[introduction] nobody drive aircraft (UAV) or ” unmanned aircraft ” using increasingly at heavy-duty applying, if military affairs, fire control is mixed,agricultural ground scouts. Above these application and a lot of other using exemple ask not to have man-machine to fly for a long time in sky, so batteries is not an option. Contrary, unmanned aircraft passes cable of a moorage to provide power source in flight process.

Nobody drive aircraft (UAV) or ” unmanned aircraft ” using increasingly at heavy-duty applying, if military affairs, fire control is mixed,agricultural ground scouts. Above these application and a lot of other using exemple ask not to have man-machine to fly for a long time in sky, so batteries is not an option. Contrary, unmanned aircraft passes cable of a moorage to provide power source in flight process.

However, tether brought new challenge. Thicker tether although resistor is inferior, but weight is great, bring bigger negative charge to unmanned aircraft, limitted its carrying capacity. Fine cable although weight is light, but increased resistance, and because do not have man-machine tether normally longer, because this meeting creates not acceptability power dissipation and tension,drop. Engineers are being sought will decrease through heightening tether tension 800 bend over fine the loss that cable brings. The addition of such voltage conduces to the electric current that reduces certain power to ask to fall.

Next, the challenge turned processing into the tall voltage in unmanned aircraft. The low voltage that can accept tall voltage and must fall its effectively to need to place of unmanned aircraft system without the distribution network of man-machine. Solutions of any power source government must be deft, with reducing the effect of pair of aircraft carrying capacity as far as possible.

The article discussed moorage not to have the advantage of the high-pressured power supply system of man-machine. Explained next when using design distribution network without man-machine for moorage, why efficient the module of bus line converter with high power density (BCM) and 0 voltage switch (ZVS) step-down converter is a very good choice. Introduced to come from the BCM of Vicor and example of ZVS step-down converter finally, use at the help to reveal how to design a deft and efficient power source network.

Voltage is taller, cable is lighter

Tether let an architect cast off the batteries limitation to unmanned aircraft (graph 1) . Hypothesis ground has power source to be able to be used, unmanned aircraft can maintain for long in sky, the play in can letting them observing platform or exceed the application such as repeater of apparent distance radio is used. Defect is, unmanned aircraft must be in very may heavy cable condole headroom, this may restrict its work limits and effective load (like camera or radio equipment) carrying capacity.

Graph 1: Unmanned aircraft can use the electric power that provides through tether to stay for long in headroom. (picture origin: Vicor)

Business needs a variety of volts d.c. with all sorts of systems of unmanned aircraft. For example, 48 bend over are the common voltage of electric machinery, and 12 bend over, 5 bend over and 3.3 bend over are sensor, carry out implement the typical voltage with control electron equipment. Fine and light tether conduces to the weight negative charge that limits unmanned opportunity, but the resistor of cable is taller (resistor reduce and increase of cross section as cable) , when using power source of 48 bend over, can cause not acceptability high pressure to fall (define the voltage drop that is cable far end to be more than source voltage 3% to 5% ) the power dissipation with long cable.

Of cable fall and pressing is not voltage. Accordingly, for example a commerce needs 1.5 kilowatt without man-machine (of KW) constant power, carry power supply of power source of 48 bend over, will need 1500/48=31.25 ampere (the electric current of A) . We can provide same power through heightening tension, reduce voltaic demand thereby, reduced voltage drop and power dissipation subsequently. For example, the electric current of the need when using power source of 800 bend over is 1500/800 = 1.9 A only. Voltage of this kind of power supply allows an architect to use light-duty cable surely.

One kind is used at the distribution network of unmanned aircraft

To use taller power supply voltage and lighter tether, the engineer needs to design distribution network, the working voltage that the tall voltage that makes be carried in tether can fall effectively to need to place of unmanned aircraft system.

Graph the 2 example that showed a such networks. Compose builds the BCM that this network is use Vicor and ZVS step-down converter.

Graph 2: Moorage does not have the distribution network of man-machine. If where,the bus line of 48 bend over that notices to be used at ground system please is 800 hot season promote in tether, how reduce 48 bend over again on unmanned aircraft next. (picture origin: Vicor)

In this example, the alternating current changeover of 208 bend over is BCM general three-phase the dc of 48 bend over, offer all of ground computer science department of unmanned aircraft to use. Next ZVS step-down converter reduces the power supply of 48 bend over to be used to each ground facilities 12, 5 with 3.3 bend over. Subsequently the direct current source of 48 bend over arrives by step up of the 2nd BCM 800 bend over, drop with reducing tension as far as possible and the power loss in tether.

