Systems and techniques detecting a reverse current are disclosed. An apparatus comprises a switching circuit coupled to a load and a reference node. The switching circuit may be capable of conducting a reverse current from the reference node to the load when a voltage at the load is lower than a voltage at the reference node. A voltage source has a first terminal coupled to the load, a second terminal configured to follow a voltage at the load, and produces a voltage proportional to a voltage drop across the switching circuit. A comparator circuit is coupled to compare a voltage at the second terminal of the voltage source to the voltage at the reference node and configured to indicate when the reverse current has a magnitude greater than a predetermined threshold.

The present subject matter is directed to a system and method for improving speed control of a pitch drive system of a wind turbine. In one embodiment, the pitch drive system includes a direct current (DC) motor having an armature and a series-field winding, a battery assembly having a positive terminal and a negative terminal, and a current-controlling device configured in series between the positive terminal of the battery assembly and the series-field winding. The battery assembly is configured to supply power to the pitch drive system and the current-controlling device is configured to supply current to the series-field winding so as to ensure a field flux does not equal zero. Thus, the current-controlling device has the effect of limiting the maximum speed of the DC motor.

The present subject matter is directed to a system and method for improving speed control of a pitch drive system of a wind turbine. In one embodiment, the pitch drive system includes a direct current (DC) motor having an armature and a series-field winding, a battery assembly having a positive terminal and a negative terminal, and a current-controlling device configured in series between the positive terminal of the battery assembly and the series-field winding. The battery assembly is configured to supply power to the pitch drive system and the current-controlling device is configured to supply current to the series-field winding so as to ensure a field flux does not equal zero. Thus, the current-controlling device has the effect of limiting the maximum speed of the DC motor.

A semiconductor device for controlling a three-phase motor with double windings, includes a first inverter that drives a first winding of the three-phase motor, a second inverter that drives a second winding of the three-phase motor and a communication line between the first and second inverters. The first and second inverters, through the communication line, notify a respective operation state each other.

A motor controller comprises: a rotation angle estimation unit for estimating and computing a rotation angle of a motor repeatedly based on the current and voltage of the motor without using a motor rotation angle detector; a speed calculation unit for calculating the period of the signal waveform of the rotation angle that is repeatedly estimated and calculated by the rotation angle estimation unit and for calculating an actual rotational speed of the motor based on the period; a drive signal generating unit for generating a drive signal to drive and control the motor based on at least a deviation between the actual rotational speed and a target rotational speed and the rotation angle; and a switching circuit that is switched based on the drive signal to provide drive power to the motor.

A motor controller comprises: a rotation angle estimation unit for estimating and computing a rotation angle of a motor repeatedly based on the current and voltage of the motor without using a motor rotation angle detector; a speed calculation unit for calculating the period of the signal waveform of the rotation angle that is repeatedly estimated and calculated by the rotation angle estimation unit and for calculating an actual rotational speed of the motor based on the period; a drive signal generating unit for generating a drive signal to drive and control the motor based on at least a deviation between the actual rotational speed and a target rotational speed and the rotation angle; and a switching circuit that is switched based on the drive signal to provide drive power to the motor.

An interface circuit, including: a micro control unit (MCU), an isolated power supply, and a signal isolating circuit. The MCU, the isolated power supply, and the signal isolating circuit are integrated on a circuit board. The output end of the isolated power supply supplies power for circuits. The input end of the isolated power supply is connected to an external input power supply. The A/D conversion input port of the MCU is connected to the analog voltage signals. The MCU is configured to convert the analog voltage signals into pulse width modulation (PWM) signals or variable frequency signals with certain duty cycles, and output the PWM signals or the variable frequency signals to the input end of the signal isolating circuit. The signal isolating circuit is configured to output the PWM signals or the variable frequency signals with certain duty cycles.

An interface circuit, including: a micro control unit (MCU), an isolated power supply, and a signal isolating circuit. The MCU, the isolated power supply, and the signal isolating circuit are integrated on a circuit board. The output end of the isolated power supply supplies power for circuits. The input end of the isolated power supply is connected to an external input power supply. The A/D conversion input port of the MCU is connected to the analog voltage signals. The MCU is configured to convert the analog voltage signals into pulse width modulation (PWM) signals or variable frequency signals with certain duty cycles, and output the PWM signals or the variable frequency signals to the input end of the signal isolating circuit. The signal isolating circuit is configured to output the PWM signals or the variable frequency signals with certain duty cycles.

Sex toy as a vibrator for erogenous stimulation, including an electric motor drive that rotationally drives at least one eccentric inertial mass. The inertial mass eccentrically rotates in a rotational frequency range, and therefore the vibrator vibrates in this frequency range and thus in its working oscillation frequency range. The diameter of the motor drive is between 5 mm and 50 mm. The vibrator is designed in such a way that during operation it is virtually acoustically imperceptible.

A system includes a remote electronic tilt phase shifter module, a motor, a mechanical linkage that connects the motor to the remote electronic tilt phase shifter module, a current management circuit that generates a motor control signal responsive to a current control signal, and a driver circuit that is configured to selectively connect the motor to a power supply in response to the motor control signal.