Recommended: Recommended for BMS isolation transformers

In order to ensure the safety of the battery and prolong the service life, the BMS battery management system came into being. The battery management system (BMS) connects to the high-energy battery pack and manages the charging and discharging of the battery pack, as well as monitoring basic safety factors, including temperature, state of charge, and state of health of the battery pack. Waltiger BMS isolation transformers adopt a high level of automation in the production process to improve product quality and production efficiency.

VOOHU BMS network transformer, with common mode choke for noise suppression, is made of high insulating material, and supports 1000VDC operating voltage and 6400VDC/4242VAC isolation voltage. The wide-temperature resistant magnetic ring design makes it suitable for environments from -40°C to +125°C, and is available in single and dual channels. Advanced circuit isolation and EMI mitigation for safe and efficient operation of e-mobility and industrial battery management systems (BMS). Suitable for most large BMS IC chipsets, it is the best solution for electric vehicles (EVs) and energy storage systems (ESS) with multiple large battery packs in series.

From new energy vehicles, electric bicycles, to energy storage systems, drones, as long as there is a battery, there is a BMS.

VOOHU BMS – Common Isolation Scheme

1.Tolerance

Capacitive isolation (not the same PCB)

9.2.1.2.10.2.1BQ79606A-Q1 drivers and protocols are for drive transformer and capacitive isolation for daisy-chain communication. The following sections detail the implementation of capacitive isolation. Note that both types of isolation are possible in the system and there are no differences in the settings for each device. For example, transformer isolation can be used between low- and high-voltage boundaries to achieve galvanic isolation, while capacitor isolation can be used between modules in a stack. The diagram below shows capacitive isolation with and without chokes. Chokes add extra robustness in BCL noise and long cable applications. With capacitors and chokes, 300mA BCl noise can be easily achieved. For purely capacitive isolation, up to 200mA BCI can be achieved with a 1.7 meter cable.

2.Transformer isolation

While a common-mode choke filter is not required for cable lengths of less than 2m and BCl performance of less than 200mA, longer cable lengths or unusually noisy applications may require the use of a common-mode choke filter. Capacitive isolation plus chokes have better noise immunity than using capacitors alone. For 1.7m cables, BCl noise up to 200mA can be passed using capacitor isolation only, according to the 1S0 11452-4BCl specification, and 300mA BCl noise can be handled if chokes are added. For these applications, use an automotive-grade common-mode filter of at least 100uH to 500 uH for proper operation. For optimal performance in noisy environments, use a dual common-mode filter (470 jH). The recommended impedance of the choke is at least 1K at 1MHz to 100MHz and above 3000 at higher frequencies.

specification

The BQ79606A-Q1 is designed and tested with transformers ranging from 150uH to 650uH. The recommended parameters for isolation transformers are as follows.
Inductance: 150uH to 650uH
Leakage inductance: ~20uH
Car ratings
Operating temperature: -40°C to 125°C Isolation voltage: Depends on total battery pack voltage (e.g. 2500V AC, 1000V DC for 400V system)

3.Opto-coupling isolation

UART Optical Isolation

UART Optical Isolation Daisy Chains can use optical isolation instead of transformer or capacitive isolation, as shown in the figure

4.Digital IC isolation

VOOHU BMS inductive type

The inductive BMS monitors the battery status by detecting the current change when the battery is charged and discharged, and has the characteristics of fast response speed and strong anti-interference ability.

Volhu BMS capacitive type

Let’s talk about BMS capacitive type. Capacitive BMS monitors the battery status with high accuracy by sampling the battery voltage, which is suitable for a variety of battery types and has the advantage of good stability.

VOOHU BMS capacitor + inductor integrated

The transformer is integrated with the management system to achieve energy conversion and signal transmission, which is efficient, compact and safe.

VOOHU’s BMS isolation transformer products are AEC-Q200 compliant, automotive-grade, and have the necessary functions to monitor important safety factors such as temperature, state of charge, and equipment health. Surface-mount technology supports a widely used serial daisy-chain/isoSPI™ communication interface with higher data rates.

Recommended model of VOOHU BMS isolation transformer