Phase-Offset Dual Switch Solenoid Driver for Noise Reduction
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Solution Overview
Problem
Existing control units in motor vehicles, such as ASICs, used to supply solenoids with defined currents, often produce audible noise due to residual alternating components in the current, which is not fully mitigated by varying switching frequencies, necessitating higher frequencies to avoid whistling sounds.
Innovation Solution
Incorporating a second switch and freewheeling unit connected in parallel to the consumer, activated in a phase-offset manner with respect to the first switch, effectively doubling the overall frequency and ensuring a uniform duty cycle, while using identical components and reducing noise emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a single switch and freewheeling unit are used in an ASIC to supply current to a solenoid, then the device can operate at frequencies up to 10,000 Hz, but audible noise and whistling sounds remain due to residual alternating components
Solution Approach 1:
The patent divides the single switching task into two separate switches (first switch and second switch) that operate in parallel but with phase offset. Each switch handles a portion of the energizing cycles, allowing the system to achieve higher effective frequencies while maintaining uniform current delivery to the solenoid.
Solution Approach 2:
The patent employs periodic switching with phase offset between two switches. The control unit activates the first and second switches at different phases during the energizing cycles, creating a periodic pattern that effectively doubles the operating frequency and reduces audible noise components.
2Object-generated harmful factors
If the switching frequency is increased beyond 10,000 Hz to eliminate audible noise, then noise emission is reduced, but the ASIC complexity and cost increase significantly
Solution Approach 1:
Instead of designing a completely new high-frequency ASIC, the patent segments the switching function across two standard-frequency switches within an expanded ASIC architecture. This allows achieving higher effective frequencies using conventional components and design approaches.
Solution Approach 2:
The patent combines two separate switching circuits operating in parallel with phase offset to achieve the effect of a single high-frequency switch. This merging approach allows the system to benefit from higher effective frequency without the full complexity of designing and manufacturing a new high-frequency ASIC.
3Speed
If phase offset activation of two switches is implemented, then the overall frequency is doubled and noise is reduced, but the device complexity increases due to additional components
Solution Approach 1:
The patent segments the high-frequency switching function into two lower-frequency switches operating in parallel with phase offset. This segmentation allows the system to achieve doubled effective frequency while using standard-frequency components that are easier to implement and control.
Solution Approach 2:
The control unit implements periodic activation patterns for the two switches with defined phase offsets. This periodic control strategy systematically manages the increased complexity by establishing regular, predictable switching sequences that simplify timing and control logic.
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 approach allows for cost-effective operation at twice the usual frequency, significantly reducing noise emissions and maintaining a uniform current profile, thereby eliminating audible vibrations.
Implementation Method 1
the control unit is designed for activating the first switch in order to energize the consumer with a predefinable electric current with the aid of pulse width modulation
Implementation Method 2
Due to the inductive portion of the electrical load, the current through the load increases as soon as the voltage is applied, and the current decreases again as soon as the voltage is disconnected again
Data Source
AI summary
A device for operating an electrical consumer, in particular a solenoid valve, including at least one first circuit which encompasses an activatable first switch and a first freewheeling unit connected or connectable in parallel to the consumer, and including a control unit which is designed for activating the first switch in order to energize the consumer with a predefinable electric current with the aid of pulse width modulation. It is provided that the circuit encompasses at least one second switch and one second freewheeling unit, which is connected or connectable in parallel to the consumer, and that the control unit is designed for activating the second switch in a phase-shifted manner with respect to the first switch in order to energize the consumer.