Motor driving apparatus and method of controlling same

1. A motor driving apparatus including a first motor providing power to a first driving wheel of a vehicle and including a plurality of coils corresponding to a plurality of phases, respectively, and a second motor providing power to a second driving wheel of the vehicle and including a plurality of coils corresponding to a plurality of phases, respectively and including first ends connected to each other, the motor driving apparatus comprising: a first inverter connected to first ends of the coils of the first motor and including a plurality of first switching devices; a second inverter connected to second ends of the coils of the first motor and including a plurality of second switching devices; a third inverter connected to second ends of the coils of the second motor and including a plurality of third switching devices; and a controller configured to drive the second motor by performing pulse width control on the third switching devices when a problem occurs in the second inverter while driving the first motor in an open end winding mode in which pulse width modulation control is performed on the first switching devices and the second switching devices, wherein when the problem occurs in the second inverter in the open end winding mode, the controller is configured to connect the second ends of the coils of the first motor to each other and to drive the first motor in a Y-connection mode in which pulse width modulation control is performed on the first switching devices.

2. The motor driving apparatus of claim 1 , further including: a plurality of switches of which first ends are connected to the second ends of the coils of the first motor, respectively, and of which second ends are connected to each other, wherein when the problem occurs in the second inverter in the open-end winding mode, the controller is configured to turn on the switches and to drive the first motor in the Y-connection mode.

3. The motor driving apparatus of claim 1 , wherein when the problem occurs in the second inverter while the controller drives the first motor in the open-end winding mode, the controller is configured to divide and determine a preset entire required torque into a torque command of the first motor and a torque command of the second motor.

4. The motor driving apparatus of claim 3 , wherein when the problem occurs in the second inverter while the controller drives the first motor in the open end winding mode, the controller is configured to distribute and determine the preset entire required torque into the torque command of the first motor and the torque command of the second motor in accordance with a preset distribution ratio.

5. The motor driving apparatus of claim 3 , wherein the controller includes a torque limit table keeping a first torque limit value which is applied to the first motor in the open end winding mode, a second torque limit value which is applied to the first motor in the Y-connection mode, and a third torque limit value which is applied to the second motor when the second motor is driven by performing pulse width modulation control on the third switching devices.

6. The motor driving apparatus of claim 3 , wherein when the problem occurs in the second inverter while the controller drives the first motor in the open end winding mode, the controller is configured to control the first motor to output the second torque limit value and to control the second motor to output the third torque limit value when the torque command of the second motor divided and determined from the preset entire required torque is smaller than or a same as the third torque limit value and the torque command of the first motor divided and determined from the preset entire required torque is smaller than or a same as the second torque limit value.

7. The motor driving apparatus of claim 3 , wherein when the problem occurs in the second inverter while the controller drives the first motor in the open end winding mode, the controller is configured to change the torque command of the second motor into the third torque limit value and to determine the torque command of the first motor as a value obtained by subtracting the third torque limit value from the preset entire required torque when the torque command of the second motor divided and determined from the preset entire required torque is greater than the third torque limit value.

8. The motor driving apparatus of claim 7 , wherein

when the torque command of the first motor determined as the value obtained by subtracting the third torque limit value from the preset entire required torque is smaller than or a same as the second torque limit value, the controller is configured to control the first motor to output the value obtained by subtracting the third torque limit value from the preset entire required torque; and

when the torque command of the first motor determined as the value obtained by subtracting the third torque limit value from the preset entire required torque is greater than the second torque limit value, the controller is configured to control the first motor to output the second torque limit value.

9. The motor driving apparatus of claim 3 , wherein when the problem occurs in the second inverter when the controller drives the first motor in the open end winding mode, the controller is configured to change the torque command of the first motor into the second torque limit value and to determine the torque command of the second motor as a value obtained by subtracting the second torque limit value from the preset entire required torque when the torque command of the second motor divided and determined from the preset entire required torque is smaller than or a same as the third torque limit value and the torque command of the first motor divided and determined from the preset entire required torque is greater than the second torque limit value.

10. The motor driving apparatus of claim 9 , wherein

when the torque command of the second motor determined as the value obtained by subtracting the second torque limit value from the preset entire required torque is smaller than or a same as the third torque limit value, the controller is configured to control the second motor to output the value obtained by subtracting the second torque limit value from the preset entire required torque; and

when the torque command of the second motor determined as the value obtained by subtracting the second torque limit value from the preset entire required torque is greater than the third torque limit value, the controller is configured to control the second motor to output the third torque limit value.

11. A method of driving a motor which controls the motor driving apparatus of claim 1 , the method comprising:

recognizing, by the controller, that the problem has occurred in the second inverter while driving the first motor in the open end winding mode in which the pulse width modulation control is performed on the first switching devices and the second switch devices;

dividing and determining, by the controller, a preset entire required torque into a torque command of the first motor and a torque command of the second motor; and

correcting, by the controller, the torque command of the first motor and the second motor divided and determined from the preset entire required torque in accordance with a result of comparing the torque command of the first motor and the torque command of the second motor with a plurality of preset torque limit values, to obtain corrected values, and driving the first motor and the second motor according to the corrected values.

12. The method of claim 11 , wherein the driving connects the second ends of the coils of the first motor to each other and drives the first motor in a Y-connection mode in which pulse width modulation control is performed on the first switching devices.

13. The method of claim 12 ,

wherein the motor driving apparatus further includes a plurality of switches of which first ends are connected to the second ends of the coils of the first motor, respectively, and of which second ends are connected to each other, and

wherein the driving turns on the switches and drives the first motor in the Y-connection mode by the controller when the problem occurs in the second inverter in the open end winding mode.

14. The method of claim 11 , wherein the determining distributes and determines the preset entire required torque into the torque command of the first motor and the torque command of the second motor in accordance with a preset distribution ratio.

15. The method of claim 12 , wherein the controller includes a torque limit table keeping a first torque limit value which is applied to the first motor in the open end winding mode, a second torque limit value which is applied to the first motor in the Y-connection mode, and a third torque limit value which is applied to the second motor when the second motor is driven by performing pulse width modulation control on the third switching device.

16. The method of claim 15 , wherein the driving controls the first motor to output the second torque limit value and controls the second motor to output the third torque limit value by the controller when the torque command of the second motor divided and determined from the preset entire required torque is smaller than or a same as the third torque limit value and the torque command of the first motor divided and determined from the preset entire required torque is smaller than or a same as the second torque limit value.

17. The method of claim 15 , the driving changes the torque command of the second motor into the third torque limit value and determines the torque command of the first motor as a value obtained by subtracting the third torque limit value from the preset entire required torque by the controller when the torque command of the second motor divided and determined from the preset entire required torque is greater than the third torque limit value.

18. The method of claim 17 , wherein

when the torque command of the first motor determined as the value obtained by subtracting the third torque limit value from the preset entire required torque is smaller than or a same as the second torque limit value, the driving controls the first motor to output the value obtained by subtracting the third torque limit value from the preset entire required torque by the controller; and

when the torque command of the first motor determined as the value obtained by subtracting the third torque limit value from the preset entire required torque is greater than the second torque limit value, the driving controls the first motor to output the second torque limit value by the controller.

19. The method of claim 15 , wherein the driving changes the torque command of the first motor into the second torque limit value and determines the torque command of the second motor as a value obtained by subtracting the second torque limit value from the preset entire required torque by the controller when the torque command of the second motor divided and determined from the preset entire required torque is smaller than or a same as the third torque limit value and the torque command of the first motor divided and determined from the preset entire required torque is greater than the second torque limit value.