Dual Three-Phase PMSM Control With Alternating Sampling and MPC
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Solution Overview
Problem
Existing dual three-phase permanent magnet synchronous motor drive systems with low switching frequencies suffer from delayed control effects, increased harmonic components, and degraded performance due to intensified coupling and large delay effects, affecting steady-state and dynamic control performance.
Innovation Solution
A control method that alternately performs sampling and control procedures for the dual three-phase windings and corresponding power electronic converters, effectively doubling the equivalent sampling frequency, reducing digital delay, and implementing a two-layer model predictive control scheme to improve control accuracy and reduce computation burden.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low switching frequency operation is used in medium-voltage high-power applications, then the efficiency of power electronic converters is improved and the capacity of the auxiliary heat-dissipation system is reduced, but the delay effect in digital control is intensified and the coupling effect of motor dq-axis component is intensified
Solution Approach 1:
The patent segments the control of dual three-phase windings into two independent sets (first set and second set), with each set having its own sampling and control procedures. This segmentation allows the system to maintain low switching frequency while improving control response by treating each winding set as a separate controllable unit with dedicated sampling moments.
Solution Approach 2:
The patent implements periodic alternating sampling and control procedures for the two sets of windings. The first set is sampled and controlled at one moment, while the second set is sampled and controlled at another moment, creating a periodic action pattern that effectively doubles the equivalent sampling frequency without increasing the actual switching frequency.
2Loss of energy
If low switching frequency operation is used, then power loss is reduced, but the output harmonic components of the power electronic converter increase and control performance is degraded
Solution Approach 1:
By segmenting the control into two independent sets of windings with separate sampling and control procedures, the system can maintain low switching frequency (reducing power loss) while achieving better harmonic performance through the effective doubling of equivalent sampling frequency.
Solution Approach 2:
The patent introduces an intermediary mechanism of alternating sampling and control procedures that acts as a mediator between the low switching frequency operation and the need for high control performance. This intermediary approach allows the system to achieve improved control performance without increasing the actual switching frequency.
3Temperature
If low switching frequency operation is used, then thermal management requirements are reduced, but the bandwidth of the conventional vector control system is reduced and control system stability is affected
Solution Approach 1:
The periodic alternating sampling and control procedures create a time-varying control structure that effectively increases the bandwidth of the control system. By alternating between controlling the first and second sets of windings, the system achieves a higher equivalent sampling frequency and thus higher control bandwidth without increasing the actual switching frequency or thermal management requirements.
4Device complexity
If conventional first-order inertial modeling is used with low switching frequency, then the control structure remains simple, but the modeling error is large and steady-state and dynamic control performance are significantly affected
Solution Approach 1:
The patent segments the motor control into two independent sets of windings with separate modeling and control procedures. This segmentation allows the use of simpler first-order inertial models for each set while achieving better overall control performance through the alternating control strategy that effectively doubles the equivalent sampling frequency.
Data Source
AI summary
In a control method of a dual three-phase permanent magnet synchronous motor by alternately performing sampling and control procedures, sampling instants, vector loading instants, and reference value tracking instants of two sets of windings alternate in two halves of a sampling period, and the equivalent sampling frequency of the motor drive system is doubled and the digital delay and the predictive horizon are halved without changing the sampling frequency of a single set of three-phase windings. In addition, by a two-layer MPC strategy, a deficient-rank problem is settled that the controlled dimensionality of the system is reduced to two dimensions but the motor control objective is still four dimensions caused by the method with controlling a dual three-phase permanent magnet synchronous motor by alternately performing sampling and control procedures.