OK, here we go...
Theory of operation:
When the switch is turned on, R1 feeds voltage to the FET gates, which will be clamped by the zener diode.
Initally, the controller (-) will be at the same voltage as controller (+).
As the FETs turn on, the controller (-) line starts to pull down, causing current flow through the capacitor.
The dV/dt of the controller voltage will be constant to match the zener current. This will cause the current flowing into the capacitors of the controller to be constant during the precharge. Once the controller is fully on, current ceases to flow through C1 and the gate voltage climbs to 12v. Turning the switch off shorts the gate, immediately turning off the FETs and slowly charging C1.
C1 needs to be non-polar and rated for the full pack voltage.
Some approximate math: Lets say the pack voltage is 62V, so the voltage across R1 is 50V. This makes the zener current 50uA. With 1uF for C1, this will allow a dV/dt of 50V/second on the output.
If the controller capacitors total 1,000uF, the current would be a constant 50mA during precharge, for about 1 second.
If the controller capacitors total 10,000uF, the current would be 500mA.
If one wants to use this without a switch and just disconnect the battery, the schematic below should work.
Theory of operation:
When the switch is turned on, R1 feeds voltage to the FET gates, which will be clamped by the zener diode.
Initally, the controller (-) will be at the same voltage as controller (+).
As the FETs turn on, the controller (-) line starts to pull down, causing current flow through the capacitor.
The dV/dt of the controller voltage will be constant to match the zener current. This will cause the current flowing into the capacitors of the controller to be constant during the precharge. Once the controller is fully on, current ceases to flow through C1 and the gate voltage climbs to 12v. Turning the switch off shorts the gate, immediately turning off the FETs and slowly charging C1.
C1 needs to be non-polar and rated for the full pack voltage.
Some approximate math: Lets say the pack voltage is 62V, so the voltage across R1 is 50V. This makes the zener current 50uA. With 1uF for C1, this will allow a dV/dt of 50V/second on the output.
If the controller capacitors total 1,000uF, the current would be a constant 50mA during precharge, for about 1 second.
If the controller capacitors total 10,000uF, the current would be 500mA.
If one wants to use this without a switch and just disconnect the battery, the schematic below should work.