Since the boom of the NdFeB magnets industry, the usage and potential applications for permanent magnet machines have grown exponentially to the detriment of traditional induction systems. In special applications like elevators, cranes, hybrid vehicles or renewable energy, permanent magnet machines have already become the preferred technology. In the marine sector, they are now starting to be the main competitor to mainstream solutions.
Permanent Magnet Materials for Electrical Motors
The development of permanent magnet materials has progressed quickly during the past few decades. First, the materials were based on cobalt-tungsten-chromium iron alloys. Aluminium-nickel-cobalt alloys were discovered in the 1930s, but the development of samarium-cobalt in the 1960s, and finally neodymium-iron-boron based magnets (NdFeB magnets) in the late 1970s, made it possible for electrical motors to benefit from permanent magnet materials.
Ever since, NdFeB magnets have been generating a great amount of interest among leading industrial players, thanks to their high level of energy density as well as other useful material properties, like corrosion resistance and temperature tolerance. In particular, the large remanence and coercivity of SmCo and NdFeB magnets have led to the application of these materials in industrial motor and generator drives.
Although standard induction machines (IM) have ruled the electric machine business for years, the exceptional possibilities offered by NdFeB magnets have led to a consistent, spectacular growth of their production and utilization around the world.
Improving Efficiency
A synchronous PM machine contains Neodymium-Iron-Boron (NdFeB) magnets, which are materials with a very high flux density. This makes them ideal for variable-speed motors and generators throughout the entire speed range, significantly cutting back on fuel consumption. A PM machine is typically 2–4% more efficient at full load and 10% more efficient at part load when compared with induction machines. These efficiencies result from a lack of current losses in the rotor, the absence of an exciter and reduced winding losses.
Induction machines have relatively good performance above ~1000 rpm, but are typically not very good at low speeds due to increasing rotor losses based on the relative slip of the rotor. This slip is dependent on the torque.
As an example, where a 50 rpm slip with constant torque means, at 3000 rpm, only a 1.7% relative slip causing a ~1.6% reduction in efficiency, it represents a 17% relative slip at 300 rpm, dramatically reducing the efficiency by 17%. PM machines do not have slip and thus the “slip-loss” component of the rotor is non-existent. In high-power applications at 300 rpm, it is therefore possible to achieve efficiencies of about 98%.
Adjustable Speed Control
Besides high efficiency for a large speed range, the main reasons to select a PM machine are low speed and the need for speed control. To handle highly fluctuating load cycles, guarantee longer engine life, cut back on fuel consumption and reach lower exhaust values, adjustable speed control is ideal. The Switch integrates a frequency converter in the drive train package to offer the accurate and adjustable speed control needed for dynamic positioning and demanding load cycles in offshore and special vessels. This avoids the low or no-load running of generators, which minimizes engine heat stress, reduces fuel consumption and eliminates undesired start/stop engine cycles.
Using adjustable supply frequency also allows full speed control of the machine. Generally with 4Q control and an external cooling arrangement, the speed torque curve of a PMSM is a box (Figure 1) that covers the whole speed torque range.
Diesel Generators and Marine Propulsion
PM machines offer special seafaring vessels the opportunity to lower operational costs by optimizing the fuel consumption of the diesel engine. Ships often use diesel generators, not only to provide auxiliary power for normal consumption, but also indirectly for the main propulsion. There are two different main types of diesel engines: 2-stroke and 4-stroke. The main difference from the generator point of view is the rotational speed. The 2-stroke engine has a rated speed from 50 to 200 rpm, while a 4-stroke engine is typically above 500 rpm.
Two-stroke engines in marine are mainly used for propulsion. But as the power generation may be integrated into the main propulsion system, it has to apply the same speed as the main engine or the revolutions have to be raised with a step-up gearbox.
The Switch manufactures both direct-driven shaft generators in frame sizes of 1000 and 1500 and high-speed generators in frame sizes from 450–710. So-called shaft generators are direct drives built around the main propulsion shaft, which are part of the main propulsion line. High-speed machines (~1500 rpm) are connected to the propulsion line through the gearbox. In addition to power generation, machines may also be used for electric propulsion. In such cases, separate auxiliary generators produce the propulsion power. These auxiliary generators are typically 4-stroke diesel engines.
At the end of February, WE Tech Solutions placed orders for two PMM 1000 M shaft generators from The Switch with the option for an additional two to be used in future WE Tech Solutions projects. WE Tech Solutions utilizes the PM machine both as generator and motor in their direct-drive permanent magnet shaft generator solution. The solutions will be delivered by WE Tech to Besiktas Shipyard in Turkey for installation in two 15100 DWT asphalt carrier new buildings recently ordered by Canadian ship owner Transport Desgagnés. For this type of vessel, the ability to switch to the Take Me Home mode provides Auxiliary Propulsion Drive (APD) in the same package is key. The solution provides considerable fuel and service cost savings achieved from having the auxiliary generators turned off when in sailing mode.
