Power Conversion Apparatus Dynamic Rating Control for Semiconductor Temperature
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Solution Overview
Problem
Existing power conversion apparatuses for heat treatment face inefficiencies due to temperature control delays and inaccurate junction temperature estimation, leading to potential damage of semiconductor devices, especially when operating at low frequencies or experiencing rapid temperature changes.
Innovation Solution
A power conversion apparatus and method that includes a rectifier, smoothing filter, inverter, and control unit to dynamically adjust output power based on frequency, current-applying time, and operation rate, using sensors to measure temperature and cooling water flow rates to prevent junction temperature exceedance, and a control unit that calculates maximum allowable current and suspends output when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the inverter operates at low frequency, then the temperature increase of the power semiconductor device is small, but the operation is not economical
Solution Approach 1:
The patent implements dynamic rating determination that adapts the output power limits based on the actual operating frequency. The control unit calculates the operation rate and current-applying time, then determines the rating dynamically rather than using a fixed conservative rating. This allows the inverter to operate economically at low frequencies while maintaining safety at high frequencies.
Solution Approach 2:
The patent changes the operational parameters (rating, maximum output power) based on the frequency parameter. By adjusting the rating according to the actual frequency, current-applying time, and operation rate, the system optimizes the balance between temperature control and operational economy across different operating conditions.
2Reliability
If the thermostat controls temperature by suspending output only after temperature reaches the given limit, then the junction temperature does not exceed the given temperature, but rapid temperature increase cannot be addressed due to response delay
Solution Approach 1:
The patent performs preliminary action by calculating the rating and maximum output power before the temperature actually reaches the limit. The control unit determines the operation rate and current-applying time, then proactively sets the rating based on these parameters, preventing temperature exceedance before it occurs rather than reacting after the threshold is reached.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the operation rate and current-applying time, then using this information to adjust the rating. The control unit calculates the rating based on real-time operating conditions, creating a closed-loop system that responds to changing conditions and prevents temperature exceedance through continuous adjustment.
3Measurement precision
If the temperature sensor is attached to the periphery of the power semiconductor device, then the temperature can be detected, but the measured temperature value largely varies depending on the attachment position
Solution Approach 1:
The patent uses operation rate and current-applying time as intermediary parameters to determine the rating. Instead of directly measuring temperature (which has positioning sensitivity), the system uses these electrical parameters that can be measured accurately and reliably to infer the appropriate rating, avoiding the measurement precision issues of temperature sensors.
Solution Approach 2:
The patent replaces the mechanical temperature measurement approach (physical temperature sensor attachment) with an electrical parameter-based approach. By using operation rate and current-applying time measurements to determine the rating, the system substitutes the problematic thermal measurement method with more precise electrical measurements.
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 solution allows for economical and accurate control of power conversion, preventing semiconductor device damage by dynamically adjusting output power within safe temperature limits, improving operational efficiency and reducing the risk of overheating.
Implementation Method 1
a rectifier configured to convert AC power to DC power
Implementation Method 2
an inverter configured to convert the DC power received from the smoothing filter into high-frequency power by turning the DC power on and off using a switching device
Implementation Method 3
a cooling fan for cooling the radiation fins
Implementation Method 4
heat radiation fins for radiating heat generated by the semiconductor device
Data Source
AI summary
A power conversion apparatus and a power conversion method are provided. The power conversion apparatus includes a rectifier configured to convert AC power to DC power, a smoothing filter configured to control the DC power received from the rectifier to be constant, an inverter configured to convert the DC power received from the smoothing filter into high-frequency power by turning the DC power on and off using a switching device, and a control unit configured to control the rectifier and the inverter. A rating of output power from the inverter is determined in accordance with a frequency of the high-frequency power output from the inverter, a current-applying time, and an operation rate obtained by dividing the current-applying time by a sum of the current-applying time and a non-current-applying time.