A motor starter for operating an electric motor connected to a multiphase power supply includes a semiconductor switch arranged in a current-carrying phase of the multiphase power supply, and an electromechanical switch arranged in parallel relation to the semiconductor switch in the current-carrying phase. The electromechanical switch includes a movable switching piece configured tiltable to reduce a current gradient in the semiconductor switch.

A motor starter for operating an electric motor connected to a multiphase power supply includes a semiconductor switch arranged in a current-carrying phase of the multiphase power supply, and an electromechanical switch arranged in parallel relation to the semiconductor switch in the current-carrying phase. The electromechanical switch includes a movable switching piece configured tiltable to reduce a current gradient in the semiconductor switch.

The invention utilizes an asymmetric magnetic field caused by a mechanism design between a motor rotor and a stator to induce a BEMF, and discloses a method for starting a fixed rotation direction of single-phase sensorless DC brushless motor, including: power-on starting a motor control circuit; if the motor not in the rotating state before starting the excitation, executing a static starting procedure; then, if the motor rotation direction conforming to the predetermined direction, executing a normal driving procedure; otherwise, executing a static starting procedure. The static starting procedure, after of static starting by discharging remnant energy of the motor, achieves the purpose of star-up by performing the steps of first phase excitation, stop excitation, and strong second phase excitation. In the normal driving procedure, the slopes of BEMF signal of the first phase or the second phase is taken out periodically to detect the motor rotation direction.

A thyristor starter is configured to accelerate a synchronous machine from a stop state to a predetermined rotation speed by sequentially performing a first mode of performing commutation of an inverter by intermittently setting DC output current of a converter to zero and a second mode of performing commutation of the inverter by induced voltage of the synchronous machine. In a first case in which a first synchronous machine having a first inductance is started, a switching rotation speed for switching from the first mode to the second mode is set to a higher rotation speed, compared with a second case in which a second synchronous machine having a second inductance larger than the first inductance is started.

Unique systems, methods, techniques and apparatuses of motor starters are disclosed. One exemplary embodiment is a synchronous machine including a plurality of stator phase windings, a rotor, a motor starter, and a controller. The motor starter includes a plurality of wye semiconductor switches and a plurality of delta semiconductor switches. The controller is structured to operate the plurality of wye semiconductor switches and the plurality of delta semiconductor switches so as to couple the plurality of stator phase windings in a delta configuration while an angular speed of the rotor is less than a synchronous speed, and structured to operate the plurality of wye semiconductor switches and the plurality of delta semiconductor switches so as to couple the plurality of stator phase windings in a wye configuration in response to the angular speed of the rotor being equal to the synchronous speed.

A method is for a machine having an alternating current (AC) power source with a first side (L1) and a second side (L2), two or more pairs of power switches, and one or more windings. The method comprises closing one pair of power switches by a control circuit to cause current to flow from a first side of the AC power source, through the one or more windings, and to the second side of the AC power source and closing another pair of power switches by the control circuit to cause current to flow from the second side of the AC power source, through the one or more windings, and to the first side of the AC power source.

A motor drive apparatus includes an AC stabilized power supply configured to convert AC voltage of a commercial AC power source into input power supply voltage according to a received voltage command value and output the input power supply voltage, a converter configured to convert the input power supply voltage into DC voltage and output the DC voltage to a DC link, an inverter configured to convert the DC voltage at the DC link into AC voltage for driving a motor, and an input power supply voltage control unit configured to control the input power supply voltage that is output by the AC stabilized power supply.

A motor drive apparatus includes an AC stabilized power supply configured to convert AC voltage of a commercial AC power source into input power supply voltage according to a received voltage command value and output the input power supply voltage, a converter configured to convert the input power supply voltage into DC voltage and output the DC voltage to a DC link, an inverter configured to convert the DC voltage at the DC link into AC voltage for driving a motor, and an input power supply voltage control unit configured to control the input power supply voltage that is output by the AC stabilized power supply.

Provided is a wire connecting structure of coils of a three-phase motor, a wire connecting method and three-phase motor, which is capable of reducing a size of a short circuit terminal for a neutral point. The wire connecting structure is a wire connecting structure of coils which are wound to each salient-pole in a three-phase motor having respective salient-pole of a U phase, a V phase and a W phase, the coils of the salient-poles belonging to any two phases among the U phase, the V phase and the W phase are formed by a single continuous first conducting wire, and the coil of the salient-pole belonging to the rest one phase is formed by a single continuous second conducting wire.

Provided is a wire connecting structure of coils of a three-phase motor, a wire connecting method and three-phase motor, which is capable of reducing a size of a short circuit terminal for a neutral point. The wire connecting structure is a wire connecting structure of coils which are wound to each salient-pole in a three-phase motor having respective salient-pole of a U phase, a V phase and a W phase, the coils of the salient-poles belonging to any two phases among the U phase, the V phase and the W phase are formed by a single continuous first conducting wire, and the coil of the salient-pole belonging to the rest one phase is formed by a single continuous second conducting wire.