PM machines are also known for their unmatched design flexibility. Thanks to the high power density, PM machines can pack more power in a package that is far more compact, lighter in weight and smaller in size compared with induction machines.
The Author
Mika Koli works as the Business Development Manager for Marine at The Switch. One of his main responsibilities is to help develop the advanced drive train technology for marine applications based on permanent magnet and frequency converter technology.
(As published in the May 2015 edition of Maritime Reporter & Engineering News - http://magazines.marinelink.com/Magazines/MaritimeReporter)
in the Clarion-Clipperton Zone (CCZ) in the Pacific Ocean (any mining interests in this area are managed by the ISA). They consist of manganese, nickel, cobalt and copper, and it’s estimated that in the CCZ alone, there is 1.2 times more manganese, 1.8 times more nickel, and 3.4 times more cobalt than in all
that shows test results of the alloy's resistance to sulfide stress cracking in sour wells. Nitronic 60 wears up to three times longer than high-cobalt alloys in oilfield applications but costs much less, the other bulletin says. Nitronic 60 can be used anywhere in oilfield equipment where metal meets
of mining manganese nodules from the Pacific Ocean floor at depths of 18,000 feet. The nodules composed of manganese, nickel, copper and cobalt of approximately 30 percent mineral composition with approximately 26 additional trace minerals are pebbled across the floor of the seabed to an average
implication of enormous importance. It opens the door to self-sufficiency f o r the United States in at least four essential minerals — manganese, cobalt, copper and nickel. The principal speaker at the 88th Annual Banquet of the Society was David S. Lewis Jr., chairman of the board and chief executive
cruises to plot and sample the rich nodule fields between the Hawaiian Islands and Baja California. The nodules contain manganese, nickel, copper, and cobalt, and are so abundant that known ocean deposits could last for centuries. Conrad G. Welling, OMCO vice presidentprograms, said: "Two types of areas
of the situation as it stands today. "The role of nodules in the world resource picture," he said, "represents a potential source of nickel, copper, cobalt, molybdenum and manganese. The magnitude of such deposits is sufficient to meet the nickel demands of the United States for over 100 years." It
over centuries, have been found 1,500 miles southeast of Hawaii. They contain approximately 25-percent manganese, and 3-percent nickel, copper and cobalt combined. Recent actions by the U.S. Congress relating to international "law of the sea" developments have been considered favorable to future manganes
over centuries, have been found 1,500 miles southeast of Hawaii. They contain approximately 25-percent manganese, and 3-percent nickel, copper and cobalt combined. Recent actions by the U.S. Congress relating to international "law of the sea" developments have been considered favorable to future manganes
end of April.Back on the U.S. side of the big pond, French oil major Total announced that it had acquired several assets in the Gulf of Mexico, as part of Cobalt International Energy’s bankruptcy auction sale. The deal, which was reported to have cost Total $300 million, involved a 20 percent stake in the North
of the resource has found what looks like 200 million tons of the polymetallic nodules. The trove is potentially also, “the largest known primary cobalt resource in the world.”AUV visuals: Swire Seabed’s user interface. Photo: Swire SeabedProven techniquesThe company says a 2016 multi-year
water within coastal states’ EEZs. These crusts form a hard pavement on the seabed up to 25cm thick. The minerals of commercial interest are cobalt, titanium, platinum and some rare-earth minerals (REM).Each of these types of deposits present their own unique challenges for effective and environmentally
inside a soft plastic pouch. This is known as a “prismatic cell”. There are several LiPo chemistries, but the most common for prismatic packs is Lithium Cobalt Ox- ide. The chemistry is speci? ed in the MSDS for that battery. A stack of prismatic cells maybe be bound together using a shrink wrap, for lightweight
operation would strip 8,000-9,000 square kilometers of seabed, leading to the possible extinction of species. In the second technique, when mining for cobalt-rich ferromanganese crusts, the out- er layer of seamounts is stripped, destroying sea sponge and coral. The third type of DSM, which focuses on hydrother-
hurdles to a this area are managed by the ISA). They consist of manganese, production ramp up of sustainable aviation fuels and the even nickel, cobalt and copper, and it’s estimated that in the CCZ longer-term pursuits of electric and hydrogen propulsion. alone, there is 1.2 times more manganese
, material and feature a high performance ing the ? ow, pressure and temperature of traceability and workforce accountabili- tooth material with extra Cobalt for en- the methanol to meet the engine’s spe- ty; and an unprecedented level of control hanced heat and wear resistance. These ci? c requirements
buoy-laying ves- Like Shift, Freyer has secured deals for future supplies of sel with two electric motors powered by 150 kWh batteries. lithium and cobalt cells from Asia (Japan), although a US JV Danfoss Editron, too, controls its system with “sophisticated with 24M will target 50 GWh of batteries
year for pendant on these critical minerals. 2023 subsea mining, “Remaining reserves of critical miner- both in Norway and internationally. als like Cobalt, Manganese, Nickel and Norway’s environmental impact assess- Copper can to a large extent be found ment for marine mining is ongoing, and under
bilities, the Filtree System also removes tering systems on MR tankers M/T Pa- ing a CO2 battery onboard. oil residue and particulate matter from ci? c Cobalt and M/T Paci? c Gold, with The charged CO2 battery will be dis- the wash water, ensuring its PH value is an option to equip three more vessels.
