Parallel Connected Multiple Motor Drive System Using Small Auxiliary Inverter for Permanent Magnet Synchronous Motors

Abstract

This paper proposes a parallel operation system of permanent magnet synchronous motors (PMSMs) and verifies the suppression effect of the proposed damping control for the torque vibration caused by resonance between synchronous reactance and inertia moment. The proposed system is composed by two types of power converters, a main inverter with a V/f control and an auxiliary inverter with the field-oriented control and the damping control. In general, PMSM cannot be driven by the V/f control such as an induction motor because the speed vibration is caused by the resonance between the synchronous reactance and the inertia moment. In the proposed system, the multiple PMSMs are driven in parallel by the main inverter with the V/f control. When the motor speed vibration occurs, the damping control for the auxiliary inverter suppresses this vibration in PMSM. From the frequency characteristics, it is clear that the power capacity of the auxiliary inverter is 10% lower than that of the main inverter when the frequency components included in the speed command are lower than 12 rad/s. As a result, the experimental results demonstrated that the proposed system can reduce the speed vibration from 400 r/min to nearly 0 r/min with the damping control in our prototype of 1500-W PMSM drive system. The experimental results well agree with the theoretical analysis results.

Reduced-Order Feedback Linearization for Independent Torque Control of a Dual Parallel-PMSM System

“…The results of the second inequality in (16) are shown in (17), k must be regulated respect to the constraints (19) and (17) in order to keep the stability of the subsystem (7).…”

“…Based on (11), (19) and (17). After this step, the coupling term w is asymptotically stable under all conditions, therefore, the closed-loop system (13) turns out to bė…”

“…The open-loop machine has a risk of unstable if the machine is under damped [16]. A machine equipped with damping winding has to be used to guarantee the stability [17].…”

A MTPA Control Strategy for Mono-Inverter Multi-PMSM System

“…1) Calculate the evaluation value of each open-loop machine using (22). 2) Choose the machine with the highest value as the master (M 1 ).…”

“…But the demodulation network, which requires high power inductance and capacitor, also increases the total weight of the system and makes a drawback in the initial purpose of a parallel PMSM system. Nagano et al [22] have used the open-loop V/f control method. Each machine is equipped with damping winding to solve the in-stable problem of the V/f method.…”