Rotary Machine Controller Voltage Protection Strategy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In rotary electrical machines with a permanent magnet-type rotor, disconnecting the DC power source can lead to excessive voltage generation across the power conversion circuit, causing damage to connected circuit components due to the inability to maintain control and manage the short-circuiting of armature coils effectively.
Innovation Solution
Implementing a control device with a three-phase full bridge power conversion circuit and a controller that performs three-phase short circuit control and two-phase short circuit control to manage armature coil short-circuiting, ensuring the voltage across the DC terminals remains within a safe range, thereby preventing component damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DC power source is disconnected from the power conversion circuit, then the system can be protected from overcharging, but excessive voltage is generated across the DC terminals causing damage to circuit components
Solution Approach 1:
The controller detects battery disconnection status in advance and proactively switches the power conversion circuit to a protective state before excessive voltage can damage components. The controller monitors the connection status and prepares the circuit for voltage management when disconnection is detected.
Solution Approach 2:
The controller acts as an intermediary between the battery and the power conversion circuit, managing the transition and voltage levels when the battery is disconnected. It controls the switching elements to regulate voltage and prevent direct exposure of the circuit to damaging voltage levels.
2Productivity
If the controller loses ability to control power generation output, then battery charging can continue autonomously, but voltage across DC terminals becomes excessive and destroys circuit components
Solution Approach 1:
The power conversion circuit is designed to autonomously switch to a protective state when the battery is disconnected, without requiring continuous controller intervention. The circuit self-regulates by switching elements to maintain voltage within safe ranges even when the controller can no longer actively manage power generation.
Solution Approach 2:
The circuit includes protective mechanisms that cushion against voltage spikes before they can reach damaging levels. The switching elements and circuit topology are configured to absorb and dissipate excess voltage energy, protecting components from voltage surges that would occur without controller management.
3Reliability
If three-phase short circuit control is implemented to prevent excessive voltage, then component protection is improved, but control complexity increases
Solution Approach 1:
The control mechanism is segmented into discrete switching elements that can be independently controlled. Each phase of the power conversion circuit has dedicated switching elements that can be activated or deactivated based on battery connection status, allowing granular control without requiring complex overall system redesign.
Solution Approach 2:
The control system changes operational parameters (switching states of elements) based on detected battery connection status. When disconnection is detected, the controller changes the switching parameters to establish a protective configuration, transitioning the circuit from normal operation to voltage-protection mode through parameter adjustment rather than structural modification.
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
The control device effectively prevents excessive voltage generation and maintains operational control of the rotary electrical machine, ensuring the reliability of the system by managing armature coil short-circuiting and maintaining a stable voltage range during power source disconnection.
Implementation Method 1
a rotary electrical machine provided with a rotor, the magnetic field of which is formed by a permanent magnet
Implementation Method 2
when the rotary electrical machine is operated as an AC power generator, the power conversion circuit is made to function as a rectifier and a charging current is supplied from the armature coil to the DC power source
Implementation Method 3
a power conversion circuit provided with three legs having upper and lower arms provided with a switch element and a feedback diode connected in antiparallel to the switch element
Implementation Method 4
A smoothing capacitor is connected between the pair of DC terminals of the power conversion circuit
Data Source
AI summary
A control device for controlling a rotary electrical machine functioning as a motor and as a power generator, the device being provided with a power conversion circuit serving to function as an inverter for supplying a drive current from a battery to the rotary electrical machine and as a rectifier for rectifying the power generation output of the rotary electrical machine and supplying the output to the battery; and being provided with a controller for controlling the conversion circuit so that three-phase armature coils of the rotary electrical machine are short-circuited when the battery is disconnected from the conversion circuit and the DC output voltage of the conversion circuit becomes excessive, after which, when the DC output voltage of the conversion circuit decreases to a set low voltage, the short circuit of one phase of the armature coil is released and only two phases are short-circuited.