DRIVE DEVICE FOR AN ELECTRIC VEHICLE, ELECTRIC VEHICLE AND METHOD FOR OPERATING A DRIVE DEVICE IN AN ELECTRIC VEHICLE
Drive device for an electric vehicle, including an electric machine with a stator and a rotor, and a temperature determination device. The electric machine has machine characteristics, according to which one value of a torque (T) is assigned to each operating point being a pair of values of the d- and the q-component, the power converter device being configured to receive the torque command and to determine a pair of setpoints (i d * , i q * ) for the d- and the q-component corresponding to one operating point that is assigned to the desired torque (T*). Upon receiving the first and second information states, the pair of setpoints is determined according to a first and second operating modes. The power converter device being configured to generate the multiphase current depending on the pair of setpoints.
1 . Drive device for an electric vehicle, comprising:
an electric machine with a stator and with a rotor-being arranged rotatably relative to the stator;
a temperature determination device configured to determine a temperature information being representative of a temperature (ϑ) of the rotor, the temperature information having at least two information states, a first one of the information states being representative of a first temperature and a second one of the information states being representative of a second temperature being higher than the first temperature; and
a power converter device configured to provide a multiphase current (i) to the stator, having an input for a torque command representing a desired torque (T*) to be provided by the rotor and being operable according to a first operating mode and according to a second operating mode, the multiphase current (i) being representable by a space vector with a d-component and a q-component in a rotor flux oriented coordinate system;
the electric machine having machine characteristics, according to which one value of a torque (T) provided by the rotor is assigned to each one of multiple operating points, each operating point being a pair of values of the d-component and the q-component, the power converter device being configured to receive the torque command and to determine a pair of setpoints
(
i
d
*
,
i
q
*
)
for the d-component and the q-component corresponding to one of the operating points that is assigned to the desired torque (T*), wherein, upon receiving the first information state, the pair of setpoints
(
i
d
*
,
i
q
*
)
is determined according to the first operating mode, and, upon receiving the second information state, the pair of setpoints
(
i
d
*
,
i
q
*
)
is determined according to the second operating mode, in which the setpoint
(
i
d
*
)
for the d-component has a higher value that the setpoint
(
i
d
*
)
for the d-component that is determined in the first operating mode at the desired torque (T*) and in which the setpoint
(
i
q
*
)
for the q-component has a lower value than the setpoint
(
i
q
*
)
for the q-component that is determined in the first operating mode at the desired torque (T*), wherein the power converter device is further configured to generate the multiphase current depending on the pair of setpoints
(
i
d
*
,
i
q
*
)
.
2 . Drive device according to claim 1 , wherein
the machine characteristics have MTPC operating points assigned to a respective value of the torque (T).
3 . Drive device according to claim 2 , wherein
in the second operating state, the setpoint
(
i
d
*
)
for the d-component has a higher value than the d-component of the MTPC operating point that is assigned to the desired torque (T*) and/or the setpoint for the q-component
(
i
q
*
)
has a lower value than the q-component of the MTPC operating point that is assigned to the desired torque (T*).
4 . Drive device according to claim 2 , wherein
in the first operating mode, the pair of setpoints
(
i
d
*
,
i
q
*
)
correspond to the MTPC operating point that is assigned to the desired torque (T*).
5 . Drive device according to claim 2 , wherein
the MTPC operating points comprise those operating points, at which the torque (T) is maximal for a respective absolute value of the space vector.
6 . Drive device according to claim 1 , wherein
the power converter device is further configured to evaluate a condition, according to which the temperature (ϑ) of the rotor reaches or exceeds a predetermined temperature threshold value being higher than the first temperature and lower than the second temperature, and to operate according to the first operating mode if the condition is not fulfilled and/or to operate according to the second operating mode if the condition is fulfilled.
7 . Drive device according to claim 1 , wherein
in the second operating mode, upon receiving an information state representing a temperature (ϑ) of the rotor being higher than the second temperature, the setpoint
(
i
d
*
)
for d-component is determined with a higher value and the setpoint
(
i
q
*
)
for the q-component is determined with a lower value than upon receiving the second information state and/or, upon receiving an information state representing a temperature (ϑ) of the rotor being lower than the second temperature and higher than the first temperature, the setpoint for d-component
(
i
d
*
)
is determined with a lower value and the setpoint for the q-component
(
i
q
*
)
is determined with a higher value than upon receiving the second information state.
8 . Drive device according to claim 1 , wherein
in the second operating mode, the pair of setpoints
(
i
d
*
,
i
q
*
)
lies within a predetermined operating range of the machine characteristics.
