Capacitor-Based PWM Voltage Doubler for Portable Motor Startup
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Solution Overview
Problem
Existing methods for powering electric devices in PWM mode, such as electric motors, often require higher voltages for startup than for normal operation, and existing voltage doublers are complex and bulky, making them unsuitable for portable devices.
Innovation Solution
A compact apparatus using a single capacitor and a switchable circuit assembly that connects the capacitor in parallel or series with the voltage source to generate a PWM signal with a pulse height twice that of the available source voltage, allowing for efficient voltage boosting without inductances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a traditional voltage doubler is used to generate higher voltage for motor startup, then the required voltage is achieved, but the device becomes complex and bulky with multiple components including inductances
Solution Approach 1:
The patent extracts and eliminates the inductance component from the traditional voltage doubler circuit, retaining only the essential capacitor elements. This extraction simplifies the circuit topology while maintaining the voltage doubling function, directly resolving the contradiction between achieving high voltage and reducing device complexity
Solution Approach 2:
The patent employs periodic switching of the capacitor between series and parallel configurations with the voltage source during PWM cycles. This periodic action enables voltage doubling during motor startup while allowing simplified operation during normal running conditions, achieving high voltage when needed without permanent circuit complexity
2Power
If a traditional voltage doubler with multiple components is used, then voltage boosting is achieved, but the device size increases making it unsuitable for portable devices
Solution Approach 1:
By removing inductances and other bulky components from the traditional voltage doubler design, the patent creates a compact circuit suitable for portable devices. The extracted simplified circuit maintains voltage boosting capability while dramatically reducing the volume occupied by magnetic components and interconnections
Solution Approach 2:
The patent merges the voltage source and capacitor into a unified switchable assembly where the capacitor can be configured in series or parallel with the voltage source. This merging eliminates the need for separate voltage boosting components, reducing overall device volume while maintaining voltage doubling capability for motor startup in portable applications
3Device complexity
If a single capacitor is used for voltage doubling, then component count is reduced, but the ability to provide continuous power may be limited
Solution Approach 1:
The patent uses periodic PWM switching to alternately charge the single capacitor in parallel with the voltage source and then discharge it in series configuration. This periodic charge-discharge cycle enables the single capacitor to deliver pulsed power sufficient for motor startup and acceleration, compensating for the limited continuous energy storage with efficient periodic energy transfer
Solution Approach 2:
The patent changes the operational parameters of the single capacitor by dynamically switching its configuration between series and parallel connections. This parameter change enables the same capacitor to serve dual functions: voltage doubling during startup pulses and normal operation during steady-state, effectively extending its functional duration without adding components
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
The solution enables efficient voltage boosting, reducing component count and size, making it suitable for portable devices while maintaining system stability and allowing for adaptive power delivery to meet varying load requirements.
Implementation Method 1
a (flying) capacitor (20)... in the first circuit configuration the capacitor (20) is connected in parallel to the voltage source (10) so as to be chargeable by the voltage source (10), and in the second circuit configuration the capacitor (20) is connected in series between the voltage source (10) and the output node (30)
Data Source
AI summary
An apparatus and a method for generating a pulse width modulated, PWM, voltage doubler signal is presented The apparatus comprises a voltage source, a capacitor, an output node, a switchable circuit assembly for connecting the voltage source, the capacitor and the output node, and a controller for the switchable circuit assembly which is adapted to be switchable between a first circuit configuration in which the capacitor is connected in parallel to the voltage source so as to be chargeable by the voltage source, and a second circuit configuration in which the capacitor is connected in series between the voltage source and the output node, and wherein the control means is adapted to control the switchable circuit assembly to switch to the first circuit configuration in the first period, and to switch to the second circuit configuration in the second period.