Inverter Drive Voltage Generation Over-Modulation Control
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Solution Overview
Problem
Existing driving circuit technologies for electric vehicle propulsion systems face inefficiencies in generating high-amplitude fundamental voltages, leading to increased energy loss due to unnecessary switching operations when using space vector pulse width modulation (SVPWM) in over-modulation ranges.
Innovation Solution
A driving circuit controller decouples field flux linkage and torque components of the reference voltage signal into orthogonal directions, determining if the reference space vector falls within a holding region, and adjusts it to match a predetermined space vector associated with that region to minimize switching instances and reduce energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If existing methods of introducing harmonics to generate high-amplitude fundamental voltages are used, then the desired high-amplitude fundamental voltage can be achieved, but the number of switching operations increases causing larger than necessary energy loss
Solution Approach 1:
The patent changes the modulation strategy by introducing a holding angle parameter that determines when to hold the space vector at predetermined positions. By adjusting this holding angle parameter, the system optimizes the balance between maintaining high fundamental voltage amplitude and reducing switching operations in over-modulation regions, thereby reducing switching loss while preserving power output.
2Power
If the amplitude of fundamental voltage is increased beyond linear modulation limits, then high-power output is achieved, but additional harmonics are introduced requiring more switching operations
Solution Approach 1:
The patent applies preliminary action by pre-determining holding angles and holding regions before actual voltage generation. The controller pre-calculates the optimal holding angle based on the desired fundamental voltage amplitude, and pre-identifies holding regions in the space vector diagram. This preliminary preparation allows the system to directly implement the optimized switching pattern without real-time complex calculations, reducing switching operations while maintaining high voltage amplitude.
3Power
If over-modulation is applied to achieve high fundamental voltage amplitude, then power output is improved, but switching loss increases due to increased switching instances
Solution Approach 1:
The patent implements dynamics by making the space vector control adaptive to the operating region. The holding angle is dynamically adjusted based on the modulation index and operating conditions. When operating in over-modulation region, the system dynamically switches to holding space vectors at predetermined positions for durations determined by the holding angle, thereby dynamically optimizing the trade-off between voltage amplitude and switching loss.
Data Source
AI summary
Circuits, methods, and systems for driving a load are described. An exemplary driving circuit may include a plurality of switching devices and a controller electrically connected to the switching devices. The controller may be configured to receive a reference voltage signal indicating a target voltage for the driving circuit to generate to drive the load. The reference voltage signal may correspond to a reference space vector in a reference frame. The controller may also be configured to determine that the reference space vector falls within a holding region in which the reference voltage signal is subject to over-modulation. The controller may then generate an adjusted reference voltage signal by adjusting the reference space vector to match a predetermined space vector associated with the holding region. In addition, the controller may be configured to provide the adjusted reference voltage signal to the plurality of switching devices to drive the load.