Piezo Actuator Circuit with Segmented DC-DC Converters
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Solution Overview
Problem
Existing circuit arrangements for piezo actuators face challenges in accurately setting voltage at very low voltages while being economically viable, particularly in applications like pressure regulators for CNG-driven motor vehicles, where they require precise static voltage adjustment without high dynamic performance demands.
Innovation Solution
A circuit arrangement comprising a first DC-DC converter connected to a capacitor for stabilization, and a second DC-DC converter connected to the piezo actuator, using a half-bridge step-up converter for charging and an inverting voltage converter for charging, with a simple dissipative path for discharging, allowing for efficient voltage adjustment at low voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a complex end stage with additional dissipative paths is used for piezo actuator control, then voltage adjustment precision at low voltages is improved, but device complexity and cost increase
Solution Approach 1:
The voltage control function is segmented into two independent DC-DC converter stages: a first converter stabilizes the supply voltage from the battery, while a second converter precisely controls the piezo actuator voltage. This segmentation allows each stage to be optimized for its specific function, achieving precise low-voltage control without requiring a single complex end stage.
Solution Approach 2:
A capacitor is introduced as an intermediary energy storage element between the first DC-DC converter and the second DC-DC converter. This capacitor stabilizes the intermediate voltage and provides a clean reference for the second converter, enabling precise voltage adjustment at low voltages while simplifying the overall control architecture.
2Adaptability or versatility
If additional dissipative paths are added for discharging the piezo actuator, then discharge capability is improved, but device complexity and cost increase
Solution Approach 1:
The second DC-DC converter is designed to perform multiple functions: it charges the piezo actuator during normal operation and simultaneously serves as the discharge path when voltage reduction is required. This multi-functionality eliminates the need for separate dissipative paths, reducing circuit complexity while maintaining full discharge capability.
Solution Approach 2:
The charging and discharging functions are merged into a single bidirectional DC-DC converter circuit. By combining these opposing functions into one versatile component, the patent reduces the number of required circuit elements and simplifies the overall system architecture.
3Device complexity
If a single DC-DC converter is used for both voltage stabilization and piezo control, then device complexity is reduced, but voltage adjustment precision at low voltages deteriorates
Solution Approach 1:
The voltage control task is divided into two sequential stages performed by separate DC-DC converters. The first converter handles coarse voltage stabilization from the battery, while the second converter performs fine precision adjustment for the piezo actuator. This segmentation allows each converter to be optimized for its specific voltage range and control precision requirements.
Solution Approach 2:
The capacitor serves as an intermediary that decouples the two converter stages. It provides a stable intermediate voltage reference that enables the second converter to achieve high precision control at low voltages without being directly affected by the variations and noise from the first converter.
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 enables accurate voltage setting for piezo actuators even at low voltages, reducing complexity and cost, while maintaining operational efficiency in CNG-driven motor vehicle pressure regulators.
Implementation Method 1
a first DC-DC converter (DC1) which converts an input voltage (Ubat), which can, for example, be the voltage of a vehicle battery, into a voltage at a capacitor (C), so stabilizing the input voltage (Ubat)
Implementation Method 2
a second DC-DC converter (DC2), which transforms the voltage at the capacitor (C) into a predetermined output voltage (Uaus) for the piezo actuator (PA)
Implementation Method 3
Piezo actuators change their form, for example their length, when they are subjected to an electrical voltage
Data Source
AI summary
The disclosure relates to a circuit arrangement that includes a first DC-DC converter that is connected on the output side to a capacitor. A first terminal of the capacitor is a supply voltage terminal and a second terminal of the capacitor is a reference potential terminal. The circuit arrangement also includes a second DC-DC converter, which is connected on the input side with the capacitor and on the output side to a first terminal of a piezo actuator. The second terminal of the piezo actuator is connected to the first terminal of the capacitor.