# US 9,882,515 B2 · Method for making a motor quieter

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

- Number: US 9,882,515 B2
- Document ID: US9882515B2
- Status: Granted
- Kind: B2
- Application number: 15/626,205
- Filed: 2017-06-19
- Published: 2017-10-05
- Granted: 2018-01-30
- Earliest claimed: 2013-08-23
- Assignees: LD Design Electronics AB
- Applicants: LD Design Electronics AB
- Inventors: Lars Dernebo
- Web page: https://patentgrep.com/patent/US9882515B2

## CPC

- H02P 6/153: {wherein the commutation is advanced from position signals phase in function of the speed}
- F04D 27/004: {by varying driving speed}
- F04D 29/663: {Sound attenuation}
- H02P 6/22: in a selected direction of rotation
- Y02B 30/70: Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

The method is for making an electric motor more efficient by iteratively changing when a processor sends activation signals to transistors to minimize a current required to rotate a rotor at a constant rotational speed. The method is also for changing a rotational direction of the rotor by switching the order in which activation signals are sent to the transistors.

## Claims

### Claim 1

A method for making an electric motor more efficient, comprising:
providing an electric motor having a rotor being rotatable in a first direction relative to a stator winding, a first and a second transistor electrically connected to the stator winding and to a processor, the rotor having magnets of first and second polarities separated at polarity changing points;
a sensor sensing a first polarity changing point, the sensor sending a first triggering signal to the processor;
upon receipt of the first triggering signal, the processor delaying by a time period (t1) before sending a first activation signal to the first transistor to start rotating the rotor in the first direction, the first activation signal lasting for a time period (I1);
the processor measuring a current A1 driving the electric motor at a rotational speed;
the sensor sensing a second polarity changing point, the sensor sending a second triggering signal to the processor;
upon receipt of the second triggering signal, the processor delaying by a time period (t1′) before sending a second activation signal to the second transistor to continue rotating the rotor in the first direction, the second activation signal lasting for a time period (I2);
the processor measuring a current A2 driving the electric motor at the rotational speed;
the processor comparing the current A1 to the current A2 and selecting time period (t1) for sending activation signals when the current A2 is greater than the current A1 and selecting time period (t1′) for sending activation signals when the current A1 is greater than the current A2; and
the processor iteratively changing the time period (t1) for each activation signal sent until a minimum current Amin is found by comparing measured currents to optimize an efficiency of the electric motor.

### Claim 2 (depends on 1)

The method according to claim 1 wherein the method further comprises using a first PWM pulse as the first activation signal.

### Claim 3 (depends on 1)

The method according to claim 1 wherein the method further comprises varying a length of the first PWM pulse to the first transistor.

### Claim 4 (depends on 1)

The method according to claim 1 wherein the method further comprises measuring the current A1 and the current A2 at a constant rotational speed (ω) of the rotor.

### Claim 5 (depends on 1)

The method according to claim 1 wherein the method further comprises the processor continuously monitoring currents driving the electric motor.

### Claim 6 (depends on 1)

The method according to claim 1 wherein the method further comprises alternatingly using the first and second transistor to drive the rotor in the first rotational direction.