Phase-Shifted Triangle Wave Circuit for Accurate High-Frequency PWM

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing triangle wave generating circuits fail to produce symmetrical triangle waves with phases shifted by 180°, leading to reduced accuracy in PWM control for multiple switching power supplies, especially when using asymmetrical triangle waves or high-frequency signals.

Innovation Solution

A triangle wave generating circuit comprising a pulse generating circuit and charge/discharge circuits that produce pulse signals with different phases, using current sources and switch circuits to charge and discharge capacitors at predetermined current values, ensuring symmetrical triangle waves with phases shifted by 180°, and capable of generating multiple triangle waves with varying phase shifts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If asymmetrical triangle waves or high-frequency signals are used in PWM control, then the switching frequency of power supplies can be increased, but the phase shift accuracy between multiple power supplies deteriorates

Engineering Contradiction:

Improveswitching frequencyVSAvoidphase shift accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The circuit segments the triangle wave generation into multiple independent charge/discharge paths, each controlled by separate pulse signals with different phases. This allows each path to operate independently at high frequency while maintaining precise phase relationships through synchronized control signals.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the control parameter from relying on operational amplifier response characteristics to using explicit phase-shifted pulse signals that directly control charge/discharge timing. This parameter change enables accurate phase control independent of signal frequency.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If a common triangle wave generating circuit is used to provide triangle waves to multiple switching power supplies, then the circuit complexity is reduced, but the phase shift accuracy between power supplies deteriorates

Engineering Contradiction:

Improvecircuit complexityVSAvoidphase shift accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The charge/discharge circuit is designed with multi-functionality to handle multiple phase-shifted triangle wave generations using a single circuit structure. The circuit accepts multiple phase-shifted pulse signals and generates corresponding triangle waves simultaneously, maintaining accuracy while avoiding the need for multiple separate circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If operational amplifiers are used to generate and invert triangle waves, then the circuit implementation is simplified, but the slew rate limitations cause waveform distortion at high frequencies

Engineering Contradiction:

Improvecircuit implementationVSAvoidwaveform accuracy

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention replaces the operational amplifier-based analog system with a pulse-controlled charge/discharge system using switches and current sources. This substitution eliminates slew rate limitations while maintaining circuit simplicity through standardized components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 accurate PWM control with multiple switching power supplies by generating symmetrical triangle waves with high frequency and phase shifts, improving power supply efficiency and reducing power consumption in electronic equipment.

Implementation Method 1

a current supply circuit configured to supply to a capacitor a first current for charging at a predetermined current value or a second current for discharging at a predetermined current value

Methodology Applied

Scientific EffectCapacitor charging and discharging: Capacitance

Data Source

PatentUS8030976B2Triangle wave generating circuit

Publication Date: 2011.10.04 SEMICON COMPONENTS IND LLC

AI summary

A triangle wave generating circuit comprising: a pulse generating circuit configured to generate a plurality of pulse signals with the same period and with phases different from one another; and a plurality of charge/discharge circuits configured to be supplied with the plurality of pulse signals, respectively, the plurality of charge/discharge circuits each including: a current supply circuit configured to supply to a capacitor a first current for charging at a predetermined current value or a second current for discharging at a predetermined current value; and a charge/discharge control circuit configured to switch between the first current and the second current when the pulse signals are supplied thereto and when a voltage across the capacitor reaches a predetermined reference voltage, the first current and the second current supplied from the current supply circuit to the capacitor.