A method for controlling a first inverter and a second inverter that are coupled to variable DC voltage bus, in which inverter inputs are coupled to a variable direct current voltage bus and in inverter outputs are connected to a first variable load of a first electric machine and a second variable load of a second electric machine, the method comprising: measuring an observed voltage level of the variable DC voltage bus for a time interval; in a first inverter, determining a first torque command and/or first speed command comprising a first direct-axis current/voltage command and a first quadrature-axis current/voltage command demanded by real time, transient load conditions on the first electric machine to maintain operation for the time interval based on the first variable load of the first electric machine; in a second inverter, determining a second torque command and/or second speed command comprising a second direct-axis current/voltage command and a second quadrature-axis current/voltage command demanded by real time, transient load conditions on the second electric machine to maintain operation for the time interval based on the second variable load of the second electric machine; estimating a minimum required variable DC bus voltage based on the first direct-axis current/voltage command, the first quadrature-axis current/voltage command, the second direct-axis current/voltage command, and the second quadrature-axis current/voltage command for the time interval; and providing the estimated minimum required variable DC bus voltage to a voltage regulator to adjust the observed voltage level of the variable DC voltage bus to the estimated minimum required variable DC bus voltage to maintain the operation, as commanded by the voltage/current commands, of the first electric machine under the first variable load and the second electric machine under the second variable load at the time interval, characterized in that the voltage regulator has a configurable slew rate and that the voltage command provided to the voltage regulator comprises a slew rate meeting or exceeding a minimum slew rate required to satisfy the commanded current/voltage in real time for the time interval for the first electric machine and the second electric machine. measuring an observed voltage level of the variable DC voltage bus for a time interval; in a first inverter, determining a first torque command and/or first speed command comprising a first direct-axis current/voltage command and a first quadrature-axis current/voltage command demanded by real time, transient load conditions on the first electric machine to maintain operation for the time interval based on the first variable load of the first electric machine; in a second inverter, determining a second torque command and/or second speed command comprising a second direct-axis current/voltage command and a second quadrature-axis current/voltage command demanded by real time, transient load conditions on the second electric machine to maintain operation for the time interval based on the second variable load of the second electric machine; estimating a minimum required variable DC bus voltage based on the first direct-axis current/voltage command, the first quadrature-axis current/voltage command, the second direct-axis current/voltage command, and the second quadrature-axis current/voltage command for the time interval; and providing the estimated minimum required variable DC bus voltage to a voltage regulator to adjust the observed voltage level of the variable DC voltage bus to the estimated minimum required variable DC bus voltage to maintain the operation, as commanded by the voltage/current commands, of the first electric machine under the first variable load and the second electric machine under the second variable load at the time interval, characterized in that the voltage regulator has a configurable slew rate and that the voltage command provided to the voltage regulator comprises a slew rate meeting or exceeding a minimum slew rate required to satisfy the commanded current/voltage in real time for the time interval for the first electric machine and the second electric machine.