Synchronous Motor Control Apparatus Dynamic Braking Demagnetization
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Solution Overview
Problem
Existing control apparatuses for synchronous motors during dynamic braking operations often lead to demagnetization due to sudden changes in current, limiting torque generation and failing to completely suppress demagnetization.
Innovation Solution
A control apparatus that includes a current command generation unit, current detection unit, and short-circuit control unit, which delays the initiation of dynamic braking by controlling the q-phase current to decrease after receiving a dynamic braking signal, thereby reducing the d-phase current and preventing demagnetization without excessive torque limitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If dynamic braking is initiated immediately after receiving the braking signal, then the emergency stop response is fast, but the d-phase current increases momentarily causing demagnetization
Solution Approach 1:
The control apparatus performs preliminary action by detecting the q-phase current before initiating dynamic braking. When the q-phase current exceeds a predetermined threshold, the control apparatus delays the dynamic braking initiation. This preliminary detection and conditional delay prevents the momentary increase in d-phase current that would cause demagnetization, while still maintaining fast emergency stop response when the q-phase current is within safe limits.
2Object-affected harmful factors
If the q-phase current is limited beforehand to suppress demagnetization, then demagnetization is prevented, but the torque is limited unnecessarily
Solution Approach 1:
The control apparatus applies dynamics by adaptively adjusting the dynamic braking initiation timing based on real-time q-phase current conditions. Instead of statically limiting the q-phase current beforehand, the system dynamically determines whether to delay braking initiation based on whether the q-phase current exceeds a threshold. This dynamic approach prevents demagnetization only when necessary, maintaining full torque generation capability during normal operating conditions.
3Productivity
If the short-circuiting device is controlled to short-circuit immediately, then the dynamic braking effect is immediate, but the current oscillation amplitude becomes large causing demagnetization
Solution Approach 1:
The control apparatus employs feedback by continuously monitoring the q-phase current and using this information to control the short-circuiting device. The feedback mechanism compares the detected q-phase current against a predetermined threshold and adjusts the timing of short-circuit initiation accordingly. This feedback control prevents large current oscillations and demagnetization while maintaining effective dynamic braking, as the short-circuiting is initiated at the optimal moment based on real-time current conditions.
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 solution effectively suppresses demagnetization during dynamic braking operations by managing current changes, ensuring the synchronous motor's stability and maintaining torque generation capabilities.
Implementation Method 1
a current that is caused to flow through the three-phase coil due to an induced voltage of the motor 100 is used as a control current to brake the motor 100
Implementation Method 2
the q-phase current Iq (torque generation current), which is in opposite direction so as to cancel the counter electromotive voltage Kvω, flows in the motor so that braking occurs
Data Source
AI summary
A control apparatus of a synchronous motor according to the present invention includes: a current command generation unit for generating a d-phase current command and a q-phase current command; a current detection unit for detecting a d-phase current and a q-phase current; a short-circuiting device for short-circuiting the synchronous motor to apply dynamic braking to the synchronous motor; and a short-circuit control unit for controlling the short-circuiting device; wherein the current command generation unit controls the q-phase current command so as to decrease the q-phase current after receipt of a dynamic braking signal; and the short-circuit control unit controls the short-circuiting device to short-circuit the synchronous motor after the receipt of the dynamic braking signal and after a lapse of a predetermined time from the control of the q-phase current command by the current command generation unit.