Inverter Current Sensing Correction Without Extra Error-Cancel Circuits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power conversion devices face issues with increased circuit size due to the need for additional circuits to cancel out error voltage caused by electromagnetic induction, affecting current detection accuracy and motor control precision.
Innovation Solution
A power conversion device that calculates and corrects error voltage on the current detection circuit based on the inverter's operation state, using an error correction circuit to improve current detection accuracy without enlarging the circuit size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a circuit for generating negative-phase-sequence voltage and a circuit for adding voltage are provided to cancel out error voltage, then current detection accuracy is improved, but circuit size is increased
Solution Approach 1:
The patent replaces the hardware-based voltage cancellation circuit with a software-based correction method. The control circuit calculates the error voltage based on detection results and operation state, then corrects the current detection value through computational processing rather than physical circuit manipulation. This substitutes electronic hardware complexity with control algorithm complexity, resolving the contradiction between measurement precision and circuit size.
Solution Approach 2:
The patent introduces an intermediary calculation process that mediates between the raw detection voltage and the final current value. Instead of directly canceling error voltage through hardware, the control circuit uses the operation state as an intermediary to compute the error component and subtract it from the detection result, achieving accurate current detection without additional voltage generation or addition circuits.
2Measurement precision
If additional circuits are added to correct error voltage, then measurement precision is improved, but device complexity is increased
Solution Approach 1:
The control circuit performs multiple functions: it not only controls the inverter operation but also detects current and corrects detection errors using the same operational parameters. By utilizing the operation state (which is already necessary for inverter control) to simultaneously calculate error voltage, the patent avoids additional dedicated error correction circuits, reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
The system uses its own operational state information to self-correct detection errors. The control circuit leverages data already present in the control process (operation state) to calculate and compensate for detection inaccuracies, making the system self-sufficient without requiring external correction circuits or additional measurement devices.
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
Accurately detects current without increasing the circuit size, enhancing motor control accuracy and reducing the load on the control circuit by determining if correction is necessary based on operational conditions.
Implementation Method 1
a circuit for generating negative-phase-sequence voltage of induced voltage generated due to electromagnetic induction on a transmission line of a detection circuit
Data Source
Figure 1~2(c)
Figure 3(a)~3(b)
Figure 4~5
AI summary
A power conversion device according to the present invention has one end connected to a DC voltage source and another end connected to a load, and includes: an inverter circuit which converts DC voltage from the DC voltage source to AC voltage to be outputted to the load, and includes a leg in which an upper arm and a lower arm each having a switching element, and a resistor, are connected in series, and a smoothing capacitor connected in parallel to the leg; a current detection circuit which detects voltage across the resistor, to detect current of the resistor; and a control circuit which controls the inverter circuit. The control circuit corrects the current value detected by the current detection circuit, using an operation condition of the inverter circuit, and controls the inverter circuit using the corrected current value. Thus, error occurring in the current detection circuit can be corrected.