I am aware of many ways a load can be controlled in terms of its current demand, however, does any know how EV charging demand is controlled. If I understood that many EVs have a 3.6KW or 7KW setting but nothing onboard that would adjust current demand. How is close control likely to be effected?
The charger clever bit is in the car, and can modulate the load, rather like a lamp dimmer, by changing the on-to off time ratio of the switching transistors. This is done in response to the duty cycle (pulse width modultion = PWM) of a 1KHz tone generateed by the charging point that you have just plugged it into,
16% PWM is a 10 A maximum, a 25% PWM is a 16 A maximum, a 50% PWM is a 32 A maximum
normally the programmable current is not really just these discrete values , but can be varied continuously (you could make a charge point with a twiddly knob to set the mark to space ratio and then allow you to wind the current load the car presents up and down at will - in reality it is fixed at build time).
As graham alludes some use CAN bus instead, but not yet many
The charger clever bit is in the car, and can modulate the load, rather like a lamp dimmer, by changing the on-to off time ratio of the switching transistors. This is done in response to the duty cycle (pulse width modultion = PWM) of a 1KHz tone generateed by the charging point that you have just plugged it into,
16% PWM is a 10 A maximum, a 25% PWM is a 16 A maximum, a 50% PWM is a 32 A maximum
normally the programmable current is not really just these discrete values , but can be varied continuously (you could make a charge point with a twiddly knob to set the mark to space ratio and then allow you to wind the current load the car presents up and down at will - in reality it is fixed at build time).
As graham alludes some use CAN bus instead, but not yet many
