Motor-Driven Compressor Voltage Detection Circuit

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Solution Overview

Problem

Existing motor-driven compressor systems for vehicles experience increased power consumption due to constant current flow through voltage divider resistors in power supply control devices, leading to inefficient battery usage.

Innovation Solution

A motor-driven compressor system that includes an AD conversion circuit to convert analog ignition voltage to digital signals, allowing the control device to determine overvoltage or low-voltage states without relying on voltage divider resistors, thereby reducing power consumption by controlling the switching element to apply or remove the ignition voltage from the detection circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If voltage divider resistors are used to detect ignition voltage, then voltage detection is enabled, but power consumption increases due to constant current flow

Engineering Contradiction:

Improveignition voltage detectionVSAvoidbattery power consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic sampling of the ignition voltage through the ECU rather than continuous monitoring. The AD conversion circuit converts the analog ignition voltage to digital signals periodically, and the ECU determines overvoltage or low-voltage states at discrete intervals. This periodic action eliminates the need for continuous current flow through voltage divider resistors, significantly reducing battery power consumption while maintaining adequate voltage detection capability.

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If voltage divider resistors are used for voltage detection, then voltage measurement is achieved, but the number of circuit components increases

Engineering Contradiction:

Improvevoltage detection capabilityVSAvoidnumber of circuit components

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the voltage divider resistors from the detection circuit. Instead of using the traditional voltage division method with multiple resistors, the system directly applies the ignition voltage to the AD conversion circuit's analog input terminal. This extraction removes unnecessary components while maintaining the essential voltage detection function through digital conversion and software-based threshold comparison.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the passive electrical component-based voltage division system with an active digital conversion and processing system. The AD conversion circuit converts the analog ignition voltage signal to digital signals, and the ECU uses software logic to determine voltage states by comparing digital values against predetermined thresholds. This substitution eliminates the need for voltage divider resistors and reduces overall circuit complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If continuous voltage monitoring is implemented, then real-time voltage state detection is achieved, but power consumption increases

Engineering Contradiction:

Improvereal-time voltage state detectionVSAvoidbattery power consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system implements periodic sampling of the ignition voltage at predetermined intervals rather than continuous monitoring. The ECU determines overvoltage or low-voltage states by comparing digitally converted voltage values against predetermined thresholds at discrete time points. This periodic approach maintains real-time voltage state detection capability while significantly reducing power consumption by keeping the detection circuit inactive between sampling intervals.

Inventive Principle:

Principle #19Periodic action

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 solution reduces power consumption by eliminating the need for voltage divider resistors, enhances measurement accuracy, allows for easier threshold value adjustments, and decreases the number of insulating elements required, thereby minimizing noise and power loss while reducing inrush currents and the size of fuses.

Implementation Method 1

an AD conversion circuit configured to convert the on-voltage from an analog signal to a digital signal

Methodology Applied

Scientific EffectAnalog-to-digital conversion:

Implementation Method 2

a switching element located at an on-voltage input side of the AD conversion circuit, and a switch configured to turn on the switching element when receiving a wake-up signal

Methodology Applied

Scientific EffectElectrical switching:

Data Source

PatentUS20240052819A1Motor-driven compressor for vehicle

Publication Date: 2024.02.15 TOYOTA INDUSTRIES CORP

AI summary

A motor-driven compressor for a vehicle includes a control device and a detection circuit. The detection circuit includes an AD conversion circuit. The AD conversion circuit converts an on-voltage from an analog signal to a digital signal. The control device is configured to determine that a battery is in an overvoltage state and stop the motor-driven compressor for the vehicle when a value of the on-voltage detected from the digital signal is larger than an overvoltage determination threshold value.