Thyristor Dimming Circuit Lossless Discharging Control
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Solution Overview
Problem
Conventional thyristor dimming circuits suffer from high power losses and complex structures, leading to increased power consumption and product costs due to the continuous connection of discharging circuits between bus voltage and ground.
Innovation Solution
A thyristor dimming circuit with a lossless discharging circuit that controls the main switch with a fixed duty cycle at a fixed frequency during predetermined time intervals, eliminating the need for an extra discharge switch and reducing power consumption by utilizing the existing power stage circuit to generate a phase-loss input voltage and drive a lamp load through electrical conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional active discharging circuit is used with resistor, capacitor, diode and switch, then the thyristor circuit can operate normally, but the circuit structure becomes complex with high product costs and power losses
Solution Approach 1:
The patent combines the discharging circuit functionality with the existing power stage circuit by controlling the main switch to operate in a specific mode during predetermined time intervals. This merging eliminates the need for separate discharge switches and additional components, reducing circuit complexity while maintaining reliable thyristor operation through the integrated power stage circuit.
2Device complexity
If a simple discharging circuit with resistor and capacitor series connected between bus voltage and ground is used, then the circuit structure is simple with few components, but power losses are high due to continuous connection
Solution Approach 1:
The patent implements periodic action by controlling the main switch to operate with fixed duty cycle at fixed frequency only during predetermined time intervals. This periodic operation allows the discharging circuit to be active only when needed for thyristor operation, rather than continuously, thereby significantly reducing power losses while maintaining the simple circuit structure.
3Reliability
If the discharging circuit is always connected between bus voltage and ground, then the thyristor can be discharged properly, but power consumption increases due to continuous operation
Solution Approach 1:
The patent applies dynamics by transitioning the main switch from normal power conversion operation to a specific discharging mode during predetermined time intervals. This dynamic control allows the circuit to adapt its operation based on timing requirements, enabling proper thyristor discharge only when necessary while minimizing power consumption during other periods.
4Adaptability or versatility
If the main switch is controlled with variable duty cycle and frequency, then the lamp load can be dimmed, but the circuit operation becomes complex during discharge intervals
Solution Approach 1:
The patent segments the operating intervals into distinct phases: normal power conversion intervals with variable duty cycle for dimming control, and predetermined discharge intervals with fixed duty cycle for thyristor operation. This segmentation simplifies control by applying different control strategies to different time periods, reducing overall operational complexity while maintaining lamp dimming 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
The solution provides a simplified circuit structure with reduced power consumption and minimized switching frequency, ensuring stable operation of the thyristor and preventing LED flashing or flickering, while maintaining a current charging loop for successful thyristor operation.
Implementation Method 1
a thyristor and a rectifier bridge configured to receive a sinusoidal AC voltage, and to generate a phase-loss input voltage
Implementation Method 2
a power stage circuit configured to have the phase-loss input voltage applied thereto, the power stage circuit having a main switch and being configured to drive a lamp load through electrical conversion
Data Source
AI summary
Thyristor dimming circuits and methods are disclosed herein. In one embodiment, a thyristor dimming circuit can include: (i) a thyristor and a rectifier bridge configured to receive a sinusoidal AC voltage, and to generate a phase-loss input voltage; (ii) a power stage circuit configured to have the phase-loss input voltage applied thereto, the power stage circuit having a main switch and being configured to drive a lamp load through electrical conversion; and (iii) a discharging circuit configured, during a first predetermined time interval, to control the main switch to operate with a fixed duty cycle at a fixed frequency, where the first predetermined time interval begins prior to an absolute value of the sinusoidal AC voltage being reduced to zero, the first predetermined time interval ending when the phase-loss input voltage is again applied to the power stage circuit.