Electric current sensor, electric current measurement device, and electric current measurement method

An electric current sensor comprising:

• a shield having an opening for capturing a magnetic field in the shield, the magnetic field having been generated by an electric current flowing through a conductor;
• a magnetic field sensor that is placed at a position in the shield and outputs a sensor voltage corresponding to the magnetic field at the position;
• a detection circuit that is placed outside the shield and detects the electric current on the basis of the sensor voltage from the magnetic field sensor;
• and
• a movement mechanism that moves the magnetic field sensor, wherein
• the magnetic field sensor includes:
• a first magnetic field sensor that is placed near the opening and is to detect high-frequency magnetic fields;
• and
• a second magnetic field sensor to detect high-frequency magnetic fields, and
• the movement mechanism moves the second magnetic field sensor between a position near the opening and a position far from the opening.

An electric current measurement device comprising:

• a shield having an opening for capturing a magnetic field in the shield, the magnetic field having been generated by an electric current flowing through a conductor;
• a magnetic field sensor that is placed at a position in the shield and outputs a sensor voltage corresponding to the magnetic field at the position;
• a detection circuit that is placed outside the shield and generates, on the basis of the sensor voltage from the magnetic field sensor, a detection voltage indicating a value of the electric current;
• and
• an external device that is placed outside the shield and corrects the detection voltage in a frequency domain.

An electric current measurement method comprising:

• detecting a magnetic field at a position by using a magnetic field sensor placed at the position in a shield having an opening for capturing the magnetic field in the shield, the magnetic field having been generated by an electric current flowing through a conductor;
• and
• detecting the electric current on the basis of a detection result from the magnetic field sensor, wherein
• the magnetic field sensor includes:
• a first magnetic field sensor to detect low-frequency magnetic fields;
• and
• a second magnetic field sensor to detect high-frequency magnetic fields,
• the first magnetic field sensor is arranged nearer to the opening than the second magnetic field sensor, and
• the second magnetic field sensor is arranged farther from the opening than the first magnetic field sensor.