Abstract: A method for controlling circuitry of a softstarter arrangement to operate an electric motor for driving a pump is provided, wherein the softstarter circuitry electrically connects the motor to electric mains. The method includes: (i) controlling the circuitry of the softstarter arrangement to accelerate the motor up to full speed in a forward direction; (ii) controlling the circuitry of the softstarter arrangement to decelerate the motor when the motor has run at full speed in the forward direction for a first period of time; (iii) controlling the circuitry of the softstarter arrangement to accelerate the motor up a specified speed in a reverse direction; (iv) controlling the circuitry of the softstarter arrangement to decelerate the motor when the motor has run at the specified speed in the reverse direction for a second period of time; and (v) repeating the steps (i)-(iv) one or more times.

Abstract: A method for controlling circuitry of a softstarter arrangement to operate an electric motor for driving a pump is provided, wherein the softstarter circuitry electrically connects the motor to electric mains. The method includes: (i) controlling the circuitry of the softstarter arrangement to accelerate the motor up to full speed in a forward direction; (ii) controlling the circuitry of the softstarter arrangement to decelerate the motor when the motor has run at full speed in the forward direction for a first period of time; (iii) controlling the circuitry of the softstarter arrangement to accelerate the motor up a specified speed in a reverse direction; (iv) controlling the circuitry of the softstarter arrangement to decelerate the motor when the motor has run at the specified speed in the reverse direction for a second period of time; and (v) repeating the steps (i)-(iv) one or more times.

Abstract: A softstarter for starting and stopping an asynchronous motor having three phases, including two pairs of semiconductor devices of the type turning off at zero-crossing of the current therethrough, wherein each of the two pairs of semiconductor devices is connected in anti-parallel, and the first pair of the semiconductor devices is adapted to control the voltage of one of the phases of the motor and the second pair of the semiconductor devices being adapted to control the voltage of another of the phases of the motor, a DC reducing unit associated with the two pairs of semiconductor devices, a first voltage measuring unit for measuring voltages across the two pairs of semiconductor devices, and a first zero-crossing detecting unit configured for detecting zero-crossings of the measured voltages across the two pairs of semiconductor devices and providing zero-crossing signals to the DC reducing unit.

Abstract: A softstarter for starting and stopping an asynchronous motor having three phases, including two pairs of semiconductor devices of the type turning off at zero-crossing of the current therethrough, wherein each of the two pairs of semiconductor devices is connected in anti-parallel, and the first pair of the semiconductor devices is adapted to control the voltage of one of the phases of the motor and the second pair of the semiconductor devices being adapted to control the voltage of another of the phases of the motor, a DC reducing unit associated with the two pairs of semiconductor devices, a first voltage measuring unit for measuring voltages across the two pairs of semiconductor devices, and a first zero-crossing detecting unit configured for detecting zero-crossings of the measured voltages across the two pairs of semiconductor devices and providing zero-crossing signals to the DC reducing unit.

Abstract: A method for controlling an electric motor with a softstarter. A softstarter device for control of electric motors. Motor torque is controlled in dependence of a torque error signal, based on a calculated difference between the motor torque and a reference torque value, so that the motor torque displays a rate of change with respect to time, during a stopping or starting time interval, that is adapted to follow a rate of change of the reference torque value, with respect to time, that varies between at least a first part of the time interval and a second part of the time interval, and thereby changing the speed of the motor. A system includes an electric motor, a device driven by the electric motor and a softstarter device for controlling the electric motor. A computer program product includes a computer readable medium and a computer program recorded thereon.

Abstract: A method for controlling an electric motor with a softstarter. A softstarter device for control of electric motors. Motor torque is controlled in dependence of a torque error signal, based on a calculated difference between the motor torque and a reference torque value, so that the motor torque displays a rate of change with respect to time, during a stopping or starting time interval, that is adapted to follow a rate of change of the reference torque value, with respect to time, that varies between at least a first part of the time interval and a second part of the time interval, and thereby changing the speed of the motor. A system includes an electric motor, a device driven by the electric motor and a softstarter device for controlling the electric motor. A computer program product includes a computer readable medium and a computer program recorded thereon.