Resistor Switching Assembly with Intermediate Potential Control
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Solution Overview
Problem
Conventional methods for reducing electromagnetic interference (EMI) caused by switching and pulse width modulation of heat-emitting resistors, such as those used in electrical heating applications, often require costly shielding, bulky filter components, or slowing of switching frequencies, which are not always feasible or desirable.
Innovation Solution
A control device with two switching devices connected in series to maintain the resistor at an intermediate potential between on and off states, synchronously switching to minimize current flow through ground connections and reduce EMI, potentially using high-resistance resistors and capacitors for compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield is used to reduce EMI, then electromagnetic interference is reduced, but device complexity and cost increase
Solution Approach 1:
The patent introduces a compensation apparatus with a second resistor and capacitor connected in parallel to the first resistor. This compensation apparatus acts as an intermediary that generates opposite polarity currents to cancel out the EMI currents, thereby reducing electromagnetic interference without requiring a physical shield.
Solution Approach 2:
The patent converts the harmful EMI currents generated by the resistor into a beneficial effect by using the compensation apparatus to generate equal and opposite currents. The harmful capacitor currents are transformed into useful compensating currents that cancel out the interference, turning the problem into a solution.
2Object-affected harmful factors
If filter components are used to reduce EMI, then electromagnetic interference is reduced, but device complexity, weight and volume increase
Solution Approach 1:
The compensation apparatus serves as an intermediary that actively compensates for EMI without requiring bulky filter components. The second resistor and capacitor work together to generate compensating currents that cancel out interference, providing a more compact solution than traditional filters.
Solution Approach 2:
The compensation apparatus is self-regulating and automatically adjusts the compensating currents based on the EMI generated by the resistor. The system serves itself by using the resistor's own switching actions to generate the compensating signals, eliminating the need for external filter components.
3Object-affected harmful factors
If switching frequency is slowed to reduce EMI, then electromagnetic interference is reduced, but productivity decreases
Solution Approach 1:
The patent converts the harmful high-frequency EMI into a beneficial effect by using the compensation apparatus to generate opposite polarity currents that cancel out the interference. This allows high-frequency switching to continue without EMI problems, maintaining productivity while reducing interference.
Solution Approach 2:
The compensation apparatus acts as an intermediary that processes the EMI signals and generates compensating currents. This allows the system to maintain high switching frequencies while the compensation apparatus handles the EMI cancellation, separating the productivity function from the interference reduction function.
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 effectively minimizes EMI by ensuring that currents generated by capacitance between the resistor and housing are compensated, reducing the need for additional shielding or filter components and maintaining efficient switching operations.
Implementation Method 1
The capacitors C1 to C5 correspond to a symbolic depiction of a capacitance that is associated with the resistor and is caused by the spatially close connection of the resistor to the housing
Implementation Method 2
a heat-emitting first resistor
Data Source
AI summary
An assembly, comprising a heat-dissipating first resistor, control device for controlling the first resistor, as well as a grounded component, which lies on a potential without direct relation to a control voltage.The first resistor is arranged in spatial vicinity of the grounded component and comprising a first and a second connection.The control device comprises a first switching device and a second switching device.The first switching device, first resistor and second switching device form a series connection.A compensation device is configured such that in the On-state of the first resistor a voltage is applied between the first and second connection, wherein the resistor in the off-state is held on an in-between potential that lies between the first and the second potential and/orthe control device is configured to trigger the first resistor in a pulse width modulated fashion, such that the first as well as the second switching device are switched synchronously.