Powering electric vehicle accessory devices from back EMF generated by an electric motor
A controller generates a target motor torque and target accessory power information during operation of an electric vehicle. The target motor torque and target accessory power information maintain a DC-link of the electric vehicle powertrain within a safe DC-link operating range. The DC-link has a DC-link voltage that is used to supply an accessory device and a motor. The accessory device is disposed on the electric vehicle and includes vehicle indictors, hydraulics, or any other accessory involved in the operation of the vehicle. The motor drives the vehicle. The controller receives the DC-link voltage, motor speed, desired output torque information, desired accessory power information, and the safe DC-link operating range and generates therefrom the target motor torque and the target accessory power information.
1. A system comprising:
a DC-link;
an accessory device, wherein the accessory device is supplied by the DC-link;
a first voltage source connected to the DC-link;
a motor operable as a current source or a second voltage source; and
a controller, wherein the controller obtains a DC-link voltage, motor speed, desired output torque information, desired accessory power information, and a safe DC-link voltage operating range, wherein the controller controls the motor to operate as the current source when power is flowing between the first voltage source and the DC-link, wherein the controller controls the motor to operate as the second voltage source when power is not flowing between the first voltage source and the DC-link, and wherein target motor torque and target accessory power information are generated based in part on the DC-link voltage, the motor speed, the desired output torque information, the desired accessory power information, and the safe DC-link voltage operating range, and wherein the target motor torque and target accessory power information maintain the DC-link within the safe DC-link voltage operating range.
2. The system of claim 1 , wherein direct current supplied to the motor is generated from quadrature current that is proportional to motor torque, wherein the desired accessory power information includes a minimum required safety critical accessory power, a requested non-safety critical accessory power, and a total available accessory power, and wherein the controller obtains the safe DC-link voltage operating range by receiving information onto the controller or by reading information stored internally on the controller.
3. The system of claim 2 , wherein the total available accessory power includes available battery power.
4. The system of claim 2 , wherein the controller generates the target motor torque and the target accessory power information in accordance with a plurality of prioritized control objectives, wherein a first of the prioritized control objectives is to maintain the DC-link voltage within the safe DC-link voltage operating range, wherein a second of the prioritized control objectives is to maintain the minimum required safety critical accessory power, and wherein a third of the prioritized control objectives is to maintain motor torque in accordance with the desired output torque information.
5. The system of claim 4 , wherein the first of the prioritized control objectives has a higher priority than the second of the prioritized control objectives, and wherein the second of the prioritized control objectives has a higher priority than the third of the prioritized control objectives.
6. The system of claim 1 , wherein the target accessory power information includes target power for the accessory device.
7. The system of claim 1 , wherein the controller also generates a target direct axis current thereby maintaining the DC-link within the safe DC-link voltage operating range, and wherein the target direct axis current is generated based in part on the DC-link voltage, the motor speed, the desired output torque information, the desired accessory power information, and the safe DC-link voltage operating range.
8. The system of claim 1 , wherein the desired output torque information is determined by detecting an accelerator position.
9. The system of claim 1 , wherein a motor inverter is coupled between the motor and the DC-link.
10. A method comprising:
supplying an accessory device with a DC-link, wherein the DC-link has a DC-link voltage and a safe DC-link voltage operating range, and wherein the accessory device and a motor are disposed within an electric vehicle;
receiving the DC-link voltage, motor speed, desired output torque information, desired accessory power information, and the safe DC-link voltage operating range onto a controller; and
controlling the motor to operate as a voltage source when a fuse connected to an input voltage source is tripped and total input voltage loss occurs, wherein target motor torque and target accessory power information are generated based in part on the DC-link voltage, the motor speed, the desired output torque information, the desired accessory power information, and the safe DC-link voltage operating range, and wherein the target motor torque and target accessory power information maintain the DC-link within the safe DC-link voltage operating range.
11. The method of claim 10 , wherein the desired accessory power information includes a minimum required safety critical accessory power, a requested non-safety critical accessory power, and a total available accessory power.
12. The method of claim 11 , wherein the total available accessory power includes available battery power.
13. The method of claim 11 , wherein the controlling of the motor is performed by the controller such that the target motor torque and the target accessory power information are generated in accordance with a plurality of prioritized control objectives, wherein a first of the prioritized control objectives is to maintain the DC-link voltage within the safe DC-link voltage operating range, wherein a second of the prioritized control objectives is to maintain the minimum required safety critical accessory power, and wherein a third of the prioritized control objectives is to maintain motor torque in accordance with the desired output torque information.
14. The method of claim 13 , wherein the first of the prioritized control objectives has a higher priority than the second of the prioritized control objectives, and wherein the second of the prioritized control objectives has a higher priority than the third of the prioritized control objectives.
15. The method of claim 10 , wherein the target accessory power information includes target power for the accessory device.
16. The method of claim 10 , wherein the desired output torque information is determined by detecting an accelerator position.
17. The method of claim 10 , wherein the supplying of the accessory device involves a motor inverter coupled between the motor and the DC-link.
18. A method comprising:
supplying an accessory device with a DC-link, wherein the DC-link has a DC-link voltage and a safe DC-link voltage operating range, and wherein the accessory device and a motor are disposed within an electric vehicle;
receiving the DC-link voltage, motor speed, desired output torque information, desired accessory power information, and the safe DC-link voltage operating range onto a controller;
controlling the motor to operate as a voltage source when a fuse connected to an input voltage source is tripped and total input voltage loss occurs, wherein target motor torque and target accessory power information are generated based in part on the DC-link voltage, the motor speed, the desired output torque information, the desired accessory power information, and the safe DC-link voltage operating range, and wherein the target motor torque and target accessory power information maintain the DC-link within the safe DC-link voltage operating range; and
generating a target direct axis current, wherein the target direct axis current maintains the DC-link within the safe DC-link voltage operating range, and wherein the target direct axis current is generated based in part on the DC-link voltage, the motor speed, the desired output torque information, the desired accessory power information, and the safe DC-link voltage operating range.
19. A system comprising:
a DC-link that is coupled to supply an accessory device and a motor, wherein the DC-link, the motor, and the accessory device are disposed within an electric vehicle; and
means for controlling the motor to operate as a voltage source when a fuse connected to an input voltage source is tripped and total input voltage loss occurs, wherein target motor torque and target accessory power information are generated based in part on a DC-link voltage, a motor speed, a desired output torque information, a desired accessory power information, and the safe DC-link voltage operating range, and wherein the target motor torque and target accessory power information maintain the DC-link within the safe DC-link voltage operating range.
20. The system of claim 19 , wherein the means is a controller.