Power Converter Vector Control for Voltage Pulsation
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Solution Overview
Problem
Conventional power converters with electrolytic capacitor-less inverter circuits experience vibration, noise, and increased device loss due to pulsating direct current link voltage in over-modulation states, leading to decreased voltage utilization rates.
Innovation Solution
A power converter with an inverter circuit and controller that performs vector control to adjust the phase of the resultant voltage vector based on the pulsating component, allowing for over-modulation control and reducing the influence of direct current link voltage pulsation, thereby minimizing device loss and improving voltage utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If over-modulation control is performed in a three-phase electrolytic capacitor-less inverter, then voltage utilization rate improves, but motor vibration and noise occur due to direct current link voltage pulsation
Solution Approach 1:
The patent changes the control parameters by dynamically adjusting the phase of the resultant voltage vector based on the pulsating component of the direct current link voltage. This parameter change allows the system to operate in over-modulation state while compensating for voltage pulsation effects, thereby improving voltage utilization without causing motor vibration and noise
Solution Approach 2:
The controller detects the pulsating component of the direct current link voltage and uses this feedback information to adjust the phase of the resultant voltage vector. This feedback mechanism enables real-time compensation for voltage pulsation, allowing over-modulation control to be performed without generating harmful motor vibrations and noise
2Productivity
If over-modulation control is performed in a three-phase electrolytic capacitor-less inverter, then voltage utilization rate improves, but device loss increases
Solution Approach 1:
By dynamically changing the phase of the resultant voltage vector according to the pulsating component, the system optimizes the voltage utilization in over-modulation state. This parameter adjustment reduces unnecessary switching losses and improves overall device efficiency while maintaining high voltage utilization rate
3Device complexity
If a low-capacity smoothing capacitor is used instead of a high-capacity electrolytic capacitor, then device complexity reduces, but direct current link voltage pulsation increases causing motor failure
Solution Approach 1:
The controller implements feedback control by detecting the pulsating component of the direct current link voltage and adjusting the phase of the resultant voltage vector accordingly. This feedback mechanism compensates for the increased voltage pulsation caused by using a low-capacity smoothing capacitor, thereby maintaining motor operation stability without requiring a large electrolytic capacitor
Solution Approach 2:
The system changes the control parameter (phase of resultant voltage vector) to adapt to the conditions created by using a low-capacity smoothing capacitor. This parameter change compensates for the adverse effects of voltage pulsation, allowing the use of simpler capacitor components while maintaining reliable motor operation
Data Source
AI summary
In a power converter, vibration and noise of a motor due to pulsation of a direct current link voltage are reduced. An inverter circuit is provided, which is configured to convert a direct current link voltage having a pulsating component to an alternating current to output the alternating current to a permanent magnet synchronous motor. A controller is provided, which is configured to control the inverter circuit by vector control and which, in a control state in which fundamental voltage vectors do not include a zero vector (voltage vector for which a motor terminal voltage is zero), performs such control that the phase of a resultant voltage vector of a d-axis voltage vector and a q-axis voltage vector of the permanent magnet synchronous motor varies depending on pulsation.