Bridge Circuit Switching Control for Counter-Voltage Reduction
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Solution Overview
Problem
Existing circuit arrangements for controlling electric motors in battery-operated small appliances, such as electric toothbrushes and shavers, face issues with large parasitic inductance in lithium-ion batteries, leading to significant counter-voltages due to rapid current changes, which can disrupt the supply voltage and require voltage smoothing capacitors.
Innovation Solution
A circuit arrangement with a control circuit that switches electronic switches in at least two steps, using a series connection of capacitors and resistors to manage the switching process, allowing for smooth current changes and minimizing counter-voltages, thereby eliminating the need for capacitors to smooth the battery voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electronic switches are controlled with rapid switching between high and low levels, then switching speed is improved, but counter-voltage increases due to large parasitic inductance of Li-ion battery
Solution Approach 1:
The control circuit performs preliminary action by first switching the electronic switch to an intermediate state (neither fully high nor fully low) before transitioning to the final state. This staged approach allows the current to change gradually, preventing large counter-voltages from the battery's parasitic inductance while still achieving effective switching control
Solution Approach 2:
The switching process is segmented into multiple stages: initial state, intermediate state(s), and final state. By dividing the switching transition into discrete steps with intermediate停留, the control circuit manages current change rates, avoiding sudden current changes that would generate harmful counter-voltages
2Stability of the object's composition
If voltage smoothing capacitors are added to stabilize battery voltage, then voltage stability is improved, but circuit complexity increases
Solution Approach 1:
The control circuit serves dual functions: it controls the electronic switch while simultaneously stabilizing the battery voltage through its switching strategy. By managing the switching transitions to prevent large counter-voltages, the control circuit inherently stabilizes the voltage supply to itself and other components, eliminating the need for separate voltage smoothing capacitors
Solution Approach 2:
The control circuit is designed with multi-functionality, performing both switch control and voltage stabilization tasks. This universal approach allows a single component to address multiple requirements, reducing the overall component count and circuit complexity while maintaining voltage stability
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 effectively reduces counter-voltages and allows direct power supply to a microcontroller, enhancing efficiency and reducing circuit complexity by ensuring stable voltage supply without the need for capacitors, while maintaining low circuit complexity.
Implementation Method 1
a Li-ion battery has a large parasitic inductance compared to other batteries, which induces a correspondingly large counter-voltage when the current changes
Data Source
Figure 1
AI summary
The invention relates to a circuit arrangement for controlling an electrical consumer (M), said arrangement being provided with a bridge circuit which comprises four electronic switches (V1, V2, V3, V4) and the consumer (M) which is arranged in the transversal leg of the bridge circuit, and a control circuit (uC) comprising control terminals for the four electronic switches. The control terminal for the first electronic switch (V1) is connected to the control terminal for the fourth electronic switch (V4) by means of a series connection consisting of a first capacitor (C1) and a first resistance (R1), and the control terminal for the third electronic switch (V3) is connected to the control terminal for the second electronic switch (V2) by means of a series connection consisting of a second capacitor (C2) and a second resistance (R2). The invention also relates to a method for switching an electronic switch by means of a control circuit (uC) comprising a control terminal for controlling the electronic switch which can either be switched ("tristate") as an input ("high impedance") or as an output ("low" or "high"). The switching of the electronic switch from the conductive state to the non-conductive state and/or vice versa is carried out in two steps, namely the control terminal is switched from "low" via "high impedance" to "high" or from "high" via "high impedance" to "low".