Boost Converter Control for Brushless DC Motor
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Solution Overview
Problem
Existing control devices for boost converters face challenges in reducing processing load and achieving high-speed control processes for brushless DC motors due to interferences between boost control and current supply control processes.
Innovation Solution
A control device for a boost converter that sets the boost voltage command based on counter electromotive voltage and torque commands for a brushless DC motor, allowing independent timing for boost control and current supply control processes, and includes features like angular speed detection, temperature compensation, and phase control to adjust counter electromotive voltage constants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If boost control process and current supply control process are performed at independent timing, then processing load is reduced and control speed is improved, but it becomes difficult to coordinate the control processes
Solution Approach 1:
The control device segments the control processes into distinct functional modules: a boost control module that operates independently to generate boost voltage commands, and a current supply control module that handles motor current control. This segmentation allows each module to execute at independent timing without mutual interference, reducing overall processing load while maintaining coordination through standardized interface signals.
Solution Approach 2:
The patent introduces intermediary elements including a boost voltage command generation unit that translates motor requirements into boost control commands, and a coordinate transformation unit that converts between different reference frames. These intermediaries act as buffers between the independent control processes, enabling coordination without requiring simultaneous execution.
2Measurement precision
If current feedback control process is used for precise current control, then current control precision is improved, but processing load increases and control speed decreases
Solution Approach 1:
The system performs preliminary actions by pre-calculating voltage commands based on current commands and motor parameters before the actual current control execution. The boost control generates voltage commands in advance, and the inverter applies these pre-calculated commands to the motor, reducing the real-time computational burden during current feedback control while maintaining precision.
Solution Approach 2:
The patent replaces complex mechanical/computational feedback control mechanisms with a simplified control architecture that uses pre-calculated voltage commands and direct current command application. Instead of iterative feedback adjustment, the system uses a direct control path where voltage commands are generated based on current commands and applied immediately, reducing processing load while maintaining control precision.
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 reduces processing load and enables high-speed control processes without mutual interference, allowing for appropriate boost voltage setting even with varying counter electromotive voltage and temperature conditions, and expands the motor's operational range by supplying weak field current during boost control.
Implementation Method 1
a boost circuit which is provided on an input side of the inverter circuit and has at least a reactor and a switching element, and controls ON and OFF states of the switching element of the boost circuit on the basis of a boost voltage command
Implementation Method 2
a boost voltage command setting unit which sets the boost voltage command on the basis of counter electromotive voltage of the brushless DC motor and a torque command for the brushless DC motor
Data Source
AI summary
A control device of a boost converter which includes: an inverter circuit which controls switching to apply current to a stator winding of respective phases of a multi-phase brushless DC motor; and a boost circuit which is provided on an input side of the inverter circuit and has at least a reactor and a switching element, and controls ON and OFF states of the switching element of the boost circuit on the basis of a boost voltage command which is a command for boost voltage output from the boost circuit, the control device is provided with a boost voltage command setting unit which sets the boost voltage command on the basis of counter electromotive voltage of the brushless DC motor and a torque command for the brushless DC motor.