DC-DC CONVERTER
A DC-DC converter, which controls the output voltage supplied to a load at a desired magnitude by performing on/off control of the input voltage using a switch, includes: an error amplifier for outputting the difference voltage between the output voltage and a preset reference voltage; and a plurality of phase compensation circuits for compensating the phase of the output voltage fed back to the error amplifier with different characteristics, whereby the DC-DC converter is configured such that changes in either the input voltage or in the load current flowing into the load are detected, and switching between the plurality of phase compensation circuits is performed. The frequency characteristic of each of the phase compensation circuits is determined for each of a plurality of demarcated fluctuation ranges of the input voltage or the load current.
1 . A DC-DC converter, which controls a DC output voltage supplied to a load circuit at a desired magnitude by performing on/off control of a DC input voltage using switching device, comprising:
an error detection device, which outputs a difference voltage between the DC output voltage and a preset reference voltage;
a phase compensation device, comprising a plurality of phase compensation circuits which use different characteristics to perform compensation of the phase of the DC output voltage fed back to the error detection device; and
a switching control device, which detects changes in either the DC input voltage or in a load current flowing into the load circuit, and switches between the plurality of phase compensation circuits constituting the phase compensation device,
wherein each of frequency characteristics of the phase compensation circuits is determined for each of a plurality of demarcated fluctuation ranges of the DC input voltage or the load current flowing into the load circuit.
2 . The DC-DC converter according to claim 1 , wherein the switching control device modifies the frequency characteristic of the error detection device by switching the phase compensation device according to whether the DC input voltage is higher or lower than a preset voltage value.
3 . The DC-DC converter according to claim 2 , wherein switching of the phase compensation device is provided with a hysteresis characteristic.
4 . The DC-DC converter according to claim 1 , wherein the switching control device detects only changes in the DC input voltage.
5 . The DC-DC converter according to claim 1 , wherein the switching control device modifies the frequency characteristic of the error detection device by switching the phase compensation device according to whether the load current flowing into the load circuit is higher or lower than a reference current value.
6 . The DC-DC converter according to claim 5 , wherein switching of the phase compensation device is provided with a hysteresis characteristic.
7 . The DC-DC converter according to claim 1 , wherein the switching control device detects only changes in the load current flowing into the load circuit.
8 . The DC-DC converter according to claim 1 , wherein the switching control device simultaneously detects changes in the DC input voltage and changes in the load current.
9 . The DC-DC converter according to claim 1 , wherein the phase compensation device comprises a phase compensation circuit having at least two different frequency characteristics determined either by analysis using a state averaging equation or by an experimental device.
10 . The DC-DC converter according to claim 9 , wherein the phase compensation device is configured by a phase compensation circuit having two different frequency characteristics.
11 . The DC-DC converter according to claim 10 , wherein the DC output voltage is fed back to the error detection device via a voltage-dividing resistance circuit comprising the phase compensation circuit.
12 . The DC-DC converter according to claim 10 , wherein the error detection device has an error amplifier, and as the phase compensation circuit, a phase compensation resistor and a phase compensation capacitor are series-connected between an output terminal and an inverting input terminal of the error amplifier which outputs the difference voltage.
13 . The DC-DC converter according to claim 1 , wherein the switching device is provided so as to output the DC output voltage which is stepped-up with respect to the DC input voltage.
14 . The DC-DC converter according to claim 1 , wherein the switching device is provided so as to output the DC output voltage which is stepped-down with respect to the DC input voltage.
15 . The DC-DC converter according to claim 1 , wherein the switching device is provided so as to output the DC output voltage which is inverted in polarity with respect to the DC input voltage.