This charging method not only follows the battery inherent charging acceptance rate, but also can improve the battery charging acceptance rate of electric vehicles, thereby breaking the limit of the battery index charging acceptance curve, which is the new development of the battery charging theory.
Charging stations for electric vehicles
This technology is a patent technology in the United States, it is mainly facing the charging object is nickel-cadmium battery. Because it adopts a new charging method, it solves the memory effect of nickel-cadmium battery, so it greatly reduces the fast charging time of the battery. The charging method of lead-acid battery and the detection method of the charging state are very different from the nickel-cadmium battery, but they can borrow REFLEXTM charging method of a working cycle including forward charging pulse, reverse instantaneous discharge pulse, stop charging to maintain three stages.
Which is based on constant current charging and pulse charging, as shown in FIG. 7. It is characterized by changing constant current charging section to limited-voltage variable current intermittent charging section. In the early stage of charging, the method of variable current intermittent charging is adopted to ensure that the charging current is increased and most of the charging quantity is obtained. At the later stage of charging, a constant voltage charging section is used to obtain the overcharge amount and restore the battery to a fully charged state. Through intermittent stop charging, the battery by the chemical reaction of oxygen and hydrogen combined by absorbing the have time to make the concentration polarization and ohm polarization naturally get eliminated, thus reduce the battery internal pressure, make the next round of constant-current charging can more smoothly, the battery can absorb much more power.
On the basis of variable current intermittent charging method, variable voltage intermittent charging method was proposed, as shown in Figure 8. The difference with variable current intermittent charging method is that the first stage is not intermittent constant current, but intermittent constant voltage. In each constant-voltage charging stage, because it is constant-voltage charging, the charging current naturally decreases in accordance with the exponential law, in line with the characteristics of the acceptability of battery current gradually decreases with the charging process.
Combined with the advantages of pulse charging method, ReflexTM rapid charging method, variable current intermittent charging method and variable voltage intermittent charging method, variable voltage and current wave positive and negative zero pulse intermittent rapid charging method has been developed and applied. Pulse charging method charging circuit control generally has two kinds:
1. The amplitude of pulse current is variable, while the frequency of PWM signal is fixed;
2. The amplitude of pulse current is fixed and the frequency of PWM signal is adjustable.
PWM duty ratio is adjustable, on this basis, join the intermittent stop phase, can be in a shorter time to charge more power, improve the battery charging capacity.