A stepless motor driving circuit provides a sinusoidal shaped chopping signal for driving a motor. The driving circuit has: a switch circuit having an input which receives a rectified signal rectified from a sinusoidal AC signal and having a first output and a second output where the motor is coupled between; a synchronizing signal generating circuit which generates a synchronizing signal relating to the sinusoidal AC signal; and a switch driving circuit which selects and chops at least one switch in the switch circuit according to the synchronizing signal, and to form the sinusoidal shaped chopping signal which is corresponding to the sinusoidal AC signal.

A drive device that includes a rotating-field rotary electric machine; and an inverter that drives the rotary electric machine, wherein: the rotary electric machine includes a stator core, and a coil wound on the stator core; the coil includes a first coil and a second coil electrically insulated from each other; and the inverter includes a first inverter circuit that supplies AC power to the first coil, and a second inverter circuit that supplies AC power to the second coil.

Provided is a switch drive circuit that drives a plurality of switches mutually connected in parallel including a charge unit allowing charge current to flow to the gate of the switch; an off switch connecting between the gate of the switch and the ground; a detection unit detecting whether charge state of the gate of the switch is in a predetermined state; and a changeover unit that changes a state of off switches when the charge units allow the charge current to flow to the gate. The changeover unit changes the state of the off switches to be ON when detection units do not detect the charge state of the gate being in the predetermined state, and to change the state of the off switches to be OFF when detection units detect the charge state of the gate being in the predetermined state.

A drive circuit for an electric motor includes a first filter, a rectifier, an inverter, and a line contactor. The first filter is configured to be coupled to an AC source and produces a filtered line frequency AC signal. The rectifier is coupled to the filter and produces a DC signal from the filtered line frequency AC signal. The inverter is coupled to the rectifier and produces an AC signal on an output node of the inverter. The AC signal is supplied to the electric motor to energize its stator windings. The line contactor is coupled between an output node of the first filter and the output node of the inverter. The line contactor supplies the output node of the inverter directly with the filtered line frequency AC signal to energize the stator windings when the inverter is disabled.

A method for driving an electric motor includes providing two controllers for driving the electric motor. The two controllers use different control methods to drive the electric motor. The method further includes selecting a first controller of the controllers as a primary controller to drive the electric motor and a second controller of the controllers as a secondary controller, monitoring a control of the electric motor, and switching the control of the electric motor from the primary controller to the secondary controller if an error condition is detected in the control of the electric motor.

A method for controlling a motor includes obtaining a present electrical parameter of a battery, calculating a compensation amount of a control signal of the motor according to the present electrical parameter, and modifying the control signal according to the compensation amount.

A method for measuring a line resistance R.sub.L (7) and determining control line (16) faults in a hazard warning and control system. The control lines (16) connect a control device (20) to an actuator (10) using an actuation voltage U.sub.A in the case of an event and supplies the actuator (10) with a monitoring voltage U.sub.M in the case of a monitoring process using a monitoring module (21). Furthermore, the control device (20) has a constant current sink (6), which can be activated by a microcontroller (1), and a switchover device (5). In order to determine the line resistance R.sub.L (7), a constant voltage supply is provided in a measurement time interval t.sub.M by an energy store (9) integrated into the monitoring module (21) and is fed back to the control device (20), and the switchover device (5) deactivates the monitoring voltage U.sub.M supply from the control device (20) to the actuator (10) during the entire measurement time interval t.sub.M.

A wind power generation system including a doubly fed induction generator (DFIG) of a wind turbine is presented. The DFIG includes a rotor and a stator, a rotor-side conversion unit coupled to the rotor, a direct current (DC) link, and at least one line-side conversion unit coupled to the rotor-side conversion unit via the DC link and coupled to the stator of the DFIG. The at least one line-side conversion unit includes exactly one first converter, high frequency transformers, and second converters, where each of the second converters is coupled to the first converter via a respective high frequency transformer, and inverters, where each of the inverters is coupled to a respective second converter and includes an alternative current (AC) phase terminal.