Requirements for charging stations for electric vehicles

In the future, the charging station should be able to meet the following points according to the characteristics of the battery and the requirements of the battery:

A (2)

(1) For a battery that has been completely discharged, it should be charged with a large current at the initial stage of charging to achieve rapid purpose. During the first 15 minutes of fast charging, 50% to 80% of the total capacity can be charged.

(2) In order to achieve fast and high efficiency, the charger should adopt a pulse circuit.

(3) When the battery is charged to a certain level, that is, when the battery is charged to a certain turning point, the current should be reduced in a timely manner.

(4) In order to prevent polarization and gas production during the charging process, reduce the charging efficiency, decompose and concentrate the electrolyte, and heat and vulcanize the electrode plates, negative pulses should be added to eliminate polarization in a timely manner. When the depolarization is completed, the predetermined effect is produced after the test, and the battery plate has been restored to the original good state of charge, the discharge should be automatically stopped and automatically transferred to the state of charge again.

(5) The generation of negative pulses must not only be timely, but also of moderate intensity, not excessive or weak. For this reason, the circuit should have a detection function. When the depolarization is not complete, the discharge should be supplemented until the polarization phenomenon is completely eliminated.

(6) The charger circuit shall have the function of automatically detecting and controlling the charging voltage, and its final voltage shall not exceed the specified charging termination voltage of the battery.

(7) Constant current is relative, and constant voltage is absolute. This not only describes the charging process, but also an absolute requirement for the final stage of charging. The voltage must be based on the battery’s charge-discharge termination voltage. In the final stage of charging, as the gap between the charger voltage and the battery voltage is getting smaller and smaller, the charging current is finally terminated. Therefore, the maximum voltage limit of the charger should be very accurate. Only below the maximum limit can the current be gradually reduced. When charging to the turning point of this type of battery, the current must be adjusted immediately. At the last turning point, the charger should be able to automatically switch to very small current charging, which is the usual trickle method. The trickle is still pulse width modulation, but the duty cycle is much smaller. The trickle of lead-acid batteries should be below C/16.

(8) After the charge reaches the specified end of charge and the trickle charge is completed, the battery plates in the battery pack are completely restored, and each single shelf is balanced with each other, and the charger can automatically cut off the power to stop charging.

(9) In terms of display: there are power supply, charging, status display of each stage, display of charged power, etc.

(10) There is reverse connection and short circuit protection.

(11) The temperature drift is small, the voltage temperature coefficient of the device should be low, and the voltage is not unstable due to changes in the ambient temperature. This is the condition to ensure the accuracy of the final voltage.

(12) The clutter and harmonics of the electric vehicle charger circuit must meet the requirements, and the clutter and harmonics are not allowed to feed back to the grid

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Post time: Mar-31-2021