Inverter Module Gate Resistor Tuning to Reduce Parallel Switching Loss
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Solution Overview
Problem
Conventional motor drive apparatuses face challenges in suppressing loss and eliminating switching timing differences among parallel-connected switching elements, leading to increased switching loss and potential voltage distortion when driving motors at high frequencies.
Innovation Solution
The motor drive apparatus includes inverter modules with switching element pairs connected in parallel, where the resistance values of gate resistors are adjusted to synchronize switching timings, thereby equalizing the inductances and reducing switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If switching elements are connected in parallel to increase current capacity, then the current capacity is improved, but the switching timing differences among switching elements cause increased switching loss
Solution Approach 1:
The patent applies parameter changes by adjusting the gate resistor values for each switching element to compensate for differences in signal line inductance. By varying the resistance parameter, the patent equalizes the switching timing among parallel-connected switching elements, thereby reducing switching loss while maintaining increased current capacity
2Manufacturing precision
If signal lines are lengthened to equalize inductances among parallel-connected switching elements, then the inductance equalization is improved, but the switching time is prolonged and switching loss increases
Solution Approach 1:
Instead of changing the physical length of signal lines, the patent changes the electrical parameter (gate resistor value) to achieve inductance equalization. This allows the signal lines to remain short while still achieving equalized switching timing, thus avoiding prolonged switching time and reduced switching loss
3Reliability
If dead time is prolonged to avoid simultaneous short-circuiting of switching elements, then the reliability is improved, but the voltage distortion and motor iron loss increase
Solution Approach 1:
The patent uses gate resistor parameter adjustment to equalize switching timing among parallel-connected switching elements. This ensures that switching elements turn on and off simultaneously, preventing simultaneous short-circuiting without requiring excessive dead time, thereby reducing motor iron loss and voltage distortion while maintaining reliability
Data Source
AI summary
A motor drive apparatus which drives a motor includes inverter modules equal in number to phases of the motor. Each of the inverter modules includes a plurality of switching element pairs. Each of the switching element pairs is defined by two switching elements connected in series. In each of the inverter modules, the plurality of switching element pairs are connected in parallel, and each of resistance values of gate resistors connected to the switching elements is set for the corresponding switching element connected thereto.