CHAPTER 9 System Control Electronics The same basic set of electronics hardware is used in both low- and high-voltage systems: main contactor, precharge contactor, high-voltage interlock loop (HVIL), manual service disconnect (MSD), fuses, bus bars, cell interconnect boards, and low- and high-voltage wiring harness. The assembly of these components is often referred to as the high-voltage front end (HVFE). The type of electronics that make up the HVFE and are chosen will depend greatly on the total voltage of the system.
A system with a voltage over 60 V is typically considered high voltage, which means that contact with voltage at or above this level will cause serious injury and potentially death to anyone who comes into contact with it. Therefore HV systems require an additional level of safety precautions, which must be taken in the design in order to ensure human safety while working with or around the system. Systems below 60 V are considered low voltage; someone making contact with its com- ponents may get a shock, not a life-threatening injury. Systems of this type do not require the same amount of safety hardware and controls as are necessary in their HV cousins.
Though it is a good practice to include appropriate safety systems even in an LV battery system. While most automotive applications peak at around 400 V, there are some very-large MWh-size systems used in stationary energy and large industrial applications that can exceed 1000 V. The same concepts apply to these large systems; however, with these high voltages components must be sized appropriate to achieve the maximum voltage rating of the system.
As mentioned in the chapter on battery management systems (BMSs), another important aspect of battery design that must be evaluated during the design is ensuring that the system has proper electromagnetic compatibility (EMC) and electromagnetic interference (EMI) protections. This includes the use of proper shielded wiring where necessary as well as evaluating the design and location of any PCB and control boards in the system. The other item that can assist in managing EMC/EMI issues is the material that is selected for the enclosure. We will discuss this in more detail in Chapter 11 Mechanical Packaging and Material Selection.
But the use of a metal enclosure can greatly help to mitigate the emissions of electromagnetic waves outside of the energy storage system. The Handbook of Lithium-Ion Battery Pack Design. http://dx.doi.org/10.1016/B978-0-12-801456-1.00009-9 Copyright © 2015 Elsevier Inc. All rights reserved. 103