Bidirectional Switching Power Amplifier Predictive Current Control
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Solution Overview
Problem
Traditional PI controllers for bidirectional digital switching power amplifiers in magnetic suspension drive platforms face challenges with long dynamic adjustment times, poor system robustness, and high computational demands, requiring complex parameter adjustments and cumbersome weight coefficient tuning, especially in high-power applications.
Innovation Solution
A multi-step current predictive control method for bidirectional digital switching power amplifiers that involves establishing a prediction model, introducing feedback correction terms, and calculating optimal modulation duty cycles using a value function to improve current prediction accuracy, reducing the need for complex parameter settings and weight coefficient adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional PI control is used for bidirectional digital switching power amplifier, then the control structure is simple, but the dynamic adjustment time is long and system robustness is poor
Solution Approach 1:
The patent applies preliminary action by predicting future current values (i(k+1|k) and i(k+2|k)) before they actually occur. The prediction model calculates anticipated current states at k+1 and k+2 sampling moments based on current system state, allowing the controller to prepare optimal duty cycles in advance rather than reacting to actual current deviations, thereby reducing dynamic adjustment time while maintaining simple control structure.
2Measurement precision
If traditional model predictive control is used, then future system state can be predicted, but large amount of on-line computation is required and it is difficult to apply in high switching frequency
Solution Approach 1:
The patent segments the prediction horizon into discrete sampling moments (k, k+1, k+2) with simplified prediction equations for each step. Instead of solving complex continuous-time optimization problems, the system uses segmented discrete-time prediction models that compute future currents at specific sampling intervals, dramatically reducing on-line computational burden while maintaining adequate prediction accuracy for high switching frequency applications.
Solution Approach 2:
The patent changes the computational parameters by using simplified prediction equations with fixed coefficients (TS/L, R/L) rather than solving variable-parameter optimization problems. The prediction model uses constant system parameters (inductance L, resistance R, sampling period TS) to generate future current predictions, transforming a computationally intensive continuous optimization problem into a series of simple discrete calculations suitable for high-frequency switching.
3Measurement precision
If PI controller parameters are adjusted to adapt current control requirements, then control accuracy can be improved, but the tuning process is difficult and parameter adaptation range is small
Solution Approach 1:
The patent applies self-service by eliminating the need for manual PI parameter tuning. The prediction-based control method automatically adapts to different operating conditions through its inherent predictive capability, using system parameters (L, R, TS) that are naturally known or easily measurable. The controller self-adjusts its behavior based on predicted future states without requiring external tuning intervention, expanding parameter adaptation range while improving ease of operation.
Data Source
AI summary
The present application relates to a bidirectional digital switching power amplifier based on a magnetic suspension drive platform and its multi-step current predictive control method. The control method includes the following steps: establishing a prediction model of a bidirectional digital switching power amplifier; introducing a feedback correction term for a closed loop prediction; calculating an optimal modulation duty cycle through a value function; generating, according to the obtained modulation duty cycle, four PWM drive signals by a pulse width modulation module to control four switch tubes respectively to achieve current prediction control. The present application effectively improves the system control accuracy with small steady-state error, small on-line computation amount, simple algorithm, easy digital realization, and good practical value and application prospect.