NO780875L - REVERSIBLE DRIVER FOR SUBMARINE VESSELS - Google Patents

Description

Reversible propulsion device for underwater vessels

The invention relates to a reversible drive device in accordance with the preamble of the main claim.

In DTS 176346 there is described a direct current drive device for water vessels where instead of mechanical switches such as e.g. is used according to DTAS 1203634, thyristors are used. This makes it possible to eliminate significant disadvantages of known road installations, namely strong coupling noise and limited service life. The direct current motors in these drive systems are fed from direct voltage sources, e.g. batteries, and with series and/or parallel connection it is possible to set several speed steps.

For braking operation of a drive device according to DTAS 1203634, it is firstly possible to reduce the number of revolutions by regenerative braking in the fourth quadrant, as the direction of the torque is changed. A feedback to the battery can thus take place. During the generator braking, the current direction in the DC motor's armature is changed. A beneficial braking is then obtained by returning energy to the battery as soon as a driving external torque causes the rpm to rise above the idle value or the field is strengthened.

Secondly, a reduction in the number of revolutions can be achieved with resistance braking or also short-circuit braking in the fourth quadrant. In this case, the motor's armature circuit is separated from the battery and connected to a load resistor.

Direct current drive systems with electronic switches allow, due to, su disses: valve action, no useful regenerative braking, as it is not possible to reverse the armature current. For such systems, therefore, only resistance braking is taken into account.

Stoppage and changeover times are relatively long with the above-mentioned plant layouts, which will be shown in the following:

Based on the number of revolutions equation, the armature current IA is obtained;

Where U = Armature voltage

R, = Armature resistance

A

n = Number of revolutions

0 = Flux

Here, the engine speed roughly corresponds to the propeller, so

n^n . The equation shows that the current I, disappears when the electro-prop

motor force c*npr0p-0n^- r the magnitude of the clamp voltage UAand changes direction when the electromotive force rises above the clamp voltage Us

Since, however, the braking effect on the ship in both cases ~ useful braking and resistance braking - in the fourth quadrant is weak due to the low propeller pressure and the engine's torque M, likewise becomes smaller with decreasing drag speed of the propeller, the product of torque and speed M, .n _ , .... , ._y___ 3 ^ d prop - that is, Isen fell off the given effect - likewise little, so only a weak stopping effect is obtained (also compare the Robinson curve). The turnaround times for such drive systems are therefore relatively long, based on experience 15 to 20 seconds.

The task underlying the invention consists in providing a reversible drive device with which it becomes possible to achieve short stop and changeover times by directly reversing the number of revolutions.

To solve this problem, the invention provides instructions that by issuing a stop command from a higher speed step after demagnetizing the motors and paralleling the direct current sources, a series connection of the motors with their starting resistance is made and a negative magnetization is applied to the motors, during which each motor and the associated starting resistance is shunted with a freewheeling diode.

Further designs of the invention are characterized

in the sub-requirements.

The drive device according to the invention is associated with several advantages. Thus, an emergency stop of the ship becomes possible, because it becomes possible from each speed step for forward direction to switch back via speed step I and on to higher speed steps for backward speed. The resistors needed for the start are also used for stopping and, due to the short changeover times, do not need to be significantly increased. The same applies to freelø<p>sdiodené. A normal stopping maneuver can also be carried out because in speed step I it can be adjusted back so that in reinforced fields it can be driven at a lower rpm in the backward direction. Finally, the electronic switches are not loaded more during the braking process, as part of the armature current makes its way through the freewheeling diode.

Further explanations will be given in connection with a design example which is illustrated by connection diagrams in the drawing.

Fig. 1 shows the layout of a facility.

Fig. 2 shows an example of the motorized resistance braking.

Fig. 3 shows a device with split starting resistance.

Block B contains the DC voltage source with the switching devices for parallel and series operation. It should, for example, include four sub-batteries. Block B is connected with its positive and its negative pole to busbars P and N, respectively.

