Rectangular Wave Control for Salient-Pole Generator-Motor Torque
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Solution Overview
Problem
Existing vehicular generator-motor control systems experience discontinuous current and torque due to mode changes, leading to reduced torque capability, electromagnetic noise, and inefficient voltage utilization, especially when transitioning between starter and auxiliary motor modes.
Innovation Solution
A vehicular generator-motor control apparatus using a DC-AC converter to energize a salient-pole generator-motor with rectangular wave voltages, where the conduction start angles of the stator phases are shifted relative to the rotor position and continuously adjusted based on input voltage and revolution speed, enhancing torque and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PWM sinusoidal wave control is performed with mode changeover, then the generator-motor can operate in different speed/torque modes, but the current becomes discontinuous and torque capability is reduced
Solution Approach 1:
The patent applies rectangular wave voltage control instead of PWM sinusoidal wave control to maintain continuous current flow through the motor windings during mode transitions. By controlling the conduction angles of the rectangular wave voltages, the invention ensures that current does not become discontinuous at mode changeover points, thereby maintaining continuous torque output and preventing the torque reduction that occurs with PWM control.
2Extent of automation
If PWM control is performed by turning ON/OFF voltages, then switching is enabled, but a section in which no voltage is used develops and voltage utilization factor lowers
Solution Approach 1:
The patent employs periodic rectangular wave voltage control with specifically controlled conduction angles instead of PWM switching. The rectangular wave voltages are applied in a periodic manner with defined ON and OFF periods, where the conduction angle determines the duration of voltage application. This periodic rectangular wave approach eliminates the idle voltage sections inherent in PWM control, ensuring continuous and effective voltage utilization throughout the control cycle.
3Speed
If phases are continuously changed in correspondence with revolution speed by vector control, then speed control is achieved, but electromagnetic noise suddenly enlarges at mode changeover
Solution Approach 1:
The patent changes the control parameter from PWM duty cycle modulation to rectangular wave conduction angle modulation. By controlling the conduction angles of the rectangular wave voltages in correspondence with revolution speed, the invention achieves speed control while avoiding the sudden electromagnetic noise that occurs with PWM mode changeover. The rectangular wave control method provides smoother parameter transitions during mode changes, reducing electromagnetic interference.
4Device complexity
If a rotor has non-salient poles, then the structure is simpler, but a reluctance torque is not generated and phase changes are less effective
Solution Approach 1:
The patent applies rectangular wave voltage control with optimized conduction angles that are specifically tailored to exploit the magnetic characteristics of salient-pole structures. By controlling the voltage application timing and duration in different spatial regions (phases) with different conduction angles, the invention maximizes the utilization of reluctance torque generation in salient-pole motors, thereby enhancing torque capability where the physical structure allows it.
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 results in smoother torque characteristics, increased torque capability, reduced electromagnetic noise, and improved voltage utilization, allowing for maximum motor efficiency and reduced switching losses, thus enhancing the overall performance and reliability of the generator-motor system.
Implementation Method 1
a stator of the vehicular winding field type salient-pole generator-motor is energized by rectangular wave voltages... the conduction start angles of the respective phases change substantially continuously in accordance with an input voltage of the DC-AC converter and a revolution speed of the generator-motor
Data Source
AI summary
A vehicular generator-motor control apparatus wherein a winding field type salient-pole generator-motor 1 (in FIG. 1) for a vehicle is subjected to a conduction control by a DC-AC converter 2, characterized in that a stator 1A of the vehicular winding field type salient-pole generator-motor 1 is energized by rectangular wave voltages at those conduction start angles δ of respective phases of the stator 1A which are shifted a predetermined angle relative to a rotor position, and that the conduction start angles δ of the respective phases change substantially continuously in accordance with an input voltage of the DC-AC converter 2 and a revolution speed of the generator-motor 2.