Motor drive control device

摘要

A motor drive control device is provided in which if any abnormality occurs in a drive control circuit, drive command signals the drive control circuit generates are interrupted at once, so that an AC motor can be stopped in safety. A monitor control circuit and drive command signal interruption circuit are provided to the drive control circuit that takes variable-speed control of the AC motor supplied with power from a DC drive power source via a semiconductor bridge circuit. If any abnormality occurs in the drive control circuit, the drive command signals the drive control circuit generates are interrupted at once. When starting operation, the drive control circuit and monitor control circuit cooperate with each other to conduct preliminary check as to whether or not the drive command signal interruption circuit operates normally, base on a predetermined time schedule, and stop the AC motor without fail if any abnormality occurs during operation.

主权项

1. A motor drive control device, comprising:
a semiconductor bridge circuit in which positive side switching elements connected to a positive side terminal of a DC drive power source are connected in series with their respective negative side switching elements connected to a negative side terminal thereof, and series-connection points of a plurality of switching elements connected in series are connected with their respective drive terminals of an AC motor; a drive control circuit that sequentially generates positive side and negative side drive command signals to the positive side switching elements and the negative side switching elements, and takes variable-speed control of the AC motor; a monitor control circuit that transmits mutually-monitoring signals to and from the drive control circuit, monitors an operation state of the drive control circuit at all times, and if any abnormality is detected, generates a first abnormality detection signal to initialize and restart the drive control circuit; and a drive command signal interruption circuit that is placed in transmission paths for the positive side and negative side drive command signals, and interrupts at once all of the positive side and negative side drive command signals by a first inhibit command signal the drive control circuit generates or by a second inhibit command signal the monitor control circuit generates; wherein command state monitoring signals are input in at least either one of the drive control circuit and the monitor control circuit; the command state monitoring signals are either positive side and negative side command output signals the drive command signal interruption circuit generates, or switching operation monitoring signals of the switching elements, that respond to operation status of the positive side switching elements and the negative side switching elements; the drive control circuit, immediately after powered on or during an operation pause period of at least the AC motor stopping, also transmits to the monitor control circuit a check-start command signal, and following that, sequentially generates the positive side and the negative side drive command signals and the first inhibit command signal based on a predetermined time schedule; the monitor control circuit, after receiving the check-start command signal, generates the second inhibit command signal in a predetermined time slot based on the predetermined time schedule, and the drive control circuit or the monitor control circuit in which the command state monitoring signals are input determines whether or not logical change of the command state monitoring signals is taking place in the predetermined time slot based on the predetermined time schedule; if the drive control circuit determines that logical change is not properly taking place, the drive control circuit stops generation of the drive command signals, and also continues to generate the first inhibit command signal; if the monitor control circuit determines that logical change is not properly taking place, the monitor control circuit continues to generate the second inhibit command signal; and the drive control circuit and the monitor control circuit cooperate with each other to conduct operation check of the drive command signal interruption circuit, when the interruption function is normal, start rotational drive of the AC motor; meanwhile if any abnormality occurs in the drive control circuit during operation, the drive control circuit and monitor control circuit stop the rotational drive of the AC motor by the first inhibit command signal or the second inhibit command signal.