Torque and current control methods for switching variable electric drive vehicles

An electric motor control method, comprising:

• based on a motor torque request, a motor speed, a direct current (DC) bus voltage for an electric motor of a vehicle, generating a d-axis current command for the electric motor and a q-axis current command for the electric motor;
• generating voltage commands based on the d-axis current command and the q-axis current command;
• based on the voltage commands, selectively determining to transition a voltage operating state of a battery from a first voltage operating state to a second voltage operating state;
• in response to determining to transition the voltage operating state to the second voltage operating state, opening a plurality of switches of the battery for a dwell time;
• comparing (a) a battery parameter during the dwell time when the plurality of switches of the battery are open to (b) at least one of a predetermined voltage parameter and a predetermined current parameter;
• and
• based on the comparison, generating a switch control signal to transition at least one switch of the plurality of switches to cause the battery to transition to the second voltage operating state.

An electric motor control system, comprising:

• a current command module configured to, based on a motor torque request, a motor speed, a direct current (DC) bus voltage for an electric motor of a vehicle, generate a d-axis current command for the electric motor and a q-axis current command for the electric motor;
• a voltage command module configured to generate voltage commands based on the d-axis current command and the q-axis current command;
• and
• a battery switching control module configured to:
• determine a voltage operating state of a battery based on the voltage commands;
• compare a battery parameter to at least one of a predetermined voltage parameter and a predetermined current parameter during a dwell time when a plurality of switches of the battery are open;
• and
• generate a switch control signal to transition at least one switch of the plurality of switches to cause the battery to operate in the voltage operating state based on the comparison;
• an inverter module connected between the battery and the electric motor;
• and
• a capacitor disposed between the battery and the inverter module, wherein the capacitor stores energy provided by the battery,
• wherein a capacitance value of the capacitor is selected according to
• C=2*(Tdw−Δ(t))*(rpm*Nm*2pi/60)/([Vst2]2−[Vst1]2),
• where Tdw corresponds to the dwell time, Vst2 is a voltage corresponding to a second voltage operating state, Vst1 is a voltage corresponding to a first voltage operating state, rpm corresponds to revolutions per minute of the electric motor, Nm corresponds to a torque of the electric motor, and Δ(t) is a predetermined slack time parameter.