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CN-122001052-A - Battery life-prolonging charging optimization method based on PWM waveform

CN122001052ACN 122001052 ACN122001052 ACN 122001052ACN-122001052-A

Abstract

The invention discloses a battery life-prolonging charging optimization method based on PWM waveforms, which comprises the following steps of step 1, battery initial state judgment and pre-charging; step 2, PWM up-flow transition phase, step 3, heavy current constant current charging phase, step 4, PWM down-flow transition phase, step 5, light current constant current full charging and cut-off. The method mainly adopts the principle that the electrochemical inertia characteristic of a battery system is utilized, and a perceivable and smoothly-changing average current in the battery is generated through a PWM waveform with alternating high-frequency positive and negative currents, so that the problems of impact and polarization caused by the traditional step current are effectively avoided while quick charge is realized. The invention realizes seamless transition of charging current among different stages by accurately controlling the change rule of the duty ratio of PWM, and provides an effective scheme for improving the charge acceptance of the battery, the cycle life and the safety.

Inventors

  • WANG JIAJUN
  • LIU JIAXUAN
  • ZHANG YUANXI
  • WANG BAOZHENG
  • LI RUOSONG
  • LIU QINGSONG
  • An Hanwen

Assignees

  • 哈尔滨工业大学

Dates

Publication Date
20260508
Application Date
20260128

Claims (9)

  1. 1. A battery life-prolonging charge optimization method based on PWM waveforms, characterized in that the method comprises the steps of: Step 1, judging and pre-charging the initial state of the battery: step 1-1, taking a commercial lithium ion battery to be charged, and testing the current voltage value; step 1-2, when the voltage of the battery is lower than 3.0V, judging that the battery is in a deep discharge state and needs to enter a pre-charge process, wherein for the battery with the voltage higher than 3.0V, the battery can directly enter a PWM (pulse width modulation) current rising transition stage; Step 2, PWM up-flow transition stage: step 2-1, connecting the battery with the pre-charge or qualified voltage in the step 1 with a bidirectional programmable charge-discharge instrument and a temperature sensor, and fixing the battery on a battery charge-discharge test mould; Step 2-2, setting the temperature of the incubator to be a fixed value between 20 and 30 ℃, and transferring the battery and the die thereof in the step 2-1 into the incubator body after the temperature of the incubator body is stable, and sealing the incubator body; Step 2-3, recording battery voltage at the beginning of a transition stage, setting a PWM current-rising step, wherein a reference positive current is set to be 0.5-1.5C, a reference negative current is set to be 0.0-0.2C, a PWM period is set to be 1-50 s, the duty ratio is increased from 0% to 100%, the transition time is 1-5 min, and smooth rising of current from an initial value to a target large current value is completed; step 3, a large-current constant-current charging stage: After the PWM current rising stage is completed, according to the basic positive current of 0.5-1.5C after current rising, the cutoff voltage is selected to be 4.0-4.1V, and the high-current constant-current charging is carried out until the cutoff voltage is reached; step4, PWM down-flow transition stage: step 4-1, after the high-current constant-current charge is carried out until the battery voltage reaches 4.0-4.1V, placing 10 s, and transferring to a PWM (pulse width modulation) current reduction step; Step 4-2, setting a PWM current reduction step, wherein a reference positive current is set to be 0.5-1C, a reference negative current is set to be-0.5C, a PWM period is set to be 1-50 s, the duty ratio is linearly reduced from 100% to 0%, the transition time is 1-5 min, and the smooth reduction of the current from a large current value to a target small current value is completed; step 5, small-current constant-current full charge and cut-off: Step 5-1, after the PWM current reduction transition is completed, switching to a low-current constant-current charging step, setting the charging current to be 0.1-0.3C according to the cut-off current when the duty ratio is 100% after PWM current reduction, continuously monitoring the battery voltage, and immediately stopping charging when the battery voltage reaches 4.2V; and 5-2, keeping the temperature sensor in the step 2-1 synchronously started in the whole process, and outputting a temperature detection result for monitoring the thermal behavior in the charging process.
  2. 2. The method for optimizing battery life-prolonging charge based on PWM waveform according to claim 1, wherein in step 1-1, the commercial lithium ion battery to be charged is one of cylindrical battery 18650, 21700, 4680, soft pack battery, prismatic battery, and button cell battery.
  3. 3. The method for optimizing battery life-prolonging charge based on PWM waveform according to claim 1, wherein in the step 1-1, the battery system is one of a nickel-cobalt-manganese ternary lithium ion battery, a lithium cobaltate battery and a lithium metal battery.
  4. 4. The method for optimizing battery life-prolonging charge based on PWM waveform according to claim 1, wherein in step 1-2, for the battery to be pre-charged, the current voltage value is read, a constant current charging step is set, and the charging current is 0.1-0.5C until the battery voltage rises to 3.0V.
  5. 5. The method for optimizing battery life-prolonging charge based on PWM waveform according to claim 1, wherein in step 2-1, the bidirectional programmable charge/discharge instrument is one of a high-precision linear power supply and a high-frequency switching power supply.
  6. 6. The method for optimizing battery life-prolonging charge based on PWM waveform according to claim 1, wherein in step 2-1, the temperature sensor connection is one of an external fitting connection and an internal implantation connection.
  7. 7. The battery life-prolonging charge optimizing method based on the PWM waveform according to claim 1, wherein in the step 3-1, the PWM waveform is one of square wave, triangular wave and sine wave with alternating positive and negative currents.
  8. 8. The battery life-prolonging charge optimizing method based on the PWM waveform according to claim 1, wherein in the step 3-1, the duty cycle variation rule of the PWM is one of linear variation, nonlinear variation and S-shaped curve variation.
  9. 9. The method for optimizing battery life-prolonging charge based on PWM waveform according to claim 1, wherein in step 5-2, the temperature detection result is used for one or more of battery thermal model construction, charging strategy real-time feedback regulation, and charging safety pre-warning.

