Sensorless PMSM Vector Control for Smooth Restart Under Inertia
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Solution Overview
Problem
Permanent-magnet synchronous motors without Hall sensors face challenges in controlling rotor position and starting torque, especially with large inertia loads, leading to issues like overcurrent, jerking, noise, and potential damage due to complex algorithms and high inertia.
Innovation Solution
A method for sensorless vector control using a microcontroller unit (MCU) to manage deceleration and startup pulses, monitoring external signals, and activating lower bridge switch transistors for dynamic braking, allowing smooth transitions and preventing issues like shaking and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If pre-positioning method is used to improve starting torque for large inertia loads, then starting torque is improved, but the motor continues rotating after stop signal causing overcurrent, jerking, noise, and potential damage
Solution Approach 1:
The patent implements continuous monitoring of motor rotation state and external control signals. The control system detects whether the motor is still rotating when a stop signal is received, and adjusts the startup strategy accordingly. This feedback mechanism prevents startup when rotation is detected, avoiding overcurrent and jerking issues while maintaining reliable control.
Solution Approach 2:
The patent dynamically adjusts the control strategy based on real-time motor state. When a stop signal is received, the system checks the rotation state and determines whether to allow startup based on current speed conditions. This dynamic adaptation resolves the contradiction by making the control system flexible rather than fixed, preventing harmful effects while maintaining starting torque capability when appropriate.
2Reliability
If waiting for load to stop completely before starting is implemented to avoid overcurrent and jerking, then control reliability is improved, but response time increases resulting in poor user experience
Solution Approach 1:
The patent does not require complete stopping before startup is permitted. Instead, it allows startup when rotation speed is below a threshold value, which is a partial action rather than waiting for complete stop. This reduces the waiting time and improves response speed while still preventing harmful startup conditions, thus balancing reliability and time loss.
Solution Approach 2:
The patent introduces a speed threshold parameter to determine when startup is permitted. By changing the control parameter from binary (stopped/not stopped) to continuous (speed threshold comparison), the system achieves faster response while maintaining reliability. This parameter-based control allows startup at controlled speeds rather than requiring complete stops.
3Productivity
If direct startup from pre-positioning at high speed is implemented to reduce response time, then productivity is improved, but impact voltage and large current impact occur causing shaking, jerking, noise, and potential damage
Solution Approach 1:
The patent applies preliminary anti-action by detecting high-speed rotation conditions before startup is attempted. When rotation exceeds the threshold, the system prevents startup command execution, thereby preemptively avoiding impact voltage and current impact. This preliminary protection mechanism maintains productivity by allowing quick response when safe, while preventing harmful effects when high speed is detected.
4Reliability
If Hall sensors are used to ensure stable and reliable control, then control reliability is improved, but device size and cost increase, and wiring interference reduces performance
Solution Approach 1:
The patent extracts and removes the Hall sensors from the motor system, replacing sensor-based control with sensorless vector control. This extraction eliminates the physical components (sensors, wiring) that increase complexity while maintaining control reliability through alternative control algorithms that estimate rotor position and speed without direct sensing.
Solution Approach 2:
The patent replaces the mechanical/sensor-based detection system with an electronic control-based estimation system. Instead of physical Hall sensors detecting position, the system uses electrical measurements and control algorithms to estimate rotor state. This substitution reduces physical complexity while maintaining or improving control reliability through software-based solutions.
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 prompt and smooth response to high-inertia loads, preventing shaking, jerking, and noise during start-stop cycles, while protecting hardware and improving user experience.
Implementation Method 1
inverter, instead of directly blocking a PWM pulse to the inverter
Implementation Method 2
activating lower bridge switch transistors for dynamic braking
Implementation Method 3
permanent-magnet synchronous motor
Data Source
AI summary
A method for controlling operation of a permanent-magnet synchronous motor includes: during operation of the permanent-magnet synchronous motor, receiving, by the permanent-magnet synchronous motor, a shutdown signal from an external device; uninterruptedly outputting, by a microcontroller unit (MCU), a deceleration pulse to an inverter, instead of directly blocking a PWM pulse to the inverter, and constantly monitoring a control signal sent by the external device; during a deceleration process, when the MCU receives a new startup signal and a real-time speed Vi of the permanent-magnet synchronous motor is greater than or equal to a reference speed Vref, controlling the permanent-magnet synchronous motor to rotate at a parameter approaching to a target torque T or a target speed V corresponding to the new startup signal; and blocking, by the MCU, the PWM pulse when the real-time speed Vi of the permanent-magnet synchronous motor is lower than the reference speed Vref.