The EPS emergency power supply has been widely applied to the construction electricity domain and the special emergency power supply situation. Develops along with the society, more is the information, the modernization, relies on the electric power. The sudden power failure inevitably can give the people the normal life order and the study brings the influence, in particular regarding in production, life specially important load, once the severance power supply, will be able to create the significant economic loss. However, the electric power breakdown has the burst characteristics, take people's will as the shift, even if the electrical network facility is again advanced, the accidental power failure also is unavoidable. At present, the city power supply system security countermeasure generally uses the incorporation power supply, provides the reliable power source protection for the city electric power. But from the enterprise and the industry, the civil construction service condition looked that, merely depends on the public electrical network by far to be also insufficient, must have the emergency power supply system (EPS), the emergency electric power which its importance is in which the accident has the situation guarantees provides needs, to effectively reduces the loss which creates because of the power failure, produces for the people with the life safely provides the safeguard. Therefore, EPS is also called "the city lifeline system" important constituent.
1.1 EPS emergency power supply classification

At present in the market EPS emergency power supply brand is multitudinous, everybody the control mode and the control method which uses in the design 不尽相同, but aims at brings load the type approximately to be allowed to induce into following three kinds: One is mainly uses in the emergency lighting and emergency lighting single-phase EPS is corresponding the our company the WY series; Two, uses in beside the emergency lighting, the emergency lighting, but also has applies mix power supply three-phase series EPS which to air conditioning, the elevator, the volume curtain gate, the exhaust air blower, the water pump and so on the inductive load or has both at the same time is corresponding the our company WYS series; Three is directly corresponding to electric motor power supply frequency conversion series EPS the our company WYS/B series.
1.2 EPS emergency power supply design request

The EPS emergency power supply may say is a nearly two year only then swift and violent development emerging industry, compares says to development mature UPS, has same place, also has differently place. Its same spot lies in all has (severance) in the situation continues in the city electricity breakdown to the load to provide the alternating current supply the function, has used the IGBT inversion technology and the pulse-duration modulation (PWM) the technology. Similarity is UPS besides provides the uninterrupted power supply, but also has both the improvement city electricity quality the function, but EPS emergency power supply then mainly solves time the city electricity breakdown emergency power supply problem; UPS mainly is the IT profession equipment provides uses electricity the safeguard, the EPS emergency power supply is suitable for each profession; UPS power supply pattern request cut time very short (0 ~ 10ms), the EPS emergency power supply then relative is wider (0 ~ 4s); UPS main belt computer class load, but the EPS emergency power supply brings the load to be promiscuous; UPS is higher regarding the movement environment request, the EPS emergency power supply requests to be able to adapt each kind of environment; UPS by the common user monitoring primarily, the EPS emergency power supply mainly uses in emergency to supply power, request and fire linkage; UPS unimpededly maintains the intelligence transmission primarily to want the goal, the EPS emergency power supply to guard against the significant disaster accident primarily to want the goal. May vividly the analogy, UPS to "rescue the data" primarily, but EPS to "rescues the person" primarily. The general EPS power is bigger, machine in inversion is at the readiness condition.

In view of the fact that the EPS emergency power supply main design thought is when the city electricity sudden stop provides the safe reliable emergency electric power supply, effectively avoids having time the disaster person casualties and the property damage is the principle. Therefore, when designs EPS should emphatically consider its security, the reliability, the serviceability and the rationality. Mainly has:
1) the power failure switching time generally in a millisecond level (25ms), guarantees the power supply timeliness;
2) load adaptiveness strong, including 电容�? 电感�? mixed type load, moreover the overload capacity and the anti- impact ability are strong;
3) has the multichannel output, prevented the output solely forms breakdown;
4) has the fire linkage and the long-distance control signal, but manual and automatic interconversion;
5) environment adaptiveness strong, is suitable to each kind of adverse circumstance, has prevented the high low temperature, is hot and damp, the salt mist, the dust, the vibration and the mouse nips and so on the measure;
6) the service life is long, has the battery rapid charge rate ability and the management ability;
7) conserves energy, operating efficiency high, the movement cost is low;
8) whether there is does the person value defend, the automatic operation function;
9) reports to the police the function to be complete, can promptly provide each kind of unusual condition reporting to the police;
10) has the strong start function, after avoids the battery link protection being unable to start;
11) does not have the smog, does not have the noise, does not have the environmental damage and so on;
12) maintains simply, the maintenance cost is low.
1.3 EPS emergency power supply principle of design

