# US 7,609,050 B2 · Method and system for determing current in an electrical component in a power conversion system

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- Number: US 7,609,050 B2
- Document ID: US7609050B2
- Status: Granted
- Kind: B2
- Application number: 11/676,576
- Filed: 2007-02-20
- Published: 2008-08-21
- Granted: 2009-10-27
- Earliest claimed: 2007-02-20
- Assignees: GM Global Technology Operations LLC
- Inventors: Constantin C. Stancu; Daniel L. Kowalewski
- Web page: https://patentgrep.com/patent/US7609050B2

## CPC

- G01R 19/0092: {Measuring current only}
- H02M 3/1582: {Buck-boost converters (H02M3/1584 takes precedence)}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)

## Abstract

A method and system for determining a current flowing through an electrical component are provided. A switch electrically coupled to the electrical component and two voltage sources is activated. The activation of the switch causes current to flow through the electrical component after an amount of time. The amount of time between said activating the switch and the flow of current through the electrical component is determined. The current flowing through the electrical component is measured to determine a measured current value. The measured current value is modified based at least in part on the amount of time between said activating the switch and the flow of current through the electrical component.

## Claims

### Claim 1

A method for determining a current flowing through an electrical component comprising:
activating a switch electrically coupled to the electrical component and two voltage sources causing current to flow through the electrical component;
determining an amount of time between said activating the switch and the flow of current through the electrical component;
measuring the current flowing through the electrical component to determine a measured current value; and
modifying the measured current value based at least in part on the amount of time.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
generating an acquisition signal having at least one acquisition duty cycle; and
generating a switch signal having at least one switch duty cycle;
wherein each of the at least one acquisition duty cycle and the at least one switch duty cycle have a beginning-point, a mid-point, and an end-point, and the mid-point of the at least one switch duty cycle occurs substantially simultaneously with the end-point of the at least one acquisition duty cycle.

### Claim 3 (depends on 2)

The method of claim 2, wherein said activating the switch occurs substantially simultaneously with the beginning-point of the at least one switch duty cycle.

### Claim 4 (depends on 3)

The method of claim 3, wherein the measuring of the current flowing through the electrical component occurs substantially simultaneously with the end-point of the at least one acquisition duty cycle.

### Claim 5 (depends on 4)

The method of claim 4, wherein the electrical component is an inductor having an inductance and the two voltage sources comprise a first voltage source generating a first voltage and a second voltage source generating a second voltage.

### Claim 6 (depends on 5)

The method of claim 5, wherein the modifying of the measured current value comprises calculating a current error.

### Claim 7 (depends on 6)

The method of claim 6, wherein the calculating the current error comprises:
determining a difference between the first voltage and the second voltage;
dividing the difference between the first voltage and the second voltage by the inductance of the inductor to calculate a slope of the measured current value; and
multiplying the slope of the measured current value by the amount of time between said activating the switch and the flow of current through the electrical component.

### Claim 8 (depends on 7)

The method of claim 7, wherein the switch and the inductor are within a direct current-to-direct current (DC/DC) converter.

### Claim 9 (depends on 8)

The method of claim 8, wherein the DC/DC converter further comprises at least one filter, the at least one filter comprising a capacitor and a filter inductor.

### Claim 10 (depends on 9)

The method of claim 9, wherein the first voltage source is a battery and the second voltage source is a fuel cell.

### Claim 11

A method for determining a current flowing through an electrical component within a direct current-to-direct current (DC/DC) converter in an automobile comprising:
generating an acquisition signal having at least one acquisition duty cycle having a beginning-point, a mid-point, and an end-point;
generating a switch signal having at least one switch duty cycle having a beginning-point, a mid-point, and an end-point, the mid-point of the switch duty cycle occurring substantially simultaneously with the end-point of the at least one acquisition duty cycle;
activating a switch electrically coupled to the electrical component and two voltage sources substantially simultaneously with the beginning point of the switch duty cycle, said activating the switch causing the current to flow through the electrical component after an amount of time;
determining the amount of time between said activating the switch and the flow of current through the electrical component;
measuring the current flowing through the electrical component substantially simultaneously with the mid-point of the switch duty cycle to determine a measured current value; and
modifying the measured current value based at least in part on the amount of time between said activating the switch and the flow of current through the electrical component.

### Claim 12 (depends on 11)

The method of claim 11, wherein the electrical component is an inductor having an inductance and the two voltage sources comprise a first voltage source generating a first voltage and a second voltage source generating a second voltage.

### Claim 13 (depends on 12)

The method of claim 12, wherein the modifying of the measured current value comprises:
determining a difference between the first voltage and the second voltage;
dividing the difference between the first voltage and the second voltage by the inductance of the inductor to calculate a slope of the measured current value; and
multiplying the slope of the measured current value by the amount of time between said activating the switch and the flow of current through the electrical component.

### Claim 14 (depends on 13)

The method of claim 13, wherein the switch is an insulated gate bipolar transistor (IGBT).

### Claim 15 (depends on 14)

The method of claim 14, wherein the first voltage source is a battery and the second voltage source is a fuel cell.

### Claim 16

An automotive drive system comprising:
a power converter configured to be coupled to a first voltage source and a second voltage source, the power converter comprising a switch and an inductor having an inductance;
an electric motor coupled to the power converter; and
a microprocessor in operable communication with the power converter, the microprocessor being configured to:
activate the switch to cause current to flow through the inductor after an amount of time;
determine the amount of time between the activation of the switch and the flow of current through the inductor;
determine a measured current value of the current flowing through the inductor; and
modify the measured current value based at least in part on the amount of time between the activation of the switch and the flow of current through the inductor.

### Claim 17 (depends on 16)

The automotive drive system of claim 16, wherein the power converter is a direct current-to-direct current (DC/DC) converter.

### Claim 18 (depends on 16)

The automotive drive system of claim 16, wherein the microprocessor is further configured to:
generate an acquisition signal having at least one acquisition duty cycle; and
generate a switch signal having at least one switch duty cycle;
wherein each of the at least one acquisition duty cycle and the at least one switch duty cycle have a beginning-point, a mid-point, and an end-point, the mid-point of the at least one switch duty cycle occurs substantially simultaneously with the end-point of the at least one acquisition duty cycle, the activation of the switch occurs substantially simultaneously with the beginning-point of the at least one switch duty cycle, and the measurement of the current flowing through the electrical component occurs substantially simultaneously with the end-point of the at least one acquisition duty cycle.

### Claim 19 (depends on 18)

The automotive drive system of claim 18, wherein the modification of the measured current value comprises:
determining a difference between the first voltage and the second voltage;
dividing the difference between the first voltage and the second voltage by the inductance of the inductor to calculate a slope of the measured current value; and
multiplying the slope of the measured current value by the amount of time between said activating the switch and the flow of current through the electrical component.

### Claim 20 (depends on 19)

The automotive drive system of claim 19, wherein the first voltage source is a battery and the second voltage source is a fuel cell.
