Electric Blue auto convertions wrote:
When I was working for Clark fork Lifts in the late 60s they didn't have controllers as we have today, They used a set of Caps, High voltage rectifiers and Xfrmers...
If these controllers made a noticeable whistle, those rectifiers were SCRs (Silicon Controlled Rectifiers). They were the first truly high power semiconductors. The controllers worked very much like our modern ones, but switching speeds were lower, so you heard an audible whistle. Their efficiency was reasonably good, and they could be very reliable. It's not hard to find old SCR controllers, still working today.
there was 4 large contactors, one was reversing, one was for field weakening. They had what was a very rudimentary "controller" only about 5 or 6 resistors a few diodes and some small caps, this went to the "gas peddle". The large Recs could handle over 1,000 amps.
The controllers looked simple compared to our modern ultracomplex sensibilities. However, they often had a full set of features that our modern controllers tend to leave out (field weakening, reverse, regen, etc.).
The earliest electric fork lift I worked on was from the early 40s, It had a "gear shift" lever that hit 3 different resistors, "large" for different speeds, and one reversing contactor, simple and it was still in use way back when I had to rebuild the motor.
Resistor control was "old school" even in 1940! Controlling speed with series resistors was the very first method invented, way back in the late 1800s! It didn't take long to figure out that it was cheap and easy, but inefficient.
By the 1900's, EV motor controllers mainly used switches or contactors to rewire the batteries and motors for series/parallel operation. Efficient, but speed control was "jumpy".
By the 1930's, they were using field control, so a small rheostat could regulate a much higher power motor.
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