Motor Drive Converter Voltage Optimization for System Loss Reduction
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Solution Overview
Problem
Existing electric motor drive control systems with variable DC voltage converters do not effectively minimize overall system power loss, leading to inefficiencies in energy conversion from DC to AC voltage for AC electric motors.
Innovation Solution
An electric motor drive control system that includes a DC power source, a converter for boosting and variably controlling the output voltage, and an inverter for power conversion, utilizing loss estimating units and a controller to set the optimal DC voltage that minimizes total power loss across the system by calculating the minimum necessary voltage based on induction voltage and power loss characteristics of the DC power source, converter, inverter, and electric motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the DC voltage output by the converter is varied to adapt to different motor loads, then the adaptability of the system is improved, but the overall system efficiency is not optimized because power loss in each component varies with voltage level
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the DC voltage output level of the converter based on motor load conditions. The control device calculates optimal DC voltage values that minimize total power loss across all system components (converter, inverter, motor) while adapting to varying load requirements. This resolves the contradiction by changing the voltage parameter optimally rather than simply varying it to match load.
Solution Approach 2:
The patent implements feedback control by continuously monitoring motor load conditions and adjusting the DC voltage output accordingly. The control device receives information about motor operation state and feedbacks an optimized voltage command to the converter, ensuring both adaptability to load changes and minimization of overall system power loss.
2Power
If the DC voltage is increased to meet higher motor power demands, then the power delivery capability is improved, but the power loss in the converter and inverter increases
Solution Approach 1:
The patent optimizes the DC voltage parameter by calculating the optimal voltage value that satisfies motor power demands while minimizing power loss. Rather than simply increasing voltage to meet power demands, the control device determines the minimum necessary voltage that achieves the required power output, thereby reducing I²R losses in the converter and inverter.
Solution Approach 2:
The patent applies partial action by providing only the necessary DC voltage level required to meet motor power demands, rather than consistently maintaining high voltage. The control device calculates the optimal voltage as a fraction of maximum capability, applying just enough voltage to satisfy load requirements and minimize losses.
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 allows for the accurate estimation and minimization of total power loss, enhancing the overall efficiency of the system by optimizing the output voltage of the converter, thereby improving the energy conversion process.
Implementation Method 1
a converter (15) configured to allow boosting of an output voltage of the DC power source
Implementation Method 2
an inverter (20, 30) performing electric power conversion between DC power on a DC power line (7) and AC power for driving an electric motor (MG1, MG2)
Data Source
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AI summary
A voltage command value of a converter is set by executing the step (S100 to S140) of determining a candidate voltage of a system voltage VH as a converter output voltage in a voltage range from the minimum necessary voltage (VHmin) corresponding to induction voltage of a motor generator (MG11, MG2) and a maximum output voltage (VHmax) of the converter; the step (S150 to S165) of estimating power loss at the battery, converter, inverter and motor generator, at each candidate voltage, and calculating total sum of estimated power loss of the overall system; and the step (S170 to S190) of setting the voltage command value VH# based on the candidate voltage that minimizes the total sum of estimated power losses among the candidate voltages.