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.

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 motor starter includes a control unit and a first current path, via which energy can be supplied to a downstream electrical motor. The first current path includes a semiconductor switch and an electromechanical switch element, the semiconductor switch and the switch element being connected in series. In order to provide a cost-effective, safe motor starter, according to an embodiment of the invention the control unit is designed such that, in order to produce an energy supply via the first current path in a first step, it ensures that the voltage currently connected via the switch element, in respect of a previous opening of the switch element, lies below the allowable maximum blocking voltage of the semiconductor switch. Subsequently in a second step, the switch element first closes and then switches the semiconductor switch to be conductive.

A motor starter includes a control unit and a first current path, via which energy can be supplied to a downstream electrical motor. The first current path includes a semiconductor switch and an electromechanical switch element, the semiconductor switch and the switch element being connected in series. In order to provide a cost-effective, safe motor starter, according to an embodiment of the invention the control unit is designed such that, in order to produce an energy supply via the first current path in a first step, it ensures that the voltage currently connected via the switch element, in respect of a previous opening of the switch element, lies below the allowable maximum blocking voltage of the semiconductor switch. Subsequently in a second step, the switch element first closes and then switches the semiconductor switch to be conductive.

A device (1) for starting a motor (4) for alternating current, in particular for a compressor (5), wherein the motor (4) has at least one feed line (3) for the electrical power supply. The device comprises an actuator element (10) for limiting the current in the feed line (3), a switching element (16) for bypassing the actuator element (10), a current-monitoring element (15) for monitoring the current in the feed line (3), and a controller (18) for controlling the switching element (16). The actuator element (10) comprises at least a first start-up element (11) and a second start-up element (12) as well as a switch-over element (14) for switching over between the at least first and second start-up elements (11, 12).

A device (1) for starting a motor (4) for alternating current, in particular for a compressor (5), wherein the motor (4) has at least one feed line (3) for the electrical power supply. The device comprises an actuator element (10) for limiting the current in the feed line (3), a switching element (16) for bypassing the actuator element (10), a current-monitoring element (15) for monitoring the current in the feed line (3), and a controller (18) for controlling the switching element (16). The actuator element (10) comprises at least a first start-up element (11) and a second start-up element (12) as well as a switch-over element (14) for switching over between the at least first and second start-up elements (11, 12).

A system and method to detect an onset of motor rotation for an induction motor. The system and method involves monitoring a power supplied to a motor via a sensor, determining a power quantity based on the power monitored by the sensor, detecting an envelope of the power quantity, detecting an onset of rotation of the motor when an amplitude of the envelope has increased, and inhibiting power flow to the motor when the onset of rotation does not occur within a predetermined time period or logging a first time period of the detected onset of rotation of the motor for use in monitoring the condition of the motor. The power quantity can be a current vector magnitude or an instantaneous power corresponding to the supplied power.

A system and method to detect an onset of motor rotation for an induction motor. The system and method involves monitoring a power supplied to a motor via a sensor, determining a power quantity based on the power monitored by the sensor, detecting an envelope of the power quantity, detecting an onset of rotation of the motor when an amplitude of the envelope has increased, and inhibiting power flow to the motor when the onset of rotation does not occur within a predetermined time period or logging a first time period of the detected onset of rotation of the motor for use in monitoring the condition of the motor. The power quantity can be a current vector magnitude or an instantaneous power corresponding to the supplied power.

A method controls the current output of a battery for driving a rail vehicle. A battery actual current I.sub.bat,ist passes via a converter to an asynchronous motor, being a drive for the vehicle. The battery actual current I.sub.bat,ist is set by control circuits as a function of a feedforward control torque M.sub.ff and a specified torque M.sub.tf. The feedforward control torque M.sub.ff is calculated using a transfer function H.sub.sys(z), which maps the torque setpoint value M.sub.soll onto the battery actual current I.sub.bat,ist as follows: I.sub.bat(z) H.sub.sys(z) M.sub.soll(z). Accordingly, a zero-point z=znmp, which lies outside the unit circle, is determined by the transfer function H.sub.sys(z). The feedforward control torque M.sub.ff is calculated as follows: M.sub.ff(z) I.sub.bat,neu(z)/(H.sub.sys(z) z) where: I.sub.bat,neu(z)=I.sub.bat,ideal(z) I.sub.bat,ideal(z=znmp) where: I.sub.bat,neu[n]=I.sub.bat,ideal[n] for all n>0, so that pole point/zero point cancellation is reached by z=znmp at the battery ideal current.

A PCB motor controller comprises relays mounted on a PCB and interconnected to power traces in or on the PCB to receive incoming three-phase power and to output three-phase power to a motor. Control power traces in or on the PCB connect the relays to control circuitry, also mounted on the PCB. A power supply is mounted on the PCB and connected to the control circuitry to provide power for its operation and for switching of the relays. The relays are switched in accordance with a point-on-wave (POW) switching scheme, allowing for the use or relays and the PCB, which may not otherwise be suitable for motor control applications.