Integrated Electric Compressor Voltage Ripple Reduction

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Solution Overview

Problem

The challenge is to reduce the size of on-vehicle air conditioner compressors while minimizing voltage ripples and radio noise, as high-capacity capacitors occupy excessive space and low-capacity capacitors increase voltage ripples, and existing noise reduction components are bulky, hindering downsizing.

Innovation Solution

An integrated electric compressor design incorporating a ripple reducing circuit with a capacitor and reactor connected by a bus bar, along with a snubber circuit featuring surface-mounted components to reduce radio noise, which allows for downsizing while effectively managing voltage ripples and noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a high-capacity capacitor is used to smooth voltage supplied from the battery, then voltage ripples are reduced, but the space required in the housing increases

Engineering Contradiction:

Improvevoltage smoothing effectVSAvoidhousing space

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent combines the capacitor and reactor into a single integrated voltage smoothing circuit, where the capacitor (capacity: 470 µF to 2200 µF) and reactor (inductance: 10 µH to 100 µH) work together to reduce voltage ripples. This merging allows achieving effective voltage smoothing with smaller individual components compared to using a large capacitor alone, thereby reducing the overall housing space requirement while maintaining the voltage smoothing effect.

Inventive Principle:

Principle #5Merging (Combining)

2Volume of stationary object

If a low-capacity capacitor is used to save space, then housing size is reduced, but voltage ripples increase undesirably

Engineering Contradiction:

Improvehousing spaceVSAvoidvoltage stability

Core Design Contradiction:

Volume of stationary objectVSReliability

Solution Approach 1:

The patent introduces a reactor (inductor) as an intermediary component between the capacitor and the power source. The reactor with inductance of 10 µH to 100 µH acts as a mediator that, together with the low-capacity capacitor (470 µF to 2200 µF), forms an LC filtering circuit. This intermediary component enables effective voltage ripple reduction while allowing the use of smaller capacitor capacity, thus saving housing space without compromising voltage stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If common mode capacitors and common mode coil are provided to reduce radio noise from leakage current, then radio noise is reduced, but the part size increases

Engineering Contradiction:

Improveradio noiseVSAvoidcomponent size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of stationary object

Solution Approach 1:

The patent extracts the radio noise reduction function from the conventional common mode capacitor and common mode coil configuration and integrates it into the voltage smoothing circuit itself. By using the capacitor and reactor in the voltage smoothing circuit to also handle the leakage current path, the dedicated common mode noise reduction components are eliminated, reducing part size while maintaining radio noise reduction effectiveness.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent makes the capacitor and reactor in the voltage smoothing circuit serve multiple functions: they smooth voltage ripples from the battery and simultaneously provide a low-impedance path for leakage current to reduce radio noise. This multi-functionality eliminates the need for separate common mode noise reduction components, achieving radio noise reduction without increasing component size.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution achieves efficient motor operation with reduced voltage ripples and noise, enabling smaller compressor housings and improved assembly workability, while minimizing the size of noise-reducing components, thus addressing the need for compact on-vehicle equipment.

Implementation Method 1

a ripple reducing circuit formed by a capacitor and a reactor which are provided between a power source for applying a voltage to the motor and the control board to reduce the ripples of a voltage supplied from the power source

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

Methodology Applied

Scientific EffectInductance: Inductor

Implementation Method 3

the ripple reducing circuit is connected to the power source side and the control board by a bus bar. Also, the bus bar itself can be provided with reactance, and can function as a part of the ripple reducing circuit

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentUS8308442B2Integrated electric compressor

Publication Date: 2012.11.13 MITSUBISHI HEAVY IND LTD

AI summary

There is provided an integrated electric compressor having a circuit configuration capable of decreasing the size thereof while restraining current ripples. In an inverter of the electric compressor, by providing a capacitor 13 and a reactor 14 between a power source and an inverter board 12, the ripples of a driving voltage is restrained, and a motor can be driven with high efficiency and the size of a housing can be decreased. Further, by connecting the capacitor 13 and the reactor 14 to a power board 16 by using a bus bar 23, the voltage ripple restraining effect is further increased, and the capacitor 13 and the reactor 14 are unitized integrally by the bus bar 23 to improve the assembling workability of the power board 16.