A modulation routine in a motor drive under lightly loaded conditions which prevents DC bus voltage pump-up includes both active states and zero states. In a first zero state, each phase of the motor is connected to a negative rail of the DC bus, and in a second zero state, each phase of the motor is connected to a positive rail of the DC bus. When motor is lightly loaded or unloaded such that DC bus voltage pump-up may occur, the two zero states are utilized in an uneven manner. The specific division of the zero state between the first and second zero states may be selected in a manner that prevents the DC bus voltage pump-up from occurring.

An embodiment relates to a method for operating a three-phase machine including a rotor and a stator connected to a three-phase network. The stator is connected to the three-phase network via a first semiconductor circuit arrangement for forming a first rotational field rotating in a first direction of rotation in the stator and via a second semiconductor circuit arrangement for forming a second rotational field rotating in a direction of rotation opposite to the first direction of rotation in the stator. The three-phase machine further includes a controller. The method includes controlling, via the controller, semiconductors of the first and second semiconductor circuit arrangement to accelerate the rotor by current pulses of both the first rotational field and second rotational field in the first direction of rotation.

A power conversion device, mounted on a motor vehicle, has a battery, a power converter, a reactor and a control unit. The power conversion device boosts a battery voltage of the battery, and supplies a boosted voltage to a motor generator mounted on a motor vehicle. The power conversion device transmits electric power generated by the motor generator and supplies the generated electric power to the battery through the power converter. The power converter has an upper arm and a lower arm. The upper arm has upper arm side switching elements. The lower arm has lower arm side switching elements which are directly connected to the respective upper arm side switching elements. At least one of the upper arm side switching elements is composed of a MOS FET and at least one of the lower arm side switching elements is composed of an IGBT.

A motor starter and a method for starting an electric motor are disclosed. In an embodiment, the motor starter includes a phase gating unit and a control unit. The phase gating unit is configured to be deactivated via the control unit after an activity period of the phase gating unit has elapsed and is configured to be deactivated during operation after the activity period has elapsed.

The invention relates to a motor starter (10) for an electric motor (20), wherein the motor starter (10) comprises a first and a second phase (12, 14). Said motor starter and electric motor each have an associated switching apparatus (29, 31) which each have an electromechanical switch (22, 24) and a semiconductor switch (23, 25) connected to form a bypass circuit. The electromechanical switches (22, 24) and the semiconductor switches (23, 25) are designed to be separately operable by a control unit (40), and the first and the second phase (12, 14) are connected to a passive overcurrent protection means (30). The passive overcurrent protection means (30) has a fuse (32, 34, 36) for each phase. According to the invention, a measuring apparatus (42, 44) is arranged in at least one of the phases (12, 14) along the phase direction directly between the passive overcurrent protection means (30) and at least one of the switching apparatuses (29, 31). The invention further relates to diagnosis methods (100, 200, 300) with which defects in the motor starter (10) can be diagnosed during an activation sequence.

A power conversion device includes first and second inverters connectable to at least one of first and second coil groups, a first separation relay circuit connected to the first inverter, a second separation relay circuit connected to the second inverter, a third separation relay circuit connected between the first separation relay circuit and the first coil group, a fourth separation relay circuit connected between the second separation relay circuit and the second coil group, and n connection lines to, for each phase, connect n nodes between the first and third separation relay circuits and n nodes between the second and fourth separation relay circuits, where n is an integer of 3 or more.

A power converter for an electric power system comprises a switching circuit (102) for supplying, in a first operating mode of the power converter, voltages for driving a rotating electric machine. The power converter comprises a contactor system (110) and a controller (109) for using, in a second operating mode of the power converter, the switching circuit and at least one of windings (115) of the rotating electric machine as a voltage-decreasing direct voltage converter between direct voltage terminals of the power converter. Therefore, the switching circuit of the power converter can be utilized both for driving the rotating electric machine and, for example, for charging a battery element connected to a direct voltage terminal of the power converter.

A power tool includes a motor and a power supply for supplying power to the motor. A driving circuit is connected to the motor. A voltage detection unit is used for detecting the voltage of the motor. A controller is configured to perform the following operations: if the motor voltage is greater than or equal to a preset voltage, the driving circuit will apply a voltage to the motor with a second slope, wherein the value range of the second slope is from 0 to 0.3. The disclosure also discloses a control method for starting under load of a power tool.

A system for controlling an AC motor is provided. The system comprises an electrical connection path for connecting an electrical input of the AC motor to a first phase of alternating current from an electric power supply. The system also comprises two or more motor controllers, each motor controller is located on the electrical connection path between the electric power supply and the AC motor and is operable to regulate current of the first phase passing through it. Each motor controller is connected in parallel, relative to the other motor controllers, to the electrical connection path. At least one processor is configured to control the motor controllers to repeatedly change which of the motor controllers current of the first phase passes through, such that at any given time current of the first phase only passes through one of the motor controllers. A corresponding method is also provided.

Gate driver circuit for driving power transistor includes: gate line to be connected to the transistor; source line to be connected to the transistor; first current source sourcing current to the gate line; and second current source sinking current from the gate line, wherein the first current source includes: first reference impedance element connected to power supply line; first reference transistor installed between the first reference impedance element and the gate line; first error amplifier having output connected to gate of the first reference transistor, one input connected to the first reference impedance element, and the other input where first reference voltage is input; and first transistor elements installed between the power supply line and the gate line, and wherein the first current source is switched between a state, in which gate of each first transistor element is connected to the output of the first error amplifier, and OFF state.