Electronic Ballast Circuit with Strike Voltage Limiter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ballast circuits for lamps, such as high-intensity discharge and fluorescent lamps, face challenges in effectively limiting lamp strike voltage and current, leading to potential lamp longevity issues and inefficiencies in power consumption.
Innovation Solution
An electronic ballast circuit with a resonant circuit and a voltage limiter circuit that adjusts resonant frequency to clamp lamp voltage at a threshold, using varistors and capacitors to regulate voltage and prevent excessive strike voltage, while omitting resistors to reduce heat generation and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional ballast circuit uses resistors for current detection, then current control is achieved, but power consumption increases and heat generation occurs
Solution Approach 1:
The patent removes the resistor component traditionally used for current detection in ballast circuits. By extracting this component, the circuit eliminates the associated power consumption and heat generation while maintaining current control functionality through alternative means (voltage measurement and calculation).
Solution Approach 2:
The patent replaces the physical resistor-based current sensing mechanism with an electronic calculation approach. Current is determined by calculating I = V/Z based on measured voltage and known impedance, substituting the mechanical/electrical resistor sensing method with a computational approach that consumes less power and generates less heat.
2Ease of operation
If a ballast circuit allows high strike voltage, then lamp ignition is achieved, but lamp longevity decreases due to excessive voltage stress
Solution Approach 1:
The patent employs dynamic frequency adjustment of the resonant circuit. During lamp strike, the circuit operates at a frequency that generates sufficient voltage for ignition. Once the lamp is lit, the frequency shifts to clamp the voltage at a safe level, preventing excessive stress on the lamp while maintaining stable operation.
Solution Approach 2:
The patent changes the operating parameters of the resonant circuit based on lamp state. By adjusting the resonant frequency parameter, the circuit transitions between two operational modes: high-voltage strike mode and voltage-clamped run mode. This parameter change enables both effective lamp ignition and protection against voltage-induced damage.
3Device complexity
If a resonant circuit operates at fixed frequency, then circuit simplicity is maintained, but voltage clamping during lamp strike cannot be achieved
Solution Approach 1:
The patent implements a dynamically adjustable resonant frequency in the circuit. The frequency is varied based on lamp operating conditions, enabling the circuit to provide voltage clamping during strike while maintaining simplicity in the overall circuit topology. The dynamic adjustment is achieved through control circuitry that modifies the resonant frequency parameter.
Solution Approach 2:
The patent uses feedback from voltage sensing to control the resonant frequency adjustment. The circuit monitors lamp voltage and uses this feedback to adjust the resonant frequency accordingly, ensuring proper voltage clamping during strike and stable operation during run. This feedback mechanism enables automatic adaptation without complex manual intervention.
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 effectively limits lamp strike voltage, enhances lamp longevity, and improves power factor correction, reducing heat and power consumption, thereby increasing efficiency and reliability.
Implementation Method 1
a resonant circuit having a first resonant frequency configured to drive a lamp, and wherein the first resonant frequency changes to a second resonant frequency when a lamp voltage exceeds a threshold voltage, whereby said lamp voltage is clamped to said threshold voltage
Implementation Method 2
The voltage limiter circuit may comprise: a first varistor, a strike voltage charge high side capacitor and a first diode connected in series between a high side of the run capacitor and a common voltage
Data Source
AI summary
An electronic ballast circuit includes a power factor correction circuit, a control and amplifier circuit, a ballast controller circuit and a ballast driver circuit. The ballast driver circuit includes a resonant circuit that connects to a lamp and a strike voltage limiter circuit that regulates the behavior of the resonant circuit. An overcurrent sensor circuit may be included to indirectly the control the ballast controller circuit via the control and amplifier circuit. The strike voltage limiter circuit uses varistors to change the resonant frequency of the resonant circuit to limit the voltage to the lamp.