Current detection apparatus for a car power source

• US 20080224665A1
• Filed: 03/13/2008
• Published: 09/18/2008
• Est. Priority Date: 03/16/2007
• Status: Active Grant

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Matsumoto, Akira, Yugou, Masaki
• Granted Patent: US 7,812,570 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: B60R 16/03 for supply of electrical power to vehicle subsystems or for circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: G01R 19/25 using digital measurement techniques
• CPC Class Codes: G01R 31/007 using microprocessors or computers
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3832 without measurement of battery voltage

Abstract

The current detection apparatus is provided with a current detection section (20; 30) that detects charging current and discharging current of the car driving battery (10), a level-shift circuit (40; 50) connected to the output-side of the current detection section (20; 30) that shifts the output of the current detection section (20; 30), and an A/D converter (60) connected to the output-side of the level-shift circuit (40; 50). The level-shift circuit (40; 50) shifts the current detection section (20; 30) output signal to unbalance the maximum discharging current and maximum charging current that can be detected.

Claims

1. A current detection apparatus for a car power source comprising:

a current detection section that detects charging current and discharging current of the car driving battery;

a level-shift circuit connected to the output-side of the current detection section that shifts the output of the current detection section; and

an A/D converter connected to the output-side of the level-shift circuit,

wherein the level-shift circuit shifts the current detection section output signal to unbalance the maximum discharging current and maximum charging current that can be detected.

2. The current detection apparatus for a car power source as cited in claim 1 wherein a battery ECU is provided to control battery discharging current and charging current, and this battery ECU controls larger discharging currents than charging currents.

3. The current detection apparatus for a car power source as cited in claim 1 wherein the level-shift circuit is a difference amplifier;

in the level-shift circuit that is a difference amplifier, current detection section output is input to one Input terminal and a DC compensation voltage is input to the other input terminal to shift the current detection section output signal by the compensation voltage and input it to the A/D converter.

4. The current detection apparatus for a car power source as cited in claim 3 wherein the level-shift circuit is a difference amplifier;

the current detection section output signal is input to the non-inverting side (+side) input terminal and a compensation voltage is input to the inverting side (−

side) input terminal to shift the level of the current detection section output signal.

5. The current detection apparatus for a car power source as cited in claim 4 wherein the level-shift circuit is a difference amplifier with a voltage gain of one.

6. The current detection apparatus for a car power source as cited in claim 1 wherein the level-shift circuit is an adder circuit;

a DC bias voltage is input to the input-side of the adder circuit to shift the current detection section output signal by the DC bias voltage and input it to the A/D converter.

7. The current detection apparatus for a car power source as cited in claim 6 wherein the level-shift circuit is an adder circuit;

the current detection section output signal and a linear bias voltage are both input through resistors to the input-side of the amplifier, and the sum of the current detection section signal and the linear bias voltage is output.

8. The current detection apparatus for a car power source as cited in claim 1 wherein the current detection section has output characteristics showing output voltage increase with discharging current increase, and output voltage decrease with charging current increase.

9. The current detection apparatus for a car power source as cited in claim 1 wherein the current detection section has output characteristics showing linear output voltage increase with battery current increase in the discharging direction.

10. The current detection apparatus for a car power source as cited in claim 1 wherein an amplitude adjustment circuit is provided at the output-side of the level-shift circuit to adjust the amplitude of level-shift circuit output voltage to the input range of the A/D converter.

11. The current detection apparatus for a car power source as cited in claim 10 wherein the amplitude adjustment circuit is an attenuating circuit.

12. The current detection apparatus for a car power source as cited in claim 11 wherein the amplitude adjustment circuit, which is an attenuating circuit, is a resistive voltage divider circuit.

13. The current detection apparatus for a car power source as cited in claim 1 wherein the amplitude adjustment circuit is an amplifying circuit.

14. The current detection apparatus for a car power source as cited in claim 10 wherein the level-shift circuit is an op-amp that serves the dual purpose as an amplitude adjustment circuit, and the amplitude of the level-shift circuit output voltage is adjusted to the input range of the A/D converter by the gain of the op-amp.

15. The current detection apparatus for a car power source as cited in claim 1 wherein the input voltage range of the A/D converter is 0V to 5V.

16. The current detection apparatus for a car power source as cited in claim 1 wherein a computation circuit is connected to the output-side of the A/D converter, and this computation circuit computes battery discharging current and charging current from the digital signal input from the A/D converter.

17. The current detection apparatus for a car power source as cited in claim 16 wherein the computation circuit has a function stored in memory to compute current, and it computes current values corresponding to the input digital signal based on that stored function.