Motor Control Device Voltage Detection via Segmented Off Periods
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-frequency PWM control of motors leads to increased vibration and operation noise, making it difficult to accurately detect the voltage between motor terminals, which is essential for determining the rotation state and controlling the motor effectively.
Innovation Solution
A motor control device with a driving controller and an off controller that performs separate on/off control periods, allowing for longer off control periods during which the voltage between terminals can be accurately measured, independent of the driving frequency, thereby reducing operation noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PWM control cycle is extended to enable voltage detection, then voltage detection accuracy is improved, but motor vibration and operation noise increase
Solution Approach 1:
The patent divides the control cycle into two independent periods: a first period for PWM on/off control and a second period (longer than the first) for motor off control and voltage detection. This segmentation allows voltage measurement during the extended off period without compromising the PWM control frequency, thereby reducing motor vibration and noise while maintaining detection accuracy.
2Object-generated harmful factors
If driving frequency is increased to reduce motor vibration, then motor smoothness is improved, but voltage detection becomes difficult
Solution Approach 1:
The system performs preliminary off control of the motor before voltage detection is needed. By initiating the off control in advance and maintaining it for a duration longer than the PWM control period, the system ensures that the motor is fully stopped and voltage has stabilized before measurement begins, enabling accurate detection even at high driving frequencies.
3Object-generated harmful factors
If PWM control frequency is increased to improve motor smoothness, then motor operation quality is improved, but processing load on A/D conversion increases
Solution Approach 1:
The system uses the motor's own off period to perform voltage detection, eliminating the need for separate detection cycles. The off control period serves dual purposes: allowing the motor to stop smoothly and providing the time window for voltage measurement, thereby reducing processing load without compromising motor operation quality.
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 detection of the voltage between motor terminals even at high driving frequencies, reducing motor and pump operation noise, and enhancing the control and reliability of the motor control system.
Implementation Method 1
The rotation state of the motor can be determined based on a counter electromotive force of the motor which is obtained by detecting a voltage between terminals of the motor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A motor control device (a motor driver 200) for controlling, by a duty control, a current supplied to a motor 9 includes a driving controller 220, an off controller 230, and a voltage acquiring section (an A/D conversion processor 210, a sampling section 240). The driving controller 220 performs on/off control of the current supplied to the motor 9 with a first period. The off controller 230 performs off control for the motor 9 with a second period separately from the on/off control performed by the driving controller 220. The second period is longer than the first period. The voltage acquiring section acquires a voltage between terminals of the motor during a time period in which the off control is performed by the off controller.