9 . Drive device according to claim 8 , wherein
the operating range is chosen such that an efficiency measure for all operating points inside the operating range does not undercut a maximum of the efficiency measure assigned to the same torque (T) as the respective operating point more than 10 percent, preferably 5 percent, more preferably 2 percent.
10 . Drive device according to claim 9 , wherein
the efficiency measure is a ratio of a mechanical output power of the electric machine to an electric input power of the electric machine.
11 . Drive device according to claim 8 , wherein
the operating range is bounded by a combination of the d-component and the q-component and/or by a predefined maximum of the absolute value of the space vector.
12 . Drive device according to claim 1 , wherein
the temperature determination device comprises a temperature sensor configured to provide sensor signals,
the temperature sensor being arranged at the rotor, the temperature determination device being configured to provide the sensor signals as temperature information, or
the temperature sensor being arranged at the electric machine preferably at the stator, the temperature determination device being configured to estimate the temperature (ϑ) of the rotor based on the sensor signals and on a thermal model of the electric machine.
13 . Drive device according to claim 1 , wherein
the electric machine is an induction motor.
14 . Electric vehicle, comprising a drive device according to claim 1 , the drive device being configured to propel the electric vehicle.
15 . Method for operating a drive device in an electric vehicle, the drive device comprising: an electric machine with a stator and with a rotor being arranged rotatably relative to the stator; a temperature determination device; and a power converter device configured to provide a multiphase current (i) to the stator, having an input and being operable according to a first operating mode and a second operating mode; the multiphase current (i) being representable by a space vector with a d-component and a q-component in a rotor flux oriented coordinate system; the electric machine having machine characteristics, according to which one value of a torque (T) provided by the rotor is assigned to each one of multiple operating points, each operating point being a pair of values of the d-component and the q-component; the method comprising steps of:
determining, by the temperature determination device, a temperature information being representative of a temperature (ϑ) of the rotor, the temperature information having at least two information states, a first one of the information states being representative of a first temperature and a second one of the information states being representative of second temperature being higher than the first temperature;
receiving, at the input of the power converter device, a torque command representing a desired torque (T*) to be provided by the rotor;
determining, by the power converter device, a pair of setpoints
(
i
d
*
,
i
q
*
)
for the d-component and the q-component corresponding to one of the operating points that is assigned to the desired torque (T*), wherein, upon receiving the first information state, the pair of setpoints
(
i
d
*
,
i
q
*
)
is determined according to the first operating mode, and, upon receiving the second information state, the pair of setpoints
(
i
d
*
,
i
q
*
)
is determined according to the second operating mode, in which the setpoint
(
i
d
*
)
for the d-component has a higher value than the setpoint for the d-component
(
i
d
*
)
that is determined in the first operating mode at the desired torque (T*) and in which the setpoint for the q-component
(
i
q
*
)
has a lower value that the setpoint for the q-component
(
i
q
*
)
that is determined in the first operating mode at the desired torque (T*); and
generating, by the power converter device, the multiphase current (i) depending on the pair of setpoints
(
i
d
*
,
i
q
*
)
.
16 . Drive device according to claim 3 , wherein
in the first operating mode, the pair of setpoints
(
i
d
*
,
i
q
*
)
correspond to the MTPC operating point that is assigned to the desired torque (T*).
17 . Drive device according to claim 3 , wherein
the MTPC operating points comprise those operating points, at which the torque (T) is maximal for a respective absolute value of the space vector.
18 . Drive device according to claim 2 , wherein
the power converter device is further configured to evaluate a condition, according to which the temperature (ϑ) of the rotor reaches or exceeds a predetermined temperature threshold value being higher than the first temperature and lower than the second temperature, and to operate according to the first operating mode if the condition is not fulfilled and/or to operate according to the second operating mode if the condition is fulfilled.
19 . Drive device according to claim 2 , wherein
in the second operating mode, upon receiving an information state representing a temperature (ϑ) of the rotor being higher than the second temperature, the setpoint
(
i
d
*
)
for d-component is determined with a higher value and the setpoint
(
i
q
*
)
for the q-component is determined with a lower value than upon receiving the second information state and/or, upon receiving an information state representing a temperature (ϑ) of the rotor being lower than the second temperature and higher than the first temperature, the setpoint for d-component
(
i
d
*
)
is determined with a lower value and the setpoint for the q-component
(
i
q
*
)
is determined with a higher value than upon receiving the second information state.
20 . Drive device according to claim 2 , wherein
in the second operating mode, the pair of setpoints
(
i
d
*
,
i
q
*
)
lies within a predetermined operating range of the machine characteristics.