Rotor position sensing system for permanent magnet synchronous motors and related methods
Implementations of a system for sensing rotor position of a PMSM may include: a controller which may be coupled with the PMSM. The controller may be configured to apply a plurality of voltage vectors to the PMSM to generate a plurality of sensing signals from a stator of the PMSM in response. A comparator may be coupled to the PMSM configured to receive and to compare each one of the plurality of sensing signals with a threshold voltage. A rise time measurement circuit may calculate a plurality of rise times using the plurality of sensing signals in response to receiving a signal from the comparator. The rotor-angle estimation circuit may be configured to identify from the plurality of rise times a shortest rise time and a voltage vector corresponding with the shortest rise time and thereby identify the position of the rotor of the PMSM.
1. A system for sensing rotor position of a permanent magnet synchronous motor, comprising:
a controller configured to couple with a permanent magnet synchronous motor (PMSM), wherein the controller is configured to apply a plurality of voltage vectors to the PMSM to generate a plurality of sensing signals from a stator of the PMSM in response;
an analog to digital (A/D) converter configured to couple to the PMSM, wherein the A/D converter is configured to convert the plurality of sensing signals into a plurality of digital current signals;
a rise time measurement circuit configured to couple to the PMSM, wherein the rise time measurement circuit is configured to calculate a plurality of rise times using at least the plurality of digital current signals, a first threshold current and a second threshold current;
a memory coupled with the rise time measurement circuit, wherein the memory is configured to store the plurality of rise times; and
a rotor-angle estimation circuit coupled with the memory, wherein the rotor-angle estimation circuit is configured to calculate a rotor position relative to the stator of the PMSM using the plurality of rise times;
wherein the controller is configured to generate the first threshold current and the second threshold current.
2. The system of claim 1 , further comprising an amplifier coupled to a resistor, wherein the amplifier is configured to receive and to amplify the plurality of sensing signals to form a plurality of amplified sensing signals.
3. The system of claim 1 , wherein the first threshold current and the second threshold current are related by an equation
I
th
1
=
4
3
I
th
2
where I th1 is the first threshold current and I th2 is the second threshold current.
4. The system of claim 1 , wherein the plurality of voltage vectors is 12 voltage vectors.
5. The system of claim 1 , wherein the plurality of voltage vectors is 24 voltage vectors.
6. The system of claim 1 , wherein the controller is configured to generate a first A/D threshold value and a second A/D threshold value using one of a first A/D threshold value equation and a second A/D threshold value equation; wherein the first A/D threshold value equation is
A
D
th
1
=
V
th
1
(
2
n
Vref
A
D
)
and the second A/D threshold value equation is
A
D
th
2
=
V
th
2
(
2
n
Vref
A
D
)
where AD th i is the first A/D threshold value, AD th2 is the second A/D threshold value, V th i is a first threshold voltage, Vt h2 is a second threshold voltage, n is an A/D resolution, and Vre f AD is a full scale voltage value.
7. The system of claim 6 , wherein a rise time measurement circuit measures each rise time using a rise time measurement equation;
wherein the rise time measurement equation is
T
r
=
(
A
D
th
-
A
D
1
A
D
2
-
A
D
1
)
(
t
2
-
t
1
)
+
t
1
where T r is the rise time, AD th is one of the first A/D value threshold and the second A/D value threshold, AD 2 is a first value from the A/D converter formed when AD 2 exceeds AD th , AD 1 is a second value from the A/D converter formed prior to AD 2 exceeding AD th , t 2 is a time corresponding with AD 2 , and t 1 is a time corresponding with AD 1 .
