Voltage Change Rate Detection Circuit for EV Power Converters
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Solution Overview
Problem
Existing power converters for EV and HV vehicles face instability due to fluctuations in the temporal change rate of AC voltage generated by switching elements, making it difficult to accurately measure and detect in real time.
Innovation Solution
A voltage change rate detection circuit that includes a series connection of a capacitor and a resistor between a measurement target node and a reference voltage node, with a switch and rectifier circuit to output a DC signal indicating the temporal change rate, allowing for accurate detection of voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage waveform is displayed on an oscilloscope to measure the temporal change rate, then the measurement can be performed, but it takes time and effort and cannot be detected in real time
Solution Approach 1:
The patent replaces the mechanical/visual measurement method (oscilloscope waveform display) with an electronic circuit-based detection system. The detection circuit directly converts voltage changes into proportional current signals through capacitor-resistor networks, eliminating the need for visual waveform analysis and enabling real-time detection without time loss.
Solution Approach 2:
The patent introduces intermediate components (capacitors and resistors) that mediate between the voltage source and measurement system. These components transform voltage changes into proportional current signals that can be directly measured, serving as intermediaries that convert one physical quantity into another more easily measurable form in real-time.
2Measurement precision
If the voltage level fluctuates greatly with time, then the voltage change rate can be detected, but it becomes difficult to accurately measure the temporal change rate
Solution Approach 1:
The patent changes the measurement parameter from direct voltage measurement to current measurement. By converting voltage changes into proportional current signals through capacitor-resistor networks, the system measures current instead of voltage, which provides a more stable and accurately measurable parameter even when voltage fluctuates greatly over time.
3Power
If switching elements are used to generate AC voltage, then high drive voltage for motors is achieved, but the temporal change rate fluctuates due to noise or load fluctuations causing motor operation instability
Solution Approach 1:
The patent implements a feedback mechanism by detecting the temporal change rate of voltage and using this information to control the switching elements. The control circuit adjusts switching timing based on detected voltage change rates, creating a closed-loop system that maintains stable motor operation despite noise or load fluctuations by continuously adapting to actual voltage conditions.
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
Enables accurate and real-time detection of the temporal change rate of the voltage, improving the stability of motor operations by converting the voltage change into a stable DC signal, reducing the need for time-consuming waveform analysis on oscilloscopes.
Implementation Method 1
a first capacitor and a first resistor that are connected in series between a measurement target node and a first reference voltage node
Implementation Method 2
a first capacitor and a first resistor that are connected in series between a measurement target node and a first reference voltage node
Implementation Method 3
a rectifier circuit that flows a current to a connection node between the first capacitor and the first resistor from the output node
Data Source
AI summary
An electronic circuit has an output node that outputs a DC signal indicating a temporal change rate of a voltage of a measurement target node, a first capacitor and a first resistor that are connected in series between the measurement target node and a first reference voltage node, a second capacitor that is connected between the output node and a second reference voltage node, a first switch that switches whether or not to short-circuit the first reference voltage node and the output node, and a rectifier circuit that flows a current to a connection node between the first capacitor and the first resistor from the output node, and cuts off a current to the output node from the connection node.