Start-up and restart of interior permanent magnet machines
View Patent ↗A method of starting a permanent magnet machine. A machine stator voltage in a stationary reference frame is sensed. An initial speed of a rotor of the machine is estimated based on the sensed voltage, and state variables of control algorithms are initialized based on the estimated initial speed. This method can provide smooth startup and/or restart at any speed.
1. A method of starting a permanent magnet machine controlled using one or more position detection modules that detect a position of a rotor of the machine, said method comprising:
sensing a machine stator voltage in a stationary reference frame;
estimating an initial speed of a rotor of the machine based on said sensed voltage; and
initializing at least one of the one or more position detection modules based on said estimated initial speed;
said sensing, estimating and initializing performed while at least one synchronous current regulator of the machine is disabled;
wherein said initializing comprises:
initializing a low-speed position detection module, and if said estimated initial speed exceeds a threshold value, initializing a high-speed position detection module;
wherein a low-speed position detection module is initialized, said method further comprising determining a polarity of an initial position of the rotor in accordance with:
sign
(
ω
)
=
sign
(
V
q
s
∫
V
d
s
ⅆ
t
-
V
d
s
∫
V
q
s
ⅆ
t
λ
P
M
2
)
where ω represents rotor speed, V d s represents the sensed voltage in a d-axis, V q s represents the sensed voltage in a q-axis, and λ PM represents magnetic flux linkage.
2. A method of starting a permanent magnet machine controlled using one or more position detection modules that detect a position of a rotor of the machine, said method comprising:
sensing a machine stator voltage in a stationary reference frame;
estimating an initial speed of a rotor of the machine based on said sensed voltage; and
initializing at least one of the one or more position detection modules based on said estimated initial speed;
said sensing, estimating and initializing performed while at least one synchronous current regulator of the machine is disabled;
wherein the initial speed is estimated in accordance with:
ω
=
V
d
s
2
+
V
q
s
2
λ
PM
where ω represents rotor speed, V d s represents the sensed voltage in a d-axis, V q s represents the sensed voltage in a q-axis, and λ PM represents magnetic flux linkage.
3. A method of starting an IPM machine comprising:
providing power to the machine and sensing one or more stator voltages;
estimating an initial speed and position of a rotor of the machine using the one or more sensed voltages while disabling regulation of current to the machine;
initiating current regulation based on said estimated initial rotor speed and position while disabling a torque command to the machine;
using said estimated initial rotor speed and position to determine at least one of low-speed and high-speed estimates of rotor speed and position; and
determining a polarity of the estimated initial rotor position in accordance with
sign
(
ω
)
=
sign
(
V
q
s
∫
V
d
s
ⅆ
t
-
V
d
s
∫
V
q
s
ⅆ
t
λ
P
M
2
)
where ω represents rotor speed, V d s represents the sensed voltage in a d-axis, V q s represents the sensed voltage in a q-axis, and λ PM represents magnetic flux linkage.
4. A method of starting an IPM machine comprising:
providing power to the machine and sensing one or more stator voltages;
estimating an initial speed and position of a rotor of the machine using the one or more sensed voltages while disabling regulation of current to the machine; and
initiating current regulation based on said estimated initial rotor speed and position while disabling a torque command to the machine;
wherein said estimating comprises estimating the initial speed in accordance with:
ω
=
V
d
s
2
+
V
q
s
2
λ
PM
where ω represents rotor speed, V d s represents the sensed voltage in a d-axis, V q s represents the sensed voltage in a q-axis, and λ PM represents magnetic flux linkage.
5. A method of starting an IPM machine comprising:
providing power to the machine and sensing one or more stator voltages;
estimating an initial speed and position of a rotor of the machine using the one or more sensed voltages while disabling regulation of current to the machine;
initiating current regulation based on said estimated initial rotor speed and position while disabling a torque command to the machine;
enabling a torque command to the machine; and
setting a bandwidth of the observer to a run-time setting; said enabling and setting performed after said initiating.
6. A drive system comprising:
an interior permanent magnet (IPM) machine having a rotor and a stator; and
a controller including one or more current regulators that regulate current commands to said machine, a gate driver that switches a signal to said stator, and one or more position detection modules that detect positioning of the rotor;
wherein said controller disables the gate drive switching, and after the disabling, performs the following:
measures d- and q-axis stator voltages in a stationary reference frame;
estimates an initial velocity of the rotor based on the measured voltages;
initializes at least one of the one or more position detection modules based on the estimated initial velocity; and
wherein said controller estimates the initial velocity in accordance with
ω
=
V
d
s
2
+
V
q
s
2
λ
PM
where ω represents rotor speed, V d s represents the measured voltage in a d-axis, V q s represents the measured voltage in a q-axis, and λ PM represents magnetic flux linkage.
7. A drive system comprising:
an interior permanent magnet (IPM) machine having a rotor and a stator; and
a controller including one or more current regulators that regulate current commands to said machine, a gate driver that switches a signal to said stator, and one or more position detection modules that detect positioning of the rotor;
wherein said controller disables the gate drive switching, and after the disabling, performs the following:
measures d- and q-axis stator voltages in a stationary reference frame;
estimates an initial velocity of the rotor based on the measured voltages;
initializes at least one of the one or more position detection modules based on the estimated initial velocity; and
an observer that provides a rotor speed and position based on an estimation by the one or more position detection modules; wherein said controller increases a bandwidth of said observer to accelerate the providing after said controller initializes said position detection modules.