Switching DC power supply apparatus
AssigneeCanon Kabushiki Kaisha
InventorsMasayoshi Saito, Takashi Birumachi
Life of this patent
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Abstract
A DC power supply apparatus includes a switching transformer having a switching element, a primary current detection circuit, arranged on a primary side of the transformer, for detecting a current flowing in the switching element, a secondary current detection circuit for detecting an output current from a secondary side of the transformer, and a control circuit for controlling the switching element on the basis of outputs from the primary and secondary current detection circuit.
Claims13
A DC power supply apparatus comprising:
- a switching transformer having a switching element;
- primary current detection means, arranged on a primary side of said transformer, for detecting a current flowing in said switching element;
- secondary voltage detection means, arranged on a secondary side of said transformer, for detecting an output voltage of the secondary side;
- feedback means for feeding back the detected output voltage detected by said secondary voltage detection means to said switching element to maintain the output voltage at a constant value;
- secondary current detection means for detecting an output current from said secondary side of said transformer;
- and
- control means for controlling said switching element on the basis of outputs from said primary and second current detection means such that the output current detected by said secondary current detection means does not exceed a predetermined level.
A switching DC power supply for a constant voltage, having a secondary voltage detection circuit, arranged on a secondary side of a transformer, for detecting an output voltage of the secondary side, a feedback circuit for feeding back the detected output voltage detected by said secondary voltage detection circuit to a switching element at a primary side, and an overcurrent protective circuit for controlling a DC output current by controlling a driving pulse to said switching element, wherein said overcurrent protective circuit comprises primary current detection means, constituted by a comparator for detecting a peak current value of said switching element for every switching period and operating on the basis of the detected peak current value, and secondary current detection means for detecting DC outputs currents and operating on the basis of an average value of the DC output currents, so that a threshold value of said comparator is offset by an output from said secondary current detection means.
A switching DC power supply apparatus for converting an AC current, generated by turning on and off an DC input using a switching element, into a DC current, and supplying the DC current to a load, comprising:
- current detection means for detecting a current flowing in said switching element;
- threshold value setting means for setting an overcurrent detection threshold value of said switching element;
- offset means for offsetting the threshold value in accordance with a type of the load;
- and
- control means for comparing an output from said current detection means with the offset threshold value to obtain a comparison signal, and controlling a switching operation of said switching element by using the comparison signal.
A switching DC power supply apparatus for converting an AC current, generated by turning on and off an DC input using a switching element, into a DC current, and supplying the DC current to a load, comprising:
- current detection means for detecting a current flowing in said switching element;
- threshold value setting means for setting an overcurrent detection threshold value of said switching element;
- offset means for offsetting the threshold value in accordance with an operation state of the load;
- and
- control means for comparing an output from said current detection means with the offset threshold value to obtain a comparison signal, and controlling a switching operation of said switching element by using the comparison signal.
A switching DC power supply apparatus for converting an AC current, generated by turning on and off a DC input using a switching element, into a DC current, and supplying the DC current to a plurality of loads, comprising:
- current detecting means for detecting a current flowing in said switching element;
- overload detection means for detecting an overload state of any of the plurality of loads;
- offset means for offsetting an output from said current detection means in accordance with an output from said overload detection means;
- and
- control means for controlling a switching operation of said switching element on the basis of an output from said offset means.
Dependencies are inferred from the claim text.