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1000V - Battery Management System (BMS) - Gen 1

This document describes the interface, installation, and usage requirements for the Prohelion Battery Management System (BMS).

The BMS provides an easy way to monitor and control an Electric Vehicle battery pack, and can work seamlessly with Prohelion's WaveSculptor motor controllers. It is a mature design with five previous product generations of real-world experience with various types of cells, form factors, and vehicles.

Prohelion Battery Management Unit

Prohelion Battery Management Unit

The BMS consists of two components: multiple Cell Management Units (CMU), which measure and control the individual cells in the battery pack; and a single Battery Management Unit (BMU) which interfaces between the CMUs and the vehicle, controls precharge and other safety systems, and provides total pack telemetry.

Prohelion Cell Management Unit

Prohelion Cell Management Unit

Battery Management System (BMS) Functions

The function of the BMS is threefold, in order of priority:

  • Monitor cell voltages and temperatures, and act on this information to protect the pack against being operated outside acceptable limits
  • Manage the cells, to keep them at equal State Of Charge
  • Report telemetry to the other systems in the vehicle, to allow a graceful reduction in vehicle performance as the battery approaches its limits

The BMS performs these functions by measuring the following parameters:

  • Individual cell voltages
  • Group cell temperatures
  • CMU temperatures
  • Total pack voltage
  • Total DC bus voltage
  • Total pack current
  • 12V supply voltages and currents
  • Contactor status
  • Fan / Pump speeds

To achieve management over the cells and pack, it controls:

  • Individual cell bypass (shunt) balance resistors
  • Pack contactors, including precharging HV loads
  • Battery pack fan / pump
  • Battery charger charging current setpoint

Individual cell voltages are the most critical measurement taken by the system, and in the Prohelion BMS are measured using two separate, redundant circuits, each with it's own analog circuitry, A/D converter, and reference.

All measurements are cross-checked, and any fault in the system can be identified and reported. This system not only gives reliable and accurate cell voltage measurements, it gives trusted measurements.

The Prohelion BMS reports if any measurements are not trustworthy, and this information can be acted on by a higher-level system in the vehicle, for instance by notifying the driver that the vehicle requires servicing.


Cell: A single physical unit, or permanently connected parallel group of units. A parallel group functions electrically as a larger capacity single unit

Battery: A series-connected group of cells

Acronyms and Abbreviations

Acronym Abbreviation
A Ampere
Ah Ampere Hour
BMS Battery Management System
CAN-Bus Controller Area Network - Bus
DC Direct Current
ESS Energy Storage System
HV High Voltage
LV Low Voltage
SoC State of Charge
V Voltage