Granted Patent B2

US 8,054,030 · App. 12/017,817 · Granted Nov 8, 2011

Abstract

Claims (67)

1. A permanent magnet AC (PMAC) motor system, comprising:

a PMAC motor including a rotor;

a three-phase inverter coupled to the PMAC motor and configured to provide a voltage to the PMAC motor; and

a controller coupled to the three-phase inverter and to the PMAC motor, wherein the controller comprises:

control logic configured to perform a sensorless control algorithm for controlling the PMAC motor;

start/restart logic configured to determine when to start/restart the sensorless control algorithm;

drive logic configured to drive the voltage to substantially zero volts in response to a determined start/restart of the sensorless control algorithm;

current detect logic configured to detect current in each phase of the three-phase inverter when the voltage is substantially zero volts; and

estimation logic configured to estimate a first position of the rotor, a speed of the PMAC motor, or both based on the detected current.

2. The PMAC system of claim 1 , further comprising input logic configured to input the estimated first position, the estimated speed, or both into the sensorless control algorithm in response to the determined start/restart of the sensorless control algorithm.

3. The PMAC system of claim 1 , wherein the three-phase inverter comprises a plurality of high-side switches coupled to the drive logic and a plurality of low-side switches coupled to the drive logic, and wherein the drive logic comprises:

a first switch logic configured to switch ON each of the plurality of high-side switches and switch OFF each of the plurality of low-side switches to drive the voltage to the substantially zero volts; and

a second switch logic configured to switch ON each of the plurality of low-side switches and switch OFF each of the plurality of high-side switches to drive the voltage to the substantially zero volts.

4. The PMAC system of claim 1 , wherein the detect current logic comprises a first detect logic configured to detect a first amount of current in each phase at a beginning of a first clock cycle, and wherein the estimation logic comprises a first position logic configured to detect the first position based on the detected first amount of current.

5. The PMAC system of claim 4 , wherein the detect current logic further comprises a second detect logic configured to detect a second amount of current in each phase at a beginning of a second clock cycle, and wherein the estimation logic further comprises:

a second position logic configured to detect a second position based on the detected second amount of current; and

direction estimation logic configured to estimate a direction of the speed based on the first position and the second position.

6. The PMAC system of claim 5 , wherein the direction estimation logic comprises:

compare logic configured to compare the first position and the second position;

negative speed logic configured to determine that the speed is in a negative direction if the first position includes a value greater than the second position; and

positive speed logic configured to determine that the speed is in a positive direction if the second position includes a value greater than the first position.

7. A method for starting or restarting a sensorless control algorithm for controlling a permanent magnet AC (PMAC) motor including a rotor coupled to a three-phase inverter having a voltage and a plurality of high-side switches and a plurality of low-side switches, the method comprising the steps of:

determining to start/restart the sensorless control algorithm;

modifying the voltage in response to the determined start/restart of the sensorless control algorithm, wherein modifying the voltage comprises switching ON each of the plurality of high-side switches or each of the plurality of low-side switches;

detecting current in each phase of the three-phase inverter after the voltage is modified to substantially zero volts; and

estimating a first position of the rotor, a speed of the PMAC motor, or both based on the detected current.

8. A method for starting or restarting a sensorless control algorithm for controlling a permanent magnet AC (PMAC) motor including a rotor coupled to a three-phase inverter having a voltage, the method comprising the steps of:

determining to start/restart the sensorless control algorithm;

modifying the voltage in response to the determined start/restart of the sensorless control algorithm by decreasing or increasing the voltage to substantially zero volts;

detecting current in each phase of the three-phase inverter after the voltage is modified; and

estimating a first position of the rotor, a speed of the PMAC motor, or both based on the detected current.

9. The method of claim 8 , further comprising the steps of:

inputting the estimated first position, the estimated speed, or both into the sensorless control algorithm; and

starting or restarting the sensorless control algorithm using the estimated first position, the estimated speed, or both as initial conditions.

10. A method for starting or restarting a sensorless control algorithm for controlling a permanent magnet AC (PMAC) motor including a rotor coupled to a three-phase inverter having a voltage, the method comprising the steps of:

determining to start/restart the sensorless control algorithm;

modifying the voltage in response to the determined start/restart of the sensorless control algorithm;

detecting current in each phase of the three-phase inverter after the voltage is modified, wherein the detecting current comprises detecting a first amount of current in each phase at a beginning of a first clock cycle; and

estimating a first position of the rotor, a speed of the PMAC motor, or both based on the detected current, wherein the estimating a first position comprises estimating the first position based on the detected first amount of current.

11. The method of claim 10 , wherein the detecting current step further comprises the step of:

detecting a second amount of current in each phase at a beginning of a second clock cycle, and wherein the estimating step further comprises the steps of:

estimating a second position based on the detected second amount of current; and

determining a direction of the speed based on the first position and the second position.

12. The method of claim 11 , wherein the determining the direction step comprises the steps of:

comparing the first position and the second position;

determining that the speed is in a negative direction if the first position includes a value greater than the second position; and

determining that the speed is in a positive direction if the second position includes a value greater than the first position.

13. A controller being coupled to a permanent magnet AC (PMAC) motor having a rotor and to a three-phase inverter having a voltage coupled to the PMAC motor, the controller comprising:

means for performing a sensorless control algorithm utilized to control the PMAC motor, the performing means configured to be coupled to the rotor and the PMAC motor;

means for determining to when start/restart the sensorless control algorithm in communication with the performing means;

means for driving the voltage to substantially zero volts in response to a determined start/restart of the sensorless control algorithm in communication with the determining means;

means for detecting current in each phase of the three-phase inverter when the voltage is substantially zero volts in communication with the driving means; and

means for estimating a first position of the rotor, a speed of the PMAC motor, or both based on the detected current configured to be coupled to the rotor and the PMAC motor.

14. The controller of claim 13 , further comprising:

input means for inputting the estimated first position, the estimated speed, or both into the sensorless control algorithm; and

start/restart means for starting or restarting the sensorless control algorithm using the estimated first position, the estimated speed, or both as initial conditions.

15. The controller of claim 13 , wherein the three-phase inverter comprises a plurality of high-side switches capable of being coupled to the driving means and a plurality of low-side switches capable of being coupled to the driving means, and wherein the driving means comprises:

means for switching ON each of the plurality of high-side switches and switching OFF each of the plurality of low-side switches to drive the voltage to the substantially zero volts; and

means for switching ON each of the plurality of low-side switches and switching OFF each of the plurality of high-side switches to drive the voltage to the substantially zero volts.

16. The controller of claim 13 , wherein the detecting current means comprises means for detecting a first amount of current in each phase at a beginning of a first clock cycle, and wherein the estimating means comprises means for estimating the first position based on the detected first amount of current.

17. The controller of claim 16 , wherein the detecting current means further comprises means for detecting a second amount of current in each phase at a beginning of a second clock cycle, and wherein the estimating means further comprises:

means for estimating a second position based on the detected second amount of current; and

means for estimating a direction of the speed based on the first position and the second position.

18. The controller of claim 17 , wherein the direction estimating means comprises:

means for comparing the first position and the second position;

means for determining that the speed is in a negative direction if the first position includes a value greater than the second position; and

means for determining that the speed is in a positive direction if the second position includes a value greater than the first position.

Assignments (12)