Single-Sensor Motor Drive Control for Stable DC Bus Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motor drive systems require multiple current sensing locations, which increase complexity and can lead to instability in current and DC bus voltage control due to negative spikes during motor phase changes.
Innovation Solution
A single current sensor system with a signal conditioner and feedback signal processor that blanks current data for a time period after motor phase changes to stabilize the current control loop, using a single sense resistor and digital conversion for motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple current sensing locations are used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple current sensing functions into a single current sensor that measures the DC bus current. By measuring the total current flowing through the DC bus and using control algorithms to derive phase current information, the system eliminates the need for multiple separate current sensors while maintaining measurement precision for motor control purposes.
Solution Approach 2:
The single current sensor serves multiple functions: it measures the DC bus current for power management, provides information for deriving phase currents through control algorithms, and enables protection functions. This multi-functional approach reduces device complexity while maintaining measurement precision through computational methods.
2Measurement precision
If multiple current sensing locations are used, then measurement precision is improved, but control stability deteriorates
Solution Approach 1:
The patent merges multiple sensing points into a single DC bus current measurement location, eliminating the instability issues that arise from coordinating multiple sensing locations. The single measurement point provides a stable reference that simplifies the control algorithm and improves current control stability during motor phase changes.
Solution Approach 2:
The system uses feedback control algorithms that process the single DC bus current measurement to regulate motor phase currents. The feedback mechanism compensates for the limitations of single-point sensing by continuously adjusting control signals based on measured current and motor state, thereby maintaining control stability.
3Device complexity
If a single current sensor is used, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent replaces physical multiple current sensors with a computational approach. Instead of using multiple hardware sensing elements, the system uses a single physical sensor combined with mathematical algorithms and control theory to calculate and control phase currents, thereby reducing hardware complexity while maintaining measurement precision through software-based methods.
4Device complexity
If a single current sensor is used, then device complexity is reduced, but control stability deteriorates
Solution Approach 1:
The system implements feedback control that uses the single current sensor measurement to regulate DC bus voltage and motor phase currents. The feedback loop continuously monitors the DC bus current and adjusts switching signals to maintain voltage stability, compensating for the reduced sensing information through intelligent control algorithms that account for motor phase changes.
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
Stabilizes the DC bus voltage and current control, reducing complexity and maintaining accurate current readings, thereby improving motor drive performance.
Implementation Method 1
The single sensor can sense a voltage across and thereby a current passing through the sense resistor
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A motor drive system (100) includes a direct current (DC) power source and an inverter (106) comprising a plurality of switching elements (142, 144). The inverter (106) is configured to receive a DC input from the DC power source and output an alternating current (AC) to three phases of a motor (102). The system (100) also includes a single current sensor (108) arranged to sense a current from the DC power source to the inverter (106) and a control unit (104) that controls the operation of the switching elements (142, 144) based in part on an output of the single current sensor (108). A control unit (104) controls the operation of the switching elements (142, 144) based in part on an output of the single current sensor (108). The control unit (104) is configured to determine that a Hall sensor (HA, HB, HC) change has occurred and to control the operation of the switching elements (142, 144) based on a prior sensor reading for a time period (tblanking) after the Hall sensor (HA, HB, HC) change.