1) the emergency lighting and emergency lighting class illumination EPS generally take single-phase primarily, mainly as the emergency lighting situation (market, recreation area, work place, transaction place and so on) provides the centralism power supply, like chart 2 shows. When inputs the power source normally, a city electricity group through switching device output for daily illumination, another group through battery charger to group charging, when the controller examines the city electricity severance either exceptionally (somewhat low or is high), to the inversion sends out the start signal, and the control mutually throws the switching device to transfer to the inversion output. Certainly, is different regarding the EPS connection, but also may treat as EPS two groups power sources, three groups power sources uses.


Chart 2 illuminates the EPS power supply system
2) the emergency lighting and mixed type load 类此 type EPS generally is suitable for the load nature quite complex situation, for example both has the illumination load, and has the power load, therefore generally to three-phase is in the majority, like chart 3 shows. Suitable situation for guesthouse, high-rise construction, hospital, large-scale market and so on.

Chart 3 mix load EPS power supply system
3) the electrical machinery special-purpose frequency conversion starts 类此 kind of type EPS mainly to design for the electrical machinery class load, avoids because the electrical machinery starting in the process the big electric current impact to damage the equipment. Is widely applied to the high efficiency electric motor load, for instance elevator, fire pump, large-scale air blower and so on. Similarity is this kind of EPS generally only has the single-channel with other EPS to output, like chart 4 shows. After three-phase loses the enter the market electricity is normal after the rectification to the inversion provides the direct current, simultaneously passes through the battery charger to the group charging; When three-phase input power failure or exceptionally, from turns provides the direct current by the battery to the frequency changer. When needs the electrical machinery load work, gives the frequency changer start signal (movement signal, long-distance control signal and so on), the frequency changer can output immediately. From 0 ~ 50Hz frequency conversion, the supplies electric motor carries on the frequency conversion to start, after its frequency arrives 50Hz to maintain the normal operation.

Chart 4 electrical machinery special-purpose EPS power supply system
1.4 EPS emergency power supply domain present situation

Along with the technical unceasing development, the multitudinous intelligent building rises straight from the ground, the people while proposed higher request to its environment, also proposed the electric power safeguard and the fire prevention security problem. But the EPS start compares the generator and UPS must be late, the people are also insufficient to its understanding degree, therefore in multitudinous emergency power supply situation, or as the main emergency power supply way realizes the EPS function take the generator and UPS. Speaking of provides the emergency power supply ability, these two ways have exposed many deficiency.
1) with the diesel oil power set took the emergency power supply is, also is the most common emergency emergency power supply which the present majority of projects uses, because diesel electric engine capacity bigger, but and machine the movement also the continuously on time are long, therefore already had the longer application history. However, regardless of the generator starting rate is much quick, causes the generator after the power cut to receive the activating signal to start, to the generator voltage, the frequency and so on achieved stable may supply power when up to, at least needs factor ten s to count min, this period of time, all current collector knock off, possibly creates the minority equipment the damage or appears the life and property the security problem. But the EPS start generally cannot surpass 25ms, therefore cannot affect the equipment the normal work.
On the other hand, diesel electric engine application in emergency power supply situation, some many disadvantageous place, including:
(1) in the high-rise construction, the diesel oil power set generally puts on the basement, the design difficulty in a big way, the construction cost is high, provides the wind, cooling, discharges fume, the absorption of shock, 消音 and so on the facility all needs fully to consider;
(2) has the fire hidden danger. Its oil pot likes extremely dangerously "the bomb", 11,000 catches fire, the consequence is inconceivable;
(3) routine maintenance quite frequent, the work load is big;
(4) the diesel electric engine noise is big, has the environmental damage;
(5) discharges fume has the massive sulphur dioxide, the pollution is serious, affects the environmental protection.

