Inverter Gate Drive Backup Circuit for Power Loss Availability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power conversion devices lack adequate measures to handle power losses in the gate drive power supply, leading to reduced availability and potential motor control issues during voltage drops.
Innovation Solution
A power conversion device with an inverter circuit unit, upper and lower arm switching circuits, gate circuits, a gate drive power supply circuit, and a backup power supply circuit that switches to backup power when the gate drive power voltage falls below a normal range, allowing one switching circuit to be short-circuited and the other to be opened to maintain motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply path is switched by detecting a decrease in the power of the low-voltage DC power supply, then the power can be supplied from the backup power supply to the inverter control device, but it is not possible to cope with a decrease in the power supply voltage supplied from the gate drive power supply to the gate drive circuit
Solution Approach 1:
The power supply system is segmented into multiple independent power supply paths: one for the inverter control device and another for the gate drive circuit. Each path has its own backup power supply mechanism, allowing the gate drive circuit to maintain operation independently even when the gate drive power supply voltage decreases, thereby improving overall system reliability and adaptability to power loss conditions
2Productivity
If one switching circuit is caused to be in a short-circuited state and the other in an opened state, then the motor can be driven during backup power supply operation, but the switching elements may be damaged under abnormal voltage conditions
Solution Approach 1:
The control device detects abnormal voltage conditions before they can cause damage to switching elements. When voltage abnormalities are detected, the control device proactively clamps the gate signals to prevent the switching elements from operating under harmful conditions, thereby cushioning against potential damage while still allowing the motor to be driven through the backup power supply path
3Object-affected harmful factors
If the gate signals are clamped when voltage abnormality is detected, then switching element damage is prevented, but the motor control availability may be reduced
Solution Approach 1:
The control device acts as an intermediary between the power supply system and the switching elements. It monitors voltage conditions and mediates by clamping gate signals only when necessary to prevent damage, while otherwise allowing full motor control operation. This selective intervention protects switching elements without unnecessarily reducing motor control availability
Data Source
AI summary
An object of the present invention is to improve availability when a power is lost. In a power conversion device 1, a gate drive power supply circuit 50 can supply a gate drive power within a predetermined normal voltage range. A backup power supply circuit 70 supplies the gate drive power to a lower arm gate circuit 40 when a voltage of the gate drive power applied from the gate drive power supply circuit 50 to the lower arm gate circuit 40 falls below a normal voltage range. When the gate drive power is supplied from the backup power supply circuit 70, the lower arm gate circuit 40 drives a lower arm switching circuit 22 in a short state in which all switching elements of the lower arm switching circuit 22 are turned on.