Apparatus and method for controlling an electric machine
An electric machine control system and method for a vehicle, where an electric machine is arranged to be selectively coupleable to provide torque to at least one wheel of an axle of the vehicle. The control system comprises input means to receive at least one attribute signal indicative of one or more attributes of the vehicle, output means arranged to output a coupling signal to control coupling of the electric machine to the at least one wheel, and processing means arranged to determine a coupling state of the electric machine to the at least one wheel in dependence on the at least one attribute signal. The coupling signal is indicative of a change in the coupling state, and output of the coupling signal is deferred until expiry of a predetermined period of time since a last change in the coupling state indicated by the coupling signal.
1 . An electric machine control system for a vehicle, the electric machine control system comprising one or more controllers, wherein the vehicle comprises an electric machine arranged to be selectively coupleable to provide torque to at least one wheel of an axle of the vehicle, the control system comprising:
an input to receive at least one attribute signal indicative of one or more attributes of the vehicle, wherein the at least one attribute signal comprises a speed signal indicative of a speed of the vehicle;
an output arranged to output a coupling signal, wherein the output controls coupling of the electric machine to the at least one wheel of the axle based at least in part on the coupling signal; and
a processor arranged to determine a coupling state of the electric machine to the at least one wheel of the axle in dependence on the at least one attribute signal, wherein the processor is arranged to control the output to output the coupling signal indicative of the determined coupling state, wherein the processor is arranged to defer controlling the output to output the coupling signal indicative of a change in the coupling state until expiry of a predetermined period of time since a last change in the coupling state indicated by the coupling signal, wherein the last change in the coupling state comprises at least one of (i) a last request for a change in coupling state output by the one or more controllers, and (ii) a last successful change in coupling state,
wherein, if the speed is greater than a speed threshold, the change in the coupling state is from coupled to decoupled,
wherein the coupling signal is derived in determination of a fault associated with the vehicle, wherein a fault management module requests the coupling state of coupled or decoupled to control a state of the clutch to manage or resolve the fault associated with the vehicle.
2 . The control system of claim 1 , wherein the predetermined period of time is 30 seconds.
3 . The control system of claim 1 , wherein the predetermined period of time is 10 seconds.
4 . The control system of claim 1 , wherein the change in the coupling state is from coupled to decoupled.
5 . The control system of claim 1 , wherein the change in the coupling state is from decoupled to coupled.
6 . The control system of claim 1 , wherein the at least one attribute signal comprises a driving mode signal indicative of a driving mode of the vehicle.
7 . A powertrain comprising the system of claim 1 .
8 . A vehicle comprising the control system of claim 1 .
9 . The vehicle of claim 8 , wherein the electric machine is arranged to be selectively coupleable to provide torque to at least one wheel of a first axle of the vehicle, and the vehicle comprises a second motive power source arranged to provide torque to at least one wheel of a second axle of the vehicle.
10 . The vehicle of claim 9 , wherein the second motive power source comprises a second electric machine.
11 . The control system of claim 1 , wherein the processor is configured to output the coupling signal to effect the change in the coupling state between the electric machine and the at least one wheel of the axle in accordance with the determined coupling state.
12 . A method of controlling coupling of an electric machine to provide torque to at least one wheel of an axle of a vehicle, the method comprising:
receiving at least one attribute signal indicative of one or more attributes of the vehicle, wherein the at least one attribute signal comprises a speed signal indicative of a speed of the vehicle;
determining a coupling state of the electric machine to the at least one wheel of the axle in dependence on the at least one attribute signal;
outputting a coupling signal indicative of the determined coupling state to control coupling of the electric machine to the at least one wheel of the axle, wherein the outputting comprises deferring outputting the coupling signal indicative of a change in the coupling state until expiry of a predetermined period of time since a last change in the coupling state indicated by the coupling signal, wherein the last change in the coupling state comprises at least one of (i) a last request for a change in coupling state output by the one or more controllers, and (ii) a last successful change in coupling state, wherein, if the speed is greater than a speed threshold, the change in the coupling state is from coupled to decoupled; and
controlling coupling of the electric machine to the at least one wheel of the axle based at least in part on the coupling signal, the coupling signal derived in determination of a fault associated with the vehicle, wherein a fault management module requests the coupling state of coupled or decoupled to control a state of the clutch to manage or resolve the fault associated with the vehicle.
13 . The method of claim 12 , wherein the predetermined period of time is 30 seconds.
14 . The method of claim 12 , wherein the change in the coupling state is from coupled to decoupled.
15 . The method of claim 12 , wherein the change in the coupling state is from decoupled to coupled.
16 . The method of claim 12 , wherein the at least one attribute signal comprises a driving mode signal indicative of a driving mode of the vehicle.
17 . A non-transitory, computer-readable memory storing computer software which, when executed by a computer, is arranged to perform a method according to claim 12 .
18 . The method of claim 12 , wherein the predetermined period of time is 10 seconds.