Power Conversion Apparatus with Regenerative Rectifier Circuits
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Solution Overview
Problem
Conventional power conversion apparatuses face challenges in suppressing energy loss and reducing size, particularly in multilevel conversion systems where parasitic inductance and surge voltage issues lead to increased switching losses and larger apparatus sizes.
Innovation Solution
The power conversion apparatus employs a configuration with upper and lower arms, capacitor units, and regenerative rectifier circuits to discharge energy stored in capacitors, using DC/DC converters to regenerate and manage energy efficiently, thereby reducing energy loss and apparatus size without increasing switching speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If switching speed is increased to reduce switching loss, then switching loss is suppressed, but parasitic inductance causes larger surge voltage
Solution Approach 1:
A snubber circuit is introduced as an intermediary component between the switching element and the load. This snubber circuit includes a snubber capacitor connected in parallel with the switching element and a snubber resistor connected in series with the snubber capacitor. The snubber circuit acts as a mediator that suppresses surge voltage generated by parasitic inductance during switching operations, enabling high-speed switching without excessive surge voltage while reducing switching loss.
Solution Approach 2:
The invention converts the harmful surge voltage energy into beneficial stored energy in the snubber capacitor. During switching, the surge voltage charges the snubber capacitor, storing energy that would otherwise be wasted. The snubber resistor then dissipates this energy in a controlled manner, preventing damage while maintaining switching performance.
2Loss of energy
If diode clamp type or flying capacitor type multilevel conversion is used to reduce switching loss, then switching loss is reduced, but parasitic inductance increases causing larger surge voltage
Solution Approach 1:
The power conversion apparatus is divided into multiple independent modules, each containing switching elements with their own snubber circuits. This segmentation allows each module to independently manage its surge voltage and switching loss, enabling multilevel conversion without increasing overall parasitic inductance. Each module operates autonomously with localized energy management through regenerative rectifier circuits.
Solution Approach 2:
The invention changes the electrical parameters by introducing regenerative rectifier circuits that convert the frequency of capacitor current to match the switching frequency. This parameter transformation allows the snubber capacitors to effectively suppress surge voltage while enabling energy regeneration, resolving the contradiction between reduced switching loss and increased parasitic inductance in multilevel configurations.
3Object-affected harmful factors
If modular type multilevel conversion apparatus is used to avoid increased parasitic inductance, then surge voltage is controlled, but DC capacitor size increases causing larger apparatus size
Solution Approach 1:
The invention recovers energy that would otherwise be discarded in the DC capacitor by introducing regenerative rectifier circuits. These circuits detect the frequency of capacitor current and convert it to switching frequency, enabling the snubber capacitors to regenerate energy back to the system. This energy recovery reduces the burden on the DC capacitor, allowing smaller capacitor sizes and reduced apparatus volume while maintaining surge voltage control.
Solution Approach 2:
The regenerative rectifier circuits implement feedback control by monitoring the capacitor current frequency and adjusting the switching frequency accordingly. This feedback mechanism optimizes the operation of snubber capacitors to effectively suppress surge voltage while minimizing the energy storage requirements of DC capacitors, thereby reducing overall apparatus size.
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 configuration effectively suppresses energy loss and avoids size increases by regenerating energy in capacitors, improving efficiency and reducing switching losses, while maintaining the same switching speed as conventional two-level inverters.
Implementation Method 1
the frequency of capacitor current is converted to switching frequency by a regenerative rectifier circuit
Implementation Method 2
the snubber circuit to absorb energy of the surge voltage generated by increasing the switching speed
Implementation Method 3
using DC/DC converters to regenerate and manage energy efficiently
Data Source
AI summary
An apparatus according to an embodiment includes an upper and lower arm connected between a high and a low potential end; a first capacitor connected at one end to the high potential end; a second capacitor connected at one end to the low potential end; a first regenerative rectifier circuit connected to another end of the first capacitor; a second regenerative rectifier circuit connected to another end of the second capacitor; a first conversion circuit to cause energy stored in the first capacitor to be discharged; and a second conversion circuit to cause energy stored in the second capacitor to be discharged.