A motor drive apparatus includes: a rectifier; an inverter; a DC link voltage detection unit; an input current detection unit configured to detect input current inputted to the rectifier; a DC link voltage comparison unit configured to compare a DC link voltage with a first voltage threshold value and with a second voltage threshold value; a current comparison unit configured to compare the input current with a current threshold value; and an abnormality detection unit configured, in a case that the DC link voltage is smaller than the first voltage threshold value or that the DC link voltage is greater than the second voltage threshold value, to determine that a first abnormality has occurred when the input current is smaller than the current threshold value and to determine that a second abnormality has occurred when the input current is equal to or greater than the current threshold value.

The disclosure relates to a method for determining an incorrect operating state of an electrical machine with the aid of an electronic circuit having at least one comparator. The electrical machine is controlled with a pulse width modulation signal. The pulse width modulation signal is demodulated. A first signal, which represents the demodulated pulse width modulation signal, is compared with a second signal. The second signal represents a rotational speed or a rotational angle of the electrical machine and/or a current intensity of the electrical machine. This comparison is carried out with the aid of the at least one comparator. An error signal is generated based on the comparison in order to determine the incorrect operating state of the electrical machine.

A heat pump device is equipped with a compressor for compressing a refrigerant; a converter for converting a voltage of an alternating current power supply into a boosted direct current; an inverter for converting the direct current output of the converter into an alternating current, supplying the alternating current to the compressor; a voltage detector for detecting an input voltage to the converter; a stop controller for stopping operation of the converter and the inverter when resonance occurs in the voltage detected by the voltage detector; a limit controller for sending an instruction to limit an input current to the converter so as to avoid the resonance; and a manually operable input interface for sending an instruction to cause the limit control unit to operate.

A secure roller controller of a roller conveyor system for logistics services includes a monitoring circuit, a controller module and a driving circuit and is electrically connected to a motor. The monitoring circuit is electrically connected to the controller module and the driving circuit to receive a power signal from the driving circuit. The controller module is electrically connected to the driving circuit to receive the power signal and instruct the driving circuit to drive the motor for speed adjustment according to the power signal. When instantly detecting that the power signal is irregular, the monitoring circuit transmits an irregularity signal to the controller module for the controller module to instantly decelerate a rotation speed of the motor to a safe rotation speed through the driving circuit. Accordingly, burn-down of the motor and the secure roller controller can be avoided to enhance operational stability and safety.

A circuit for detecting a status of a ground connection in an electric motor includes a rectifier, a converter, a voltage conditioning circuit, a leakage circuit, and a comparator. The rectifier couples to an AC line within the motor and generates a first DC voltage. The converter steps-down the first DC voltage to a second DC voltage. The voltage conditioning circuit couples to the converter, leakage circuit, and comparator, and generates a reference DC voltage signal and a leakage voltage from the second DC voltage. The leakage circuit includes an impedance coupled to ground, and applies the leakage voltage to the impedance and generates a measurement signal representing a leakage current through the impedance to ground. The comparator couples to the leakage circuit and generates a logic signal, indicating a status of the ground connection, based on a voltage difference between the reference DC voltage signal and the measurement signal.

An induction machine with localized voltage unbalance compensation is disclosed. The use of an induction machine with a voltage unbalance correction compensator (VUC) may be used to maintain proper working conditions of the machine during intervals of voltage unbalance.

A motor drive device includes an inverter circuit, a switching circuit that switches between conduction and interruption between a power supply and the inverter circuit, and a switching driver that outputs, to the switching circuit, a command voltage which commands a switching operation. The switching circuit includes a first field-effect transistor (FET) and a second FET connected in series with sources of each other in order from a side of the power supply, and the switching driver includes an output circuit that outputs an interruption command voltage in a case in which a potential difference between drains of the FETs exceeds a threshold value, and a delay circuit that causes a timing at which the command voltage is input to a gate of the first FET to be later than a timing at which the command voltage is input to a gate of the second FET.

A circuit for detecting a status of a ground connection in an electric motor includes a rectifier, a converter, a voltage conditioning circuit, a leakage circuit, and a comparator. The rectifier couples to an AC line within the motor and generates a first DC voltage. The converter steps-down the first DC voltage to a second DC voltage. The voltage conditioning circuit couples to the converter, leakage circuit, and comparator, and generates a reference DC voltage signal and a leakage voltage from the second DC voltage. The leakage circuit includes an impedance coupled to ground, and applies the leakage voltage to the impedance and generates a measurement signal representing a leakage current through the impedance to ground. The comparator couples to the leakage circuit and generates a logic signal, indicating a status of the ground connection, based on a voltage difference between the reference DC voltage signal and the measurement signal.

The present disclosure discloses an IGBT driving circuit for an electric-motor controller and an electric-motor controller. The IGBT driving circuit includes: a function safety circuit provided on a driver board of the electric-motor controller, and a detection feedback circuit and a pulse-width-modulation (PWM) buffer circuit that are connected to the function safety circuit. The detection feedback circuit is configured to detect an IGBT module of the electric-motor controller, and when a specified malfunction of the IGBT module is detected, send a specified-malfunction signal to the function safety circuit. The function safety circuit is configured to judge according to a preset malfunction treating rule and the received specified-malfunction signal, and then output a corresponding controlling signal to the PWM buffer circuit. The PWM buffer circuit is configured to generate according to the corresponding controlling signal a PWM signal that drives the IGBT module, to control ON/OFF of the IGBT module to protect the IGBT module. The technical solutions of the present application have multiple functions of protection, which improves the stability and the safety of the IGBT, and has quick action and timely protection.

A method and a device for bringing a textile machine to a controlled standstill in the event of a failure of the power supply, and a correspondingly equipped textile machine, the textile machine having at least two axes that are driven in synchronization by respective electric motors (M.sub.1-M.sub.5) connected to a common intermediate voltage circuit (1), and in which at least one electric motor acting as power generator can supply electric power to at least one other electric motor via the common DC bus (1), and in which the voltage (V) on the common DC bus is controlled by varying at least two variables in such a way that the voltage follows a previously defined curve while the textile machine is being brought to a standstill.