Boost Chopper Voltage Regulation for Compact Power Conversion
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Solution Overview
Problem
Electric power conversion devices face efficiency issues due to wide conduction widths required for harmonic control, leading to increased current and costs, especially when using flux-weakening control, which affects motor and inverter efficiency.
Innovation Solution
An electric power conversion device with a boost chopper and multiphase inverter circuit, where the capacitor voltage has a pulse frequency twice that of the AC power source, allowing torque generation without significant current increase, and a boost chopper controller that adjusts the terminal voltage to reduce current during flux-weakening control, optimizing efficiency and reducing component capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large smoothing capacitor is installed to supply DC to the inverter circuit, then the DC voltage stability is improved, but the device volume and weight increase
Solution Approach 1:
The patent employs periodic switching action of the boost chopper circuit to regulate DC voltage. The switching element periodically connects and disconnects the reactor to the DC circuit, creating pulsed voltage regulation that maintains stable DC output without requiring large smoothing capacitors. This periodic control enables voltage stabilization through active management rather than passive energy storage.
Solution Approach 2:
The patent changes the operating parameters of the boost chopper circuit, specifically controlling the duty cycle of the switching element and the inductance of the reactor, to achieve voltage regulation. By adjusting these parameters dynamically, the system maintains stable DC voltage output while using a much smaller capacitor than conventional systems.
2Loss of energy
If a boost circuit with switching element is used to improve power factor and reduce harmonics, then the power factor is improved, but the device complexity increases
Solution Approach 1:
The boost chopper circuit serves multiple functions simultaneously: it acts as a power factor correction circuit, a harmonic suppressor, and a DC voltage regulator. By integrating these functions into a single circuit topology with shared components (reactor, switching element, capacitor), the patent improves power factor and reduces harmonics without proportionally increasing device complexity.
Solution Approach 2:
The patent combines the converter circuit and power factor correction functionality into an integrated boost chopper circuit. The same reactor and switching elements used for voltage conversion also perform power factor correction and harmonic suppression, merging multiple functions into a unified circuit design that reduces overall complexity compared to separate circuits.
3Loss of energy
If the conduction width of diode bridge circuit is widened to correct power factor, then the power factor is improved, but the current increases significantly
Solution Approach 1:
The patent employs dynamic control of the switching element to regulate the conduction width of the diode bridge circuit. Rather than using a fixed wide conduction width, the switching element dynamically adjusts the effective conduction period based on instantaneous voltage and current conditions, maintaining power factor correction while limiting excessive current increase.
Solution Approach 2:
The boost chopper controller monitors the DC voltage and switching conditions to regulate the switching element's operation. This feedback control ensures that the conduction width is optimized in real-time, achieving power factor correction without allowing current to increase excessively, as the controller adjusts switching timing based on actual circuit conditions.
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 enables efficient power supply to motors without increased current, reduces losses, and minimizes the need for large capacitors, enhancing the overall efficiency and reducing costs of electric power conversion devices.
Implementation Method 1
a boost chopper (15), which boosts a voltage of the AC power source (30)
Implementation Method 2
a capacitor (12a), which is connected between output terminals of the converter circuit (11)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electric power conversion device includes: a converter circuit (11) which includes a boost chopper (15); a capacitor (12a) which is connected between output terminals of the converter circuit (11); a boost chopper (15) which boosts a terminal voltage (vdc) of the capacitor (12a); a multiphase inverter circuit (13); and a boost chopper controller (16). In a case where the operation of the boost chopper (15) is continuously stopped, the capacitor (12a) has a capacitance allowing the terminal voltage (vdc) of the capacitor (12a) to have a pulse frequency twice as high as that of the AC power source (30). The multiphase inverter circuit (13) has an output power which is allowed to fluctuate in synchronization with a power source.