Electrical power conversion systems and methods suited for driving electric motors, and related systems such as propulsion systems, and vehicles employing same, are disclosed herein. In an example embodiment, the electrical power conversion system includes a plurality of series coupled inverters, each including respective first and second DC input terminals and also including respective AC output ports by which the inverters can respectively be coupled at least indirectly to motor winding sets. Additionally, the system includes a controller coupled to the inverters and configured to generate control signals that are respectively provided to the inverters. The control signals tend to cause respective AC output powers output from the respective AC output ports to be equal or substantially equal in a manner that tends to result in respective DC link voltage portions applied between the respective DC input terminals of the respective inverters being or becoming equal or substantially equal.

A multi-level high-speed adjustable speed drive has a plurality of modular multilevel, 3-phase inverter bridges, wherein the multilevel, 3-phase inverter bridges operate with fundamental frequency, f, wherein the multilevel, 3-phase inverter bridges include at least three levels, wherein the multilevel, 3-phase inverter bridges operate in Pulse-Width Modulation (PWM) mode with 9 to 21× or operating in Fundamental Frequency Mode (FFM), wherein inverter commutation frequency equals the fundamental frequency, wherein the multilevel, 3-phase inverters operate with split phase such that one group is displaced from the other by an angle, θ=60°/q, wherein the phase displacement of a harmonic component of order n between groups, θ.sub.n is nθ/q; a high-speed polyphase motor with phases arranged in q 3-phase groups; and electromagnetic means for blocking selected groups of harmonics while passing components at fundamental frequency, f, wherein the electromagnetic means includes coils carrying motor current linked by a magnetic core, wherein the electromagnetic means is interposed between the plurality of modular multilevel, 3-phase inverter bridges and the high-speed polyphase motor.

A method for controlling a three-phase electrical converter includes selecting a three-phase optimized pulse pattern from a table of pre-computed optimized pulse patterns based on a reference flux. The method includes determining a two-component optimal flux from the optimized pulse pattern and a one-component optimal third variable. The method includes determining a two-component flux error from a difference of the optimal flux and an estimated flux estimated based on measurements in the electrical converter. A one-component third variable error is determined from a difference of the optimal third variable and an estimated third variable. The optimized pulse pattern is modified by time-shifting switching instants of the optimized pulse pattern such that a cost function depending on the time-shifts is minimized. The method includes applying the modified optimized pulse pattern to the electrical converter.

A secondary magnetic excitation generator-motor device that inputs a first ignition pulse command to a three-level NPC power converter such that a detected excitation current value corresponds with an excitation current command value, the secondary magnetic excitation generator-motor device having a function of identifying a first phase, a second phase, or a third phase in descending order of a current absolute value, wherein a pulse switch to output an ignition pulse command to the three-level NPC power converter switches the ignition pulse command to the second ignition pulse command when a current absolute value exceeds a set overcurrent level 1, and switches the ignition pulse command to the first ignition pulse command when current absolute values for three phases are all equal to or smaller than a set overcurrent level 2.

A secondary magnetic excitation generator-motor device that inputs a first ignition pulse command to a three-level NPC power converter such that a detected excitation current value corresponds with an excitation current command value, the secondary magnetic excitation generator-motor device having a function of identifying a first phase, a second phase, or a third phase in descending order of a current absolute value, wherein a pulse switch to output an ignition pulse command to the three-level NPC power converter switches the ignition pulse command to the second ignition pulse command when a current absolute value exceeds a set overcurrent level 1, and switches the ignition pulse command to the first ignition pulse command when current absolute values for three phases are all equal to or smaller than a set overcurrent level 2.

A power supply device includes a storage battery; a capacitor unit having first and second capacitor; a three phase power converter, connected in parallel with the storage battery, each phase having first to fourth switching elements in series; three connection terminals electrically connectable to a three-phase AC charger; and a control unit, in a case where the three connection terminals and the three-phase AC charger are electrically connected between the first switching elements and the second switching elements for the respective three phases in the three-level inverter, before the storage battery is charged by means of the three-phase AC charger, charging the first capacitor with use of the storage battery and setting voltage of the second capacitor to 0 V.

A specialized variable speed drive of the present invention is capable of controlling a motor and increasing the efficiency of both an ACIM or DCBL motor by biasing operation in favor of a class AB mode. The variable speed drive may be configured with two gate drivers where one gate driver is a class D gate driver and the second gate driver is either a class AB gate driver or a class C gate driver. The system also operates to reduce electro-magnetic interference in the operation of motors while increasing the reliability of the overall VSD system.

A specialized variable speed drive of the present invention is capable of controlling a motor and increasing the efficiency of both an ACIM or DCBL motor by biasing operation in favor of a class AB mode. The variable speed drive may be configured with two gate drivers where one gate driver is a class D gate driver and the second gate driver is either a class AB gate driver or a class C gate driver. The system also operates to reduce electro-magnetic interference in the operation of motors while increasing the reliability of the overall VSD system.

A method for operating switching elements of a multilevel energy converter using at least three electric potentials and to which a multiphase electrical machine is connected. Switching elements of the multilevel energy converter are operated in a predefined clock mode by corresponding switching signals. The switching signals for the switching elements are each assigned to one of the phases and are determined in accordance with each desired voltage signal, in order to apply a phase voltage to each phase of the multiphase electrical machine. The switching signals are determined additionally in accordance with a predefined overlaying voltage signal such that an overlaying voltage dependent on the overlaying voltage signal is overlaid onto each phase voltage.

A method for operating switching elements of a multilevel energy converter using at least three electric potentials and to which a multiphase electrical machine is connected. Switching elements of the multilevel energy converter are operated in a predefined clock mode by corresponding switching signals. The switching signals for the switching elements are each assigned to one of the phases and are determined in accordance with each desired voltage signal, in order to apply a phase voltage to each phase of the multiphase electrical machine. The switching signals are determined additionally in accordance with a predefined overlaying voltage signal such that an overlaying voltage dependent on the overlaying voltage signal is overlaid onto each phase voltage.