Load drive current control method and system
The present disclosure relates to a battery load drive system, and more particularly, to a battery load drive system for preparing for a surge current generated by a capacitor when a battery is coupled to a battery using a path for reducing current additionally provided in an existing path.
1. A method of controlling a drive current supplied to a load when the load is connected to a battery, the method comprising:
outputting an initial PWM signal having a predetermined initial duty ratio and an initial period, wherein the initial PWM signal is an initial switching control signal of a switch for turning on/off an initial current flow between the load and the battery to supply an initial current to the load; and
measuring a load voltage of the load while the initial current is supplied to the load;
measuring a battery voltage of the battery;
calculating a difference between the measured battery voltage and the load voltage measured while the initial current is supplied to the load;
if the difference between the measured battery voltage and the load voltage measured while the initial current is supplied to the load is less than a predetermined reference value, continue outputting PWM signals at the initial duty ratio; and
if the difference between the measured battery voltage and the load voltage measured while the initial current is supplied to the load is greater than the predetermined reference value, outputting subsequent PWM signals at either: a duty ratio that is greater than the initial duty ratio, or a period that is longer than the initial period.
2. The method of claim 1 , further comprising:
repeatedly:
measuring the load voltage of the load;
measuring the battery voltage of the battery;
calculating the difference between the measured battery voltage and the load voltage measured; and
outputting the subsequent PWM signal,
until the difference between the measured battery voltage and the measured load voltage becomes less than the predetermined reference value.
3. The method of claim 1 , wherein the predetermined initial duty ratio of the initial PWM signal is determined by a size of a capacitance of a capacitor included in the load.
4. The method of claim 3 , wherein the initial current supplied to the load by the initial PWM signal charges the capacitor included in the load.
5. The method of claim 2 , wherein the duty ratio or the period of the subsequent PWM signal is increased gradually if the difference between the repeatedly measured battery voltage and the repeatedly measured load voltage remains greater than the predetermined reference value.
6. A system for controlling a drive current supplied to a load when the load is connected to a battery, the system comprising:
a battery configured to be a current source;
a control unit comprising a PWM signal output unit configured to output an initial PWM signal having an initial predetermined duty ratio;
a discharge switching unit comprising a switch configured to turn on/off a current flowing from the battery to the load based on the duty ratio of the PWM signal outputted from the control unit;
a voltage measurement unit configured to measure:
a voltage of the battery; and
a voltage of the load from an initial current supplied to the load by the initial PWM signal;
a voltage difference calculation unit configured to calculate a difference between the measured voltage of the battery and the measured voltage of the load; and
a voltage determination unit configured to determine whether the voltage difference calculated in the voltage difference calculation unit is less than a predetermined reference value,
wherein:
if the voltage difference is greater than the predetermined reference value, the PWM signal output unit is configured to output a correction PWM signal by increasing either the initial duty ratio or the initial period; and
if the voltage difference is less than the predetermined reference value, the PWM signal output unit is configured to continue outputting PWM signals at the initial duty ratio and the initial period.
7. The system of claim 6 , wherein the load comprises a capacitor.
8. The system of claim 6 , wherein the PWM signal output unit is configured to output an initial PWM signal having a predetermined initial duty ratio at a first execution.
9. The system of claim 8 , wherein the predetermined initial duty ratio of the initial PWM signal is preset based on a size of a capacitance of a capacitor included in the load.
10. The system of claim 9 , wherein the initial current supplied to the load by the initial PWM signal charges the capacitor included in the load.
11. The system of claim 6 , wherein if the voltage difference remains greater than the predetermined reference value, the PWM signal output unit is configured to increase the one of the duty ratio and the period of the previously-outputted PWM signal gradually.