Abstract: A device for measuring electrical current in a line may include, among other things, a Hall effect sensor wherein a first response is generated by electrical current in the line; a current transformer disposed with the line extending axially therethrough and connected in series to the Hall effect sensor wherein a second response is generated by the electrical current in the line. An equalizer may be connected to the Hall effect sensor and to the current transformer and may be configured to flatten the first and second responses relative to each other. The permeability magnetic path length and cross section of the current transformer is selected such that low frequency roll-off of the current transformer is at a lower frequency than high frequency roll-off of the Hall effect sensor.

Abstract: A three phase inverter consisting of three single phase legs using either switch mode or linear control is fed by a DC-DC converter to provide input output isolation. This requires that the DC-DC converter delivers equal positive and negative voltages to the single phase legs to allow each output to generate a high fidelity sine wave outputs to the load. By measuring the error voltages on the positive output, the negative output and the total output of the DC-DC converter it is possible to control a single duty cycle while maintaining all three output voltages within the limits required by the DC-AC phase legs. This significantly reduces the cost and complexity of the DC-DC converter and eliminates the need to use a fourth phase leg to generate the neutral connection for a three phase output.

Abstract: A device for measuring electrical current in a line may include, among other things, a Hall effect sensor wherein a first response is generated by electrical current in the line; a current transformer disposed with the line extending axially therethrough and connected in series to the Hall effect sensor wherein a second response is generated by the electrical current in the line. An equalizer may be connected to the Hall effect sensor and to the current transformer and may be configured to flatten the first and second responses relative to each other. The permeability magnetic path length and cross section of the current transformer is selected such that low frequency roll-off of the current transformer is at a lower frequency than high frequency roll-off of the Hall effect sensor.

Abstract: A three phase inverter consisting of three single phase legs using either switch mode or linear control is fed by a DC-DC converter to provide input output isolation. This requires that the DC-DC converter delivers equal positive and negative voltages to the single phase legs to allow each output to generate a high fidelity sine wave outputs to the load. By measuring the error voltages on the positive output, the negative output and the total output of the DC-DC converter it is possible to control a single duty cycle while maintaining all three output voltages within the limits required by the DC-AC phase legs. This significantly reduces the cost and complexity of the DC-DC converter and eliminates the need to use a fourth phase leg to generate the neutral connection for a three phase output.