Motor Driving Apparatus DC Link Voltage Detection
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Solution Overview
Problem
Conventional motor driving apparatuses fail to detect abnormalities caused by disconnection of short bars, which can lead to dangerous situations in applications like robots or machine tools, as the DC link voltage detection unit is directly connected to the smoothing capacitor and cannot detect issues with the short bars connecting the DC link unit to the inverter unit.
Innovation Solution
The motor driving apparatus includes a DC link voltage detection unit connected to at least parts of the short bars between the terminals of the DC link unit and the inverter unit, allowing for detection of disconnections by measuring the DC link voltage through these short bars, with additional inverter units connected via other short bars, and utilizing units like voltage-dividing resistors and insulation amplifiers or photocouplers for precise detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DC link voltage detection unit is directly connected to the smoothing capacitor, then the DC link voltage can be detected reliably, but abnormalities caused by disconnection of short bars cannot be detected
Solution Approach 1:
The patent divides the voltage detection function into two separate detection units: one directly connected to the smoothing capacitor for reliable DC link voltage detection, and another connected via short bars for detecting disconnection abnormalities. This segmentation allows each detection unit to specialize in detecting specific types of abnormalities without interfering with the other's function.
Solution Approach 2:
The patent introduces an intermediary detection unit connected through the short bars that acts as a mediator to detect disconnection abnormalities. This intermediary detection unit does not replace the direct detection unit but complements it by monitoring the integrity of the short bar connections, thereby losing no information about connection status.
2Loss of information
If the DC link voltage detection unit is connected through short bars, then short bar disconnections can be detected, but the detection precision of DC link voltage decreases
Solution Approach 1:
The patent segments the detection system into two independent channels: a direct detection channel for high-precision DC link voltage measurement, and an indirect detection channel through short bars for connection status monitoring. This segmentation ensures that the measurement precision requirement is met by the direct channel while the indirect channel provides connection integrity information.
Solution Approach 2:
The patent applies partial action by using only the necessary portion of the voltage detection function for each purpose: the direct detection unit handles the precision voltage measurement requirement, while the indirect detection unit handles the connection status monitoring requirement, avoiding the need for a single unit to do both imperfectly.
3Loss of information
If multiple detection units are used to detect both DC link voltage and short bar disconnections, then detection completeness is improved, but device complexity increases
Solution Approach 1:
The patent makes the detection system universal by designing detection units that can serve multiple purposes: the direct detection unit primarily detects DC link voltage but can also detect capacitor abnormalities, while the indirect detection unit primarily detects short bar disconnections but can also detect inverter unit abnormalities. This multi-functionality reduces the need for additional specialized sensors.
Solution Approach 2:
The patent applies self-service by using the existing short bar connection structure as part of the detection pathway. The short bars, which are already present for electrical connection, also serve as the detection pathway for the indirect detection unit, eliminating the need for separate dedicated detection wiring and reducing overall system complexity.
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 configuration enables the detection of short bar disconnections, preventing dangerous situations by accurately measuring the DC link voltage and determining the occurrence of abnormalities, ensuring the reliability of motor driving systems.
Implementation Method 1
a DC link voltage detection unit configured to detect the DC link voltage, wherein at least parts of the short bars are located between terminals of the DC link unit and terminals of the DC link voltage detection unit
Implementation Method 2
a converter unit configured to convert an AC voltage into a DC voltage
Implementation Method 3
a DC link unit configured to smooth the DC voltage by a capacitor to generate a DC link voltage
Data Source
AI summary
A motor driving apparatus of the present invention includes a converter unit configured to convert an AC voltage into a DC voltage, a DC link unit configured to smooth the DC voltage by a capacitor to generate a DC link voltage, an inverter unit configured to convert the DC link voltage into a multiphase AC voltage for motor driving, short bars configured to electrically interconnect terminals of the DC link unit and terminals of the inverter unit, and a DC link voltage detection unit configured to detect the DC link voltage. At least parts of the short bars are located between the terminals of the DC link unit and terminals of the DC link voltage detection unit.