For . speed step I, all partial voltage sources are connected in parallel. The electronic switch Sl, whose anode is connected to the positive busbar P, is lit, and the same is the case with the electronic switch S3, whose cathode is connected to the negative busbar N. The current then passes through the switch Sl, the series resistance RVl, the motor armature Ml, the diode D3, the motor armature M2, the series resistor RV2 and the switch S3.

For speed stage I, the motor armatures are connected in series. If operation is to continue* at this speed step I after start-up, switches S2 with the anode connected to the P rail} and S4 (with the cathode connected to the N rail) are switched on and switches Sl and S3 are switched off, so that the motor current now flows from the positive busbar P over the switch S2, the motor armature Ml, the diode D3, the motor armature M2 and the switch S4 to the neutral busbar N. The resistors are thus disconnected from the armature circuit.

At speed stage II, the partial voltage sources are still connected in parallel, the electronic switches Sl and S3 are lit, and likewise the thyristors T2 (with anode connected to the P rail) and Tl (with cathode connected to the N rail, A partial current then passes through the thyristor T2, the motor armature M2, the series resistor RV2 and the switch S3. Another partial current passes through the switch Sl, the series resistor RV1, the motor armature Ml and the thyristor Tl. The motor armatures are thus connected in parallel. If operation is to continue at speed level II, the series resistances RV1 and RV2 are disconnected from the two motor armature circuits at switching on the switches S2 and S4 respectively and switching off the switches Sl and S3 respectively.

For speed level III, all partial voltage sources are connected in series

and the motor armatures likewise driven in series via the victory resistors RVl and RV2. During continued operation at speed level III, the series resistors RVl and RV2 are disconnected from the motor's armature circuit t

For speed stage IV, the partial voltage sources remain connected in series,

while the motor armatures are switched to parallel operation via the series resistors RVl and RV2. During continued operation at speed level IV, the series resistances RVl and RV2 are then disconnected from the motor armature circuits.

A change in the number of revolutions at the individual speed steps takes place

by changing the magnetizing current with the help of a magnetizing current regulator 10 with associated comparison link 9. Both magnetizing windings El and E2 are supplied in parallel by the same magnetizing device 12 via a common weighting resistor 8.

The measured value of the magnetizing current is extracted from the weighting resistor 8 to be supplied to the measured value channel of the comparison link 9. Signals for the desired value are pre-supplied to the comparison link 9. The difference IE between the desired value and the measured value is fed to the input of the magnetizing current regulator 10, and its output signal constitutes the setting variable V - pø for changing the flux 0 in the magnetization windings El and E2. However, this signal UF is first supplied to a limiter 11. A signal proportional to the armature current is taken out on the series resistor RV2 and is likewise supplied to the limiter 11. When the permissible limit value of the armature current I , it causes with the armature current proportional signal that the setting quantity FØ can no longer be changed to higher values even if the desired value at comparison point 9 is increased.

From speed stage IV - partial voltage sources in series, motor armature connected in parallel, series resistors RVl and RV2 short-circuited - i.e.

from full speed ahead, there must now be a stop. For this, it is connected back to speed level I, which means all sub-batteries connected in parallel, motor armatures in series with the associated series resistors, the motors' EMF negative. The possible versions of the stopping maneuver will be illustrated by calculation examples. The rain sizes are standardized here, that is

referred to nominal values. Furthermore, the calculation will for simplicity

rf» -—-must be stated for an engine (or part engine).

The basis for the first calculation example is the regulation in requirement 2.

The electronic switches Sl to S4 are calculated for 1.6, nominal

current. The starting point is the nominal calculation quantities:

To illustrate the stopping maneuver, fig. 2. RVl must include the internal resistance of the motor armature so that RVl becomes equal to RVl = RV1+RA =0.24.

As four sub-batteries are connected in parallel, the voltage is U

f\ G li a quarter of the full tension, i.e. 0.125. In A, the limit value dimensioning at the series resistance RVl is limited to IA = 1.6.

The permissible values for the motor EMF are then obtained from the basic equation.

