Half-Bridge Current Measurement Using Diode Voltage Drop
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric current measurement systems in electric power converters are costly and bulky, and there is a need for reliable current sensing without these drawbacks.
Innovation Solution
Measure the voltage drop across rectifying diodes and semiconductor devices in the half bridge, combined with temperature measurements, to calculate current values, eliminating the need for bulky current sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If costly and bulky current sensors are used to measure current in electric power converters, then measurement reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces physical current sensors with an electrical measurement system that uses voltage drop measurements across semiconductor devices and diodes. By measuring voltage drops and using temperature compensation, the system calculates current values through electronic processing rather than mechanical/sensor-based detection, thereby eliminating bulky current sensors while maintaining measurement reliability
Solution Approach 2:
The patent introduces voltage drop measurements as an intermediary parameter to indirectly determine current. Instead of measuring current directly with sensors, the system measures voltage drops across known resistance elements (semiconductor devices and diodes) and uses these voltage measurements as intermediaries to calculate the actual current values through electronic processing
2Device complexity
If voltage drop measurement across semiconductor devices is used to calculate current, then device complexity is reduced, but measurement precision may be affected by temperature variations
Solution Approach 1:
The patent implements temperature compensation by measuring the temperature of semiconductor devices and diodes, then using this temperature information to correct the voltage drop measurements. The system feeds back temperature data to adjust the current calculation, compensating for temperature-induced variations in semiconductor characteristics and maintaining measurement precision across different operating conditions
Solution Approach 2:
The patent changes the measurement parameters from direct current measurement to voltage drop measurement combined with temperature measurement. By measuring multiple parameters (voltage drop and temperature) and using their relationship to calculate current, the system achieves accurate current measurement while reducing device complexity. The temperature parameter is specifically used to compensate for variations in semiconductor voltage-drop characteristics
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
Enables accurate current measurement without costly sensors, detects sensor failures, and protects converters from overvoltage and overheating, while reducing system size and cost.
Implementation Method 1
measuring a voltage drop across the rectifying diode of the other current valve when the diode is conducting and when the gate drive part is controlling the semiconductor device of the current valve to be off
Implementation Method 2
a temperature sensor arranged on a plate or board on which the current valves are mounted, or even better by a temperature sensor incorporated in the semiconductor device and diode module
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
An arrangement for measuring an electric current in an electric power converter, which circuit comprises a half bridge (11) with two current valves (12, 13) connected in series and each comprising a rectifying diode (17, 18) and at least a first of the valves has a semiconductor device (15, 16) of turn-off type connected in anti-parallel therewith. A midpoint (14) of the half bridge between the two current valves is connected to a first of opposite sides of the half bridge and opposite ends of the series connection of the valves are connected to a second of said opposite sides of the half bridge. A gate drive unit (21) controls the semiconductor devices (15, 16). The arrangement has at least a member (22, 23) configured to measure the voltage drop across the rectifying diode (17, 18) of one of the current valves or the semiconductor device (15, 16) of one of the current valves. A member (25) measures the temperature in the vicinity of the current valve for which a voltage drop is measured and a calculating unit (24) uses information about voltage drop and temperature to calculate and deliver a value of the current flowing through the current valve. 25