Phase Control Apparatus Transformerless Gate Drive
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Solution Overview
Problem
Existing phase control apparatuses for AC loads using transistors as switching elements face challenges in generating a stable gate or base drive voltage efficiently, leading to electromagnetic noise and requiring large, costly, and heavy transformer-based gate power supplies.
Innovation Solution
A phase control apparatus that uses a simple, space-saving, and lightweight circuit configuration for full-wave rectification to generate a stable drive voltage for transistors, eliminating the need for transformers by employing a diode bridge, zener diodes, and capacitors to switch potentials between the control terminals of transistors connected in series with the AC load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a transformer-based gate power supply is used to generate gate drive voltage, then the gate drive voltage can be obtained from AC voltage, but the installation area increases, cost increases, and weight increases
Solution Approach 1:
The invention extracts and eliminates the transformer component from the gate power supply circuit. Instead of using a transformer-based isolation power supply, the patent employs a simple RC circuit with a capacitor and resistor to generate the gate drive voltage directly from the AC line voltage, thereby removing the heavy and bulky transformer while still achieving the necessary voltage transformation and isolation functions.
Solution Approach 2:
The invention changes the operating parameters of the circuit by using a capacitor-based voltage division approach instead of transformer-based voltage transformation. The capacitor C1 and resistor R1 form a voltage divider that generates the required gate drive voltage from the AC line, operating at different electrical parameters (reactive vs. resistive) to achieve the same functional outcome with reduced weight and size.
2Reliability
If full-wave rectification is performed to generate stable gate drive voltage, then the gate drive voltage stability improves, but the circuit configuration becomes more complex
Solution Approach 1:
The invention employs inexpensive, simple components (capacitor C1, resistor R1, diodes) to achieve full-wave rectification and voltage stabilization without requiring complex or expensive circuitry. The RC circuit uses readily available components that are simple in construction and easy to replace, providing stable gate drive voltage through a straightforward voltage division and rectification approach rather than complex regulation circuits.
3Object-generated harmful factors
If transistors are used as switching elements for high current phase control, then electromagnetic noise is reduced, but a high constant voltage gate drive is required which increases circuit complexity
Solution Approach 1:
The invention enables the transistor switching circuit to serve itself by generating its own gate drive voltage from the AC line voltage through the integrated RC circuit. The capacitor C1 and resistor R1 form a self-contained voltage generation system that automatically provides the necessary high constant voltage for transistor gating without requiring external power supplies or complex gate drive circuits, allowing the high-current phase control circuit to reduce electromagnetic noise while maintaining simplicity.
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 provides a stable and efficient gate drive voltage for high current transistors, reducing electromagnetic noise and enabling cost-effective, space-efficient phase control or reverse phase control of AC loads, while suppressing erratic vibrations and light flicker.
Implementation Method 1
a diode bridge that rectifies an alternating current voltage of the alternating current power supply
Implementation Method 2
a parallel circuit of a zener diode and a capacitor
Implementation Method 3
a parallel circuit of a zener diode and a capacitor. The parallel circuit generates a high potential relative to a potential at a negative output terminal of the diode bridge, or generates a low potential relative to a potential at a positive output terminal of the diode bridge
Data Source
AI summary
A phase control apparatus includes a first transistor whose source or emitter is connected to one end of an AC power supply and whose drain or collector is connected to one end of a load, a second transistor whose source or emitter is connected to the other end of the AC supply and whose drain or collector is connected to the other end of the load, a diode bridge that rectifies an AC voltage of the AC supply, and a parallel circuit of a zener diode and a capacitor. The parallel circuit generates a high potential relative to a bridge negative output terminal potential, or generates a low potential relative to a bridge positive output terminal potential. First and second transistor control terminal potentials are switched between the high and the bridge negative output terminal potentials, or between the low and the bridge positive output terminal potentials.