Charging control device and voltage detecting method for eliminating switch internal resistance by voltage clamping

Abstract

The invention discloses a voltage detecting method, circuit and charger for eliminating switch internal resistance by voltage clamping. The method comprises the following steps of: setting a clamping voltage setting point at the cathode end of a charging battery so that the cathode voltage of the charging battery is stabilized in a clamping voltage value; detecting an anode voltage value of the charging battery in real time and comparing the expected saturation voltage values of the charging battery with the anode voltage value; if the anode voltage value is smaller than the sum of the clamping voltage value and the expected saturation voltage values, keeping on charging; and if the anode voltage value is larger than or equal to the sum of the clamping voltage value and the expected saturation voltage values, outputting a switching-off signal for switching off a first switch and stopping charging. The practical voltage values at both ends of the battery can be detected by setting theclamping voltage value at the cathode end of the charging battery, detecting the anode voltage value of the charging battery in real time and subtracting the clamping voltage value by the anode voltage value of the charging battery, the measuring result is accurate and is free from the influence of the internal resistance of a switching tube.

Description

Technical field [0001] The invention relates to the field of electronics, in particular to a charging control device and a voltage detection method for eliminating internal resistance of a switch by voltage clamping. Background technique [0002] See figure 1 In the charging circuit of the universal charger, due to the need to switch the battery polarity, there is generally a switch between the two ends of the battery to the power supply and the reference ground. Whether this switch is a mechanical switch, a triode, or a field effect tube, a switch will be introduced The parasitic resistance. [0003] See figure 2 During the charging process, the voltage of the rechargeable battery needs to be continuously detected to determine whether the battery is saturated. Because it is difficult to directly measure the voltage across the battery in the circuit system, it is often used to directly detect the positive terminal voltage VP of the battery as the judgment voltage. The switch is g...

AI Technical Summary

Problems solved by technology

[0003] see figure 2 In the process of charging, it is necessary to continuously detect the voltage of the rechargeable battery to judge whether the battery is saturated. Since it is difficult to directly measure the voltage at both ends of the battery in the circuit system, it is often used to directly detect the positive terminal voltage VP of the battery as the judgment voltage, because the negative terminal of the battery The switch is grounded, so VP=Ich*RK+VBAT, where VBAT is the actual battery voltage, and Ich is the charging current. It can be seen that due to the existence of the switch parasitic resistance RK, the measured positive terminal voltage is different from the actual battery voltage. error

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