System and method for controlling high-torque, high speed electric motors

Patent metadata

Field	Value
Publication number	US-12170467-B2
Application number	US-202318199849-A
Country	US
Kind code	B2
Filing date	May 19, 2023
Priority date	May 19, 2022
Publication date	Dec 17, 2024
Grant date	Dec 17, 2024

Abstract

A method includes, at a controller: directing current through a set of coil assemblies in an electric motor based on a first commutation technique; in response to an operating speed of the electric motor exceeding a first operating speed threshold, initiating a transition from the first commutation technique to a second commutation technique; during a transition period, directing current through the set of coil assemblies based on the first commutation technique controlled according to a first pulse width modulation scheme and the second commutation technique controlled according to a second pulse width modulation scheme; and, in response to completion of the transition period, directing current through the set of coil assemblies based on the second commutation technique.

First claim

We claim:

1. A method comprising, at a motor controller:
during a first time period:
detecting a first operating speed of an electric motor comprising a set of coil assemblies;
detecting a torque demand of the electric motor;
estimating a first efficiency of a 120-degree commutation technique at the electric motor based on the first operating speed and the torque demand;
estimating a second efficiency of a 180-degree commutation technique at the electric motor based on the first operating speed and the torque demand;
setting a first operating speed threshold based on the first efficiency and the second efficiency;
in response to the first operating speed falling below the first operating speed threshold:
generating a first varying signal based on the 120-degree commutation technique; and
driving current through the set of coil assemblies according to the first varying signal;

detecting a second operating speed of the electric motor, the second operating speed exceeding the first operating speed; and
in response to the second operating speed exceeding the first operating speed threshold, initiating a first transition from the 120-degree commutation technique to the 180-degree commutation technique during a first transition period of a first transition duration;

during the first transition period:
generating a second varying signal based on a combination of:
the 120-degree commutation technique transitioning from a first duty rate to a second duty rate; and
the 180-degree commutation technique transitioning from the second duty rate to the first duty rate;

driving current through the set of coil assemblies according to the second varying signal; and

during a second time period succeeding the first time period, in response to completion of the first transition period:
generating a third varying signal based on the 180-degree commutation technique; and
driving current through the set of coil assemblies according to the third varying signal.

2. The method of claim 1 :
further comprising, at the motor controller, accessing a first configuration corresponding to the first transition and defining:
the first operating speed threshold;
the first transition duration; and
a function defining a relationship between a first duty cycle of the 120-degree commutation technique and a second duty cycle of the 180-degree commutation technique during the first transition duration; and

wherein driving current through the set of coil assemblies according to the second varying signal comprises driving current through the set of coil assemblies based on:
pulse-width-modulating the 120-degree commutation technique according to the first duty cycle decreasing during the first transition duration according to the function; and
pulse-width-modulating the 180-degree commutation technique according to the second duty cycle increasing during the first transition duration according to the function.

3. The method of claim 2 :
wherein accessing the first configuration comprises accessing the first configuration defining the function comprising a linear function defining an inverse linear relationship between the first duty cycle of the 120-degree commutation technique and the second duty cycle of the 180-degree commutation technique during the first transition duration.

4. The method of claim 1 , further comprising, during the first time period, at the motor controller:
accessing a first lookup table, the first lookup table correlating a set of throttle positions with a set of transition durations comprising the first transition duration;
detecting a first throttle position; and
selecting the first transition duration from the first lookup table based on the first throttle position.

5. The method of claim 1 :
further comprising, at the motor controller:
detecting a first ambient air temperature; and
setting the first transition duration proportional to the first ambient air temperature.

6. The method of claim 1 :
further comprising, during the first time period;
detecting a first state of charge of a power source electrically coupled to the motor controller;

wherein setting the first operating speed threshold comprises setting the first operating speed threshold based on the first state of charge;
further comprising, during a third time period succeeding the first time period:
detecting a second state of charge of the source;
in response to the second state of charge falling below the charge threshold, setting a second operating speed threshold falling below the first operating speed threshold;
driving current through the set of coil assemblies based on the 120-degree commutation technique; and
in response to a third operating speed of the electric motor exceeding the second operating speed threshold, initiating a second transition characterized by the second varying signal and a second transition period;

during the second transition period, driving current, from the source, through the set of coil assemblies based on:
the 120-degree commutation technique; and
the 180-degree commutation technique; and

in response to completion of the second transition period, driving current, from the source, through the set of coil assemblies based on the 180-degree commutation technique.

7. The method of claim 1 , wherein driving current through the set of coil assemblies according to the first varying signal comprises driving current through the set of coil assemblies according to the first varying signal to generate a toroidal magnetic field tunnel configured to sequentially and magnetically couple a set of magnetic elements in the electric motor.

8. The method of claim 1 , wherein driving current through the set of coil assemblies according to the second varying signal comprises driving current through the set of coil assemblies based on:
the 120-degree commutation technique:
comprising a six-step commutation technique; and
controlled according to a first pulse width modulation scheme; and

the 180-degree commutation technique:
comprising a 180-degree field-oriented control commutation technique; and
controlled according to a second pulse width modulation scheme.

9. The method of claim 1 , further comprising:
during a third time period preceding the first time period:
accessing a corpus of historical utilization data associated with a first user during a first interval, the corpus of historical data comprising:
throttle position data;
operating speed data;
torque demand data; and
state of charge data;

extracting a first set of features characterizing utilization by the first user based on the corpus of historical utilization data;
classifying the first user into a first user type, in a set of user types, based on the first set of features and a model correlating features characteristic of utilization with the set of user types; and
generating a first user profile defining a first configuration based on the first user type, the first user profile defining;
a first operating speed threshold value; and
a first transition duration value; and

during the first time period:
in response to receiving selection of the first user profile:
assigning the first operating speed threshold value to the first operating speed threshold; and
assigning the first transition duration value to the first transition duration.

10. The method of claim 1 , wherein generating the second varying signal comprises generating the second varying signal by combining:
a first signal component, generated according to the 120-degree communication techniques, pulse-width-modulated from 100% duty to 0% duty over the first transition duration; and
a second signal component, gener

Assignees

• Linear Labs Inc

Inventors

• Kopf Carlo
• Hatch Erik

Classifications

• H02K1/182

  to stators axially facing the rotor, i.e. with axial or conical air gap · CPC title

• H02K1/2798

  where both axial sides of the stator face a rotor · CPC title

• H02P6/153 Primary

  wherein the commutation is advanced from position signals phase in function of the speed · CPC title

• H02P6/08

  Arrangements for controlling the speed or torque of a single motor (H02P6/10, H02P6/28 take precedence) · CPC title

• H02K16/02 Primary

  Machines with one stator and two {or more} rotors · CPC title