Thursday, January 29, 2015

You Gotta Know Where It's Headed!


An email was received a few days ago that confirmed there is a bit more work to do on the presently used electric drive motor controllers. The email was from the last of four potential electric motor controller manufactures that said, in brief, the new controller unit’s  design would cost $20,000 just for the first two prototypes and their engineering would not start for over 6 months, not including another half year to complete the test delivery units.

The current Navitas motor controllers are more sophisticated than needed for our boat powering use. We just use forward, reverse, stop & throttle (FRST). Navitas is a superb control unit but in some instances prohibit too quick a shift in motor direction by temporarily shutting off power. Although this forward to reverse protection is fine in a car, it is downright dangerous in a boat. Reverse is your brakes and if there is a significant pause, then the stopping of the boat is imperiled. A set of criteria must be placed into the controller’s parameter set to counter the tendency to shut down in what is usually some automotive safety mode. For a boat, such a safety mode is not desirable. There is a facility for an outside computer to make changes in the controller’s operation.

The altering of the errant mode is made difficult because of the seemingly limitless parameters that can be set in the controller’s computer. Each of the possible combinations need to be tried. Not knowing how some of the parameters effect others, adds to the mystery. Working the issue with a car is fairly predictable because the wheels are planted on a firm surface with a known physical resistance. Employed on a boat in the slippery water, the same controller lacks a firm set of well grounded tire resistance. Add to the equation wave action, water flow, wind resistance, propeller slip and a host of fluid variables, the task of sorting out a simple land travel problem is made quite difficult in the water.

So for now it is back to a computer being hooked up to the controllers, running through reams of possibilities until some type of trend occurs that can be consistently altered towards fixing the problem. Other electric boats have less sophisticated motors that do not require the Navitas controller. However, those other motors are not as efficient and robust either, which compromises a ship’s seaworthiness. Once programmed to take into account the crucial variables, the dependable controllers and dependable motors will be far superior to their less sophisticated, heavier and shorter life expectancy brethren.

Computer attached to the starboard motor controller to modify the way the controller responses to commands.
Many variables for the system. There are 8 other pages of data that may be changed.
A mass of variables for the throttle.



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