Motor Drive Device Bus Voltage Control Without Communication
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Solution Overview
Problem
Existing motor drive systems require communication means between converter and inverter devices to prevent excessive input current, leading to increased system construction costs, longer construction periods, and potential malfunctions due to noise interference and delay in control signals.
Innovation Solution
A motor drive device that includes a converter circuit to convert AC power to DC power and an inverter circuit to drive the motor, with control units to limit input current and output power based on bus voltage detection, eliminating the need for communication means by using existing detection signals for control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If communication means are provided between converter device and inverter device to prevent excessive input current, then control reliability is improved, but device complexity and system construction cost increase
Solution Approach 1:
The inverter device autonomously monitors the bus voltage and detects converter device status without requiring communication from the converter device. The inverter device independently determines whether to limit output power based on voltage thresholds, eliminating the need for communication means in the converter device while maintaining control reliability.
Solution Approach 2:
The inverter device's control unit performs multiple functions: it controls the inverter circuit, monitors bus voltage, detects converter status, and limits output power when necessary. By consolidating these functions in the inverter device, the system eliminates dedicated communication means while achieving the same control objectives.
2Measurement precision
If communication means are provided to transmit detection information, then control precision is improved, but system construction time and cost increase
Solution Approach 1:
The invention extracts the communication function from the converter device and relocates it to the inverter device. The inverter device directly monitors the bus voltage to detect converter status, eliminating the need for separate communication circuits and reducing system construction time while maintaining detection precision.
3Measurement precision
If communication means are provided for fine control, then control accuracy is improved, but noise interference and delay time increase
Solution Approach 1:
The bus voltage serves as an intermediary signal that indirectly conveys converter device status to the inverter device. By monitoring the bus voltage rather than using direct communication, the system avoids noise interference and delay associated with communication circuits while maintaining accurate detection of converter status.
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
Prevents unexpectedly large input currents and powers without communication means, reducing system scale and construction costs, and enabling high-speed control by maintaining input currents and powers within set limits.
Implementation Method 1
a converter circuit to convert the AC power into DC power
Implementation Method 2
an inverter circuit to drive the motor by converting the DC power supplied from the converter circuit into AC power
Data Source
AI summary
A motor drive device receiving AC power supplied from an AC source and driving a motor includes: a converter circuit converting the AC power into DC power; an inverter circuit converting the DC power into AC power to drive the motor; and a current detector detecting input current flowing on the AC side of the converter circuit. The motor drive device also includes a converter device and an inverter device. The converter device includes a control unit performing control such that input current or input power supplied to the converter circuit does not exceed an upper limit, based on a value detected by the current detector. The inverter device includes a control unit detecting voltage of a DC bus connecting the converter circuit and the inverter circuit, and limiting the output power of the inverter circuit when a detection value of the bus voltage decreases to a set lower limit.