Controlling of variable DC bus voltage in a motor
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Solution Overview
Problem
Maintaining an elevated DC bus voltage during lower speed operation of a motor leads to inefficient operation and increased temperature, reducing the lifespan of motor components.
Innovation Solution
A controller adjusts the power factor of a boost converter to dynamically change the DC bus voltage by using flux-weakening control and power factor correction, based on AC supply voltage and load conditions, to mitigate temperature losses and component failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the DC bus voltage is maintained at an elevated level for high speed operation, then the motor can operate at high speed, but the motor operates inefficiently and temperature increases during lower speed operation
Solution Approach 1:
The patent implements dynamic adjustment of the DC bus voltage by controlling the boost converter's power factor according to motor speed requirements. During high speed operation, the voltage is elevated to enable high performance, while during lower speed operation, the voltage is reduced to optimize efficiency. This dynamic voltage adjustment resolves the contradiction by adapting the voltage level to the actual operational needs rather than maintaining a fixed elevated voltage.
2Speed
If the DC bus voltage is maintained at an elevated level, then high speed operation is enabled, but component temperature increases and lifespan is reduced
Solution Approach 1:
The system dynamically adjusts the DC bus voltage based on actual motor speed requirements through power factor control of the boost converter. By reducing the voltage during lower speed operation, the temperature of motor components is kept lower, extending component lifespan while still enabling high speed operation when needed.
3Power
If the DC bus voltage is elevated for high speed operation, then high performance is achieved, but operational efficiency decreases during lower speed operation
Solution Approach 1:
The patent employs dynamic power factor control of the boost converter to adjust the DC bus voltage according to motor speed and load conditions. During high speed operation, elevated voltage provides high power output, while during lower speed operation, reduced voltage optimizes operational efficiency. This dynamic adaptation resolves the contradiction between power capability and operational efficiency.
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
Reduces component temperatures and extends the lifespan of motor components by optimizing DC bus voltage through dynamic power factor adjustment.
Implementation Method 1
The boost converter 106 steps up the DC voltage that is provided by the rectifier 104 and received by the boost converter 106
Implementation Method 2
The inverter 110 converts the DC voltage into a three-phase AC voltage... The motor 102 receives the three-phase AC voltage for operation of the motor 102
Data Source
AI summary
A method and apparatus for controlling a variable direct current (DC) bus of a motor drive are provided. A controller receives, over a first input, first and second component voltages of a first direct current (DC) voltage of the electric drive and determines an additional boost ratio of the electric drive based on the first and second component voltages. The controller determines a boost ratio of the electric drive as a sum of a minimum boost ratio and the additional boost ratio. The boost ratio is a ratio by which the electric drive steps up a second DC voltage into the first DC voltage. The controller generates a control signal for controlling the electric drive based on the boost ratio and outputs the control signal over an output.