Emulated Current Generation Circuit for High-Frequency Power Conversion

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Solution Overview

Problem

Conventional current sensing circuits in high-frequency buck or boost power converting circuits fail to sense the inductor current waveform instantaneously, leading to deficiencies such as non-instantaneous sensing and high circuit costs and control difficulties.

Innovation Solution

An emulated current generation circuit that combines an AC component current and a DC component current, generated through a ramp signal and sample-and-hold processing respectively, to produce an emulated sensing current, with a calibration circuit dynamically adjusting the ramp signal to improve accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the system operating frequency is increased to improve productivity, then the switching speed increases, but the on-time of the switch becomes very short causing the conventional current sensing circuit to fail to sense the inductor current waveform immediately

Engineering Contradiction:

Improvesystem operating frequencyVSAvoidcurrent sensing accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent uses a sample-and-hold circuit to capture and hold the sensing current at the moment the switch turns off, before the current waveform changes. This preliminary action preserves the current state for subsequent processing, enabling accurate sensing even at high frequencies where the switch on-time is very short.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary emulated current generation circuit that combines the held sensing current with a ramp signal to reconstruct the complete inductor current waveform. This intermediary circuit bridges the gap between the brief sensing window and the full current waveform, enabling accurate current measurement at high operating frequencies.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If a sample-and-hold method is used to obtain the sensing current, then the circuit can operate at higher frequencies, but the sensing current waveform becomes non-instantaneous

Engineering Contradiction:

Improveswitching speedVSAvoidsensing current delay

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The sample-and-hold circuit performs preliminary capture of the sensing current at the critical moment of switch turn-off, storing this information for subsequent waveform reconstruction. This preliminary action enables the system to operate at high speeds while preserving the instantaneous current state for accurate emulation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent combines the held sensing current with a continuously generated ramp signal to reconstruct the complete current waveform continuously. This continuous reconstruction process eliminates the discontinuity introduced by sampling, maintaining the usefulness of the sensing action throughout the switching cycle.

Inventive Principle:

Principle #20Continuity of useful action

3Measurement precision

If a combination of partial emulated current and partial sensing current is used to obtain the complete current waveform, then the current sensing accuracy improves, but the circuit cost and control difficulty increase

Engineering Contradiction:

Improvecurrent waveform sensing accuracyVSAvoidcircuit cost and control difficulty

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the current waveform into two components: the sensing current (obtained through sample-and-hold) and the ramp signal (generated separately). By dividing the waveform reconstruction into these manageable segments, the circuit achieves accurate current sensing while keeping each component relatively simple and cost-effective.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges the held sensing current with the ramp signal in a combination circuit to reconstruct the complete inductor current waveform. This merging of two simple components achieves the complex function of full waveform sensing without requiring a complex sensing circuit, thereby reducing overall circuit cost and control difficulty.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11722058B2Emulated current generation circuit of power converting circuit and method thereof

Publication Date: 2023.08.08 UPI SEMICON CORP

AI summary

An emulated current generation circuit of a power converting circuit, providing an emulated current includes an AC component current and a DC component current, includes a first current circuit, a second current circuit, a combination circuit and a calibration circuit. The first current circuit generates a ramp signal as the AC component current. The second current circuit is coupled to an output stage of power converting circuit to provide a sensing current. The DC component current is generated after performing a sample-and-hold processing on the sensing current. The combination circuit is coupled to the first current circuit and second current circuit respectively to combine the AC component current and DC component current into an emulated sensing current. The calibration circuit is coupled to the first current circuit, second current circuit and combination circuit to dynamically adjust the ramp signal according to the emulated sensing current and sensing current.