| 摘要 |
PROBLEM TO BE SOLVED: To provide a PWM current detection device for obtaining an instantaneous value of an alternative current waveform superimposing a direct current component by precisely estimating and calculating by means of the output waveform, not using a direct current magnetic flux detection means such as a Hall element. SOLUTION: The device is provided with a pressing element series circuit to be energized in one way by on-off control, an encirculating element to be energized in one way and connected in reverse-parallel to the pressing element, a current transformer for detecting only the alternating component of current flowing to load, for detecting the current flowing to load when the pressing element is PWM controlled, by connecting DC power source to both ends of the pressing element series circuit, connecting one end of the load to the mutual connecting points of the pressing element, and connecting the other end of the load to a prescribed point regarded as the voltage range of the DC power source, and a detected value correction means for correcting the detected value of the current transformer to be output, executing semidriven PWM control for a prescribed region including the region where current flows to the encirculating element by the induction of load and regarding the detected value of which the absolute value of the time variation rate of the current transformer is regarded substantially zero to be a zero level of the current flowing to load. |
