In the wake of rapid development of electric vehicles, automobile makers tend to spare no effort in the development this product. The prevalent use of electric vehicle is indeed a revolution of vehicles for human beings of this century. In the competition between electric vehicle and traditional motor vehicles, and for the gradual replacement of diesel engine cars, battery-related technology will be critical. Battery allows for high performance efficiency, endurance for longer driving distance, compression of the time for recharging, longer life span of battery, and reduction of the cost of battery production are essential factors for electric vehicles for replacement of traditional diesel engine vehicles. Accordingly, battery management system (BMS) will be one of the critical technologies for such purpose.
BMS is a critical factor for electric vehicles
BMS performs the functions of battery voltage measurement to prevent or avoid excessive power release, excessive charging, overheating, and other abnormal situations. New functions for BMS were developed in line with the development of related technologies. The MC33771 battery cell controller and MC33664 transformer physical layer solution of NXP Semiconductors is an application for lithium ion battery cell control for providing stability, safety and BOM (bill of material) at optimized low cost. In the market of electric vehicle, it can support high-voltage BMS at 800V and BMS at 48V. In addition, it also supports the energy storage systems (ESS), uninterrupted power supply (UPS) in industrial use, electric bicycles and electric cars.
The MC33771 battery cell controller and MC33664 transformer physical layer solution of NXP Semiconductors is a piece of highly integrated battery cell control device for electric cars and critical applications in industry. The topology of the battery is highly flexible and can support a 48V cell matching with an analog front end (AFE). The high speed and stable daisy chain topology provides a smarter substitute solution than the CAN. It just takes 2.6ms to acquire the conversion data from 96 battery cells of the controller to complete fast data acquisition and communications with the system. Furthermore, it can also determine the impedances of individual cells at one time and finish the measurement of voltage and current simultaneously within 65μs.
In performing the functions of inspection and testing, both the MC33664 and MC33771 support the ISO 26262 SafeAssure functional safety standard, and can execute functional verification in high precision including power capacity measurement, current measurement, power cell terminal openings or leaking, and analog to digital conversion.
This solution incorporates the SMARTMOS technology and is an innovative result of NXP Semiconductors after 3 decades of endeavor, which could combine digital, power supply and standard analog functions, and is the chip for analogy and power supply management for cars, consumer electronics, industrial and the network markets. The analog solution uses signal from the real world to control and drive the port of the entire embedded system.
The MC33664 and MC33771 of NXP Semiconductors integrate the current channel and coulomb counting for checking the state of health of the battery and can help to reduce BOM (bill of material) for the application of 48V battery cell and just needs one AFE (analog front end) to synchronize the current channel with measurement of the battery voltage to determine the impedances of individual cells at one time. This will enhance the expected accuracy of the SoC/SoH (state of charge/state of health) of the battery.
Through the selective high-speed differential or SPI communication mode, the solution can process the topology of existing BMS (centralized, distributed daisy chain, distributed CAN) to support high-speed (2Mbps) isolated high-speed differential communication. The cost of BOM could be reduced by transferring CAN to daisy chain without compromising the communication speed. It can quickly acquire data from the battery cell controller for communication and can synchronize the measurement of voltage and current of the cell within 65μs through the one-time determination of impedances of individual cells. It can also handle hot plugging and random cell connection in high stability. Customers will not cause damage to the battery and other devices inadvertently in the course of battery/electronic devices assembly.
This solution can handle ESD/EMC in high stability with ESD (electrostatic discharge) protection and EMC (electromagnetic compatibility) without relying on external component. Through a single package solution, it supports the ISO 26262 SafeAssure standard and features functional verification and diagnosis. With the use of low-level drivers, it helps to simplify software development and reduce the switching cost.
Arrow ESC is located at the Arrow Open Lab (http://www.arrowopenlab.com/) of Hong Kong Science Park with the exhibition of the MC33771 and MC33664 (BATT-14AAAPACK, KRDM-KL25Z, MIT33771TPLEVB and KIT33664EVB) BMS evaluation kit of NXP Semiconductors (http://www.arrowopenlab.com/HkOpenLab/Demo_and_EV_board.html).
You are welcome to visit the exhibition if you have an interest in BMS technology.
The rapid development of electric vehicles brought about keen competition in the market. The very concern of the consumers is the endurance of driving distance and maximum speed of the vehicle after single charging, and the time required for full charging of the cell. These factors are closely associated with the battery management system. If the electric car makers could use a quality BMS, they would outcompete their competitors through differentiation and significantly bolster their competitive position with their products.