Universal AC/DC current sensor and isolator

An active universal AC and DC current sensor configured for both AC and DC current measurement comprising:

• a current input configured to receive an incoming AC current waveform and an incoming DC current waveform;
• a current output;
• a first current path between the current input and the current output, the first current path comprising a first resistor;
• a second current path between the current input and the current output parallel to the first current path, the second current path comprising:
• a switch, such that when the switch is closed, current can flow along the second current path between the current input and the current output, and when the switch is opened, current is precluded from flowing along the second current path between the current input and the current output;
• and
• a second resistor in series with the switch;
• a Rogowski coil having an aperture, wherein the second current path passes through the aperture;
• and
• a controller configured to control the switch and to receive a current sensor signal from the Rogowski coil;
• wherein the controller comprises a switching circuit configured to implement a switching pattern that mimics a square wave pulse train with a predetermined duty ratio;
• wherein the controller is further configured to operate in a connected state and a disconnected state;
• wherein, in the disconnected state, the switch is opened;
• and wherein, in the connected state, the switch is closed.

A current sensor for sensing an AC or DC current in a power converter, the power converter having one or more legs, the one or more legs having a current input, a current output, a first current path from the current input to the current output and comprising a first switch, and a second current path from the current input to the current output and comprising a second switch, the current sensor comprising:

• a Rogowski coil having an aperture, wherein the first current path and the second current path pass through the aperture, the Rogowski coil configured to transmit a current sensor signal indicative of a direct current flowing through the first and second current paths;
• a signal conditioning circuit configured to receive the current sensor signal from the Rogowski coil, wherein the signal conditioning circuit comprises:
• a front-end amplifier circuit configured to receive the current sensor signal from the Rogowski coil and generate an amplified current sensor signal;
• an integrator circuit configured to receive the amplified current sensor signal and generate an integrated current sensor signal;
• a rectifier circuit configured to receive the integrated current sensor signal and generate a rectified current sensor signal;
• and
• a low-pass filter circuit configured to receive the rectified current sensor signal and generate a low-pass filtered current sensor signal;
• and
• a controller configured to receive the low-pass filtered current sensor signal and generate a signal indicative of a current flow through the Rogowski coil;
• wherein the first and second switches comprise a semiconductor switch;
• and
• wherein the second current path forms a loop such that when the second switch is closed and the first switch is opened, current passes along the second current path through the aperture in a first direction, and when the first switch is closed and the second switch is opened, current passes along the first current path through the aperture in a second direction opposite the first direction.