Electric Machine Operating State Detection Without Tachometer
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Solution Overview
Problem
Conventional methods for determining the operating state of electrical machines, such as speed and torque, require a tachometer, which increases size and manufacturing costs due to the need for direct current measurements.
Innovation Solution
A device and method that utilize the difference between induced electrical voltages across a series circuit of field and armature windings to determine the operating state, eliminating the need for a tachometer by using voltage detection and evaluation devices to assess the induced voltage's level, effective value, and phase position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tachometer is used to measure motor current and determine operating state, then measurement precision is improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The patent extracts the measurement function from a separate tachometer device and integrates it into the existing voltage detection system. By measuring voltage across the armature winding and deriving current information from voltage characteristics, the system eliminates the need for a dedicated current measuring tachometer, thereby reducing device complexity while maintaining measurement precision
Solution Approach 2:
The patent uses voltage measurement as an intermediary to indirectly obtain current information. Instead of directly measuring current with a tachometer, the system measures voltage across the armature winding and uses the relationship between voltage and current in the motor circuit to determine operating state, thus avoiding direct current measurement complexity
2Measurement precision
If a tachometer is used for direct current measurement, then measurement precision is improved, but manufacturing costs increase
Solution Approach 1:
The patent makes the voltage detection device multi-functional by enabling it to perform both voltage measurement and current information extraction. The same voltage detection circuit that measures armature voltage is also used to determine motor current and operating state, eliminating the need for separate expensive measurement devices and reducing overall manufacturing costs
Solution Approach 2:
The system uses its existing voltage measurement capability to serve the additional function of current measurement. By analyzing the voltage characteristics already being measured across the armature winding, the system derives current information without requiring external measurement devices, thus reducing manufacturing costs
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 precise determination of motor current and torque without a tachometer, reducing size and production costs while maintaining accuracy, by leveraging the relationship between induced voltage and measurement voltages to calculate rotational speed and current intensity.
Implementation Method 1
an armature winding in which a second electrical voltage is induced during operation of the electrical machine due to a relative movement between the fixed and movable parts of the electrical machine
Data Source
Figure 1
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AI summary
The invention relates to a device (12) comprising an electric machine (16), a voltage detection device, and an analysis device. A fixed or movable part of the electric machine (16) has a field winding (F1) to which a first electric voltage (U1) is applied. The other of the two parts of the electric machine (16) has an armature winding (24) in which a second electric voltage (Uq) is induced due to a relative movement between the fixed and the movable part of the electric machine (16). The voltage detection device is provided to detect a characteristic of the first electric voltage (U1). The analysis device is provided to detect an operating state (n, Mi, I) of the electric machine (16) in consideration of the characteristic of the first electric voltage (U1) detected. A method for determining an operating state (n, Mi, I) of an electric machine (16) comprises the following steps: directly or indirectly detecting an effective value of a first electric voltage (U1) at the field winding (F1) of the electric machine (16) and; detecting an operating state (n, Mi, I) of the electric machine (16) in consideration of the effective value of the first electric voltage (U1) detected.