Inverter Controller Slip Frequency Adjustment for Beat Suppression
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Solution Overview
Problem
Existing power conversion devices fail to promptly correct pulses caused by load fluctuations and power supply variations in induction motors, leading to beat phenomena and potential overcurrent issues.
Innovation Solution
A power conversion device with a converter and inverter system that includes a current detector to adjust the slip frequency in response to AC current fluctuations, enabling prompt pulse correction and suppressing beat components by controlling the inverter output frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inverter controller detects pulse on the DC side of the inverter to control output frequency, then the pulse correction operation can be performed, but the response is delayed because the output voltage of the converter hardly changes in response to load fluctuation
Solution Approach 1:
The patent introduces an AC current detector on the input side of the converter as an intermediary measurement point. This detector directly captures load fluctuations and power supply variations before they pass through the converter, providing immediate feedback to the inverter controller for prompt pulse correction without waiting for DC voltage changes.
Solution Approach 2:
The patent implements a feedback mechanism where the inverter controller continuously monitors AC current on the input side of the converter and adjusts the inverter output frequency based on detected fluctuations. This closed-loop feedback enables real-time pulse correction by comparing actual current with expected current and compensating for deviations.
2Reliability
If the inverter controller uses frequency control means to suppress beat phenomenon, then the beat phenomenon can be corrected, but the device fails to respond promptly to load fluctuation and power supply variation
Solution Approach 1:
The patent makes the frequency control means universal by enabling it to handle multiple types of fluctuations simultaneously. The AC current detector on the input side captures both load fluctuations (from motor speed changes) and power supply fluctuations (from other vehicles on the same wiring), allowing the inverter controller to suppress beat phenomena from either source using the same control mechanism.
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
The solution effectively suppresses beat components and prevents overcurrent in induction motor currents, ensuring stable operation by promptly addressing load and power supply fluctuations.
Implementation Method 1
a converter that converts AC power from an AC power supply to DC power
Implementation Method 2
an inverter that converts the DC power to AC power at a variable frequency
Implementation Method 3
a current detector that detects an AC current on an input side of the converter
Data Source
AI summary
A power conversion device includes a converter that converts AC power to DC power, a converter controller that controls an output voltage of the converter, an inverter that converts the DC power to AC power at a variable frequency, an inverter controller that controls an output frequency of the inverter, and a current detector that detects an AC current on an input side of the converter. It is configured in such a manner that the inverter controller adjusts a slip frequency of the induction motor in response to a fluctuation of the AC current on the input side of the converter detected by the current detector. It thus becomes possible to suppress a beat current in an output current of the inverter at the occurrence of a load fluctuation as well as a power supply voltage fluctuation.