On unmanned aircraft, reduce tension 48 bend over by the 3rd BCM. Without man-machine medium distribution network includes farther step-down converter, offer proper voltage for camera, sensor and logistic parts of an apparatus.

The commendation of this application the BCM4414VD1E5135C02 that BCM is Vicor and BCM4414VH0E5035M02, former use at initiative the changeover of alternating current of 208 bend over to dc of 48 bend over, latter is used at the changeover of dc of 48 bend over to dc of 800 bend over.

BCM4414VD1E5135C02 works on the 260 bus line to 400 bend over, offer the 32.5 low-pressure side output to 51.3 bend over. This parts of an apparatus can provide the electricity of successive and low-pressure side of highest 35 A, every are cubic centimeter (W/cm3) power density is as high as 49 tile, peak value efficiency is 97.7% (graph 3) .

Graph 3: Does the module of bus line converter of Vicor show good efficiency inside range of wide low-pressure side electric current (TCASE = 25? C) . (picture origin: Vicor)

BCM4414VH0E5035M02 moves on the 500 bus line to 800 bend over, offer the 31.3 low-pressure side output to 50 bend over, output of the greatest permanent power is 1.5 kilowatt. Density of electric current of successive and low-pressure side, power and peak value efficiency and its sister product are same. BCM uses millimeter of 110.5 X 35.5 X 9.4 (the crust of Mm) , weigh 145 grams (G) .

Vicor BCM still offerred agile heat management to choose, its coping and bottom thermal resistance are very low. Through using these parts of an apparatus, architect of power source system can reduce tether and establishment of area power supply and unmanned chance dimension and weight.

The BCM of Vicor is DC-DC power source, because this is in,pursue before the first 2 medium BCM, must original three-phase 208 volt communication input changeover to be dc. Applying to the parts of an apparatus that communicates rectification is module of Vicor communication input (AIM) , be like AIM1714VB6MC7D5C00 (graph 4) . AIM equipment can accept the communication input of 85-264 bend over, offer the communication output of a commutate, electric current is highest 5.3 A, power is supreme 450 tile.

Graph 4: BCM needs the communication input of a commutate. Like the three-phase AIM module of Vicor such equipment offerred a solution. (picture origin: Vicor)

The step-down that has high power density and flexibility adjusts

Once earth station or the BCM in having man-machine adjust voltage,48 bend over flow continuously, with respect to need ZVS step-down converter reduces tension further, so that to each systematic power supply. It is especially in unmanned aircraft, step-down converter must have high power density and efficient, such ability forms the power source of a compact, small amount. ZVS step-down manostat suits this task very much.

The switch loss inside traditional manostat MOSFET is efficiency low next main factor, have negative effect to power density. ZVS overcame these loss, the step-down to inputting an operation with opposite taller voltage is a special advantage for converter.

ZVS (also say ” soft switch ” ) the mechanism is very complex, but can regard it as MOSFET guides the wide modulation of traditional arteries and veins during connecting (PWM) power changeover, but have ” syntonic ” switch is handed in more. The adjustment that outputs voltage is to pass the changeover frequency that changes switch manostat to adjust occupy sky comparing effectively (adjusted so ” open ” time) of implementation.

During ZVS switch closes, the L-C circuit of manostat produces resonance, the voltage that makes this are shut from 0 span to peak value, answer when this switch is activationed again next 0. In this process, no matter working frequency is mixed,input voltage how, the MOSFET of switch manostat is handed in exceed loss for 0, this meant big political integrity to save power, improved efficiency considerably. Refer to ” 0 voltage switch reachs his voltage adjustment importance is summed up ” . )

Vicor produces a series of ZVS step-down manostat, with control semiconductor of circuit, power is mixed support package one case compositive enclose in high density LGA, BGA and systematic level (in SiP) parts of an apparatus. Switch manostat is the complement of use BCM of place of other to circuit of unmanned aircraft distribution part. ZVS step-down manostat is nodded for efficient load (PoL) DC-DC adjustment provided good power density and flexibility. They can be used bus line of 48 bend over effectively step-down reachs 3.3, 5 with 12 bend over, in order to be used at subsystem of other and unmanned aircraft.

