Electromagnetic Valve Coil Hold Current Control Under Switching Noise
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Solution Overview
Problem
Existing electromagnetic valve drive devices face challenges in accurately limiting the fluctuation range of the hold current due to noise interference from chopper control switching elements, making it difficult to maintain a desired current range.
Innovation Solution
The implementation of a system that includes a power supplier, a detector, first and second comparators, a filter, and a control signal generator, utilizing a count-up/down type digital filter to control the power supplier and set maximum and minimum values of the hold current, along with a boost circuit to generate a boosted voltage for the electromagnetic coil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a boost circuit is used to drive the electromagnetic coil, then the electromagnetic valve can be driven with sufficient power, but switching noise from the chopper control switching element causes disturbance in the holding control
Solution Approach 1:
A low-pass filter is introduced as an intermediary component between the current detector and the control circuit. This filter mediates the signal transmission by allowing the hold current signal to pass through while blocking the high-frequency switching noise from the chopper control switching element, thus preventing noise disturbance in the holding control
Solution Approach 2:
The harmful switching noise component is extracted and removed from the signal path by the low-pass filter. The filter separates the useful hold current signal from the harmful high-frequency noise, allowing only the desired signal to reach the control circuit
2Device complexity
If simple current control is used, then the control circuit is simple, but the fluctuation range of hold current cannot be limited within desired range due to noise
Solution Approach 1:
A feedback control mechanism is implemented where the hold current is detected by a current detector, filtered to remove noise, compared against threshold values, and used to generate control signals that adjust the power supplier. This closed-loop feedback system ensures the hold current remains within the desired range despite noise interference
Solution Approach 2:
The system changes the parameter of signal frequency by using a low-pass filter to convert the noisy current signal into a clean control signal. The filter transforms the high-frequency noise into a low-frequency or DC signal that can be properly processed by the control circuit
3Loss of energy
If hold current is supplied intermittently, then energy consumption is reduced, but current ripple increases
Solution Approach 1:
The power supplier intermittently supplies hold current in periodic pulses rather than continuously. This periodic action reduces energy consumption while the low-pass filter smooths the resulting current ripple, maintaining current stability within acceptable ranges
Solution Approach 2:
The system changes the time parameter by controlling the duty cycle and frequency of intermittent current supply. By adjusting these temporal parameters and using filtering, the system achieves energy efficiency while maintaining current 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 limits the fluctuation range of the hold current within a desired range, improving accuracy and stability by using a digital filter to process noise and adjust the hold current accordingly.
Implementation Method 1
supplies electricity with a current peak... to an electromagnetic coil of an electromagnetic valve
Data Source
AI summary
An electromagnetic valve drive device which supplies a hold current with a prescribed fluctuation range to an electromagnetic coil of an electromagnetic valve after a current peak when a supply of electricity starts has passed includes: a power supplier which intermittently applies a drive voltage to the electromagnetic coil; a detector which detects the hold current; a first comparator which compares a detected current by the detector with a first threshold value; a filter which performs integration processing on an output of the first comparator; a second comparator which compares an output of the filter with a second threshold value to generate an output signal used for generating a control signal for controlling the power supplier; and a control signal generator which generates the control signal for controlling the power supplier based on the output signal of the second comparator, wherein the filter is a count-up/down type digital filter.