JP2003506998A - Demagnetization protection type permanent magnet excited ship propulsion system - Google Patents

Abstract

(57) Abstract: A permanent magnet-excited electric motor cooperating with at least one rotational energy load (especially a ship propeller), a power conversion device for supplying energy to the electric motor, and a control, adjustment and monitoring device for the system In an electric drive system for high power (for example, power of 500 kW or more) having high availability and long life especially for marine vessels, the electric motor is configured to operate reliably for a long time, It is designed to protect against partial demagnetization, which is achieved by means of structural and operating technology, such as circuit technology and control technology, for the motor and the power converter.

Description

Detailed Description of the Invention

The present invention relates to a permanent magnet excitation electric motor cooperating with at least one rotational energy load (in particular a ship propeller), a power converter for supplying energy to the electric motor, and control, regulation and monitoring of the system. A large output (e.g., output of 500 kW or more) that has a device and has high usability and life especially for nautical vessels
Electrical drive system for a vehicle.

Permanent magnet excitation type motors have been known for quite some time with different structures. Different structures for permanent magnet excitation motors are described, for example, in the publication "Siemens-Zeitschrift" (Vol. 49, 19).
1975, No. 6, pp. 368-374). The achievable output at that time was up to 500 kW. For a long time this was the output limit of permanent magnet excitation electric machines, but only recently have large machines, for example up to 30 MW, been developed. For this type of machine, which requires considerable investment, long life and high availability were required to justify the investment costs. Ships are generally 25
It has a life of up to 30 years and therefore requires the same life for its propulsion device. This type of life has not been assured in the past for large permanent magnet excitation motors.

The object of the present invention is to provide a system in which a long life of this kind of large permanent magnet excitation motors is guaranteed reliably.

[0004] The problem is that the electric motor is designed to operate reliably for a long time, in particular to protect against complete or partial demagnetization, which is a structural and operational technical aspect of the electric motor and the power converter. , Which is achieved by means of circuit and control techniques, for example.

Permanent magnet life is an important criterion for motors designed according to structural rules for long life. Drive systems operating with permanent magnet excitation for ships or other large electrically driven installations (ships can also be considered industrial installations) have their life largely determined by the life of the magnetic components. Demagnetization can occur, for example, due to overheating or too large an internal magnetic field. Further, the magnets may be corroded and demagnetized due to aging. Movement of the magnets on the rotor of the electric motor can occur, for example, when high ambient acceleration occurs during a disturbance. The drive system according to the present invention takes into account the above-mentioned factors that reduce the life.

Regarding the demagnetization of the permanent magnet excitation type electric motor, the undergraduate graduation thesis “High-power type permanent magnet drive type electric motor” by Ville Nakli of the Faculty of Electrical and Communication Engineering, Helsinki Institute of Technology (February 14, 1998) ) Is also described. In this undergraduate thesis, it is shown that the temperature in the electric motor is within dangerous values, but the magnetic field can create a danger to permanent magnets in the event of malfunction of the electrical system. The solution to this problem cannot be achieved without considering other system components and is not shown in the undergraduate thesis.

In an embodiment of the invention, a permanent magnet of a magnetic alloy that is magnetically aging-resistant, for example based on sintered and heat-treated neodymium-iron-boron, is provided, which permanent magnet is particularly suitable for motors. It is fixed to the rotor by fitting and coupling. Such magnetic alloys have been known for some time, for example, by small electric drives for actuators. Its life characteristics have been thoroughly investigated practically and theoretically. The results of this study show that, if used as specified, a lifespan clearly exceeding the required time of 25-30 years is obtained. The prerequisite for this is the constant position of the magnet. The magnet must not move.

In another embodiment of the present invention, the electric motor is constructed without cooling by a reflux cooling type cooling medium, and particularly when used as a motor for a ladder propeller in an electric motor gondola, the outer wall of the gondola is cooled. . With this advantageous embodiment, maximum protection against overheating is achieved. Since there is no coolant circulation system,
This coolant circulation system will not fail. Outer wall cooling works well under all circumstances, especially for ship gondola drives. When the ship is running,
The movement of the drive ensures water cooling. The cooling effect increases with the speed of travel, ie with the energy consumed in the drive. In that case, a cooling which is responsive to the output occurs automatically.

