Application of TI's high-performance charging and discharging solution in battery test equipment (Battery Test System)

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Application of TI's high-performance charging and discharging solution in battery test equipment (Battery Test System) [Copy link]

 

Battery testing equipment is essential equipment and infrastructure for the battery manufacturing industry. As the demand for lithium batteries in applications such as electric vehicles and portable consumer electronics continues to increase, the demand for lithium battery testing equipment is also on the rise.

Battery testing equipment is used to verify the functionality and performance of batteries before shipping to customers. After assembling a battery cell or battery pack, each cell must undergo at least one fully controlled charge or discharge cycle to initialize the device and convert it into a properly functioning power storage device. The main function of battery testing equipment is to test battery capacity, efficiency, rate, high temperature performance, low temperature performance, storage performance, internal resistance and other indicators. The three most important indicators for the system design of battery testing equipment are charge and discharge accuracy, cost and conversion efficiency.

For the core function of battery testing equipment, battery charging and discharging, there are two popular solutions on the market: digital solutions implemented using DSP and analog solutions built using discrete devices. Both DSP solutions and discrete solutions have their own shortcomings. The software development of DSP solutions is difficult, and the hardware development of discrete solutions is difficult, resulting in a relatively long design cycle for both solutions and a relatively high overall development cost.

In order to help battery testing equipment manufacturers shorten their R&D time and quickly bring their products to market, TI recently launched two sets of high-performance, highly integrated, low-cost battery charging and discharging solutions, targeting medium and high power (10A~200A) applications and low power (3A~6A) applications respectively.

First, for medium and high power applications, TI's reference design is the TIDA-01041x series. The TIDA-01041x series provides three solutions for different current requirements, namely TIDA-01040 (0~50A), TIDA-01041 (0~100A), and TIDA-01042 (0~200A). All solutions guarantee a full-scale charge and discharge current accuracy of <=0.02% and a charge and discharge voltage accuracy of <=0.01%.

As shown in the figure below, the entire TIDA-01041x system is mainly composed of four parts: the core device LM5170 (blue area) is responsible for the power buck-boost part, and its main functions include multi-phase processing, direction switching, peak current control, and current backflow prevention; the INA188 instrument amplifier is responsible for high-side constant current detection; the LM6142 is responsible for voltage amplification detection; the ADS131A04 (24-bit high-precision ADC) and DAC80004 (16-bit high-precision DAC) are responsible for real-time reading and real-time setting of current and voltage, and information can be read and operated through the upper computer graphical interface provided by TI.

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LM5170 is TI's star product and the core of the entire system. The LM5170 integrates dual 5A MOSFET half-bridge drivers that can provide up to 100A of continuous output current. At the same time, a single LM5170 can support two-phase staggered control, which can effectively reduce the inductance, capacitance and input and output voltage ripple. For applications requiring more than 100A, the LM5170 supports multiple chips in staggered parallel connection to provide greater current capability. The following figure shows several solutions for multiple chips in staggered parallel connection.

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In addition, compared with the DSP solution, the LM5170 has a much faster response speed and settling time because it supports both peak current detection and average current detection. The waveform below is based on the -100A to +100A current jump test of the TIDA-01041 (100A) evaluation board (the waveform is -25A to +25A in one phase, and the total current of the four phases is -100A to +100A). The blue signal is the direction control DIR pin, the red is the given current reference signal ISETA of the LM5170, the yellow is the output voltage Vout, and the green is the Iout current. From the figure below, we can see that the response time of the LM5170 under the -100A to +100A current jump condition is only 400s, which is much lower than the response time of the DSP solution under the same test conditions (usually higher than 5ms).

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TI has launched the high-precision and low-cost solution PMP15043 for low-power (<=6A) battery detection applications. The solution mainly consists of three parts: TPS61178 boost DC/DC is responsible for the discharge part, TPS54821 buck DC/DC is responsible for the charging part, current detection is achieved by INA188 instrumentation amplifier, and voltage detection can be achieved by low-cost op amp TLV07 .

At present, most of the low-power (<=6A) battery charging and discharging solutions on the market are built with discrete components. However, as the market's requirements for product accuracy and reliability are getting higher and higher, discrete solutions are increasingly unable to meet market demand. TI has launched the high-precision, low-cost solution PMP15043 for low-power battery testing equipment, which solves these problems very well.

As shown in the figure below, the PMP15043 solution consists of several main parts: TPS61178 boost DC/DC is responsible for the discharge part, TPS54821 buck DC/DC is responsible for the charging part, current detection is implemented by INA188 instrumentation amplifier, and voltage detection can be implemented by low-cost op amp TLV07 . Among them, TPS61178 and TPS54821 integrate power MOSFET and drive circuit, which greatly simplifies the design of the power part and can effectively reduce the debugging time of customers on discrete solutions. TPS61178 and TPS54821 are both very common Boost and Buck chips on the market, and the overall solution is also quite competitive in terms of cost.

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PMP15043 not only has competitive BOM cost, but also excellent performance. The figure below shows the charge and discharge current accuracy curve of PMP15043. It can be seen that the accuracy can be guaranteed within 0.02% in the full current range, which is very suitable for battery detection applications that have very strict requirements on cost and performance.

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In summary, whether for medium or high power application scenarios (>=10A) or for low power application scenarios (<6A), TI can provide the most cost-effective solution. You can view detailed design documents and test reports through the link below.