| 摘要 |
DC current from a DC source 71 is measured by means of a direct current current transformer (CT) 40 having a drive transformer 45 coupled to a pair of switches 10, 11 connected to the primary windings 41, 42 of the CT 40. The drive transformer is driven by a drive signal generator 72 that controls the switching on or off of the switches 10, 11. The switches 10, 11 thus chop or commutate the DC signal into an AC signal that can be detected on the secondary side of the CT 40. Further switches 12, 13 on the secondary side may be controlled by the same drive transformer to provide an output via load resistor 21 and terminals 64, 65. The switches may be MOSFETs and the drive signal may be a square wave of 50% duty cycle. The CT can therefore measure DC signals without core saturation and may be used to measure current in a DC-DC converter whilst maintaining galvanic isolation. |
