Motor Drive Discharge via Charging Resistor

Solution Overview

Problem

Existing motor driving apparatuses face challenges in efficiently discharging stored charge from power storage units, leading to increased costs and complexity due to methods that either rely on self-discharge, separate discharging units, or require enhanced cooling capacities.

Innovation Solution

A motor driving apparatus that incorporates an initial charging unit with a switch and charging resistor to initially charge and subsequently discharge the power storage unit using the charging resistor, allowing for rapid discharge without the need for additional components or increased cooling, and includes a control unit to manage the discharging process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate discharging unit with switch and discharging resistor is provided, then the charge can be discharged rapidly, but the device complexity and cost increase

Engineering Contradiction:

Improvedischarge speedVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The charging resistor is designed to serve dual purposes: charging the power storage unit during initial operation and discharging it after motor completion. This multi-functionality eliminates the need for a separate discharging unit, reducing device complexity while maintaining rapid discharge capability through controlled switching of the resistor's function

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the charging and discharging functions into a single resistor component. By combining these two previously separate functions into one component, the overall device complexity is reduced while still achieving the goal of rapid charge discharge for safety

Inventive Principle:

Principle #5Merging (Combining)

2Device complexity

If self-discharge method is used, then the device complexity is reduced, but the discharge time is excessively long

Engineering Contradiction:

Improvedevice complexityVSAvoiddischarge time

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The system dynamically switches the charging resistor's function from charging to discharging mode after motor completion. This dynamic reconfiguration allows the same component to provide rapid discharge when needed, reducing discharge time from hours (self-discharge) to seconds while maintaining simple device architecture

Inventive Principle:

Principle #15Dynamics

3Reliability

If a separate discharging unit is provided, then rapid discharge is achieved, but the mounting area and cost increase

Engineering Contradiction:

Improvedischarge speedVSAvoidmounting area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The charging resistor is designed to serve dual purposes: charging the power storage unit during initial operation and discharging it after motor completion. This multi-functionality eliminates the need for a separate discharging unit, reducing device complexity while maintaining rapid discharge capability through controlled switching of the resistor's function

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the charging and discharging functions into a single resistor component. By combining these two previously separate functions into one component, the overall device complexity is reduced while still achieving the goal of rapid charge discharge for safety

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If enhanced cooling capacity is provided, then the discharge process can be managed, but the device complexity and cost increase

Engineering Contradiction:

Improvedischarge controlVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system uses periodic switching of the charging resistor's function - first for charging during initial operation, then for discharging after motor completion. This time-based functional switching manages the discharge process effectively without requiring enhanced cooling capacity or increased device complexity

Inventive Principle:

Principle #19Periodic action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables rapid discharge of stored charge, reducing the risk of electric shock and preventing overheating, while maintaining a compact and cost-effective design by utilizing the charging resistor for both charging and discharging, thus avoiding the need for additional mounting area and cooling enhancements.

Implementation Method 1

discharge the charge stored in the power storage unit by a current flowing through the charging resistor

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS10224862B2Motor driving apparatus having discharging function

Publication Date: 2019.03.05 FANUC LTD

AI summary

A motor driving apparatus includes an AC-DC conversion unit that converts AC power into DC power, a power storage unit provided in a DC link between the AC-DC conversion unit and a DC-AC conversion unit, an initial charging unit that is provided in the DC link, includes a switch unit and a charging resistor connected to the switch unit in parallel, and initially charges the power storage unit, an electromagnetic contactor that opens and closes an electrical path between the AC power source and the AC-DC conversion unit, and a control unit, and after completion of driving of a motor, the control unit performs an opening operation on the electromagnetic contactor and the switch unit and performs a turn-on operation on each of the switching devices provided on the upper and lower arms in the same phase to discharge charge stored in the power storage unit by the charging resistor.