# US 10,873,284 B2 · Motor control unit and electric power steering apparatus equipped with the same

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- Number: US 10,873,284 B2
- Document ID: US10873284B2
- Status: Granted
- Kind: B2
- Application number: 16/613,831
- Filed: 2018-06-12
- Published: 2020-06-11
- Granted: 2020-12-22
- Earliest claimed: 2017-06-16
- Assignees: Nsk Ltd.
- Applicants: NSK Ltd.
- Inventors: Hiroaki Takase; Ryo Minaki; Hideki Sawada; Takayoshi Sugawara
- Web page: https://patentgrep.com/patent/US10873284B2

## CPC

- B62D 5/046: {Controlling the motor}
- H02P 21/16: Estimation of constants, e.g. the rotor time constant
- H02M 1/0025: {Arrangements for modifying reference values, feedback values or error values in the control loop of a converter}
- H02M 1/385: {with means for correcting output voltage deviations introduced by the dead time}
- H02M 7/53873: {with digital control}
- H02P 21/22: Current control, e.g. using a current control loop
- H02P 27/08: with pulse width modulation
- H02M 1/0009: {Devices or circuits for detecting current in a converter}
- H02M 1/32: Means for protecting converters other than automatic disconnection
- B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M)
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- 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)

## Abstract

A vector-control type motor control unit that calculates dq-axes control assist command values, calculates dq-axes current command values from the dq-axes control assist command values, converts the dq-axes current command values into 3-phase duty command values, and drives and controls a 3-phase brushless motor by an inverter of a PWM control, wherein a dead time compensation of the inverter is performed by calculating 3-phase dead time reference compensation values based on a motor rotational angle which is phase-corrected by using the dq-axes current command values, calculating dead time compensation values by processing the 3-phase dead time reference compensation values by a gain and a sign, and adding the dead time compensation values to dq-axes voltage command values or 3-phase voltage command values.

## Claims

### Claim 1

A vector-control type motor control unit that calculates dq-axes control assist command values, calculates dq-axes current command values from said dq-axes control assist command values, converts said dq-axes current command values into 3-phase duty command values, and drives and controls a 3-phase brushless motor by an inverter of a pulse width modulation (PWM) control, comprising:
a central processing unit (CPU) which comprises:
an axes current factor phase-correction calculating section to calculate a phase-correction rotational angle by phase-correcting a motor rotational angle using said dq-axes current command values;
an angle-dead time compensation value functional section to calculate 3-phase dead time reference compensation values based on said phase-correction rotational angle;
an inverter applying voltage sensitive-gain calculating section to calculate a voltage sensitive gain based on an inverter applying voltage; and
a dead time compensation-value outputting section to output dq-axes dead time compensation values which are obtained by multiplying said 3-phase dead time reference compensation values by said voltage sensitive gain and performing 3-phase/dq-axes conversion to said multiplied results,
wherein a dead time compensation of said inverter is performed by using said dq-axes dead time compensation values and dq-axes voltage command values obtained by processing said dq-axes current command values.

### Claim 2 (depends on 1)

The vector-control type motor control unit according to claim 1,
wherein said dead time compensation-value outputting section comprises:
multiplying sections to multiply said 3-phase dead time reference compensation values by said voltage sensitive gain; and
a 3-phase alternating current (AC)/dq-axes converting section to convert 3-phase outputs of said multiplying sections into said dq-axes dead time compensation values.

### Claim 3 (depends on 1)

The vector-control type motor control unit according to claim 1, further comprising:
a current command value sensitive-gain calculating section to calculate a current command value sensitive gain which makes a compensation amount of said dq-axes dead time compensation values be variable depending on said control assist command values.

### Claim 4 (depends on 1)

The vector-control type motor control unit according to claim 1,
wherein said axes current factor phase-correction calculating section comprises:
a dq-axes current ratio calculating section to calculate a current ratio of said dq-axes current command values; and
a variation angle calculating section to calculate a variation angle based on said current ratio,
wherein said motor rotational angle is phase-corrected by using said variation angle.

### Claim 5 (depends on 1)

An electric power steering apparatus that is equipped with the vector-control type motor control unit according to claim 1, and applies an assist torque to a steering system of a vehicle.

### Claim 6

A vector-control type motor control unit that calculates dq-axes control assist command values, calculates dq-axes current command values from said dq-axes control assist command values, converts said dq-axes current command values into dq-axes voltage command values, converts said dq-axes voltage command values into 3-phase duty command values, and drives and controls a 3-phase brushless motor by an inverter of a pulse width modulation (PWM) control, comprising:
a central processing unit (CPU) which comprises:
a space vector modulating section to obtain 3-phase voltage command values by performing a space vector modulation to said dq-axes voltage command values;
an axes current factor phase-correction calculating section to calculate a phase-correction rotational angle by phase-correcting a motor rotational angle using said dq-axes current command values;
an angle-dead time compensation value functional section to calculate 3-phase dead time reference compensation values based on said phase-correction rotational angle;
an inverter applying voltage sensitive-gain calculating section to calculate a voltage sensitive gain based on an inverter applying voltage;
a dead time compensation-value outputting section to output first 3-phase dead time compensation values obtained by multiplying said 3-phase dead time reference compensation values by said voltage sensitive gain; and
a current command value sensitive-gain calculating section to calculate a current command value sensitive gain which makes a compensation amount of said first 3-phase dead time compensation values be variable depending on said control assist command values,
wherein a dead time compensation of said inverter is performed by calculating second 3-phase dead time compensation values by multiplying said first 3-phase dead time compensation values by said current command value sensitive gain, and adding said second 3-phase dead time compensation values to said 3-phase voltage command values.

### Claim 7 (depends on 6)

The vector-control type motor control unit according to claim 6, further comprising:
a current control delay model to input said control assist command values and compensate a current delay;
said current command value sensitive-gain calculating section outputs said current command value sensitive gain based on an output of said current control delay model; and
a multiplying section to multiply said current command value sensitive gain by a sign,
wherein said compensation sign estimating section estimates said sign of an output of said current control delay model.

### Claim 8 (depends on 6)

The vector-control type motor control unit according to claim 6,
wherein said axes current factor phase-correction calculating section comprises:
a dq-axes current ratio calculating section to calculate a current ratio of said dq-axes current command values; and
a variation angle calculating section to calculate a variation angle based on said current ratio,
wherein said motor rotational angle is phase-corrected by using said variation angle.

### Claim 9 (depends on 6)

An electric power steering apparatus that is equipped with the vector-control type motor control unit according to claim 6, and applies an assist torque to a steering system of a vehicle.