Under the new regulations of the electric bicycle industry, BMS test system equipment can improve measurement accuracy in the following ways:

Optimization and upgrading of sensors

The accuracy and resolution of temperature sensors directly affect BMS's monitoring and control of battery temperature. A temperature sensor with high accuracy and fast response speed should be selected, and its measurement error should be controlled within ±1°C to timely and accurately reflect the temperature change of the battery. For battery cells at different positions in the battery pack, multiple temperature sensors may need to be arranged to fully monitor the temperature distribution of the battery.

The installation position of the temperature sensor also needs to be carefully designed, and it should be ensured that the sensor can be in close contact with the battery to accurately measure the temperature of the battery. At the same time, the installation method of the sensor should be easy to maintain and replace to ensure the long-term stable operation of the sensor.

In order to accurately measure the current changes of electric bicycles under different driving conditions, current sensors with fast response speed and high accuracy should be selected. For example, in the case of instantaneous large current changes such as acceleration, deceleration or climbing of electric bicycles, the sensor can quickly and accurately capture the current changes and accurately transmit them to the BMS test system. For the measurement of small currents, the sensor should also have sufficient sensitivity to detect small current changes such as battery self-discharge.

The range selection of the current sensor is also very important. The sensor with the appropriate range should be selected according to the actual current range of the electric bicycle to avoid measurement errors caused by too large or too small range. At the same time, the sensor should have good anti-interference ability, be able to work stably in the complex electromagnetic environment of the electric bicycle, and not be interfered by the external electromagnetic field.

Choose a high-precision voltage sensor, and its accuracy should at least meet the industry standard requirements. For example, for the common battery voltage range of electric bicycles, the measurement error of the sensor should be controlled within a very small range, preferably to achieve an accuracy level of ±0.1% or even higher. This requires the sensor to have high resolution and good linearity, and to accurately reflect the voltage changes of the battery under different charging and discharging conditions.

Consider using a voltage sensor with temperature compensation function. Because the voltage of the battery will be affected by temperature, there will be certain fluctuations at different operating temperatures. Sensors with temperature compensation function can correct the voltage measurement value according to the temperature information monitored in real time, thereby improving the accuracy of voltage measurement.

2. Improvement of signal conditioning circuit:

Filtering processing: In the BMS test system, the signal conditioning circuit should have a good filtering function to remove noise and interference in the signal. For example, low-pass filters, high-pass filters or band-pass filters are used to filter according to different signal frequency characteristics to improve the signal-to-noise ratio. For high-frequency noise, capacitor filtering, inductor filtering or RC filtering can be used to remove it; for low-frequency noise, digital filtering can be used to process it.

Amplifier circuit: According to the amplitude of the sensor output signal, the amplifier circuit is reasonably designed to amplify the signal to a range suitable for A/D conversion. The amplifier circuit should have high gain, low noise and good linearity to ensure the accuracy of the signal after amplification. At the same time, the stability of the amplifier circuit is also very important, and changes in the amplification factor due to temperature changes, power supply fluctuations and other factors should be avoided.

Signal isolation: In order to prevent signal interference between different circuits, signal isolation technology should be used. For example, optocoupler isolation, transformer isolation or capacitor isolation are used to isolate the input signal from the output signal to improve the signal's anti-interference ability.

3. Improvement of A/D conversion technology:

Improve the resolution of A/D conversion: Select a high-resolution A/D converter to increase the number of bits of the digital signal, thereby improving the measurement accuracy. For example, using 16-bit, 24-bit or even higher-bit A/D converters can convert analog signals into more accurate digital signals and reduce quantization errors.

Optimize the sampling frequency of A/D conversion: According to the working characteristics and measurement requirements of the electric bicycle battery, reasonably select the sampling frequency of A/D conversion. A sampling frequency that is too low will cause signal loss and affect the accuracy of the measurement; a sampling frequency that is too high will increase the burden and cost of the system. Generally speaking, the sampling frequency should be at least twice the highest frequency of the signal to ensure that the signal changes can be accurately collected.

Use differential input A/D conversion: Differential input can effectively suppress common-mode interference and improve the accuracy of A/D conversion. In the BMS test system, differential input A/D converters should be used as much as possible, and the signal output by the sensor should be differentially converted before A/D conversion, thereby improving the accuracy of the measurement.

4. Calibration and verification:

Regular calibration: BMS test system equipment should be calibrated regularly to ensure the accuracy of the measurement. Calibration can use standard batteries, standard signal sources, etc. as references to calibrate sensors, signal conditioning circuits, and A/D conversion circuits. The calibration cycle should be determined according to the frequency of use and accuracy requirements of the equipment. It is generally recommended to calibrate at least once a year.

Verification test: Before the equipment is put into use and during use, a verification test should be performed to verify whether the measurement accuracy of the equipment meets the requirements. The verification test can be tested using an actual electric bicycle battery, and the measurement results of the BMS test system equipment are compared with the measurement results of the standard measuring instrument to analyze whether the measurement error is within the allowable range. If the measurement error is found to be large, the cause should be found and adjusted in time.

5. Software algorithm optimization:

Data filtering algorithm: Use a suitable data filtering algorithm to process the collected signal to remove noise and interference. For example, use algorithms such as mean filtering, median filtering, and Kalman filtering to filter continuous measurement data to improve the accuracy and stability of the data.

Error compensation algorithm: According to the characteristics of the sensor and the measurement environment, an error compensation model is established to compensate the measurement results. For example, for the effect of temperature on voltage and current measurement, a temperature compensation model can be established to correct the measurement results based on the temperature information monitored in real time.

Data fusion algorithm: Combine the data of multiple sensors and use data fusion algorithm to make a comprehensive judgment on the battery status. For example, the data of sensors such as voltage, current, and temperature are fused, and algorithms such as neural networks and fuzzy logic are used to evaluate the remaining power and health status of the battery to improve the accuracy of the evaluation.

With the continuous advancement of battery technology, BMS test equipment will also be continuously upgraded to meet the needs of more efficient, safer and smarter battery management. All test equipment in the KC-BMS test system is independently developed by Kingcable's own instrument brand. The overall architecture is modular, and the communication protocol and communication interface adopt unified standards to facilitate later expansion and maintenance. The KC-BMS test system has high integration and wide application coverage. The system adopts software and hardware integrated design and is rich in functions. While ensuring the stable operation of the system, it can quickly meet more than 90% of the BMS project testing needs of various types in various industries such as power batteries, energy storage systems, and power tools.