Current sensor

Patent metadata

Field	Value
Publication number	US-11899044-B2
Application number	US-202217875547-A
Country	US
Kind code	B2
Filing date	Jul 28, 2022
Priority date	Aug 17, 2021
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

A current sensor for a detection target current using a shunt resistor includes: a resistance value correction circuit having a correction resistor; a signal application unit that applies an alternating current signal to a series circuit of the shunt resistor and the correction resistor; a voltage detection unit that detects terminal voltages of the shunt resistor and the correction resistor; and a correction unit that calculates a resistance value of the shunt resistor and corrects the resistance value for detection; and a power supply circuit having a first power supply generation unit that generates a first power supply of the signal application unit from an input power supply of an outside; and a second power supply generation unit that generates a second power supply of the voltage detection unit.

First claim

What is claimed is:

1. A current sensor for detecting a detection target current using a terminal voltage of a shunt resistor provided in series in a path through which the detection target current flows and a resistance value for current detection corresponding to a resistance value of the shunt resistor, the current sensor comprising:
a resistance value correction circuit that corrects the resistance value for detection; and
a power supply circuit that supplies an electric power to the resistance value correction circuit,
wherein:
the resistance value correction circuit includes:
a correction resistor connected in series with the shunt resistor in a path different from the path through which the detection target current flows;
a signal application unit that applies an alternating current signal to a series circuit of the shunt resistor and the correction resistor;
a voltage detection unit that detects the terminal voltage of the shunt resistor and a terminal voltage of the correction resistor when the alternating current signal is applied to the series circuit; and
a correction unit that calculates a resistance value of the shunt resistor based on each detection value of the terminal voltage of the shunt resistor and the terminal voltage of the correction resistor detected by the voltage detection unit, and corrects the resistance value for detection based on a calculated resistance value which is the resistance value of the shunt resistor calculated;

the power supply circuit includes:
a first power supply generator that generates a first power supply having a low voltage with respect to an input power supply by stepping down the input power supply supplied from an outside; and
a second power supply generator that generates a second power supply different from the first power supply; and
the power supply circuit is configured to supply the first power supply to the signal application unit and to supply the second power supply to the voltage detection unit,

the signal application unit includes a transistor, a signal generator, and an operational amplifier or a buffer;
the voltage detection unit includes an A/D converter and a synchronous detector or a semiconductor integrated circuit and
the correction unit includes a semiconductor integrated circuit or a micro-computer.

2. The current sensor according to claim 1 , wherein the first power supply generator includes a switching power source.

3. The current sensor according to claim 2 , wherein
the switching power source is configured as an insulation power source in which an input side and an output side are insulated from each other.

4. The current sensor according to claim 1 , wherein
the input power supply is supplied from a main battery that supplies an electric power to a drive unit for traveling a vehicle.

5. The current sensor according to claim 1 , wherein
the input power supply is supplied from an auxiliary battery that supplies an electric power to an auxiliary equipment of a vehicle.

6. The current sensor according to claim 1 , wherein
the second power supply generator includes a linear regulator having a low dropout, and generates the second power supply by the linear regulator.

Assignees

• Denso Corp
• Toyota Motor Co Ltd
• MIRISE Technologies Corporation

Inventors

• Nezuka Tomohiro
• Furuta Yoshikazu
• Wada Shotaro

Classifications

• G01R15/146 Primary

  Measuring arrangements for current not covered by other subgroups of G01R15/14, e.g. using current dividers, shunts, or measuring a voltage drop (if no voltage isolation is involved G01R1/203 or G01R19/0092) · CPC title

• G01R1/071

  containing electro-optic elements · CPC title

• G01R15/242

  based on the Pockels effect, i.e. linear electro-optic effect · CPC title

• G01R15/246

  based on the Faraday, i.e. linear magneto-optic, effect · CPC title

• G01R19/0092

  Measuring current only · CPC title