K-Series Brushless DC Motors

Hydrospace K-series BDC motors provide the highest level of power in a small package. These provide a maximum of usable power through the high continuous torque design and high rated speed. All K-series motors use advanced Neodymium-IronBoron permanent magnets and by using advanced, 3-D finite element analysis (FEA) software, Hydrospace optimizes the magnets, windings, geometry and thermal management for ultimate efficiency. All K-series motors are designed to be fully submerged, are oil-filled and pressure compensated. This provides optimal thermal cooling and efficiency over a broad range of operation.


High performance servo control involves dynamic accuracy, velocity regulation and fast settling time. The Kseries motors offer low electrical time constant which allows quick reaction to rapid command changes demanded by high-performance servo drives. A fast mechanical response is possible through a high peak torque to low rotor inertia ratio where less torque is used to accelerate the rotor, and more torque is available for accelerating the load.

Rugged and Reliable

Brushless servo motors are the defacto choice for reliable operation because: 1) they do not have brushes to wear out or burn up at high power output, 2) the motor windings are located right against the motor housing that is continuously cooled, and 3) they have very few moving parts, the bearings. To increase the reliability further, Hydrospace uses oversized bearings to decrease wear and to avoid premature failure. The motors are generally designed to operate in a moderate speed regime between 1500 and 3000 RPM to minimize wear. The bearings are always permanently lubricated by an oil-filled housing. Additionally, the neodymium permanent magnets are conformally coated and highly resistant to corrosion which can cause brittleness in rare-earth magnets. Motors typically have an all-aluminum housing that is compression fit to the stator which maximizes conductive heat transfer to the outside —the main source of heat sinking. Hydrospace motors are available in Stainless Steel or Titanium as applications dictate.


The K-series high power density allows Hydrospace to design a motor that will fit in precious space restrictions often encountered in deep sea systems. The motors can be designed as smaller diameter with a longer length geometry or a shorter length with a larger diameter. All Hydrospace motors have a very high motor constant (Km) which provides the maximum power per unit volume. All motors provide position feedback through magnetic encoders and/or resolvers, which are contactless, inductive devices and again minimize moving parts. Motors can also be designed with Hall Effect sensors and in some cases can be sensorless as well – depending on the type of electronic controller used.


Electrical connectors are always a major consideration in the interface with customer systems. This is a common customization and Hydrospace can adapt the connector geometry, placement and vendor according to customer specifications. Because of the long experience with subsea connectors, Hydrospace extensively tests 100% of all connectors according to a comprehensive in-house test regime to ensure each part meets its specifications to secure longest life and reliability.

Retrofit Designs

The K-series Motor series provides a standard family of designs to choose from. In cases where older motors need to be replaced, Hydrospace is uniquely qualified to adapt one of its standard motors and produce the necessary customization to meet the exact (or better) performance requirements with the same exact physical interface dimensions. Such customization is always difficult for larger motor fabricators. At Hydrospace, this is a regular part of the design and fabrication process and can be easily accommodated, without exorbitant engineering costs. Clients also get to talk directly with design engineers to discuss, brainstorm and plan the issues that are most important to support a new design, a new proposal or to adapt to an existing design.

HGi K5048 15HP 600V Motor

HGi K5048-15HP-600V Motor

HGi K6548 30HP 350V Motor

HGi K6548-30HP-350V Motor

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