Description

Battery life-prolonging charging optimization method based on PWM waveform Technical Field The invention belongs to the technical field of battery performance optimization, relates to a battery charging protocol optimization method, and in particular relates to a battery life-prolonging charging optimization method based on PWM waveforms. Background The lithium ion battery has the characteristics of long endurance, high specific energy, high power and the like, and is widely applied to the fields of electric traffic, 3C digital codes and the like. Lithium ion batteries generally face the need for rapid charging, and conventional solutions are to increase charging current, achieve high-rate charging, or employ pulsed charging. However, sudden increases or drastic changes in current may cause cracking of electrode materials, electrolyte decomposition, etc., resulting in rapid degradation of the cycle life of the battery. The prior art considers that from the charging process, the severe current change is avoided by regulating and controlling the charging and discharging protocol process steps, but the battery failure problem caused by current impact cannot be avoided by the method. In addition, the method for improving the quick charge performance by regulating and controlling the charge and discharge strategy is easily influenced by a battery system, electrode materials and the like, and has poor universality. Therefore, development of a new rapid charging protocol for lithium ion batteries is needed to extend the service life of the batteries under the rapid charging conditions. Disclosure of Invention The invention aims to provide a battery life-prolonging charging optimization method based on PWM waveforms, which is used for relieving the influence of current impact on the service life of a battery. Based on the continuity characteristic of PWM waveform and the inertia characteristic of a battery system, the method can remarkably improve negative effects such as battery active material fragmentation caused by current surge by applying PWM waveform current at the initial stage and the final stage of charging to relieve the current surge/drop problem. The invention is a general regulating strategy, and is suitable for multiple types and multiple kinds of lithium ion batteries. The invention aims at realizing the following technical scheme: A battery life-prolonging charging optimization method based on PWM waveform comprises the following steps: Step 1, judging and pre-charging the initial state of the battery: step 1-1, taking a commercial lithium ion battery to be charged, and testing the current voltage value; Step 1-2, when the voltage of the battery is lower than 3.0V, judging that the battery is in a deep discharge state and needs to enter a pre-charging process, and for the battery with the voltage higher than 3.0V, directly entering a PWM current-rising transition stage; Step 2, PWM up-flow transition stage: step 2-1, connecting the battery with the pre-charge or qualified voltage in the step 1 with a bidirectional programmable charge-discharge instrument and a temperature sensor, and fixing the battery on a battery charge-discharge test mould; Step 2-2, setting the temperature of the incubator to be a fixed value between 20 and 30 ℃, and transferring the battery and the die thereof in the step 2-1 into the incubator body after the temperature of the incubator body is stable, and sealing the incubator body; Step 2-3, recording battery voltage at the beginning of a transition stage, setting a PWM current-rising step, wherein a reference positive current is set to be 0.5-1.5C, a reference negative current is set to be 0.0-0.2C, a PWM period is set to be 1-50 s, the duty ratio is increased from 0% to 100%, the transition time is 1-5 min, and smooth rising of current from an initial value to a target large current value is completed; step 3, a large-current constant-current charging stage: After the PWM current rising stage is completed, according to the basic positive current of 0.5-1.5C after current rising, the cutoff voltage is selected to be 4.0-4.1V, and the high-current constant-current charging is carried out until the cutoff voltage is reached; step4, PWM down-flow transition stage: step 4-1, after the high-current constant-current charge is carried out until the battery voltage reaches 4.0-4.1V, placing 10 s, and transferring to a PWM (pulse width modulation) current reduction step; Step 4-2, setting a PWM current reduction step, wherein a reference positive current is set to be 0.5-1C, a reference negative current is set to be-0.5C, a PWM period is set to be 1-50 s, the duty ratio is linearly reduced from 100% to 0%, the transition time is 1-5 min, and the smooth reduction of the current from a large current value to a target small current value is completed; step 5, small-current constant-current full charge and cut-off: Step 5-1, after the PWM current reduction transition is completed, swit