DC Tool Torque Control via Battery Voltage Detection and PWM Compensation

Solution Overview

Problem

Current DC electric tools lack the ability to automatically adjust torque output in response to decreasing battery voltage, leading to unpredictable performance and potential failure to deliver preset torque levels, affecting reliable operation.

Innovation Solution

A method that presets torque levels and corresponding voltage ranges, detects current battery voltage, and adjusts PWM values to maintain or compensate torque output, providing warnings when the voltage is insufficient to meet selected torque levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the DC electric tool uses fixed torque levels without voltage compensation, then the device complexity is reduced, but the torque output accuracy deteriorates when battery voltage decreases

Engineering Contradiction:

Improvecontrol system complexityVSAvoidtorque output accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The control system continuously detects the battery voltage and compares it with preset voltage thresholds. Based on the detected voltage level, the system automatically adjusts the PWM duty cycle to compensate for voltage drop, ensuring the torque output remains at the selected level. This closed-loop feedback mechanism resolves the contradiction by adding intelligent control that maintains torque accuracy without requiring complex mechanical adjustments.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system changes the PWM duty cycle parameter dynamically based on the detected battery voltage. When voltage drops below a threshold, the system increases the PWM duty cycle to compensate for the reduced voltage, thereby maintaining the desired torque output. This parameter adjustment strategy allows the system to adapt to varying battery conditions while keeping the overall device structure relatively simple.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the DC electric tool adds automatic voltage compensation function, then the torque output accuracy is improved, but the device complexity increases

Engineering Contradiction:

Improvetorque output accuracyVSAvoidcontrol system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The control system continuously detects the battery voltage and compares it with preset voltage thresholds. Based on the detected voltage level, the system automatically adjusts the PWM duty cycle to compensate for voltage drop, ensuring the torque output remains at the selected level. This closed-loop feedback mechanism resolves the contradiction by adding intelligent control that maintains torque accuracy without requiring complex mechanical adjustments.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control system automatically detects voltage drops and adjusts PWM parameters without user intervention. The system serves itself by monitoring its own power supply condition and making necessary corrections to maintain performance, eliminating the need for manual adjustments or complex external control mechanisms.

Inventive Principle:

Principle #25Self-service

3Ease of operation

If the DC electric tool uses simple speed levels without voltage detection, then the ease of operation is improved, but the reliability deteriorates when battery voltage decreases

Engineering Contradiction:

Improvetorque level selectionVSAvoidtorque output reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The control system continuously detects the battery voltage and compares it with preset voltage thresholds. Based on the detected voltage level, the system automatically adjusts the PWM duty cycle to compensate for voltage drop, ensuring the torque output remains at the selected level. This closed-loop feedback mechanism resolves the contradiction by adding intelligent control that maintains torque accuracy without requiring complex mechanical adjustments.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system replaces manual mechanical adjustment with electronic control. Instead of requiring users to mechanically adjust components to compensate for voltage drop, the system uses electronic PWM control to automatically adjust the motor output, maintaining reliability while preserving ease of operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Manufacturing precision

If the DC electric tool increases PWM value for compensation, then the torque output accuracy is improved, but the energy consumption increases

Engineering Contradiction:

Improvetorque output accuracyVSAvoidbattery energy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The system applies PWM compensation only when and where needed - specifically when the battery voltage drops below the preset threshold. The compensation is applied partially, adjusting only the extent necessary to maintain torque accuracy, rather than continuously maximizing PWM values. This selective application reduces unnecessary energy consumption while maintaining torque output accuracy when required.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The system changes the PWM duty cycle parameter dynamically based on the detected battery voltage. When voltage drops below a threshold, the system increases the PWM duty cycle to compensate for the reduced voltage, thereby maintaining the desired torque output. This parameter adjustment strategy allows the system to adapt to varying battery conditions while keeping the overall device structure relatively simple.

Inventive Principle:

Principle #35Parameter changes

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

Ensures accurate and consistent torque output, allowing users to better utilize the tool and preventing operational failures by automatically compensating for voltage-related torque reductions and providing timely warnings.

Implementation Method 1

The current DC electric tools mostly have an adjustable function for the torque output... detecting the current output voltage of a battery... driving a motor

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentUS9555527B2Method for controlling torque output of DC electric tool

Publication Date: 2017.01.31 CHERVON HK LTD WANCHAI

AI summary

A method for controlling a torque output of a DC electric tool, includes presetting torque levels and voltage ranges corresponding to the torque levels, detecting the current output voltage of a battery and determining the voltage range in which the current output voltage is located, determining whether or not the current voltage range matches the preset torque level or not, and if the current voltage range does not match the preset torque level providing a warning that the torque output cannot reach the preset torque level and calculating and displaying a maximum torque level corresponding to the actual torque output value and, if the current voltage range does match the preset torque level, calculating the current actual torque output value and keeping a PWM modulation value constant if the torque output value conforms to the preset torque level or increasing the PWM modulation value for compensation if the torque output value does not conform to the preset torque level.