Electric Motor Control Device Switching Modulation to Reduce Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electric motor control devices face issues with temperature rise and noise generation due to switching element losses, particularly during low rotational states, which can lead to reduced power supply and increased costs.
Innovation Solution
An electric motor control device that includes a control unit capable of switching between three-phase and two-phase modulation drives based on rotational speed and calculated switching losses, eliminating the need for a temperature sensor and minimizing noise and power losses by dynamically adjusting the carrier frequency and switching signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If three-phase modulation drive is used, then power supply capability is improved, but switching loss and temperature rise increase
Solution Approach 1:
The patent applies dynamics by switching between three-phase modulation drive and two-phase modulation drive based on motor rotational speed. At low speeds (≤ predetermined value), two-phase modulation is used to reduce switching loss and temperature rise. At higher speeds, three-phase modulation provides sufficient power supply capability. This dynamic switching strategy optimizes both power supply capability and energy loss across different operating conditions.
Solution Approach 2:
The patent changes the modulation parameter from three-phase to two-phase based on rotational speed threshold. This parameter change reduces the number of switching operations at low speeds, thereby reducing switching loss and preventing temperature rise, while maintaining adequate power supply through parameter optimization.
2Reliability
If temperature sensor is added to detect inverter temperature, then temperature monitoring is improved, but device cost increases
Solution Approach 1:
The patent applies self-service by using the control unit's existing computational resources to calculate switching loss and estimate temperature without external sensors. The control unit calculates switching loss based on modulation waveforms and compares it with threshold values to determine when temperature rise may occur, then switches to two-phase modulation preemptively. This eliminates the need for temperature sensors while maintaining reliable temperature monitoring capability.
Solution Approach 2:
The patent replaces the physical temperature sensor measurement system with a computational model that estimates temperature based on switching loss calculations. This substitution eliminates hardware complexity and cost while achieving the same monitoring objective through mathematical modeling and control algorithm.
3Object-affected harmful factors
If carrier frequency is changed to reduce noise, then electromagnetic noise is reduced, but control precision may deteriorate
Solution Approach 1:
The patent dynamically adjusts carrier frequency based on operational conditions. When switching to two-phase modulation at low speeds, the carrier frequency is optimized to reduce electromagnetic noise from switching operations. The control precision is maintained through adaptive adjustment that considers both noise reduction and control accuracy requirements, ensuring optimal performance across different speed ranges.
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
The device effectively suppresses temperature rise and noise, ensuring stable power supply and driving force generation even at low rotational speeds, without the need for a temperature sensor, thereby reducing costs and improving operational efficiency.
Implementation Method 1
a power converter (inverter) which converts the DC power from the charging device into alternating current (AC) power and supplies the power to the electric motor, and the like, in addition to the electric motor. The power converter which supplies the power to the electric motor converts the DC power into the AC power three-phase modulation drive pulse width modulation (PWM) control that uses switching elements such as insulated gate bipolar transistors (IGBTs).
Implementation Method 2
the switching element generates heat by a loss (switching loss) generated by the switching operation and the temperature of the switching element rises
Data Source
AI summary
An electric motor control device drives a power converter (30) by two-phase modulation drive based on calculation of a driving method setting and element loss calculation section (16) when an electric motor (4) is equal to or less than a predetermined rotational speed; and switches switching signals from a switching signal generation section (14) to switch a switching operation of the switching elements when a loss integrated value of a first switching element with a large switching loss or a second switching element exceeds a predetermined value.