# US 2021/0344274 A1 · Electric machine control

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2021/0344274 A1
- Document ID: US20210344274A1
- Status: Published application
- Kind: A1
- Application number: 17/285,962
- Filed: 2019-10-22
- Published: 2021-11-04
- Earliest claimed: 2018-10-25
- Assignees: Safran Electrical & Power
- Applicants: Safran Electrical & Power
- Inventors: Andrew Bloor
- Web page: https://patentgrep.com/patent/US20210344274A1

## CPC

- H02P 9/302: {Brushless excitation}
- H01F 38/18: Rotary transformers
- H02M 3/01: {Resonant DC/DC converters}
- H02M 3/33573: {Full-bridge at primary side of an isolation transformer}
- H02M 7/4818: {with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuits}
- H02P 9/08: Control of generator circuit during starting or stopping of driving means, e.g. for initiating excitation
- H02P 9/42: to obtain desired frequency without varying speed of the generator
- H02P 27/085: {wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency}
- H02M 7/4815: {Resonant converters (H02M7/4811 and H02M7/4826 take precedence)}
- H02P 2101/30: for aircraft
- Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- 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)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

Controlling a DC-AC inverter of an electric machine, where the electric machine comprises a resonant main exciter having rotary transformer. A voltage level of DC power received at a DC-AC inverter is monitored and the frequency of AC power generated by the DC-AC inverter and supplied to the rotary transformer is controlled based at least in part on the voltage level of the DC power.

## Claims

### Claim 1

A method of controlling a DC-AC inverter of an electric machine, wherein the electric machine comprises a resonant main exciter having a rotary transformer, the method comprising:
monitoring a voltage level of DC power received at the DC-AC inverter; and
controlling a characteristic of AC power generated by the DC-AC inverter and supplied to the rotary transformer, wherein controlling the characteristic of the AC power is based at least in part on the voltage level of the DC power, wherein the characteristic of the AC power comprises a frequency of the AC power.

### Claim 2 (depends on 1)

The method of claim 1, wherein controlling the characteristic of the AC power comprises changing the frequency of the AC power generated by the DC-AC inverter relative to a resonant frequency of the resonant main exciter based on a detected change in the DC power received by the DC-AC inverter.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
changing the frequency of the AC power to be closer to the resonant frequency of the resonant main exciter when a reduction in the voltage level of the DC power is detected; and/or
changing the frequency of the AC power to be further from the resonant frequency of the resonant main exciter when an increase in voltage level of the DC power is detected.

### Claim 4 (depends on 1)

The method of claim 1, wherein the characteristic of the AC power generated by the DC-AC inverter further comprises a phase of the AC power relative to a rotation of the rotary transformer.

### Claim 5 (depends on 4)

The method of claim 4, wherein controlling the characteristic of the AC power comprises changing the phase of the AC power relative to the rotation of the rotary transformer based on a detected change in the DC power received by the DC-AC inverter.

### Claim 6 (depends on 1)

The method of claim 1, further comprising controlling a characteristic of the AC power in order to reduce ripples in the amplitude of the AC power.

### Claim 7 (depends on 1)

The method of claim 1, further comprising:
receiving a feedback signal indicative of a generated output voltage of the electric machine when the electric machine is operating as a generator; wherein
controlling the characteristic of the AC power generated by the DC-AC inverter is further based at least in part on the feedback signal.

### Claim 8 (depends on 7)

The method of claim 7, wherein controlling the characteristic of the AC power comprises changing the frequency of the AC power generated by the DC-AC inverter relative to a resonant frequency of the resonant main exciter based at least in part on the generated output voltage of the electric machine and a desired generated output voltage of the electric machine.

### Claim 9 (depends on 7)

The method of claim 7, further comprising:
changing the frequency of the AC power to be closer to a resonant frequency of the resonant main exciter to increase the generated output voltage of the electric machine; and/or
changing the frequency of the AC power to be further from the resonant frequency of the rotary transformer to decrease the generated output voltage of the electric machine.

### Claim 10 (depends on 7)

The method of claim 7, further comprising controlling the characteristic of the AC power in order to achieve a desired generated output voltage of the electric machine when the electric machine is operating as the generator.

### Claim 11 (depends on 1)

The method of claim 1, wherein the DC-AC inverter comprises a plurality of switching devices configured to convert the received DC power to AC power, the method further comprising:
controlling a timing of switching of the plurality of switching devices in order to control the characteristic of the AC power generated by the DC-AC inverter.

### Claim 12 (depends on 1)

A computer program configured to perform the method of claim 1 when executed on one or more processors.

### Claim 13

A control unit for controlling a DC-AC inverter of an electric machine, wherein the electric machine comprises a resonant main exciter having a rotary transformer, and wherein the DC-AC inverter is configured to receive DC power, convert the received DC power to AC power, and supply the AC power to the rotary transformer, and wherein the control unit is configured to:
monitor a voltage level of the DC power received by the DC-AC inverter; and
control a characteristic of the AC power generated by the DC-AC inverter based at least in part on the voltage level of the DC power, wherein the characteristic of the AC power comprises a frequency of the AC power.

### Claim 14

An electric machine comprising:
a resonant main exciter comprising a rotary transformer;
a DC-AC inverter configured to:
receive DC power;
convert the received DC power to AC power; and
supply the AC power to the rotary transformer; and
a control unit for controlling the DC-AC inverter, wherein the control unit is configured to:
monitor a voltage level of the DC power received by the DC-AC inverter; and
control a characteristic of the AC power generated by the DC-AC inverter based at least in part on the voltage level of the DC power, wherein the characteristic of the AC power comprises a frequency of the AC power, and wherein the control unit is coupled to the DC-AC inverter and is configured to adjust a gain of the electric machine by controlling a characteristic of the AC power generated by the DC-AC inverter.

### Claim 15 (depends on 14)

An aircraft engine comprising the electric machine of claim 14.

### Claim 16 (depends on 15)

An aircraft comprising the aircraft engine of claim 15.