Thyristor Rectifier Bridge Control Without Galvanic Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional thyristor rectifier bridges require complex and costly galvanic isolation or optocoupler-based solutions for control signal application due to the cathode reference potential configuration, increasing production costs and complexity.
Innovation Solution
A controllable rectifier bridge design using anode gate thyristors with a control stage comprising transistors and resistive elements, allowing direct application of control signals without the need for isolation, by generating a negative potential using a charge pump circuit and connecting thyristor anodes to a common potential defined by positive and negative voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional thyristor rectifier bridges use cathode gate thyristors with cathodes connected to positive potential, then the rectifier bridge can be controlled, but complex and costly galvanic isolation or optocoupler-based solutions are required for control signal application
Solution Approach 1:
The patent inverts the conventional thyristor configuration by using anode gate thyristors instead of cathode gate thyristors. In this inverted configuration, the gate is connected to the anode rather than the cathode, which fundamentally changes the control mechanism. This inversion allows the control signal to be applied directly to the anode of the thyristor, eliminating the need for complex galvanic isolation or optocoupler-based solutions that are required in conventional cathode gate configurations.
Solution Approach 2:
The patent extracts and removes the complex galvanic isolation and optocoupler components from the control circuitry. By using anode gate thyristors, the control signal can be directly coupled to the thyristor gate through simple resistors, completely taking out the need for isolation transformers, optocouplers, and associated complex circuitry that would otherwise be required to safely apply control signals in conventional configurations.
2Ease of manufacture
If conventional thyristor rectifier bridges are designed with standard control configurations, then they can function as rectifiers, but they become expensive and difficult to control directly from a microcontroller
Solution Approach 1:
By inverting the thyristor configuration to use anode gate thyristors, the control interface is fundamentally simplified. The control signal from a microcontroller can be directly applied to the anode gate junction through a simple series resistor, making the device easy to manufacture and control without requiring complex isolation circuitry or specialized control interfaces.
Solution Approach 2:
The patent introduces a simple resistor as an intermediary element between the microcontroller output and the thyristor gate. This resistor serves as the only necessary component to limit the gate current and enable direct digital control, replacing the need for complex isolation transformers, optocouplers, or other intermediary devices that would otherwise be required in conventional configurations.
3Device complexity
If anode gate thyristors are used with a simplified control stage, then the circuit production is simplified and costs are reduced, but a negative potential must be generated relative to the rectified voltage terminal
Solution Approach 1:
The patent extracts the negative potential generation function into a separate, dedicated charge pump circuit that is independently powered from the rectified output voltage. This charge pump circuit uses simple switched capacitors to generate the required negative voltage, completely taking out the need for complex voltage reference circuits, precision resistive dividers, or other complicated potential generation schemes that would otherwise be required.
Solution Approach 2:
The charge pump circuit is self-powered from the rectified output voltage it helps to control, using the output voltage itself to drive the pumping action. This self-service approach eliminates the need for external power supplies or complex voltage reference sources, making the overall system easier to manufacture while still providing the required negative potential for control signal application.
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
Simplifies the production and reduces costs by eliminating the need for optocoupler or transformer-based isolation, enabling direct control signal processing and reducing production expenses.
Implementation Method 1
a charge pump circuit to generate a negative potential
Implementation Method 2
a first transistor coupling the gate of the thyristor to a terminal for supplying a negative potential
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
The invention relates to a rectifying circuit comprising: between a first terminal (23, 24) for applying an alternating voltage (Vac) and a first terminal (21) for supplying a rectified voltage (Vout), at least a first diode (D3, D4); between a second terminal (24, 23) for applying the alternating voltage and a second terminal (22) for supplying the rectified voltage, at least one first thyristor (TH1, TH2) with an anode gate, the anode of the first thyristor being connected to the second terminal (22) supplying the rectified voltage; and at least one first stage (4, 5) for controlling the first thyristor (TH1, TH2), comprising: a first transistor coupling the gate of the thyristor to a terminal (26) for supplying a negative potential (-Vdd) with respect to the potential of the second terminal (22) supplying the rectified voltage (Vout); and a second transistor connecting a control terminal of the first transistor to a terminal (25) supplying a positive potential (Vdd) with respect to the potential of the second terminal (22) supplying the rectified voltage, the anode of the first thyristor being connected to the common potential of voltages defined by said positive and negative potentials.