The object of the invention is a method of controlling a permanent-magnet synchronous or synchro-reluctant three-phase rotary machine (4), comprising the following steps: measuring a current (i.sub.A, i.sub.B, i.sub.C) flowing through each phase of a stator of rotary machine (4); first calculating, by use of a single proportional-integral controller, a switching control signal for controlling an inverter (10), according to each measured current (i.sub.A, i.sub.B, i.sub.C), and of a target value (T.sub.ref) of a mechanical torque provided by the rotary machine (4) or of a target value of an angular speed of a rotor of rotary machine (4) in relation to the stator wherein the inverter (10) is configured to convey electrical energy between a continuous electrical energy source (8) and each phase of the stator of rotary machine (4); and
controlling the inverter (10) by use of the calculated switching control signal.

The object of the invention is a method of controlling a permanent-magnet synchronous or synchro-reluctant three-phase rotary machine (4), comprising the following steps: measuring a current (i.sub.A, i.sub.B, i.sub.C) flowing through each phase of a stator of rotary machine (4); first calculating, by use of a single proportional-integral controller, a switching control signal for controlling an inverter (10), according to each measured current (i.sub.A, i.sub.B, i.sub.C), and of a target value (T.sub.ref) of a mechanical torque provided by the rotary machine (4) or of a target value of an angular speed of a rotor of rotary machine (4) in relation to the stator wherein the inverter (10) is configured to convey electrical energy between a continuous electrical energy source (8) and each phase of the stator of rotary machine (4); and
controlling the inverter (10) by use of the calculated switching control signal.

A system contains a double fed induction machine having a stator and a rotor, a fly wheel coupled to the rotor, and a control device for providing a rotor voltage and a rotor current to the rotor. The control device is connected to the rotor and the stator and is capable of generating the rotor voltage and rotor current in response to an electrical signal that is applied to the stator. The control device has a multilevel converter and a control unit for controlling the multilevel converter.

A system contains a double fed induction machine having a stator and a rotor, a fly wheel coupled to the rotor, and a control device for providing a rotor voltage and a rotor current to the rotor. The control device is connected to the rotor and the stator and is capable of generating the rotor voltage and rotor current in response to an electrical signal that is applied to the stator. The control device has a multilevel converter and a control unit for controlling the multilevel converter.

A control device for an electric motor includes an inverter circuit; and a control circuit that finds a voltage command value such that the d-axis current and the q-axis current approach a d-axis current command value and a q-axis current command value, and turns the plurality of switching elements on and off by using a drive signal in accordance with a result of comparison between the voltage command value and a carrier wave. The control circuit corrects the voltage command value by using a polarity of the alternating current during dead time, and causes the d-axis current command value in a certain length of time before and after the alternating current reaches zero to be greater than the d-axis current command value in a length of time other than the certain length of time.

A control device for an electric motor includes an inverter circuit; and a control circuit that finds a voltage command value such that the d-axis current and the q-axis current approach a d-axis current command value and a q-axis current command value, and turns the plurality of switching elements on and off by using a drive signal in accordance with a result of comparison between the voltage command value and a carrier wave. The control circuit corrects the voltage command value by using a polarity of the alternating current during dead time, and causes the d-axis current command value in a certain length of time before and after the alternating current reaches zero to be greater than the d-axis current command value in a length of time other than the certain length of time.

A rotation detector includes a motor, a current detector and a hardware processor. The motor includes coils of two or more phases and a rotor. The current detector detects currents flowing in coils of at least two phases among the coils of two or more phases. The hardware processor estimates an initial position of the rotor based on current values of the currents detected by the current detector to start the motor, controls an energization pattern on the phases to rotate and start the motor based on the estimated initial position, and determines whether the rotor stops or is rotating before completing the estimation of the initial position.

A rotation detector includes a motor, a current detector and a hardware processor. The motor includes coils of two or more phases and a rotor. The current detector detects currents flowing in coils of at least two phases among the coils of two or more phases. The hardware processor estimates an initial position of the rotor based on current values of the currents detected by the current detector to start the motor, controls an energization pattern on the phases to rotate and start the motor based on the estimated initial position, and determines whether the rotor stops or is rotating before completing the estimation of the initial position.

In a control device for an AC rotary machine, having an angle detector for detecting an electrical angle of the AC rotary machine, a detection error produced by the angle detector due to a noise magnetic field generated by a multi-phase alternating current flowing through an inverter connection unit is corrected using a correction signal having a phase and an amplitude that are determined in accordance with a relative positional relationship between the inverter connection unit and the angle detector and a current vector of the multi-phase alternating current, whereupon an inverter is controlled on the basis of the corrected electrical angle. As a result, a simple, low-cost control device for an AC rotary machine with which an angular position of a rotor can be detected with a high degree of precision is obtained.

In a control device for an AC rotary machine, having an angle detector for detecting an electrical angle of the AC rotary machine, a detection error produced by the angle detector due to a noise magnetic field generated by a multi-phase alternating current flowing through an inverter connection unit is corrected using a correction signal having a phase and an amplitude that are determined in accordance with a relative positional relationship between the inverter connection unit and the angle detector and a current vector of the multi-phase alternating current, whereupon an inverter is controlled on the basis of the corrected electrical angle. As a result, a simple, low-cost control device for an AC rotary machine with which an angular position of a rotor can be detected with a high degree of precision is obtained.