WORKBOAT SEISMIC SURVEY VESSELS per, cobalt, nickel, and manganese exist on land, but are increas- European Space Agency’s Space Solutions initiative for a study ingly dif? cult to extract sustainably. Subsea mining, with the aimed at developing new environmental monitoring technology abundant resources
.com Blue Trail Engineering was founded over a year ago, and in that short time has become a key player in the marine robotics industry. Its Cobalt Series miniature waterproof connectors and cables are designed to offer high reliability at a fraction of the size and cost. In addi- tion, it produces
need for manual valuable investments systems for this purpose. work by divers. The patented au- and increase the avail- Rexroth Blue Trail Engineering: Cobalt Connectors Blue Trail Engineering introduced its new Cobalt Series or 20 amps on 4 pins. Connector shells are keyed and feature a waterproof connectors
Mackinac is a dynamic and complex location within which to make accurate wave measurements,” explained Dr Meadows. Prior Solutions for Wave Measurement Cobalt Series dry-mate connectors ofer the same For decades, the standard approach to wave measurement reliability as larger subsea connectors, but at a
state’s regulations. 25cm thick. The minerals of commercial Although the technical challenges are Some of the Paci? c Island nations interest are cobalt, titanium, platinum daunting for any type of deep-sea min- which early on had signi? cant offshore SOLWARA1 Mining Support Vessel in FUJIAN province
E-ferry tomorrow’s promises.’ Ellen is a proprietary high-energy graphite/NMC (nickel- We started out by asking, “What makes your engines / manganese cobalt lithium oxide) and LTO (titanate lith- propulsion systems the better choice for any brown water ap- ium oxide) cells, according to Dean Jennings, vice
ENVIRONMENTAL REGULATIONS sels (OSVs) will continue to rise as many ships that were Gulf of Mexico, as part of Cobalt International Energy’s mothballed up during the downturn will not return to the bankruptcy auction sale. The deal, which was reported to market. With the number of OSV’s now being
upstream players production unit and 35% are LNG lique- oil, we see the worse being over – and shore ? elds. FPSOs represent 64% of the like Premier, Cobalt, others. ExxonMo- faction or regasi? cation units. bil, for example, in March said it will recovery underway. The world produc- installations,
by visiting: https://www.worldenergyreports.com/ reports/trial Bonga FPSO (Photo: Shell) stream players like Premier, Cobalt, others. ExxonMobil, for example, in March said it will budget $23.2 billion in capital spending in 2016 – down 25% from the $31.1 billion spend- ing
, the materials their production and utilization around rpm, only a 1.7% relative slip causing sumption and eliminates undesired start/ were based on cobalt-tungsten-chromi- the world. a ~1.6% reduction in ef? ciency, it rep- stop engine cycles. um iron alloys. Aluminium-nickel-co- resents a 17% relative
There have been major advances in cylinder coating technologies, including metallic/metal mix systems applied with high velocity oxygen ? ame (HVOF) or cobalt alloy coatings applied via plasma arc welding. In hydraulic actuator design there is always an interaction between seals, ? uid, and material surface
to plot and sample the rich nodule fields between the Hawaiian Islands and Baja California. The nodules contain manganese, nickel, copper, and cobalt, and are so abundant that known ocean deposits could last for centuries. Conrad G. Welling, OMCO vice president- programs, said: "Two types
implication of enormous importance. It opens the door to self-sufficiency for the United States in at least four essential minerals — manganese, cobalt, copper and nickel. The principal speaker at the 88th Annual Banquet of the So- ciety was David S. Lewis Jr., chairman of the board and chief
small industrial applications of laptops, smart phones and small DC power supplies, the Corvus Energy sys- tem utilizes a Lithium Nickel Manga- nese Cobalt (NMC) confi guration. The Lithium NMC battery, beyond supply- ing stronger initial power, also provides a better life cycle, ambient temperature
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methods, economics of mining manganese nodules, and the legal framework for deepsea exploitation. Manganese nodules, containing nickel, cop- per, cobalt and manganes? have become the most economically important sediment of the ocean floor. When the deepsea camera replaced coring and dredging