The example of ZVS step-down manostat includes PI352x-00 series. It is OK that PI352x-00 manostat needs two an exterior inductor, voltages to choose resistor and least capacitor only make a complete DC-DC switch mode step-down manostat. All manostat are in 30 to 60 bend over input condition leaves the job. This series has 3 parts of an apparatus: 1. PI3523-00, offer nominal 3.3 bend over are outputted (2.2 to limits of 4 bend over) the electric current with highest 22 A; 2. PI3525-00, offer nominal 5 bend over are outputted (4 to limits of 6.5 bend over) the electric current with highest 20 A; 3. PI3526-00, offer nominal 12 bend over are outputted (6.5 to limits of 14 bend over) the electric current with highest 18 A. These parts of an apparatus all are offerred with the LGA SiP of 10 X 14 X 2.56 Mm.

Add ZVS manostat to power density network

We need to undertake work of a few designs will optimize the function of the ZVS step-down manostat in network of unmanned aircraft distribution. Graph the exterior element that every 5 members that showed PI352x-00 set require.

Graph 5: The network of resistor voltage divider that manostat of Vicor ZVS step-down needs an an exterior inductor, setting to output voltage and the capacitor that are used at filter wave. (picture origin: Vicor)

These parts of an apparatus need an exterior inductor. Vicor was calculated store can the inductance value of device, change in order to make efficiency the biggest. To PI3523 and PI3525 manostat, the proposal uses 230 accept go smoothly (NH) inductor, and to P13526, the proposal uses 480 NH inductor.

Although every member of PI352x-00 series can handle the dc of 48 bend over that comes from respective BCM to input directly (the input limits of step-down manostat is 30 to dc of 60 bend over) , but setting output voltage needs to choose to output resistor (REA1 and REA2) , these two resistor formed network of voltage divider of a resistor jointly.

No matter output voltage how, REA2 should be installed it is 1 1000 Europe (K Ω ) , fight ability of a confusion of voices in order to obtain first-rate. The value of REA1 can calculate through the following formula:

   Formulary 1

Besides inductance value, vicor still recommended the value of CIN and COUT capacitor, in order to ensure of power level be started correctly and high frequency go Ou. Guide when MOSFET of side of town report high pressure when connecting, PI352x-00 series almost from its all and high frequency electric current is absorbed in capacitor of low impedance pottery and porcelain. Next, during MOSFET is shut, capacitor can charge from power source. Watch 1 listed capacitance value and the ripple electricity that produce from this and voltage.

Product    Load current (A)    CIN    COUT      CIN ripple electric current (IRMS)    COUT ripple electric current (IRMS) VIN ripple (MVPP)    VOUT ripple (MVPP)    Load pace (of rating % ) (S of 1 A/ μ )    The instantaneous deviation that does not include ripple (MVpk)    VOUT restores time (μ S)
PI3523    22    F of μ of 10 X 2.2    F of μ of 8 X 100    7.3    16.1    900    75      50 to 100    110    <80
PI3525    20    F of μ of 10 X 2.2    F of μ of 12 X 47    8    14     960    75    50 to 100    160    <80
PI3526    18    F of μ of 10 X 2.2    F of μ of 8 X 10    10.1   11     700    210   50 to 100    260    <80
Express 1: Vicor P1352x input and output capacitor are in nominal line voltage and nominal below small tone pitch recommend a value. (form origin: Vicor)

To ensure the optimal efficiency of PI352x-00 series and low electromagnetism are disturbed (EMI) , the smallest print line resistor and circumfluence of road of annulus of big electric current, and yuan of appropriate parts of an apparatus place, it is crucial. Graph the 6 commendation that showed manostat and exterior cell layout. This is PI3526-00-EVAL1 PI352x-00 is evaluated board adoption position.

Graph 6: Vicor ZVS manostat, inductor and the optimal layout that input and output capacitor. (picture origin: Vicor)

Graph 6 medium blue loop express to input and output capacitor (and VIN and VOUT) the close together method between, use at the tall AC circumfluence of manostat, help thereby extract high-energy effect.

Epilogue

To optimize the range of unmanned aircraft and laden ability, engineers had turned and use the tether of tall voltage. These measure utmost ground reduced the power dissipation in cable and voltage drop. However, tall tether voltage adjusts with respect to need safety and effective ground bus line voltage, reduce the power supply tension that without man-machine each electronic system place need further next.

Density and high-energy effect BCM are the high power of Vicor to reduce and promoted the voltage between earth station, tether and unmanned aircraft to offer a solution that achieves easily. These BCM have the aid of the ZVS step-down converter at low switch loss, in reach bus line voltage drop what without man-machine each subsystem needs 3.3, 5 with voltage of 12 bend over when, can effect is to be as high as 97% more.

(Author: Steven Keeping)

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