Inverter-integrated electric compressor
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Solution Overview
Problem
Conventional inverter-integrated electric compressors face challenges in effectively suppressing common mode current noise while achieving size reduction due to long reflux loops and the need for large noise reduction components, which hinder space-saving designs.
Innovation Solution
The inverter-integrated electric compressor incorporates noise reduction elements such as snubber circuits, capacitors, normal mode coils, three-phase common mode coils, and ferrite cores within a bus bar assembly, arranged in a stacked configuration to minimize wiring length and reduce component size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an EMI filter with a common mode coil and Y capacitor is mounted on the power input unit to reflux common mode current, then noise reduction is achieved, but the wiring length from the switching element to the EMI filter expands, resulting in a large reflux loop that reduces filter effectiveness and requires a larger common mode coil
Solution Approach 1:
The invention extracts the EMI filter function from the conventional power input unit location and integrates it directly into the bus bar structure. The bus bar itself is configured to serve as the common mode coil, with the Y capacitor connected to the housing, separating the noise reduction function from traditional wiring-based EMI filters and eliminating the need for long wiring paths.
Solution Approach 2:
The invention nests the EMI filter components within the bus bar assembly. The common mode coil is formed by the bus bar's own structure, and the Y capacitor is integrated into the same assembly, creating a compact nested configuration where the noise reduction elements are contained within the wiring structure itself, minimizing reflux loop area.
2Object-affected harmful factors
If a snubber circuit is mounted on the control board to reduce noise, then radio noise is reduced, but the control board becomes large to secure sufficient creepage distance for insulation
Solution Approach 1:
The invention merges the snubber circuit with the bus bar assembly rather than mounting it separately on the control board. The capacitor and resistor elements are integrated into the same structural assembly as the EMI filter, combining multiple noise reduction functions in a single compact location and eliminating the need for additional control board space.
Solution Approach 2:
The bus bar assembly serves as an intermediary structure that hosts both the EMI filter and snubber circuit components. This intermediate structure provides the necessary insulation and creepage distance through its physical construction, eliminating the need for the control board to be enlarged for insulation purposes while still accommodating the noise reduction circuits.
3Volume of stationary object
If the inverter device is integrated in a housing to achieve downsizing, then space saving is achieved, but various parasitic couplings increase common mode current noise
Solution Approach 1:
The invention addresses parasitic couplings by providing dedicated noise reduction paths that equalize potential differences. The Y capacitor connects the bus bar to the housing, creating a controlled capacitive coupling path that manages the parasitic effects rather than allowing uncontrolled noise generation from the integral housing structure.
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 configuration allows for effective noise suppression by shortening reflux paths and reducing the need for large EMI filters, enabling miniaturization of the compressor while maintaining seismic performance and insulation.
Implementation Method 1
inserting a snubber circuit consisting of a resistor and a capacitor for reducing noise
Implementation Method 2
inserting a snubber circuit consisting of a resistor and a capacitor for reducing noise
Implementation Method 3
mounting an EMI filter constituted of a common mode coil and a Y capacitor
Implementation Method 4
a large common mode coil having sufficient impedance must be inserted
Implementation Method 5
refluxing the common mode current (noise) flowing out from the switching element to the housing via the parasitic coupling (parasitic capacitance)
Implementation Method 6
a ferrite core connected between the switching element and the motor
Implementation Method 7
a ferrite core connected between the switching element and the motor
Data Source
AI summary
There is provided an inverter-integrated electric compressor which makes it possible to effectively suppress noise caused by a common mode current while achieving a size reduction. The inverter-integrated electric compressor includes an inverter device 3 which has upper and lower arm switching elements 13 and 16 and applies a three-phase AC output to a motor M. The inverter-integrated electric compressor injuries a control board which controls the switching of the upper and lower arm switching elements13 and 16, and a bus bar assembly 22 provided to establish wiring among a battery 24, the control board, the upper and lower arm switching elements 13 to 18, and the motor M. A normal mode coil 40, a three-phase common mode coil 41, a ferrite core 42, reflux capacitors 43 and 44, and a snubber circuit 52 are arranged in the bus bar assembly 22.