Overload and short-circuit sensing circuit and converter protecting circuit and method

A converter protecting circuit comprising:

• an overcurrent sensing unit sensing a primary current of a converter;
• a voltage level adjusting unit adjusting a voltage level of the sensed primary current;
• a rectifying unit rectifying the signal adjusted by the voltage level adjusting unit;
• a short-circuit sensing unit sensing a current induced to a primary side of the converter due to a short-circuit or an overcurrent at a secondary side of the converter, separately from the overcurrent sensing unit;
• a delay unit delaying the signal provided from the rectifying unit and the induced current sensing signal provided from the short-circuit sensing unit;
• an overcurrent judging unit receiving the signal from the delay unit, comparing the received signal with a first reference signal, judging whether or not an overcurrent has been generated and outputting a judgment result;
• a short-circuit judging unit connected in parallel with the overcurrent judging unit, receiving the signal from the delay unit, judging whether or not a short-circuit has been generated and outputting a judgment result;
• and
• a protection unit outputting an auto restart signal at the time of the overcurrent and outputting a system protection signal at the time of the short-circuit, depending on the signals output from the overcurrent judging unit and the short-circuit judging unit.

A converter protecting method comprising:

• a sensing, level adjusting and rectifying step of sensing a primary current in order to judge an overcurrent at a primary side of a converter or sensing an induced current induced to the primary side due to a short-circuit or an overcurrent at a secondary side of the converter separately from sensing the primary current, adjusting a voltage level of the primary current sensed at the time of sensing the primary current, and rectifying a signal of which the voltage level is adjusted;
• a delay step of delaying the signal rectified depending on the sensing of the primary current or the induced current sensed depending on the sensing of the induced current;
• an overcurrent and short-circuit judging step of receiving the signal provided from the delay step, comparing the received signal with a first reference signal, judging whether or not an overcurrent has been generated and outputting a judgment result, and at the same time, separately, receiving the signal provided from the delay step, judging whether or not a short-circuit has been generated and outputting a judgment result;
• and
• a protection signal outputting step of outputting an auto restart signal at the time of the overcurrent and outputting a system protection signal at the time of the short-circuit, depending on the signal output from the overcurrent and short-circuit judging step.