Motor Driving Circuit with Adjustable Duty Cycle Slope
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Solution Overview
Problem
The existing electric motor driving circuits face limitations in flexibility and cost due to fixed relations between input and output duty cycles, requiring careful design of high voltage levels and large voltage sources, which increases component count and device size.
Innovation Solution
A driving circuit with a duty cycle to digital converter, slope setting pin, and digital pulse width modulator allows for adjustable relations between input and output duty cycles, reducing cost and area by using a duty cycle computation unit to generate controlling pulses based on input duty cycles and slope settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed relation between input and output duty cycles is used in the driving circuit, then the circuit design is simplified, but the flexibility and adaptability of the system is reduced
Solution Approach 1:
The patent implements a dynamic relationship between input and output duty cycles through a slope setting unit. The slope value can be changed to adjust the proportionality relationship, allowing the output duty cycle to adaptively scale with the input duty cycle. This resolves the contradiction by providing both a defined relationship (simplifying design) and adjustability (maintaining flexibility).
Solution Approach 2:
The patent changes the parameter of the duty cycle relationship by introducing a slope parameter that can be adjusted. The slope setting unit allows modification of the proportionality factor between input and output duty cycles, enabling the system to adapt to different operating conditions while maintaining a systematic design approach.
2Reliability
If high voltage levels and large voltage sources are used to ensure proper PWM signal generation, then the reliability of motor control is improved, but the cost and device area increase
Solution Approach 1:
The patent replaces the need for high voltage sources with a digital processing approach. By using a duty cycle to digital converter and digital pulse width modulator, the system processes PWM signals in the digital domain, eliminating the requirement for large analog voltage sources while maintaining control reliability through precise digital manipulation of duty cycle values.
Solution Approach 2:
The patent introduces digital signal processing components as intermediaries between the input PWM signal and the motor control output. The duty cycle to digital converter and digital pulse width modulator act as mediators that transform the control signal into the appropriate format without requiring high voltage sources, thus reducing cost and area while preserving reliability.
Data Source
AI summary
A driving circuit of an electric motor includes: a PWM input pin for externally receiving an input pulse modulation signal with an input duty cycle; a duty cycle to digital converter for receiving and converting the input pulse modulation signal into a first digital value; a slope setting pin for receiving information indicative of a slope of an output duty cycle corresponding to the input duty cycle; a slope acquisition unit for acquiring a second digital value corresponding to the information indicative of the slope; a duty cycle computation unit for generating a linearly increased duty cycle instruction value corresponding to the first digital value by referring to the slope; a digital pulse width modulator for generating a controlling pulse having the output duty cycle corresponding to the duty cycle instruction value; and an output circuit for driving the electric fan motor in accordance with the controlling pulse.