Induction Cooktop Load Control via Phase Voltage Measurement
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Solution Overview
Problem
Existing electrical load control systems face challenges in accurately determining power delivery to loads due to differences in reference potentials between microcontrollers and electronic circuits, leading to approximate and often false supply voltage measurements.
Innovation Solution
An electrical load control system that includes a measuring device to generate an output signal representative of the supply voltage, allowing the microcontroller to determine real-time supply voltage values, using a voltage rectifier and a resistive voltage divider bridge with a Zener diode and optocoupler for galvanic isolation, enabling accurate power determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different reference potentials are used for each phase to ensure electrical isolation, then electrical safety is improved, but voltage measurement accuracy deteriorates
Solution Approach 1:
The patent introduces an intermediary measurement device that includes a voltage divider bridge, Zener diode, and optocoupler. This intermediary circuit measures the supply voltage on one phase relative to another phase's reference potential, then transmits the measurement data to the microcontroller without direct electrical connection. The optocoupler acts as the intermediary that transfers measurement information while maintaining galvanic isolation, thus resolving the contradiction between electrical isolation and measurement accuracy.
2Device complexity
If theoretical voltage curves are used for voltage determination, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The measurement device performs self-measurement of the actual supply voltage using the available phase voltages and reference potentials. Instead of relying on external theoretical curves, the system uses its own measured data (derived from the voltage differences between phases and reference potentials) to determine accurate instantaneous voltage values. This self-service approach eliminates the need for complex external measurement equipment while maintaining high measurement precision.
3Reliability
If galvanic isolation means are implemented between measurement device and microcontroller, then electrical safety is improved, but device complexity increases
Solution Approach 1:
The optocoupler serves as the galvanic isolation intermediary between the measurement device and microcontroller. The measurement device measures voltages on high-potential circuits, then uses the optocoupler to transmit measurement data to the microcontroller without direct electrical connection. This intermediary approach provides necessary electrical safety isolation while keeping the isolation circuit simple and cost-effective, avoiding the need for complex isolation architectures.
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 system reliably determines the power to be delivered to electrical loads by measuring real supply voltage values, ensuring accurate operation and reducing costs by eliminating the need for galvanic isolation in certain configurations.
Implementation Method 1
galvanic isolation means disposed between said voltage divider bridge and the microcontroller and comprising an optocoupler connected between said transistor and said microcontroller
Implementation Method 2
a Zener diode connected in series with said voltage divider bridge
Implementation Method 3
supply means comprising a voltage rectifier, the at least two supply voltages formed being respectively the sinusoidal voltages of said at least two phases of the electrical distribution after rectification
Data Source
Figure 1
Figure 2~3
AI summary
An electrical load control system (30) receives at least two phases (PH1, PH2) from an electrical distribution network, each phase (PH1, PH2) constituting a supply voltage (U1(t), U2(t)) with respect to a reference potential (UREF1, UREF2), the control system (30) comprising a microcontroller (11), a reference potential (UREF2) associated with the microcontroller (11) being different from at least one of the reference potentials (UREF1) associated with the phases (PH1, PH2).The control system (30) includes a measuring device (10A) for at least one first supply voltage (U1(t)) relative to a reference potential (UREF1) different from the reference potential (UREF2) associated with the microcontroller (11). The measuring device (10A) generates an output signal (u1(t)) representative of the first supply voltage (U1(t)). The microcontroller (11) is configured to determine the value of said first supply voltage (U1(t)) at any given time as a function of the output signal (u1(t)). Implementation in an induction cooktop.