Methods and apparatus for generating current commands for an interior permanent magnet (IPM) motor
View Patent ↗In one aspect, an apparatus includes a motor and inverter configured to provide input power to the motor. The apparatus may also include a data store comprising at least one entry including a first torque command, a first motor speed, and a first DC voltage value, where the first torque command and the first motor speed and the first DC voltage value are associated with a first current output and a processor. The processor receives a torque input, a DC voltage input, and a motor speed input and identifies the current output associated with the torque input, the DC voltage input, and the motor speed input based on another motor speed different than the motor speed input and another DC voltage different than the DC voltage input and the motor speed input, and output the determined current output to cause the inverter to provide the input power to the motor.
1. An apparatus comprising:
a motor;
an inverter configured to provide input power to the motor;
a DC power bus configured to provide input power to the inverter;
a data store comprising information defining inverter currents for producing different motor torque outputs at different motor speeds and different DC power bus voltages; and
a processor configured to:
receive a torque command, a DC power bus voltage measurement, and a motor speed measurement;
determine, using the data store, an inverter current command based at least in part on the torque command, the DC power bus voltage measurement, and the motor speed measurement, wherein the determining is further based at least in part on a motor speed value different than the motor speed measurement and a DC power bus voltage value different than the DC power bus voltage measurement; and,
control the inverter based at least in part on the determined inverter current command,
wherein the processor is further configured to identify a pre-stored inverter current command in the data store that is associated in the data store with the torque command, the DC power bus voltage value, and the motor speed value.
2. The apparatus of claim 1 , wherein the motor speed value is greater than the motor speed measurement.
3. The apparatus of claim 1 , wherein the motor speed value is less than the motor speed measurement.
4. The apparatus of claim 1 , wherein the inverter current command comprises a first component and a second component.
5. The apparatus of claim 1 , wherein the inverter current command is modified to account for a reference voltage.
6. An apparatus comprising:
a motor;
an inverter configured to provide input power to the motor;
a DC power bus configured to provide input power to the inverter;
a data store comprising information defining inverter currents for producing different motor torque outputs at different motor speeds and different DC power bus voltages; and
a processor configured to:
receive a torque command, a DC power bus voltage measurement, and a motor speed measurement;
determine, using the data store, an inverter current command based at least in part on the torque command, the DC power bus voltage measurement, and the motor speed measurement, wherein the determining is further based at least in part on a motor speed value different than the motor speed measurement and a DC power bus voltage value different than the DC power bus voltage measurement; and,
control the inverter based at least in part on the determined inverter current, wherein the motor speed value is determined at least in part by scaling the motor speed measurement by a ratio of the DC power bus voltage value and the DC power bus voltage measurement.
7. An apparatus comprising:
a motor;
an inverter configured to provide input power to the motor;
a DC power bus configured to provide input power to the inverter;
a data store comprising information defining inverter currents for producing different motor torque outputs at different motor speeds and different DC power bus voltages; and
a processor configured to:
receive a torque command, a DC power bus voltage measurement, and a motor speed measurement;
determine, using the data store, an inverter current command based at least in part on the torque command, the DC power bus voltage measurement, and the motor speed measurement, wherein the determining is further based at least in part on a motor speed value different than the motor speed measurement and a DC power bus voltage value different than the DC power bus voltage measurement; and,
control the inverter based at least in part on the determined inverter current, wherein the information in the data store is logically arranged as a plurality of entries in one or more lookup tables, wherein:
each lookup table of the one or more lookup tables comprises inverter current commands indexed by torque command and motor speed;
each lookup table of the one or more lookup tables is associated with a selected DC power bus voltage;
a first lookup table of the one or more lookup tables is associated with the DC power bus voltage value; and
the inverter current command is an entry in the first lookup table.
8. The apparatus of claim 7 , wherein the DC power bus voltage measurement is lower than the DC power bus voltage value.
9. The apparatus of claim 8 , wherein the first lookup table is the only lookup table in the data store.
10. The apparatus of claim 7 , wherein the DC power bus voltage measurement is higher than the first DC power bus voltage.
11. The apparatus of claim 10 , wherein the motor speed value is lower than the motor speed measurement.
12. The apparatus of claim 11 , wherein the first lookup table is the only lookup table in the data store.
13. An apparatus comprising:
a motor;
an inverter configured to provide input power to the motor;
a DC power bus configured to provide input power to the inverter;
a data store comprising information defining inverter currents for producing different motor torque outputs at different motor speeds and different DC power bus voltages; and
a processor configured to:
receive a torque command, a DC power bus voltage measurement, and a motor speed measurement;
determine, using the data store, an inverter current command based at least in part on the torque command, the DC power bus voltage measurement, and the motor speed measurement, wherein the determining is further based at least in part on a motor speed value different than the motor speed measurement and a DC power bus voltage value different than the DC power bus voltage measurement; and,
control the inverter based at least in part on the determined inverter current, wherein the received torque command, DC power bus voltage measurement, motor speed measurement, and motor speed value correspond to a field weakening region of the motor.
14. An apparatus comprising:
a motor;
an inverter configured to provide input power to the motor;
a DC power bus configured to provide input power to the inverter;
a data store comprising information defining inverter currents for producing different motor torque outputs at different motor speeds and different DC power bus voltages; and
a processor configured to:
receive a torque command, a DC power bus voltage measurement, and a motor speed measurement;
determine, using the data store, an inverter current command based at least in part on the torque command, the DC power bus voltage measurement, and the motor speed measurement, wherein the determining is further based at least in part on a motor speed value different than the motor speed measurement and a DC power bus voltage value different than the DC power bus voltage measurement; and,
control the inverter based at least in part on the determined inverter current, wherein
the received torque command, DC power bus voltage measurement, and
motor speed measurement correspond to a constant torque region of the motor, and
the motor speed value is determined at least in part by scaling the motor speed measurement.