Voltage Smoothing Circuit With Zener Diode Balancing

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Solution Overview

Problem

Existing voltage smoothing circuits face challenges in maintaining voltage balance across smoothing capacitors with variations in internal resistors, leading to potential overvoltage issues and increased heat emission due to large current flows through balancing resistors, which complicates the circuit configuration and increases costs.

Innovation Solution

A voltage smoothing circuit design that includes a balancing resistor in parallel with a smoothing capacitor and a conduction regulating element, such as a Zener diode, allowing current to flow through the resistor when voltages exceed predetermined levels, thereby controlling power loss and heat emission, and enabling the use of smaller, less expensive capacitors by adjusting the Zener voltage and balancing resistor values to maintain voltage balance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a balancing resistor is connected in parallel to smoothing capacitors to maintain voltage balance, then voltage balance between capacitors is improved, but large current flows through the resistor causing excessive heat emission and power loss

Engineering Contradiction:
Improvevoltage balanceVSAvoidpower loss
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent introduces a voltage-dependent resistance mechanism by connecting a resistor in series with a Zener diode across one of the smoothing capacitors. When the voltage across the capacitor exceeds the Zener voltage, the diode conducts and effectively changes the resistance value, allowing current to divert away from the balancing resistor and reducing power loss while maintaining voltage balance.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If a balancing resistor is used to maintain voltage balance across smoothing capacitors, then voltage balance is improved, but the circuit complexity and component specifications requirements increase

Engineering Contradiction:
Improvevoltage balanceVSAvoidcircuit configuration
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent uses a Zener diode as an intermediary element that activates only when voltage exceeds a predetermined threshold. This diode works in conjunction with a series resistor to create a voltage-dependent current diversion mechanism, adding minimal complexity while effectively controlling voltage balance and reducing power loss.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Stability of the object's composition

If a large current flows through the balancing resistor to maintain voltage balance, then voltage stability is improved, but heat emission increases affecting nearby electronic parts

Engineering Contradiction:
Improvevoltage stabilityVSAvoidheat emission
Core Design Contradiction:
Stability of the object's compositionVSTemperature

Solution Approach 1:

The patent creates a dynamic current distribution system where the path of least resistance changes based on voltage conditions. At normal operating voltages, the balancing resistor maintains voltage stability. When voltage rises above the Zener threshold, the diode conducts and dynamically redirects current away from the balancing resistor, reducing heat emission while preserving voltage stability through the Zener clamping effect.

Inventive Principle:
Principle #15Dynamics

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 effectively controls voltage across capacitors, reduces power loss and heat emission, and allows for the use of inexpensive capacitors, making the circuit more efficient and cost-effective while maintaining voltage balance across capacitors.

Implementation Method 1

a conduction regulating element, such as a Zener diode, allowing current to flow through the resistor when voltages exceed predetermined levels

Methodology Applied
Scientific EffectZener breakdown: Diode

Implementation Method 2

two smoothing capacitors are connected in series to each other and are connected in parallel to the power supply

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 3

a balancing resistor whose resistance value is smaller than those of internal resistors of the smoothing capacitors is connected in parallel to the smoothing capacitors

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2463998B1Voltage smoothing circuit
Publication Date: 2020.04.22 DAIKIN INDUSTRIES LTD
  • EP2463998B1 patent drawingFigure 1
  • EP2463998B1 patent drawingFigure 2
  • EP2463998B1 patent drawingFigure 3

AI summary

Even if there are variations between internal resistors of smoothing capacitors, to prevent with a simple configuration a voltage greater than the rated voltage of a smoothing capacitor from being applied to that capacitor. And to maintain with a simple configuration a balance between voltages applied to smoothing capacitors. A voltage smoothing circuit (14) is equipped with a first smoothing capacitor (C1), a second smoothing capacitor (C2), a balancing resistor (R3), and a Zener diode (RZ4). The first smoothing capacitor (C1) and the second smoothing capacitor (C2) are connected in series to each other and are connected in parallel to a power supply portion (13). The balancing resistor (R3) is connected in parallel to the first smoothing capacitor (C1). The Zener diode (RZ4) is connected on a current path (14) in parallel with the second smoothing capacitor (C2). The Zener diode (RZ4) conducts current in one direction on the current path (14) in a case where a voltage equal to or greater than a Zener voltage (Vr4) has been applied.