Inductor Coil Driver Circuit for Keyless Access Systems
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Solution Overview
Problem
Conventional quasi-resonant oscillating circuit drivers for inductive antennas in keyless vehicle access and start-up systems face challenges in balancing low current consumption, data transmission rate, complexity, and compliance with radio licensing and electromagnetic compatibility (EMC) regulations, while also being costly and complex.
Innovation Solution
A driver circuit for an inductor coil with a first capacitor, two input paths for a positive reference voltage, two output paths for the inductor coil, and controllable switches, along with a current measuring device and switch control device, which reduces circuit and calibration complexity, current consumption, and interference signal emissions, while ensuring compliance with radio licensing regulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a high quality level is used in the oscillating circuit to restrict energy consumption, then current consumption is reduced, but data transmission rate is restricted
Solution Approach 1:
The driver circuit uses periodic switching of the controllable switches to periodically charge and discharge the capacitor through the inductor coil, creating oscillating current pulses that transmit data. This periodic action allows the system to achieve sufficient data transmission rates while maintaining low average current consumption by keeping the oscillating circuit inactive between transmission periods.
2Use of energy by moving object
If accurate frequency tuning is applied to achieve low current consumption, then energy consumption is reduced, but circuit complexity increases
Solution Approach 1:
The driver circuit achieves frequency tuning by changing the switching timing parameters of the controllable switches rather than using complex analog tuning circuits. The control device adjusts the duration and timing of switch activation to tune the oscillating frequency, simplifying the circuit while maintaining accurate frequency control for low current consumption.
3Use of energy by moving object
If quasi-resonant oscillating circuit drivers are used to achieve low current consumption and sufficient data transmission rate, then energy efficiency is improved, but compliance with radio licensing regulations is not achieved
Solution Approach 1:
The invention extracts and eliminates the problematic continuous oscillating component from the quasi-resonant driver circuit by using periodic switching to generate only the necessary transmission pulses. This removes the continuous electromagnetic radiation that violates radio licensing regulations while preserving the energy-efficient oscillating operation during active transmission periods.
4Reliability
If known quasi-resonant oscillating circuit drivers are designed to be surge-proof, then reliability is improved, but circuit complexity and costs increase
Solution Approach 1:
The driver circuit incorporates surge protection by beforehand cushioning against voltage spikes and current surges through proper switch configuration and timing. The controllable switches are designed to open and close in sequences that prevent dangerous voltage buildup, and the circuit includes protective elements positioned to cushion against surges before they can damage sensitive components, achieving reliability without excessive complexity.
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 achieves reduced circuit and calibration complexity, lower current consumption, and reduced interference signal emissions, while allowing compliance with radio licensing regulations, thereby improving the efficiency and cost-effectiveness of the vehicle access and start-up system.
Implementation Method 1
a first capacitor (4), two input paths for the routing of a positive reference voltage (Ur) for the first capacitor (4)
Implementation Method 2
thereafter to open the first switch and close the second and fourth switches, such that the first capacitor (4) is discharged in an oscillating manner via the inductor coil (2)
Implementation Method 3
a current measuring device (8), which is connected between the fourth controllable switch (14) and the first capacitor (4), and is designed for the measurement of a current (Ia) flowing in the inductor coil (2)
Data Source
AI summary
Driver circuit in which a capacitor (4), in a manner controlled by a switch control device (9) which is connected downstream of a current measuring device (8), is charged to a reference voltage (Ur) by means of a charging current (Ic2), and the charged capacitor is discharged in an oscillating manner via an inductor coil (1), wherein the discharging operation is terminated when the current (Ia) through the inductor coil has passed through an entire oscillation period or several oscillation periods, wherein a first controllable switch (5) is connected in series between a first non-reactive resistor (6) and the first capacitor (4) in one of two input paths. Furthermore, a second controllable switch (7) and a fourth controllable switch (14) are connected into two output paths, and a second non-reactive resistor (13) is connected between a second connection (X2) of the inductor coil (1) and a connection for a reference potential (Um). The current measuring device (8) is connected between the fourth controllable switch (14) and the first capacitor (4).