Synchronisation of Wheels of Solar Car

My first speed control I made analog, with power transistors and a reference circuit LM.... IC. Worked as a regulated power supply. But that is NOT the way to go because of losses - (heat from transistors) Try to make a pulse width controller and use the power semiconductors in switch mode. Real synchronizing isn't necessary, the driver can easily take care of this.

I work in electric traction.

Traditional DC drive didn't compensate for the differing wheel speeds during turning and worked fine, at least on the monsters I work on where the traction motor armatures are connected in series.

With AC traction more care is taken utilising the capabilities of seperate inverters to provide slip and slide control. The speed of all 4 wheels is monitored and the frequency compensated when required. By monitoring the front wheels the program decides if the machine is turning or slipping and responds.

In a simpler situation some use of the slip can be utilised, but be aware if one motor is driven at above syncronous frequency (the outside wheel) that motor will regenerate and the effect can be quite nasty, the regenerated torque can feel like lock up in very sharp turns. Failure of a wheel speed sensor on the drive wheels has the same effect (complete lock up as the invereter returns to low frequency) unless programmed out which would defeat the slip / slide feature.

In attempting to devise a PWM drive for DC applications care must be taken selecting the topology and I would recommend visiting the Australian Model Engineering website where an excellent series of articles on PWM control of small traction motors has been published in the Magazine. The article explains the issues better than I could in reasonable space here. The articles are a bit long winded as they have a target audience of Steam Enthusiasts.