A motor drive device includes a plurality of control systems that individually supply drive currents to a plurality of coil groups included in a motor. The motor drive device independently sets the current command values for the respective control systems. Based on the set current command values, drive instructions are supplied to drive circuits of inverters with respect to the respective control systems, thereby supplying drive currents from the inverters to the coil groups. The motor drive device detects a failure in any of the inverters and the coil groups with respect to each control system, and stops only the failed control system or causes only the failed control system to fall back. The motor drive device further includes a main computing device, and an auxiliary computing device. Consequently, if the auxiliary computing device is normal even in case the main computing device fails, driving of the motor can be continued using one or some of the control systems.

A chiller system (200) includes a motor (212), a motor controller (214) connected to the motor (212), the motor controller (214) operative to send a control signal to the motor (212), a rectifier (206) connected to an alternating current (AC) power source (204), the rectifier (206) operative to receive AC power and output direct current (DC) power, a DC bus (208) connected to the rectifier (206), a first inverter (210) connected to the DC bus (208) and the motor (212), the first inverter (210) operative to receive DC power from the DC bus (208) and output AC power to the motor (212), and a second inverter (213) connected to the DC bus (208) operative to receive DC power and output AC power to the motor controller (214).

Power conversion systems and methods are provided for ride through of abnormal grid conditions or disturbances, in which a system rectifier is operated in a first mode to regulate a DC voltage of an intermediate DC circuit, an inverter is operated in the first mode to convert DC power from the intermediate DC circuit to provide AC output power to drive a load. In response to detecting an abnormal grid condition, the system changes to a second mode in which the rectifier is turned off and the inverter regulates the DC voltage of the intermediate DC circuit using power from the load.

The present invention relates to an apparatus for controlling the operation of a power conversion device including a rectifier part, an initial charging part, a DC-link part and an inverter part. The apparatus includes: a control part configured to drive a relay connected in parallel to an initial charging resistor of the initial charging part if a DC-link voltage of the DC-link part exceeds a first reference voltage during initial charging for the DC-link part; a relay monitoring part configured to monitor whether or not the relay is normally being operated when the relay is driven; and an inverter driving part configured to stop of the driving of the inverter part if it is determined that the relay is not normally being operated by referring to a result of the monitoring of the relay monitoring part.

A motor control device includes: a rectifier that converts AC power supplied from an AC power supply side into DC power and outputs the DC power; an inverter that converts the DC power output from the rectifier into AC power for motor driving and outputs the AC power; an AC voltage detection unit that detects an AC voltage value of an AC power supply side of the rectifier; and a power failure detection unit that outputs, based on the AC voltage value detected by the AC voltage detection unit, several power failure detection signals in accordance with a predetermined power failure detection condition at a power failure on the AC power supply side of the rectifier.

The present disclosure relates to an inverter, and more specifically to an inverter that can be restarted stably by determining whether to restart it when power is supplied after a failure has occurred in the inverter due to a fault in the main supply.

A motor controller includes a rectifier for converting AC power supplied from an AC power supply into DC power and outputting the DC power; an AC voltage detector for detecting an AC voltage value of the AC power supply and outputting the AC voltage value as a detection value; a power failure detector for determining that a power failure is occurring, when a state in which the outputted detection value is equal to or lower than a regulation voltage has continued for a regulation time or more; and a power failure detection condition determiner for determining or modifying the regulation time.

A motor control device which controls a motor in a machine tool or an industrial machine includes: a power outage detection unit that detects a power outage of a power source which supplies electric power for driving the motor; a DC link voltage detection unit that detects a value of a DC link voltage applied to an amplifier which drives the motor; a comparison unit which compares the value of the DC link voltage with a predetermined threshold value; a torque command generation unit which generates a torque command for driving the motor; a torque limit value setting unit which sets a torque limit value in accordance with a result of a comparison by the comparison unit; and a torque command limit unit which limits the torque command to the torque limit value when a power outage is detected by the power outage detection unit.

A motor control device includes: a power failure detection unit that detects a power failure; a voltage detection unit that detects a DC link voltage; a switch unit which connects a motor to an amplifier or a resistance; a voltage comparison unit which compares a DC link voltage with a threshold value; a limit value setting unit which sets a torque limit value in accordance with a result of comparison; a torque command limit unit which limits a torque command when a power failure is detected; a prediction value calculation unit which calculates, using an angular velocity, a torque prediction value of the motor when the motor is connected to the resistance; and a torque comparison unit which compares the torque limit value with the torque prediction value, in which in accordance with a result of comparison, the switch unit connects the motor to the amplifier or the resistance.

A functional safety system with high reliability is provided. The functional safety system includes power source apparatuses VS1 and VS2, voltage monitoring apparatuses VM1 and VM2, semiconductor devices SC1 and SC2, interruption circuits IN1 and IN2, and a motor MT. A the voltage converting circuit DA1 of the voltage monitoring apparatus VM1 generates a detected voltage VA1 from a power source voltage VDD1 on the basis of a switching signal VC1, and a voltage converting circuit DA2 of the voltage monitoring apparatus VM1 generates a detected voltage VA2 from the power source voltage VDD1 on the basis of a switching signal VC1.