A Current Transducer with Digital Output for Motor Drive

Analysis and Compensation of Phase Shift Errors of an Open-Loop Current Transducer Considering Eddy Current

“…The current transducer consists of a C-type magnetic core with an air gap, which concentrates the magnetic field generated by the primary current to be measured, creating a high and uniform magnetic field in the air gap. The resultant magnetic field is then measured and converted into a current value, thereby facilitating the measurement of the primary current [4], [5].…”

“…With the simplest structure comprising only a magnetic core and a Hall sensor, as shown in Fig. 1, the open-loop current transducer is cost-effective and robust, making it particularly suitable for applications demanding high reliability, such as EV inverters [4], [5]. The magnetic core of the current transducer is composed of soft magnet material with high magnetic permeability.…”

“…where 𝑥, 𝑐, and 𝑤 denote magnetic core shape, 𝜙 is the magnetic flux in the core in Fig. 3, 𝐵 𝑎 is flux density in the magnetic core, 𝜌 is the resistivity of the magnetic core, and current in the magnetic core is expressed as (4).…”

“…This transducer operates by inducing a magnetic field through current measurement on the primary side, with the field concentrated on the C-type magnetic core. An air gap within the core houses the Hall sensor, which detects the magnetic field and outputs it as voltage [4]. Traction motors in applications such as contemporary electric vehicles (EV) often operate at high speeds, necessitating measurement of the higher frequency by the current transducer.…”

“…To mitigate phase shift errors, options such as employing open-loop current transducers made of powdered magnetic materials or closed-loop and flux gate types are available. Nevertheless, for high-current measurement, environmental robustness, and cost-effectiveness, an open-loop current transducer with a simple structure and a highly reliable electrical steel magnetic core is preferred [4].…”