On Sunday, September 2, 2018 at 4:19:12 PM UTC-6, Bob Youngblood wrote:
On Sunday, September 2, 2018 at 8:43:29 AM UTC-4, gotovkotzepkoi wrote:
Germans have had an electric winch for a long time. Nothing now. Don't
hold your breath for one built in the US. Won't happen. Charge with an
internal combustion engine? What's the point? Why not just use a piston
engine for the winch then?




--
gotovkotzepkoi


I can tell you that the current starting load for a 430 hp electric motor is substantial. Don't know if they are using a soft start or something equal it takes a lot of power to start a 430 hp electric motor. The amp requirements are huge, interesting concept, huge electric requirements. Bob
-------------------

Bob, you are confused by old-school, garden variety synchronous AC induction motors which do require a lights dimming surge of power to get them up to synchronization with a fixed power line frequency. They're inefficient so they're largely been replaced by better technology. The tech is changing so fast it's hard to keep up.

The variable frequency motor (PMSM) used in the winch does not require such a surge to start. RPM is a function of frequency and torque is a function of current. The current it draws is proportional to the torque output required.

Variable frequency AC is provided by a "traction inverter" or VFD which very efficiently converts battery DC to 0 to ~1,000 Hz 3-phase AC. The motor starts gently at 0 Hz and smoothly revs up as the frequency is increased.

The battery is kept charged by a relative small power source which need only supply the average power demand over many launches. As designed, the winch will have far more than needed from a PTO driven generator but almost any source of electricity would do - even a 2,000 Sq Ft solar cell array would work handily.

Battery cost is already so low there is a minimal impact on the cost of the winch. We have quotes for a bigger than needed battery for less than $2,000 and prices are dropping very fast.