# US 12,191,758 B2 · System and method for operating a three-phase inverter with four or more legs

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- Number: US 12,191,758 B2
- Document ID: US12191758B2
- Status: Granted
- Kind: B2
- Application number: 18/026,427
- Filed: 2021-09-08
- Published: 2023-11-30
- Granted: 2025-01-07
- Earliest claimed: 2020-09-18
- Assignees: Cummins Inc.
- Applicants: Cummins Inc.
- Inventors: Akm Arafat; Moinul S. Haque; Bradford K. Palmer; Patrick Kaufman
- Web page: https://patentgrep.com/patent/US12191758B2

## CPC

- H02M 1/325: {with means for allowing continuous operation despite a fault, i.e. fault tolerant converters}
- H02M 7/53876: {based on synthesising a desired voltage vector via the selection of appropriate fundamental voltage vectors, and corresponding dwelling times}
- B60L 50/60: using power supplied by batteries (in combination with fuel cells B60L50/75)
- H02M 1/327: {against abnormal temperatures}
- H02M 7/53871: {with automatic control of output voltage or current}
- H02P 21/22: Current control, e.g. using a current control loop
- B60K 6/40: characterised by the assembly or relative disposition of components
- B60L 2210/40: DC to AC converters
- B60Y 2200/92: Hybrid vehicles
- 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)
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60Y: INDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY

## Abstract

An inverter system is provided such that the system includes a direct-current (DC) voltage supply, an inverter, an electric machine such as a motor, and a controller coupled with the inverter. The inverter has four or more legs, each with two switches operating complementary to each other. The controller can determine which three of the four or more legs are selected to operate the inverter and uses a remaining one of the four or more legs to operate the inverter by activating/deactivating certain switches during null vector state.

## Claims

### Claim 1

An inverter system comprising:
a direct-current (DC) voltage supply;
an inverter electrically coupled with the DC voltage supply, the inverter comprising four or more legs, each leg including two switches operating complementary to each other;
an electric machine electrically coupled with the inverter; and
a controller coupled with the inverter and operative to determine which three of the four or more legs are selected to operate the inverter, the controller implementing a space vector pulse width modulation (SVPWM) strategy in which a remaining one of the four or more legs is connected to operate the inverter when a current switching state of the SVPWM strategy is in a first null vector state.

### Claim 2 (depends on 1)

The inverter system of claim 1, wherein one of the legs operating the inverter is disconnected from the inverter when the current switching state of the SVPWM strategy is in a second null vector state.

### Claim 3 (depends on 1)

The inverter system of claim 1, wherein the controller implements a master scheduler module in selecting the three of the four or more legs such that each of the four or more legs has substantially equal time operating the inverter.

### Claim 4 (depends on 1)

The inverter system of claim 1, further comprising at least one temperature sensor operatively coupled with the four or more legs, wherein the controller selects the three of the four or more legs by receiving junction temperature information of the four or more legs from the temperature sensor and determining to replace a leg of highest junction temperature with the remaining leg.

### Claim 5 (depends on 1)

The inverter system of claim 1, wherein the inverter comprises five legs.

### Claim 6 (depends on 1)

The inverter system of claim 1, further comprising a junction box disposed between the inverter and the electric machine, the junction box comprising a plurality of switches controlled by the controller to electrically couple the selected three of the four or more legs with the electric machine.

### Claim 7 (depends on 6)

The inverter system of claim 6, wherein the junction box further comprises a plurality of secondary switches controlled by the controller to electrically couple at least one of the legs with an external component.

### Claim 8 (depends on 7)

The inverter system of claim 7, wherein the external component is a braking resistor.

### Claim 9 (depends on 7)

The inverter system of claim 7, wherein the external component is a catalyst heater.

### Claim 10

A method of operating an inverter system comprising a direct-current (DC) voltage supply, an inverter electrically coupled with the DC voltage supply, the inverter comprising four or more legs, each leg including two switches operating complementary to each other, an electric machine electrically coupled with the inverter, and a controller coupled with the inverter, the method comprising:
determining, by the controller, which three of the four or more legs are to be selected to operate the inverter by implementing a space vector pulse width modulation (SVPWM) strategy; and
replacing, by the controller when a current switching state is in a first null vector state or a second null vector state, one of the selected three legs with the remaining leg.

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
selecting the three of the four or more legs to operate the inverter using a master scheduler module such that each of the four or more legs has substantially equal operation time.

### Claim 12 (depends on 10)

The method of claim 10, further comprising:
receiving, by the controller from at least one temperature sensor operatively coupled with the four or more legs, junction temperature information of the four or more legs; and
selecting, by the controller based on the junction temperature information, a leg of highest junction temperature among the four or more legs to be replaced with the remaining leg.

### Claim 13 (depends on 10)

The method of claim 10, further comprising:
activating, by the controller, at least one switch in a junction box disposed between the inverter and the electric machine when the current switching state is in the first null vector state, the junction box comprising a plurality of switches controlled by the controller to electrically couple the selected three of the four or more legs with the electric machine.

### Claim 14 (depends on 13)

The method of claim 13, further comprising:
deactivating, by the controller, at least one switch in the junction box when a current switching state is in the second null vector state.

### Claim 15

A vehicle comprising:
a direct-current (DC) battery;
an inverter electrically coupled with the DC battery, the inverter comprising four legs, each leg including two switches operating complementary to each other;
an electric motor electrically coupled with and powered by the inverter;
a controller coupled with the inverter and operative to determine which three of the four legs are selected to operate the inverter, the controller implementing a space vector pulse width modulation (SVPWM) strategy in which a remaining one of the four legs is connected to operate the inverter when a current switching state of the SVPWM strategy is in a first null vector state; and
a junction box disposed between the inverter and the electric motor, the junction box comprising a plurality of switches controlled by the controller to electrically couple the selected three of the four legs with the electric motor the junction box further comprising a plurality of secondary switches controlled by the controller to electrically couple at least one of the legs with an additional electric component.

### Claim 16 (depends on 15)

The vehicle of claim 15, wherein the additional electric component is a braking resistor.

### Claim 17 (depends on 15)

The vehicle of claim 15, further comprising an engine and an exhaust system coupled therewith, wherein the additional electric component is a catalyst heater operatively coupled with the exhaust system.

### Claim 18 (depends on 15)

The vehicle of claim 15, wherein one of the legs operating the inverter is disconnected from the inverter when the current switching state of the SVPWM strategy is in a second null vector state.

### Claim 19 (depends on 15)

The vehicle of claim 15, wherein the controller implements a master scheduler module in selecting the three of the four legs such that each of the four legs has substantially equal time operating the inverter.

### Claim 20 (depends on 15)

The vehicle of claim 15, further comprising at least one temperature sensor operatively coupled with the four legs, wherein the controller selects the three of the four legs by receiving junction temperature information of the four legs from the temperature sensor and determining to replace a leg of highest junction temperature with the remaining leg.