Motor Controller R and L Estimation via IPD Timing
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Solution Overview
Problem
Conventional sensorless field-oriented control (FOC) algorithms for DC motor controllers require measurement of motor coil resistance (R) and inductance (L) using external instruments, leading to delays and increased costs, and rely on contact sensors that wear out over time.
Innovation Solution
A motor controller system that determines R and L values based on timing parameters obtained during an initial position detection interval by measuring current rise and fall times using a sense circuit with a comparator and clock circuitry, eliminating the need for external instrumentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external instruments are used to measure motor coil resistance and inductance values, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the measurement function from external instruments and implements it within the motor controller itself. The controller measures resistance and inductance values by injecting test currents through the motor coils and measuring the resulting voltage drops and current characteristics internally, eliminating the need for separate external measurement devices.
Solution Approach 2:
The motor controller is designed to perform multiple functions: it not only controls the motor operation but also measures the motor's electrical parameters (resistance and inductance) internally. This multi-functionality integrates what were previously separate tasks into a single device, reducing overall system complexity.
2Measurement precision
If external instruments are used to measure motor parameters, then measurement precision is improved, but productivity decreases due to delays
Solution Approach 1:
The motor controller performs parameter measurements during the initial position detection interval, before normal motor operation begins. By conducting measurements in advance during this dedicated time window, the system obtains accurate electrical parameters without delaying the start of motor operation or requiring separate measurement steps.
Solution Approach 2:
The patent combines the parameter measurement process with the initial position detection process. Both functions are performed simultaneously during the same time interval using the same hardware resources, eliminating the need for separate measurement and position detection steps that would otherwise occur sequentially.
3Reliability
If contact sensors are used to determine rotor position, then position detection reliability is improved, but device complexity and maintenance requirements increase
Solution Approach 1:
The patent replaces mechanical contact sensors with a sensorless field-oriented control algorithm that uses electrical measurements to infer rotor position. By measuring phase currents and using mathematical models to calculate back-EMF and rotor position, the system eliminates mechanical wear components while maintaining position detection capability.
Solution Approach 2:
The motor controller uses the motor's own electrical characteristics (current, voltage, resistance, inductance) to determine rotor position without requiring external sensors. The system serves itself by using its operational parameters to infer position information, eliminating the need for separate sensing components.
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
Enables accurate estimation of rotor position and generation of control signals without external instruments, reducing costs and delays, and improving motor controller efficiency by using internal timing logic to measure phase current rise and fall times.
Implementation Method 1
determine inductance and resistance values of the motor based on timing parameters obtained during an initial position detection (IPD) interval
Implementation Method 2
The sensorless FOC algorithm uses measured phase currents rather than contact sensors or Hall-effect sensors
Data Source
AI summary
A system includes: a motor having a stator and a rotor; and a pulse generation circuit coupled to the stator. The system also includes a motor controller coupled to the pulse generation circuit. The motor controller is configured to: determine inductance and resistance values of the motor based on timing parameters obtained during an initial position detection (IPD) interval; determine a rotor position based on the determined inductance and resistance values; and generate control signals for the pulse generation circuit based on the determined rotor position.