# US 10,481,207 B2 · Switching amplifier and method for estimating remaining lifetime of a switching amplifier

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- Number: US 10,481,207 B2
- Document ID: US10481207B2
- Status: Granted
- Kind: B2
- Application number: 15/471,555
- Filed: 2017-03-28
- Published: 2017-09-28
- Granted: 2019-11-19
- Earliest claimed: 2016-03-28
- Assignees: General Electric Company
- Applicants: General Electric Company
- Inventors: Juan Antonio Sabate; Louis Frigo; Pengcheng Zhu; Melissa Freeman; Margaret Wiza; Syedsaad Ali; Fei Xu; Xi Lu; Tao Wu; Ruxi Wang
- Web page: https://patentgrep.com/patent/US10481207B2

## CPC

- G01R 31/3277: {of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches}
- G01K 7/42: Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature
- G01R 31/2633: {for measuring switching properties thereof}
- G01R 31/44: Testing lamps
- H03F 1/523: {for amplifiers using field-effect devices (H03F1/526 takes precedence)}
- H03F 3/2178: {using more than one switch or switching amplifier in parallel or in series (H03F3/2173, H03F3/2175 take precedence)}
- G01K 2217/00: Temperature measurement using electric or magnetic components already present in the system to be measured
- G01R 33/3852: {Gradient amplifiers; means for controlling the application of a gradient magnetic field to the sample, e.g. a gradient signal synthesizer}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)
- H03F: AMPLIFIERS

## Abstract

A switching amplifier includes a power device and a processing device. The power device is configured for powering a load and is comprised of a plurality of switches. The processing device configured to calculate a switch junction temperature for a bonding wire in each switch based at least in part on a power loss of each switch; generate a first accumulated fatigue damage of the bonding wire in each switch based on the switch junction temperature; and generate an estimated remaining lifetime of the switching amplifier based on the first accumulated fatigue damages of the bonding wires in each switch.

## Claims

### Claim 1

A switching amplifier, comprising:
a power device for powering a load and comprised of a plurality of switches, wherein each of the plurality of switches is coupled in parallel with a diode; and
a processing device configured to:
calculate a switch junction temperature for a bonding wire in each switch based at least in part on a power loss of the switch;
generate a first accumulated fatigue damage of the bonding wire in each switch based on the switch junction temperature;
calculate a case temperature for a solder layer in each switch based at least in part on an average value of the power loss of the switch and a power loss of the corresponding diode;
generate an accumulated fatigue damage of the solder layer in each switch based on the case temperature; and
generate an estimated remaining lifetime of the switching amplifier based on at least one of the first accumulated fatigue damages of the bonding wires in each of the plurality of switches and the accumulated fatigue damages of the solder layers in each of the plurality of switches.

### Claim 2 (depends on 1)

The switching amplifier of claim 1, wherein the processing device is further configured to:
calculate a diode junction temperature for the bonding wire in each switch based at least in part on the power loss of each diode;
generate a second accumulated fatigue damage of the bonding wire in each switch based on the corresponding diode junction temperature; and
generate the estimated remaining lifetime of the switching amplifier based on at least one of the first accumulated fatigue damages of the bonding wires in each switch, the second accumulated fatigue damages of the bonding wires in each switch, and the accumulated fatigue damages of the solder layers in each switch.

### Claim 3 (depends on 2)

The switching amplifier of claim 2, wherein the processing device is further configured to:
generate the first accumulated fatigue damage of the bonding wire in each switch based on peak values and valley values of the switch junction temperature;
generate the second accumulated fatigue damage of the bonding wire in each switch based on peak values and valley values of the corresponding diode junction temperature; and
generate the accumulated damage of the solder layer in each switch based on peak values and valley values of the case temperature.

### Claim 4 (depends on 2)

The switching amplifier of claim 2, wherein the estimated remaining lifetime of the switching amplifier is generated based on a maximum value of the first accumulated fatigue damages of the bonding wires in each switch, the second accumulated fatigue damages of the bonding wires in each switch, and the accumulated fatigue damages of solder layers in each switch.

