Protection devices prevent damage to synchronous generators during loss-of-field events. In various embodiments, a first protective element is associated with a first protection zone to protect a generator from a loss-of-field event at full load. A second protective element is associated with a second protection zone to prevent thermal overload during underexcited operation of the generator and to protect from loss-of-filed at light load. A third protective element associated with a third protection zone limits operation of the generator within the generator's specific steady-state stability limits. A fourth protective element is associated with a fourth protection zone to provide an alarm prior to operation of the second protective element. In various embodiments, characteristics and limits of each of the protective elements are defined in the same plane (specifically, the P-Q plane) to simplify settings and allow for visualization of the element characteristics and the generator capability curve at one or more temperatures or cooling capacities.

Technical solutions are described for controlling operation of an inverter to manage voltage upon a direct current (DC) bus and regenerative power (current) provided to a battery. A control system and method are provided to control operation of an electric machine using a controller. More specifically, the controller is configured to calculate a current-based torque limit to satisfy a regenerative current limit, and a voltage-based torque limit to satisfy a voltage limit constraint of the DC bus. The controller is configured to calculate a torque limit to satisfy the regenerative current and voltage limits of the DC bus, and to command a plurality of switches within the inverter to generate a direct-axis current from the electric machine corresponding to a torque demand and according to the torque limit. The proposed system and method provide for motor current that exceed a demagnetizing current limit of the electric machine.

An electronic device, in particular an alternator regulator, comprising a power stage to be connected to an inductive load, in particular to an alternator inductor, comprising at least one first pair of power transistors connected to a terminal of a DC bus, and a control circuit for said transistors, the transistors being disposed in parallel between said terminal of the DC bus and a first output to be connected to the load, at least one flyback diode connecting the opposite terminal of the DC bus to the first output, the control circuit being designed to generate a pulsed control signal for regulating the current in the load and for detecting a failure of one of the transistors, the control circuit being designed, during normal operation, to send the control signal to one of the transistors of the first pair, while maintaining the other transistor of said pair in an off-state.

A de-exciting system for dissipating energy from an inductive circuit that comprises at least one coil adapted to be attached to said inductive circuit and comprising a series connection of a discharge resistor and a unidirectional discharge switching element; a unidirectional bypass switching element that is connected in parallel to the discharge resistor such that, when the de-exciting system is attached to the inductive circuit and both the discharge switching element and the bypass switching element are in a conducting state, a closed conducting path comprising the coil, the discharge switching element, and the bypass switching element is formed; and a control device configured to, in a first de-excitation phase, switch both the discharge switching element and the bypass switching element into a conducting state, and in a second de-excitation phase, switch the bypass switching element into a non-conducting state, while keeping the discharge switching element in the conducting state.

A de-exciting system for dissipating energy from an inductive circuit that comprises at least one coil adapted to be attached to said inductive circuit and comprising a series connection of a discharge resistor and a unidirectional discharge switching element; a unidirectional bypass switching element that is connected in parallel to the discharge resistor such that, when the de-exciting system is attached to the inductive circuit and both the discharge switching element and the bypass switching element are in a conducting state, a closed conducting path comprising the coil, the discharge switching element, and the bypass switching element is formed; and a control device configured to, in a first de-excitation phase, switch both the discharge switching element and the bypass switching element into a conducting state, and in a second de-excitation phase, switch the bypass switching element into a non-conducting state, while keeping the discharge switching element in the conducting state.

A control method and a switching device are provided for a separately excited synchronous machine as a drive in a hybrid or electric vehicle. The switching device converts and/or distributes electrical energy within the vehicle, in particular the hybrid or electric vehicle, wherein an asymmetric full bridge is provided, in the bridge branch of which a rotor of an SSM is arranged. Switches are provided in the asymmetric full bridge in order to provide a pulse width modulation corresponding to a desired motor rotational speed and power of the SSM. The device is characterized in that it has a short-circuit branch extending in parallel with the bridge branch of the asymmetric full bridge, by which short-circuit branch the rotor of the SSM is able to be short-circuited.

A permanent magnet synchronous motor includes a stator, a rotor rotatable relative to the stator, and a magnetic structure with a low coercive force magnet and a high coercive force magnet that are arranged magnetically in series with respect to each other to define a pole-pair of the permanent magnet synchronous motor. A magnetization level of the low coercive force magnet is changeable by a stator current pulse such that a stator magnetomotive force at a rated current is equal to or larger than a product of a magnetic field strength for fully magnetizing the low coercive force magnet and a thickness of the low coercive force magnet.

Technical solutions are described for controlling operation of an inverter to manage voltage upon a direct current (DC) bus and regenerative power (current) provided to a battery. A control system and method are provided to control operation of an electric machine using a controller. More specifically, the controller is configured to calculate a current-based torque limit to satisfy a regenerative current limit, and a voltage-based torque limit to satisfy a voltage limit constraint of the DC bus. The controller is configured to calculate a torque limit to satisfy the regenerative current and voltage limits of the DC bus, and to command a plurality of switches within the inverter to generate a direct-axis current from the electric machine corresponding to a torque demand and according to the torque limit. The proposed system and method provide for motor current that exceed a demagnetizing current limit of the electric machine.

A method for operating a permanent magnet electric machine of an engine includes determining a fault condition of the permanent magnet electric machine; and reducing a magnetism of one or more permanent magnets of the permanent magnet electric machine by increasing a temperature of the one or more permanent magnets in response to determining the fault condition of the permanent magnet electric machine.

A method for operating a permanent magnet electric machine of an engine includes determining a fault condition of the permanent magnet electric machine; and reducing a magnetism of one or more permanent magnets of the permanent magnet electric machine by increasing a temperature of the one or more permanent magnets in response to determining the fault condition of the permanent magnet electric machine.