A system and method for controlling an electric machine via an inverter comprises an speed estimator that is configured to estimate a rotor speed of an electric motor to determine whether to control the inverter to operate the electric motor in a first mode or a second mode. For example, the first mode comprises a current-frequency control mode and the second mode comprises a back electromagnetic force (BEMF) mode. An electronic data processor or controller is configured to determine a first (current) command associated with a first mode of operating the electric motor, if the estimated rotor speed is a less than a speed threshold. The electronic data processor or controller is configured to determine a second (current) command associated with a second mode of operating the electric motor if the estimated rotor speed is equal to or greater than the speed threshold.

A system and method for controlling an electric machine via an inverter comprises an speed estimator that is configured to estimate a rotor speed of an electric motor to determine whether to control the inverter to operate the electric motor in a first mode or a second mode. For example, the first mode comprises a current-frequency control mode and the second mode comprises a back electromagnetic force (BEMF) mode. An electronic data processor or controller is configured to determine a first (current) command associated with a first mode of operating the electric motor, if the estimated rotor speed is a less than a speed threshold. The electronic data processor or controller is configured to determine a second (current) command associated with a second mode of operating the electric motor if the estimated rotor speed is equal to or greater than the speed threshold.

A voltage difference is determined between the observed voltage and a reference direct current bus voltage. A quadrature-axis (q-axis) voltage command is outputted based on a current difference derived from the voltage difference. A commanded direct-axis (d-axis) voltage is determined based on a measured d-axis current and a determined d-axis reference current derived from a mathematical relationship between d-axis residual voltage, the observed voltage and the commanded q-axis voltage, where residual voltage is proportional to a function of the observed voltage and the commanded q-axis voltage. An inverse Parks transformation module or a data processor provides one or more phase voltage command based on inverse Parks transform of the commanded voltages.

A capacitor is connected between the direct current voltage terminals. Switched terminals of a first switch and a second switch are coupled in series, between the direct current voltage terminals. An electric machine or generator has one or more windings and a first phase output terminal associated with the switched terminals. A first set of blocking diodes are cascaded in series and second set of blocking diodes are cascaded in series. A first voltage supply provides a first output voltage level and a second output level switchable to the first control terminal, where the first output level is distinct from the second output level. A second voltage supply provides the first output voltage level and the second output level switchable to the second control terminal.

A motor flux weakening control method with data map creation is provided. The method estimates a phase angle between a dq electric current vector and a d-axis based on a speed of the motor; estimates an input direct current; repeats the estimating of the phase angle and the direct current while decreasing a magnitude of the dq electric current vector based on a difference between the estimated direct current and a preset direct current limitation value; and interrupts the repeating of the estimating of the phase angle and the estimating of the direct current when the direct current and the preset direct current limitation value are equal, and stores a relationship between the speed of the motor, the direct current voltage, the phase angle, and the magnitude of the dq electric current vector, when the estimated direct current and the preset direct current limitation value are equal.

A motor flux weakening control method with data map creation is provided. The method estimates a phase angle between a dq electric current vector and a d-axis based on a speed of the motor; estimates an input direct current; repeats the estimating of the phase angle and the direct current while decreasing a magnitude of the dq electric current vector based on a difference between the estimated direct current and a preset direct current limitation value; and interrupts the repeating of the estimating of the phase angle and the estimating of the direct current when the direct current and the preset direct current limitation value are equal, and stores a relationship between the speed of the motor, the direct current voltage, the phase angle, and the magnitude of the dq electric current vector, when the estimated direct current and the preset direct current limitation value are equal.

An electric vehicle propulsion control device includes a power converter that applies an alternating-current voltage to an induction machine and a controller that controls the power converter based on an external operation command. The controller includes a first calculation unit. The first calculation unit calculates, from current information (id and iq) detected at the induction machine and current command values (id*1 and iq*1) that are based on the operation command, a d-axis voltage command (Vd*1) and a q-axis voltage command (Vq*1) for the power converter, and a primary magnetic flux φds and a secondary magnetic flux φdr of the induction machine. The first calculation unit also adds to or subtracts from a term including the q-axis voltage command (Vq*1) an interference term stemming from the d-axis voltage command (Vd*1) in calculating a first speed ω1 that is a free-run speed of the induction machine.

An electric vehicle propulsion control device includes a power converter that applies an alternating-current voltage to an induction machine and a controller that controls the power converter based on an external operation command. The controller includes a first calculation unit. The first calculation unit calculates, from current information (id and iq) detected at the induction machine and current command values (id*1 and iq*1) that are based on the operation command, a d-axis voltage command (Vd*1) and a q-axis voltage command (Vq*1) for the power converter, and a primary magnetic flux φds and a secondary magnetic flux φdr of the induction machine. The first calculation unit also adds to or subtracts from a term including the q-axis voltage command (Vq*1) an interference term stemming from the d-axis voltage command (Vd*1) in calculating a first speed ω1 that is a free-run speed of the induction machine.

A system may include an inverter configured to convert a direct current (DC) voltage to an alternating current (AC) voltage. The system may also include a control system communicatively coupled to the inverter. The control system may receive a torque current feedback from a motor and may generate, based on the torque current feedback, a command torque current and a command flux current. The control system may generate, based on the command torque current and the command flux current, a command torque voltage and a command flux voltage and may generate, based on a slip frequency and a rotor frequency, a command frequency. The control system may determine one or more operating parameters for the inverter based on the command frequency, the command torque voltage, and the command flux voltage and may control the inverter based on the one or more operating parameters.

A system may include an inverter configured to convert a direct current (DC) voltage to an alternating current (AC) voltage. The system may also include a control system communicatively coupled to the inverter. The control system may receive a torque current feedback from a motor and may generate, based on the torque current feedback, a command torque current and a command flux current. The control system may generate, based on the command torque current and the command flux current, a command torque voltage and a command flux voltage and may generate, based on a slip frequency and a rotor frequency, a command frequency. The control system may determine one or more operating parameters for the inverter based on the command frequency, the command torque voltage, and the command flux voltage and may control the inverter based on the one or more operating parameters.