DE3242426A1 - Central on-board network supply system on aircraft - Google Patents

Abstract

An external on-board network supply system supplies the loads of the aircraft when it is on the ground for the purpose of servicing, having a three-phase line voltage of 208 Volt and a phase voltage of 117 Volt at 400 Hz. In order to compensate for the voltage drops which occur and to maintain the individual phase voltages continuously at the nominal value even in the case of asymmetric load, each phase voltage has an auxiliary voltage allocated to it in such a manner that the voltage vectors add to or subtract from the required nominal value. These auxiliary voltages are supplied via rotating transformers which are operated by actuating motors and are connected to the respective phase voltage. The rotating transformers are set as a function of error signals, in the sense of reducing the errors to zero.

Description

Central on-board power supply system at airports

The invention relates to an on-board power supply system of in the preamble of claim 1 specified genus. External on-board supply systems are also required at airports to service aircraft parked on the ground to be able to. Here it is for reasons of economy and also for reasons of Noise protection inexpedient, the consumers of the aircraft through the on-board system to be supplied either via gear assemblies from the main engines drive yourself or via a small auxiliary power unit that is only used for supply allow.

While in the past only diesel-electric units were used that were brought to the location of the parking area of the aircraft in question have become increasingly central, especially at large airports On-board power supply systems specified in the preamble of claim 1 Type by which are more economical than the diesel aggregates, what in terms of on the required power, which can amount to around 70 to 100 kVA is.

Problems arise with such central on-board power supply systems especially with regard to the required line length between central Generator, which is usually driven by an electrical machine, and the On-board network connection station at the gate. The length of the lines can be several 100 m. Due to the relatively high voltage used for the transmission path, the ohmic Losses are kept relatively low. With regard to the transmission cables adherent inductance, which is also asymmetrical is surrender at the required frequency of 400 Hz already serious problems. It is known to determine these inductances on site and by switching on to compensate for capacitor batteries.

It is also known to avoid the undesirable inductive voltage drop Use induction-free cables. Such cables are extremely expensive.

The invention is therefore based on the object of providing a central on-board power supply system to create that while avoiding expensive induction-free cables or capacitor batteries is able to use the vehicle electrical system independently of symmetrical or asymmetrical load conditions to be constantly supplied with the required voltage, even when the load changes is maintained.

The task set is solved by the one in the labeling section of claim 1 specified features.

The regulating transformers used here only need a relative low power to be designed, so that the main transformer in terms of its translation ratio can be interpreted firmly and at this the full The power-transmitting transformer is not provided with any adjustment or control arrangements Need to become.

The provided rotary transformers enable a practically stepless Voltage change to the desired actual value and they are therefore for the specified Regulatory purpose to prefer. In principle it would of course also be possible the use of step transformers for this purpose, which can be switched accordingly are.

The arrangement is expediently such that the secondary winding of the control transformer is switched so that the voltage is in phase with the assigned Phase voltage is such that the voltage vectors add up. It then becomes the Main transformer designed so that the secondary voltages are slightly below the nominal value lie, the control range of the control transformers is chosen so that all Voltage drops that are conceivable during operation can still be detected. It has shown, that a control range of 15 volts per phase is sufficient for this.

Instead, the arrangement could also be made such that the voltage vectors in the phase winding and in the secondary winding of the regulating transformers are directed in the opposite direction, so that regulation takes place from above, but it is off to prefer the former arrangement for various reasons.

With the invention, the demand made is fully met, according to which the voltage drop must be less than 3%. Because the Phase voltages are regulated individually, results even with asymmetrical loading constant adjustment to the desired target voltage. This allows all voltage changes be balanced, regardless of whether they are based on a real component or a blind component are based. If necessary, however, the reactive component can also be known per se Way to be compensated on the generator side, by either capacitive Loads can be switched on or a synchronous machine that is not required in each case a central generator system by corresponding over or under excitation sets cos-t value to 1.

Further expedient refinements of the invention emerge from the subclaims and in conjunction with the accompanying drawings. In these Drawings show an embodiment of the invention.

The drawings show: FIG. 1 an overall circuit diagram of an inventive device trained central on-board power supply system; Fig. 2 is a block diagram of the Regulator; Fig. 3 is a circuit diagram of the effective value generation stage of the controller according to Fig. 2; Fig. 4 is a circuit diagram of the controller stage for a phase, of which for each Phase one stage is provided for each phase.

In Figure 1, a three-phase voltage generator G is shown, which is connected to a central point of the airport and for example 100 kVA at 400 Hz supplies. Depending on the size of the airport, there is one generator or there are several Generators provided. Each one supplies a voltage of 3 x 820 V concatenated.