Take the load capacity as 200kW is the example, compares with EPS and the diesel oil power set's natural price to compare. When selects EPS, its rated power and the load power ratio are 1: 1 then, its total price approximately is about 600,000 Yuan. But selects the diesel oil electricity generation machine-hour, its rated power and the load power ratio should be 1.3 ~ 1.5: 1, to the 200kW load, the diesel oil power set needs the 250kVA specification, this unit price is about 400,000 Yuan, but except unit itself price outside, but also needs the sur- other auxiliary unit expense approximately 16 ~ 290,000 Yuan, presently take 200,000 Yuan computations, namely selects the diesel oil power set total price as about 600,000 Yuan. Therefore, the two price difference are not many. Is not difficult to see, if the EPS capacity is smaller than time 200kW, its price must be smaller than the diesel oil power set's comprehensive construction cost. At present the fire emergency power supply situation load aggregate capacity generally below 200kW, considered from the investment long-term benefits that, EPS compares the diesel oil power set economy many.
2) with UPS took emergency power supply EPS is mostly the same except for minor differences from the principle structure and UPS. On-line UPS no matter city electricity is whether normal, it all continuously by the inversion power supply, namely defers to "the city electricity input -> rectification -> inversion -> output" the order carries on, only has when the inversion breakdown or the overload only then changes by the bypass outputs, like chart 5 shows. But EPS, when the city electricity is normal, the city electricity gives the load through the switch S output, simultaneously battery charger to battery charge. When the control system examines the city electricity power cut, the inversion work, causes the switch S cut to the contravariant output condition, provides the electrical energy to the load, like chart 6 shows.

Chart 5 UPS power supply system


Chart 6 EPS power supply system
Supplies power the diagram from above to be allowed to see, UPS is one kind of double transformation structure UPS, mainly provides the stable high grade electrical energy for the load, not city electricity electrical network influence, moreover its switching time generally in 10ms, therefore, UPS is widely applied to the computer, the program controlled switch, the medical equipment and the precise electronic instrumentation and so on cannot sever the power supply the place. But just because UPS not only is shouldering outside the emergency power supply, but also is undertaking the improvement electric power quality task, therefore its inversion must continuously unceasingly work, service life relative shorter, generally is 5 ~ 8 years, the battery replacement is in particular frequent. On the other hand, the UPS inversion is in for a long time the work, own loss bigger, moreover for uses the environment request to be very high, only can put in calculates in the engine room or the air conditioned room.
UPS specially is the IT profession computer class and the communication class load designs, its load adaptiveness is inferior to EPS, explains with examples, if emergency supplies power the situation to include an exchange induction type electric motor kind of perceptual load, then can have the very big problem in the UPS design shaping and the use. Because the motor initial firing current usually is its nominal current 5 ~ 7 time, but UPS overload capacity standing operating procedure that, When overloads 125%, A kind is 10min, B kind is 1min, C kind is 30s; Overloads 150% time 10s. If wants UPS to be able to withstand the electric motor initial firing current the impact ability, the potential essential increases UPS the rated capacity, this will enlarge the investment without doubt, but also not necessarily will be able thorough settlement the problem. Therefore, selects UPS to take the emergency power supply, the work is already unreliable, but also must spend the massive funds.
2 UPS/EPS development tendency
2.1 UPS/EPS control technology

