# A Deadbeat Current and Flux Vector Control for IPMSM Drive with High Dynamic Performance
## 5 Evaluation Results
### High Dynamic Performance Verification  
To examine the dynamic performance of the proposed DB-CFVC, the experiments are performed, and the results are compared with two benchmark methods, i.e., the DB-PCC [11] and DB-DFVC [18]. All candidates are configured with the same sampling and control periods and speed loop bandwidth for a fair comparison. In these experiments, rotor speed, output torque, stator flux linkage, and current are considered in the evaluation of dynamic performance and output quality such as speed response, operating current (as shown in Figure 6a), torque ripple, and flux linkage ripple (as shown in Figure 7). Furthermore, the voltage commands of the three methods are analyzed and compared (as shown in Figure 6b) to track the voltage saturation problem. Two test scenarios include: (a) speeding up from standstill to the base speed (2300 rpm) under heavy load (2.5 Nm), and (b) speeding down gradually with a few steps to a low speed (100 rpm) to assess the driving performance of the three candidates (i.e., the proposed DB-CFVC, the conventional DB-PCC, and DB-DFVC) in the transient and steady states. Figure 6: Experiment results of dynamic performance comparison between DB-PCC, DB-DFVC, and proposed DB-CFVC: (**a**) comparison of response time as sped up to 2300 rpm at load torque 2.5 Nm; (**b**) zoom-in at the points (**1**-**3**) in (**a**) to analyze voltage command waveforms. Figure 7: Comparison of speed, torque, flux linkage, and current between conventional DB-PCC, DB-CFVC, and proposed DB-CFVC at steady state under load torque of 2.5 Nm at various speed, references of (**a**) 2300 rpm, (**b**) 1300 rpm, and (**c**) 100 rpm. The results displayed in Figure 5(a) compare the dynamic performance of the proposed DB-CFVC with the other methods in terms of speed response and output currents under the same load conditions and speed commands. As can be seen, the conventional DB-PCC shows the lowest dynamic response with large current spikes in the transient states when the speed descends. With the conventional DB-DFVC, the output speed cannot attain the base speed under the heavy load condition. In the two conventional methods, their voltage commands both exceed the allowable limit (and then they saturate at 58 V), as seen in Figure 5(b)-1,b-2, or the voltage commands fluctuate while the current exceeds the limit during speeding down, as seen in Figure 5(b)-1. The possible reasons are that, in the transient state when the motor speed is close to the base speed, the generated BEMF would be large. When this is combined with a large difference (or error) between the reference and feedback values of the variables calculated in the synchronous frame, e.g., the torque and flux linkage in the DB-DFVC or the \(d\)-\(q\)-axis current in the DB-PCC, the voltage command obtained is likely to exceed the allowable range after being computed with a high bandwidth deadbeat controller. In practice, in the conventional DB-PCC case (as shown in Figure 5(b)-1), the actual and reference \(d\)-\(q\)-axis currents' direction may alter rapidly during fast speeding down and affect each other. Consequently, the voltage commands may be out of range. This would further result in rapid voltage fluctuations and overcurrent due to the reaction from the \(d\)-\(q\)-axis current regulated by the deadbeat control to follow the step-falling speed command. Regarding the conventional DB-DFVC case (as displayed in Figure 5(b)-2), the \(t\)-axis voltage saturates at the voltage limit while the \(f\)-axis voltage is nearly maintained. Thus, the magnitude of the output voltage vector is insufficient as truncated by modulation of the SVPWM, resulting in output torque shortage and fluctuation (causing output speed (2200 rpm) to be lower than the reference value (2300 rpm)). For the proposed DB-CFVC result (as shown in Figure 5(b)-3), the voltage limit issues have been included in the computations of stator flux linkage reference using the \"reinforced\" phase angle concept (as depicted in Section 3.5).