In another embodiment of the invention, the magnetic circuit of the drive system is designed such that at the rated point the short circuit current is automatically limited to a non-hazardous value. The short-circuit current, which is due to, for example, a terminal short circuit, is 1.7 times the rated current in a standard application. This value is not dangerous. For example, the magnet system according to the invention is
This is because the magnetic field generated by the overcurrent can withstand 2.2 times the current without damaging the permanent magnet. In the power converter, for example, 110% to 120% of the set current
A current limit is applied to the current limit and the current limit is parameterizable. In connection with that current limiting, it is ensured that the current flowing everywhere through the motor is limited to a non-hazardous value. For this purpose, the power converter has, for its individual arms, a maximum current limit, for example to a value that reliably prevents demagnetization due to overcurrent, which maximum current limit is parameterizable. By including the individual arms of the power converter and the power converter as a unit in the monitoring mechanism, even in the unlikely case, the current in all parts of the motor is limited to a non-hazardous value. can do.

It is particularly advantageous to use a current limiter, for example an HTSC current limiter, which cuts off very fast on the basis of physical action, eg in less than 1 ms. HTSC (High
The Temperature Superconducting (current superconducting) current limiter operates at about 77K, ie cooling with liquid nitrogen. Immediately after the dangerous current density is exceeded, a relatively large finite resistance is created, i.e. a primary cut is made. In that case, after a short time, for example, a secondary disconnection by a power breaker is required.

The current limiter of the 1 MVA class has been already announced by the applicant of the present application. The YBCO layer of the ceramic plate-shaped conductor acts as a switch element.

The current limitation is based on various power semiconductor elements (depending on the configuration of the power converter).
For example, GTO, IGBT, thyristor) can be used in a special form. It is advantageous if the power semiconductor components are individually monitored in order to be able to immediately detect the semiconductor component having the short-circuit fault and to replace it. Therefore, a short circuit of the used power semiconductor components, which should not be completely eliminated, does not damage the magnet system.

In order to monitor the drive system, furthermore, between the power converter and the electric motor and between the power converter and the transformer for the power converter, both for the entire power arm and for the individual power arms. However, the measuring device is arranged. Faults in the power converter are thereby detected and eliminated at high speed. For the detection, known measuring devices are provided which correspond to the detection.

It is particularly important that the current limiter is related to the motor speed. Thereby, the fact that the internal magnetic field is related to the motor speed is taken into account.

Other protective measures are provided by ground indicators and ground guards for ships, lead breakage monitors, phase symmetry monitors and other monitoring and protection circuit components, especially against overcurrent and overheat. The motor is monitored for any failure of the entire system.

In another embodiment of the invention, the electric motor is provided with a multi-winding system having two power converters each of which feeds a winding, or the two drive motors each have one power converter. Working together with each other, the three phases of the power conversion device are connected to form a three-phase system. This forms a generally small unit that is individually monitored and cut. This likewise ensures that no harmful overcurrent is generated in the drive motor.

In particular, a remote diagnostic device is provided which diagnoses the ship propulsion system and diagnoses the power converter with its components. A remote diagnostic device of this kind operates, for example, in satellite communication with a ship and a manufacturer expert informs the ship engineer which components should be replaced or will soon fail. To be able to do. This also increases the demagnetization protection and the driving safety.

In order to guarantee the life of the permanent magnets, the permanent magnets are based on, for example, sintered and heat-treated neodymium-cobalt-copper-iron-boron, magnetic alloys resistant to magnetic aging and especially corrosion resistance ( For example, Vac quality Vacodynm 677HR). In addition, the permanent magnet is permanently retentively coated or lacquered and has a smooth surface. The permanent magnet has, for example, a rectangular parallelepiped shape. This produces a corrosion resistant matrix and provides a corrosion resistant overall construction.
Material losses of the permanent magnets, and thus magnetic losses, do not occur during the required life of the motor under the conditions imposed.

Advantageously, the magnet block is fixed to its base by means of an adhesive, in particular a fully reticulated silicone adhesive in the form of a one-component adhesive. The use of a fully reticulated silicone adhesive in the form of a one-component adhesive prevents the formation of corrosion sites at the transition between the magnet and the pole piece.

