Motor Control Circuit With Power-Frequency Current Compensation
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Solution Overview
Problem
Conventional motor control circuits without large electrolytic capacitors experience unstable bus voltage and working current due to the use of small capacitance capacitors, leading to unstable motor output power and inaccurate current correction values, especially when operating with different AC power supplies.
Innovation Solution
A motor control method that involves collecting real-time current waveforms, obtaining periodic voltage waveforms, determining the power frequency, compensating the current waveform, and controlling the motor based on the target current waveform, using a rectification circuit with a target capacitor of less than a preset capacity threshold and connected in parallel with the AC power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large electrolytic capacitor is used in the rectification circuit, then the bus voltage is stable, but the circuit board volume increases
Solution Approach 1:
The patent divides the rectification circuit into two separate rectification circuits instead of using one large capacitor. Each rectification circuit uses a small capacitor, and they work in parallel to achieve the voltage stabilization function that would otherwise require a large capacitor, thereby reducing circuit board volume while maintaining bus voltage stability.
2Volume of stationary object
If a capacitor with small capacitance is used to reduce circuit volume, then the circuit board volume decreases, but the bus voltage becomes unstable
Solution Approach 1:
The patent combines two rectification circuits with small capacitors in parallel to achieve the voltage stabilization function. By merging the output of both rectification circuits, the system attains the stability that would require a single large capacitor, while maintaining reduced circuit board volume.
3Adaptability or versatility
If a correction value is introduced for current control in tools used with different AC power supplies, then the tool can adapt to different power supplies, but the correction value becomes inaccurate due to power frequency judgment requirements
Solution Approach 1:
The patent uses feedback by sampling the periodic voltage waveform signal multiple times to detect the power frequency of the AC power supply. This feedback mechanism allows the system to automatically adapt to different power frequencies without requiring manual judgment or complex correction value calculations, thereby maintaining both adaptability and precision.
Solution Approach 2:
The patent implements dynamic adaptation by continuously sampling the voltage waveform to detect power frequency changes. This dynamic approach allows the current correction to automatically adjust to different AC power supply frequencies, eliminating the need for static correction values and manual frequency judgment.
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 solution stabilizes the bus current and output power of the motor by accurately compensating for fluctuations in the power frequency, thereby improving the operating performance of tools across different AC power supplies.
Implementation Method 1
a first rectification circuit, a second rectification circuit, and a target capacitor... the first rectification circuit and the second rectification circuit are connected in parallel to two output ends of the AC power supply and configured to rectify the AC power supply
Implementation Method 2
a first rectification circuit, a second rectification circuit, and a target capacitor, a capacitance value of the target capacitor being less than a preset capacity threshold
Data Source
AI summary
A motor control method and a motor control circuit. The motor control method includes: collecting a real-time current waveform of an AC power supply through a sampling circuit; obtaining a periodic voltage waveform signal of the AC power supply through a rectification circuit; obtaining a power frequency of the AC power supply by sampling the periodic voltage waveform signal multiple times; compensating the real-time current waveform and generating a target current waveform according to the power frequency; and controlling the motor according to the target current waveform. The rectification circuit includes: a first rectification circuit, a second rectification circuit, and a target capacitor; the first rectification circuit and the second rectification circuit are connected in parallel to two output ends of the AC power supply and configured to rectify the AC power supply; a controller is connected to an output end of the second rectification circuit.