A kinetic energy recovery system with flywheel includes a flywheel doubly-fed electric machine, an electric motor, a drive circuit and a controller. The flywheel doubly-fed electric machine has a primary side coil and a secondary side coil. The electric motor has a phase coil connected in series with the primary side coil. The drive circuit has an AC/DC circuit and a DC/AC circuit, wherein the AC end of the AC/DC circuit is coupled to the primary side coil; the AC end of the DC/AC circuit is coupled to the secondary side coil. The controller is configured to manipulate a frequency and a phase of output voltage and output current of the secondary side coil, thereby controlling the frequency and phase of a voltage and a current output from the primary side coil, thereby recovering a kinetic energy of the electric motor or providing the kinetic energy to the electric motor.

A motor system is disclosed comprising: an electrical conductor in the form of a coil or winding; an electrical insulator insulating the electrical conductor; a discharge sensor arranged and configured to measure a parameter indicative of an electrical current in the insulator; and a voltage controller for controlling a voltage signal applied to the electrical conductor based on a value of the parameter measured by the discharge sensor.

A motor system is disclosed comprising: an electrical conductor in the form of a coil or winding; an electrical insulator insulating the electrical conductor; a discharge sensor arranged and configured to measure a parameter indicative of an electrical current in the insulator; and a voltage controller for controlling a voltage signal applied to the electrical conductor based on a value of the parameter measured by the discharge sensor.

An aspect of the disclosed invention calculates a value of an inductance of a synchronous motor whose characteristic is unclear while suppressing a failure of the synchronous motor. A motor driving device according to an embodiment of the disclosed invention comprises: a motor; an inverter for supplying an alternating voltage to the motor; a current meter for measuring an introduced current flowing through the motor on the basis of the alternating voltage; and a control unit for controlling the inverter to change the size of the alternating voltage in stages, and calculating an inductance of the motor on the basis of the introduced current measured by the current meter.

An aspect of the disclosed invention calculates a value of an inductance of a synchronous motor whose characteristic is unclear while suppressing a failure of the synchronous motor. A motor driving device according to an embodiment of the disclosed invention comprises: a motor; an inverter for supplying an alternating voltage to the motor; a current meter for measuring an introduced current flowing through the motor on the basis of the alternating voltage; and a control unit for controlling the inverter to change the size of the alternating voltage in stages, and calculating an inductance of the motor on the basis of the introduced current measured by the current meter.

A rotary electric machine is equipped with a stator and a rotor. The rotor has a d-axis magnetic circuit that is produced by a magnetomotive force of a field winding, and magnet magnetic circuits that are produced by a magnetic force of permanent magnets. The d-axis magnetic circuit and a q-axis magnetic circuit have at least a part thereof that is common to both. The permeance of the d-axis magnetic circuit is smaller than the permeance of the q-axis magnetic circuit, when a load is being applied to the rotor. A control apparatus of the rotary electric machine has a switching circuit that controls the field current in the field winding, and a control section that makes the switching frequency of the switching circuit become higher when the field current is above a threshold value than when the field current is less than or equal to the threshold value.

According to one embodiment, a control system includes a chopper, a short-circuit unit, a voltage detector circuit, and a controller. The chopper reduces a direct current voltage between a converter connected to a stator in a wound induction machine and an inverter connected to a rotor in the wound induction machine. The short-circuit unit shorts a wire used for connection between the rotor and the inverter and the voltage detector circuit is to detect the direct current voltage. The controller causes driving the chopper and, at the same time, outputting from the inverter an alternating current over which a direct current component is superimposed when a voltage value exceeds a first predetermined value, and causes driving the short-circuit unit and, at the same time, halting the inverter when the voltage value exceeds a second predetermined value.

According to one embodiment, a control system includes a chopper, a short-circuit unit, a voltage detector circuit, and a controller. The chopper reduces a direct current voltage between a converter connected to a stator in a wound induction machine and an inverter connected to a rotor in the wound induction machine. The short-circuit unit shorts a wire used for connection between the rotor and the inverter and the voltage detector circuit is to detect the direct current voltage. The controller causes driving the chopper and, at the same time, outputting from the inverter an alternating current over which a direct current component is superimposed when a voltage value exceeds a first predetermined value, and causes driving the short-circuit unit and, at the same time, halting the inverter when the voltage value exceeds a second predetermined value.

A motor system is disclosed comprising: an electrical conductor in the form of a coil or winding; an electrical insulator insulating the electrical conductor; a discharge sensor arranged and configured to measure a parameter indicative of an electrical current in the insulator; and a voltage controller for controlling a voltage signal applied to the electrical conductor based on a value of the parameter measured by the discharge sensor.

A motor system is disclosed comprising: an electrical conductor in the form of a coil or winding; an electrical insulator insulating the electrical conductor; a discharge sensor arranged and configured to measure a parameter indicative of an electrical current in the insulator; and a voltage controller for controlling a voltage signal applied to the electrical conductor based on a value of the parameter measured by the discharge sensor.