Phase-Voltage Sensing Circuit for Rotor Angle Offset Correction
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Solution Overview
Problem
Existing methods for calibrating electric machines, particularly high-performance synchronous motors, face challenges in accurately determining the angular position of the rotor due to errors between the position sensor readings and the instantaneous angular position of the magnetic poles, which affects optimal motor operation.
Innovation Solution
A measuring circuit and calibration process that utilizes a system comprising operational amplifiers to measure phase voltages of an electric machine, allowing for the correction of rotor position errors by comparing sensor-detected and magnetic field-derived angular positions, with data stored for optimal motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position sensor is installed on the rotor to detect angular position, then the rotor position can be measured, but reading errors occur between the sensor detection and the actual instantaneous angular position of the magnetic poles
Solution Approach 1:
The patent introduces an intermediary measurement method using voltage sensing circuits to detect the actual magnetic pole position independently of the position sensor. By measuring the back-EMF voltages on the motor phases and processing these signals through operational amplifiers and analog-to-digital converters, the system obtains an intermediate reference value that mediates between the position sensor readings and the actual magnetic field orientation, enabling error correction without modifying the position sensor itself
Solution Approach 2:
The patent implements a feedback mechanism where the voltage-based angular position measurement is continuously compared with the position sensor reading, and the difference (error) is fed back to correct subsequent position measurements. The microcontroller processes the voltage signals, calculates the angular position, compares it with sensor data, and applies correction values to compensate for sensor errors, creating a closed-loop feedback system that continuously improves measurement accuracy
2Measurement precision
If phase voltages are measured to determine rotor angular position, then the magnetic field position can be accurately determined, but additional measuring circuitry is required
Solution Approach 1:
The patent designs the voltage measuring circuit to serve multiple functions: it measures phase voltages for angular position determination, provides feedback for commutation control, and enables error correction for the position sensor. The same operational amplifier circuits and analog-to-digital converters used for position measurement are also utilized for motor control feedback, eliminating the need for separate dedicated measurement circuits and reducing overall system complexity
Solution Approach 2:
The patent merges the voltage measurement function with the existing motor control circuitry. The operational amplifiers, resistors, and capacitors that form the voltage sensing network are integrated into the control system's existing signal processing path, combining position measurement and motor control functions into a unified circuit architecture that reduces component count and simplifies the overall measuring system
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 solution accurately corrects rotor position errors, enabling precise angular position determination and optimal motor operation by using the measured phase voltages to compute and apply offset data for improved driving of the electric machine.
Implementation Method 1
a first operational amplifier 20 having its non-inverting input 6 connected to the non-inverting input 10 of at least one second operational amplifier 30, and its output 7 feedback connected, through a resistance R5, to the inverting input 5
Implementation Method 2
said third operational amplifier having its output 1 feedback connected, through a capacitance C1, to the inverting input 2
Implementation Method 3
the value of the angle of the magnetic field of the rotor is obtained through the measure of the phase voltages of the machine, which are in phase with the magnetic flux when the motor current is null
Data Source
AI summary
The present disclosure provides for a measuring circuit of the voltage of an electric machine which can be used in a system and process for calibrating electric machines using such circuit. In particular, the invention refers to a measuring circuit of the voltage of an electric motor and provides for measuring the phase voltages of a synchronous, reluctance electric motor of the type with permanent magnets, in addition to any other type of electric machine. The invention allows for calibrating an electric motor using such circuit to correct errors in the position of a rotor.