### Claim 5 (depends on 1)

The switching amplifier of claim 1, wherein each of the plurality of switches are thermally coupled to a heatsink; wherein the processing device is further configured for using a thermal model of each switch with the heatsink to calculate the switch junction temperature, the power loss of each switch is functioned as a current source applied to the thermal model of each switch with the heatsink; and wherein the processing device is further configured for using a thermal model of each switch with the corresponding diode and the heatsink to calculate the case temperature, the average value of the power loss of each switch and the power loss of the corresponding diode is functioned as a current source applied to the thermal model of each switch with the corresponding diode and the heatsink.

### Claim 6 (depends on 2)

The switching amplifier of claim 2, wherein each of the plurality of switches are thermally coupled to a heatsink; and wherein the processing device is further configured for using a thermal mode of each diode with the heatsink to calculate the diode junction temperature, the power loss of each diode is functioned as a current source applied to the thermal model of the diode with the heatsink.

### Claim 7 (depends on 1)

The switching amplifier of claim 1, wherein the power loss of each switch is calculated based on a duty cycle of the switch, a switching frequency command, and a reference current command; and wherein the power loss of each diode is calculated based on a duty cycle of the diode, the switching frequency command, and the reference current command.

### Claim 8

A method for estimating a remaining lifetime of a switching amplifier that comprises a power device, the power device configured for powering a load and comprised of a plurality of switches, wherein each of the plurality of switches is coupled in parallel with a diode; the method comprising:
calculating a switch junction temperature for a bonding wire in each switch based at least in part on a power loss of the switch;
generating a first accumulated fatigue damage of the bonding wire in each switch based on the switch junction temperature;
calculating a case temperature for a solder layer in each of the plurality of switches based on an average value of the power loss of each switch and a power loss of the corresponding diode;
generating an accumulated fatigue damage of the solder layer in each switch based on the case temperature; and
generating an estimated remaining lifetime of the switching amplifier based on at least one of the first accumulated fatigue damages of the bonding wires in each switch and the accumulated fatigue damages of the solder layers in each switch.

### Claim 9 (depends on 8)

The method of claim 8, further comprising:
calculating a diode junction temperature for the bonding wire in the corresponding switch based at least in part on the power loss of each diode;
generating a second accumulated fatigue damage of the bonding wire in each switch based on the corresponding diode junction temperature;
generating the estimated remaining lifetime of the switching amplifier based on at least one of the first accumulated fatigue damages of the bonding wires in each switch, the second accumulated fatigue damages of the bonding wires in each switch, and the accumulated fatigue damages of the solder layers in each switch.

### Claim 10 (depends on 9)

The method of claim 9, further comprising:
generating the first accumulated fatigue damage of the bonding wire in each switch based on peak values and valley values of the switch junction temperature;
generating the second accumulated fatigue damage of the bonding wire in each switch based on peak values and valley values of the corresponding diode junction temperature; and
generating the accumulated damage of the solder layer in each switch based on peak values and valley values of the case temperature.

### Claim 11

A gradient amplifier, comprising:
a power device comprising a plurality of bridge circuits coupled in series between two terminals of a gradient coil and each comprised of a plurality of switches; and a processing device configured to:
calculate a switch junction temperature for a bonding wire in each of the plurality of switches based at least in part on a power loss of each switch;
generate a first accumulated fatigue damage of the bonding wire in each switch based on the switch junction temperature; and
generate an estimated remaining lifetime of the switching amplifier based on the first accumulated fatigue damages of the bonding wires in each switch.

### Claim 12 (depends on 11)

The gradient amplifier of claim 11, wherein each of the plurality of switches is coupled in parallel with a diode, the processing device is further configured to:
calculate a diode junction temperature for the bonding wire in the corresponding switch based at least in part on the power loss of each diode;
generate a second accumulated fatigue damage of the bonding wire in each switch based on the corresponding diode junction temperature;
calculate a case temperature for a solder layer in each switch based on an average value of the power loss of each switch and a power loss of the corresponding diode;
generate an accumulated fatigue damage of the solder layer in each switch based on the case temperature; and
generate the estimated remaining lifetime of the switching amplifier based on at least one of the first accumulated fatigue damages of the bonding wires in each switch, the second accumulated fatigue damages of the bonding wires in each switch, and the accumulated fatigue damages of the solder layers in each switch.