Motor Inverter Phase Compensation for Input Harmonic Reduction
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Solution Overview
Problem
Harmonic components in the induced voltage of a motor generate corresponding harmonics in the input power, leading to increased harmonics at the input side of the inverter circuit, which can exceed power supply harmonic restriction values, particularly at higher motor speeds, thereby reducing the operating range of the motor.
Innovation Solution
A power conversion apparatus with a compensation unit that detects harmonic components synchronised with motor speed and adjusts the phase of the alternating current voltage output from the inverter circuit at the same frequency as the harmonic, reducing harmonic generation without altering the voltage control factor, thus maintaining the motor's operating range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor operates at higher speeds, then the productivity increases, but the harmonic components in the input power increase, causing the harmonics at the input side of the inverter circuit to exceed power supply harmonic restriction values
Solution Approach 1:
The patent detects harmonic components in the input power and generates a compensation voltage with the same frequency as the detected harmonic. By adding this compensation voltage to the fundamental wave voltage, the patent converts the harmful harmonic effect into a beneficial cancellation mechanism, where the compensation voltage counteracts the harmonic distortion in the input power, allowing the motor to operate at higher speeds without exceeding harmonic restriction values.
Solution Approach 2:
The patent dynamically adjusts the amplitude and phase of the compensation voltage based on the detected harmonic components. By changing these parameters according to the motor speed and load conditions, the system maintains effective harmonic cancellation across different operating points, enabling high-speed operation while complying with harmonic restrictions.
2Object-affected harmful factors
If compensation methods are applied to reduce harmonics, then the power supply harmonic restrictions are met, but the motor operating range may be reduced
Solution Approach 1:
The patent employs a feedback mechanism where the harmonic components in the input power are continuously detected, and the compensation voltage is adjusted accordingly. This closed-loop control ensures that the compensation is precisely tailored to the actual harmonic conditions, maintaining motor performance across the full operating range while meeting harmonic restrictions.
Solution Approach 2:
The compensation voltage is dynamically adjusted based on real-time detection of harmonic components and motor operating conditions. The amplitude and phase of the compensation voltage change adaptively with motor speed and load, preserving the motor's full operating range while effectively reducing harmonics at different operating points.
Data Source
AI summary
A power conversion apparatus that converts an input alternating current power supplied from an alternating current power supply into an output alternating current power having a predetermined voltage and frequency, includes an inverter circuit configured to supply the output alternating current power to a motor, and a compensation unit configured to compensate for a harmonic of an input power of the motor, and the compensation unit detects a harmonic component generated in synchronism with a speed of the motor in the input power, and varies a phase of an alternating current voltage output from the inverter circuit at the same frequency as the harmonic component, so as to reduce the harmonic component.