Sensorless Motor Drive Control for Phase Determination
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Solution Overview
Problem
Existing motor drive control devices face difficulties in properly starting up three-phase DC motors under a wide range of temperature and power supply voltage conditions, leading to issues with determining the correct conduction start phase and maintaining motor rotation.
Innovation Solution
A motor drive control device incorporating a voltage detector, A/D conversion section, initial acceleration controller, output drive controllers, and current detector, which includes power transistors and an output pre-driver to manage PWM drive signals, ensuring initial acceleration and phase determination even under varying conditions by clamping PWM duty values and adjusting drive currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Hall element is used to detect rotor position, then conduction start phase can be determined, but motor size increases
Solution Approach 1:
The patent extracts the position detection function from a physical Hall element and implements it through sensorless detection using voltage signals already present in the motor drive circuit. By taking out the requirement for a physical sensor and replacing it with electronic detection methods, the motor size is reduced while maintaining the ability to determine conduction start phase accurately
Solution Approach 2:
The patent replaces the mechanical/electrical Hall element sensor system with an electronic signal processing system. Instead of using a physical sensor to detect rotor position, the system uses voltage detection and signal processing to infer position information, substituting a mechanical sensing approach with an electronic computation approach
2Volume of moving object
If sensorless DC motor is used to reduce motor size, then motor size decreases, but conduction start phase determination becomes difficult leading to reverse rotation
Solution Approach 1:
The patent applies preliminary action by detecting voltage signals during the startup phase before full operation begins. The system performs initial position detection and conduction start phase determination during a dedicated startup sequence, ensuring accurate phase identification before the motor enters normal operation, thereby preventing reverse rotation
Solution Approach 2:
The patent implements feedback by continuously monitoring voltage signals during startup and using this information to adjust and determine the correct conduction start phase. The system uses detected voltage polarities and signal characteristics to feedback control the switching sequence, ensuring accurate phase determination without physical sensors
3Measurement precision
If PWM drive control is used for motor operation, then motor control precision improves, but startup reliability deteriorates under wide temperature and voltage ranges
Solution Approach 1:
The patent applies dynamics by implementing different control strategies for different operating phases. During startup, the system uses a specialized detection and control mode that adapts to varying temperature and voltage conditions. Once startup is successful, the system transitions to standard PWM control for normal operation, allowing each phase to use the most appropriate control method for its requirements
4Device complexity
If conventional motor startup control is used, then simple control logic is maintained, but startup fails under wide range of temperature and power supply voltage
Solution Approach 1:
The patent applies parameter changes by detecting and adapting to variations in operating conditions such as temperature and power supply voltage. The system modifies its detection thresholds, timing parameters, and control signals based on the actual operating environment, allowing reliable startup across a wide range of conditions without requiring overly complex control logic
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 reliable startup and operation of three-phase DC motors across a wide range of temperatures and power supply voltages by accurately determining conduction phases and maintaining motor acceleration.
Implementation Method 1
detects an induced voltage developed in a non-conducting phase stator coil when current flows to conducting phase stator coils
Data Source
AI summary
Motor Drive Control Device configured to properly start up various types of motors under operating conditions where motor operations are performed in a wide range of temperature and power supply voltage, includes output drive controllers that supply PWM drive output signals to an output pre-driver in such a manner as to minimize the error between a current instruction signal and a current detection digital signal. In response to a detected induced voltage generated from a voltage detector upon startup of a motor, an initial acceleration controller supplies initial acceleration output signals specifying a conducting phase for initial acceleration of the motor to the output drive controllers. The initial acceleration controller, the output drive controllers, and an output driver make a conducting phase change and perform a PWM drive to provide the initial acceleration of the motor.