Semiconductor Relay High-Speed Switching via Pulse Transformer
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Solution Overview
Problem
Existing semiconductor relays face challenges in switching high voltages at high speeds due to limitations in current supply and switching speed of the MOSFETs, particularly when driven by a controller and light receiving circuit.
Innovation Solution
The semiconductor relay incorporates a power transforming circuit, a signal transmitting circuit, and a conduction turning-off circuit, including a DC/DC converter, a pulse transformer or photocoupler, and an analog switch, to enable high-speed switching of high voltages by isolating input and output terminals and using high-speed pulse transformers or photocouplers to drive MOSFET circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a controller and light receiving circuit are used to drive MOSFETs, then the relay achieves optical coupling insulation, but the current supply capability is insufficient and switching speed is limited
Solution Approach 1:
The patent divides the relay into two independent circuits: a primary circuit with optical coupling components (light emitting diode, light receiving element) and a secondary circuit with power transformation components (transformer, switching elements). This segmentation allows the optical coupling to provide reliable insulation while the separate power circuit handles high-speed switching independently, resolving the contradiction between reliability of insulation and switching speed.
2Loss of information
If a controller outputs driving signals to MOSFETs, then the relay achieves signal transmission, but large current cannot be supplied and high-speed switching cannot be achieved
Solution Approach 1:
The patent introduces a transformer as an intermediary between the optical signal receiving element and the power switching elements. The transformer couples the low-power control signal from the light receiving element to the high-power MOSFET gates, enabling signal transmission while providing the necessary current amplification to drive large power loads at high speeds.
3Power
If MOSFETs are driven by a controller, then the relay achieves voltage switching, but the switching time is too long
Solution Approach 1:
The patent replaces the conventional controller-based driving mechanism with an optically-driven switching mechanism. The light emitting diode converts electrical control signals to optical signals, which are then detected by the light receiving element to directly trigger the transformer and MOSFETs. This optical-mechanical substitution eliminates the limitations of electronic controllers, achieving extremely fast switching times while maintaining full voltage switching capability.
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 configuration allows for rapid switching of high voltages, with switching times as low as 1.2 μsec, by leveraging high-speed pulse transformers or photocouplers and analog switches, effectively addressing the limitations of previous semiconductor relays.
Implementation Method 1
one end of a resistor 102 is connected to the anode of a light emitting diode 101
Implementation Method 2
The light receiving circuit 110 includes a plurality of photodiodes or solar cells serially connected
Data Source
AI summary
The semiconductor relay comprises: an insulated type DC/DC power supply 10 having the input terminal and the output terminal insulated from each other; a pulse transformer 20 having the input terminal and the output terminal insulated from each other; an analog switch 30 which turns on and off the circuit in accordance with a state of an input signal; and a MOSFET circuit 40 which turns on and off a high voltage to a load 50. When a pulse signal is outputted from a pulse signal source 28, the pulse signal is outputted from the pulse transformer 20, and a state of the analog switch 30 is switched, a supply voltage is outputted from the output terminal of the analog switch 30, both the MOSFETs 42, 44 of the MOSFET circuit conduct, and a high AC voltage is applied to a load 50 from an AC power supply 52. Then, when a pulse signal is outputted from the pulse signal source 28, the pulse signal is outputted from the pulse transformer 20, the state of the analog switch 30 is switched, a ground voltage is outputted from the output terminal of the analog switch 30, both the MOSFETs 42, 44 of the MOSFET circuit are turned off, and the high AC voltage from the AC power supply 52 is not applied to the load 50.