Input vector set for position detection of PM motors
A method of determining angular position (A) of a rotor of an N-phase permanent magnet motor (PMM). A processor having an associated stored angular position determination (APD) algorithm is programmed to implement the algorithm to cause an associated motor controller to execute steps including forcing one vector at a time a phase vector set of current or voltage vectors to stator terminals of windings for the N-phases a positive and negative magnitude vector, wherein the vector magnitude is sufficiently small to not move the rotor, and a time duration for the forcing current or voltage vectors is essentially constant. The resulting stator current or voltage levels are measured for each current or voltage vector. An N-dimension current vector or voltage vector is generated from superposition of the resulting stator current levels or resulting stator voltage levels. The N-dimension current vector or voltage vector is used to determine angular position.
1. A method of determining an angular position (A) of a rotor of an N-phase permanent magnet motor (PMM), comprising:
providing a processor having an associated memory storing an angular position determination (APD) algorithm, wherein said processor is programmed to implement said APD algorithm to cause an associated motor controller to execute:
forcing one vector at a time a phase vector set of current vectors or voltage vectors to stator terminals of stator windings for said N-phases of said PMM including a positive magnitude vector and a negative magnitude vector, wherein a magnitude of said current vectors or said voltage vectors are all sufficiently small to not move said rotor, and wherein a time duration for said forcing said current vectors or said voltage vectors is essentially constant;
measuring resulting stator current or voltage levels for each said current vectors or said voltage vectors;
generating an N-dimension current vector or voltage vector from superposition of said resulting stator current levels or said resulting stator voltage levels, and
using said N-dimension current vector or voltage vector, determining said angular position.
2. The method of claim 1 , wherein said phase vector set of current vectors or voltage vectors are all fundamental vectors.
3. The method of claim 1 , wherein said stator terminals are coupled into a controller loop that includes said processor.
4. The method of claim 1 , wherein said forcing comprises forcing said current vectors and said sensing comprises sensing said resulting stator voltage levels.
5. The method of claim 1 , wherein said forcing comprises forcing said voltage vectors and said sensing comprises sensing said resulting stator current.
6. The method of claim 5 , wherein said using comprises utilizing an angular position determination equation given by:
θ
=
tan
-
1
(
-
∑
n
=
1
N
x
n
·
sin
(
2
π
·
(
n
-
1
)
N
)
∑
n
=
1
N
x
n
·
cos
(
2
π
·
(
n
-
1
)
N
)
)
wherein said x n are said resulting stator current or said resulting stator voltage levels.
7. The method of claim 1 , wherein said generating said N-dimension current vector or voltage vector further comprises for each of said N-dimensions determining a largest absolute value of a difference between said resulting stator current or said resulting stator voltage levels from said positive magnitude vector and said negative magnitude vector.
8. The method of claim 1 , further comprising a tuning process for adjusting said magnitude and said time duration.
9. The method of claim 1 , wherein said processor and said associated memory are both provided on a microcontroller unit (MCU) chip.
10. The method of claim 1 , wherein said motor controller implements field-oriented control (FOC).
11. The method of claim 1 , wherein said forcing comprises using different ones of said phase vector sets, and performing mathematics to determine said resulting stator current or voltage levels.
12. The method of claim 1 , further comprising repeating said forcing a plurality of times, and then averaging said resulting stator current or voltage levels.
13. The method of claim 1 , further comprising averaging said resulting stator current or voltage levels.
14. A microcontroller unit (MCU) chip, comprising:
a substrate having the following formed in or thereon configured to realize a motor controller for controlling an N-phase permanent magnet motor (PMM) including a rotor, including:
at least one analog-to-digital converter (ADC) for receiving resulting N-phase measurements from current measurement circuits or voltage measurement circuits coupled to stator windings of said PMM associated with each of said N-phases;
a pulse-width modulation (PWM) driver;
a first non-volatile program memory including an angular position determination (APD) algorithm including a signal generator algorithm for controlling an amplitude and duration of an input vector set and an angular position (A) determination algorithm stored therein;
an ID controller for controlling direct (d) current and an IQ controller for controlling quadrature (q) current;
a digital I/O (interface);
a central processing unit (CPU) coupled through said digital I/O (interface) to receive said N-phase measurements after processing by said ADC's;
a clock, and
a digital data bus and an address bus for coupling together said ADC, said first non-volatile program memory, said digital I/O (interface), said CPU, and said clock,
said signal generator algorithm providing signals used by said PWM driver for generating a voltage input vector set of current vectors or voltage vectors forced one vector at a time to stator terminals of stator windings for said N-phases of said PMM including a positive magnitude vector and a negative magnitude vector, wherein a magnitude of said current vectors or said voltage vectors are all sufficiently small to not move said rotor, and wherein a time duration for said forcing said current vectors or said voltage vectors is essentially constant;
said CPU generating an N-dimension current vector or voltage vector from superposition of selected ones of said N-phase measurements, and
said APD algorithm using said N-dimension current vector or voltage vector for determining said angular position.
15. The MCU chip of claim 14 , wherein said vector set of current vectors or voltage vectors are all fundamental vectors.
16. The MCU chip of claim 14 , wherein said wherein said forcing comprises forcing said current vectors and said sensing comprises sensing said resulting stator voltage.
17. The MCU chip of claim 14 , wherein said forcing comprises forcing said voltage vectors and said sensing comprises sensing said resulting stator current.
18. The MCU chip of claim 14 , wherein said using comprises utilizing an angular position determination equation given by:
θ
=
tan
-
1
(
-
∑
n
=
1
N
x
n
·
sin
(
2
π
·
(
n
-
1
)
N
)
∑
n
=
1
N
x
n
·
cos
(
2
π
·
(
n
-
1
)
N
)
)
wherein said x n are said resulting stator current or said resulting stator voltage levels.
19. The MCU chip of claim 14 , wherein said selected ones of said N-phase measurements is identified for each of said N-phase measurements by determining a largest absolute value of a difference between resulting stator current or resulting stator voltage levels from said positive magnitude vector and said negative magnitude vector.
20. The MCU chip of claim 14 , wherein said motor controller implements field-oriented control (FOC).