EV Converter Control for SMR-Off Leak Voltage Suppression

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Solution Overview

Problem

In electrified vehicles, when system main relays (SMRs) are disconnected, a voltage may be generated in the electric circuit including the power control unit (PCU) due to a leak current in the converter, leading to erroneous detection or learning during abnormality detection or offset learning processes.

Innovation Solution

The electrified vehicle configuration includes a converter connected to power lines between the SMRs and the drive device, with a control device that activates or stops the converter based on the voltage applied to the power lines, thereby preventing voltage generation due to leak currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the converter is connected to power lines between the relays and the drive device, then the converter can convert AC power to DC power and charge the power storage device, but a voltage may be generated in the electric circuit including the drive device due to leak current when the relays are disconnected

Engineering Contradiction:

Improvepower conversion efficiencyVSAvoidvoltage generation due to leak current

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The control device activates the converter before closing the relays to connect the power storage device and drive device. This preliminary activation ensures that the converter is ready to handle power conversion immediately when the circuit is closed, preventing voltage generation due to leak current that would occur if the converter were activated after relay closure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control device monitors the state of the relays and the voltage on the power lines, and adjusts the converter's operation accordingly. When relays are closed and power is supplied to the drive device, the control device activates the converter to prevent harmful voltage generation from leak current, ensuring safe and efficient power conversion.

Inventive Principle:

Principle #23Feedback

2Measurement precision

If abnormality detection or offset learning is performed under the assumption that no voltage is generated in the electric circuit including the PCU because the SMRs are disconnected, then diagnostic accuracy is improved, but erroneous detection or learning occurs when voltage is generated due to leak current in the converter

Engineering Contradiction:

Improvedetection accuracyVSAvoiddetection reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The control device activates the converter before performing abnormality detection or offset learning operations. This ensures that no voltage is generated in the electric circuit including the PCU during these operations, allowing accurate detection and learning without erroneous results caused by leak current-induced voltage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control device monitors the operational state and adjusts the converter's activation status based on the timing of diagnostic operations. When abnormality detection or offset learning is to be performed, the control device ensures the converter is activated to prevent voltage generation, thereby maintaining both detection accuracy and reliability.

Inventive Principle:

Principle #23Feedback

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 effectively suppresses the increase in voltage on power lines due to leak currents, reducing the occurrence of erroneous detection or learning during abnormality detection or offset correction processes when SMRs are disconnected.

Implementation Method 1

a converter connected to power lines between the relays and the drive device and configured to convert alternating current power supplied from an external power supply into direct current power and charge the power storage device

Methodology Applied

Scientific EffectElectrical energy conversion (AC to DC):

Implementation Method 2

a converter connected to power lines between the relays and the drive device and configured to convert direct current power in the power storage device into alternating current power and output the alternating current power to an outlet

Methodology Applied

Scientific EffectElectrical energy conversion (DC to AC):

Data Source

PatentUS12319153B2Electrified vehicle

Publication Date: 2025.06.03 TOYOTA JIDOSHA KK

AI summary

An electrified vehicle includes: a power storage device; an electric motor configured to drive a drive wheel; a drive device configured to drive the electric motor by using electric power in the power storage device; relays configured to connect or disconnect the power storage device and the drive device; a converter connected to power lines between the relays and the drive device; and a control device configured to activate the converter or stop the converter when a voltage is applied to the power lines to which the converter is connected.