A chopper device includes: a series circuit connecting at one end to a positive pole of a DC power source and having a breaker and a reactor; a series circuit connected between another end of the stated series circuit and a negative pole of the DC power source and having switches; a series circuit connected in parallel to the switch and having a diode and a capacitor; and a series circuit connected in parallel to the switch and having a diode and a capacitor. The chopper device outputs a DC voltage at three potentials from both ends and a midpoint of a series circuit having the capacitors by turning the switches ON/OFF. The chopper device further includes other switches connected in parallel to the switches. When a short-circuit fault is presumed to have occurred in the switch, the other switch is turned ON before interruption is performed by the breaker.

An exemplary motor driving system includes a power source, a driving circuit, a controller, a motor, and a protection circuit. The driving circuit including at least one switching device coupled with the power source. The motor includes a plurality of windings. The motor is coupled with the driving circuit and driven by the driving circuit. The controller is configured to provide first switch signals to the at least one switching device of the driving circuit in a normal mode. The protection circuit is coupled with the controller, and configured to generate second switch signals based at least in part on a fault signal in a fault mode and provide the second switch signals to the at least one switching device of the driving circuit so as to reconstruct circuit loops between the driving circuit and the plurality of windings. A method for operating the motor driving system is also described.

A power conversion device may include a first inverter to which one end of each phase winding of a motor is coupled, a second inverter to which the other end of each phase winding is coupled, and a switch circuit having at least one of a first switch element that switches between connection and disconnection of the first inverter to and from a ground, a first protection circuit being coupled in parallel to the first switch element, and a second switch element that switches between connection and disconnection of the second inverter to and from the ground, a second protection circuit being coupled in parallel to the second switch element.

A power tool is provided including a housing, a brushless direct-current (BLDC) electric motor disposed inside the housing, power switches disposed between a power supply and the electric motor and including high-side switches and low-side switches, and a control unit configured to control a switching operation of the power switches to operate the electric motor and electronically brake the motor by simultaneously activating the high-side switches or the low-side switches to stop the rotation of the motor upon detection of a condition prompting the braking of the motor. The control unit is configured to detect the condition that prompts the braking of the electric motor, set a braking profile for braking the electric motor based on the detected condition, and execute braking of the electric motor using the braking profile.

A switching control unit that ON/OFF-controls switching elements of a power conversion circuit includes a power supply side abnormality determination unit, and a regeneration abnormality response processing selection unit that selects either three-phase short circuit processing, in which all upper stage side switching elements or all lower stage side switching elements are switched ON, or six-switch opening processing, in which all of the switching elements of the power conversion circuit are switched OFF, as processing to be executed when the power supply side abnormality determination unit determines that a power supply side abnormality has occurred, the three-phase short circuit processing and the six-switch opening processing being selected in accordance with a motor operating condition of the AC motor at the time of the determination.

A motor braking unit for a washing machine that offers high braking efficiency while preventing overcharging a capacitor in a DC link. The motor braking unit determines a current to be supplied to the motor based on a detected speed of the motor. The motor braking unit dynamically monitors the voltage on the capacitor against a reference voltage. If the capacitor voltage is lower than the reference voltage, the current component Iq is increased to increase the braking torque; and if the capacitor voltage is greater than the reference voltage, the current Iq component is decreased to prevent overcharging on the capacitor by the motor.

Systems, methods, and computer-readable storage media for monitoring electrical patterns of a motor-driven system. The system first obtains respective measurements of relevant electrical parameters of a motor during operational stages including a start-up stage, a transition stage, a steady-state stage, idle stage, or a shutdown stage of the motor driven system driven by the motor. Based on the respective measurements, the monitoring system then determines respective electrical patterns corresponding to the operational stages. Next, the monitoring system compares the respective electrical patterns corresponding to the operational stages with respective baseline electrical patterns modeled for the operational stages to yield a comparison. Then, the monitoring system determines a status of the motor driven system based on a comparison between baseline and observed operating parameters.

The structure for detecting tooth-skipping of the speed reducer of the rotary driver is reduced in weight and size. In the rotary driver the occurrence of tooth-skipping is detected based on the difference in outputs from the encoders located at the input side (the side of the motor) and at the output side (the side of the load), which is opposite the input side in relation to the speed reducer. The rotary driver comprises a motor, a speed reducer located between the motor and a load to reduce the rotary speed of a rotary shaft at the side of the motor, to thereby transmit the reduced rotary speed to a rotary shaft at the side of the load, a first encoder for detecting a rotation of the rotary shaft at the side of the motor, a second encoder for detecting a rotation of the rotary shaft at the side of the load, a section for detecting any difference between a first detected value that is obtained by dividing an output of the first encoder by a rate for reducing the speed by the speed reducer and a second detected value that is obtained from an output of the second encoder, and a section for detecting tooth-skipping that detects tooth-skipping of the speed reducer based on the difference.

Protection of an electric motor drive controller from a transient voltage is described herein. The transient voltage is provided by an alternating current (AC) power line that includes a line conductor, a neutral conductor, and a ground conductor. The transient voltage protection system includes a first stage protection device coupled to an input of a rectifier of the motor drive controller. The first stage protection device is configured to suppress the transient voltage to prevent damage to the motor drive controller. The transient voltage protection system also includes a second stage protection device coupled between the rectifier and an inverter of the motor drive controller. The second stage protection device is configured to further suppress the transient voltage to prevent damage to the inverter.

An electric motor system having substantially independent hardware-based and software-based pathways for detecting and initiating responses to fault conditions, such as over-current conditions, in an electric motor which is powered by a power inverter which is controlled by a power module and a microprocessor. Each pathway involves comparing a voltage, which is representative of an electric current flowing to the motor, to a predetermined maximum voltage, and if the former exceeds the latter using hardware or software to initiate shutting off the motor, such as by shutting off the power inverter. When one pathway detects a fault condition it may notify the other pathway, and the notified pathway may also initiate shutting off the motor.