Method for driving electric motors using a pulse-width-modulated signal
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Solution Overview
Problem
Existing methods for reducing radio interference from pulse-width-modulated electric motors are ineffective across a wide frequency spectrum, requiring knowledge of a specific carrier frequency and being costly and space-intensive, while also failing to address interference from multiple technical systems simultaneously.
Innovation Solution
The PWM frequency is dynamically adjusted within a predefined or random scheme without changing the duty cycle, allowing the interference power to be distributed across a broad frequency range, thereby minimizing interference and exceeding limit values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If filters (capacitors and coils) are used to reduce radio interference, then interference reduction is achieved, but device complexity, cost, and installation space increase
Solution Approach 1:
The invention extracts and eliminates the need for external filtering components (capacitors and coils) by implementing interference suppression directly at the PWM signal generation stage through frequency modulation, thereby removing harmful elements from the system
Solution Approach 2:
The invention replaces the mechanical/electrical filtering system (capacitors and coils) with a signal processing approach using frequency modulation of the PWM signal, substituting physical filtering components with electronic control methods
2Object-affected harmful factors
If PWM frequency is changed dynamically, then interference is distributed across a broad frequency range reducing peak interference, but control complexity increases
Solution Approach 1:
The invention applies dynamics by making the PWM frequency variable rather than constant, modulating it around a center frequency to spread interference energy across a broader spectrum, thereby reducing peak interference levels without requiring complex control mechanisms
Solution Approach 2:
The invention uses periodic frequency modulation of the PWM signal, where the frequency varies periodically around a center frequency according to a modulation signal, effectively distributing interference energy over time and frequency
Data Source
AI summary
A method for driving electric motors using a pulse-width-modulated signal, wherein the pulse-width-modulated signal is a square-wave pulse consisting of successive pulses whose impulse duration is adjustable, as a result of which it is possible to change a duty cycle, which is the ratio of the impulse duration and the period of the square-wave pulse, wherein the reciprocal of the period of the square-wave pulse is the PWM frequency at which the impulses follow one another, wherein, during operation of the electric motor, the PWM frequency within a frequency band, without the duty cycle changing, is changed repeatedly and in accordance with a predefined scheme or randomly.