Current detecting circuit based on bi-directional saturation current sensor and driving method thereof

Abstract

The invention discloses a current detecting circuit based on a bi-directional saturation current sensor and a driving method thereof. The current detecting circuit is composed of a magnetic ring current sensor, an H-bridge current detecting circuit and a bridge arm power device driving circuit. The current sensor is used for achieving a high-temperature-resistant operational capability and an isolation function. The H-bridge current detecting circuit makes the secondary side of the current sensor bidirectional saturation, compensates influences of positive and negative residual magnetism on current detection, and eliminates errors of the positive and negative residual magnetism along with temperature drift. A comparator and a D trigger are used for achieving rapid response. Compared with a conventional current detecting circuit, the current detecting circuit of the invention has a high-temperature-resistant operational capability, an isolation function, fast response and high precision, and is suitable for detecting the current of high-temperature-resistant motor driver based on SiC MOSFETs.

Description

technical field [0001] The invention relates to a high temperature resistant current detection circuit, in particular to a high temperature resistant current detection circuit based on a bidirectional saturated current sensor. It belongs to the field of power electronics. Background technique [0002] In the control strategy of the motor driver, the switching frequency of the power device is directly derived from the sense current. Therefore, Si-based converters use current detection methods such as Hall sensors and resistor shunts to realize current detection. [0003] With the rapid development of new SiC devices, motor drivers based on SiC devices can be widely used in high-temperature applications such as electric aircraft, electric vehicles, and oil drilling, where the working environment temperature exceeds 200 °C. However, limited by the temperature, the current detection method based on the Si converter is difficult to apply to the SiC-based high temperature conver...

AI Technical Summary

Problems solved by technology

The Hall effect sensor is based on a Hall-type device located in the air gap of the magnetic core to detect DC or tens of kHz AC components, but the Hall element is difficult to withstand a high temperature environment above 200°C.

[0006] Summarizing the above current detection methods, it can be seen that the current detection methods of Si-based converters are difficult to meet the reliable high-temperature working ability, high precision, low loss, isolation and AC / DC detection capabilities of SiC-based high-temperature converters.

The current sensor made of magnetic ring can meet the requirements of SiC-based high-temperature resistant converters. The coercive force of the ideal magnetic element is zero, but the remanence and coercive force of the magnetic material of the actual current sensor will cause errors in the detection current, which need to be eliminated. Effect of Coercive Force Hc on Detection Current

In addition, the B-H curve of the magnetic material drifts with the temperature, so that the detection current is greatly affected by the temperature, so it is necessary to compensate the temperature difference for the detection current

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