ELECTRIC-POWER SUPPLYING DEVICE

摘要

An electric-power supplying device is provided with a first power-supply device and a second power-supply unit that output DC electric power to a DC-supply line, and a controlling means. The first power-supply device conducts a constant-voltage control, using a commercial power-supply. The second power-supply unit is provided with a second power-supply device that conducts ramp control, wherein the output voltage is decreased monotonously as the output current increases, and the above-mentioned output voltage is increased monotonously as the above-mentioned output current decreases. The above-mentioned controlling means outputs command values, when a measurement value (the value of the current that flows through the DC-supply line) is greater than an optimum current value (the value of the current outputted by the above-mentioned first power-supply device into the above-mentioned DC-supply line, when the conversion efficiency of the above-mentioned first power-supply device is maximum), so as to make the value of the current that the above-mentioned second power-supply unit outputs to the above-mentioned DC-supply line becomes equal to the value of the difference between the above-mentioned measurement value and the above-mentioned optimum current value. The above-mentioned second power-supply device configures the value of the above-mentioned output current to a value corresponding to the above-mentioned command value, without changing the above-mentioned output voltage, by changing the conditions of the above-mentioned ramp control.