SYNCHRO-SYM VIDEO

 

 

- Real Innovation For Our Energy Future -

 

 

 The Concept of Brushless Real Time Control (BRTC):

 

The attractive attributes of the wound-rotor doubly-fed synchronous electric machine system, such as lowest cost, highest torque and power density, and highest efficiency, have motivated experts to study solutions for the associated instability and multiphase-brush-slip-ring issues since at least the 1960's:

 

The problem of inherent instability (hunting) uncontrollable torque angle is an old one … the problem of accelerating the machine and synchronizing it to the power system has continued. [1] [page 526, column 2, paragraph 2]

 

Synchronous electric machines and electric machine systems are subject to oscillatory behavior similar to that associated with a simple spring-mass mechanical system. These oscillations occur because the principle torque produced by the machine is proportional to a position variable. Thus, the motion is approximately characterized by a second order differential equation in which the dominant terms are the inertial torque and the position-dependent (synchronizing) torque. [2] [Page 652 paragraph 1]

 

Another interesting and potentially useful device in which the absence of proper damping torques creates a stability problem is the doubly-fed synchronous machine. The velocity dependent torques produced during hunting in this machine are in a direction to increase the oscillation and render the machine unstable. Unfortunately, the conditions which allow full advantage to be derived from the possibility of delivering energy to both the rotor and stator (reduced frame size for a given output at twice normal synchronous speed) are the same conditions which create unstable operation. Thus the desirable steady-state features of this machine are not available because of the stability problems. [3] [Page 652 paragraph 2]

 

Like the multiphase-brush-slip-ring issue, the solution to the stability issue has been hypothesized for some time:
 

…stabilize the system, …the minimum-time …has been found to be superior." [4] [From Page 799, paragraph 1]

 

 

"Control by Simulation" uses an inexact implementation of the process to be controlled for determining the control response, such as using an offline software algorithm with calculation delays and process anomalies with obvious differences from the actual electric machine process. In contrast, "Control by Emulation" uses an exact implementation of the process to be controlled for determining the control response by exactly duplicating the process to be controlled, such as by an exact but instrumented operating model or prototype of the process without process delays. 

 

Too slow to be real-time solutions, all of today's state-of-art electric machine control methods use derivatives of "control by simulation," such as derivatives of Field Oriented Control or Flux Vector Control that measure and synthesize signals by offline software algorithms with relatively long calculation delays, difficult measurements of slow shallow slope signals, and Kalman Filters estimating rotor time constants. Instead, experts have been waiting for the invention of an instantaneous and automatic "control by emulation" as now only provided by the patented Brushless Real Time Control (BRTC) of Best Electric Machine (BEM).  BRTC is explained in the SYNCHRO-SYM's concept of operation.

 

 


[1] Norbert L. Schmitz and Willis F. Long, “The Cycloconverter driven Doubly-fed Induction Motor,” IEEE Transactions on Power Apparatus And Systems, Vol. PAS-90, No. 2, March/April 1971, pp. 526-531.

[2] D. W. Novotny and N. L. Schmitz, “Parametric Pump-Down of Synchronous Machine Oscillations,” AIEE Great Lakes District Meeting, Fort Wayne, Ind., April 25-27, 1962. Page 652-657.

[3] D. W. Novotny and N. L. Schmitz, “Parametric Pump-Down of Synchronous Machine Oscillations,” AIEE Great Lakes District Meeting, Fort Wayne, Ind., April 25-27, 1962. Page 652-657.

[4] A.H.M.A Rahim, “Stabilizing Controls For A Doubly Fed Synchronous-Induction Machine,” IEEE Transaction on Energy Conversion, Vol. 3, No. 4, December, 1988, pg 799-805


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Note: The Radial Flux prototyping of the Advanced Brushless Wound-Rotor Synchronous Doubly-Fed Electric Motor Or Generator System is shown as our Icon, which predates the axial-flux SS-EMS Technology.

 

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