Electrolytic Capacitor-Less Inverter for Laundry Machine Motor Control
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Solution Overview
Problem
Laundry treating machines with inverter-based systems face challenges due to the high cost and bulkiness of power factor corrector units, which are necessary to manage harmonics and ripple voltage, affecting motor performance and mains current.
Innovation Solution
A laundry treating machine design that eliminates the need for electrolytic capacitors by using an electrolytic capacitor-less inverter with a DC-link capacitor and an active voltage limiter unit to regulate duty cycles and limit DC-link capacitor voltage, thereby reducing harmonic content and eliminating the power factor corrector unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power factor corrector unit is used to manage harmonics and ripple voltage, then motor performance is improved, but the machine becomes bulkier and more expensive
Solution Approach 1:
The invention extracts and eliminates the power factor corrector unit from the inverter system. By using a DC-link capacitor with sufficient capacitance value, the system naturally manages harmonics and ripple voltage without requiring the separate power factor corrector component, thereby reducing machine bulkiness while maintaining motor performance
Solution Approach 2:
The DC-link capacitor is designed to serve multiple functions simultaneously: it smooths rectified voltage, manages ripple voltage, and provides power factor correction. This multi-functionality eliminates the need for separate power factor corrector units, reducing both cost and bulkiness while maintaining motor performance
2Reliability
If a power factor corrector unit is used to manage harmonics and ripple voltage, then motor performance is improved, but the machine cost increases
Solution Approach 1:
The invention extracts and eliminates the power factor corrector unit from the inverter system. By using a DC-link capacitor with sufficient capacitance value, the system naturally manages harmonics and ripple voltage without requiring the separate power factor corrector component, thereby reducing machine bulkiness while maintaining motor performance
Solution Approach 2:
The DC-link capacitor is designed to serve multiple functions simultaneously: it smooths rectified voltage, manages ripple voltage, and provides power factor correction. This multi-functionality eliminates the need for separate power factor corrector units, reducing both cost and bulkiness while maintaining motor performance
3Ease of operation
If an electrolytic capacitor is used to reduce ripple voltage, then motor drive performance is improved, but the machine becomes bulkier
Solution Approach 1:
The invention changes the capacitance parameter of the DC-link capacitor to a sufficient value that naturally reduces ripple voltage to acceptable levels. By optimizing this single parameter, the system achieves good motor drive performance without requiring additional bulkiness from power factor corrector units or larger capacitor designs
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 reduces the machine's bulkiness and cost, improves motor performance by minimizing ripple voltage, and effectively manages harmonics without the need for a power factor corrector unit, enhancing overall efficiency and longevity.
Implementation Method 1
a DC-link capacitor connected to said DC-link
Implementation Method 2
an inverter-based apparatus which is configured to control said electric motor and comprises: an input stage which is connected to mains lines for receiving AC lines currents and AC mains voltage and configured to convert said alternating mains voltage AC to a rectified DC voltage
Data Source
AI summary
A laundry machine having a casing, a drum a motor to rotate the drum, and an inverter-based apparatus to control the motor. The inverter-based apparatus comprises: an input stage configured to convert alternating mains voltage to rectified DC voltage, an electrolytic capacitor-less inverter configured to generate output currents to feed to the electric moto based on duty cycles of switching signals, a DC-link connecting the electrolytic capacitor-less inverter to the input stage and crossed by DC-link currents from/towards the electrolytic capacitor-less inverter, a DC-link capacitor connected to the DC-link, a regulator system configured to control duty cycles of switching signals based on determined/estimated motor values indicating a controlled parameter of said motor, and a motor reference value associated to the controlled parameter of the motor, and an active voltage limiter unit configured to regulate the motor reference value to limit the DC-link capacitor voltage within a predetermined voltage range.