Drive Circuit Parasitic Resonance Suppression

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Solution Overview

Problem

Conventional drive circuits for parallel-connected arm switches are prone to parasitic resonance due to capacitances and inductances, leading to potential overvoltage and damage when faults occur, such as short circuits.

Innovation Solution

A drive circuit design incorporating first and second control wirings with balance resistors and switches, along with a sensor and controller, to manage the flow of electric charges and suppress parasitic resonance by adjusting resistance values and switch states based on fault detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional drive circuits are used for parallel-connected arm switches, then the circuit structure is simple, but parasitic resonance occurs due to capacitances and inductances leading to overvoltage and potential damage

Engineering Contradiction:

Improveprotection against parasitic resonance and overvoltageVSAvoidcircuit structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The drive circuit is segmented into multiple independent control wirings (first control wiring and second control wiring) with separate balance resistors for each arm switch. This segmentation allows independent control and protection of each parallel-connected arm switch, preventing parasitic resonance from affecting the entire system while maintaining overall simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Balance resistors are introduced as intermediary elements in each control wiring to suppress parasitic resonance. These resistors act as mediators that dampen oscillations caused by capacitances and inductances, protecting the arm switches from overvoltage without requiring complex active protection circuits.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If balance resistors are added to suppress parasitic resonance, then reliability improves, but device complexity increases

Engineering Contradiction:

Improveprotection against parasitic resonanceVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Balance resistors are selectively added only to the control wirings connected to parallel-connected arm switches, rather than to all switches in the system. This local application of the resistance element provides targeted protection against parasitic resonance where it is most needed, minimizing overall component count while maintaining reliability.

Inventive Principle:

Principle #3Local quality

3Ease of operation

If control wirings are extended to connect control electrodes, then all switches can be controlled, but parasitic resonance occurs due to increased inductance

Engineering Contradiction:

Improvecontrol capabilityVSAvoidparasitic resonance

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The drive circuit dynamically responds to parasitic resonance conditions by utilizing the balance resistors to dampen oscillations. The resistors provide a dissipative path for resonant currents, allowing the control wirings to maintain their extended configuration for full control capability while actively suppressing harmful resonance effects through the resistive damping.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11728802B2Drive circuit

Publication Date: 2023.08.15 DENSO CORP

AI summary

A drive circuit includes a plurality of first control wirings, a plurality of first balance resistors, a first common wiring, a first switch, a plurality of second control wirings, a plurality of second balance resistors, a second common wiring, a second switch, a sensor configured to detect a fault in controlled switches, and a controller configured to control opening and closing of the first switch when the sensor detects no fault, and control opening and closing of the second switch when the sensor detects the fault.