Switched Reluctance Motor Control Device for High-Speed Drive
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switched reluctance motors face challenges in controlling current at high speeds due to the need for rapid phase energization switching, which results in reduced pulse output and increased drive noise, especially at high rotational speeds.
Innovation Solution
A motor control device that includes a PWM generator and a rectangular wave generator, with the PWM generator synchronizing its carrier timing with the rising of the rectangular wave signal, allowing for switching between PWM and rectangular wave drives based on rotational speed, enabling effective current control even at high speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PWM signal timing is synchronized with excitation signal rising edge, then current control precision is improved, but at high speeds the pulse output frequency becomes insufficient
Solution Approach 1:
The patent applies dynamics by making the drive method adaptive to operating conditions. The control device dynamically switches between PWM drive method (for low speeds) and rectangular wave drive method (for high speeds) based on rotational speed detection. This allows the system to optimize current control precision at low speeds while achieving sufficient pulse output frequency at high speeds, resolving the contradiction between precision and productivity.
2Speed
If phase energization switching is performed rapidly to enable high-speed rotation, then motor speed is improved, but drive noise increases and current control becomes difficult
Solution Approach 1:
The patent applies parameter changes by switching the drive method based on rotational speed parameters. At high speeds, the rectangular wave drive method is used with optimized pulse timing and width, changing the electrical parameters to reduce drive noise while maintaining high-speed operation capability. This resolves the contradiction between speed improvement and noise reduction.
3Force
If energization phase is switched frequently to control torque at high speeds, then torque control is improved, but the number of controllable pulses decreases
Solution Approach 1:
The patent applies dynamics by adaptively changing the drive method based on operational conditions. At high speeds where pulse quantity is limited, the rectangular wave drive method provides effective torque control with fewer pulses, while maintaining the ability to control torque through optimized energization timing. This resolves the contradiction between torque control capability and pulse quantity.
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 solution allows for precise current control and reduced torque ripple by switching between PWM and rectangular wave drives, effectively managing high-speed motor operations and minimizing drive noise.
Implementation Method 1
a PWM generator (15) generating a PWM signal to be outputted to a drive circuit (11)
Implementation Method 2
a rectangular wave generator (14) outputting a rectangular wave signal of 1 pulse or more to the drive circuit (11) in 1 drive period of each phase
Implementation Method 3
a drive circuit (11) that energizes windings of a switched reluctance motor (1)
Data Source
AI summary
A motor control device including a PWM generator generating a PWM generator generating a PWM signal to be outputted to a drive circuit that energizes a winding of a switched reluctance motor; a rectangular wave generator outputting a rectangular wave signal of 1 pulse or more to the drive circuit in 1 drive period of each phase based on a rotational position of the motor; and a drive signal switcher executing switching so that a PWM drive by the PWM signal is performed when a rotational speed of the motor is equal to or less than a threshold value and a rectangular wave drive by the rectangular wave signal is performed when the rotational speed of the motor is greater than the threshold value. The PWM generator synchronizes a timing to start generation of a carrier of the PWM signal with rising of the rectangular wave signal.