Switch Drive Motor Voltage PWM With DC Link Tolerance Tracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power converters for electric motors in switch drives of electrical switches face challenges in generating motor voltage efficiently from diverse and changing supply voltages, requiring frequent recalculations of the duty cycle which consume high computing power and time.
Innovation Solution
A method and power converter system that calculates and updates the duty cycle of pulse width modulation only when there is a significant change in the DC link voltage, using a tolerance range to determine when to recalculate, thereby saving computing power and time, and includes features to monitor and display the number of calculations for stability analysis and warning generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the duty cycle is recalculated continuously to adapt to changing supply voltages, then the adaptability of the power converter is improved, but the computing power consumption and processing time increase
Solution Approach 1:
The system dynamically adjusts the recalculation frequency of the duty cycle based on the rate of change of the DC link voltage. When voltage changes are significant, recalculation occurs more frequently; when changes are minor, recalculation is reduced or skipped. This dynamic adaptation resolves the contradiction by making the computing power consumption proportional to the actual need for adaptability.
Solution Approach 2:
The invention changes the parameter of recalculation frequency from a fixed continuous value to a variable value that depends on the magnitude of voltage change. By monitoring the DC link voltage and comparing it with threshold values, the system adjusts when to recalculate the duty cycle, thereby reducing unnecessary computations while maintaining adequate adaptability to supply voltage variations.
2Manufacturing precision
If the duty cycle is recalculated frequently to maintain accurate motor voltage generation, then the precision of motor voltage control is improved, but the processing time increases
Solution Approach 1:
The recalculation timing is made dynamic rather than fixed. The system monitors voltage changes and triggers recalculation only when necessary, based on whether the change exceeds predefined threshold values. This dynamic approach maintains precision when needed while minimizing processing time during stable operating conditions.
Solution Approach 2:
The system skips unnecessary recalculation steps when the DC link voltage remains within acceptable tolerance ranges. By comparing voltage changes against threshold values, the system identifies and skips redundant computation cycles, thereby reducing processing time without significantly compromising the precision of motor voltage control.
3Power
If the duty cycle is recalculated only when voltage changes exceed a threshold, then the computing power consumption is reduced, but the responsiveness to voltage changes may be delayed
Solution Approach 1:
The system performs preliminary monitoring of the DC link voltage and pre-calculates threshold values for triggering recalculation. By having these thresholds predetermined and ready, the system can respond immediately when voltage changes exceed the thresholds, eliminating any delay in detecting significant voltage changes while still avoiding unnecessary recalculations for minor fluctuations.
Solution Approach 2:
The system implements feedback by continuously monitoring the DC link voltage and comparing it with threshold values. When the voltage change exceeds the threshold, the feedback mechanism triggers an immediate recalculation of the duty cycle. This feedback loop ensures that the system remains responsive to significant voltage changes while maintaining reduced computing power consumption during stable operating conditions.
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 approach allows for efficient generation of motor voltage from varying supply voltages by minimizing unnecessary recalculations of the duty cycle, saving time and computing power, while providing insights into voltage stability and potential fluctuations through monitoring and warning systems.
Implementation Method 1
A first power converter unit (13) is configured to generate a DC link voltage from a supply voltage
Implementation Method 2
a measuring unit (19) configured to measure an actual value of the DC link voltage
Implementation Method 3
a second power converter unit (15) configured to generate the motor voltage by pulse-width modulation of the DC link voltage
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method and to a power converter (3) for producing a motor voltage for an electric motor (7) of a switch drive (5) of an electrical switch (1). In the method, a DC link direct voltage is produced from a supply voltage and the motor voltage is produced by pulse-width modulation of the DC link direct voltage. A tolerance range for a change in the DC link direct voltage is specified, and an actual value of the DC link direct voltage is continually measured. After the first measurement of the actual value, the actual value is stored in a voltage variable. After each additional measurement of the actual value, it is checked whether the deviation of the actual value from the value stored in the voltage variable lies within the tolerance range, and the actual value is stored in the voltage variable if the deviation of the actual value from the value stored in the voltage variable lies outside of the tolerance range. After each storing of an actual value in the voltage variable, a duty cycle of the pulse-width modulation is calculated, said duty cycle being dependent on said actual value, and the pulse-width modulation is carried out with said duty cycle.