Master BMS circuitry for E-car or Hybrid electrical vehicle

Item

Comments

RS-485 Communication

RS-485 Communications is used to communicate with the battery modules. 

CAN interface

CAN interface will be used to communicate with the host or the charger

Charge Disconnect

When the battery modules are fully charged, they will communicate with the BMU and the BMU has the ability to turn off the charger or open the charger main contactor, interrupting current flow.

Analog/Digital Communications

In case the host controller doesn’t have a CAN interface, the BMU communicates with the host via analog/digital signals. These signals include:

Outputs – SOC (A), disable regen(D), early warning(D), BMU fault(D)

Inputs- 12V ignition (D), vehicle fault (D)

Discharge Interrupt

When the batteries are discharged to the under-voltage protection point, BMU will attempt to alert the host to inhibit discharge. If discharge continues beyond this warning, the BMU will request that the main contactor open or can open it itself.

Insulation measurement

The BMU will check to make sure the battery module is sufficiently isolated from the chassis before and after the main contactor is closed.

Pre-charge circuit

To limit the inrush current into the systems capacitors, a pre-charge resistor is connected to B+ before the main contactor is closed.  This also prevents arcing and pitting across the contact tips.  The BMU will close an auxiliary contactor to place a resistor in line with B+.  After 2 seconds, the main line contactor will close.

Inter-module Balancing

Compensates slight capacity imbalance between different batteries when charging.

Intra-module Balancing

Compensates slight capacity imbalance between different cell-blocks  within one module while charging.

Size

188 mm x 160 mm x 38 mm (7.4 in x 6.3 in x 1.5 in)

Weight

about 550g(1.21lbs)