An MMC-type power conversion device includes a failure detection unit that detects presence or absence of failure of each of n upper arm current detectors and n lower arm current detectors. The failure detection unit makes a first determination based on comparison between a sum of detection values of n upper arm current detectors and the sum of detection values of n lower arm current detectors, a second determination based on comparison between a current command value and the sum of detection values of n upper arm current detectors, a third determination based on comparison between a current command value and the sum of detection values of n lower arm current detectors, and a fourth determination of comparing, for each phase, the sum of detection values of the current detectors of an upper arm and a lower arm of the same phase.

A frequency converter, includes: a DC link, wherein the DC link has a first connection pole at which a positive link potential is present during operation of the frequency converter, and a second connection pole at which a negative link potential is present during operation of the frequency converter; an inverter, wherein the inverter has a first connection pole at which a positive inverter potential is present during operation of the frequency converter, and a second connection pole at which a negative inverter potential is present during operation of the frequency converter; a resistive shunt which is looped in between the first connection pole of the DC link and the first connection pole of the inverter; a differential amplifier which is designed to generate a test voltage from a potential difference across the resistive shunt; and an evaluation unit which is designed to detect a ground fault based on the test voltage.

A motor drive control device capable of reliably acquiring currents of coils of two phases by a one-shunt current detection system is provided. The motor drive control device includes: a motor drive unit including an inverter circuit; a single current detection circuit connected to a direct current line of the inverter circuit, and detecting a current flowing through the direct current line; and a control circuit unit performing analog-to-digital conversion processing of the current to take in the current, and performing PWM control on the motor drive unit. The control circuit unit acquires, from the current detection circuit, a detection result of a first current and a second current being currents of coils of two phases among coils of three phases in a half cycle of one PWM cycle, and, when the A/D conversion processing of at least one of the first current and the second current is unsuccessful, reacquires, in the same PWM cycle or a next or subsequent PWM cycle, a detection result of only the current unsuccessful in the A/D conversion processing, and performs the A/D conversion processing of the reacquired detection current.

The present invention relates to a system and method for the monitoring and detection of insulation degradation in electric systems. The system comprises a controller for an electric motor (3), including input circuitry (2a) for connecting the controller to a power supply (1), power conversion circuitry (2b) for providing a power output for the electric motor (3), and sensing circuitry (2c) for monitoring a current inside the controller that is representative of a return leakage current from the electric motor to the motor controller. A condition of the insulation may be determined based on the monitored current.

A control circuit for a resonant converter, can include: a feedforward circuit configured to generate a feedforward current; a charge feedback circuit configured to receive a resonant current sampling signal representing a resonant current of the resonant converter in a first mode to generate a charge feedback signal, and to receive the resonant current sampling signal and the feedforward current together to generate the charge feedback signal in a second mode; and a driving control circuit configured to generate driving signals according to the charge feedback signal and a first threshold signal, in order to control switching states of power transistors of the resonant converter, where the first threshold signal is generated according to an error compensation signal representing an error information between a feedback signal of an output signal of the resonant converter and a reference signal.

The application provides a current detecting circuit, including a current transformer having a primary winding for receiving a current to be detected and a secondary winding for generating a sampling current; a demagnetizing circuit for demagnetizing the current transformer; a chip selection circuit electrically connected to the demagnetizing circuit, and operably switched between a first mode and a second mode; a sampling circuit electrically connected to the chip selection circuit to sample the sampling current, and outputting a sampling signal to a controller; and a clamping circuit electrically connected between the sampling circuit and the controller, and configured for providing a reference potential. The application further provides a converter including the current detecting circuit.

A drive controller is used in a control system of a power factor correction (PFC) circuit. The control system further includes the PFC circuit. The PFC circuit includes a first bridge arm, a second bridge arm, a first switching transistor, and a second switching transistor. The driving controller includes a sampling circuit and a driving circuit. The sampling circuit is configured to obtain a target current value between the first switching transistor and the second switching transistor. The drive circuit is configured to turn off gate inputs of the first switching transistor and the second switching transistor when the target current value is greater than a current threshold, to turn off the first switching transistor and the second switching transistor and protect the control system.

A controller of a switching converter includes an error amplifying circuit, a first comparison circuit, a valley detection circuit, a valley selection circuit and a frequency control circuit. The error amplifying circuit generates a compensation signal based on the difference between a reference signal and a feedback signal. The first comparison circuit compares the compensation signal with a modulation signal and generates a pulse frequency modulation signal. The valley detection circuit detects valleys of a resonant voltage of the switching converter and generates a valley pulse signal. The valley selection circuit generates a valley enable signal corresponding to a target valley number based on the pulse frequency modulation signal and the valley pulse signal. The frequency control circuit generates a frequency control signal to control the switching frequency of the first switch based on the valley enable signal and the valley pulse signal.

A converter to convert an input voltage into a regulated output current for supplying a load includes a reverse current protection diode having an anode coupled to the input voltage and a cathode, an energy storage element coupled to the cathode of the reverse current protection diode, a high side transistor coupled to the energy storage element and responsive to a high side control signal, and a low side transistor coupled to the energy storage element and responsive to a low side control signal. A controller is configured to generate the high side control signal and the low side control signal such that the low side transistor is enabled and the high side transistor is disabled during a pre-regulation interval.

A Buck constant voltage driver and an application circuit thereof, are disclosed. In the Buck constant voltage driver, the peripheral structure is remained unchanged for possessing the advantages of low cost and simplicity of the prior art. Meanwhile, in order to compensate the difference of output voltage caused by the change of the forward voltage drop under different output currents, an output voltage compensation module is added to the Buck constant voltage driver. The output voltage compensation module is operable to acquire an output current information based on the sampling voltage on the sampling resistor, and to compensate the preset first reference voltage according to the output current information, thus maintaining the output voltage of the Buck constant voltage driver constant, under different output current conditions.