Middle and small scale UPS/EPS AC/DC and DC/the AC transformation majority still used the simulation control circuit, AC/the DC converter control chip majority integrated, use simple, the work is reliable. DC/the AC converter control has two essential ways, one kind is the single closed-loop control, another kind is the double closed-loop control. Former control circuit is simple, but difficulty with realizes the out-port to short-circuit the self-recovery. Latter control has the electric current inner rim and the voltage outer ring, the voltage regulator output for current regulator assigning, therefore, the limit electric current assigned the peak-to-peak value also to limit the inversion maximum output electric current.
Presently, the numerical control has become the new UPS/EPS control technological development the mainstream, the digital controller has the precision high, antijamming ability strong, is easy to realize to the UPS examination, the breakdown diagnosis and the isolation, is easy to realize the remote control telemetering, realizes many UPS parallel and hotly inserts pulls out, is easy to realize to the accumulator cell monitoring and the management. In other words, the computer involvement caused UPS to have the intellectualization, was allowed to cause its movement at the most superior condition.
2.1.1 DSP application

Uses the digital signal processor (DSP) the digital PWM technology, is the numerical control technology core, uses in to guarantee the UPS/EPS output voltage the quality, namely the guarantee output voltage, the frequency and the output voltage profile satisfies the technical specification the request. The numerical control another important function is realizes the UPS/EPS initial self-checking and movement self-checking, carries on the fail safe and the failure isolation, this is simulates the controller to be unable to be competent. As a result of the digital controller flexibility, enables the UPS controller the hardware electric circuit to be allowed to standardize, thus simplified the production, the use and the service, also greatly enhanced the operational reliability.
2.1.2 control circuits entire microprocessor

The UPS/EPS electric circuit is composed by the below several parts: The main circuit, actuates the electric circuit, the monitoring to demonstrate and to control the protection circuit and the correspondence contact surface electric circuit. Monitoring, the demonstration and the control protection circuit and the correspondence contact surface electric circuit, may simplify its electric circuit using the digitized design skill, and solves the original analogy electric circuit to need to adjust, to have warm floats and parameter adjustment not easy lacking. Uses the method is:
1) the entire microprocessor carries out the monitoring, the demonstration and the control protection circuit and the correspondence contact surface electric circuit function using the microprocessor;
2) half microprocessor use analogy electric circuit processing fast feedback protection circuit, but by the processor processing idling speed feedback, reports to the police, the demonstration and the correspondence contact surface function.
2.2 accumulator cells technologies
The accumulator cell is the UPS/EPS heart, no matter the UPS/EPS electric circuit is advanced, its performance finally is decided by its battery, once the battery expires, good UPS/EPS also is unable to provide the uninterrupted power supply.

At present, UPS/EPS generally all uses exempts the maintenance seal lead-acid battery, because uses the negative pole absorption type seal technology, overcame the ordinary accumulator cell to need regularly to make up the water the shortcoming, had "exempts the maintenance", the easy to operate, does not pollute the environment, the volume is small, the weight light merit. It uses Gao Qingguo the electric potential the slab lattice material, reduced the battery in depositing and the charging-up gas decomposition. The positive electrode surface superfine glass fiber membrane, prevented the active material to fall off, enhanced the battery life. The safety valve use causes the accumulator cell very little to produce the gas, also may cause the oxygen which produces to absorb by the cathode lead, causes the accumulator cell anhydrous loss, had achieved the seal exempts the maintenance the goal.
In the ordinary circumstances, affects the battery performance the primary factor is the trickle charge, the battery trickle charge approximately must reduce a half service life. At present overseas uses one kind of ABM (Advanced Battery
Management) three stages batteries management plan, namely the charge divides into three stages: The first stage is 恒流 the equalizing charge, imitates the battery capacity to 90%; The second stage is the floating charge, imitates the battery capacity to 100%, then stops charging; The third stage is the nature electric discharge, in this stage, the battery uses own leakage to flow the electric discharge, continuously arrives the stipulation the voltage lower limit, again duplicates the above three stages. After this way changed before that kind to fill the electricity, still caused the battery to be at day 24h 浮充 the condition, therefore lengthened the battery life.
The metallized nickel hydrogen battery has the high energy density the merit, moreover does not have the cadmium pollution which the nickel cadmium cell possibly creates, applies it to UPS/EPS may receive the small 轻量 merit. But its shortcoming is the selling price too is high. American Alupower Corporation researches and develops the power lead - air emergency power unit (RPU), movement >= 50h, the power from 600W to 6000W, the voltage has DC24V and the 48V two kinds, its energy density is plumbous acid battery more than ten times, the weight only has the plumbous acid battery 1/10, occupies the space only to have the plumbous acid battery 1/7, hopefully substitutes for the lead-acid battery to apply to UPS/EPS.
3.3 EPS emergency power supply development tendency
Because EPS brings the load type the complexity and the environment relative constancy, in view of the different situation, the different load, may do to the EPS function draws close to the reality application. Including following several aspects.

