Motor Drive DC Link Abnormality Detection Without Main Power

Solution Overview

Problem

Conventional motor drive devices require expensive and large resistors to detect abnormalities in the DC link unit, posing a risk of damage when AC power is applied, as they rely on main power supply voltage to assess the DC link unit's condition.

Innovation Solution

A motor drive device with a voltage application unit independent of the main power supply applies voltage to the DC link unit, using a voltage detector and abnormality determination unit to assess the DC link unit's condition without main power supply activation, allowing safe power application and preventing device breakdown.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If main power supply voltage is applied to detect DC link unit abnormality, then abnormality detection is enabled, but expensive and large resistors are required

Engineering Contradiction:

Improveabnormality detection capabilityVSAvoidresistor size

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The system performs preliminary abnormality detection by applying voltage from the converter before main power supply activation. The converter charges the DC link capacitor to a predetermined voltage level, enabling abnormality detection without requiring large resistors that would be needed for direct main power supply connection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The converter acts as an intermediary device between the main power supply and the DC link unit for detection purposes. Instead of directly applying main power supply voltage through large resistors, the converter indirectly applies voltage to detect abnormalities, using its output to charge the DC link capacitor to a safe detection level.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If main power supply voltage is applied to detect DC link unit abnormality, then abnormality detection is enabled, but device cost increases

Engineering Contradiction:

Improveabnormality detection capabilityVSAvoiddevice cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The system performs preliminary abnormality detection by applying voltage from the converter before main power supply activation. The converter charges the DC link capacitor to a predetermined voltage level, enabling abnormality detection without requiring large resistors that would be needed for direct main power supply connection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The converter acts as an intermediary device between the main power supply and the DC link unit for detection purposes. Instead of directly applying main power supply voltage through large resistors, the converter indirectly applies voltage to detect abnormalities, using its output to charge the DC link capacitor to a safe detection level.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If main power supply is activated without prior abnormality check, then device can operate immediately, but risk of damage increases

Engineering Contradiction:

Improvedevice startup speedVSAvoiddevice safety

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system performs preliminary abnormality detection by applying voltage from the converter before main power supply activation. The converter charges the DC link capacitor to a predetermined voltage level, enabling abnormality detection without requiring large resistors that would be needed for direct main power supply connection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system takes preliminary protective action by detecting DC link unit abnormalities before main power supply activation. If an abnormality is detected, the main power supply activation is prevented, avoiding potential damage to the inverter and other components.

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS9294024B2Motor drive device having function of detecting abnormality of DC link unit

Publication Date: 2016.03.22 FANUC LTD

AI summary

A motor drive device according to one embodiment of the present invention includes a converter (2) for converting an AC voltage input from a main power supply into a DC voltage, a DC link unit (4) for rectifying the DC voltage output from the converter, an inverter (10) for converting the DC voltage rectified by the DC link unit into an AC voltage for driving a motor using a semiconductor switching element, a voltage application unit (6) that is provided independently of the main power supply to apply a voltage to the DC link unit, a voltage detector (7) for detecting a voltage of the DC link unit after application of the voltage by the voltage application unit, and an abnormality determination unit (8) for determining the presence or absence of an abnormality of the DC link unit based on the voltage detected by the voltage detector.