inverted rectifier, for example (fig. 1 see), the analysis of an exit of the UPS of the inverted rectifier in a full-wave circuit and through current protection.
Target protection against short circuit: necessity of the UPS constantly to maintain action of a current of short circuit and inverted rectifier maintenance, — can be closed after 200 мс that demands short circuit of the current proceeding through guidance IGBT ICRM (an iterated peak current, blanket ICRM = 2ICnom).
bridge of through protection of the inverted rectifier:
Short circuit or inefficiency VT2, natural exterior electrical connections.
To put it briefly, when are unclosed in VT1, ВТ1, it is immediate through a short circuit current increases through it very promptly, usually during 10 мкс,
That occurrence of the bridge a hand directly can rise on rated current IGBT some times, you need to find out promptly malfunctions, and IGBT interlocks the driver and deadlocks, command dump while system have not allowed to unclose a signal disk again.
In the full service life, as a rule, IGBT to counter such direct current, cannot exceed 100. Such direct requirements for protection in 10 мкс, the current in IGBT does not exceed ISC (transitive a peak current, blanket ISC = 4ICnom) before to banish, and also to close the inverted rectifier.
Exit, — protection against short circuit
At expressed four present data units erected for detection Lf a Ruhmkorff coil the HALL of a current of short circuit on an exit arises, when, in case of opening VT1, VT1 and voltages through Ruhmkorff coil Lf plan UC1.
Ruhmkorff coil present prompt pinch to detection of this current for a certain gamut (above normal workers flowing, iterated the peak current makes less ICRM), VT1 VT2 and controllabled blockade.
This time the inverted rectifier Ruhmkorff coil has started to impinge, when the current of a food of the air conditioner impinges to a certain degree, — is excellent drivers of interlock of a signal.
If the exit of short circuit and this process occur, the current induction starts to grow.
- Protection against short circuit in a point,
Once again blocking IGBT of drivers etc. 200 мс, the software can spot a logic exit, — as short circuit has occurred at this time.
inverted rectifier is ungeared, does not work.
2 bridges through protection against an overload current
- First, to avoid downwards a tube on tube VT1 VT2 and it is high because of a signal disk simultaneously, arisen on failures, on the one hand, should view addition the driver it is dead, it also needs in a tube on hardware plans a disk of a signal of hardware interlock, when upper and inferior guidances of a drive unit level, whereas the real level, Self-acting interlock of a driving voltage.
Besides, IGBT overvoltages the avalanche can lead also to instantaneous through breakages or a failure their natural plans, because of the exterior parents the electrical connection has caused short circuit then will be scored 2,3,4 at a high current through measures of protection flowing a variety the converter the bridge through occurrence possibility, cannot avoid completely a hand how to reach the bridge on a place at the expense of timely detection of malfunctions and protection by means of IGBT, IGBT, to avoid burning, it is especially important.
Direct current of closure of the bridge. There are two types:
(1) detection a busbar current (Drawing 2 see)
When the bridge busbar Ip current is suddenly incremented to spotted in the multiple rated current, bridges which occur through a dip, and then to block all an IGBT-drive for elimination of failures and to avoid IGBT have burnt.
Such loops for a uniphase current changer in small capacity, or high capacity for three-phase converters or the transformer.
Busbar current the high, uniphase bridge under a hand, in IGBT damages before its change IP it is not clear, cannot be realised are effectively protected.
(2) at an overload on a current of detection an optron (for example HCPL316J).
Shows performances IGBT, IGBT inserts, With, Е with a current voltage.
Linear relation, IGBT can sustain 10 мкс four times rated current, — a peak current through a saturation, finding out UCE.
Pressure drop for definition IGBT of an overload on a current, thereby blocking a signal disk. The blanket plan is shown in drawing 3.
HCPL316J The disk is active at high level, where point DESAT 0.25mA, — a typical charging current for gymnastics of the condenser With.
When IGBT at insert occurs when overloads on a current.
UCE UCE, — sharp magnification of protection on set of a voltage, DESAT contact when the charging voltage more than 7В, HCPL316J is automatically blocked a drive unit, soft lockouts IGBT which is not protected by major current IGBT.
- Under the formula I × △ Т = With х △ U, it is possible to calculate DESAT contact the charging voltage to 7В time necessary for 2.8μs, in a combination with operational time HCPL 2 мкс, can guarantee its protection does not exceed blanket operating time IGBT can maintain overloads on a current 10 мкс term, also is able provide, that before record in IGBT-lockouts.
Century Д is function the diode of a current of conductivity, for detection IGBT protection UCE of pressure drop (DESAT) joins, to ungear, blocking basic chains. In IGBT at lockout, IGBT on higher between СЕ дуче / д, and thus to lead CE between the condenser the gymnastics current.
- What to avoid false operations because of the charging current, the diode is better to use, — prompt diodes. Protection against short circuit threshold voltage UCE, malfunction (), the comparator can be erected within HCPL316J reference voltage Uref (Uref = 7В), and number of diodes in a series with a gang.
Actually amplifications of protection of power failure between СЕ, — as dot protection of a voltage
UCE, malfunction () = Uref-n × UF
Where this number of diodes in series UF is the diode of power failure abroach.
Through the bridge a hand, actually there is a signal protection as is shown in drawing 4.
3. The inference
- To refine reliability of the UPS of the air conditioner, for maintenance of its malfunction in certain cases the self-defences, a necessary food of the inverted rectifier and the module is considered is overloaded on a current of a measure of protection.
First, it should in the shortest to fault of super-currents time it is found out to distinguish an exit short circuit or failure through the bridge a hand, and then to accept a corresponding expedient of protection of the module of a food of the air conditioner.