Sensorless Motor Phase Detection Before Activation
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Solution Overview
Problem
In sensorless electric motor control, the time required for phase detection significantly prolongs the period from activation signal receipt to reaching the target number of rotations, hindering quick vehicle acceleration.
Innovation Solution
An electric motor control device that performs initial phase alignment and holding current output before receiving the activation signal, and adjusts the holding current based on intake air flow to maintain rotor position, allowing for phase detection and alignment before motor activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If phase detection is performed after activation signal is received, then the electric motor can be activated in a sensorless state, but the time period from activation signal receipt to reaching target number of rotations becomes longer
Solution Approach 1:
The patent performs phase detection and initial phase alignment before the activation signal is received. The phase detection unit detects the rotor phase position in advance, and the initial phase alignment unit aligns the magnetic pole with a predetermined position before activation. This preliminary action eliminates the time delay that would otherwise occur after activation signal receipt, directly resolving the contradiction between sensorless activation and response time.
2Loss of time
If initial phase alignment is performed before activation signal, then the time to reach target rotations is shortened, but additional control complexity is required
Solution Approach 1:
The patent integrates the phase detection unit and initial phase alignment unit into the existing controller that also performs activation control. The controller universally handles both the preliminary phase alignment function and the subsequent activation control function, avoiding the need for separate dedicated hardware components. This multi-functionality approach shortens response time while minimizing the increase in device complexity.
Solution Approach 2:
The phase detection unit uses the motor's own electrical characteristics and back-EMF signals to detect rotor position, and the initial phase alignment unit uses the motor's electromagnetic properties to align the magnetic pole. The system serves itself using its inherent characteristics rather than requiring external sensors or complex auxiliary systems, reducing overall device complexity while achieving faster response.
3Loss of time
If holding current is output to maintain rotor position, then phase detection can be completed before activation, but energy is consumed during the period before activation
Solution Approach 1:
The patent outputs holding current only during the specific period from when the phase detection unit completes phase detection to when the activation signal is received. This periodic or time-limited action allows phase detection to be completed before activation with minimal energy consumption, as the holding current is not continuously supplied but only when necessary for maintaining rotor position during the pre-activation phase detection period.
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 approach reduces the time from activation signal receipt to reaching the target number of rotations, enabling faster vehicle acceleration by eliminating unnecessary phase detection time.
Implementation Method 1
an inverter that supplies power to the electric motor
Implementation Method 2
a phase holding unit of the controller causes a holding current to be output to the inverter, the holding current holding the magnetic pole of the rotor of electric motor at the predetermined position with respect to a stator
Data Source
AI summary
A sensorless electric motor control device is provided that completes a phase detection of a rotor before an activation signal is received, so as to shorten a time period from when the activation signal is received to when the rotor reaches a target number of rotations. The control device for a sensorless electric motor 10 includes an inverter 11 that drives the electric motor 10 and a first processor 18 that serves as a phase detection unit that causes the inverter 11 to perform a phase detection before the inverter 11 receives an activation signal that activates the electric motor 10, wherein the phase detection aligns a magnetic pole of a rotor of the electric motor 10 with a predetermined position with respect to a stator.