Inductive Load Control Circuit for Regenerative Current Detection
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Solution Overview
Problem
Existing electromagnetic inductive load control devices face high production costs due to the need for high-speed diodes and voltage drop circuits to detect regeneration current and prevent EMI, while also generating pulsed currents that cause noise during PWM control.
Innovation Solution
An electromagnetic inductive load control device using a series circuit with a high-impedance surge-voltage absorption resistor and a low-impedance regenerative-current detection resistor, connected to the lower side of the inductive load, allowing regenerative current to flow to ground, eliminating the need for high-speed diodes and reducing noise by preventing high-frequency components in discharge current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-speed diode and voltage drop circuit are used to detect regeneration current, then the detection accuracy is improved, but the production cost increases
Solution Approach 1:
The patent extracts the harmful high-voltage component from the regeneration current detection circuit by using a potential division circuit. Instead of directly detecting the full regeneration current voltage, only a divided portion is detected, eliminating the need for expensive high-voltage protection circuits and high-speed diodes while maintaining detection accuracy.
Solution Approach 2:
The patent introduces a potential division circuit as an intermediary between the regeneration current source and the detection circuit. This intermediary circuit divides the high voltage into a lower, safer voltage level for detection, protecting the detection circuit from high voltage damage without requiring expensive high-voltage components.
2Use of energy by moving object
If PWM control is used to reduce power consumption, then energy efficiency is improved, but noise generation increases due to pulsed current
Solution Approach 1:
The patent converts the harmful pulsed current generated during PWM control into a beneficial continuous current by using a regenerative current circulation path. The regeneration current that would normally be wasted or cause noise is instead circulated through the load, maintaining continuous current flow and eliminating noise while preserving PWM energy efficiency.
3Device complexity
If regenerative current is allowed to flow through shunt resistor via diode, then current detection is simplified, but high voltage damages detection circuit
Solution Approach 1:
The patent introduces a potential division circuit as an intermediary between the regeneration current source and the detection circuit. This intermediary circuit divides the high voltage into a lower, safer voltage level for detection, protecting the detection circuit from high voltage damage without requiring expensive high-voltage components.
Solution Approach 2:
The patent extracts the harmful high-voltage component from the regeneration current detection circuit by using a potential division circuit. Instead of directly detecting the full regeneration current voltage, only a divided portion is detected, eliminating the need for expensive high-voltage protection circuits and high-speed diodes while maintaining detection accuracy.
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 allows for simple detection of regenerative current and suppression of noise during operation, reducing production costs and maintaining constant discharge current, thus minimizing EMI.
Implementation Method 1
a series circuit having a high-impedance surge-voltage absorption resistor and a low-impedance regenerative-current detection resistor
Implementation Method 2
during a power-off period of PWM control where the power supply from the power source to the electromagnetic inductive load is turned off, regeneration current flows
Data Source
Figure 1
Figure 2
Figure 3(a)~3
AI summary
With a relay control device (1) according to an embodiment, a regenerative current from a relay coil (5b) which is disposed in a relay (5) flows through a coil energy absorption circuit (7), which is connected to the low side of the relay coil (5b), toward the ground. A current detection resistor (Rsens), which is a shunt resistor, is connected further toward the ground side of the coil energy absorption circuit (7) than a coil surge absorption resistor (Rsup), and the potential (Vsens) of the current detection resistor (Rsens) is compared to a reference potential (Vref), with a current detection circuit (13). Furthermore, on the basis of the result of the comparison with the current detection circuit (13), an off-duty period of the PWM control is terminated before the current (Icoil) which flows through the relay coil (5b) becomes less than or equal to a minimum drive current (Iset).