PMSM Rectifier Control for Stable DC Bus Voltage Without Speed Sensing
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Solution Overview
Problem
Existing control methods for rectifiers connected to permanent magnet synchronous electric generators require knowledge of the electric machine's operating characteristics, such as torque setpoint and rotor speed, which can be impractical or unavailable in certain applications.
Innovation Solution
A control method for rectifiers that determines vector component setpoints independently of the electric machine's operating characteristics, using an external regulation loop to manage DC bus voltage or battery current, with optional defluxing mechanisms to limit current amplitude within predefined thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If control methods use torque setpoint and rotor speed measurements to determine phase current setpoints, then the control precision is improved, but the device complexity and measurement requirements increase
Solution Approach 1:
The patent extracts and eliminates the dependency on torque setpoint and rotor speed measurements from the control system. By formulating the control method to determine phase current setpoints solely from voltage measurements and electrical machine parameters, the solution removes the need for additional sensors and complex measurement systems while maintaining effective control precision
Solution Approach 2:
The patent introduces an intermediary approach by using voltage measurements as the primary input signal and deriving current setpoints through mathematical relationships involving electrical machine parameters. This intermediary method replaces direct torque and speed measurements with a computational approach that achieves control precision without additional measurement complexity
2Power
If the amplitude of phase currents is increased to meet load demands, then the power output is improved, but the thermal losses increase
Solution Approach 1:
The patent implements dynamic current control by continuously adjusting the phase current setpoints based on real-time voltage measurements and load conditions. The control method dynamically optimizes the current amplitude and phase angle to meet power demands while minimizing thermal losses through adaptive regulation rather than fixed high-current operation
Solution Approach 2:
The patent changes the control parameters from fixed torque-based current setpoints to dynamically calculated values based on voltage measurements and electrical machine characteristics. By adjusting current magnitude and phase angle as variable parameters rather than fixed values, the system achieves optimal power output with reduced thermal losses under varying load conditions
Data Source
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AI summary
This method comprises: determining a first setpoint (Iq_ref) for a first vector component (Iq) of the phase currents (Ia, Ib, Ic) along a first axis (q) of a rotating reference frame (R) connected to a rotor (112) of the electric generator (108), and a second setpoint (Id_ref) for a second vector component (Id) of the phase currents (Ia, Ib, Ic) along a second axis (d) of the rotating reference frame (R), this second vector component (Id) of the phase currents (Ia, Ib, Ic) being intended to bring about defluxing of the rotor (112); and controlling the rectifier (118) on the basis of the first and second setpoints (Iq_ref, Id_ref) for the vector components (Iq, Id) of the phase currents (Ia, Ib, Ic). The first setpoint (Iq_ref) for the first vector component (Iq) of the phase currents (Ia, Ib, Ic) is determined on the basis of an external feedback loop designed to feedback-control a voltage on a DC bus or to regulate a current from a battery connected to the DC bus.