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The LED of Motors

There are many different types of electric motors. Turntide’s Smart Motor System is based on a Switched Reluctance (SR) design. The particular motor design developed by Dr. Piyush Desai and commercialized by Turntide is referred to as a High Rotor Pole Switched Reluctance Motor (HRSRM).

SRM Background

An SR motor is a type of stepper motor. Stepper motors are unique in that their rotor goes through a sequence of minuscule movements while rotating, rather than rotating in one smooth motion. Think of this the way the second hand on some clocks ticks through a cycle, while on other clocks the second hand rotates continuously. The Turntide Motor System is composed of an SR motor and a controller. The controller houses the power electronics and micro-controller that drive the motor.

 

While SR motors were invented in the 1800s, their use has historically been limited to industrial applications due to cost and complexity. Thanks to the Flourishing of solar, wind and electric vehicle technologies in the last decade, the cost of the power electronics and micro-controllers required to control an SR motor have dramatically decreased. This phenomenon has enabled SMC to promote SR motors for use in commercial applications.

Smart Motor System and HRSRM Background

Turntides's HRSRM design differs from traditional SR motors in one very significant way: as the name suggests, it has more rotor poles than stator poles. The formula is (r = 2*s-2), where r is the number of rotor poles and s is the number of stator poles.


The HRSRM configuration turns out to have very compelling advantages by decreasing the amount that the rotor has to turn before aligning with a set of stator poles. This design makes the motor more controllable, increases motor efficiency, and decreases torque ripple.  Turntide's switch reluctance motor is of this variety.  The motor is the central element of the Smart Motor System.

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Turntide motors do not induce any current onto the rotor like induction motors do.  HRSRM passes a current through the copper winding that wrap the three pairs of bobbins.  As each pair of bobbin is energized a magnetic field is created.  The rotor spokes, which are make from solid ferrous metal, tries to align with the bobbins.  Just as the spokes of the rotor align with one pair of bobbins, the Turntide controller turns off the energy to that phase and then energizes the next pair of bobbins creating a new magnetic field.  This process of energizing the pairs of bobbins on and off happens 20,000 times per second.  The rotor in effect chases the magnetic fields created by the switching of the energy between the phases.  

 

Because the winding are completely enclosed in epoxy and separated between phases and given the fact that no energy is induced onto the rotor, the common modes of motor failure associated with conventional induction motors is eliminated.  Turntide's motors do not have bearing failures or shots between phases.      

When we alter the speed of these motors, rather than changing the frequency as in a VFD connected to an induction motor, we are changing the speed at which we switch energy between phases.  This method of controlling speed allows the Turntide motor to maintain near constant peak efficiency and torque regardless of the speed of the motor.

The Motor Controller

The controller serves two purposes. First, it is the brains for the motor and controls the delivery of power to the motor to make it turn efficiently at the required speed and in the required direction.  Second, it has advanced logic capabilities that allow it to connect to various sensors and actuators to perform as a higher-level system controller.  

The Supervisor 

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The supervisor is the networking and controls interface for the system. It has a number of digital and analog input/output options that allow it to connect to various sensors and actuators and serve as a high-level system controller. It also has communications capabilities that allow it to communicate with other devices through common protocols such as BACNet, or to communicate through the internet with the Turntide's cloud platform.  For Turntide to have remote "sight" and remote programming capabilities into an installed motor system, a Supervisor is required.  Supervisors can connect up to 9 hardwired motors at a single site or up to 27 motors if also connecting wireless.  If a facility wishes to install "blind" motors and no local BMS tie in is required  than a Supervisor is an optional addition to the system.  The motor and controller can operate as programmed without the need for a supervisor.  Turntide's Virtual Facility Management and Remote Mote Monitoring Service is another example of when a Supervisor would be required on a project. 

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