Load Current RMS Control Using Duty-Cycle Sampling
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Solution Overview
Problem
Existing controller devices for managing the effective value of an electric load current at a time-variant load require a large number of electronic components, leading to increased manufacturing effort and costs.
Innovation Solution
A controller device that acquires a sample value of the electric load current during at least one pulse phase of a voltage pulse sequence and determines the actual effective value using a stored dependency, such as a characteristic-value table or mathematical function, allowing for the adaptation of the duty cycle to control the load current effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-frequency sampling of the load-current curve is performed with program-based summation and averaging in a control unit, then the actual effective value of the load current can be determined, but the controller device requires sufficient processor power and complex electronic components
Solution Approach 1:
The patent extracts the complex processing functions (summation and averaging of current-curve samples) from the control unit and relocates them to a dedicated measurement shunt. This separation allows the control unit to perform only simple measurements while the shunt handles the computationally intensive calculations, thereby reducing the processor power requirements and electronic component complexity in the main controller device while maintaining the ability to determine the actual effective value of the load current
Solution Approach 2:
The patent introduces a measurement shunt as an intermediary component between the load current source and the control unit. This shunt acts as a mediator that performs the complex summation and averaging operations on the current-curve samples, converting the raw current data into the actual effective value. This intermediary handles the computational burden, allowing the main control unit to remain simple while still achieving precise current measurement
2Measurement precision
If an integrator is used to perform summation and averaging of the current-curve, then the actual effective value of the load current can be determined, but the controller device requires additional electronic components
Solution Approach 1:
The patent replaces the traditional analog integrator (a mechanical/electronic component-based system) with a digital processing approach implemented in the measurement shunt. Instead of using physical integrator circuits to perform summation and averaging, the system uses digital algorithms programmed in the shunt to achieve the same mathematical operations. This substitution eliminates the need for additional analog electronic components while maintaining the measurement precision required for determining the actual effective value of the load current
Data Source
AI summary
A controller device for controlling an effective value of an electric load current at a time-variant load is provided. The controller device provides at the time-variant load a voltage pulse sequence having a duty cycle in at least one pulse phase of the voltage pulse sequence. A sample value of the electric load current is acquired at the time-variant load, to determine an actual effective value of the electric load current using a dependency stored in the controller device. The actual effective value is assigned to the sample value of the electric load current. A difference value between the actual effective value of the electric load current and a setpoint effective value of the electric load current is determined, and adapted duty cycle of the voltage pulse sequence is determined from the difference value, and provides at the time-variant load an adapted voltage pulse sequence having the adapted duty cycle.