From the generators G each lead three phase lines and Neutral conductor after a main transformer HTR, one of which is connected to each a board network connection station is arranged. The primary winding and the secondary winding these main transformers are star-connected. The secondary phase windings of the main transformer are labeled P1, P2 P3. In Figure 1, the connector is with which a plug connection is made to the electrical system of the aircraft in question can be referred to as AS. Here are the outputs of the three phases as well as the Neutral conductor accessible.

The secondary winding is connected to each of the secondary phase windings P1, P2, P3 51 '52 S3 of regulating transformers TR1, TR2, TR3 in series. The primary winding each Control transformer is connected to a rotary transformer DT1, DT2 or DT3. These in turn are fed with the respective phase voltage. By having the Rotary transformers a voltage can be added to the phase voltage, the nominal voltage can be continuously adjusted even if the load changes reach. According to the illustrated embodiment, the voltages are from Phase winding and secondary winding of the regulating transformers added. If necessary however, a switchover can also be made in such a way that optionally one Subtraction takes place.

Finally, the rotary transformers could also have a center tap be provided, which enables regulation on both sides.

The rotary transformers are driven by servomotors Mr M5, Mt from a Controller 10 is set to which the actual voltage supplied via lines 12 and in which these actual voltages are compared with a nominal voltage.

This controller 10 is fed from the 50 Hz network.

Figure 2 shows a block diagram of the controller. This has an effective value extraction stage Pl1 and three controller stages Pl2, Pl3 and Pl4, of which the latter one each each assigned to a phase.

The circuit of the rms value generation stage Pl1 results in detail from Figure 3. The inputs and outputs are uniform in the various representations specified.

Figure 4 shows the circuit diagram of one of the controller stages Pl2, Pl3 or Pl4. These three controller stages are identical to one another, so that the description a single stage according to Figure 4 is sufficient.

Each regulator stage has a first comparator 14, a second comparator 16 and a third comparator 18. All comparators are on line 20 is supplied with a setpoint voltage, while the actual voltage is supplied via 22.

The comparator 14 detects an error signal between the target voltage and an underlying actual voltage and it causes the output to control the servomotors Drive Mrs. M5, Mt in the sense of a voltage increase.

The comparator 16 detects an error between a target voltage and an actual voltage above it and it causes a voltage reduction.

The comparator 18 detects the de-energized state and it effects when the network is switched off, the servomotors are shut down to prevent that unnecessarily the comparator 16 in each case the associated rotary transformer returns to the zero position. This ensures that when the unit is switched on again the previously and last regulated voltage is available again.

According to the illustrated embodiment, the controller acts as a two-point controller. If necessary, however, other control characteristics, in particular an aperiodic approach to the setpoint can be guaranteed.

Galvanic isolation between the 400 Hz network and the 50 Hz network takes place via optocoupler 24.

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Claims (5)

Central on-board power supply system at airports Patent claims: Central external on-board power supply system at airports, with one or more central three-phase generators, which e.g. 3 x 820 volts linked voltage with a Supply frequency of 400 Hz, with individual line connections between the central Generator and each on-board network connection station and with a transformer in each On-board network station that converts the supply voltage to the consumer voltage of around 208 Volt chained lowers, characterized in that it is in series with each phase winding (P1, P223) the star-connected secondary side of the transformer, the secondary winding (S1, S2, S3) of a regulating transformer (TR1, TR2g TR3) is connected, the primary windings of which are each fed by a rotary transformer (DT1, DT2, DT3), which is connected to the respective Supply voltage are switched on and of servomotors depending on a Error signal can be controlled. 2. Berdnetzversorgungsanlage according to claim 1, characterized in that that the phase voltages on the secondary side of the transformer are one below the nominal phase voltage of 117 volts lying voltage of about 112 volts, and that the transmission ratio the regulating transformers (TR1; TR2; TR3) in connection with the rotary transformers is designed so that a control voltage V from 0 to +15 volts is available in phase is provided. 3. On-board power supply system according to claim 1, characterized in that that the controller setting the servomotors (M ,, M, M $ is fed by the 50 Hz network and is galvanically separated from the 400 Hz part by optocouplers. 4. Control circuit for an on-board power supply system according to claim 1 characterized in that this is the difference between the target voltage and the actual voltage forming error signal is fed to three comparators, which via a control circuit control the servomotors and of which the first in the sense of a voltage increase and the second is effective in the sense of a voltage reduction, while the third Comparator brings about a shutdown of the servomotor in question when switched off of the generator network, the fault voltage exceeds a predetermined value. 5. Control circuit according to claim 4, characterized in that the Measurement phase voltages are fed to a stage (Pl1) for effective value acquisition, which is fed by the 50 Hz network and whose output is assigned to the individual controller stages (Pl2fPl3Pl4) each of which is equipped with the three comparators.