1) structure composition ordinary EPS in order to unifies the practical application well, often uses "gathers one" the structural design, but as a result of load and environment complexity, also from this brings the equipment standardization and the design institute, the user shaping difficulty. Solution uses the modular design, separates the main engine and the input or the output power distribution. The main engine module completes the main energy conversion and the communication control function; Power distribution module realization rich power distribution management function. The main engine module through the standard control connection realization to the power distribution module management, like the double power source automatic cut over function, the multi- return routes output function, the fire linkage function should realize in the power distribution module.
2) the power distribution module should increase function EPS to use in the urgent load power supply, its load often for non- sole load, but these loads 不尽相同 in the emergency case essential degree, therefore, said regarding EPS, certain power distribution management functions are very important.
(1) the smooth start function such as, the EPS load very major part is the perception shock load, has the bigger starting current, when shaping must enlarge the EPS capacity, thus creates the equipment resources the waste as well as the user cost increase. In fact, as a result of the EPS load power supply may the discontinuity, EPS be possible to increase 8 groups or 16 group programmable power distribution management connection, through the order, the time which starts to the load carry on the control, may solve the start surge current in the very great degree and enlarge the shaping capacity the question.
(2) the partial unloading function decided by the EPS load nature, when overloads occurs, needs EPS as far as possible to continue to work, but cannot look like UPS such to carry on protection closing machine, therefore, similarly passable power distribution management connection dismantle secondary load.
3) battery management because the EPS use environment generally compares UPS to be bad below, for lengthens the accumulator cell as far as possible the service life, the battery charger should simultaneously have the function:
(1) may establish the charge to limit the class;
(2) may establish the battery discharge final voltage;
(3) has the automatic 浮充 function, the charge mechanism should conform to the DIN41773 standard;
(4) has 浮充 the voltage temperature compensation function;
(5) intelligent battery examination function;
(6) the deep electric discharge protection (may force emergency).

4) the frequency conversion starting function at present the frequency conversion starting EPS design, like chart 8 shows, mainly focuses to a solution bigger electric motor, like load and so on elevator, water pump, air blower starting impact question, but a more reasonable design, should be on-line UPS and the frequency changer technology perfect union. On-line UPS has the mature rectification, the battery management technology; The frequency changer has the mature frequency conversion control technology, two organic synthesis are this application domain ultimate development directions.

Chart 8 frequency conversion starting
Conclusion
Along with society's progress and the development, the environment request unceasing enhancement, fire consciousness more and more is also taken by the people. EPS is known by its unique superiority by the people with the use, in a project, it may the nimble utilization in the fire power supply return route terminal, the individual important situation and so on the many kinds of situations. On the choice emergency power supply, no longer only limited to the diesel electric engine, because they respective characteristic separately was suitable for the different project, this will provide a more powerful safeguard for the entire society's security.

Reference
1 "Civil construction Electricity Design Standard" Chinese plan publishing house,1,993
2 GB17945-2000 country standard (fire emergency lamps and lanterns)
 3 "Emergency power supply Uses EPS And UPS" Li Chengzhang
4 Zhejiang 韦德 electron limited company enterprise standard
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