8. A system for sensing rotor position of a permanent magnet synchronous motor, comprising:
a controller configured to couple with a permanent magnet synchronous motor (PMSM), wherein the controller is configured to apply a plurality of voltage vectors to the PMSM to generate a plurality of sensing signals from a stator of the PMSM in response;
an analog to digital (A/D) converter configured to couple to the PMSM, wherein the A/D converter is configured to convert the plurality of sensing signals into a plurality of digital current signals;
a rise time measurement circuit configured to couple to the PMSM, wherein the rise time measurement circuit is configured to calculate a plurality of rise times using the plurality of digital current signals and one or more threshold currents;
a memory coupled with the rise time measurement circuit, wherein the memory is configured to store the plurality of rise times; and
a rotor-angle estimation circuit coupled with the memory, wherein the rotor-angle estimation circuit is configured to calculate a rotor position relative to the stator of the PMSM using the plurality of rise times;
wherein the controller is configured to generate the one or more threshold currents.
9. System of claim 8 , further comprising an amplifier configured to receive and to amplify the plurality of sensing voltage signals to form a plurality of amplified sensing voltage signals.
10. The system of claim 8 , wherein the one or more threshold currents comprise a first threshold current and a second threshold current, wherein the first threshold current and the second threshold current are related by an equation
I
th
1
=
4
3
I
th
2
where I th1 is the first threshold current and I th2 is the second threshold current.
11. The system of claim 8 , wherein the plurality of voltage vectors is 12 voltage vectors.
12. The system of claim 8 , wherein the plurality of voltage vectors is 24 voltage vectors.
13. The system of claim 8 , wherein the controller is configured to generate a first A/D threshold value and a second A/D threshold value using one of a first A/D threshold value equation and a second A/D threshold value equation;
wherein the first A/D threshold value equation is
A
D
th
1
=
V
th
1
(
2
n
Vref
A
D
)
and the second A/D threshold value equation is
A
D
th
2
=
V
th
2
(
2
n
Vref
A
D
)
where AD th1 is the first A/D threshold value, AD th2 is the second A/D threshold value, V th1 is a first threshold voltage, V th2 is a second threshold voltage, n is an A/D resolution, and Vref AD is a full scale voltage value.
14. The system of claim 13 , wherein a rise time measurement circuit measures each rise time using a rise time measurement equation;
wherein the rise time measurement equation is
T
r
=
(
A
D
th
-
A
D
1
A
D
2
-
A
D
1
)
(
t
2
-
t
1
)
+
t
1
where T r is the rise time, AD th is one of the first A/D value threshold and the second A/D value threshold, AD 2 is a first value from the A/D converter formed when AD 2 exceeds AD th , AD 1 is a second value from the A/D converter formed prior to AD 2 exceeding AD th , t 2 is a time corresponding with AD 2 , and t 1 is a time corresponding with AD 1 .
15. A system for sensing rotor position of a permanent magnet synchronous motor, comprising:
a controller configured to couple with a permanent magnet synchronous motor (PMSM), wherein the controller is configured to apply a plurality of voltage vectors to the PMSM to generate a plurality of sensing signals from a stator of the PMSM in response;
an analog to digital (A/D) converter configured to couple to the PMSM, wherein the A/D converter is configured to convert the plurality of sensing signals into a plurality of digital current signals;
a rise time measurement circuit configured to couple to the PMSM, wherein the rise time measurement circuit is configured to calculate a plurality of rise times using the plurality of digital current signals and one or more threshold currents received from the controller;
a memory coupled with the rise time measurement circuit, wherein the memory is configured to store the plurality of rise times; and
a rotor-angle estimation circuit coupled with the memory, wherein the rotor-angle estimation circuit is configured to calculate a rotor position relative to the stator of the PMSM by calculating one of a lowest average rise time, a lowest summed rise time, or a lowest weighted summed rise time using the plurality of rise times.
16. The system of claim 15 , wherein the one or more threshold currents comprise a first threshold current and a second threshold current, wherein the first threshold current and the second threshold current are related by an equation
I
th
1
=
4
3
I
th
2
where I th1 is the first threshold current and I th2 is the second threshold current.
17. The system of claim 15 , further comprising an amplifier configured to receive and to amplify the plurality of sensing voltage signals to form a plurality of amplified sensing voltage signals.
18. The system of claim 15 , wherein the plurality of voltage vectors is 12 voltage vectors.
19. The system of claim 15 , wherein the plurality of voltage vectors is 24 voltage vectors.