HID Ballast Voltage Multiplier and Temperature Compensation
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Solution Overview
Problem
Conventional HID lamp ballasts require a larger transformer due to the need for two secondary windings to reduce the dc link voltage to 300 V, and they lack effective temperature compensation for consistent light output under cold and warm start conditions.
Innovation Solution
A voltage multiplier circuit that triples the dc-link voltage to 600 V, eliminating the need for additional transformer windings and using lamp voltage to charge a capacitor for temperature compensation, allowing the microcontroller to generate a suitable reference power setting based on lamp temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the dc link voltage is reduced from 300V to 200V, then the transformer size is reduced, but additional transformer windings are required
Solution Approach 1:
A voltage multiplier circuit is introduced as an intermediary component between the DC-DC converter and the igniter assembly. This circuit multiplies the reduced 200V dc link voltage to the required 600V for spark gap breakdown, eliminating the need for additional transformer windings while achieving both voltage reduction and ignition requirements
Solution Approach 2:
The voltage transformation function is segmented into two separate stages: first, the DC-DC converter reduces the battery voltage to 200V; second, the voltage multiplier circuit boosts it to 600V for ignition. This segmentation allows each component to be optimized independently, reducing overall complexity
2Reliability
If a conventional current source design is used for temperature compensation, then the compensation is effective, but the circuit complexity and cost increase
Solution Approach 1:
The lamp voltage itself is used to charge the capacitor C1, creating a self-service temperature compensation mechanism. The capacitor voltage naturally tracks the lamp voltage, which varies with temperature, providing automatic compensation without requiring complex external current sources or additional sensing circuits
Solution Approach 2:
The lamp voltage serves multiple functions: it provides the operating voltage for the lamp and simultaneously charges the temperature compensation capacitor. This multi-functionality eliminates the need for separate temperature sensing circuits, reducing overall system complexity
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 solution reduces the size of the transformer by reducing the turns ratio and ensures consistent light output under varying temperature conditions by anticipating and compensating for lamp temperature changes, improving HID ballast performance in automotive applications.
Implementation Method 1
A voltage multiplier circuit triples the dc-link voltage for the igniter assembly
Implementation Method 2
using lamp voltage to charge a capacitor for temperature compensation
Implementation Method 3
The spark gap conducts when the voltage across the capacitor is equal to the breakdown voltage (about 600 V) of the spark gap
Data Source
AI summary
The present invention relates to temperature compensation of HID lamps in automobiles. The invention concerns the manner in which the temperature of the HID lamp is accounted for in order to drive the lamp is at appropriate power from hot to cold conditions. In the present invention, the voltage across a capacitor in the temperature compensation circuit is sensed and used as a command signal to anticipate lamp temperature, and accordingly the reference power to the HID lamp is modulated depending on the temperature of the lamp. In the present invention, the lamp is driven with a higher power setting when the lamp is cold and with lower power setting when hot. This adaptive generation of reference power setting depending on the temperature of the lamp is implemented using the voltage across a capacitor in the temperature compensation circuit.