Systems and methods are described for controlling an electric motor. An exemplary system may include a torque detector configured to detect an output torque of the electric motor. The system may also include a controller configured to control a voltage source to apply a predetermined voltage to drive the electric motor and determine an operating table containing a plurality of operating points. The controller may select an operating current value and generate a plurality of current commands. The controller may also apply each of the plurality of current commands to drive the electric motor and determine an output torque generated by the electric motor. The controller may further determine a target current command that generates a maximum output torque. In addition, the controller may determine an operating point of the operating table based on the target current command. Moreover, the controller may control the electric motor using the operating table.

For operating multi-axis drive assemblies more reliably even in a field weakening range, a current conversion device is proposed which includes a voltage-source DC link, a plurality of inverters having each a DC input side connected to the voltage-source DC link and AC output-side terminals for connection to an electric motor, and a control device configured to short-circuit each of the inverters. A measurement device measures an electrical variable at each of the inverters. The control device determines based on the measured electrical variables independently for each of the inverters directly or indirectly whether a particular inverter is feeding energy into the voltage-source DC link, and short-circuits, when this is the case, the particular inverter independently of the other inverters. A corresponding operating method is also disclosed.

In some embodiments, a system of controlling an induction electric motor, includes a command voltage output unit for generating a command voltage for operating an inverter according to a command speed and outputting the generated command voltage to the inverter; a control unit for controlling the command voltage output unit such that the command voltage output to the inverter is compared with an operation limiting voltage and the command voltage is corrected to fall within the operation limiting voltage; and the inverter for controlling the induction electric motor depending on the corrected command voltage. Thus, it is possible to precisely control the induction electric motor even in a high speed operation region by regulating the magnitude of the command voltage applied to the induction electric motor by means of dynamic modulation strategies without the magnetic flux controller.

An inverter electrically operatively connected to an electric machine and in communication with a controller is described. The inverter is electrically connected to a high-voltage DC power bus. A method for controlling the multi-phase inverter circuit includes monitoring, via the controller, a rotational speed of the electric machine during operation of the inverter in an over-modulation mode. The inverter is commanded to operate in a linear modulation mode when the rotational speed is within a speed range associated with objectionable audible noise generated by operating the electric machine in the over-modulation mode.

A railway vehicle comprises a traction system including an asynchronous electric motor or a synchronous electric DC motor operable by an inverter electronic drive system. The vehicle further comprises an electronic control unit coupled to the traction system and configured to receive signals/data/commands indicative of operating conditions of the vehicle and of the traction system and to determine, based on the received signals/data/commands, the occurrence of a coasting condition of the vehicle and the occurrence of an exit condition from the coasting condition of the vehicle. If a coasting condition of the vehicle occurs, the electronic drive system is controlled to cause the electric motor to undergo magnetic flux changes. If an exit condition from the coasting condition occurs, and depending whether the electronic drive system is on or off, the electronic drive system is controlled to increase torque of the electric motor or to reduce magnetic flux reduction.

An apparatus for controlling an AC power supply for an electric motor, said AC power supply being derived from a DC voltage. The apparatus comprises a comparer configured to provide a comparison of a modulation index of a motor control signal with a reference value. This current data provider is configured to provide current data based on a torque demand signal; a speed signal indicating the speed of rotation of the AC motor; and an indication of the DC voltage modified on the comparison for control of the motor control signal which is based on the motor current data.

An object is to provide a permanent magnet motor controller capable of suppressing the rotary bending vibration that occurs in the permanent magnet motor effectively with simple configuration. A permanent magnet motor controller uses the dq coordinate conversion. A dq target current setting part adds the current component (i*.sub.da) that cancels the magnetic attractive force acting in the radial direction of the rotational shaft of the rotor of the permanent magnet motor to the d-axis target current value, whereby the eccentricity of the rotational shaft of the rotor is reduced.

A controller of a power tool is configured to, based on a sampled current of a motor of the power tool, output control signals that change with a change of a position of a rotor of the motor to control a drive circuit of the power tool such that an input voltage and/or a current of the motor changes approximately in a sine wave.

A method for controlling an asynchronous electrical motor, implemented in a processing unit associated with a power converter connected to the electrical motor, the method including an identification phase, which includes generating a speed trajectory in input of a control law of the motor in order to make the speed reference take several determined successive values, for each value taken by the speed reference, determining the voltage at the terminals of the electrical motor, for each value taken by the speed reference, determining and storing the flux value for which the voltage at the terminals of the electrical motor is equal to a determined threshold value.

Disclosed is a vector flux weakening control method for vector flux weakening for a vehicle permanent magnet synchronous motor, which includes a current closed-loop adjuster, a modulation ratio deviation calculator, a current command angle compensator, a current angle preset processor, a current command angle limiting comparator and a current given vector corrector. The adjusting direction of the present disclosure is always a flux weakening direction, and instability caused by repeated adjustment will not occur; by introducing dq current while performing correction, the pressure against voltage saturation can be shared to both d-axis and q-axis current, so as to avoid excessive output torque deviation caused by excessive adjustment of a single-axis current; the influence of the flux weakening control link on the output torque of the drive system can be minimized as much possible while ensuring the safety of the drive system.