Zero-Crossing Switch Control for Optocoupler Timing Compensation
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Solution Overview
Problem
Existing control devices for bidirectional semiconductor switches in electromechanical actuators suffer from variability due to optocoupler dispersion, leading to potential malfunctions and load shutdowns due to time shifts in zero-crossing detection, which are influenced by component variability, temperature, and electrical or electromagnetic disturbances.
Innovation Solution
A control device for bidirectional semiconductor switches that includes elements for detecting zero-crossing instants using optocouplers, measuring supply signal values, and determining control instants based on delayed pulses to compensate for variability, using a processing circuit to emit control pulses synchronized with zero-crossing detection and a predetermined threshold, and incorporating phase shift capacitors for directional motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optocoupler is used to detect zero-crossing instant, then the control device can synchronize switch control with AC power signal, but the optocoupler variability causes time shifts in detection leading to switch malfunction
Solution Approach 1:
The patent applies preliminary action by measuring the actual zero-crossing instant of the AC power signal in advance using an optocoupler, storing this measurement, and then using it to compensate for future control timing. The control device pre-determines the time difference between the optocoupler's detected zero-crossing and the actual zero-crossing, then applies this compensation to subsequent control pulses, ensuring accurate switch timing despite optocoupler variability.
Solution Approach 2:
The patent implements feedback by continuously monitoring the AC power signal's zero-crossing instant through the optocoupler, comparing it with the actual zero-crossing, determining the time shift, and using this information to adjust and compensate the control pulse timing. This closed-loop feedback mechanism ensures that control timing remains accurate despite variations in optocoupler performance due to temperature, component dispersion, or electromagnetic disturbances.
2Ease of operation
If control pulses are emitted in synchronism with optocoupler rising edge, then switch control is simplified, but time shift causes switch to not remain closed between pulses resulting in load malfunction
Solution Approach 1:
The patent introduces an intermediary compensation mechanism between the optocoupler detection and the control pulse generation. Instead of directly using the optocoupler's rising edge to trigger control pulses, the system first measures the time shift between the optocoupler detection and the actual AC zero-crossing, then uses this information as a compensatory offset. This intermediary step ensures that control pulses are emitted at the correct timing relative to the actual AC signal, preventing switch malfunction while maintaining systematic control.
3Adaptability or versatility
If optocoupler is subjected to temperature and electromagnetic disturbances, then device operates in real-world conditions, but detection variability increases causing control inaccuracies
Solution Approach 1:
The patent employs feedback to continuously monitor and compensate for detection variability caused by temperature and electromagnetic disturbances. By repeatedly measuring the zero-crossing instant and comparing it with the actual AC signal zero-crossing, the system determines the time shift caused by environmental factors and applies real-time compensation to maintain accurate control timing despite adverse operating conditions.
Solution Approach 2:
The patent addresses parameter changes due to environmental factors by dynamically adjusting the control timing parameters based on measured variations. The system monitors changes in the optocoupler's detection characteristics caused by temperature and electromagnetic interference, and compensates by modifying the control pulse timing parameters accordingly, maintaining measurement precision across varying operating conditions.
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 ensures precise control of the switch, minimizing malfunctions and load shutdowns by compensating for optocoupler variability, ensuring reliable operation under varying conditions.
Implementation Method 1
an optocoupler configured to emit a rising edge or a falling edge on a logic input of a processing circuit when the alternating supply signal is substantially equal to zero
Implementation Method 2
control elements of the switch configured to emit control pulses on a control terminal of the switch following receipt of a control order from the electromechanical actuator, each pulse being adapted to place the switch in a closed state between two pulses
Data Source
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AI summary
The invention relates to a method and a control device (1) for a controlled switch (2) for an electromechanical actuator (ACT). The control device (1) comprises first determination elements (8) of a delay as a function of, on the one hand, a first primary instant at which the processing circuit (41) detects a rising or falling edge from an optocoupler (61, 62) when an alternating supply signal (U0) is substantially equal to zero, and on the other hand, a second primary instant at which a value measured by the measuring elements (7) reaches or exceeds a predetermined threshold value, and second determination elements (9) of a control instant of the switch, the control instant being determined from a first secondary instant of reception of the rising or falling edge of the optocoupler (61, 62) and the delay determined by the first determination elements (8).