Thyristor Diode Mode Triggering via Self-Powered Circuit
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Solution Overview
Problem
Existing methods for controlling thyristors in a rectifier bridge require synchronization with the supply network, which can be problematic during dynamic changes or faults, and involve complex components that are costly and difficult to scale.
Innovation Solution
A method and circuit that uses a feedforward circuit with a trigger capacitor and zener diode to directly trigger thyristors based on anode-cathode voltage, eliminating the need for network synchronization and using few, non-magnetic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronization with the supply network is used for controlling thyristors, then reliable triggering can be achieved, but the device complexity and cost increase due to phase lock circuits and auxiliary voltages
Solution Approach 1:
The invention extracts and eliminates the synchronization function from the control system. Instead of using phase lock circuits and auxiliary voltages to synchronize with the supply network, the circuit directly uses the instantaneous anode-cathode voltage of the thyristor itself to trigger it, removing the need for complex synchronization equipment while maintaining reliable triggering in diode mode
Solution Approach 2:
The thyristor triggers itself by utilizing its own anode-cathode voltage. The capacitor charges from the thyristor's anode-cathode voltage and automatically triggers the thyristor when the voltage becomes positive, eliminating the need for external synchronization signals or auxiliary power supplies
2Reliability
If magnetic components and integrated circuits are used in the triggering circuit, then reliable control can be achieved, but the cost increases and scalability to multiple power levels becomes difficult
Solution Approach 1:
The invention replaces expensive magnetic components and integrated circuits with simple, inexpensive passive components (capacitor, zener diode, resistors) that can be easily manufactured and scaled. The circuit uses basic electronic components that are cheap and can be replicated across different power levels without requiring complex or expensive parts
Solution Approach 2:
The triggering function is segmented into simple functional blocks: voltage detection (anode-cathode voltage), energy storage (capacitor), voltage regulation (zener diode), and triggering (gate current). Each function is performed by a simple component, making the overall system easier to manufacture and scale to different power levels
3Adaptability or versatility
If phase lock circuits are used for synchronization, then dynamic changes in the network can be tracked, but the device complexity and cost increase
Solution Approach 1:
The circuit automatically adapts to dynamic network changes by directly responding to the instantaneous anode-cathode voltage of the thyristor. When the voltage becomes positive, the capacitor charges and triggers the thyristor without requiring any synchronization circuitry to track or respond to network dynamics
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 simplifies thyristor triggering in diode mode, is tolerant to network dynamics, and reduces costs by avoiding auxiliary voltages and magnetic components, enabling reliable operation without synchronization.
Implementation Method 1
a zener diode V5 connected in parallel with the capacitor C2, the cathode of the zener diode V5 being connected to one end of the capacitor C2
Implementation Method 2
a capacitor C2 connected between the positive rail Udc+ of the voltage intermediate circuit and a supply line L1 of an alternating voltage source
Data Source
AI summary
A method and a circuit for controlling a thyristor (V1) into conducting state, the thyristor (V1) being in a rectifier, which rectifier supplies DC voltage to a DC voltage circuit. The circuit comprising a trigger capacitor (C2) adapted to be charged from the voltage difference across the thyristor (V1) when the anode-to-cathode voltage of the thyristor is positive, a zener diode (V5) adapted to be triggered with the voltage of the trigger capacitor (C2), when the voltage of the trigger capacitor (C2) exceeds the breakdown voltage of the zener diode (V5), and an auxiliary thyristor (V3) adapted to be triggered with the current from the trigger capacitor (C2) flowing via the zener diode (V5), wherein the cathode of the auxiliary thyristor (V3) is connected to the gate of the thyristor (V1) for triggering the thyristor (V1) with the current from the trigger capacitor (C2) flowing via the auxiliary thyristor (V3) for using the thyristor (V1) in a diode mode.