In order to monitor the electric motor, the stator windings are provided with a temperature sensor, in particular a measurement value evaluation unit and / or
Alternatively, it has a temperature sensor provided with an actuation unit for an alarm function. In that case, it is advantageous if a temperature sensor is connected to the control of the system in order to ensure that the windings and magnets are prevented from overheating. This creates additional monitorability which adversely affects the detrimental tendency of motor heating.

The attractive force of the individual magnet blocks is very high. In an advantageous embodiment of the electric motor, the diameter and the maximum speed of the electric motor are set such that at the maximum speed, a residual force is left between the rectangular parallelepiped magnet and its mounting surface (automatic permanent magnet retention). It Indeed, the magnet block is fixed to the base by snap-fitting and force-bonding in relation to the geometry of the pole pieces by means of the strips, whereas automatic permanent magnet retention makes this snap-in and force-bonding holding possible. It will be further strengthened. The rectangular parallelepiped magnet is reliably positioned without impairing its life and even when an excessive force is generated during a disturbance, for example. The strip can consist of fiber-reinforced plastic as well as of A magnetic material. However, the fiber-reinforced plastic allows a particularly thin construction of the strip, which constitutes an electric motor with a particularly small air gap.

Advantageously, the winding ends of the stator winding are cast and are connected to the outer wall via a solid, thermally conductive bridging piece. This provides a configuration that is certainly far superior to reflux cooling forced circulation cooling.

From a similar point of view, an electric motor configuration is obtained which has a closed outer case without openings. This prevents foreign matter from entering the electric motor from the outside during repair or the like. Overall, a maintenance-free construction of the electric motor with a closed structure and maximum life is obtained. The shaft between the ship and the gondola, which is known for permanent magnet excitation / reflux cooled gondola drives, can therefore advantageously be eliminated. Therefore, it is not necessary to repair the electric motor on the occasion of the ship being dogged for a total of 5 years, and only wear parts such as packing and bearings need to be inspected and replaced if necessary.

[0024] Finally, a magnetic field sensor is arranged in the motor to further improve the protection,
This is possible in particular on a periodic basis or is event-controlled.
Furthermore, for example, the measured values from the individual currents in the electric motor, the electric motor temperature, the emitted power, the number of revolutions and, if necessary, other influence quantities can be used to continuously determine the electric and magnetic state of the electric motor, and the dangerous value There is provided an arithmetic unit capable of issuing an alarm when approaching the vehicle, and in particular controlling in the opposite direction. This makes it permanently advantageous, especially for remote diagnosis, to carry out continuous monitoring of the drive motor, taking into account the reverse control of the individual influence quantities.

The present invention will be described in detail with reference to the drawings. As well as the dependent claims, other details important to the invention can be seen from the drawings. 1, 2, 3 and 4 are individual circuits provided for the system, FIG. 5 is a standard magnetic flux distribution diagram of a permanent magnet, FIG. 6 is a rotor length-temperature curve diagram, and FIG. 7 is a magnetic force characteristic. FIG. 8 shows time-magnetic force characteristics of neodymium-iron-boron magnets.

[0026] Each drawing should be understood by an expert as a matter of course from the detailed data and description contained in the claims in connection with the description of the claims.

In FIGS. 1 to 4, notations that are commonly used in the electronic technology of transformers, power converters, and electric motors are used. FIG. 1 shows a three-phase machine with one 6-pulse power converter, which has a minimum number of phases to be monitored and a minimum number of power semiconductor elements. Therefore, the individual monitoring of the phase and the power semiconductor element is selected here.

FIG. 2 shows a circuit diagram of a three-phase machine with one 12-pulse power converter. The number of power arms in the power converter is doubled. Here, the monitoring is simplified because it is performed on the power converter. In FIG. 3 as well, monitoring within the motor can be reduced. FIG. 4 shows the circuit of a 6-phase machine with two 12-pulse power converters and shows the optimum configuration for protection.

The idealized magnetic flux distribution shown in FIG. 5 is particularly characterized by its symmetry. That is, special magnetic flux concentration can be avoided.

FIG. 6 shows the stator temperature as a function of motor length. The rotor temperature is about 10 ° C. lower than the stator temperature, so independent monitoring of rotor temperature can be omitted. As is apparent, the air gap temperature on the excitation side of the motor is the highest and therefore the monitoring thermocouple is centrally located here.

