Motor Control Power Failure Detection via Regenerative State Analysis
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Solution Overview
Problem
Existing motor control apparatuses with PWM rectifiers struggle to detect power failures during regenerative operations, as the DC output voltage does not decrease, leading to delayed or inaccurate detection of power failures at the AC power supply side.
Innovation Solution
A motor control apparatus with a PWM rectifier, an inverter, AC voltage and current detection units, phase calculation, current loop control, and power failure determination units that differentiate between powering and regenerative operations, using current and voltage loop saturation states to accurately determine power failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage amplitude detection method is used to determine power failure, then power failure can be detected in powering operation state, but power failure cannot be detected in regenerative operation state
Solution Approach 1:
The patent applies dynamics by making the detection method adaptive to different operation states. The system dynamically switches between voltage amplitude detection (for powering operation) and current loop saturation detection (for regenerative operation), allowing accurate power failure detection across all operational conditions rather than using a static detection method
Solution Approach 2:
The patent changes the detection parameter based on operation state. In powering operation, voltage amplitude is used as the detection parameter, while in regenerative operation, current loop saturation state becomes the detection parameter. This parameter switching resolves the contradiction by ensuring detectability in both operation modes
2Measurement precision
If simple voltage amplitude detection is used, then device complexity is low, but detection precision during regenerative operation is insufficient
Solution Approach 1:
The patent makes the control system multi-functional by having it perform both normal control functions and power failure detection functions. The existing current loop control hardware is utilized for dual purposes: normal motor control and power failure detection during regenerative operation, eliminating the need for separate detection hardware and reducing overall system complexity
Solution Approach 2:
The system uses its own internal control parameters (current loop saturation state) for self-diagnosis of power failure conditions. Rather than requiring external detection devices, the system monitors its own operational parameters to detect power failures, reducing hardware complexity while maintaining detection 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
Enables accurate detection of power failures during regenerative operations, preventing damage by initiating protective measures and improving safety in motor-driven systems.
Implementation Method 1
a PWM rectifier for performing a bidirectional power conversion between AC power at an power supply side and DC power at a DC link being on a DC side
Implementation Method 2
an inverter for performing a bidirectional power conversion between DC power at the DC link and AC power which is drive power for a motor or regenerative power
Implementation Method 3
an AC voltage detection unit for detecting an AC voltage value at an AC power supply side of the PWM rectifier
Implementation Method 4
a phase calculation unit for calculating a power supply voltage phase from the AC voltage value
Implementation Method 5
an AC current detection unit for detecting an AC current value at an AC power supply side of the PWM rectifier
Implementation Method 6
a current loop control unit for generating an AC voltage command to control a power conversion operation of the PWM rectifier based on an error between an input current command and the AC current value and the power supply voltage phase
Implementation Method 7
an operation determination unit for determining whether the PWM rectifier is in a powering operation state in which AC power is converted to DC power or in a regenerative operation state in which DC power is converted to AC power
Data Source
AI summary
A motor control apparatus includes: a PWM rectifier; an inverter; a detection unit for detecting an AC voltage value of the PWM rectifier; a calculation unit for calculating a power supply voltage phase; a detection unit for detecting an AC current value of the PWM rectifier; a current loop control unit for generating an AC voltage command to control a power conversion operation of the PWM rectifier; a current loop saturation state determination unit for determining to be in a current loop saturation state when a magnitude of the AC voltage command is equal to or larger than a predetermined voltage prescribed value; an operation determination unit for determining whether the PWM rectifier is in a powering operation or in a regenerative operation and a power failure determination unit for determining a presence or absence of a power failure at the AC power supply side from the determination results.