After switching to stop and prior delivery of a negative rnagn-: etization - ø, a propeller revolution number of e.g. n^^p = 0.5 is obtained. This is obtained from equation (1) for the flux 0: e = c-n. Ø._e rt 0 , 259 ^'c-0.5 c ? n • and the torque becomes according to the basic equation

If the propeller speed drops further, the torque can be increased. Since IA according to equation (1) is limited to 1.6 and e = c-n* 0 when increasing the flux can be kept constant corresponding to the used limiting regulation according to fig. 1, the torque Md = c• I- 0 increases according to equation (3) with increasing flux 0.

The second example is based on the version according to

requirement 3: If, by narrowly dimensioning the electronic switches Sl to S4, no large overhang of the current during braking operation can be allowed, precautions can be taken to still obtain a strong braking effect. As fig. 3 shows, the series resistance RVl is composed of partial resistances RVla and RVlb, so that at a division point P a division of the armature current IA takes place into 11+12. The braking process will again be illustrated by a calculation example. The strongest permissible current for the switches is 1.1, the damage limit for the motor, on the other hand, is 1.9. The armature current IA will therefore be able to amount to 1.9, while the current through switches S1-S4 must not exceed 1.1 (IA = 1/9; UA= 0.125;

RVla+RVlb = 0.24).

Thus the EMF values are:

for the size of the partial resistance RVlb is then obtained according to equation (5) at a limit value 1^= 1.1:

and RVla must stay

RVla = RVl - RVlb = 0.24 - 0.114 = 0.126

so the electromotive force according to equation (4) becomes

e = c-n-0 = IA . RVla = 1.9- 0.126 = 0.239

and the flux

Thus, according to equation (3), a torque is obtained

In this case, the magnetization must be adjusted corresponding to the motor limit value of 1.9 so that a signal magnitude proportional to the current is taken out across the resistor RVla, which is then fed to the limiter 11.

The basis for the third calculation example is the version according to claim 4. In this connection, reference is made to fig. 2. In this case the battery is separated from the driving circuit. The limit value for I, amounts to 1.9- The series resistance RVl = 0.24- - EMF e = I,. RVl* thus is

When one is reduced to 0.5, 0 is obtained for the flux

Prop

and for the torque

If the propeller speed is further reduced, e.g. to 0.2, the flux 0 would be:

if the flux 0 was not limited to 1 in this case, then the electromotive force must not become too great and the resistance RVl must not be increased. Thus, with a magnetization flux equal to 1, only one EMF can be obtained and IA is limited to

At a lower armature current limit of IA = 1.2, the limiting regulation would even allow a flux 0>1 even at greatly reduced propeller revolutions without it being necessary to increase the energy absorption in the series resistance RVl. With a limit value IA = 1.2 and constant resistance value 0.24, the magnetization at a propeller revolution number nprop= 0.2 could be increased to 1.44> 1:

The torque Md would then be

Claims (4)

1. Reversible drive device for watercraft with direct current motors that are fed from direct voltage sources, and where the individual speed steps can be set by series and/or parallel connection of the direct current motors and the direct voltage sources by means of electronic switches, characterized in that when of a stop command from a higher speed step, after demagnetizing the motors and parallel connection of the DC coils, a series connection is made of the motors with their starting resistors and a negative magnetization is applied to the motors, at the same time that each motor and the corresponding starting resistor are shunted with a freewheeling diode. 2. Drive device as stated in claim 1, characterized by a regulation of the negative magnetization so that the armature current IA forced by the direct voltage sources and the negative motor EMF remains below a permissible maximum current value I (I < I ). max gr max 3. Drive device as stated in claim 1, characterized in that the free-wheeling diode shunts the motor and part (RVla) of the starting resistance (RVl). 4. Drive device as specified in claim 1, characterized by a motor resistance braking in the fourth quadrant by separating the direct current sources from the drive circuit and magnetizing the motors depending on the permissible limit value of the armature current when reversing the field (-0).