By densely arranging the thermocouples densely on the magnet side of the electric motor, the electric motor temperature can be easily and surely monitored. Advantageously, the thermocouple is firmly coupled to the stator winding.

FIG. 7 finally shows the magnetic force under no load, under rated load, and under short circuit. Obviously, the magnetic force in each case lies within the reversible part of the characteristic curve, which also applies to short circuits. That is, demagnetization protection is performed even in the case of a short circuit.

FIG. 8 finally shows, in logarithmic representation, the irreversible polarization loss measured by close examination at 130 ° C. with different factors B / μ0H. 130 ° C. is considerably higher than the maximum temperature apparent from FIG. 6 in the motor according to the invention, i.e. the protection against demagnetization with respect to overtemperature is high, which makes the useful life of the magnet 25-30 years or more as required.

A transformer resin that has been tested over the years with a permanent heat resistance of 150 ° or more due to a good maximum emerging temperature of 90 ° and a permanent magnetic force in the permanent magnet range at 130 °. 25 to 30 years life expectancy for permanent magnet excitation drives of marine gondola motors, based on the use of (for which there is already more than 20 years of operating experience here) and the reliable avoidance of overcurrent in the motor windings. Is guaranteed. The failure-free closed construction using the direct outer wall cooling method contributes little to this.

[Brief description of drawings]

[Figure 1]   Circuit provided for the system

[Fig. 2]   Circuit provided for the system

[Figure 3]   Circuit provided for the system

[Figure 4]   Circuit provided for the system

[Figure 5]   Standard magnetic flux distribution diagram of permanent magnet

[Figure 6]   Rotor length-temperature curve diagram

[Figure 7]   Magnetic force characteristic diagram

[Figure 8]   Neodymium-iron-boron magnet time-magnetic force characteristic diagram

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H02K 15/02 H02K 15/03 Z 15/03 15/12 E 15/12 11/00 E (72) Invention Lutzatki, Wolfgang Germany Federal Republic of Germany -21509 Grinde Grothhagen 4A F term (reference) 5H604 AA05 BB01 BB10 BB14 CC01 CC05 PE06 5H611 AA01 BB01 BB06 PP02 PP05 QQ04 QQ05 UA02 5H615 AA01 BB14 PP01 PP14 BB01 PP14 BB01 PP14 BB01 PP14 PP14 SS57 TT05 TT26 5H621 BB10 GA01 HH01 JK01 JK11 JK14 5H622 AA04 CA02 CA10 DD02 PP03 PP19

Claims (33)

