Resistor sampling isolation current detection circuit

Abstract

The invention relates to a resistor sampling isolation current detection circuit. The circuit comprises: a half-bridge circuit and a linear current sensor circuit. The half-bridge circuit comprises: an upper bridge transistor, a lower bridge transistor and a sampling resistor. The linear current sensor circuit comprises: a linear current sensor chip, a bootstrap capacitance charging circuit, a voltage stabilization capacitor and an output pullup resistor. The bootstrap capacitance charging circuit is formed by a diode and a charging capacitor. The current detection circuit of the invention also comprises: a charge pump circuit, a charge pump starting circuit, a photoelectric isolating circuit and a signal processing circuit. An output terminal of the charge pump circuit is respectively connected with a floating power supply terminal and a floating ground terminal of the linear current sensor chip. The charge pump starting circuit provides power for the charge pump circuit through the half-bridge circuit. An input terminal of the photoelectric isolating circuit is connected with the output terminal of the linear current sensor circuit. The output terminal of the photoelectric isolating circuit is connected with the output terminal of the signal processing circuit. After processing a signal, the signal processing circuit transmits the processed signal to a post-stage control circuit. The current detection circuit of the invention is suitable for detecting various kinds of half-bridge circuit currents in an electric power electron technology field.

Description

technical field [0001] The invention relates to a current detection circuit, in particular to a resistance sampling isolation current detection circuit used in a motor control system. Background technique [0002] In the motor control system, the controller needs to measure the current in the winding timely and accurately to realize the current closed-loop control and the design of the current protection circuit, so the current signal needs to be detected. Current detection must be real-time, accurate and reliable, and reliable isolation between the circuit under test and the control circuit is required in the high-voltage system. Usually the Hall current sensor and sampling resistor are used for current detection. The price of the Hall current sensor is relatively high. In some low-cost and low-power occasions, the application of sampling resistor is a good choice. The sampling resistor can directly convert the current signal of the main circuit into a voltage signal and s...

AI Technical Summary

Problems solved by technology

In this case, the input voltage VEE cannot charge the charging capacitor C2 through the diode D1, and the linear current sensor chip 21 cannot work normally.

In high-voltage applications, in order to ensure the safety of electricity use, it is necessary to isolate the power circuit and the control circuit. However, the linear current sensor chip 21 has no isolation function, so its application range is narrow

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