[Claims] 1. A permanent magnet excitation electric motor cooperating with at least one rotational energy load, in particular a ship propeller, a power converter for supplying energy to the electric motor, and a control, regulation and monitoring device for the system. In an electric drive system for a high power, for example 500 kW or more, which has a high usability and a long life especially for a sailing ship, the electric motor is configured to operate reliably for a long time, and particularly, a complete or partial operation. Electrical drive system which is configured to protect against demagnetization, which is achieved by structural and operational engineering, for example circuit engineering and control engineering, means for electric motors and power converters. . 2. A permanent magnet, for example based on sintered and heat-treated neodymium-iron-boron, made of a magnetic alloy resistant to magnetic aging, the permanent magnet being especially fitted to the rotor of an electric motor. The drive system according to claim 1, wherein the drive system is fixed by mating connection. 3. The electric motor is configured to operate without cooling by a reflux cooling type cooling medium, and particularly when used as an electric motor for a ladder propeller, an outer wall of the gondola is cooled. The drive system according to 1 or 2. 4. The drive system according to claim 1, wherein the magnetic circuit is designed such that at the rated point the short-circuit current is automatically limited to a non-hazardous value. 5. The power converter limits the current in the windings of the motor to, for example, 110% to 120% of the set current, the current limit being parameterizable. The drive system according to any one of 1 to 4. 6. The power converter has a maximum current limit for its individual arms, for example to a value which reliably prevents demagnetization due to overcurrent, which maximum current limit is parameterizable. The drive system according to any one of claims 1 to 5. 7. A method according to claim 1, further comprising a current limiter, such as an HTSC current limiter, which cuts off very fast based on physical action, for example less than 1 ms. Drive system. 8. The drive system according to claim 1, further comprising an IGBT power semiconductor element having an automatic high-speed disconnection means in case of malfunction. 9. The drive system according to claim 1, further comprising a thyristor whose function is monitored. 10. The drive system according to claim 1, wherein an individual phase current measuring device is arranged between the power converter and the electric motor. 11. The drive system according to claim 1, wherein the phase current measuring device is arranged between the power converter transformer and the power converter. 12. A method according to claim 1, wherein current limiting is performed in relation to the speed of the electric motor and, if necessary, the torque of the electric motor, and the current limiting is parameterizable. The described drive system. 13. A drive as claimed in claim 1, characterized in that a power switch, which can be switched under load, is arranged between its supply and the power converter transformer. system. 14. The drive system according to claim 1, further comprising a grounding indicator and a grounding protection device for a ship. 15. The drive system according to claim 1, further comprising a conductor breakage monitoring device. 16. A drive system according to claim 1, further comprising a phase symmetry monitoring device. 17. A drive system as claimed in claim 5, characterized in that other monitoring and protection circuit components are provided, in particular against overcurrent and overheat, as well as controllers and regulators. 18. An electric motor is provided with a multi-winding system having two power converters each feeding a winding, each three phases being connected to one three
18. The drive system according to claim 1, wherein a phase system is formed. 19. A drive system according to claim 1, further comprising a remote diagnostic device for diagnosing a ship propulsion system, in particular for diagnosing a power converter together with its components. 20. A permanent magnet is provided which is made of a magnetic alloy which is magnetically aging-resistant and in particular corrosion-resistant, for example based on sintered and heat-treated neodymium-cobalt-copper-iron-boron. The drive system according to claim 2. 21. As a permanent magnet, a permanently retentively coated or lacquered magnet block, in particular a permanently retentively coated or lacquered magnet having a rectangular parallelepiped shape. 21. Drive system according to one of the preceding claims, characterized in that a block is provided. 22. Drive according to claim 21, characterized in that the rectangular magnet is fixed to its base by means of an adhesive, in particular by a fully reticulated silicone adhesive in the form of a one-component adhesive. system. 23. The stator winding comprises a temperature sensor, in particular a temperature sensor with a measured value evaluator and / or an actuator of an alarm function.
Drive system according to one of 24. Drive system according to claim 23, characterized in that a temperature sensor is connected to the control part of the system in order to prevent overheating of the winding and / or the excitation magnet. 25. The diameter and the maximum rotation speed of the electric motor are set so that a residual force is left between the rectangular parallelepiped magnet and its mounting surface (automatic permanent magnet holding) even at the maximum rotation speed. Drive system according to one of the claims 1 to 24, characterized in that 26. A stator of an electric motor is enclosed in its case together with its windings, the winding end region of which has a solid heat-conducting bridge, in particular made of plastic, for example epoxy. The drive system according to claim 3, wherein the end portion itself is cast with an insulating resin. 27. The excitation magnet is formed in a particularly rectangular parallelepiped shape, is arranged on a pole piece having a polygonal surface, and is fixed to the polygonal surface by means of a strip from the outside. 27. A drive system according to one of 26. 28. Fiber-reinforced plastics in the form of strips, in particular glass fibers,
8. A drive system according to claim 7, characterized in that the strip comprises carbon fibers or plastics reinforced with Kefler, the strips having in particular pre-impregnated fibers in the form of strips. 29. Drive system according to claim 28, characterized in that the plastic is a class F insulating plastic, in particular a filled transformer resin. 30. The drive system according to claim 1, wherein the exciting magnet has a strip band made of an A magnetic material, for example, stainless steel. 31. The drive system according to claim 1, wherein the electric motor has a closed outer case having no opening. 32. Drive system according to claim 1, characterized in that a magnetic field sensor is provided in the motor, in particular a magnetic field sensor which is switchable periodically or which is switchable under event control. 33. The electrical and magnetic characteristics of the motor in a continuous manner, taking into account individual quantities, for example individual currents in the motor, winding temperatures, emitted power, rotational speed and, if necessary, other influence quantities. 33. A drive according to claim 1, further comprising an arithmetic unit capable of obtaining a state by arithmetic technology, issuing an alarm when a dangerous value is approached, and controlling in the opposite direction in particular. system.